Design and Development of a Multifunctional Stepladder: Usability, Sustainability, and Cost-Effectiveness

Abstract

This study presents the design, development, and evaluation of a multifunctional stepladder that integrates four functionalities: a stepladder, Pilates chair, wheelchair, and walking aid. Unlike existing research that focuses on single-function assistive devices, this study uniquely integrates a stepladder, wheelchair, walking aid, and Pilates chair into one multifunctional device, offering a compact, space-saving solution that addresses multiple daily needs in a single design. Building upon previous research, which conceptualized a multifunctional stepladder by synthesizing ideas, features, and functions from patent literature, existing products, and scientific articles, this study focuses on the design and testing phases to refine and validate the concept. Using sustainable materials like mild steel and aluminium, the design was optimized through structural simulations, ensuring durability under loads of up to 100 kg. Usability tests revealed that the invention significantly reduced task completion times, saved five times the space compared to single-function products, and provided enhanced versatility. Cost analysis highlighted its affordability, with a retail price of MYR 1392—approximately 35% lower than the combined cost of its single-function counterparts. Participant feedback noted strengths such as eco-friendliness, practicality, and ergonomic design, alongside areas for improvement, including portability, armrests, and storage. Future work includes enhanced portability for stair navigation, outdoor usability tests, and integration of smart technologies. This multifunctional stepladder significantly contributes to caregivers by reducing the physical burden of managing multiple assistive devices, enhancing efficiency in daily caregiving tasks, and providing a safer, more convenient tool that supports both mobility and exercise for elderly users. This multifunctional stepladder also offers a sustainable, cost-effective, and user-centric solution, addressing usability gaps while supporting global sustainability and accessibility initiatives.

1. Introduction

Stepladders are essential tools used across various settings, including residential, commercial, and industrial applications. Their simplicity and versatility make them indispensable for tasks ranging from home maintenance to professional construction. However, despite their widespread use, conventional stepladders have significant limitations in terms of adaptability, safety, and sustainability. Many designs are task-specific, lacking the flexibility required to meet diverse user needs. Additionally, stepladders often fail to incorporate ergonomic features that prioritize user safety and comfort, leading to inefficiencies and an increased risk of accidents. Moreover, while advanced multifunctional ladders are available in the market, they are often prohibitively expensive, leaving cost-conscious consumers without viable options.

Sustainability in assistive devices is increasingly vital as global efforts focus on minimizing environmental impact and promoting responsible production. Sustainable assistive devices prioritize eco-friendly materials, such as recyclable metals or responsibly sourced wood, and design for longevity to reduce waste and resource consumption. Incorporating sustainability ensures that these devices not only assist users but also align with broader environmental goals like reducing carbon footprints and supporting circular economies. Similarly, universal design plays a critical role in multifunctional assistive furniture, aiming to create products that meet users’ needs without the requirement for adaptation. Universal design ensures inclusivity, improves safety, and enhances user experience, particularly in elderly care and rehabilitation settings, where physical limitations vary widely.

Cost-effectiveness in multifunctional furniture is equally significant, as it directly impacts affordability and accessibility. By integrating multiple functions—such as combining a stepladder, wheelchair, walking aid, and Pilates chair into one device—the need to purchase separate equipment is eliminated, reducing costs for individuals, caregivers, and institutions. This approach not only lowers initial expenses but also minimizes maintenance, storage space, and material usage, further contributing to sustainability.

Discussing real-world application scenarios is crucial in understanding the practical value of multifunctional assistive furniture. For instance, in eldercare homes, rehabilitation centres, or small urban apartments, where space and resources are limited, multifunctional devices can improve efficiency, ease daily activities, and promote independent living. Such scenarios validate the product’s usability, showcase its adaptability in diverse environments, and highlight its potential impact on improving the quality of life for users while supporting sustainability and cost-saving objectives.

To date, there has been little research aimed at developing a cost-effective, multifunctional stepladder that integrates enhanced usability and sustainability—a gap this study aims to address. Hence, this research addresses the gap in developing a cost-effective, multifunctional assistive device that combines a stepladder, wheelchair, walking aid, and Pilates chair into one compact design, which is lacking in existing products. This study aims to identify optimal materials, perform structural analysis, test usability, and evaluate cost-effectiveness to create a sustainable, user-friendly device that reduces caregiver workload and supports elderly users in daily activities.

The summative usability test in the study evaluated the multifunctional stepladder’s overall performance, efficiency, and user satisfaction in real-world scenarios. It involved comparing task completion times and space usage and collecting user feedback against conventional single-function devices. The results showed that the multifunctional stepladder significantly reduced task times, saved space, and received positive feedback for practicality and convenience. However, users also noted areas for improvement, such as portability and the need for additional features like armrests, confirming the device’s usability while identifying refinements for future development.

1.1. Challenges with Existing Stepladders

One of the primary challenges with existing stepladders is their lack of versatility. Most designs are limited to a single-purpose use, with fixed dimensions and configurations that restrict their functionality, which often necessitates the purchase of additional equipment. This not only increases costs for users but also results in inefficient utilization of space and resources.

Cost is another barrier to the adoption of advanced stepladder designs. These step ladders are often expensive, making them inaccessible to many users. The high cost arises from the use of specialized materials and complex manufacturing processes, which could be simplified to lower production costs without compromising quality.

Finally, there is a lack of focus on sustainability in the design and production of stepladders. Many models are made using non-recyclable materials or involve processes that contribute to significant carbon emissions. This not only increases the environmental footprint of these products but also contradicts global efforts to promote sustainable development.

Despite these limitations, there appears to be no significant research dedicated to addressing the combined challenges of usability, affordability, and sustainability in stepladder design. This absence of innovation has left a gap in the market, one that this study aims to fill.

This research seeks to overcome the limitations of existing stepladder designs by developing a multifunctional stepladder that is both cost-effective and user-friendly. The primary goal is to create a product that balances functionality, affordability, and sustainability, thereby meeting the needs of a broad user base while supporting global sustainability initiatives.

Affordability is addressed through the use of durable materials such as wood. These materials are not only cost-effective but also environmentally friendly, aligning with the principles of SDG 12: Responsible Consumption and Production. Additionally, the manufacturing process is optimized to minimize waste and energy consumption, further reducing costs and environmental impact.

This study emphasizes sustainability by incorporating recyclable materials and eco-friendly production methods. This approach supports global sustainability goals, particularly SDG 9: Industry, Innovation, and Infrastructure by demonstrating the potential for innovative design solutions that are economically and environmentally viable. Furthermore, the design prioritizes SDG 3: Good Health and Well-being by ensuring that safety and user comfort are central to the product’s development.

This paper details the design and testing phases of the multifunctional stepladder, providing insights into its potential applications and contributions to sustainable development. In previous research done by Gan et al. [1], an invention of a multifunctional stepladder was conceptualized by synthesizing ideas, features, and functions drawn from patent literature, existing products, and scientific articles. Therefore, the aim of the present study is to build upon previous research through the design and testing phases of the multifunctional stepladder. Through innovative engineering and sustainable practices, the proposed multifunctional stepladder offers a cost-effective, user-centric solution that enhances functionality while minimizing environmental impact.

The following research objectives are proposed for this study based on the problem statement and general aim. Each research objective comprises a few research questions (RQs).

• To identify optimal materials and perform a comprehensive mechanical analysis for the design of a multifunctional stepladder.

RQ1. 

What are the maximum load conditions that the multifunctional stepladder could withstand in regard to the material selection?

2.

To test the usability of the multifunctional stepladder.

RQ2. 

How usable is the multifunctional stepladder?

3.

To analyse the cost-effectiveness of the multifunctional stepladder.

RQ3. 

Can the cost of the invention be saved in the design and development process?

RQ4. 

Is the estimated selling price of the invention lower compared to the selling price of competitor products?

1.2. Recent Studies Related to Multifunctionality

In regard to stepladders, Skubic et al. [2] designed a stepladder that includes a first frame, second frame, and platform assembly. However, there appear to be no other functions besides the stepladder function in this design. The invention might also be difficult to carry around due to its weight and size.

While Rui and Gao [3] designed a new multifunctional wheelchair to address the requirements of strength and safety for the elderly, the invention may not be suitable for domestic or outdoor tasks, as the design is complex due to the use of multiple components.

In regard to multifunctional furniture, Wartes [4] invented multifunctional pegged furniture that can function as an alternate chair, step stool, hamper, two-level table, bench, chest, rocking bench, toy box, and cradle. Yen and Yang [5] invented a multifunctional folding table that can be mounted in a tight space in the kitchen, dressing room, laundry room, and garage. Lee [6] invented a multifunctional chair that has a widened usage range and can be transformed to serve as a deck chair or a ladder.

In managing mobility problems for the elderly, Gu et al. [7] designed a multifunctional combined walking aid. However, the invention appears to be expensive, since it contains characteristics of dynamic and static systems.

The multifunctional stepladder shares conceptual similarities with the multifunctional lawnmower designed by Kang et al. [8], which emphasizes combining diverse functions into one device to optimize space, reduce costs, and improve usability. Both studies explore modular design, material selection, and user interaction to achieve multifunctionality, though the stepladder uniquely integrates healthcare and mobility support. Similarly, the framework on torque and sensation in pinch force by Ng et al. [9] underlines the importance of user control and feedback—critical in assistive devices like the stepladder, where safe transitions between modes rely on intuitive handling and minimal effort from elderly users or caregivers. Integrating such ergonomic principles can enhance user experience and safety during transformations.

Additionally, a biomedical study on assistive devices by Lim and Ng [10] underscores material selection, safety, and mechanical performance, which are key factors that align with the stepladder’s structural simulations and material choices.

McJames [11] designed an exercise bench with enhancements allowing obese and elderly people to participate in exercises performed on a conventional exercise bench. Nonetheless, the invention appears to be heavy and bulky, which may cause difficulties in portability.

Pliner et al. [12] studied the factors influencing task performance on a stepladder in older people and found that upper limb control, strength, balance, cognitive processing speed, and psychological domains were significantly associated with ladder task completion time. However, the study alludes to the notion that there may be usability issues in existing stepladder designs since redesigns might be needed to potentially reduce ladder falls and associated injuries.

Wei [13] introduced the application of various energy-absorbing cushioning materials that can act as protective clothing for the elderly. However, the applications seem to be expensive and not easy for the elders to learn the usage, since the applications are quite advanced.

Research conducted by Yeo et al. [14] and Yeo et al. [15] reflects the growing role of sensor technology and smart systems in enhancing functionality and user safety. While their work is on roadway surveillance, the underlying concept of integrating intelligent detection systems can be translated into assistive device design.

Zhao [16] designed cooperative walking equipment that can enable the elderly to exercise healthily and prevent the deterioration of dyskinesia. However, the equipment is not suitable for high-speed or high-precision occasions, as it contains the friction ratchet as its mechanism.

Alvarenga et al. [17] studied the influence of inspiratory muscle training combined with the Pilates method on lung function in elderly women, and the results showed that the Pilate exercise helps in the prevention of disease and maintenance of health. However, the study used only four groups of participants with similar characteristics, which might lead to similar benefits or inaccurate results.

Lee et al. [18] reviewed exercise spaces in parks for older adults, noting that outdoor exercise equipment incorporating fitness, rehabilitation, and play elements is used and positively perceived by senior citizens. However, some outdoor exercise equipment might not be suitable for elders, as it can increase the risk of falls—especially during cold or rainy weather—when used without guidance from younger individuals.

Peijun Li [19] studied the effects of long-term home-based Liuzijue exercise combined with clinical guidance in elderly patients with chronic obstructive pulmonary disease and found that the exercise can improve pulmonary function, exercise capacity, and quality of life in elderly patients with moderate to severe COPD. However, the exercise might not be preferred by individuals from different backgrounds, since Liuzijue is a traditional Chinese fitness exercise.

Table 1. Summary of recent studies related to the present study.

Title	Reference	Key Limitation	Keywords
Stepladder	[2]	There are no other functions besides the stepladder function, and it might be difficult to carry the invention around due to its weight and size.	Not multifunctional, heavy, bulky
Design and Analysis of a Multifunctional Wheelchair	[3]	The invention might not be suitable for household or outdoor tasks as the design is complex due to the use of multiple components.	Complex
Design of a Multifunctional Combined Walking Aid	[7]	The invention appears to be expensive since it has the characteristics of both dynamic and static systems.	Expensive
Exercise Bench with Enhancements that Allow the Obese, Elderly, and Physically Challenged to Participate in Exercise Performed on a Conventional Exercise Bench	[11]	The invention appears to be heavy and bulky to be carried or moved.	Heavy, bulky
Individual Factors That Influence Task Performance on a Stepladder in Older People	[12]	The study alludes to the idea that there may be usability issues in existing stepladder designs since redesigns might be needed to potentially reduce ladder falls and injuries.	Less usable
A Summary of the Research Status and Development Trends of Protective Clothing for the Elderly	[13]	The applications seem to be expensive and may not be easy for elders to use since they are quite advanced.	Not usable, hard to learn and use
Cooperative Walking Equipment for the Elderly	[16]	The equipment is not suitable for high-speed or high-precision occasions as it contains the friction ratchet as its mechanism.	Less usable
The Influence of Inspiratory Muscle Training Combined with the Pilates Method on Lung Function in Elderly Women: A Randomized Controlled Trial	[17]	The study used only four groups of participants with similar characteristics, which might lead to similar benefits or inaccurate results.	Lack of accurate results
Creating Exercise Spaces in Parks for Older Adults with Fitness, Rehabilitation, and Play Elements: A Review and Perspective	[18]	Some outdoor exercise equipment might not be suitable for elders as it can increase the risk of falls, especially during cold or rainy weather, if used without guidance from younger individuals.	Lack of safety
Effects of Long-Term Home-Based Liuzijue Exercise Combined with Clinical Guidance in Elderly Patients with Chronic Obstructive Pulmonary Disease	[19]	The exercise might not be preferred by individuals from different backgrounds, since Liuzijue is a traditional Chinese fitness exercise.	Lack of proven data

presents a summary of recent studies related to the present study, and the key limitations involved.

1.3. Specific Review of Previous Studies

The paper “The Conceptual Development of a Multifunctional Stepladder for Older People and Caregivers”, written by Gan et al. [1], introduces an innovative concept for a multifunctional assistive device aimed at improving mobility for older adults and reducing workload for caregivers. This stepladder integrates the functionalities of a walker, wheelchair, and Pilates chair, offering a versatile and space-saving solution particularly suited for nursing home environments.

The study employed a systematic approach by synthesizing ideas from patents, existing products, and academic literature. Five concepts were developed and screened based on criteria such as usability, simplicity, and multifunctionality. The final design prioritizes practicality, allowing for easy transitions between its four functions while promoting physical activity for the elderly through the Pilates chair feature.

Despite its promise, the design remains at the conceptual stage, with no prototypes developed or user testing conducted. Issues such as safety on uneven surfaces, cost-effectiveness, and the complexity of transitioning between functions require further exploration. Additionally, feedback from caregivers and older adults was not included, which could have enriched the design process.

A follow-up study that will focus on this paper is planned to refine the design, develop a prototype, and conduct real-world testing. This follow-up research will focus on the design and testing phases to refine and validate the concept. Overall, this follow-up study offers a sustainable, cost-effective, and user-centric solution, addressing usability gaps while supporting global sustainability and accessibility initiatives.

2. Research Method

The methodology for developing the multifunctional assistive device follows a clear and structured process, as shown in Figure 1. First, materials were chosen based on their properties and their use in similar products like Pilates chairs, wheelchairs, walking aids, and stepladders. Aluminium and steel were selected because they are strong, lightweight, and commonly used for such devices. Calculations such as beam deflection and Young’s modulus were used to ensure that the device could support a weight of 100 kg, a load chosen to cover extreme use cases. The Ashby chart was employed to compare material properties, confirming aluminium alloys and steel as the best options.

Structural and mode simulations were carried out to test the design’s safety and functionality. Structural simulations analysed the stress, strain, displacement, and safety factors for the device’s components under load. These tests ensured that the parts could withstand pressure during use. The design was also tested in its four functional modes: Pilates chair, stepladder, wheelchair, and walking aid. For each mode, stress and deformation were analysed under specific forces using simulation software (Autodesk Inventor 2019). This step confirmed that the design was safe and practical in all its intended functions.

To improve efficiency, the design was optimized. Components identified as overengineered, such as oversized frames, were adjusted by reducing their dimensions. Material choices were revisited to strike a balance between cost, weight, and safety. These changes resulted in a final design that was lighter and more affordable while maintaining durability and performance. The optimization process also ensured that the device met safety standards without unnecessary materials or expenses.

Usability testing played a key role in evaluating the device’s practicality. Three tests were conducted. The first test compared the time taken to complete tasks with single-function devices versus the multifunctional device in three scenarios. Statistical analysis determined whether the invention saved time. The second test measured the space occupied by single-function devices compared to the multifunctional device, highlighting its space-saving advantage. The third test gathered feedback from users to understand the device’s strengths and weaknesses, ensuring that it meets user needs effectively.

Finally, the results of these tests were analysed and used to refine the design further. Statistical tools, such as Minitab 19, were used to compare time efficiency, while participant feedback was reviewed alongside the test data. The finalized design incorporated optimized features like improved springs and caster wheels to enhance performance and usability. Overall, this methodology integrates material selection, engineering simulations, optimization, and user feedback to create a reliable, efficient, and user-friendly multifunctional assistive device.

2.1. Material Selection from Existing Products

There are different materials that a Pilates chair can be made of [20]. The seat of the Pilates chair is made out of leather material, while the frame and the pedal are made out of steel and wood, respectively. The frame of a walking aid is made up of aluminium, while the wheel is made up of rubber or plastic polyurethane [21,22]. The frame of the wheelchair is made up of aluminium, while the wheel and the seat are made up of rubber and padded plastic, respectively [23]. The frame of the stepladder is made up of aluminium as well [24].

Table 2. Materials used in existing products.

Product	Material	Citation
Pilates chair	Seat: covered with leather or vinyl padding Pedal: covered with leather or vinyl padding Frame: steel	[20]
Walking aid	Frame: aluminium Wheel: rubber or plastic (polyurethane)	[21,22]
Wheelchair	Frame: aluminium Wheel: rubber or plastic (polyurethane) Seat: padded plastic	[23]
Stepladder	Frame: aluminium	[24]

summarizes the materials used in existing products.

2.2. Material Selection Process

In the analysis, it is assumed that the device will support the weight of a 100 kg person, which is a load of 981 N. The weight is set to 100 kg as an extreme case, since the average body mass is 62 kg, and the highest average body mass in North America is 80.7 kg [25]. The length of the beam is set as 900 mm, which is assumed to be the longest component within the invention, thereby making it more susceptible to serious deformation. The moment of inertia formula is based on the hollow rectangular equation. The following equation is used for the material selection process. According to Bongiorno [26], the deflection of the beam should not exceed the length of the beam divided by 180.

$$\mathsf{\delta }={\displaystyle \frac{\mathrm{F}{\mathrm{L}}^3}{48\mathrm{E}\mathrm{I}}}$$

(1)

where

• δ = maximum deflection of the beam = length of beam/180 = 4.277 mm $\approx$ 5 mm
• F = weight of the person = 100 kg = 981 N
• L = length of the beam = 770 mm
• I = moment of inertia = ${\displaystyle \frac{d{o}^4}{12}}-{\displaystyle \frac{d{i}^4}{12}}$ = ${\displaystyle \frac{{(25\times {10}^{-3})}^4}{12}}-{\displaystyle \frac{{(22\times {10}^{-3})}^4}{12}}$ = $1.3031\times {10}^{-8} \mathrm{k}\mathrm{g}{\mathrm{m}}^2$
• E = Young’s modulus

Using the parameters set, Young’s modulus is calculated to be 34.7 GPa. The following equation is used to calculate the diameter of the beam:

$$d=\sqrt{{\displaystyle \frac{m}{L\rho }}}$$

(2)

where

• m = mass of the beam
• $\rho$ = density of the beam
• d = diameter of the beam
• L = length of the beam

By substituting the diameter of the beam into Equation (1), Equation (3) is obtained. The performance index is then obtained by factorization.

$$m={\left({\displaystyle \frac{F{L}^5}{48}}\right)}^{{\displaystyle \frac{1}{2}}}\left({\displaystyle \frac{\rho }{\sqrt{E}}}\right)$$

(3)

$$P={\displaystyle \frac{E^{\frac{1}{2}}}{\rho }}$$

(4)

where

• P = performance index

From the Ashby chart in Figure 2, a line is plotted based on the performance index equation. Another line is also plotted based on the computed Young’s modulus (34.7 GPa). There are many remaining materials to decide on, such as aluminium alloys, magnesium alloys, aluminium, glass, and steel, which are located above the horizontal line. However, aluminium and steel are chosen since these materials are consistently found in the existing products, including wheelchairs, walking aids, Pilates chairs, and stepladders.

The material selection was justified based on the mechanical properties required to ensure the multifunctional stepladder’s safety, strength, and durability. Aluminium and mild steel were chosen because they offer a good balance of strength-to-weight ratio, ensuring that the device is strong enough to support a 100 kg user while remaining lightweight for easier handling. Aluminium was selected for parts requiring lighter weight and corrosion resistance, especially since it is commonly used in similar products like wheelchairs and walking aids. Mild steel was used in areas needing higher strength and rigidity, particularly where heavy loads and structural support are critical.

2.3. Structural Simulation

The structural simulation focuses on the boards of the parts meant for sitting and stepping. The force of 500 N is assigned to the wood, as shown in Figure 3, and the parameters are recorded in

Table 3. Structural simulation of different boards.

Name	Base Board		Bottom Board		Leg Board
	Min	Max	Min	Max	Min	Max
Von Mises stress/MPa	0.03	2.22	0.0279	0.9558	0.066	2.266
1st principal stress/MPa	−0.024	2.01	−0.0255	0.744	−0.031	1.978
3rd principal stress/MPa	−2.214	0.055	−0.9467	0.0051	−2.254	0.066
Displacement/mm	0	0.3661	0	0.02447	0	0.1399
Factor of safety	0	15	0	15	0	15

. The structural simulation for the boards seems to be safe, as the factors of safety are high.

2.4. Modes’ Simulation

There are 4 modes in the proposed invention. Mode 1 is known as the Pilates chair design, Mode 2 is the stepladder design, Mode 3 is the wheelchair design, and Mode 4 is the walking aid design. The analysis of scenario A covers modes 1 and 3. The analysis of scenario B covers modes 3 and 4. The analysis of scenario C covers modes 1 and 2.

Table 4. Simulation of design with stainless steel.

Scenario	Von Mises Stress	Displacement	Safety Factor
A
B
C

shows a simulation of the design using stainless steel. The force applied is 981 N for each situation. The simulation is carried out using Autodesk Inventor 2019.

Table 4 shows the simulation of the design using stainless steel. The force applied is 981 N for each situation. For the stress analysis, the constraints are set at the areas where the frame is welded together.

In scenario A, the force is applied at the centre of the seat. The maximum stress is observed to be 10.84 MPa. The minimum and maximum values for the first principal stresses are observed to be −2.8 MPa and 5.522 MPa, respectively. The minimum and maximum values for the third principal stresses are −13.81 MPa and 1 MPa, respectively. The displacement of the seat is 0.01137 mm, and the equivalent strain is observed to be 0.00005253, both of which are negligible. The factor of safety is 15. The constraints will be the welded area surrounding the sitting platform.

In scenario B, the force is applied at the centre of both handles. The maximum stress is observed to be 20.41 MPa. The minimum and maximum values for the first principal stresses are observed to be −1.52 MPa and 17.19 MPa, respectively. The minimum and maximum values for the third principal stresses are −19.61 MPa and 1.64 MPa, respectively. The displacement of the seat is 0.3483 mm, and the equivalent strain is observed to be 0.00009181, both of which are negligible. For the factor of safety, the minimum and maximum values are 12.25 and 15, respectively. The constraints will be the welded area of the handle surrounding the frame.

In scenario C, the force is applied at the centre of the stepping platform. The maximum stress is observed to be 33.03 MPa. The minimum and maximum values for the first principal stresses are observed to be −4.25 MPa and 26.16 MPa, respectively. The constraint setting will be the area welded surrounding the stepping platform.

The minimum and maximum values for the third principal stresses are −32.97 MPa and 3.68 MPa, respectively. The displacement of the seat is 0.05864 mm, and the equivalent strain is observed to be 0.0001519, which are negligible values. For the factor of safety, the minimum and maximum values are 7.57 and 15, respectively.

Table 5. Simulation of design with aluminium 6061 welded.

Scenario	Von Mises Stress	Displacement	Safety Factor
A
B
C

shows the simulation of the design using aluminium 6061 welded. The force applied is 981 N in each situation.

In scenario A, the force is applied at the centre of the seat. The maximum stress is observed to be 12.13 MPa. The minimum and maximum values for the first principal stresses are observed to be −2.874 MPa and 5.618 MPa, respectively. The minimum and maximum values for the third principal stresses are −15.22 MPa and 1.18 MPa, respectively. The displacement of the seat is 0.0319 mm, and the equivalent strain is observed to be 0.0001645, which are negligible values. For the factor of safety, the minimum and maximum values are 5.22 and 15, respectively.

In scenario B, the force is applied at the centre of both handles. The maximum stress is observed to be at 20.29 MPa. The minimum and maximum values for the first principal stresses are observed to be −1.54 MPa and 17.1 MPa, respectively. The minimum and maximum values for the third principal stresses are −19.68 MPa and 1.27 MPa, respectively. The displacement of the seat is 0.09724 mm, and the equivalent strain is observed to be 0.0002614, which are negligible values. For the factor of safety, the minimum and maximum values are 2.71 and 15, respectively.

In scenario C, the force is applied at the centre of the stepping platform. The maximum stress is observed to be at 33.08 MPa. The minimum and maximum values for the first principal stresses are observed to be −4.54 MPa and 26.45 MPa, respectively. The minimum and maximum values for the third principal stresses are −33.25 MPa and 4.39 MPa, respectively. The displacement of the seat is 0.164 mm, and the equivalent strain is observed to be 0.0004331, which are negligible values. For the factor of safety, the minimum and maximum values are 1.66 and 15, respectively.

Table 6. Simulation of design in different situations before optimization.

Situation	Name	Material with
		Aluminium 6061 Welded		Stainless Steel
		Min	Max	Min	Max
Sitting scenario (Scenario A)	Von Mises stress	0 MPa	12.13 MPa	0 MPa	10.84 MPa
	1st principal stress	−2.874 MPa	5.618 MPa	−2.8 MPa	5.522 MPa
	3rd principal stress	−15.22 MPa	1.18 MPa	−13.81 MPa	1 MPa
	Displacement	0 mm	0.0319 mm	0 mm	0.01137 mm
	Factor of safety	5.22	15	15	15
	Equivalent strain	0	0.0001645	0	0.00005253
Holding handle scenario (Scenario B)	Von Mises stress	0 MPa	20.29 MPa	0 MPa	20.41 MPa
	1st principal stress	−1.54 MPa	17.1 MPa	−1.52 MPa	17.19 MPa
	3rd principal stress	−19.68 MPa	1.27 MPa	−19.61 MPa	1.24 MPa
	Displacement	0 mm	0.09724 mm	0 mm	0.03483 mm
	Factor of safety	2.71	15	12.25	15
	Equivalent strain	0	0.0002614	0	0.00009181
Stepping scenario (Scenario C)	Von Mises stress	0 MPa	33.08 MPa	0 MPa	33.03 MPa
	1st principal stress	−4.54 MPa	26.45 MPa	−4.25 MPa	26.16 MPa
	3rd principal stress	−33.25 MPa	4.39 MPa	−32.97 MPa	3.68 MPa
	Displacement	0 mm	0.164 mm	0 mm	0.05864 mm
	Factor of safety	1.66	15	7.57	15
	Equivalent strain	0	0.0004331	0	0.0001519

shows the data of the design simulation using stress analysis before optimisation. The dimensions of the frame used for the square and circular shapes are 25 mm × 25 mm × 5 mm and 25 mm × 5 mm, respectively. The materials used in this simulation are stainless steel and aluminium 6061 welded. After the simulation, it is observed that some of the factors of safety are high, which implies that the design is overengineered. Therefore, an optimization process is necessary by changing the dimension of the square frame to 20 mm × 20 mm × 2 mm and the circular frame to 21.3 mm × 2 mm. Besides that, the materials used for the simulation are also changed to aluminium and mild steel.

Table 7. Simulation of design with mild steel.

Scenario	Von Mises Stress	Displacement	Safety Factor
A
B
C

shows the simulation of the design using mild steel. The force applied is 981 N in each situation.

In scenario A, the force is applied at the centre of the seat. The maximum stress is observed to be at 91.96 MPa. The minimum and maximum values for the first principal stresses are observed to be −8.2 MPa and 37.83 MPa, respectively. The minimum and maximum values for the third principal stresses are −100 MPa and 5.1 MPa, respectively. The displacement of the seat is 0.3426 mm, and the equivalent strain is observed to be 0.000373, which are negligible values. For the factor of safety, the minimum and maximum values are 2.25 and 15, respectively.

In scenario B, the force is applied at the centre of both handles. The maximum stress is observed to be at 31.9 MPa. The minimum and maximum values for the first principal stresses are observed to be −2.41 MPa and 32.66 MPa, respectively. The minimum and maximum values for the third principal stresses are −32.04 MPa and 2.76 MPa, respectively. The displacement of the seat is 0.03854 mm, and the equivalent strain is observed to be 0.0001276, which are negligible values. For the factor of safety, the minimum and maximum values are 6.49 and 15, respectively.

In scenario C, the force is applied at the centre of the stepping platform. The maximum stress is observed to be at 38.72 MPa. The minimum and maximum values for the first principal stresses are observed to be −8.95 MPa and 35.59 MPa, respectively. The minimum and maximum values for the third principal stresses are −41.17 MPa and 5.98 MPa, respectively. The displacement of the seat is 0.07729 mm, and the equivalent strain is observed to be 0.0001555, which are negligible values. For the factor of safety, the minimum and maximum values are 5.35 and 15, respectively.

Table 8. Simulation of design with aluminium.

Situation	Von Mises Stress	Displacement	Safety Factor
A
B
C

shows the simulation of the design by using aluminium. The force applied is 981 N in each situation.

In scenario A, the force is applied at the centre of the seat. The maximum stress is observed to be at 88.99 MPa. The minimum and maximum values for the first principal stresses are observed to be −9.26 MPa and 37.63 MPa, respectively. The minimum and maximum values for the third principal stresses are −99.6 MPa and 7.52 MPa, respectively. The displacement of the seat is 0.1052 mm, and the equivalent strain is observed to be 0.00118, which are negligible values. For the factor of safety, the minimum and maximum values are 3.09 and 15, respectively.

In scenario B, the force is applied at the centre of both handles. The maximum stress is observed to be at 31.61 MPa. The minimum and maximum values for the first principal stresses are observed to be −2.82 MPa and 32.43 MPa, respectively. The minimum and maximum values for the third principal stresses are −32.37 MPa and 3.01 MPa, respectively. The displacement of the seat is 0.1228 mm, and the equivalent strain is observed to be 0.0004145, which are negligible values. For the factor of safety, the minimum and maximum values are 8.7 and 15, respectively.

In scenario C, the force is applied at the centre of the stepping platform. The maximum stress is observed to be at 38.4 MPa. The minimum and maximum values for the first principal stresses are observed to be −12.9 MPa and 35.37 MPa, respectively. The minimum and maximum values for the third principal stresses are −43.5 MPa and 8.48 MPa, respectively. The displacement of the seat is 0.2437 mm, and the equivalent strain is observed to be 0.0005061, which are negligible values. For the factor of safety, the minimum and maximum values are 7.16 and 15, respectively.

Table 9. Simulation of design in different situations after optimization.

Situation	Name	Material with
		Aluminium 6061		Mild Steel
		Min	Max	Min	Max
Sitting scenario (Scenario A)	Von Mises stress	0 MPa	88.99 MPa	0 MPa	91.96 MPa
	1st principal stress	−9.26 MPa	37.63 MPa	−8.2 MPa	37.83 MPa
	3rd principal stress	−99.6 MPa	7.52 MPa	100 MPa	5.1 MPa
	Displacement	0 mm	0.1052 mm	0 mm	0.3426 mm
	Factor of safety	3.09	15	2.25	15
	Equivalent strain	0	0.00118	0	0.000373
Holding handle scenario (Scenario B)	Von Mises stress	0 MPa	31.61 MPa	0 MPa	31.9 MPa
	1st principal stress	−2.82 MPa	32.43 MPa	−2.41 MPa	32.66 MPa
	3rd principal stress	−32.37 MPa	3.01 MPa	−32.04 MPa	2.76 MPa
	Displacement	0 mm	0.1228 mm	0 mm	0.03854 mm
	Factor of safety	8.7	15	6.49	15
	Equivalent strain	0	0.0004145	0	0.0001276
Stepping scenario (Scenario C)	Von Mises stress	0 MPa	38.4 MPa	0 MPa	38.72 MPa
	1st principal stress	−12.9 MPa	35.37 MPa	−8.95 MPa	35.59 MPa
	3rd principal stress	−43.5 MPa	8.48 MPa	−41.17 MPa	5.98 MPa
	Displacement	0 mm	0.2437 mm	0 mm	0.07729 mm
	Factor of safety	7.16	15	5.35	15
	Equivalent strain	0	0.0005061	0	0.0001555

shows the simulation of the design after optimization. The optimization involves a decrease in the diameter of the frame and a change in materials. The optimization managed to reduce the safety factor to an acceptable range that would not cause the design to be overengineered.

Since the cost and weight of the product needs to be considered, mild steel can be used for the stepping scenario (Scenario C). For the standing scenario (Scenario B), aluminium can be used for the frame because mild steel does not have a chromium oxide protective layer, which might cause the iron to rust. For the sitting scenario (Scenario A), mild steel is preferable since aluminium is more elastic and mouldable compared to mild steel.

2.5. Finalised Design

Figure 4 shows the finalized design based on concept 3 after the process of screening, dimensioning, material selection, and simulation and optimization. The overall dimension of the design is 74 cm × 51 cm × 82 cm in length, width, and height, respectively. The materials used for the design are aluminium and mild steel based on the optimization process.

2.6. Spring Analysis

The spring index is set to 6, since it is cheaper and easier to manufacture springs with this index [27]. The outer diameter from the spring selected (Pilates PRO Chair Extra Resistance Springs) is 31.25 mm [28]. The inner diameter of the coil is calculated to be 5.208 mm based on the following equation.

$$d={\displaystyle \frac{D}{C}}$$

(5)

where

• C = spring index = 6
• D = outer diameter of coil = 31.25 mm
• d = inner diameter of coil

By considering the stress correction factor (computed using the spring index) and the load assigned to the springs, the corrected torsional stress can be calculated using the following equation. Since a total of 2 springs are used to support the load, the force of 981 N (a 100 kg person) is halved.

$$\mathsf{\tau }=\mathrm{K}\mathrm{s}{\displaystyle \frac{8P}{\pi d^3}}$$

(6)

where

• Ks = stress correction factor = ${\displaystyle \frac{4C-1}{4C-4}}$ = 1.15
• P = load assigned to the springs = ${\displaystyle \frac{981}{2}}$ = 490.5 N
• $\mathsf{\tau }$= corrected torsional stress

The corrected torsional stress obtained is 44 MPa, and it is used in the following equation. To calculate the factor of safety, the shearing yield strength needs to be known. From the spring specifications, the shearing yield strength obtained is 525 MPa [29].

$$N_s={\displaystyle \frac{S_{sy}}{\mathsf{\tau }}}$$

(7)

where

• $N_s$ = factor of safety
• $S_{sy}$ = shearing yield strength = 525 MPa

Table 10. The properties of different types of springs.

Spring Type	Diameter (mm)	Ns	Cost
1	31.25	9.91	USD 17
2	31.75	12.06	USD 18
3	24.6	6.85	USD 39

shows the different types of springs that need to be screened to identify the most suitable spring to purchase. The factor of safety obtained for spring type 1 (the calculation demonstrated on the preceding page) is 9.91, which is satisfactory. The factors of safety for spring types 2 and 3 are also obtained from the calculations in the preceding pages. After considering the cost of the spring, spring type 1 is chosen as the design spring since it has a satisfactory factor of safety (9.91) and the cheapest price (USD 17).

2.7. Mechanism and Components

Table 11 shows the mechanisms used for each product. For the Pilates chair, two types of wheels are selected: the height-adjustable wheel and the stop fix caster wheel [30,31]. The caster wheel needs to be stable for the user to do light duty work or exercise safely. An angular contact ball bearing is applied to roll the Pilates chair’s stepping platform [32].

For the walking aid, the handle is made adjustable by using the butterfly screw as the locking mechanism [33]. The adjustable handle is designed using the linear slide locking mechanism [34]. For the wheelchair, the wheel caster lock is selected to secure the wheelchair so that it is safe for users [35]. Since the design is multifunctional, flexibility is important as well. Therefore, the caster wheel is taken into consideration for the Pilates chair. The mechanism used to lock the Pilates chair’s stepping platform for the stepladder function includes a toggle latch clamp [36]. The clamp can sustain up to 700 lbs (317 kg), which is considered safe as a locking mechanism for the step of the stepladder.

Table 11. Mechanism used for different products.

Product	Mechanism	Citation
Pilates chair	Adjustable-height caster wheel	[30]
	Stop fix caster wheel	[31]
	Angular contact ball bearing	[32]
Walking aid	Linear slide lock mechanism	[34]
Wheelchair	Wheel caster lock	[35]
Stepladder	Toggle latch clamp	[36]

Table 11. Mechanism used for different products.

Product	Mechanism	Citation
Pilates chair	Adjustable-height caster wheel	[30]
	Stop fix caster wheel	[31]
	Angular contact ball bearing	[32]
Walking aid	Linear slide lock mechanism	[34]
Wheelchair	Wheel caster lock	[35]
Stepladder	Toggle latch clamp	[36]

Table 12. Comparison of caster wheels for the Pilates chair.

Height-Adjustable Caster Wheel		Stop Fix Caster Wheel
Advantages	Disadvantages	Advantages	Disadvantages
Lower cost Provides stand-alone support without any locking mechanism	Might not provide enough stability for the user Difficult to adjust the legs as support	Provides better stability in locking the wheel with no additional movements Easy to lock	Higher cost

shows the advantages and disadvantages of different caster wheels. Safety and stability are the main concerns. Therefore, the stop fix caster wheel is chosen for the Pilates chair, since it provides better stability by locking the wheel, with no additional movements [37]. Besides that, the stop fix caster wheel can be easily locked compared to the height-adjustable caster wheel, which requires a screwdriver in adjusting the legs as support.

2.8. Usability Test Plan

2.8.1. Test 1 Plan: Time Usage

For the time usage experiments, there are a total of three scenarios to be tested, with each one comprising two cases, namely:

• Case A (control group): Test with 4 single-function products, which include a Pilates chair, a wheelchair, a walking aid, and a stepladder.
• Case B (test group): Test with the multifunctional stepladder (the proposed invention in this study).

The time taken to complete the different scenarios of Case A and Case B is recorded accordingly. The experimentation involves one elderly person, who will be tasked with using single-unit assistive devices (a walking aid, a wheelchair, a Pilates chair) and the proposed invention in the corresponding transformed states (multifunctional stepladder transformed to walking aid, wheelchair, and Pilates chair). The experiment also involves several participants who will act as caregivers, assisting the elderly in using the single-unit assistive devices and the proposed invention and in retrieving items, such as medicine, using the common stepladder and multifunctional stepladder.

Figure 5 shows the floor plan of the test scene. Room 1 is the resting room for the elderly participant, while Room 2 is the room where the elderly participant takes part in the activities of the experiment. There will be a shelf in Room 1 to place items such as medicine for the elderly person. There will be a store next to Room 1 to place the Pilates chair and stepladder. The wheelchair and walking aid will be placed outside the rooms because these assistive items are more likely to be used by the elderly participants.

Scenario 1: This scenario tests the combination of the stepladder and wheelchair. The following instructions are provided to the experimenter for facilitating the control group (Case A) and test group (Case B).

Control group:

• Help the elderly person get into the wheelchair from the bed.
• Start recording the time.
• Move the elderly person on the wheelchair from Room 1 to Room 2 according to the floor plan (for daily activities).
• Move the elderly person from Room 2 back to Room 1 (returning from daily activities).
• Carry a stepladder from the store to Room 1.
• Place the stepladder at point X.
• Use the stepladder to take medicine from a high shelf of the rack.
• The experiment and timer are stopped when the user descends the stepladder at point X.

Test group:

• Help the elderly person get into the wheelchair from the bed.
• Start recording the time.
• Move the elderly person from Room 1 to Room 2 according to the floor plan (for daily activities).
• Move the elderly person from Room 2 back to Room 1 (returning from daily activities).
• Convert the invention from its wheelchair mode to its stepladder mode at point X.
• Use the stepladder function of the invention to retrieve medicine from a high shelf of the rack.
• The experiment and timer are stopped when the user descends from the invention at point X.

Scenario 2: This scenario tests the combination of the walking aid and wheelchair.

Control group:

• Move the wheelchair near the elderly person in Room 1.
• Assist the elderly person in being seated in the wheelchair.
• Start recording the time.
• Move the elderly person from Room 1 to point Z (for the next activity, which includes walking).
• Retrieve the walking aid from the store and return to point Z.
• Assist the elderly person in getting off the wheelchair and standing upright.
• Allow the elderly person to walk independently with the walking aid for 5 s before stopping the experiment and the timer.

Test group:

• Move the wheelchair near the elderly person in Room 1.
• Assist the elderly person in being seated in the wheelchair.
• Start recording the time.
• Move the elderly person from Room 1 to point Z (for the next activity, which includes walking).
• Assist the elderly person in getting off the wheelchair and standing upright.
• Convert the invention from its wheelchair mode to its walking aid mode at point Z.
• Allow the elderly person to walk independently with the invention for 5 s before stopping the experiment and the timer.

Scenario 3: This scenario tests the combination of the Pilates chair and wheelchair. It is important to note that in the control group, the proposed invention (multifunctional stepladder) in its Pilates chair transformed state is to be used as a single-function item (due to cost constraints in purchasing an actual Pilates chair).

Control group:

• Move the wheelchair near the elderly person in Room 1.
• Assist the elderly person in being seated in the wheelchair.
• Start recording the time.
• Move the elderly person from Room 1 to point A and ensure that the area is safe for exercise purposes.
• Retrieve the Pilates chair from the store and return to point A.
• Assist the elderly person in getting off the wheelchair and being seated in the Pilates chair.
• Allow the elderly person to exercise with the invention for 5 s before stopping the experiment and the timer.

Test group:

• Move the wheelchair near the elderly person in Room 1.
• Assist the elderly person in being seated in the wheelchair.
• Start recording the time.
• Move the elderly person from Room 1 to point A, and ensure that the area is safe for exercise purposes.
• Convert the invention from its wheelchair mode to its Pilates chair mode at point A.
• Allow the elderly person to exercise with the invention for 5 s before stopping the experiment and the timer.

2.8.2. Test 2 Plan: Space Availability Test

For the space availability test, four single-function items are placed together at the test scene, and the dimensions for each of the items are measured. After that, the space occupied by the single-function items is recorded down to be compared with the space occupied by the multifunctional stepladder design.

2.8.3. Test 3 Plan: Usability Feedback

This test involves usability feedback from the participants of the experiment in Test 1. Feedback, such as the advantages and disadvantages of the invention, is collected by the researchers.

A hypothesis could then be generated as follows: $H_{usability}$: Users will provide positive feedback on the multifunctional stepladder prototype, indicating higher satisfaction in terms of usability, convenience, and space-saving compared to using separate single-function assistive devices.

The participants involved in the usability tests consisted of a mix of young adults and an elderly individual, representing both caregivers and end users of the multifunctional stepladder. The young adult participants, aged between 20 and 50 years, acted as caregivers, simulating real-world caregiving tasks, such as assisting with transfers and device operation. The elderly participants represented the target user group—older adults who may experience mobility challenges and rely on assistive devices for daily activities. This combination of participants allowed the study to assess the device’s usability, ease of handling, and practicality from both the caregiver’s and the elderly user’s perspectives, ensuring a realistic evaluation of its functionality in caregiving scenarios.

All participants gave their written informed consent prior to the experiments. All procedures and protocols were approved by the Research Ethics Committee (REC) from the Technology Transfer Office (TTO) of Multimedia University. The research ethics approval for the project was granted with approval number EA0112022, and the approval letter was endorsed by the TTO Director cum REC Secretariat of the university and finalized on 7 March 2022.

2.9. Analysis Plan

Minitab Version 19 was used for Test 1, which is the time usage test. The analyses included the two-sample t-test and power analysis. The two-sample t-test was chosen as it involves two groups (control group and test group), and a normality test was done to check whether the data were deemed normal with equal variance. Test 2, which is the space availability test, was analysed by comparing the space used by the single-function items with the space used by the multifunctional stepladder (proposed invention). Test 3 data were analysed by reviewing the participants’ responses on the advantages and disadvantages of the invention and triangulating the feedback with the literature and the tests.

In Test 1, the analyses done for the control group are classified as Case A, while analyses done for the test group are classified as Case B. The null and alternative hypotheses are proposed to compare Case A with Case B. After the test, if the p-value is found to be more than 0.05 (p > α), the null hypothesis is accepted, and the alternative hypothesis is rejected. This result means that the time taken to complete Case A is relatively shorter than Case B, suggesting that it is more efficient and time-saving to use the single-function item compared to the proposed invention. On the other hand, if the p-value is found to be less than 0.05 (p < α), the alternative hypothesis is accepted while the null hypothesis is rejected, and the inference will be the other way around.

Test 1—Scenario 1 Hypotheses:

• Null hypothesis, H_01.1—There is no significant difference in the time taken to complete the tasks between Case A1 and Case B1.
• Alternative hypothesis, H_a1.1—There is a significant difference in the time taken to complete the tasks between Case A1 and Case B1.

3. Results and Discussion

3.1. Final Prototype

The final prototype is designed with a total of four functions, namely the stepladder, wheelchair, Pilates chair, and walking aid functions. Figure 6 shows the invention in its basic form, which is the stepladder (Mode 1). The mechanisms used for each function can be seen in Figure 7.

3.2. Mode Transformation

There are a total of five modes that can be used by the proposed invention. The modes are defined as follows:

Mode 1: Invention in stepladder-transformed state

Mode 2: Pilates chair-transformed state

Mode 3: Wheelchair-transformed state

Mode 4: Walking aid-transformed state

Mode 5: Pilates and wheelchair-transformed state

3.2.1. Mode 1 to Mode 2

Figure 8 shows the proposed invention being transformed from Mode 1 to Mode 3 (basic stepladder form to wheelchair form). The mechanism facilitating this transformation is the support stands, which can be folded up so that the step is flexible (for the Pilates chair function) and folded down so that the step is rigid (for the stepladder function).

3.2.2. Mode 1 to Mode 3

Figure 9 shows the proposed invention’s transformation from Mode 1 to Mode 3. To transform into a wheelchair, the support stands need to be folded upwards, and the wheels need to be unlocked. The handles can also be adjusted wherever necessary.

3.2.3. Mode 1 to Mode 4

Figure 10 shows the invention’s transformation from Mode 1 to Mode 4. To facilitate the transformation to a walking aid (Mode 4), the handles need to be adjusted to accommodate the user’s dimensions, and the wheels need to be unlocked. The user can then walk with the assistance of the walking aid function, which is akin to the function of a wheeled walking aid.

3.2.4. Mode 1 to Mode 5

Figure 11 shows the invention’s transformation from Mode 1 to Mode 5. To facilitate the transformation to a wheelchair cum Pilates chair (Mode 5), the support stands need to be folded upwards, and the wheels need to be unlocked. The seated user will then be able to be moved around in the wheelchair while performing Pilates exercises.

3.3. Results for Test 1: Time Usage

A total of 6 participants (n = 6) were involved in the tests. Each user was required to repeat the test five times to increase the accuracy of the results. Test 1 compared the time taken by each user to complete the transformations in the three scenarios (stepladder to wheelchair, walking aid to wheelchair, and Pilates chair to wheelchair) by comparing the invention with single-function objects.

The Ryan–Joiner test of normality was used to inspect the normality of the data. The test of normality confirmed that the distribution of the data does not significantly differ from being symmetric (p > 0.05). This normality test confirmed that the data were deemed normal, with equal variance. Hence, the dataset is appropriate for further parametric tests.

3.3.1. Power Analysis and Sample Size Estimation

A power analysis for the two-sample t-test was done for all the cases, with the statistical power set at 80%, to predict the actual sample size needed for the experiments. Before proceeding with the power analysis, the mean, standard deviation, mean difference, and pooled standard deviation are calculated using the following equations:

$$\mathrm{Mean}, M={\displaystyle \frac{\sum _0^n{x}_i}{n}}$$

(8)

$$\mathrm{Standard} \mathrm{deviation}=\mathsf{\sigma }=\sqrt{{\displaystyle \frac{\sum _0^n{|x_i-M|}^2}{n}}}$$

(9)

Mean difference = M2 − M1

(10)

$$\mathrm{Pooled} \mathrm{standard} \mathrm{deviation}, \mathrm{S}=\sqrt{{\displaystyle \frac{{{\mathsf{\sigma }}_1}^2-{{\mathsf{\sigma }}_2}^2}{2}}}$$

(11)

Notes:

• x_i—total time taken to complete the test for Case A or B in each scenario
• n—number of samples
• M1—mean value of time taken for Case A in each scenario
• M2—mean value of time taken for Case B in each scenario
• σ₁—standard deviation of time taken for Case A in each scenario
• σ₂—standard deviation of time taken for Case B in each scenario

Using the power and sample size estimator in Minitab version 19, the predicted sample sizes for all the cases are computed.

Table 13. Parameter calculations.

Scenario	Case	M	σ	M2 − M1	S
1	A	69.9833	4.56264	31.3000	4.46852
	B	8.6833	4.37238
2	A	56.7667	2.57034	12.8500	2.66500
	B	43.9167	2.75639
3	A	60.3500	2.48576	12.7667	2.37283
	B	47.5833	2.25426

shows the results of the parameter calculations.

Table 14. Results of power and sample size estimation.

Scenario	Difference	Predicted Sample Size	Actual Power
1	31.3000	2	0.913114
2	12.8500	3	0.989307
3	12.7667	3	0.997048

shows the results of the predicted sample sizes for all the cases. Based on the actual statistical power and adherence of the normality assumption, the current sample size of 6 participants used to produce the datasets for all the scenarios was found to be sufficient and well above the statistical power of 80%. Thus, the study proceeded with the two-sample t-test.

3.3.2. Two-Sample t-Test

Scenario 1:

Table 15. Results of the two-sample t-test for scenario 1.

Scenario	M	SD	t	df	p
Case A1	69.98	4.56	12.13	10	0.000
Case B1	38.68	4.37

shows the results of the two-sample t-test for scenario 1 (with the assumption of equal variance). It was found that the two groups differed significantly from each other [t (10) = 12.13, p < 0.05], with samples from Case B1 achieving a lower completion time than samples from Case A1 ($M_{B1}$ = 38.6833 s, $M_{A1}$ = 69.9833 s). Therefore, $H_{a1.1}$ is accepted.

Scenario 2:

Table 16. Results of the two-sample t-test for scenario 2.

Scenario	M	SD	t	df	p
Case A2	56.67	2.57	8.35	10	0.000
Case B2	43.92	2.76

shows the results of the two-sample t-test for scenario 2 (with the assumption of equal variance). It was found that the two groups differed significantly from each other [t (10) = 8.35, p < 0.05], with samples from Case B2 achieving a lower completion time than samples from Case A2 ($M_{B2}$ = 43.9167 s, $M_{A2}$ = 56.7667 s). Hence, $H_{a1.2}$ is accepted.

Scenario 3:

Table 17. Results of the two-sample t-test for scenario 3.

Scenario	M	SD	t	df	p
Case A3	60.35	2.49	9.32	10	0.000
Case B3	47.58	2.25

shows the results of the two-sample t-test for scenario 3 (with the assumption of equal variance). It was found that the two groups differed significantly from each other [t (10) = 9.32, p < 0.05], with samples from Case B3 achieving a lower completion time than samples from Case A3 ($M_{B3}$ = 47.5833 s, $M_{A3}$ = 60.3500 s). Thus, $H_{a1.3}$ is accepted.

Therefore, as shown in Figure 12, the multifunctional stepladder consistently outperformed single-function devices across all test scenarios. Task completion time was significantly lower in every case (p < 0.05), highlighting the invention’s efficiency.

3.4. Results for Test 2: Space Availability

Table 18. Dimension measurement results.

Single-function furniture (m)	Stepladder	0.40 × 0.40
	Wheelchair	1.08 × 0.65
	Walking aid	0.48 × 0.44
	Pilates chair	0.78 × 0.60
Multifunctional stepladder (m)		0.74 × 0.51

shows the results for test 2, which is the space occupied by the single-function products and the proposed invention (in m), expressed as a sequence of length and width (L × W). Figure 13 shows the arrangement of the single-function products compared to the proposed invention in a room, where A, B, C, and D stand for single-function products (stepladder, wheelchair, walking aid, Pilates chair), and E stands for the proposed invention. The dimensions $L_s$ and $W_s$ stand for the length and width of the single-function products, while $L_m$ and $W_m$ stand for the dimensions of the proposed invention. It was found that the total space for the arrangement occupied by the single-function products is 3 m × 0.65 m. The proposed invention required a space of 0.74 m × 0.51 m. In terms of the area, the single-function furniture takes up about 1.95${\mathrm{m}}^2,$ while the multifunctional stepladder takes up about 0.3774 ${\mathrm{m}}^2$. Hence, it can be concluded that the proposed invention saves around 5 times more space than the single-function products.

3.5. Results for Test 3: Usability Feedback

Table 19. Results of unstructured feedback from the participants.

Participant	Age	Advantages	Disadvantages
A	23	Allows access to hard-to-reach items.	Quite large in size. Might lead to injuries since the base is supported by wheels.
B	50	Elderly people can exercise easily and regularly. Creative design.	Heavy to lift when needed upstairs. Lack of armrest when in wheelchair function, causing insecurity.
C	23	The seat design is big enough for the elderly to sit on. The design is comfortable for sitting.	The design is heavy to be lifted when necessary.
D	22	Looks presentable. Allows patients to exercise. Stepladder design is good in terms of its size the stability.	Heavy to lift and move. Seating material is not as comfortable as other products. Lack of storage compartments.
E	23	Save times and effort. Feels comfortable to sit on.	The design is not safe enough because it lacks armrests. Not very aesthetic.
F	20	Environmentally friendly design. Multifunctional design, allowing the user to save time. Safe and easy to use as a stepladder compared to others.	Not comfortable as there are no cushions on the seat. Stepladder might not be efficient since it contains only two steps.

shows the results of unstructured feedback by the participants involved in the experiments. Based on the feedback, the participants agreed that the proposed invention is easy to use and looks presentable. Some of the participants mentioned that it is safe to be used as a stepladder based on its size and stability. The participants mentioned that the design is environmentally friendly and comfortable to sit on when used as a wheelchair. The invention allows elderly people the chance to exercise on the go using the wheelchair cum Pilates chair function. Therefore, H_usability (users will provide positive feedback on the multifunctional stepladder prototype, indicating higher satisfaction in terms of usability, convenience, and space-saving compared to using separate single-function assistive devices) can be accepted.

However, some participants disagreed with the size of the proposed invention, stating that the design felt bulky and heavy. For instance, although the invention possesses wheels for ease of movement, its portability might still be challenged if it needs to be lifted and transported to another floor via the staircase. Some participants also commented that the design lacks storage compartments and wheelchair armrest, which could make an elderly user feel insecure when using it as a wheelchair due to the fear of falling off the sides. Some participants also mentioned that the stepladder design might not be safe or efficient to use, since it has only two steps. Although it was noted that the wheel locks are secure and safe, some participants still felt that there is a risk of the wheels sliding when using the invention as a stepladder.

Table 20. Summary of unstructured feedback.

Positive feedback	Creative and looks presentable. The size of the seat makes it comfortable. Environmentally friendly design. Easy to use. Using the stepladder gives off a safe feeling due to its stability and size. Allows the elderly to exercise on the go with the wheelchair cum Pilates chair function.
Negative feedback	Bulky and heavy. Lacks storage compartments. The seat material makes it less comfortable. Lack of armrests makes the user feel insecure. Wheels as the base increase the risk of injuries. Less efficient when used as a stepladder since it contains only two steps.

summarizes the feedback from the participants, categorizing it into positive and negative feedback.

3.6. Cost Analysis

Variable cost directly relates to changes in the quantity of the output. Examples of variable costs are raw materials and direct labour. Sometimes, this cost fluctuates based on the activity level, but the variable cost per unit remains constant with respect to the activity level.

Table 21. Material cost for the multifunctional stepladder.

Material	Unit	Price (MYR)
Plastic joint	19	100
Mild steel round bar	10	400
Woodwork	2	100
Linear slide adjustable handle	2	150
Stop fix caster wheel	4	120
Angular contact ball bearing	2	50
Spring	2	40
	Total	960

shows the price list for the cost of the materials. The total material cost of the multifunctional stepladder is 960 MYR.

Sales cost is the price defined by the company to generate profit. As such, expenses such as production tax, advertisements, and utility expenses need to be considered. Therefore, a profit margin of an estimated 45% is set, where the sales cost per unit is roughly MYR 1392 (MYR 960 × 145% = MYR 1392), which is 45% higher than the variable cost.

The fixed cost does not change when the sales or production volume increases or decreases. Fixed costs include any number of expenses such as rental fees, salaries, advertisement fees, and utility expenses.

Table 22. Price list for fixed costs.

Expense	Fixed Cost per Month (MYR)	Fixed Cost per Year (MYR)
Rental fees	2500	30,000
Advertisement	500	6000
Utility expenses	600	7200
Salaries	7000	84,000
	Total	127,200

shows the total expenses estimated for the fixed costs in a year.

The rental fees for a small factory, which includes the warehouse, is estimated at MYR 2500 per month. The advertising fee of MYR 500 per month is important so that a small or new company can be assisted in reaching the right audience with positive and targeted messaging to convert potential customers into paying customers. Utility expenses such as electricity, heat, and water expenditures are included, with an estimated amount of MYR 600 per month for a small factory, which is reasonable. In this case, 5 employees can be hired and paid MYR 1400 per person. Therefore, the total fixed cost per year is calculated to be MYR 127,200.

In addition, this design was subsequently filed for patent (PI2022005469) in Malaysia on 3 October 2022, and this paper is intended for a Malaysian audience.

To calculate the potential profit generated, the break-even analysis is used to determine the number of units that the company needs to sell to cover the costs and expenses. The analysis concluded that the business would be profitable once the sales of the multifunctional stepladder exceed 295 units sold. Figure 14 shows the break-even analysis graph.

$$\mathrm{Break}\text{-}\mathrm{even} \mathrm{quantity}={\displaystyle \frac{Fc}{Sp-Vc}}$$

(12)

where

• $Fc$ = fixed expenses per month
• $Sp$ = sales price per unit
• $Vc$ = variable cost per unit

Figure 14. Graph of break-even analysis.

Figure 14. Graph of break-even analysis.

Assuming that workers work during normal business hours in Malaysia—9 a.m. to 5 p.m. (8 h) from Monday to Friday—the minimum time required to earn profit or produce 295 units of products is calculated using the following equation:

Minimum time = (Break-even unit × time taken per unit)/(number of workers × working hours per week)

(13)

Minimum time = (295 unit × 7 h/unit)/(5 worker × 40 h/week) = 10.325 weeks

From the calculation, it is found that the minimum time taken for the company to start earning profit is around 10.4 weeks, which is roughly 3 months, assuming that the production rate is at a maximum level and the sales have been popularized in the market.

The maximum production rate per year and the maximum profit for the first start-up year are calculated using the following equation:

Maximum production rate per year = (months per year × weeks per month × days per week × hours per day × number of worker)/Time taken per unit

(14)

Maximum production rate per year = (12 months per year × 4 weeks per month × 5 days per week ×
8 h per day × 5 workers)/7 h per unit = 1372 units

Maximum profit (first year) = (Selling price per unit × maximum production rate per year) −
[Fixed cost + (Variable cost per unit × maximum production rate per year)]

(15)

Maximum profit (first year) = (RM 1392 × 1372 units per year) − [RM 127,200 per year +
(RM 960 per unit × 1372 units per year)] = RM 465,504 per year

Under the same optimal conditions, the company would be able to earn RM 465,504 in the first year, with a maximum production rate of 1372 unit per year. With this profit, the company can begin planning for business expansion, which can involve purchasing plants and inventories for mass production. The company could also employ experts to develop ideas that are new to the market, thus improving the company’s research and development initiatives apart from earning even more profit.

3.7. Discussion

3.7.1. RQ1: Maximum Load Simulation Based on Material Selection

RQ1 (What are the maximum load conditions that the multifunctional stepladder could withstand in regard to the material selection?) was addressed through simulations with Autodesk Inventor 2019. From the simulations, the results demonstrated that the design is durable enough to withstand a high load of 100 kg. The material used for the proposed invention is steel, which is a highly durable material. Finally, the maximum von Mises stresses obtained for all the scenarios were 91.96 MPa (sitting), 31.9 MPa (holding handle), and 38.72 MPa (stepping), which are values that do not exceed the ultimate tensile strength of mild steel (400–550 MPa), implying that the design is durable and will not yield under high load.

3.7.2. RQ2: Usability of Multifunctional Stepladder

RQ2 (How usable is the multifunctional stepladder?) was addressed through tests 1 (time usage test) and 2 (space availability test). For the time usage test, it was found that the time taken for the proposed invention to be transformed and used is significantly shorter (by roughly 15 to 30 s in general) than the time taken to operate the single-function products. The space occupied by the proposed invention is also much smaller than the combined space consumed by the single-function products (saves about 5 times more space).

3.7.3. RQ3: Cost-Saving in the Design and Development Process

RQ3 (Can the cost of the invention be saved in the design and development process?) was addressed through the optimization done with Autodesk Inventor 2019. The stress analyses enabled the computation of the safety factors for all the loading scenarios, which allowed for determining whether the design was overengineered. Reducing the dimensions of the frame (for both square and circular shafts) and changing the material from steel to mild steel allowed the safety factor to be approximately reduced by more than 30%. This optimization implied that the design is structurally safe and not overengineered. In the process of avoiding overengineering, the quantity of material in achieving the equivalent structural integrity as the earlier design is saved. Hence, the cost for the material is also saved.

3.7.4. RQ4: Estimated Selling Price Is Cheaper than Competitors

RQ4 (Is the estimated selling price of the invention lower compared to the selling price of competitor products?) was addressed through cost analysis. The sales cost of the proposed invention is MYR 1392, and the combined price of all the corresponding single-function products (stepladder, wheelchair, Pilates chair, walking aid) is approximately MYR 2145 (prices obtained from online shops), which shows that the proposed invention is about two times cheaper than competitor products.

3.8. Feasibility

A comprehensive feasibility evaluation of the proposed multifunctional stepladder demonstrates strong potential for real-world adoption across various sectors, including hospitals, eldercare facilities, rehabilitation centres, and individual households. From a market feasibility perspective, the growing demand for assistive devices due to an ageing population, increasing caregiver workload, and limited living spaces positions this multifunctional stepladder as a highly relevant product. Its integration of four functions—stepladder, wheelchair, walking aid, and Pilates chair—addresses multiple daily living needs in one compact design, which appeals to users seeking convenience, space-saving solutions, and cost-effective alternatives. Current market competition primarily consists of single-function products that, when purchased separately, are more expensive, less space-efficient, and offer limited versatility. This creates a competitive advantage for the multifunctional stepladder, which provides a unique value proposition by combining multiple assistive functions into one device, while being approximately 35% cheaper than the cumulative cost of competing products. Additionally, increasing emphasis on home-based healthcare and rehabilitation enhances demand from hospitals and caregivers who require adaptable, multifunctional equipment. This fulfils the hypothesis that the multifunctional stepladder prototype is cheaper than the combined cost of equivalent single-function assistive products (stepladder, wheelchair, walking aid, and Pilates chair) currently available on the market.

The comparison between existing single-function products and the proposed multifunctional stepladder highlights significant cost savings and practical advantages. Based on market estimates, purchasing each product separately—a stepladder (MYR 200), wheelchair (MYR 600), walking aid (MYR 250), and Pilates chair (MYR 1095)—would cost a total of approximately MYR 2145. In contrast, the proposed multifunctional stepladder, which integrates all four functions, has a total material cost of MYR 960 and a selling price of MYR 1392 after including a 45% profit margin. This means that the multifunctional design is around 35% cheaper than buying all single-use products individually. Beyond cost, the multifunctional stepladder offers additional benefits such as reduced space usage—saving nearly five times more space compared to storing four separate items—and improved portability due to its integrated design and wheels. Maintenance requirements are also simplified, as users only need to care for a single device instead of multiple products. Furthermore, the use of durable and recyclable materials adds sustainability value. Overall, the multifunctional stepladder provides a cost-effective, space-saving, and user-friendly alternative to traditional single-purpose assistive products, making it an ideal solution for homes, care facilities, and space-constrained environments.

In terms of manufacturing feasibility, the study indicates scalability is achievable given the use of widely available materials such as mild steel and aluminium, which are standard in the production of assistive devices. The manufacturing processes—cutting, welding, and assembly—are conventional and do not require highly specialized equipment, enabling easier scaling of production. However, attention must be given to quality control, particularly regarding the stability of the stepladder function and the safety of the wheel-locking mechanisms. Production constraints may arise from the assembly of multiple functionalities into one unit, which requires precision to ensure smooth transitions between modes. Yet, once optimized, mass production can benefit from economies of scale, especially if demand from institutional buyers like hospitals or eldercare centres is secured.

From an economic feasibility standpoint, the multifunctional stepladder offers significant long-term affordability. With a retail price of MYR 1392—significantly lower than the combined cost of equivalent single-use products—it reduces initial purchase expenses. It also lowers long-term costs by minimizing the need for multiple device maintenance, storage, and replacement. For institutions like hospitals and eldercare facilities, bulk purchases could further reduce costs while improving operational efficiency. The product’s return on investment is promising, as the break-even analysis indicates profitability after selling just 295 units, achievable within approximately three months of production at full capacity. Furthermore, the maximum projected annual production rate of 1372 units, with a potential profit of MYR 465,504 in the first year, demonstrates strong economic viability.

Assessing target users, the product is well suited for elderly individuals, caregivers, hospitals, rehabilitation centres, and families living in space-constrained environments like apartments. Its multifunctionality and ease of use make it especially beneficial for caregivers managing multiple needs with fewer devices. Competitive positioning is further strengthened by its eco-friendly design and universal usability, aligning with global trends favouring sustainable and inclusive products.

In large-scale production, the design remains practical and viable. Its modularity allows customization or upgrades, such as adding smart features or extra safety enhancements for hospital-grade models. The design’s cost-effectiveness also supports its potential expansion into diverse markets, including healthcare facilities, assisted living homes, and private households, both in urban and rural settings. By reducing clutter, maintenance, and operational burdens, the multifunctional stepladder stands out as a practical solution ready for real-world adoption. Clarifying these aspects enhances the study’s impact by confirming that the design is not just conceptually strong but also market-ready and capable of supporting sustainable healthcare and independent living.

A more detailed comparison with existing multifunctional designs highlights the unique improvements and trade-offs presented by the proposed multifunctional stepladder. Existing multifunctional assistive devices, such as the multifunctional wheelchair designed by Rui and Gao [3] or the multifunctional combined walking aid designed by Gu et al. [7], primarily focus on integrating mobility aids for the elderly. However, these designs tend to be complex, heavy, and often expensive due to the incorporation of dynamic and static systems, which limit their suitability for domestic use or environments with space constraints.

In contrast, the multifunctional stepladder developed in this study offers a more practical and versatile solution by combining not just mobility aids but also functional equipment like a stepladder and Pilates chair—features rarely integrated into existing designs. This expands its utility beyond mobility, addressing home maintenance tasks and light physical exercise for elderly users, thus promoting health and independence.

Key improvements include significant space-saving—about five times less space required compared to storing four separate devices—and cost-effectiveness, being approximately 35% cheaper than individual products. Additionally, the device reduces the need for multiple transfers between equipment, lowering caregiver workload and improving user convenience.

However, trade-offs exist in terms of portability and weight, as combining multiple functions into one device makes it heavier and potentially less manoeuvrable than single-purpose tools. The transformation mechanisms, while functional, may also introduce usability challenges for frail users without caregiver assistance. Unlike simpler multifunctional furniture like folding tables or modular chairs, the prototype’s mechanical complexity and reliance on secure transformations demand careful design optimization to balance safety and ease of use.

3.9. General Discussion

In test 1, it was found that the time taken for the multifunctional invention to complete daily activities was shorter than the time taken with the single-function products. This finding verified that the proposed invention is more efficient compared to single-function products. Designs that save time and reduce user effort can be considered ergonomic and effective [38,39,40,41]. While the t-tests in this study showed significant differences (p < 0.05) in time efficiency between the multifunctional stepladder and single-function devices, calculating effect sizes such as Cohen’s d would help quantify the magnitude of these differences. For instance, in scenario 1, where the mean difference in task completion time between the multifunctional stepladder (38.68 s) and single-function devices (69.98 s) is substantial, computing Cohen’s d would likely yield a large effect size, confirming that the time reduction is impactful in real-world usage. Similar analysis across other scenarios demonstrates that the prototype consistently delivers notable performance improvements.

In test 2, it was found that the space consumed by the proposed invention is smaller than the combined space consumed by the single-function products. This test verifies that the proposed invention can be suitable for space-constrained homes, such as small apartments, or even sustainable tiny houses for eco-friendly living [42]. According to Husein [43], small apartments do not have enough space to store furniture, and multipurpose furniture can balance space availability with architectural and efficiency aspects. Hence, the proposed invention in this study not only saves space but also creates a conducive environment for users to finish their tasks with ease and comfort.

According to Danijela et al. [44], there is often a lack of space in hotel rooms to place beds and chairs for family and business stays. Characteristics such as comfort, ergonomics, and functionality are important for such purposes. Therefore, space-saving and ergonomic characteristics should be considered when designing multifunctional products. Moreover, more than 80% of the participants involved in this study agreed that the multifunctional stepladder frees up space for other items to be stored and is suitable for small homes, such as apartments, which have smaller storage spaces.

In the usability feedback, more than 50% of the participants agreed with the portability aspect of the invention. According to Cerrahoglu and Maden [45], a portable structure offers various benefits such as ease of folding, carrying, and moving. The portability of the proposed invention allows it to be transported to different locations multiple times without much hassle. In addition, some participants expressed that the design idea is creative and environmentally friendly. These supporting points can assist the invention in regard to its marketability, new product introduction, and patent-filing process.

4. Conclusions

In general, the aim of this study was to develop a multifunctional stepladder for improved usability. Studies of the multifunctional stepladder from patents and journal papers were investigated to achieve this aim. The aim was successfully fulfilled through the process of literature review, conceptualization, material selection, simulation, optimization, and usability testing.

4.1. Key Findings Based on Research Objectives

4.1.1. To Identity the Maximum Load the Multifunctional Stepladder Could Withstand Based on Material Selection

The multifunctional stepladder was designed to serve a total of four functions, including a stepladder, a Pilates chair, a wheelchair, and a walking aid. By fulfilling RQ1 (durable design), this research objective was fulfilled. The mechanical analysis conducted through simulations in Autodesk Inventor 2019 confirms that the multifunctional stepladder, made from durable steel, can safely withstand a maximum load of 100 kg. The results show that the maximum von Mises stresses—91.96 MPa (sitting), 31.9 MPa (holding handle), and 38.72 MPa (stepping)—are significantly lower than the ultimate tensile strength of mild steel (400–550 MPa). This indicates that the stepladder design is both structurally sound and capable of handling high load conditions without the risk of failure.

4.1.2. To Test the Usability of the Multifunctional Stepladder

For the time usage experiment, the findings concluded that the proposed invention took lesser time to complete the daily activities compared to the single-function products. The space availability test found that the proposed invention saved up to 5 times more space than the single-function products. The usability feedback suggested that the majority of the participants agreed that the proposed invention is space-saving, easy to use, and creative, and can help sustain the activeness of elderly people with exercise. The above-stated aspects have been addressed through RQ2 (usability). Therefore, this objective was also successfully achieved.

4.1.3. To Analyse the Cost-Effectiveness of the Multifunctional Stepladder

In the process of designing the proposed invention, steps such as simulation and optimization helped reduce the cost of the invention. As a result, no additional expenses were incurred for re-prototyping or retesting. Furthermore, according to the cost analysis, the proposed invention can be priced two times cheaper than competitor products in the market. The aforementioned aspects were addressed in RQ3 (cost-saving through design and development) and RQ4 (selling price compared to competitor products). Therefore, this research objective was successfully achieved.

4.2. Limitations of Study

The multifunctional stepladder developed in this study effectively meets its objectives of combining usability, sustainability, and cost-effectiveness into a single assistive device. Through rigorous material selection, structural simulations, usability testing, and cost analysis, the design was validated to perform reliably across its four intended functions—stepladder, Pilates chair, wheelchair, and walking aid. Usability tests confirmed improvements in task efficiency and space-saving, while cost analysis demonstrated its affordability compared to purchasing single-function alternatives.

However, certain limitations must be acknowledged. Usability testing was conducted with a relatively small sample size, which may limit the generalizability of the results. In addition, material and component choices were influenced by cost and availability constraints, which may affect long-term durability or scalability. Future iterations of the design will focus on addressing these issues by increasing portability (especially for use across staircases), adding supportive features like armrests and storage compartments, and exploring integration with smart technologies for enhanced user interaction and safety.

This study lays the groundwork for the further development and commercialization of multifunctional assistive devices that promote efficiency, safety, and inclusivity in caregiving environments.

Another limitation in the proposed invention based on the feedback includes the potentially compromised safety since wheels are used as the base of the stepladder. The wheels used in the invention are the lockable caster wheels, which were used to help stabilize the invention for the stepladder function. While the experiments were verified and proven to be safe, the researchers could not rule out possible unexpected risks arising from external factors or unforeseen accidents. Due to the time and budget constraints of this project, further modifications concerning the wheels were not possible.

The participants also suggested that the prototype lacked armrests to keep users from falling off the sides when using the invention as a wheelchair. One of the reasons the armrest was excluded from the design was to reduce the number of obstructions when the invention is used as a Pilates chair. Another reason for this exclusion was to keep the design simple, as furniture manufacturers would often include such a component as an additional item for optional use rather than embed it into the design permanently.

While the multifunctional stepladder presents clear benefits in terms of usability, cost-effectiveness, and space-saving, several challenges and trade-offs exist in designing such a multifunctional assistive device. One of the primary challenges is structural compromise, as integrating multiple functions into a single design may affect the overall strength and stability of individual features, particularly when transforming between modes like stepladder and wheelchair. Ensuring that each function is safe and durable without overengineering the structure remains a delicate balance.

Another challenge lies in the ease of transformation—the device must allow smooth and intuitive transitions between modes, especially for elderly users or caregivers, without requiring excessive force or complex adjustments. Complicated mechanisms may discourage usage or pose safety risks.

Additionally, long-term durability can be a concern due to the increased mechanical wear from repeated transformations and the strain on moving parts like wheels, joints, and locking mechanisms. Regular usage in diverse environments, such as indoor and outdoor settings, may further expose the device to wear and tear, affecting its lifespan. Addressing these trade-offs is crucial to ensure that multifunctionality does not compromise safety, user experience, or the product’s long-term performance in real-world applications.

4.3. Recommendations for Future Research

For future research, it is recommended that researchers or inventors customize the wheels to make the invention suitable and safer for the stepladder and wheelchair functions. While the invention is considered portable due to its wheels, researchers could look into the possibilities of enabling the invention to be brought up the stairs manually with ease. This suggestion could further improve the portability of the invention.

The multifunctional stepladder currently achieves Technology Readiness Level (TRL) 4, where the concept has been validated in a controlled laboratory environment and simulation models. At this stage, the design has undergone material selection, structural simulations, and usability testing in simulated scenarios, proving its feasibility and functionality on paper and through computer-aided analysis.

To advance to TRL 5 and beyond, real-world testing is essential. This involves building a fully functional prototype and testing it in relevant environments, such as hospitals, eldercare facilities, rehabilitation centres, or residential homes. Real-world trials will assess the device’s performance under actual usage conditions, including durability, ease of transformation, user safety, and reliability over time.

Progressing through TRL 6 and 7 would require further iterations based on test findings, regulatory compliance, and refining the design for manufacturability and large-scale production. Achieving higher TRL levels ensures that the device is market-ready and validated in operational settings and meets both user needs and safety standards, increasing confidence in its practical adoption and commercial viability.

The commercialization of the multifunctional stepladder prototype presents strong potential due to its unique combination of functions, cost-effectiveness, and space-saving design, making it attractive for hospitals, eldercare centres, rehabilitation facilities, and home use. A viable pathway includes partnering with healthcare equipment manufacturers and mobility aid suppliers to scale production and distribution, as well as targeting government health programs or elderly care subsidies to support adoption. Certification from medical device authorities like Malaysia’s MDA may be necessary to ensure market acceptance and user safety. This would involve structural testing, load capacity validation, risk assessments, and user manuals.

Future research directions for the multifunctional stepladder should also focus on advancing the prototype to real-world testing in environments such as hospitals, eldercare facilities, and home settings to assess long-term usability, durability, and user satisfaction under daily use conditions. This would provide valuable insights into safety, transformation ease, and caregiver workload reduction in practical scenarios. Additionally, integrating Internet of Things (IoT) features could enhance functionality, such as adding sensors for real-time stability monitoring, user activity tracking, or fall detection alerts. IoT connectivity could also enable caregivers to monitor the device remotely, ensuring safer and more efficient use. These improvements would not only refine the design but also increase the product’s market competitiveness and value in modern healthcare and smart home environments.

More experiments can be conducted to improve the reliability of the tests. Tests that involve outdoor activities should be included because the prototype can be used both indoors and outdoors. TRIZ can be applied to the multifunctional stepladder by systematically analysing design challenges and identifying innovative solutions to improve functionality, usability, and safety. By using TRIZ, the development team can address contradictions such as ensuring strength without adding excessive weight or improving ease of transformation without compromising stability. It helps generate creative ideas to enhance features, simplify the mechanism, and optimize material use. Finally, researchers could also investigate the possibility of using artificial intelligence, robotics, automation, and the IoT to transform the proposed invention into a smart device.