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Actuators
Volume 12
Issue 3
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Actuators, Volume 12, Issue 3 (March 2023) – 43 articles

Cover Story (view full-size image): The rotary hybrid prosthesis rotates the knee joint using two approaches: one with the rotary cylinder body fixed and the blade within the rotary hydraulic cylinder rotating, and the other with the rotary blade fixed and the rotary hydraulic cylinder body itself rotating. The rotation of the motor drive module is locked in passive mode by the electrical brake of the motor drive module, which prevents the rotation of the rotary cylinder body connected to the timing belt. As a result, the rotation of the blade within the rotary cylinder is entirely responsible for knee flexion/extension. In active mode, the hydraulic nozzle fully closes, suppressing the rotation of the rotary blade. The electronic brake in the motor drive module is released, allowing the rotary hydraulic cylinder’s body to rotate using the motor power. View this paper
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24 pages, 1527 KiB  
Article
Implementation of a Cascade Fault Tolerant Control and Fault Diagnosis Design for a Modular Power Supply
by Abdelaziz Zaidi, Oscar Barambones and Nadia Zanzouri
Actuators 2023, 12(3), 135; https://doi.org/10.3390/act12030135 - 22 Mar 2023
Cited by 3 | Viewed by 2336
Abstract
The main objective of this research work was to develop reliable and intelligent power sources for the future. To achieve this objective, a modular stand-alone solar energy-based direct current (DC) power supply was designed and implemented. The converter topology used is a two-stage [...] Read more.
The main objective of this research work was to develop reliable and intelligent power sources for the future. To achieve this objective, a modular stand-alone solar energy-based direct current (DC) power supply was designed and implemented. The converter topology used is a two-stage interleaved boost converter, which is monitored in closed loop. The diagnosis method is based on analytic redundancy relations (ARRs) deduced from the bond graph (BG) model, which can be used to detect the failures of power switches, sensors, and discrete components such as the output capacitor. The proposed supervision scheme including a passive fault-tolerant cascade proportional integral sliding mode control (PI-SMC) for the two-stage boost converter connected to a solar panel is suitable for real applications. Most model-based diagnosis approaches for power converters typically deal with open circuit and short circuit faults, but the proposed method offers the advantage of detecting the failures of other vital components. Practical experiments on a newly designed and constructed prototype, along with simulations under PSIM software, confirm the efficiency of the control scheme and the successful recovery of a faulty stage by manual isolation. In future work, the automation of this reconfiguration task could be based on the successful simulation results of the diagnosis method. Full article
(This article belongs to the Special Issue Actuators in 2022)
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17 pages, 5509 KiB  
Article
The Residual Stress Relief and Deformation Control of Al Alloy Thin-Walled Antenna Components by Ultrasonic Regulation
by Wen-Yuan Song, Chun-Guang Xu, Qin-Xue Pan, Pei-Lu Li and Tao Yu
Actuators 2023, 12(3), 134; https://doi.org/10.3390/act12030134 - 22 Mar 2023
Cited by 1 | Viewed by 2357
Abstract
The residual stress fields of the initial billet and subsequent machining in the material bring great challenges to the precision machining and geometrical stability of aluminum alloy thin-walled components. To ensure that a certain type of large-sized aluminum alloy thin-walled antenna has a [...] Read more.
The residual stress fields of the initial billet and subsequent machining in the material bring great challenges to the precision machining and geometrical stability of aluminum alloy thin-walled components. To ensure that a certain type of large-sized aluminum alloy thin-walled antenna has a small flatness deformation during forming, this paper firstly employed the ultrasonic critical refraction longitudinal wave (LCR wave) detection method to measure the different depth ranges’ residual stress distribution of 5A06/6061/7075 aluminum alloy plate, both as blanks and after multiple milling. Additionally, the effects of inherent residual stress (IRS) and machining-induced residual stress (MIRS) on the subsequent milling deformation were analyzed. After that, combined with the self-developed ultrasonic stress relief (USR) system, the deformation control effect of a thin-walled plate after eliminating residual stress in each stage was tested. The results show that the ultrasonic stress relief treatment can quickly and efficiently eliminate the IRS and MIRS with small flatness deformation. By introducing the URS treatment in the blank, rough machining, and semi-finishing stages, the components before each subsequent machining are in a low-stress state, and the component deformation can be gradually controlled so that the final thin-walled antenna has a smaller flatness. Full article
(This article belongs to the Section Actuators for Manufacturing Systems)
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16 pages, 3087 KiB  
Article
Optimization of the Storage Spaces and the Storing Route of the Pharmaceutical Logistics Robot
by Ling Zhang, Shiqing Lu, Mulin Luo and Bin Dong
Actuators 2023, 12(3), 133; https://doi.org/10.3390/act12030133 - 21 Mar 2023
Viewed by 2173
Abstract
Auto drug distribution systems are used popularly to replace pharmacists when drugs are distributed in pharmacies. The Cartesian robot is usually used as the recovery mechanism. Under non-dynamic storage location conditions, generally, the selected planning route of the Cartesian robot is definite, which [...] Read more.
Auto drug distribution systems are used popularly to replace pharmacists when drugs are distributed in pharmacies. The Cartesian robot is usually used as the recovery mechanism. Under non-dynamic storage location conditions, generally, the selected planning route of the Cartesian robot is definite, which makes it difficult to optimize. In this paper, storage spaces were distributed for different drugs, and the route of storing was broken down into multiple path optimization problems for limited pick points. The path was chosen by an improved ant colony algorithm. Experiments showed that the algorithm can plan an effective storing route in the simulation and actual operation of the robot. The time spent on the route by improved ant colony algorithm sequence (IACS) was less than the time spent of route by random sequence (RS) and the time spent of route by traditional ant colony algorithm sequence (ACS); compared with RS, the optimized rate of restoring time with iacs can improve by 22.04% in simulation and 7.35% in operation. Compared with ACS, the optimized rate of restoring time with iacs was even more than 4.70% in simulation and 1.57% in operation. To the Cartesian robot, the optimization has certain guiding significance of the application on the 3D for improving quality. Full article
(This article belongs to the Special Issue Actuators in Robotic Control—2nd Edition)
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20 pages, 6356 KiB  
Article
A Compact Electromagnetic Dual Actuation Positioning System with a 10 mm Range and Nanometer Resolution
by Bimal Jeet Goteea, Qianjun Zhang and Wei Dong
Actuators 2023, 12(3), 132; https://doi.org/10.3390/act12030132 - 21 Mar 2023
Cited by 1 | Viewed by 2055
Abstract
In this manuscript, a compact electromagnetic dual actuation positioning system (CEDAPS) based on the Lorentz force principle that features a 10 mm range and nanometer-scale resolution with flexure guides is presented. Firstly, the stiffness of the flexure mechanism is modelled. Secondly, based on [...] Read more.
In this manuscript, a compact electromagnetic dual actuation positioning system (CEDAPS) based on the Lorentz force principle that features a 10 mm range and nanometer-scale resolution with flexure guides is presented. Firstly, the stiffness of the flexure mechanism is modelled. Secondly, based on it, the primary coil is designed, and from its performance, a suitable secondary coil is made to compensate for the deficiency of the primary actuation subsystem. The characteristics of the forces generated by these coils are also evaluated by an electromagnetic FEA simulation. Thirdly, a control scheme is presented that combines the performances of these two actuators, and finally, a prototype is fabricated to evaluate the performance. The results show a 10 nm resolution for a 10 mm (±5 mm) stroke with low sub-micron sinusoidal tracking errors and nanometer accuracy for step tracking under the proposed control scheme. The thermal properties of the system are also presented. Full article
(This article belongs to the Special Issue Advanced Actuation, Intelligent Sensor and Precise Manipulation Technology in Human–Robot Interaction)
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11 pages, 4117 KiB  
Article
Implementation of Smart Materials for Actuation of Traditional Valve Technology for Hybrid Energy Systems
by Saqlain Zaman, Alba Leyva, Md Sahid Hassan, Ariztbe Valladolid, Nicolas E. Herrera, Sofia Gabriela Gomez, Md Shahjahan Mahmud, David Tucker, Comas Haynes and Yirong Lin
Actuators 2023, 12(3), 131; https://doi.org/10.3390/act12030131 - 20 Mar 2023
Cited by 4 | Viewed by 2298
Abstract
The ever-changing nature of the power industry will require the implementation of hybrid energy systems. Integration of tightly coupled components in hybrids often involves the diversion of exhaust gas flow. An innovative smart material actuation technology is proposed to replace traditional electro-mechanical actuated [...] Read more.
The ever-changing nature of the power industry will require the implementation of hybrid energy systems. Integration of tightly coupled components in hybrids often involves the diversion of exhaust gas flow. An innovative smart material actuation technology is proposed to replace traditional electro-mechanical actuated valve mechanisms with lighter and less expensive actuators. A shape memory alloy (SMA) spring-actuated valve was designed for high-temperature service to demonstrate the promise of smart materials in control valve applications. With SMA springs only generating a maximum force of 3.2 N, an innovative valve design was necessary. To demonstrate the concept, a 3-inch Nominal Pipe Size valve was designed, and 3D printed using the stereolithography technique. Increasing the electrical current to actuate the SMA springs reduced actuation time. The maximum current of 10 A produced the lowest actuation time of 2.85 s, with an observed maximum stroke rate of more than 100 stroke completion %/s (considering actuation open/close as 100% stroke) at the midrange. The final assembly of the valve was estimated to provide a cost reduction of more than 30% and a weight reduction of more than 80% compared to the other available automatic valves in the present market. Full article
(This article belongs to the Section Actuator Materials)
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17 pages, 576 KiB  
Article
Fixed-Time Adaptive Tracking Control for a Quadrotor Unmanned Aerial Vehicle with Input Saturation
by Haihui Wang, Guozeng Cui and Huayi Li
Actuators 2023, 12(3), 130; https://doi.org/10.3390/act12030130 - 18 Mar 2023
Cited by 3 | Viewed by 1750
Abstract
Considering the problem of tracking control for a quadrotor unmanned aerial vehicle (QUAV) with input saturation, parameter uncertainties and external disturbances, a command filtered backstepping-based fixed-time adaptive control scheme was developed. The problem of “explosion of complexity” (EOC) is tackled by utilizing the [...] Read more.
Considering the problem of tracking control for a quadrotor unmanned aerial vehicle (QUAV) with input saturation, parameter uncertainties and external disturbances, a command filtered backstepping-based fixed-time adaptive control scheme was developed. The problem of “explosion of complexity” (EOC) is tackled by utilizing the fixed-time command filter, and the influence of filtered error is removed based on the fractional power-error-compensation mechanism. A fixed-time auxiliary system was designed to compensate for the input saturation of the QUAV. It strictly proves that the closed-loop system signals are fixed-time bounded, and the tracking errors converge to a sufficiently small region near the origin in a fixed time, and the convergence time is independent of the initial states. Finally, the effectiveness of the proposed fixed-time adaptive control algorithm is demonstrated via a numerical simulation. Full article
(This article belongs to the Section Control Systems)
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13 pages, 3720 KiB  
Article
Effect of Material Properties on Fiber-Shaped Pneumatic Actuators Performance
by Muh Amdadul Hoque, Emily Petersen and Xiaomeng Fang
Actuators 2023, 12(3), 129; https://doi.org/10.3390/act12030129 - 18 Mar 2023
Cited by 4 | Viewed by 16837
Abstract
Thin fiber-shaped pneumatic artificial muscle (PAM) can generate contractile motions upon stimulation, and it is well known for its good compliance, high weight-to-power ratio, resemblance to animal muscle movements, and, most importantly, the capability to be integrated into fabrics and other textile forms [...] Read more.
Thin fiber-shaped pneumatic artificial muscle (PAM) can generate contractile motions upon stimulation, and it is well known for its good compliance, high weight-to-power ratio, resemblance to animal muscle movements, and, most importantly, the capability to be integrated into fabrics and other textile forms for wearable devices. This fiber-shaped device, based on McKibben technology, consists of an elastomeric bladder that is wrapped around by a braided sleeve, which transfers radial expansion into longitudinal contraction due to the change in the sleeve’s braiding angle while being inflated. This paper investigates the effect of material properties on fiber-shaped PAM’s behavior, including the braiding yarn and bladder’s dimensional and mechanical properties. A range of samples with combinations of yarn and bladder parameters were developed and characterized. A robust fabrication process verified through several calibration and control experiments of PAM was applied, which ensured a more accurate characterization of the actuators. The results demonstrate that material properties, such as yarn stiffness, yarn diameter, bladder diameter, and bladder hardness, have significant effects on PAMs’ deformation strains and forces generated. The findings can serve as fundamental guidelines for the future design and development of fiber-shaped pneumatic actuators. Full article
(This article belongs to the Special Issue Wearable E-Textile Technologies: Sensors, Actuators, and Integrated Systems)
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18 pages, 6156 KiB  
Article
A Practical Deceleration Control Method, Prototype Implementation and Test Verification for Rail Vehicles
by Tianhe Ma, Chun Tian, Mengling Wu, Jiajun Zhou and Yinhu Liu
Actuators 2023, 12(3), 128; https://doi.org/10.3390/act12030128 - 17 Mar 2023
Cited by 1 | Viewed by 2337
Abstract
Currently, the theoretical braking force control mode, characterized by actual deceleration as an unstable open-loop output, is the most widely used brake control mode in trains. To overcome the shortcomings of non-deceleration control modes, a deceleration control mode is proposed to realize the [...] Read more.
Currently, the theoretical braking force control mode, characterized by actual deceleration as an unstable open-loop output, is the most widely used brake control mode in trains. To overcome the shortcomings of non-deceleration control modes, a deceleration control mode is proposed to realize the closed-loop control of train deceleration. First, a deceleration control algorithm based on parameter estimation was derived. Then, the deceleration control software logic was designed based on the existing braking system to meet the engineering requirements. Finally, the deceleration control algorithm was verified through a ground combination test bench with real brake control equipment and pneumatic brakes. The test results show that the deceleration control can make the actual braking deceleration of the train accurately track the target deceleration in the presence of disturbances, such as uncertain brake pad friction coefficients, line ramps, vehicle loads and braking force feedback errors, as well as their combined effects, and does not affect the original performance of the braking system. The average deceleration in the deceleration control mode is relatively stable, and the control error of instantaneous deceleration is smaller. Full article
(This article belongs to the Special Issue Actuators and Control of Intelligent Electric Vehicles)
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25 pages, 16769 KiB  
Article
Distributed Model Predictive Control with Particle Swarm Optimizer for Collision-Free Trajectory Tracking of MWMR Formation
by Tian Zhang and Xiangyin Zhang
Actuators 2023, 12(3), 127; https://doi.org/10.3390/act12030127 - 16 Mar 2023
Cited by 5 | Viewed by 2189
Abstract
The distributed model predictive control (DMPC) strategy with particle swarm optimization (PSO) is applied to solve the collision-free trajectory tracking problem for the mecanum-wheeled mobile robot (MWMR) formation. Under the leader–follower framework, the predictive model is established considering the kinematics and dynamics of [...] Read more.
The distributed model predictive control (DMPC) strategy with particle swarm optimization (PSO) is applied to solve the collision-free trajectory tracking problem for the mecanum-wheeled mobile robot (MWMR) formation. Under the leader–follower framework, the predictive model is established considering the kinematics and dynamics of the MWMR with the uncertainties and external disturbances. Based on the information from itself and its neighbors, each MWMR is assigned its own finite-horizon optimal control problem, of which the objective/cost function consists of formation maintenance, trajectory tracking, and collision avoidance terms, and the control inputs of each MWMR are computed synchronously in a distributed manner. PSO serves as the fast and effective optimizer to find feasible solutions to these finite-horizon optimal control problems. Further, the feedback emendation is implemented using a double closed-loop compensator to efficiently inhibit the influence of unknown dynamics in real time. The stability of the proposed distributed formation control approach is strictly analyzed. Numerical simulations confirmed the robustness and effectiveness of the control approach in obstacle environments. Full article
(This article belongs to the Section Control Systems)
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21 pages, 2146 KiB  
Article
Forced Servoing of a Series Elastic Actuator Based on Link-Side Acceleration Measurement
by Zhuo Wang, Shenghong Liu, Bo Huang, Haowu Luo and Feiyan Min
Actuators 2023, 12(3), 126; https://doi.org/10.3390/act12030126 - 15 Mar 2023
Cited by 1 | Viewed by 2208
Abstract
Joint stiffness of an elastic-joint robot can be changed according to joint stiffness requirements. A series elastic actuator (SEA) can reduce the contact stiffness between the body and the environment or human, which can further ensure interactive operation in a human–machine-compatible environment. However, [...] Read more.
Joint stiffness of an elastic-joint robot can be changed according to joint stiffness requirements. A series elastic actuator (SEA) can reduce the contact stiffness between the body and the environment or human, which can further ensure interactive operation in a human–machine-compatible environment. However, the introduction of the SEA improves the complexity of the robot dynamics model. In this paper, we propose a control schema based on link-side acceleration measurement to eliminate the overshoot and vibration in the transient process of force control. An extended Kalman filter (EKF) algorithm that fuses photoelectric encoders and accelerometers is first presented based on the link-side acceleration measurement. Following this, based on the external torque estimation, the vibration reduction control algorithm is designed. The simulation model is built, and the algorithm design and simulation of position control and force control are carried out and finally tested on the real robot platform. The effectiveness of the control algorithm is proved. The experimental results show that the dynamic response of the external force estimation is about 2 ms faster than that of the force sensor, and the error between the estimated external torque and the real external torque is within ±0.16 N·m. Full article
(This article belongs to the Special Issue Intelligent Control of Flexible Manipulator Systems and Robotics)
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14 pages, 8907 KiB  
Communication
Fault Detection and Localisation of a Three-Phase Inverter with Permanent Magnet Synchronous Motor Load Using a Convolutional Neural Network
by Dominik Łuczak, Stefan Brock and Krzysztof Siembab
Actuators 2023, 12(3), 125; https://doi.org/10.3390/act12030125 - 15 Mar 2023
Cited by 10 | Viewed by 2785
Abstract
Fault-tolerant control of a three-phase inverter can be achieved by performing a hardware reconfiguration of the six-switch and three-phase (6S3P) topology to the four-switch and three-phase (4S3P) topology after detection and localisation of the faulty phase. Together with hardware reconfiguration, the SVPWM algorithm [...] Read more.
Fault-tolerant control of a three-phase inverter can be achieved by performing a hardware reconfiguration of the six-switch and three-phase (6S3P) topology to the four-switch and three-phase (4S3P) topology after detection and localisation of the faulty phase. Together with hardware reconfiguration, the SVPWM algorithm must be appropriately modified to handle the new 4S3P topology. The presented study focuses on diagnosing three-phase faults in two steps: fault detection and localisation. Fault detection is needed to recognise the healthy or unhealthy state of the inverter. The binary state recognition problem can be solved by preparing a feature vector that is calculated from phase currents (ia, ib, and ic) in the time and frequency domains. After the fault diagnosis system recognises the unhealthy state, it investigates the signals to localise which phase of the inverter is faulty. The multiclass classification was solved by a transformation of the three-phase currents into a single RGB image and by training a convolutional neural network. The proposed methodology for the diagnosis of three-phase inverters was tested based on a simulation model representing a laboratory test bench. After the learning process, fault detection was possible based on a 128-sample window (corresponding to a time of 0.64 ms) with an accuracy of 99 percent. In the next step, the localisation of selected individual faults was performed on the basis of a 256-sample window (corresponding to a time of 1.28 ms) with an accuracy of 100 percent. Full article
(This article belongs to the Special Issue 10th Anniversary of Actuators)
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10 pages, 2437 KiB  
Article
Maskless Writing of Surface-Attached Micro-Magnets by Two-Photon Crosslinking
by Nicolas Geid, Jan Ulrich Leutner, Oswald Prucker and Jürgen Rühe
Actuators 2023, 12(3), 124; https://doi.org/10.3390/act12030124 - 15 Mar 2023
Cited by 4 | Viewed by 2109
Abstract
Surface-bound 3D micro-magnets are fabricated from photoreactive copolymers filled with magnetic nanoparticles by maskless 3D writing. The structures are generated by 2-photon crosslinking (2PC), which allows direct writing into solid films of composites consisting of magnetic particles and a photoreactive elastomer precursor. With [...] Read more.
Surface-bound 3D micro-magnets are fabricated from photoreactive copolymers filled with magnetic nanoparticles by maskless 3D writing. The structures are generated by 2-photon crosslinking (2PC), which allows direct writing into solid films of composites consisting of magnetic particles and a photoreactive elastomer precursor. With this strategy, it is possible to directly write complex, surface-bound magnetic actuator structures, which generates new opportunities in the fields of microfluidics and bioanalytical systems. Compared to the common 2-photon polymerization, in which the writing process takes place in a liquid resin, the direct writing based on the 2PC method takes place in a solid polymer film (i.e., in the glassy state). Full article
(This article belongs to the Special Issue Cooperative Microactuator Devices and Systems)
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23 pages, 4950 KiB  
Article
Adaptive Starting Control Strategy for Hybrid Electric Vehicles Equipped with a Wet Dual-Clutch Transmission
by Jun Guo and Yunqing Zhang
Actuators 2023, 12(3), 123; https://doi.org/10.3390/act12030123 - 14 Mar 2023
Cited by 9 | Viewed by 2574
Abstract
To improve the starting performance of the P2.5 plug-in hybrid electric vehicles with a wet dual-clutch transmission, an adaptive starting control strategy is presented in this paper, which controls the two clutches simultaneously involved in the starting process. A fuzzy controller is designed [...] Read more.
To improve the starting performance of the P2.5 plug-in hybrid electric vehicles with a wet dual-clutch transmission, an adaptive starting control strategy is presented in this paper, which controls the two clutches simultaneously involved in the starting process. A fuzzy controller is designed to identify the starting intention and determine the target torque under different working conditions. The starting process is divided into five periods, and linear quadratic optimal control is adopted to obtain the reference torque trajectory for the third period, while the others are determined by adaptive control by changing the adjustment coefficients according to the starting conditions. The combined pressure feedback controller based on the PID algorithm is proposed to control the wet clutch torque to follow the reference torque trajectory. The MATLAB/Simulink software platform is used to simulate the control strategy. The results show that the proposed strategy can shorten the starting time and reduce the level of jerk. Moreover, with the first-gear starting, the friction work of the whole process and clutch C1 is, respectively, reduced by 1.68% and 4.62% for slowly starting and 23.37% and 23.6% for quickly starting, which can significantly prolong the service lifetime of the clutch compared with the traditional single-clutch starting strategy. Full article
(This article belongs to the Special Issue Design, Control, and Optimization of Powertrain for New Energy Vehicles)
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25 pages, 4464 KiB  
Tutorial
Active Damping, Vibration Isolation, and Shape Control of Space Structures: A Tutorial
by André Preumont
Actuators 2023, 12(3), 122; https://doi.org/10.3390/act12030122 - 14 Mar 2023
Cited by 11 | Viewed by 3036
Abstract
This tutorial reviews the author’s contributions to the active control of precision space structures over the past 35 years. It is based on the Santini lecture presented at the IAC-2022 Astronautical Congress in Paris in September 2022. The first part is devoted to [...] Read more.
This tutorial reviews the author’s contributions to the active control of precision space structures over the past 35 years. It is based on the Santini lecture presented at the IAC-2022 Astronautical Congress in Paris in September 2022. The first part is devoted to the active damping of space trusses with an emphasis on robustness. Guaranteed stability is achieved by using decentralized collocated actuator–sensor pairs. The so-called integral force feedback (IFF) is simple, robust, and effective, and the performances can be predicted easily with simple formulae based on modal analyses. These predictions have been confirmed by numerous experiments. The damping strategy for trusses has been extended to cable structures, and also confirmed experimentally. The second part addresses the problem of vibration isolation: isolating a sensitive payload from the vibration induced by the spacecraft (i.e., the unbalanced mass of attitude control reaction wheels and gyros). A six-axis isolator based on a Gough–Stewart platform is discussed; once again, the approach emphasizes robustness. Two different solutions are presented: The first one (active isolation) uses a decentralized controller with collocated pairs of the actuator and force sensor, with IFF control. It is demonstrated that this special implementation of the skyhook, unlike the classical one, has guaranteed stability, even if the two substructures it connects are flexible (typical of large space structures). A second approach (passive) discusses an electromagnetic implementation of the relaxation isolator where the classical dash-pot of the linear damper is substituted by a Maxwell unit, leading to an asymptotic decay rate of −40 dB/decade, similar to the skyhook (although much simpler in terms of electronics). The third part of the lecture summarizes more recent work done on the control of flexible mirrors: (i) flat mirrors for adaptive optics (AO) controlled by an array of piezoelectric ceramic (PZT) actuators and (ii) spherical thin shell polymer reflectors controlled by an array of piezoelectric polymer actuators (PVDF-TrFE) aimed at being deployed in space. Full article
(This article belongs to the Special Issue Actuator Design and Control Strategy Development for Vibration Control in Precision Engineering)
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23 pages, 6591 KiB  
Article
Mechanism Analysis and Control of Lateral Instability of 4WID Vehicle Based on Phase Plane Analysis Considering Front Wheel Angle
by Haoran Tang, Shaoyi Bei, Bo Li, Xiaoqiang Sun, Chen Huang, Jing Tian and Hongzhen Hu
Actuators 2023, 12(3), 121; https://doi.org/10.3390/act12030121 - 13 Mar 2023
Cited by 3 | Viewed by 2319
Abstract
The current vehicle stability judgment methods in the stability control of distributed drive electric vehicles focuses on using the phase plane method, but the existing phase plane stability boundary delineation methods ignore the influence of the front wheel rotation angle. Therefore, a new [...] Read more.
The current vehicle stability judgment methods in the stability control of distributed drive electric vehicles focuses on using the phase plane method, but the existing phase plane stability boundary delineation methods ignore the influence of the front wheel rotation angle. Therefore, a new phase plane partitioning method (NPPPM) is proposed in this paper, and a new phase plane stability domain library is established. Based on this, the direct yaw moment control of distributed drive electric vehicle through phase plane analysis is established. Firstly, the influence of the front wheel turning angle on the phase plane is considered in the design of the phase plane stability boundary, and a new stability boundary function is fitted by the least squares method. This approach avoids the lateral instability caused by too large a front-wheel turning angle and improves the accuracy of vehicle stability judgment. Next, a hierarchical direct transverse moment controller is constructed using Matlab/Simulink. Among them, the upper layer controller adopts sliding mode control with the sideslip angle error of the center of mass as the tracking target. The lower controller adopts the optimal configuration algorithm with the optimal road adhesion utilization as the objective function. Finally, the effectiveness and superiority of the proposed phase plane partitioning method (NPPPM) for distributed drive electric vehicles with sinusoidal and angular order inputs for the front wheel rotation angle are verified by simulation. Full article
(This article belongs to the Section Actuators for Land Transport)
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14 pages, 19211 KiB  
Article
Design, Analysis, and Optimization of a Kinematically Redundant Parallel Robot
by Xu Liang, Xiang Zeng, Guotao Li, Wentao Chen, Tingting Su and Guangping He
Actuators 2023, 12(3), 120; https://doi.org/10.3390/act12030120 - 13 Mar 2023
Cited by 3 | Viewed by 3094
Abstract
It has been nearly 60 years since the introduction of the Gough–Stewart manipulator (GSM). With the advantages of superior load capacity and high precision, the GSM still plays an important role in many fields. However, the GSM has limitations such as a small [...] Read more.
It has been nearly 60 years since the introduction of the Gough–Stewart manipulator (GSM). With the advantages of superior load capacity and high precision, the GSM still plays an important role in many fields. However, the GSM has limitations such as a small workspace and complex singularities. To overcome these problems, a novel kinematically redundant parallel robot is designed with three redundant actuators added on the basis of the GSM. First, the structure of the proposed robot is introduced, and the kinematics of the proposed robot is established. Second, the workspaces of the proposed robot are analyzed, and the results show that the position workspace volume and the maximum torsion and orientation angles of the proposed robot can be improved effectively. Third, the singularities of the proposed robot and the GSM are compared based on the Jacobian matrices. Finally, the multi-parameter, multi-objective optimization is used to optimize the geometric parameters of the proposed robot, and an experimental prototype of the proposed robot is designed based on the optimization results. Full article
(This article belongs to the Section Actuators for Robotics)
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20 pages, 4796 KiB  
Article
Robust Liquid Level Control of Quadruple Tank System: A Nonlinear Model-Free Approach
by Zahraa Sabah Hashim, Halah I. Khani, Ahmad Taher Azar, Zafar Iqbal Khan, Drai Ahmed Smait, Abdulkareem Abdulwahab, Ali Mahdi Zalzala, Anwar Ja’afar Mohamad Jawad, Saim Ahmed, Ibraheem Kasim Ibraheem, Aws Abdulsalam Najm, Suliman Mohamed Fati, Mohamed Tounsi and Ahmed Redha Mahlous
Actuators 2023, 12(3), 119; https://doi.org/10.3390/act12030119 - 11 Mar 2023
Cited by 6 | Viewed by 2920
Abstract
In this paper, two new versions of modified active disturbance rejection control (MADRC) are proposed to stabilize a nonlinear quadruple tank system and control the water levels of the lower two tanks in the presence of exogenous disturbances, parameter uncertainties, and parallel varying [...] Read more.
In this paper, two new versions of modified active disturbance rejection control (MADRC) are proposed to stabilize a nonlinear quadruple tank system and control the water levels of the lower two tanks in the presence of exogenous disturbances, parameter uncertainties, and parallel varying input set-points. The first proposed scheme is configured from the combination of a modified tracking differentiator (TD), modified super twisting sliding mode (STC-SM), and modified nonlinear extended state observer (NLESO), while the second proposed scheme is obtained by aggregating another modified TD, a modified nonlinear state error feedback (MNLSEF), and a fal-function-based ESO. The MADRC schemes with a nonlinear quadruple tank system are investigated by running simulations in the MATLAB/SIMULINK environment and several comparison experiments are conducted to validate the effectiveness of the proposed control schemes. Furthermore, the genetic algorithm (GA) is used as a tuning algorithm to parametrize the proposed MADRC schemes with the integral time absolute error (ITAE), integral square of the control signal (ISU), and integral absolute of the control signal (IAU) as an output performance index (OPI). Finally, the simulation results show the robustness of the proposed schemes with a noticeable reduction in the OPI. Full article
(This article belongs to the Special Issue New Control Schemes for Actuators)
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18 pages, 4904 KiB  
Article
Selective Passive/Active Switchable Knee Prosthesis Based on Multifunctional Rotary Hydraulic Cylinder for Transfemoral Amputees
by Hyunjun Shin, Jinkuk Park, Huitae Lee, Sungyoon Jung, Mankee Jeon and Sehoon Park
Actuators 2023, 12(3), 118; https://doi.org/10.3390/act12030118 - 9 Mar 2023
Cited by 1 | Viewed by 2329
Abstract
Significant advances have been made in prostheses with the aim of enhancing the quality of life for transfemoral amputees. While commercially available transfemoral prostheses mainly focus on the developing passive prostheses that act only as dampers, academic research is centered round powered prostheses [...] Read more.
Significant advances have been made in prostheses with the aim of enhancing the quality of life for transfemoral amputees. While commercially available transfemoral prostheses mainly focus on the developing passive prostheses that act only as dampers, academic research is centered round powered prostheses that can provide net-positive knee torque. Although recent active-powered prostheses have made excellent progress in terms of weight and battery life, it remains unclear if these prostheses can be effectively used in everyday life. This study presents a rotary hybrid prosthesis based on the combination of a multifunctional rotary hydraulic cylinder that is designed to operate as a brake, clutch, and damper with a 100 W active motor system. This prosthesis enables long-term level ground walking while supplying active power as needed. The passive and active components of this hybrid prosthesis are designed such that they can be decoupled when operated independently, allowing for quick switching between passive and active modes in 50–100 ms. The study outlines the aims and procedures for the design of rotary hybrid prostheses, as well as the feasibility tests for each module and the amputee’s clinical test on the developed knee prosthesis. Full article
(This article belongs to the Section Actuators for Medical Instruments)
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22 pages, 8800 KiB  
Article
Intelligent Fault Prognosis Method Based on Stacked Autoencoder and Continuous Deep Belief Network
by Chao Zhang, Yibin Zhang, Qixuan Huang and Yong Zhou
Actuators 2023, 12(3), 117; https://doi.org/10.3390/act12030117 - 9 Mar 2023
Cited by 6 | Viewed by 1797
Abstract
Mechanical fault prediction is one of the main problems in condition-based maintenance, and its purpose is to predict the future working status of the machine based on the collected status information of the machine. However, on one hand, the model health indices based [...] Read more.
Mechanical fault prediction is one of the main problems in condition-based maintenance, and its purpose is to predict the future working status of the machine based on the collected status information of the machine. However, on one hand, the model health indices based on the information collected by the sensors will directly affect the evaluation results of the system. On the other hand, because the model health index is a continuous time series, the effect of feature learning on continuous data also affects the results of fault prognosis. This paper makes full use of the autonomous information fusion capability of the stacked autoencoder and the strong feature learning capability of continuous deep belief networks for continuous data, and proposes a novel fault prognosis method. Firstly, a stacked autoencoder is used to construct the model health index through the feature learning and information fusion of the vibration signals collected by the sensors. To solve the local fluctuations in the health indices, the exponentially weighted moving average method is used to smooth the index data to reduce the impact of noise. Then, a continuous deep belief network is used to perform feature learning on the constructed health index to predict future performance changes in the model. Finally, a fault prognosis experiment based on bearing data was performed. The experimental results show that the method combines the advantages of stacked autoencoders and continuous deep belief networks, and has a lower prediction error than traditional intelligent fault prognosis methods. Full article
(This article belongs to the Special Issue Electro-Mechanical Actuator, Diagnostic and Fault-Tolerant Control Systems)
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11 pages, 789 KiB  
Article
Design of High Precision Interval Observer for Robot System
by Shuang Duan, Zhida Shao, Xinyao Chen, Xuan Li, Yiyang Chen and Haidong He
Actuators 2023, 12(3), 116; https://doi.org/10.3390/act12030116 - 9 Mar 2023
Cited by 1 | Viewed by 1836
Abstract
In order to solve the problem of parameter uncertainty and unknown external interference of wheeled mobile robots (WMR) in a complex environment, the design of a high-precision interval observer for the robot system is proposed. In this paper, the kinematics and dynamics model [...] Read more.
In order to solve the problem of parameter uncertainty and unknown external interference of wheeled mobile robots (WMR) in a complex environment, the design of a high-precision interval observer for the robot system is proposed. In this paper, the kinematics and dynamics model of a wheeled mobile robot is derived first, and then the control strategy of high-precision interval observer is introduced to estimate and compensate for the unknown state and uncertainty of the system in real-time, which realizes the robustness of the system to disturbance and high adaptability to the environment. The stability of the system is proved by Lyapunov’s theory. The experimental results show that other methods based on coordinate transformation, though the design conditions are relaxed to a certain extent, bring some conservatism. The method proposed in this paper can obtain more accurate interval estimation, so the performance of the method proposed in this paper is better. In conclusion, the control method proposed in this paper can make the mobile robot system have good tracking control performance and strong robustness. Full article
(This article belongs to the Special Issue Advanced Actuation, Intelligent Sensor and Precise Manipulation Technology in Human–Robot Interaction)
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30 pages, 10791 KiB  
Review
Dielectric Elastomer Sensors with Advanced Designs and Their Applications
by Holger Böse and Johannes Ehrlich
Actuators 2023, 12(3), 115; https://doi.org/10.3390/act12030115 - 8 Mar 2023
Cited by 7 | Viewed by 3747
Abstract
Dielectric elastomer sensors (DESs) have been known as highly stretchable strain sensors for about two decades. They are composite films consisting of alternating dielectric and electrode layers. Their electrical capacitance between the electrodes is enhanced upon stretching. In this paper, a variety of [...] Read more.
Dielectric elastomer sensors (DESs) have been known as highly stretchable strain sensors for about two decades. They are composite films consisting of alternating dielectric and electrode layers. Their electrical capacitance between the electrodes is enhanced upon stretching. In this paper, a variety of advanced designs of DESs is introduced. An explanation of how these sensors work and how they perform in terms of capacitance versus deformation or load force is provided. Moreover, the paper describes how the sensor design affects the sensor characteristics in order to achieve a high measuring sensitivity. The most relevant quantities to be measured are distance variations or elongations, forces and pressure loads. It is demonstrated that the sensor design can be supported by Finite Element Method (FEM) simulations. In the second part of the paper, possible applications of the advanced DESs are outlined. Pure sensor applications to detect or monitor pressure or deformation are distinguished from other applications, where sensors form a part of a human–machine interface (HMI). DESs are predestined to be used in contact with the human body due to their softness and flexibility. In the case of an HMI, a dosed load on a sensor by the user’s hand enables the remote control of arbitrary technical functions. This can preferably be realized with an operating glove, which exhibits different categories of DESs. Possible applications of DESs are described with the support of functional demonstrators. Full article
(This article belongs to the Special Issue Smart Dielectric Elastomer Actuator and Sensor Systems)
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34 pages, 14498 KiB  
Review
Flexoelectric Effect of Ferroelectric Materials and Its Applications
by Dongxia Tian, Dae-Yong Jeong, Zhenxiao Fu and Baojin Chu
Actuators 2023, 12(3), 114; https://doi.org/10.3390/act12030114 - 7 Mar 2023
Cited by 12 | Viewed by 4111
Abstract
The flexoelectric effect, which exists in all dielectrics, is an electromechanical effect that arises due to the coupling of strain gradients (or electric field gradients) with electric polarization (or mechanical stress). Numerous experimental studies have demonstrated that ferroelectric materials possess a larger flexoelectric [...] Read more.
The flexoelectric effect, which exists in all dielectrics, is an electromechanical effect that arises due to the coupling of strain gradients (or electric field gradients) with electric polarization (or mechanical stress). Numerous experimental studies have demonstrated that ferroelectric materials possess a larger flexoelectric coefficient than other dielectric materials; thus, the flexoelectric response becomes significant. In this review, we will first summarize the measurement methods and magnitudes of the flexoelectric coefficients of ferroelectric materials. Theoretical studies of the flexoelectric coefficients of ferroelectric materials will be addressed in this review. The scaling effect, where the flexoelectric effect dramatically increases when reducing the material dimension, will also be discussed. Because of their large electromechanical response and scaling effect, ferroelectric materials offer vast potential for the application of the flexoelectric effect in various physical phenomena, including sensors, actuators, and transducers. Finally, this review will briefly discuss some perspectives on the flexoelectric effect and address some pressing questions that need to be considered to further develop this phenomenon. Full article
(This article belongs to the Special Issue Piezoelectric Actuators—A Special Issue in Honor of Prof. Dr. Kenji Uchino)
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34 pages, 8999 KiB  
Review
A Review on Vibration Control Strategies Using Magnetorheological Materials Actuators: Application Perspective
by Aji Masa’id, Bhre Wangsa Lenggana, U. Ubaidillah, Didik Djoko Susilo and Seung-Bok Choi
Actuators 2023, 12(3), 113; https://doi.org/10.3390/act12030113 - 3 Mar 2023
Cited by 15 | Viewed by 4019
Abstract
Magnetorheological (MR) materials are a group of smart materials used in new technologies with controlled reliability. The development of these materials is expanding, starting from MR fluids, elastomers, grease, and gel. This large number of material types further expands the various applications of [...] Read more.
Magnetorheological (MR) materials are a group of smart materials used in new technologies with controlled reliability. The development of these materials is expanding, starting from MR fluids, elastomers, grease, and gel. This large number of material types further expands the various applications of MR materials as a creative technology to support performance enhancement. For example, MR fluid is used to improve the performance of shock absorbers such as vehicle suspension, the damping of building structures, and polishing of the workpiece. MR elastomers are used for engine mounting, insulation base, and many other applications with intelligent material properties such as stiffness controllability. However, there are still complexities in the practical implementation of the control system beyond reliability. Many previous studies have focused on the performance improvement and reliability of MR materials as smart materials for application devices and systems. In this review article, the specific discussion related to vibration control strategies in MR material-based systems was thoroughly investigated. To discuss this point, many MR applications including transportation system and vibration isolation were adopted using different types of control strategies. Many different control strategies that have been used for MR applications such as fuzzy logic control, optimal control, and skyhook control are discussed in-depth in terms of the inherent control characteristics of merits and demerits. Full article
(This article belongs to the Section Actuator Materials)
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21 pages, 1587 KiB  
Article
Robotic Arm Position Computing Method in the 2D and 3D Spaces
by Roland Szabo and Radu-Stefan Ricman
Actuators 2023, 12(3), 112; https://doi.org/10.3390/act12030112 - 3 Mar 2023
Cited by 2 | Viewed by 5828
Abstract
This paper presents a method on how to compute the position of a robotic arm in the 2D and 3D spaces. This method is slightly different from the well-known methods, such as forward or inverse kinematics. The method presented in this paper is [...] Read more.
This paper presents a method on how to compute the position of a robotic arm in the 2D and 3D spaces. This method is slightly different from the well-known methods, such as forward or inverse kinematics. The method presented in this paper is an optical method, which uses two video cameras in stereo vision configuration to locate and compute the next move of a robotic arm in space. The method recognizes the coordinates of the markers placed at the joints of the robotic arm using the two video cameras. The coordinate points of these markers are connected with straight lines. Around certain points, circles are drawn. From the tangent to the circles, a non-Cartesian (orthogonal) coordinate system is drawn, which is enough to compute the target position of the robotic arm. All of these drawings are overlaid on the live video feed. This paper also presents another method for calculating the stereo distance using the triangulation method. An alternative method is also presented when a non-Cartesian (orthogonal) 3D coordinate system is created, which is used to compute the target position of the robotic arm in the 3D space. Because the system is in a loop, it can make micro-adjustments of the robotic arm, in order to be exactly in the desired position. In this way, there is no need to make calibrations for the robotic arm. In an industrial system, there is no need to stop the production line, which can be a really big cost saver. Full article
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20 pages, 4651 KiB  
Article
An Observer-Driven Distributed Consensus Braking Control Method for Urban Railway Trains with Unknown Disturbances
by Bin Chen, Rui Zhang, Feng Zhou and Wei Du
Actuators 2023, 12(3), 111; https://doi.org/10.3390/act12030111 - 3 Mar 2023
Cited by 6 | Viewed by 1590
Abstract
An urban railway train is a braking power-distributed system consisting of multiple carriages, which is becoming a powerful transportation tool to alleviate traffic congestion within cities as well as across cities. It is critical to control an urban railway train synchronously for improving [...] Read more.
An urban railway train is a braking power-distributed system consisting of multiple carriages, which is becoming a powerful transportation tool to alleviate traffic congestion within cities as well as across cities. It is critical to control an urban railway train synchronously for improving braking performances, but challenging to be achieved due to strong coupling, unknown dynamics, and disturbances. This paper proposes an observer-driven distributed consensus braking control method for an urban railway train. Specifically, according to the data intersection among carriages, a distributed consensus braking controller is designed to make the velocity of each carriage converge to the desired braking curve. A sliding mode disturbance observer is then developed to estimate the non-linear coupling force and disturbances. The estimation value is utilized to compensate for the distributed consensus braking control law. Moreover, the potential fields are introduced to guarantee that the distances between any two neighbouring carriages are stabilized in a safe range. The effectiveness of the developed control strategy is firstly authenticated via the Lyapunov stability theory and then validated via numerical comparative simulations. Full article
(This article belongs to the Section Control Systems)
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16 pages, 6041 KiB  
Article
Research on Self-Recovery Control Algorithm of Quadruped Robot Fall Based on Reinforcement Learning
by Guichen Zhang, Hongwei Liu, Zihao Qin, Georgy V. Moiseev and Jianwen Huo
Actuators 2023, 12(3), 110; https://doi.org/10.3390/act12030110 - 1 Mar 2023
Cited by 4 | Viewed by 2845
Abstract
When a quadruped robot is climbing stairs, due to unexpected factors, such as the size of the differing from the international standard or the stairs being wet and slippery, it may suddenly fall down. Therefore, solving the self-recovery problem of the quadruped robot [...] Read more.
When a quadruped robot is climbing stairs, due to unexpected factors, such as the size of the differing from the international standard or the stairs being wet and slippery, it may suddenly fall down. Therefore, solving the self-recovery problem of the quadruped robot after falling is of great significance in practical engineering. This is inspired by the self-recovery of crustaceans when they fall; the swinging of their legs will produce a resonance effect of a specific body shape, and then the shell will swing under the action of external force, and self-recovery will be achieved by moving the center of gravity. Based on the bionic mechanism, the kinematics model of a one-leg swing and the self-recovery motion model of a falling quadruped robot are established in this paper. According to the established mathematical model, the algorithm training environment is constructed, and a control strategy based on the reinforcement learning algorithm is proposed as a controller to be applied to the fall self-recovery of quadruped robots. The simulation results show that the quadruped robot only takes 2.25 s to achieve self-recovery through DDPG on flat terrain. In addition, we compare the proposed algorithm with PID and LQR algorithms, and the simulation experiments verify the superiority of the proposed algorithm. Full article
(This article belongs to the Section Actuators for Robotics)
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21 pages, 6784 KiB  
Article
Reinforcement Learning-Based Control of Single-Track Two-Wheeled Robots in Narrow Terrain
by Qingyuan Zheng, Yu Tian, Yang Deng, Xianjin Zhu, Zhang Chen and Bing Liang
Actuators 2023, 12(3), 109; https://doi.org/10.3390/act12030109 - 28 Feb 2023
Cited by 2 | Viewed by 2388
Abstract
The single-track two-wheeled (STTW) robot has the advantages of small size and flexibility, and it is suitable for traveling in narrow terrains of mountains and jungles. In this article, a reinforcement learning control method for STTW robots is proposed for driving fast in [...] Read more.
The single-track two-wheeled (STTW) robot has the advantages of small size and flexibility, and it is suitable for traveling in narrow terrains of mountains and jungles. In this article, a reinforcement learning control method for STTW robots is proposed for driving fast in narrow terrain with limited visibility and line-of-sight occlusions. The proposed control scheme integrates path planning, trajectory tracking, and balancing control in a single framework. Based on this method, the state, action, and reward function are defined for narrow terrain passing tasks. At the same time, we design the actor network and the critic network structures and use the twin delayed deep deterministic policy gradient (TD3) to train these neural networks to construct a controller. Next, a simulation platform is formulated to test the performances of the proposed control method. The simulation results show that the obtained controller allows the STTW robot to effectively pass the training terrain, as well as the four test terrains. In addition, this article conducts a simulation comparison to prove the advantages of the integrated framework over traditional methods and the effectiveness of the reward function. Full article
(This article belongs to the Special Issue Advanced Technologies and Applications in Robotics)
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17 pages, 5829 KiB  
Article
Hybrid Inspection Robot for Indoor and Outdoor Surveys
by Pierluigi Rea and Erika Ottaviano
Actuators 2023, 12(3), 108; https://doi.org/10.3390/act12030108 - 27 Feb 2023
Cited by 2 | Viewed by 3616
Abstract
In this paper, simulation and experimental tests are reported for a hybrid robot being used for indoor and outdoor inspections. Automatic or tele-operated surveys can be performed by mobile robots, which represent the most efficient solution in terms of power consumption, control, robustness, [...] Read more.
In this paper, simulation and experimental tests are reported for a hybrid robot being used for indoor and outdoor inspections. Automatic or tele-operated surveys can be performed by mobile robots, which represent the most efficient solution in terms of power consumption, control, robustness, and overall costs. In the context of structures and infrastructure inspection, robots must be able to move on horizontal or sloped surfaces and overpass obstacles. In this paper, the mechatronic design, simulations, and experimental activity are proposed for a hybrid robot being used for indoor and outdoor inspections, when the environmental conditions do not allow autonomous navigation. In particular, the hybrid robot is equipped with external and internal sensors to acquire information on the main structural elements, avoiding the need for experienced personnel being directly inside the inspection site, taking information from the environment and aiding the pilot to understand the best maneuvers/decisions to take. Given the current state of research and shortcomings worldwide, this paper discusses inspection robots taking into account the main issues in their use, functionality and standard systems, and how internal sensors can be set in order to improve inspection robots’ performances. On this basis, an illustrative study case is proposed. Full article
(This article belongs to the Special Issue Actuators in 2022)
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20 pages, 4804 KiB  
Article
Automatic Calibration of Tool Center Point for Six Degree of Freedom Robot
by Chih-Jer Lin, Hsing-Cheng Wang and Cheng-Chi Wang
Actuators 2023, 12(3), 107; https://doi.org/10.3390/act12030107 - 27 Feb 2023
Cited by 5 | Viewed by 5287
Abstract
The traditional tool center point (TCP) calibration method requires the operator to use their experience to set the actual position of the tool center point. To address this lengthy workflow and low accuracy, while improving accuracy and efficiency for time-saving and non-contact calibration, [...] Read more.
The traditional tool center point (TCP) calibration method requires the operator to use their experience to set the actual position of the tool center point. To address this lengthy workflow and low accuracy, while improving accuracy and efficiency for time-saving and non-contact calibration, this paper proposes an enhanced automatic TCP calibration method based on a laser displacement sensor and implemented on a cooperative robot with six degrees of freedom. During the calibration process, the robot arm will move a certain distance along the X and Y axes and collect the information when the tool passes through the laser during the process to calculate the runout of the tool, and then continue to move a certain distance along the X and Y axes for the second height calibration. After the runout angle is calculated and calibrated by triangulation, the runout calibration is completed and the third X and Y axis displacement is performed to find out the exact position of the tool on the X and Y axes. Finally, the tool is moved to a position higher than the laser, and the laser is triggered by moving downward to obtain information to complete the whole experimental process and receive the calibrated tool center position. The whole calibration method is, firstly, verified in the virtual simulation environment and then implemented on the actual cooperative robot. The results of the proposed TCP calibration method for the case of using a pin tool can achieve a positioning deviation of 0.074 and 0.125 mm for the robot moving speeds of 20 and 40 mm/s, respectively. The orientation deviation in the x-axis are 0.089 and −0.184 degrees for the robot moving speeds of 20 and 40 mm/s, respectively. The positioning repeatability of ±0.083 mm for the moving speed of 20 mm/s is lower than ±0.101 mm for the speed of 40 mm/s. It shows that lower moving speed can obtain higher accuracy and better repeatability. This result meets the requirements of TCP calibration but also achieves the purpose of being simple, economical, and time-saving, and it takes only 60 s to complete the whole calibration process. Full article
(This article belongs to the Special Issue Actuators in Robotic Control—2nd Edition)
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22 pages, 14760 KiB  
Article
Development of Autonomous Driving and Motion Control System for a Patient Transfer Robot
by Changwon Kim and Chan-Jung Kim
Actuators 2023, 12(3), 106; https://doi.org/10.3390/act12030106 - 26 Feb 2023
Cited by 3 | Viewed by 2764
Abstract
In this study, an autonomous driving system of a patient-transfer robot is developed. The developed autonomous driving system has a path-planning module and a motion-control module. Since the developed autonomous driving system is applied to medical robots, such as patient-transfer robots, the main [...] Read more.
In this study, an autonomous driving system of a patient-transfer robot is developed. The developed autonomous driving system has a path-planning module and a motion-control module. Since the developed autonomous driving system is applied to medical robots, such as patient-transfer robots, the main purpose of this study is to generate an optimal path for the robot’s movement and to ensure the patient on board moves comfortably in the PTR. In particular, for the patient’s comfortable movement, a lower controller is needed to minimize the sway angle of the patient. In this paper, we propose a hybrid path-planning algorithm that combines the A-STAR algorithm as a global path-planning method and the AHP (Analytic Hierarchy Process)-based path-planning algorithm as a local path-planning method. In addition, model-based controllers are designed to move patient-transport robots along planned paths. In particular, the LQR controller with the Kalman filter is designed to be robust to the uncertainty and disturbance of the model including the patient. The optimal path generation and patient shaking angle reduction performance of the proposed autonomous driving system have been demonstrated via a simulation on a map that mimics a hospital environment. Full article
(This article belongs to the Special Issue Actuators in 2022)
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