Portable VR Welding Simulator

Abstract

In many industries, there is a continuous high demand for skilled welders. Practical training in welding is cost- and time-intensive. To reduce this problem, VR welding simulators have been developed in recent years. They vary in terms of portability, hardware and software components, and functionalities. In this paper, a VR simulator to support practical training in MIG/MAG welding, as a highly portable and affordable solution, is presented. Its only hardware components are an off-the-shelf mobile VR set, a welding torch, and welding coupons that are manufactured using the FDM 3D printing method. The software part is accessed and used via an Internet browser. An important feature of the simulator is also the possibility to differ immersion in the working environment while carrying out virtual welding, which makes the solution also usable for users prone to cybersickness. The VR welding simulator was refined based on feedback obtained during pilot tests. The test participants found it a useful aid for welders’ training, which justifies further work on its development and integration into the teaching of welding in educational and training units.

1. Introduction

In the construction and manufacturing sectors, there is a continuous demand for skilled welders. As [1] indicates, in 2022 in Europe, a shortage in this occupation was reported by 17 out of 29 European countries, and welders were among the most needed professions (ranked third). Forecasts regarding demand for welders in Poland in 2024 indicate job vacancies in almost the whole country [2]. Thus, welding remains an important occupation to be covered by the education and training sector.

A professional welder has knowledge and skills that enable them to carry out activities in a correct and safe way. These are acquired by a mix of classroom training and hands-on training [3,4]. Whitney and Stephens [5] indicate the following training principles for welders’ training: (1) students can practice relevant skills; (2) students’ performance is assessed; and (3) students obtain feedback during and after training.

Due to the nature of welding, the traditional training of welders is time-consuming and expensive [6]. Welding is a process requiring specialist technical equipment, material (metal, natural gas, welding wire, and consumable or non-consumable electrode rods), and energy. Carrying out welding is a precise and difficult skill, the mastering of which requires complex theoretical knowledge and many practical exercises (hands-on learning) under the guidance and supervision of a trainer who demonstrates, instructs, observes, and provides feedback and verifies the correctness of a trainee’s actions and the created weld. Practical demonstrations made by the trainer and welding exercises repeated by the trainee until they can consistently create high-quality welds contribute to the training costs because the joined (welded) elements become waste, and for each trainee, a trainer’s working hours must be spent. The safety of trainees also has to be secured. Welders face a number of risks while working, e.g., skin burns, eye damage, hearing loss, inhaling toxic welding fumes and gasses, and electrocution, and thus they have to wear the appropriate personal protective equipment [7,8,9,10]. Additionally, for practical training, a specialized space or workshop, with all the necessary equipment and infrastructure, has to be prepared.

During training, a welder has to learn to move the welding torch in the correct way in terms of speed, position (angles towards the joined elements and the weld being created), path, and distance and, at the same time, observe (“read”) the welding pool [5,11,12]. The continuous evaluation of the correctness of these parameters is difficult, especially for beginners. This ability comes with practice. The trainer can either observe a trainee’s posture or the weld being created by them. When the trainer wants to observe the creation of a weld by a trainee, they have to wear a helmet, which makes it impossible to observe the trainee’s posture at the same time. All of these conditions contribute to the time spent on practical training by a trainer and a trainee [13].

For years, the development of ICT (information and communications technology) has offered varied opportunities to support welders’ training, which has resulted, among other things, in the development of simulators based on VR (virtual reality) [4,14,15,16,17,18,19]. In Musawel’s PhD thesis, a literature review covers the attempts and achievements in the development of ICT-based solutions for welders’ training, starting with patents of welding simulators registered in the 1970s [19]. Examples of pioneering works in the development of simulators for welders’ training are also presented in [20,21].

VR is considered useful for the delivery of practical training as it enables us to reduce or overcome the problems encountered when carrying out training in a traditional way, which also regards training in welding [5,13,22,23,24,25,26,27,28,29]. Stone et al. [30] raise that in the case of difficult welding tasks, training with the use of a VR welding simulator has to be supplemented with real-world training.

VR makes it possible to replicate real training stands and/or work stands and make them available for trainees who can carry out activities and acquire practical skills. The training is carried out in safe conditions, where a trainee is not exposed to hazards that are present or might occur in real-life conditions. A trainee can repeat an activity as many times as necessary with no fear of the consequences of errors [10,22,23].

VR solutions offer a varied degree of immersion, which affects the possibilities they give for practical training in different professions. Non-immersive VR is delivered via a screen (or screens) on which a computer-generated world is displayed and a trainee takes actions there with the use of input devices, e.g., a mouse, a keyboard, or a joystick. In semi-immersive VR, a user’s immersion in the computer-generated world is partial, as in the case of a flight simulator. A trainee interacts with the virtual world but, at the same time, remains fully aware of the physical environment around them. In high-immersive VR solutions (also called I-VR [31]), users, equipped with head-mounted displays (HMDs, commonly called VR goggles) and haptic controllers, feel present in the computer-generated world in which they can move around and interact [31,32,33,34,35,36]. For this type of VR, integration, interactivity, and imagination are indicated as features important in the context of its applicability for teaching [10,37]. Immersion is one of the factors that contributes to cybersickness, which might limit the time of training sessions with the use of high-immersive VR [38,39,40].

It should be noted that parallel to VR welding simulators, simulators based on augmented reality (AR) are also developed as a solution to overcome problems indicated by traditional welders’ training [6,41,42].

The authors of this paper propose a VR welding simulator which was developed by combining their competencies in 3D modeling and design, 3D printing, the development of materials with the use of VR and WebXR, and programming. For design-stage purposes, a literature review covering ideas and achievements in the creation of VR welding simulators was conducted.

The developed VR welding simulator is a portable and affordable solution, the use of which requires an off-the-shelf mobile VR set with Internet access and optionally (however, recommended) 3D-printed components used instead of a real welding torch and welding coupons. Pilot tests suggested that the solution could be useful for welders’ training and was worth further development.

2. VR Welding Simulators

VR simulators are used to teach one or more welding methods, e.g., SMAW (shielded metal arc welding), MIG (metal inert gas), and TIG (tungsten inert gas). The continuous development of applicable hardware and software and their increasing affordability contribute to the intensified research and development work on new VR welding simulators, carried out both by companies and by academics. Consequently, VR simulators and their application in the education and training of welders are the subject of many scientific publications.

In a literature review presented in [19], both registered patents and papers on VR hardware and software used for welders’ training are included, covering the period from 2003 to 2012.

Heibel et al. [4], based on a literature review covering peer-reviewed publications regarding VR-aided training in welding published between 2012 and 2022, proposed the following classification of topic themes covered by them: 1. Comparison of Approaches—concerns articles in which VR-aided training and other training methods applied for welders are compared; 2. VR as a Teaching Tool—regards articles in which several aspects of the implementation of VR in welders’ training are discussed; 3. System Development—refers to articles in which the creation of VR solutions for training in welding is described; and 4. System Testing—regards articles in which different findings from research on the use of VR training solutions are shared. For each of the collected articles (18 in total), one or more of these topics were identified, and for each topic, the main ideas and findings presented in the assigned publications were briefly described. The findings of the research are, among others, as follows: (1) the application of a VR welding system effectively supports teaching and self-learning of welders; however, it cannot replace welding operations; (2) familiarizing with VR may be challenging, both for teachers and for trainers, but once the ability to use VR is acquired, it is appreciated as a training tool; and (3) the postures taken by trainees while carrying out a welding task in the VR environment must reflect those in the real environment. Based on the literature review, Heibel et al. identified research gaps and indicated themes for further investigation on VR welding systems, e.g., their integration in welders’ training and providing a trainee with feedback and cues while carrying out virtual welding.

Chan et al. [6] conducted an extensive literature review covering scientific papers in which, among others, the following aspects regarding VR welding simulators are presented: (1) their effectiveness as a training aid, also compared to other solutions; (2) their structure, operation, and functions; and (3) the users’ perceptions and opinions.

A thorough review of welding simulators, including those that employ VR, was conducted by Whitney and Stephens [5]. In the research, both commercialized solutions and those not commercially available were analyzed and discussed, taking into account their design, use, and effectiveness. Knoke and Thoben [43], in their study, identified welding simulators, including VR-based solutions, and classified them taking into account their human–machine interface design.

Descriptions of VR welding simulators presented in scientific papers and delivered by providers of commercialized solutions show a variety of ideas and configurations with regards to the systems’ structure and operation. Further, comments on these refer to solutions based on mature VR, developed in the past several years.

There are two main types of components in a VR welding simulator: hardware and software. The latter is a software tool with which a user interacts (to select a welding task, to start the task, etc.). It will be called a “simulator software tool” hereafter. VR welding simulators are aimed at either supporting both learning to set up a welding machine and learning to create a weld, or they are limited to the latter, which affects what components they have.

In many VR welding simulators, there is a component that looks like an imitation of a welding machine or resembles it; however, the setting-up operations are usually carried out on a dedicated screen in the simulator software tool. A component directly related to weld creation is a welding torch (one or more, depending on the simulator), which is usually a replica. In many solutions, a trainee wears VR goggles through which they can see the working environment and the welding process being carried out (its simulation), as well as additional information regarding the correctness of the operation. This content may also be displayed on a screen, either in addition to viewing it through VR goggles or instead. VR goggles may be a built-in element of a welding helmet. They can also be wireless or connected to a computer with a cable. Welding coupons are another physical component of VR welding simulators. Usually, in VR welding simulators, there is a stand on which to place the welding coupons (on a flat surface or in other positions). Three-dimensional printing is among the methods used for the manufacturing of simulator’s welding torches and welding coupons [44,45].

In the simulator software tool, the main functions are as follows:

• Selection of a welding task to be carried out.
• Showing—in real-time mode—the VR environment in which the welding task is being performed; in the VR scene, a simulation of the weld creation is shown along with immediate feedback on how efficiently the trainee met the required welding parameters and a summing-up report on the trainee’s performance in the task. There might also be an option to select a virtual environment in which the task is carried out, e.g., a construction area, a welding workshop, etc.

In the simulator software tool, there might also be functionalities that expand the simulator into a database training system in which the data regarding trainers, trainees, carried-out tasks, scores obtained, and other factors are collected. Additionally, training materials can be shared through this system.

Developers of VR welding simulators tend to also offer their solutions in portable versions, i.e., simulators that are easy to transport.

To present the possible configurations of VR welding simulators, three examples of real simulators are described below in a concise way, taking into account their main components and functionality.

A GuideWELD^® VR welding simulator [6,10,46] (provided by Realityworks, Inc., Eau Claire, WI, USA) can be used for learning to create welds with MIG and SMAW methods. It consists of the following components: a computer on which the simulator software tool is run and a workstation on which welding coupons are placed and to which a welding torch is connected with a wire. The trainee does not wear VR goggles. Observation of the VR environment is made on the computer monitor. The computer (the unit and the monitor) is organized by the user, meeting the requirements defined by the simulator developer. Before starting a welding task, the users can select between three levels of task difficulty and switch between left-hand mode and right-hand mode. The simulator software tool includes functionalities of a database learning system. Three types of joints are covered by the welding tasks: butt, tee, and lap. The searched resources do not indicate whether (1) the welding coupons can be located in a different way than flat on the workstation or whether (2) a working environment to be displayed in the VR scene can be selected.

A VRTEX^® 360^® Single User Virtual Reality Welding Training Simulator [11,47] (provided by Lincoln Electric, Cleveland, OH, USA) can be used for learning MIG, SMAW, and TIG welding methods. Both the creation of a weld and the setting-up of a weld machine are included. Its components include VR goggles, a touchscreen monitor, welding torches, a computer unit that looks like a replica of a welding machine, welding coupons, and a stand to mount them on. Both the VR goggles and the welding torches are connected to the computer unit. The whole interaction with the simulator software tool takes place via the touchscreen monitor. Both left-handed and right-handed people can use the system. The simulator software tool includes functionalities of a database learning system. Seven different welding coupons are provided, including the following types of joints: butt, tee, and lap. In the welding tasks, the coupons are located in different positions. Regarding the VR scene in which the tasks are carried out, several different welding environments are available. The following VRTEX solutions are also available:

• A “dual” version that enables the carrying out of training independently by two students at the same time—two “single-user” VR simulators have one common computer unit [48].
• A compact, portable version in which the stand is replaced with a smaller component—a pole on which a welding coupon is located that can be mounted to a table; the touchscreen is also located on the table [49].

The authors of [50] presented a simulator for learning three welding methods: SMAW, MIG, and TIG. In this solution, the main hardware elements are welding torches (one for each welding method), plates (mounted on a handler), a computer (laptop), and VR goggles. The plates are attached to a circuit board with IR sensors. No physical or virtual helmet is used by the trainee. The simulator software tool is run on the computer. Visualization of the process includes 3D models of the torch, the plates, and the weld being created, as well as the environment where the work is being carried out (factory or laboratory). The visualization of the process takes place on the VR glasses and on the computer screen. The data regarding the movement and position of the welding torch towards the welded elements are sent to the computer and the welding parameters are displayed in real-time mode. After completion of a welding task, a trainee obtains information about whether the weld joint was created, and in case of success, information about the weld size and parameters is also delivered to them. The VR goggles are connected with a wire to the computer. It is not mentioned whether a selection of left-hand mode is possible. The implementation of the VR welding simulator is presented using an example of a fillet weld created to join two plates in a flat position. It is declared that butt or lap joints can also be covered by the welding tasks, but it is not clearly stated whether (1) the plates can be positioned in other ways or whether (2) welding of pipes or welding of a pipe and a plate can be carried out. The VR scene is limited to basic elements: no virtual working environment imitating the real one is displayed.

3. Materials and Methods

3.1. Assumptions for the VR Welding Simulator

3.1.1. Skills to Be Acquired

The developed VR welding simulator is intended to aid training in MIG/MAG welding (metal inert gas/metal active gas), and its specific aim is to aid acquisition of the ability to move and position a welding torch properly. The mastering of this skill is reflected by meeting the requirements regarding the following parameters during the weld creation: travel speed, travel angle, work angle, and contact-tip-to-work distance (CWTD) [5,11].

Travel speed is how fast a welding torch is moved along the weld path. Travel angle is the angle at which a welding torch is positioned in the horizontal plane, and the work angle regards the positioning of a welding torch in the vertical plane. The CWTD is the distance between the tip of the welding torch and the workpiece. A welder has to both know the correct values of these parameters and be able to meet them during welding operations. The latter requires practical hands-on performance of the welding, which is supported by the VR welding simulator.

3.1.2. Simulator Features

The following features have been established:

• The hardware part of the simulator will be composed of the following:
  • A wireless VR set (mobile VR goggles and controllers);
  • A 3D-printed welding torch;
  • 3D-printed elements to be welded (welding coupons).
• The software part of the simulator will be accessed online-via an Internet browser.
• The system will be expandable (adding welding tasks will be possible).
• Both left-handed and right-handed users will be taken into account.
• Several welding positions will be covered by the tasks.
• The users will obtain information on their performance (the correctness of welding) both during a welding task and after completing it.
• The parameters of the welding process will be correctly set prior to starting the process.
• In addition to full immersion, the user should have an option to be partially immersed while carrying out a welding task. This assumption results from the experience that the developers of the simulator have with the use of the AR mode offered by WebXR.

The 3D-printed components will be optional but recommended. The 3D models of the welding torch and the elements to be welded will be ‘linked’ with the controllers assigned to them. The employment of the 3D-printed components is intended to increase the feeling of carrying out a real welding operation, e.g., the collision of a welding torch and a plate will be not only seen in a simulation but also physically experienced.

3.2. The VR Welding Simulator Structure

The structure of the VR welding simulator, from a user’s perspective, is shown in Figure 1.

The VR welding simulator includes the following tangible components:

• A VR set, i.e., wireless VR goggles and two controllers. In the system, one controller is assigned to the welding torch and the other one to the welding coupon. The assignment depends on whether the system is run in a mode for a right-handed user or a mode for a left-handed user. If one changes the mode, the role of the controllers will be changed as well. The VR set used during the development of the VR welding simulator is shown in Figure 2.

• A 3D-printed customized welding torch (Figure 3a). The original 3D model of a welding torch has been modified to enable adding a holder on which one of the controllers is mounted. The two elements, i.e., the modified welding torch and the holder, were 3D-printed and joined by gluing; the controller serves as a handle to grab and move the welding torch (Figure 3b).

Figure 3. A 3D-printed customized welding torch: (a) single; (b) with a VR controller.

Figure 3. A 3D-printed customized welding torch: (a) single; (b) with a VR controller.

• 3D-printed customized welding coupons (Figure 4). In each, there is additionally a base with a holder on which a VR controller is mounted. The user does not engage with the controller in any way; it is necessary only for the software part of the VR welding simulator. The base (in the form of a flat plate) allows the stable placement of a welding coupon on the work table or allows it to be mounted on a stand in a way that enables the welded elements to be positioned as desired. Thus, the set of customized coupons can be used for the following tasks at all possible positions (flat, horizontal, vertical, and overhead): joining of plates with a butt weld, joining of plates with fillet welds, or joining of pipes with a butt weld.

Figure 4. Three-dimensional printed customized welding coupons, with and without a VR controller: (a) plates, (b) pipes.

Figure 4. Three-dimensional printed customized welding coupons, with and without a VR controller: (a) plates, (b) pipes.

In

Table 1. Welding positions available with the prepared welding coupons.

Jointed Elements	Weld Type	Positions
		PA	PB	PC	PD	PE	PF	PG	PH	PJ
Plates	Butt	Y	-	P	-	P	Y	Y	-	-
	Fillet	P	Y	P	P	P	P	P	-	-
Pipes	Butt	P	-	Y	-	-	-	-	P	P
Pipes and plates	Fillet	N	N	-	N	-	-	-	N	N

Symbols: PA: flat position; PB: horizontal vertical position; PC: horizontal position; PD: horizontal overhead position; PE: overhead position; PF: vertical up position; PG: vertical down position; PH: pipe position for welding upwards; PJ: pipe position for welding downwards; Y: yes; P: possible; N: no; “-”: not applicable.

, the possibility of welding at particular welding positions with the use of the 3D-printed welding coupons is shown. The positions are indicated in accordance with [51]. Some of the welding positions can be achieved once a particular welding coupon is placed flat, e.g., on a working table, which is indicated with “Y”. Other placements of particular welding coupons, e.g., via mounting on a holder on a stand, make it possible to achieve some other positions, as indicated with “P”. The set of 3D-printed coupons does not cover joining a pipe to a plate; thus, some of the positions cannot be achieved, as indicated with “N” in the table. Combinations that do not exist are marked with “-”.

As was mentioned, in the VR scene, to visualize a 3D model of the plates or pipes and to simulate the creation of a weld, the dedicated VR controller is used as the reference, regardless of whether it is mounted on a 3D-printed customized welding coupon or not. Therefore, the placement of the VR controller in a way that causes that the location of objects to be welded in the VR scene imitates their location in the real working environment makes it possible to carry out a welding task without the use of a 3D-printed customized coupon (Figure 5).

The intangible part of the VR welding simulator includes the following components:

• A website that serves as the starting screen with access to welding tasks (Figure 6).
• A website that serves as the starting screen of the selected VR welding task (Figure 7).
• A VR scene in which the virtual welding is carried out. A view from the VR scene and the corresponding 3D-printed customized welding coupon are presented in Figure 8. It should be noted that the view through the VR goggles is in AR mode. Thus, it also includes the real environment (displayed in greyscale) in which the user carries out the welding task, which is not shown in Figure 8.

All the software items are uploaded on the server, and the number of users that can access and use the VR welding simulator at the same time is limited only by the server capabilities.

3.3. VR Welding Simulator Operation

In Figure 9, the operation of the VR welding simulator is presented, taking into account the actions of the user and processes in the system. The assumption is that all the components of the simulator, including the optional ones, are used.

After preparing the training stand (locating the customized welding coupon in the desired way), putting on the VR goggles, and holding the controller with the welding torch, the user goes to the website in which access to the welding tasks is provided. After selection of a task, the starting screen (Figure 7) of the task with information about the weld to be created and the values of the welding parameters to meet is shown. Additionally, the users can select whether they wish to display the VR scene in VR mode (fully immersive) or in AR mode (immersion in real environment displayed in greyscale), and they can turn on left-hand mode (right-hand mode is default).

By pressing one of the display mode buttons, the user is moved to the VR environment (Figure 10) in which they perform the welding operation.

In the scene, there are the following elements:

• An informative board (Figure 11) showing the required values of the welding parameters in the selected task and the overall correctness. The board is consistent with the one shown on the starting screen of the task. The later one is updated in line with the task realization. The board is located in front of the user in such a way that it does not disturb observation of the working area.

• A virtual welding torch. The 3D model follows movements of the assigned VR controller. If the 3D-printed customized welding torch is used, the 3D model perfectly covers it.
• A virtual welding coupon composed of elements to be welded and a weld path (marked in red). The location of the 3D model is established by the placement of the assigned VR controller. As in the case of the welding torch, if a 3D-printed customized welding coupon is used, the virtual element perfectly covers its 3D-printed counterpart. Along with the task realization, on the 3D model, the created weld is shown. It is marked in green if it is correct; otherwise, it is in red (Figure 12).

Figure 12. An example of a virtual welding coupon.

Figure 12. An example of a virtual welding coupon.

• An informative label attached to the virtual welding torch. The current values of the welding parameters are displayed on this label. The label remains oriented towards a trainee who can easily read the information. A green color indicates correct values and a red color indicates incorrectness.
• A reset box that enables the user to restart the creation of the weld.

The user positions the welding torch towards the welding coupon and leads the torch along the weld path. While moving the torch, a dedicated button on the controller has to be pressed to enable creation of the weld. The welding simulation is accompanied by sound effects resembling the real ones. The weld becomes visible only if the achieved values of the welding parameters enable this in the real welding environment. As mentioned above, the correctness of the weld is marked with green and incorrectness with red. During the welding, both on the informative board and on the informative label, the displayed data are being updated. When the task is completed, the summing-up assessment is visible on the informative board (“overall correctness” in Figure 11); this shows the percentage of green-marked weld measured against the whole weld.

The view of the VR environment that a trainee sees in their VR goggles can be displayed on a screen (e.g., a display TV, a computer screen) in real-time mode.

3.4. Development Process

3.4.1. General Description

The very first version of the VR welding simulator included one welding task—the creation of a fillet weld to join two plates. When the system’s expected functionality was achieved, other tasks were added.

The programming work was carried out with the use of the technologies HTML, JavaScript, WebXR, three.js, and A-Frame, and included the following:

• The development of the website for the starting screen of the VR welding simulator. This is a HTML website with links to the starting screens of welding tasks.
• The development of the website for the starting screen of a welding task. This is created with the use of HTML and JavaScript. The latter is used to define actions assigned to the button enabling the switch to left-handed mode and to the buttons that open the VR working environment (where the welding tasks are be carried out) in VR mode and AR mode, respectively.
• The development of the VR welding environment for carrying out the welding tasks.

3.4.2. Creation of the VR Welding Environment

The creation of the VR welding environment included the following activities:

1.

Creating the VR welding environment for one type of welding task. This involved the following steps:

• Developing a simulation presenting the creation of a fillet weld to join two plates (Figure 13). In the VR scene, after locating the VR torch close to the VR welding coupon, pointing it (namely the controller beam) towards the red-marked welding path, and pressing the dedicated button on the controller, drops indicating the formation of the weld were added. At this stage, only the VR set was used; no 3D-printed components were employed.

Figure 13. An example of the simulation of the weld creation.

Figure 13. An example of the simulation of the weld creation.

• Incorporating continuous measuring of the welding parameters, i.e., travel speed, travel angle, work angle, CWTD, checking their correctness against the limit values, and implementing measures to provide information on these to the user (as described earlier) via the informative board, the informative label, and the color of the created weld (namely, the color of drops that are created to form the virtual weld).
• Incorporating an option to switch between right-hand mode and left-hand mode.
• Incorporating the second controller as a reference for the placement of a virtual welding coupon in the VR scene. The intended situation is that the controller is mounted on the 3D-printed customized welding coupon; however, this is not mandatory.

2.

Adding other welding tasks.

The following tasks have been added to the VR welding simulator: two plates joined with a butt weld (in flat and in vertical positions), and two pipes joined with a butt weld. These are tasks that correspond to the 3D-printed customized welding coupons placed on a table. Relevant 3D models of welding coupons to be displayed in the VR scene had to be prepared and the data establishing the limit values of the welding parameters had to be defined.

JavaScript technology, including A-Frame, was used for the creation of the VR welding environment to be run in a web browser with WebXR support.

The placement of a 3D model of a welding coupon and 3D model of the welding torch in the VR scene, based on the location of the VR controllers (they are used as a reference), was established with use of A-Frame.

To allow a simulation of the weld creation, with the use of A-Frame, a weld path is added to the virtual welding coupon and the welding parameters are calculated while the user moves the virtual torch. The weld is made of very closely located spheres. The CWTD parameter is calculated with use of A-Frame, specifically the ‘raycaster’ component, which is responsible for the creation of the laser beam of the virtual welding torch. The distance between the end of the virtual welding torch and the point at which the beam intersects the weld path is directly retrieved; no additional calculation has to be conducted. JavaScript is employed for the calculation of the angle parameters based on vectors identified in the VR scene and relevant mathematical operations. The travel speed is identified based on distances between drops (spheres) forming the weld and the time necessary for their creation. With the use of JavaScript, the following operations are also defined: (1) a comparison of the obtained values of the parameters with the limit ones; (2) the formation of the virtual weld from spheres in the color reflecting the correctness of the welding operation; and (3) display of the updated values on the informative board and the informative label.

3.4.3. Development of 3D Models and 3D Printouts

For the VR welding simulator, the following 3D models were developed:

• 3D models to be used in the VR scene:
  • A 3D model of a welding torch (Figure 14a).
  • 3D models of welding coupons (Figure 14b); in the VR scene, a 3D model of a weld path (in a red color) is added to each 3D model of a welding coupon (Figure 12).

• 3D models of objects to be 3D-printed:
  • 3D models of elements of the customized welding torch (Figure 15a).
  • 3D models of the customized welding coupons (Figure 15b).

Figure 15. Three-dimensional models of the components to be 3D-printed: (a) parts of the customized welding torch; (b) an example of a customized welding coupon.

Figure 15. Three-dimensional models of the components to be 3D-printed: (a) parts of the customized welding torch; (b) an example of a customized welding coupon.

The 3D models of the customized components were developed based on the 3D geometrical models of their original counterparts, i.e., those developed for the VR scene. Thus, they cover each other perfectly while carrying out a welding task.

For all the 3D printouts, it was assumed that there were no particularly high requirements with regards to surface porosity and strength. The FDM (fused deposition modeling) method was used. The prepared 3D printouts of elements of the customized welding torch were glued together. The 3D printing was carried out on a Creality CR-10 S5 3D printer (Creality, Shenzhen, China) using a PLA filament. The following parameters were set for the process: a layer thickness of 0.2 mm, an infill density of 50%, and an infill pattern of the cubic subdivision.

4. Results

The ready-to-use VR welding simulator underwent tests by welding trainers. They had no previous experience with using welding simulators based on VR.

The full hardware version of the simulator, i.e., the VR set, the 3D-printed customized welding torch, and the 3D-printed customized welding coupons, was used.

The objective of the tests was to gather opinions regarding the perceived usability of the presented solution. Observations and interviews were carried out. The ultimate objective was to identify whether and in what way the VR welding simulator should be refined before testing by trainees.

The tests were organized with the intention to include the experience of both a trainee and a trainer in training with the VR welding simulator. To meet this objective, the following measures were taken:

• The tests took place in a room equipped with a display TV on which the view from the VR goggles was shown.
• The tests were carried out in two-person teams of welding trainers—one of them took on the role of a trainee who carried out the welding task with the use of the simulator and the other one took on the role of a trainer who observed the trainee during this training session; next, the test participants switched the roles.

The following tasks were carried out by each test participant:

• Joining two plates with a fillet weld in horizontal vertical position.
• Joining two plates with a butt weld in vertical position.
• Joining two pipes with a butt weld in horizontal position.

The actual testing was preceded by the delivery of introductory information about the VR welding simulator and a short set of instructions regarding the use of the system, covering its software and hardware components. The trainers invited to perform the tests were informed about the scenario and the objective of the tests. The idea of playing the role of a “trainer” and of a “trainee” was particularly explained. The test participants were also asked to immediately report any inconvenience or difficulties experienced while carrying out a welding task as a “trainee” or while observing the “trainee” carrying out a welding task as a “trainer”.

No problems with the use of the 3D-printed customized torch were observed. The test participants expressed their positive attitude to the proposed solution and shared remarks about improvements that should be introduced. They also expressed willingness to test the refined version of the VR simulator during the welders’ training at their facility.

The test participants confirmed the great potential of the VR welding simulator as a tool for training welders. In their opinion, it could contribute significantly to reducing the costs of training, especially in the case of novice welders. The trainers found the possibility to observe a trainee and to see the view from their VR goggles (e.g., shown on a screen or a computer monitor) at the same time very useful. In their opinion, they felt this could enable them to identify the trainees’ errors immediately and give relevant feedback and instructions to them. The assessment of a trainee’s performance provided in the simulator was found to be reliable and helpful. The possibility of using the 3D-printed customized welding coupons was perceived as contributing to the impression of welding on a real training stand.

The test participants raised the issue that achieving the required values of the parameters could be too challenging for beginner welders and proposed adding lighter tasks as an optional first step of training when using the VR welding simulator. It was also indicated that once the welded plates were placed vertically, the informative label in the current location was disturbing, as it obstructed the view of the welded objects. Improving the smoothness of the welding simulation was another recommendation.

Based on the feedback obtained, the following changes were introduced:

• Simulator performance was improved by reducing the detail of the geometric model of the weld.
• For the already available tasks, an easier version—with a lower level of difficulty—was added (Figure 16). The tolerance for the angles was increased (from 10° to 30°, i.e., evenly 15° in each direction). This resulted in two categories of tasks on the starting screen mentioned earlier, i.e., ‘easy exercises’ and ‘difficult exercises’.
• For the indicated welding task, the informative label was moved above the jointed elements (Figure 17).

5. Discussion

Comparing the proposed VR welding simulator to commercialized solutions that are mature in terms of technology and refined to meet users’ needs allows us to make some remarks with regards to its advantages, disadvantages, and recommended or possible development directions.

Generally, VR welding simulators are designed in such a way that the user neither can substitute any of the hardware components nor has to use their own hardware component or components. An example of an exception—identified within the study—is guideWELD^® VR, the implementation of which requires a user’s computer set (a computer unit and a monitor) that meets the defined system requirements. It seems that developers of VR welding simulators take into consideration that there is a demand for portable versions of their solutions; they offer product variants that can be assembled on and used at a table. It can also be observed that VR welding simulators are developed as a ‘complete training system’. They are not limited to delivering virtual welding tasks. They also include a database system in which the data regarding students, trainers, carried-out tasks (scores, recordings of the weld creation, etc.), and learning materials are stored.

In the proposed VR welding simulator, the software part is located on the server and is accessed via an Internet browser, and the minimum requirement with regards to hardware is a wireless VR set (VR goggles and VR controllers) that is available on the market at a reasonable price. This makes the solution highly portable and affordable.

The controllers are used as a reference to establish the location of the virtual welding coupon and the virtual welding torch in the VR scene in which the welding task is carried out. They can be mounted on the 3D-printed customized welding torch and the 3D-printed customized welding coupons that are optional hardware components of the VR welding simulator. The use of these 3D printouts contributes to the users’ feeling of carrying out the welding operation in real life. The VR controller assigned to the virtual welding torch in the 3D scene serves as the handle of the torch, and a switch on the VR controller serves as the trigger of the torch. This enables users to carry out welding tasks without having a welding torch (or its replica, e.g., a 3D-printed one), which might be seen as an advantage when comparing to other solutions, but at the same time, the following limitations of the VR welding simulator can be indicated:

• The user holds a VR controller instead of the handle of a welding torch or its replica; thus, the welding operation carried out in the VR environment only partly reflects the real one.
• The user cannot wear protective gloves.

These limitations were not raised by the welding trainers who tested the simulator. In the authors’ opinions, the main implication of these limitations is that the VR welding simulator should be used to support an initial training of novice welders. It enables users to learn what the welding parameters mean in practice and how a welding torch should be moved and oriented towards the welded elements to meet the required values of the welding parameters; however, it only partly enables them to acquire the skill of moving and orienting a real welding torch properly. Finding a solution to that problem might be a subject of further work on the VR welding simulator. In particular, the 3D-printed customized welding torch can be redesigned in a way that both enables users to hold it by the handle, in a similar way to a real welding torch, and enables them to mount a VR controller on it. To introduce such a modification in design, relevant changes will also have to be introduced in the software component of the VR welding simulator.

The presented VR welding simulator can be expanded in the following ways:

• The current version of the simulator does not cover the creation of a weld to join a pipe and a plate, but it is possible (1) to add a welding task that covers this, and (2) to make a necessary 3D-printed customized welding coupon.
• Functionalities of a ‘training system’ can be added, following the example of commercial VR welding simulators.

With regards to the latter, this paper’s authors think that it should be thoroughly thought over and suggest the delivery of two versions of the simulator—a basic one (the current one) and an expanded one. The simplicity of the current version of the VR welding simulator makes it a convenient and highly portable solution that does not require additional procedures and organizational activities (e.g., no system administrator has to be assigned) regarding the training process.

The developed solution combines features of VR-based and AR-based welding simulators. It can be used in VR mode or AR mode; thus, it can be used both by users prone to cybersickness and those who are not. In the VR mode, any working environment can be shown (uploaded to the VR scene). In the AR mode, the place in which the trainee is present while carrying out a welding task is observed, which is an alternative to full immersion in the VR environment. During the development and testing of the VR welding simulator, a VR set, Meta Oculus Quest 2, was used; thus, the view of the real environment around the trainee was provided in greyscale. The solution is compatible also with the VR set Meta Oculus Quest 3, in which the greyscale mode has been replaced with full-color mode. In the opinion of the authors of this paper, research to compare the meaning of such a difference in observation of the surrounding environment while carrying out a welding task with the use of a VR welding simulator might bring interesting findings.

The simulator enables training that meets the training principles indicated by Whitney and Stephens [5]:

• Trainees can practice skills that will contribute to their abilities to carry out real welding operations.
• The correctness of the welding operation is monitored.
• The students are continuously informed about how they perform and receive summing-up information when they complete the task.

The effectiveness of the developed VR welding simulator as a training aid has not yet been studied and should be a subject of further studies.

6. Conclusions

VR welding simulators enable a reduction in the costs and time spent on the practical training of welders. There is a wide range of such solutions on the market; however, their implementation can still be beyond the financial capabilities of many educational and training units. In this paper, a concept and a prototype of a VR welding simulator for training in MIG/MAG developed with the objective of creating a non-costly and easy-to-implement alternative to existing simulators is presented. During the development process, the solution underwent pilot tests in which welding trainers expressed their opinions based on which relevant modifications were introduced. It seems that the implementation of the final version of the VR welding simulator is within the capabilities of any education or training unit where welders are trained.

The proposed solution is portable and does not require hardware that is expensive, not possible to be purchased on one’s own, etc. The minimum hardware is an available-on-the-market wireless VR set with Internet access. The other physical components can be manufactured with FDM (fused deposition modeling), which is a common, affordable 3D printing method. Having the properly prepared STL files of these objects is sufficient to be able to physically make them. Thus, although the components are customized, they can be easily organized by a user. The capabilities of users with regards to the number of trainees trained at the same time are limited by the number of VR sets they have. Another factor might be the availability of trainers who accompany the trainees during the welding task.

It should be noted that an off-the-shelf wireless VR set is a tool that can be used in a variety of ways for training purposes and other reasons. Therefore, a user does not have to invest in ICT equipment that would be applied only to use the VR simulator.

What distinguishes the presented VR welding simulator is the way in which it combines VR and AR technologies. This is implemented by the possibility to select VR mode or AR mode before entering the VR environment, which makes it possible to differ the way the user is immersed in the working environment surrounding them. This makes it possible for the simulator to be used regardless of one’s cybersickness vulnerability.

The planned future work includes adding welding tasks; conducting tests of the VR welding simulator by trainees; holding interviews with trainers and trainees to establish if adding of training system functionalities is expected and, if yes, in what way; completing studies regarding an integration of the VR welding simulator in educational units and training companies where welders are taught.