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Actuators
Volume 13
Issue 6
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Actuators, Volume 13, Issue 6 (June 2024) – 37 articles

Cover Story (view full-size image): This paper presents a novel design for humanoid arm mechanisms, with a tripod parallel architecture actuated by linear motors. The design is validated with experimental tests on a prototype to characterize its performance and check its feasibility for implementation in the LARMbot humanoid robot. The design proves successful with a large, singularity-free workspace and a high payload to arm weight ratio. Furthermore, the prototype can be assembled with low-cost commercial components while still maintaining good motion and force performance for the successful integration with the LARMbot design. View this paper
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17 pages, 5502 KiB  
Article
Research on Intelligent Wheelchair Multimode Human–Computer Interaction and Assisted Driving Technology
by Jianwei Cui, Yucheng Shang, Siji Yu and Yuanbo Wang
Actuators 2024, 13(6), 230; https://doi.org/10.3390/act13060230 - 20 Jun 2024
Viewed by 236
Abstract
The traditional wheelchair focuses on the “human-chair” motor function interaction to ensure the elderly and people with disabilities’ basic travel. For people with visual, hearing, physical disabilities, etc., the current wheelchairs show shortcomings in terms of accessibility and independent travel for this group. [...] Read more.
The traditional wheelchair focuses on the “human-chair” motor function interaction to ensure the elderly and people with disabilities’ basic travel. For people with visual, hearing, physical disabilities, etc., the current wheelchairs show shortcomings in terms of accessibility and independent travel for this group. Therefore, this paper develops an intelligent wheelchair with multimodal human–computer interaction and autonomous navigation technology. Firstly, it researches the multimodal human–computer interaction technology of occupant gesture recognition, speech recognition, and head posture recognition and proposes a wheelchair control method of three-dimensional head posture mapping the two-dimensional plane. After testing, the average accuracy of the gesture, head posture and voice control modes of the motorized wheelchair proposed in this study reaches more than 95 percent. Secondly, the LiDAR-based smart wheelchair indoor autonomous navigation technology is investigated to realize the autonomous navigation of the wheelchair by constructing an environment map, using A* and DWA algorithms for global and local path planning, and adaptive Monte Carlo simulation algorithms for real-time localization. Experiments show that the position error of the wheelchair is within 10 cm, and the heading angle error is less than 5° during the autonomous navigation. The multimode human–computer interaction and assisted driving technology proposed in this study can partially compensate and replace the functional deficiencies of the disabled population and improve the quality of life of the elderly and disabled population. Full article
(This article belongs to the Special Issue Rehabilitation Robots and Assistive Devices: A Special Issue in Honor of Prof. Dr. Rory A. Cooper)
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15 pages, 4581 KiB  
Article
Gust Load Alleviation Control Strategies for Large Civil Aircraft through Wing Camber Technology
by Shanshan Zhang, Yueheng Qiu, Junshuai Sun, Ban Wang and Zhenghong Gao
Actuators 2024, 13(6), 229; https://doi.org/10.3390/act13060229 - 20 Jun 2024
Viewed by 326
Abstract
This paper introduces three new gust load alleviation control strategies, which are based on variable camber technology, to achieve the design requirements for the safety, economy, and comfort of modern civil aircraft. These strategies involve adjusting the inner and outer flap differential of [...] Read more.
This paper introduces three new gust load alleviation control strategies, which are based on variable camber technology, to achieve the design requirements for the safety, economy, and comfort of modern civil aircraft. These strategies involve adjusting the inner and outer flap differential of wings, spoilers, and ailerons to alter the aerodynamic shape of the aircraft structure, resulting in drag reduction and gust load alleviation during stepped cruise flights. Furthermore, a logic design is provided for both the cruise drag reduction function and the gust load alleviation function. To validate the effectiveness of the proposed gust load alleviation control strategies, simulation results are presented, utilizing ride quality and wing root bending moment changes as the evaluation criteria. The presented approaches ultimately lead to the development of an optimal scheme that meets the desired design requirements. Full article
(This article belongs to the Special Issue Flight Control Systems and Dynamic Simulation for Aerospace Applications)
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27 pages, 13269 KiB  
Article
The Design and Application of a Vectored Thruster for a Negative Lift-Shaped AUV
by Hong Zhu, Lunyang Lin, Chunliang Yu, Yuxiang Chen, Hong Xiong, Yiyang Xing and Guodong Zheng
Actuators 2024, 13(6), 228; https://doi.org/10.3390/act13060228 - 19 Jun 2024
Viewed by 211
Abstract
Autonomous underwater vehicles (AUVs), as primary platforms, have significantly contributed to underwater surveys in scientific and military fields. Enhancing the maneuverability of autonomous underwater vehicles is crucial to their development. This study presents a novel vectored thruster and an optimized blade design approach [...] Read more.
Autonomous underwater vehicles (AUVs), as primary platforms, have significantly contributed to underwater surveys in scientific and military fields. Enhancing the maneuverability of autonomous underwater vehicles is crucial to their development. This study presents a novel vectored thruster and an optimized blade design approach to meet the design requirements of a specially shaped AUV. Determining the ideal blade characteristics involves selecting a maximum diameter of 0.18 m and configuring the number of blades to be four. Furthermore, the blades of the AUV were set to rotate at a speed of 1400 revolutions per minute (RPM). The kinematics of the thrust-vectoring mechanism was theoretically analyzed. A propulsive force test of the vectored thruster with ductless and ducted propellers was performed to evaluate its performance. A ductless propeller without an annular wing had a higher propulsive efficiency with a maximum thrust of 115 N. Open-loop control was applied to an AUV in a water tank, exhibiting a maximum velocity of 0.98 m/s and a pitch angle of 53°. The maximum rate of heading angle was 14.26°/s. The test results demonstrate that the specially designed thrust-vectoring mechanism notably enhances the effectiveness of AUVs at low forward speeds. In addition, tests conducted in offshore waters for depth and heading control validated the vectored thruster’s capability to fulfill the AUV’s motion control requirements. Full article
(This article belongs to the Special Issue Advanced Robots: Design, Control and Application—2nd Edition)
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23 pages, 5628 KiB  
Article
Research on an Ice Tolerance Control Method for Large Aircraft Based on Adaptive Dynamic Inversion
by Feihong Jiang, Xiaoxiong Liu, Tongwen Chen and Kecheng Li
Actuators 2024, 13(6), 227; https://doi.org/10.3390/act13060227 - 18 Jun 2024
Viewed by 277
Abstract
Considering the effect of icing on aircraft control performance, this paper proposes an adaptive dynamic inverse ice tolerance control method based on piecewise constant. A control allocation algorithm is introduced to compensate for the change of control surface performance caused by icing. This [...] Read more.
Considering the effect of icing on aircraft control performance, this paper proposes an adaptive dynamic inverse ice tolerance control method based on piecewise constant. A control allocation algorithm is introduced to compensate for the change of control surface performance caused by icing. This method can achieve satisfactory disturbance estimation accuracy under a given sampling time, and thus ensure a closed-loop system error within an acceptable range. The proposed design method is applied to the design of a flight control law for a transport aircraft, aiming to solve the problem of ice-tolerant flight control, reduce the influence of icing conditions on controllability and safe flight of the transport aircraft, and thus improve the flight quality of the transport aircraft. The simulation results are verified under the influence of both standby ice type and failure ice type, and the interference effect on aircraft aerodynamic parameters is further added. The simulation results show that adaptive dynamic inverse control based on piecewise constant can overcome the influence caused by icing and aerodynamic parameter interference, achieve accurate tracking of command, and provide excellent fault tolerance and robustness, which ensures that the transport aircraft can achieve the desired control performance and safe flight capability. Full article
(This article belongs to the Special Issue Fault-Tolerant Control for Unmanned Aerial Vehicles (UAVs))
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20 pages, 7763 KiB  
Article
Comparative Experimental Study on the De-Icing Performance of Multiple Actuators
by Jiajun Zhang, Hua Liang, Biao Wei, Dongliang Bian, Shimin Liu and Hongrui Liu
Actuators 2024, 13(6), 226; https://doi.org/10.3390/act13060226 - 17 Jun 2024
Viewed by 263
Abstract
The issue of aircraft icing poses a substantial threat to flight safety. In order to investigate more efficient anti-icing and de-icing technologies, a comparative analysis was conducted on the de-icing characteristics of three types of actuator materials under varying conditions. Initially, experimental research [...] Read more.
The issue of aircraft icing poses a substantial threat to flight safety. In order to investigate more efficient anti-icing and de-icing technologies, a comparative analysis was conducted on the de-icing characteristics of three types of actuator materials under varying conditions. Initially, experimental research was undertaken to analyze the temperature traits of three actuators under ice-free conditions. Three power densities were chosen for the experiment: 0.170 W/cm2, 0.727 W/cm2, and 1.427 W/cm2. The research findings revealed distinct characteristics: plasma actuators and resistance wire actuators exhibited a strip-like high-temperature region during operation, with well-defined boundaries between the high-temperature and low-temperature zones, whereas ceramic-based semiconductor actuators showcased a uniform high-temperature region. As energy consumption rose, the thermal equilibrium temperatures of all three types tended to converge, with resistance wire actuators operating at 1.427 W/cm2, showing the highest temperature rise rate at that power density. Subsequently, experimental research was carried out on the de-icing performance of three actuators under icing conditions at a specific power density. Following 120 s of de-icing, the ice layer covering the surface of the plasma actuator completely melted, forming a cavity. Conversely, the ice layer on the ceramic-based semiconductor actuator remained partially intact in a strip shape. Ice deposits were still visible on the surface of the resistance wire actuator. This observation highlights the remarkable de-icing speed of the plasma actuator. The propulsive force of plasma generated on the fluid inside the ice layer enhances heat transfer efficiency, thereby accelerating the de-icing process of the plasma actuator at the same power density. The analysis of the de-icing performance of these three novel types of actuators establishes a robust groundwork for exploring more effective aircraft de-icing methods. Furthermore, it furnishes theoretical underpinning for the advancement of composite anti-icing and de-icing strategies. Full article
(This article belongs to the Special Issue Electrohydrodynamic Plasma Actuator for Active Flow Control: From Micropumps to Space Thrusters)
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20 pages, 3401 KiB  
Article
Incremental Nonlinear Dynamics Inversion and Incremental Backstepping: Experimental Attitude Control of a Tail-Sitter UAV
by Alexandre Athayde, Alexandra Moutinho and José Raul Azinheira
Actuators 2024, 13(6), 225; https://doi.org/10.3390/act13060225 - 17 Jun 2024
Viewed by 267
Abstract
Incremental control strategies such as Incremental Nonlinear Dynamics Inversion (INDI) and Incremental Backstepping (IBKS) provide undeniable advantages for controlling Uncrewed Aerial Vehicles (UAVs) due to their reduced model dependency and accurate tracking capacities, which is of particular relevance for tail-sitters as these perform [...] Read more.
Incremental control strategies such as Incremental Nonlinear Dynamics Inversion (INDI) and Incremental Backstepping (IBKS) provide undeniable advantages for controlling Uncrewed Aerial Vehicles (UAVs) due to their reduced model dependency and accurate tracking capacities, which is of particular relevance for tail-sitters as these perform complex, hard to model manoeuvres when transitioning to and from aerodynamic flight. In this research article, a quaternion-based form of IBKS is originally deduced and applied to the stabilization of a tail-sitter in vertical flight, which is then implemented in a flight controller and validated in a Hardware-in-the-Loop simulation, which is also made for the INDI controller. Experimental validation with indoor flight tests of both INDI and IBKS controllers follows, evaluating their performance in stabilizing the tail-sitter prototype in vertical flight. Lastly, the tracking results obtained from the experimental trials are analysed, allowing an objective comparison to be drawn between these controllers, evaluating their respective advantages and limitations. From the successfully conducted flight tests, it was found that both incremental solutions are suited to control a tail-sitter in vertical flight, providing accurate tracking capabilities with smooth actuation, and only requiring the actuation model. Furthermore, it was found that the IBKS is significantly more computationally demanding than the INDI, although having a global proof of stability that is of interest in aircraft control. Full article
(This article belongs to the Special Issue From Theory to Practice: Incremental Nonlinear Control)
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19 pages, 16845 KiB  
Article
The Structure-Dependent Dynamic Performance of a Twin-Ball-Screw Drive Mechanism via a Receptance Coupling Approach
by Uwayezu Marie Chantal, Hong Lu, Qi Liu, Tao Jiang, Jiji He, Shuaiwei Gu and Gashema Gaspard
Actuators 2024, 13(6), 224; https://doi.org/10.3390/act13060224 - 15 Jun 2024
Viewed by 350
Abstract
The drive at the center of gravity (DCG) concept-based twin-ball-screw drive mechanism (TBSDM) is vital in automated factories for its robustness and reliability. However, changes in the worktable mass or position result in changes in the center of gravity (CG), significantly affecting the [...] Read more.
The drive at the center of gravity (DCG) concept-based twin-ball-screw drive mechanism (TBSDM) is vital in automated factories for its robustness and reliability. However, changes in the worktable mass or position result in changes in the center of gravity (CG), significantly affecting the system’s dynamic properties. In this regard, this paper introduces a novel analytical model using improved receptance coupling to analyze vibrations in four modes. A mathematical framework for the twin TBSDM is generated, and the effect of changing the worktable position–mass on each mode is examined. The applicability of the proposed method is verified based on dynamic experiments that were carried out on a TBSDM of a CNC grinding wheel machine tool. After thoroughly analyzing the experimental and theoretical results, it is revealed that changing the worktable position primarily influences the rotational and axial vibrations of the twin ball screw (TBS). Furthermore, changes in the worktable mass significantly affect the coupling vibration among the TBSs and rotors or bearings. Moreover, in terms of performance, the variances between the theoretical and experimental natural frequencies are consistently below 5%. Thus, the proposed method is promising for the improvement of the modeling and analysis of the TBSDM. Full article
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20 pages, 997 KiB  
Article
Image-Based Visual Servoing for Three Degree-of-Freedom Robotic Arm with Actuator Faults
by Jiashuai Li, Xiuyan Peng, Bing Li, Mingze Li and Jiawei Wu
Actuators 2024, 13(6), 223; https://doi.org/10.3390/act13060223 - 13 Jun 2024
Viewed by 316
Abstract
This study presents a novel image-based visual servoing fault-tolerant control strategy aimed at ensuring the successful completion of visual servoing tasks despite the presence of robotic arm actuator faults. Initially, a depth-independent image-based visual servoing model is established to mitigate the effects of [...] Read more.
This study presents a novel image-based visual servoing fault-tolerant control strategy aimed at ensuring the successful completion of visual servoing tasks despite the presence of robotic arm actuator faults. Initially, a depth-independent image-based visual servoing model is established to mitigate the effects of inaccurate camera parameters and missing depth information on the system. Additionally, a robotic arm dynamic model is constructed, which simultaneously considers both multiplicative and additive actuator faults. Subsequently, model uncertainties, unknown disturbances, and coupled actuator faults are consolidated as centralized uncertainties, and an iterative learning fault observer is designed to estimate them. Based on this, suitable sliding surfaces and control laws are developed within the super-twisting sliding mode visual servo controller to rapidly reduce control deviation to near zero and circumvent the chattering phenomenon typically observed in traditional sliding mode control. Finally, through comparative simulation between different control strategies, the proposed method is shown to effectively counteract the effect of actuator faults and exhibit robust performance. Full article
(This article belongs to the Section Actuators for Robotics)
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17 pages, 5822 KiB  
Article
Fault Detection of Flow Control Valves Using Online LightGBM and STL Decomposition
by Shaodong Liu, Tao Zhao and Dengfeng Zhang
Actuators 2024, 13(6), 222; https://doi.org/10.3390/act13060222 - 13 Jun 2024
Viewed by 319
Abstract
In the process industrial systems, flow control valves are deemed vital components that ensure the system’s safe operation. Hence, detecting faults in control valves is of significant importance. However, the stable operating conditions of flow control valves are prone to change, resulting in [...] Read more.
In the process industrial systems, flow control valves are deemed vital components that ensure the system’s safe operation. Hence, detecting faults in control valves is of significant importance. However, the stable operating conditions of flow control valves are prone to change, resulting in a decreased effectiveness of the conventional fault detection method. In this paper, an online fault detection approach considering the variable operating conditions of flow control valves is proposed. This approach is based on residual analysis, combining LightGBM online model with Seasonal and Trend decomposition using Loess (STL). LightGBM is a tree-based machine learning algorithm. In the proposed method, an online LightGBM is employed to establish and continuously update a flow prediction model for control valves, ensuring model accuracy during changes in operational conditions. Subsequently, STL decomposition is applied to the model’s residuals to capture the trend of residual changes, which is then transformed into a Health Index (HI) for evaluating the health level of the flow control valves. Finally, fault occurrences are detected based on the magnitude of the HI. We validate this approach using both simulated and real factory data. The experimental results demonstrate that the proposed method can promptly reflect the occurrence of faults through the HI. Full article
(This article belongs to the Special Issue AI, Designing, Sensing, Instrumentation, Diagnosis, Controlling, and Integration of Actuators in Digital Manufacturing—Volume II)
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21 pages, 7819 KiB  
Article
Research on the Deviation Correction Control of a Tracked Drilling and Anchoring Robot in a Tunnel Environment
by Chuanwei Wang, Hongwei Ma, Xusheng Xue, Qinghua Mao, Jinquan Song, Rongquan Wang and Qi Liu
Actuators 2024, 13(6), 221; https://doi.org/10.3390/act13060221 - 13 Jun 2024
Viewed by 291
Abstract
In response to the challenges of multiple personnel, heavy support tasks, and high labor intensity in coal mine tunnel drilling and anchoring operations, this study proposes a novel tracked drilling and anchoring robot. The robot is required to maintain alignment with the centerline [...] Read more.
In response to the challenges of multiple personnel, heavy support tasks, and high labor intensity in coal mine tunnel drilling and anchoring operations, this study proposes a novel tracked drilling and anchoring robot. The robot is required to maintain alignment with the centerline of the tunnel during operation. However, owing to the effects of skidding and slipping between the track mechanism and the floor, the precise control of a drilling and anchoring robot in tunnel environments is difficult to achieve. Through an analysis of the body and track mechanisms of the drilling and anchoring robot, a kinematic model reflecting the pose, steering radius, steering curvature, and angular velocity of the drive wheel of the drilling and anchoring robot was established. This facilitated the determination of speed control requirements for the track mechanism under varying driving conditions. Mathematical models were developed to describe the relationships between a tracked drilling and anchoring robot and several key factors in tunnel environments, including the minimum steering space required by the robot, the minimum relative steering radius, the steering angle, and the lateral distance to the sidewalls. Based on these models, deviation-correction control strategies were formulated for the robot, and deviation-correction path planning was completed. In addition, a PID motion controller was developed for the robot, and trajectory-tracking control simulation experiments were conducted. The experimental results indicate that the tracked drilling and anchoring robot achieves precise control of trajectory tracking, with a tracking error of less than 0.004 m in the x-direction from the tunnel centerline and less than 0.001 m in the y-direction. Considering the influence of skidding, the deviation correction control performance test experiments of the tracked drilling and anchoring robot at dy = 0.5 m away from the tunnel centerline were completed. In the experiments, the tracked drilling and anchoring robot exhibited a significant difference in speed between the two sides of the tracks with a track skid rate of 0.22. Although the real-time tracking maximum error in the y-direction from the tunnel centerline was 0.13 m, the final error was 0.003 m, meeting the requirements for position deviation control of the drilling and anchoring robot in tunnel environments. These research findings provide a theoretical basis and technical support for the intelligent control of tracked mobile devices in coal mine tunnels, with significant theoretical and engineering implications. Full article
(This article belongs to the Special Issue Advanced Robots: Design, Control and Application—2nd Edition)
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19 pages, 7824 KiB  
Article
Impedance Learning-Based Hybrid Adaptive Control of Upper Limb Rehabilitation Robots
by Zhenhua Jiang, Zekai Wang, Qipeng Lv and Jiantao Yang
Actuators 2024, 13(6), 220; https://doi.org/10.3390/act13060220 - 12 Jun 2024
Viewed by 320
Abstract
This paper presents a hybrid adaptive control strategy for upper limb rehabilitation robots using impedance learning. The hybrid adaptation consists of a differential updating mechanism for the estimation of robotic modeling uncertainties and periodic adaptations for the online learning of time-varying impedance. The [...] Read more.
This paper presents a hybrid adaptive control strategy for upper limb rehabilitation robots using impedance learning. The hybrid adaptation consists of a differential updating mechanism for the estimation of robotic modeling uncertainties and periodic adaptations for the online learning of time-varying impedance. The proposed hybrid adaptive controller guarantees asymptotical control stability and achieves variable impedance regulation for robots without interaction force measurements. According to Lyapunov’s theory, we proved that the proposed impedance learning controller guarantees the convergence of tracking errors and ensures the boundedness of the estimation errors of robotic uncertainties and impedance profiles. Simulations and experiments conducted on a parallel robot validated the effectiveness and the superiority of the proposed impedance learning controller in robot-assisted rehabilitation. The proposed hybrid adaptive control has potential applications in rehabilitation, exoskeletons, and some other repetitive interactive tasks. Full article
(This article belongs to the Section Actuators for Medical Instruments)
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23 pages, 5168 KiB  
Article
Calibration Optimization of Kinematics and Dynamics for Delta Robot Driven by Integrated Joints in Machining Task
by Zhenhua Jiang, Yu Wang, Dongdong Liu and Tao Sun
Actuators 2024, 13(6), 219; https://doi.org/10.3390/act13060219 - 12 Jun 2024
Viewed by 315
Abstract
For the application of Delta robots with a 3-R(RPaR) configuration in machining tasks, this paper constructed a 54-parameter kinematic error model and a simplified dynamic model incorporating an integrated joint’s position error and friction, respectively. Utilizing Singular Value Decomposition (SVD) of the Linear [...] Read more.
For the application of Delta robots with a 3-R(RPaR) configuration in machining tasks, this paper constructed a 54-parameter kinematic error model and a simplified dynamic model incorporating an integrated joint’s position error and friction, respectively. Utilizing Singular Value Decomposition (SVD) of the Linear Model Coefficient Matrix (LMCM) and the coefficient chart, a criterion for identifiability of error components is established. For good identification results, the optimal measurement surface with Fourier series form is obtained using a combination of the Hook–Jeeves Direct Search Algorithm (DSA) and Inner Point Method (IPM). The friction coefficients and other dynamic parameters are obtained through fitting the integrated joint torque-angle pairs measured along specific trajectories using nonlinear least squares regression. The validation of the calibration process is conducted through simulations and experiments. The calibration results provide a foundation for the precise control of integrated joints and the high-precision motion of robots. Full article
(This article belongs to the Special Issue Recent Developments in Precision Actuation Technologies)
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17 pages, 4542 KiB  
Article
Reduced Kinematic Error for Position Accuracy in a High-Torque, Lightweight Actuator
by Rajesh Kannan Megalingam, Shree Rajesh Raagul Vadivel, Sakthiprasad Kuttankulangara Manoharan, Bhanu Teja Pula, Sarveswara Reddy Sathi and Uppala Sai Chaitanya Gupta
Actuators 2024, 13(6), 218; https://doi.org/10.3390/act13060218 - 12 Jun 2024
Viewed by 434
Abstract
In this paper, we propose the design, development, and testing of high-torque and lightweight actuators suitable for lightweight robotic applications. The detailed design of the actuator module is described, and its performance evaluation is also presented. Further, the mathematical modelling of the actuator [...] Read more.
In this paper, we propose the design, development, and testing of high-torque and lightweight actuators suitable for lightweight robotic applications. The detailed design of the actuator module is described, and its performance evaluation is also presented. Further, the mathematical modelling of the actuator is discussed. Various performance analysis tests were carried out for the elucidation of the designed actuator, which included primarily position, velocity, and torque analyses. The position accuracy analysis included position repeatability at the maximum payload for calculating the acceptable tolerance. The velocity elucidation included a velocity test for the variable load. The torque analysis of the actuator was completed at different supply currents. These tests and the results indicate that the proposed actuator has high precision in reaching the desired position and provides a stabilized performance with variable loads up to the limit for which it was designed. Based on the torque output and the weight, the proposed actuator could be a good fit for lightweight robotic applications. Full article
(This article belongs to the Section High Torque/Power Density Actuators)
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24 pages, 1291 KiB  
Review
Disturbance Observer and Adaptive Control for Disturbance Rejection of Quadrotor: A Survey
by Ruiying Wang and Jun Shen
Actuators 2024, 13(6), 217; https://doi.org/10.3390/act13060217 - 11 Jun 2024
Viewed by 269
Abstract
Quadrotors are widely applied in many fields, but they often face various external disturbances in actual operation. This makes it necessary to design a controller that can handle disturbances. Disturbance observer and adaptive control techniques are commonly used disturbance rejection techniques, the core [...] Read more.
Quadrotors are widely applied in many fields, but they often face various external disturbances in actual operation. This makes it necessary to design a controller that can handle disturbances. Disturbance observer and adaptive control techniques are commonly used disturbance rejection techniques, the core idea of which is to estimate the disturbances in real time and incorporate the estimated values into the controller to suppress the disturbances. In this paper, various disturbance observers and adaptive control techniques, including nonlinear disturbance observers, extended state observers, neural networks, and fuzzy logic systems, are introduced, along with their variants or different structures. These techniques improve the adaptability and robustness of quadrotors to complex environments. Finally, future research directions for the disturbance rejection of quadrotors are also presented. Full article
(This article belongs to the Section Aircraft Actuators)
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16 pages, 760 KiB  
Article
Dynamic Output Feedback of Second-Order Systems: An Observer-Based Controller with Linear Matrix Inequality Design
by Danielle Gontijo, José Mário Araújo, Luciano Frezzato and Fernando de Oliveira Souza
Actuators 2024, 13(6), 216; https://doi.org/10.3390/act13060216 - 9 Jun 2024
Viewed by 369
Abstract
This paper presents an observer-based dynamic output-feedback controller design procedure using linear matrix inequality (LMI) optimization for second-order systems with uncertainty and persistent perturbation in the states. Using linear-quadratic criteria, cost functions are minimized in a two-stage procedure to compute optimal state-feedback gains, [...] Read more.
This paper presents an observer-based dynamic output-feedback controller design procedure using linear matrix inequality (LMI) optimization for second-order systems with uncertainty and persistent perturbation in the states. Using linear-quadratic criteria, cost functions are minimized in a two-stage procedure to compute optimal state-feedback gains, and observer gains are coupled into a dynamic output-feedback optimal controller. The LMI set used in the two stages is matrix inversion free, a key issue for polytope formulation when uncertainty is present. The approach is tested in a mobile inverted pendulum robotic platform, and the effectiveness is verified in this underactuated and undesensed case. Full article
(This article belongs to the Special Issue Dynamics and Control of Underactuated Systems)
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25 pages, 10182 KiB  
Article
Motion Control of a Hybrid Quadruped-Quadrotor Robot
by Wenjuan Ouyang, Haozhen Chi, Leifeng Lu, Chao Wang and Qinyuan Ren
Actuators 2024, 13(6), 215; https://doi.org/10.3390/act13060215 - 9 Jun 2024
Viewed by 313
Abstract
Multimodal motion capability is an emerging topic in the robotics field, and this paper presents a hybrid robot system maneuvering in both terrestrial and aerial environments. Firstly, a micro quadruped–quadrotor robot with onboard sensing and computing is developed. This robot incorporates both the [...] Read more.
Multimodal motion capability is an emerging topic in the robotics field, and this paper presents a hybrid robot system maneuvering in both terrestrial and aerial environments. Firstly, a micro quadruped–quadrotor robot with onboard sensing and computing is developed. This robot incorporates both the high mobility of unmanned aerial vehicles and the long endurance of mobile robots on the ground. A coordinated motion control scheme is then exploited for adaptive terrestrial–aerial motion transition. In this scheme, a bio-inspired terrestrial locomotion controller is proposed to generate various quadruped locomotions, and a model-based aerial locomotion controller is proposed to generate various quadrotor configurations. Then, an unified motion controller for the two subsystems which dynamically adjusts crawling and flying motion in a complicated environment is presented. Consequently, several practical trials are conducted to demonstrate the adaptability and the robustness of the proposed system. Full article
(This article belongs to the Section Actuators for Robotics)
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21 pages, 9698 KiB  
Article
Soft Electrohydraulic Bending Actuators for Untethered Underwater Robots
by Hao Lin, Yihui Chen and Wei Tang
Actuators 2024, 13(6), 214; https://doi.org/10.3390/act13060214 - 8 Jun 2024
Viewed by 396
Abstract
Traditional underwater rigid robots have some shortcomings that limit their applications in the ocean. In contrast, because of their inherent flexibility, soft robots, which have gained popularity recently, offer greater adaptability, efficiency, and safety than rigid robots. Among them, the soft actuator is [...] Read more.
Traditional underwater rigid robots have some shortcomings that limit their applications in the ocean. In contrast, because of their inherent flexibility, soft robots, which have gained popularity recently, offer greater adaptability, efficiency, and safety than rigid robots. Among them, the soft actuator is the core component to power the soft robot. Here, we propose a class of soft electrohydraulic bending actuators suitable for underwater robots, which realize the bending motion of the actuator by squeezing the working liquid with an electric field. The actuator consists of a silicone rubber film, polydimethylsiloxane (PDMS) films, soft electrodes, silicone oils, an acrylic frame, and a soft flipper. When a square wave voltage is applied, the actuator can generate continuous flapping motions. By mimicking Haliclystus auricula, we designed an underwater robot based on six soft electrohydraulic bending actuators and constructed a mechanical model of the robot. Additionally, a high-voltage square wave circuit board was created to achieve the robot’s untethered motions and remote control using a smart phone via WiFi. The test results show that 1 Hz was the robot’s ideal driving frequency, and the maximum horizontal swimming speed of the robot was 7.3 mm/s. Full article
(This article belongs to the Special Issue Soft Robotics: Actuation, Control, and Application)
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21 pages, 14849 KiB  
Article
Numerical Study on the Internal Flow Field Characteristics of a Novel High-Speed Switching Control Valve
by Hexi Ji, Jiazhen Han, Yong Wang, Qixian Wang, Sen Yang, Yudong Xie, Yilong Song and Haibo Wang
Actuators 2024, 13(6), 213; https://doi.org/10.3390/act13060213 - 6 Jun 2024
Viewed by 293
Abstract
Modern laver fluffiness is achieved by applying high-speed gas to a laver, which is generated by the opening and closing of a laver fluffiness control valve in a fluffiness system. To address the problems of the slow response speed and poor stability of [...] Read more.
Modern laver fluffiness is achieved by applying high-speed gas to a laver, which is generated by the opening and closing of a laver fluffiness control valve in a fluffiness system. To address the problems of the slow response speed and poor stability of valves used in the laver processing industry at present, this paper proposes a novel principle of a high-speed switching control valve, which has the advantages of a fast response speed, high stability, and long service life. The structure and working principle of the control valve are introduced, and the calculation equation of the valve’s flow area is established. The flow field inside the control valve with different openings was numerically calculated in this study using Fluent. The flow regulation characteristics and flow field performance of the control valve were also analyzed. The results show that, with an increase in the valve opening, the influence of the flow area at the valve throttle on the valve flow rate was weakened. When the valve was opened, a vortex appeared in both the upper and lower cavities, and jet flow occurred at the throttle of the middle flow channel. As the valve opening increased, the pressure in the upper cavity reduced, while the pressure in the lower cavity increased. The vortex in the flow field intensified, and the jet phenomenon at the valve throttle gradually disappeared. At the same time, the main stream in the lower cavity gradually changed from an annular flow to a direct flow toward the valve outlet. Furthermore, the impact, collision, and vortex formation of the fluid caused energy loss of the fluid, leading to a decrease in the outlet flow of the control valve. Full article
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13 pages, 6211 KiB  
Article
Active Power Assist with Equivalent Force on Connection for Lower Limb Exoskeleton Robots
by Jing Deng, Wenzheng Jiang, Haibo Gao, Mantian Li and Yapeng Shi
Actuators 2024, 13(6), 212; https://doi.org/10.3390/act13060212 - 5 Jun 2024
Viewed by 330
Abstract
Active power-assist lower limb exoskeleton robots aim to enhance wearer assistance while ensuring wearer comfort and simplifying the exoskeleton’s design and control. This study proposes an active assistance method known as Equivalent Force on Connection (EFOC). The EFOC method effectively addresses the limitations [...] Read more.
Active power-assist lower limb exoskeleton robots aim to enhance wearer assistance while ensuring wearer comfort and simplifying the exoskeleton’s design and control. This study proposes an active assistance method known as Equivalent Force on Connection (EFOC). The EFOC method effectively addresses the limitations encountered in conventional Joint Torque Proportional Compensation (JTPC) approaches. These limitations include the necessity for exoskeleton robot configurations to align with human limb structures for parallel assistance at each lower limb joint, as well as the exoskeleton’s inability to contribute a greater proportion of assistance due to the excessive load on specific skeletal and muscular structures, resulting in wearer discomfort. Furthermore, the effectiveness of the EFOC method is evaluated and validated for assistance during both the stance and swing phases of single-leg movements. Finally, the proposed EFOC method is implemented on a hydraulic-driven lower limb exoskeleton robot to assist wearers in squatting, stepping, and jumping locomotion. The experimental results demonstrate that the proposed EFOC method can effectively achieve the desired assistance effect. Full article
(This article belongs to the Special Issue Rehabilitation Robots and Assistive Devices: A Special Issue in Honor of Prof. Dr. Rory A. Cooper)
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10 pages, 3290 KiB  
Article
Design of a Tripod LARMbot Arm
by Marco Ceccarelli, Steven Beaumont and Matteo Russo
Actuators 2024, 13(6), 211; https://doi.org/10.3390/act13060211 - 5 Jun 2024
Viewed by 449
Abstract
A new design for humanoid arms is presented based on a tripod mechanism that is actuated by linear servomotors. A specific prototype is built and tested, with the results of performance characterization verifying a possible implementation on the LARMbot humanoid. The design solves [...] Read more.
A new design for humanoid arms is presented based on a tripod mechanism that is actuated by linear servomotors. A specific prototype is built and tested, with the results of performance characterization verifying a possible implementation on the LARMbot humanoid. The design solves the main requirements in terms of a high payload ratio with respect to arm weight by using a tripod architecture with parallel manipulator behavior. The built prototype is assembled with commercial components to match the expectations for low-cost user-oriented features. The test results show satisfactory operation characteristics both in motion and force performance, which will ensure a future successful implementation in the LARMbot humanoid structure. Full article
(This article belongs to the Special Issue Advanced Robots: Design, Control and Application—2nd Edition)
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15 pages, 7346 KiB  
Article
Dynamic Modeling and Control of a 4-Wheel Narrow Tilting Vehicle
by Sunyeop Lee, Hyeonseok Cho and Kanghyun Nam
Actuators 2024, 13(6), 210; https://doi.org/10.3390/act13060210 - 4 Jun 2024
Viewed by 418
Abstract
The automotive industries currently face challenges such as emission limits, traffic congestion, and limited parking, which have prompted shifts in consumer preferences and modern passenger vehicle requirements towards compact vehicles. However, given the inherent limited width of compact vehicles, the potential risk of [...] Read more.
The automotive industries currently face challenges such as emission limits, traffic congestion, and limited parking, which have prompted shifts in consumer preferences and modern passenger vehicle requirements towards compact vehicles. However, given the inherent limited width of compact vehicles, the potential risk of vehicle rollover is greater than that of regular vehicles. This paper addresses the safety concerns associated with vehicle rollover, focusing on narrow tilting vehicles (NTVs). Quantifying stability involves numerical indicators such as the lateral load transfer ratio (LTR). Additionally, a unique approach is taken by applying ZMP (zero moment point), commonly used in the robotics field, as an indicator of vehicle stability. Effective roll control requires a detailed analysis of the vehicle’s characteristic model and the derivation of lateral and roll dynamics. The paper presents the detailed roll dynamics of an NTV with a MacPherson strut-type suspension. A stability-enhancing method is proposed using a cascade structure based on the internal robust position controller and outer roll stability controller, addressing challenges posed by disturbances. Experimental verification using Simscape Multibody and CarSim validates the dynamic model and controller’s effectiveness, ensuring the reliability of the proposed tilting control for NTVs in practical scenarios. Full article
(This article belongs to the Special Issue Modeling and Control for Chassis Devices in Electric Vehicles)
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15 pages, 6550 KiB  
Article
Light-Weighting and Comparative Simulation Analysis of the Forearm of Welding Robots
by Hongchen Pang, Zibin Sun, Jiezhen Hu and Fang Yang
Actuators 2024, 13(6), 209; https://doi.org/10.3390/act13060209 - 4 Jun 2024
Viewed by 234
Abstract
The light-weighting of a robotic arm is an important aspect of robot research. In the operation of existing welding robots, excessive vibrations in the welding actuators have been observed, which lead to reduced welding precision and work efficiency. The direct connection between the [...] Read more.
The light-weighting of a robotic arm is an important aspect of robot research. In the operation of existing welding robots, excessive vibrations in the welding actuators have been observed, which lead to reduced welding precision and work efficiency. The direct connection between the forearm and the welding actuator is a key component that affects vibrations. Based on this, a study on light-weighting the forearm is proposed. Using the theory of topology optimization with variable density structure, the structural dimensions, shapes, and geometric parameters of the forearm are optimized. The material removal methods of “hole cutting” and “local hollowing” are employed to reconstruct the forearm structure model. Static, modal, and transient simulations were performed on the forearm model pre-optimization and post-optimization. The optimization results show that the mass of the forearm is reduced by 19.8%. The static simulation comparative analysis shows that, under the same constraints and load conditions, the maximum total deformation of the optimized forearm is reduced by 3.6%, the maximum stress is reduced by 3.2%, and the maximum equivalent elastic strain is reduced by 5.7%. The optimized forearm structure is more reasonable and exhibits better mechanical performance. Modal simulation comparative analysis shows that the first and second natural frequencies of the optimized forearm are increased by 9.8% and 7.0%, respectively. Transient simulation comparative analysis demonstrates that, under the maximum operating condition, the vibration frequency and amplitude of the optimized welding robot forearm are reduced by 19.4% and 26.9%, respectively. The maximum amplitudes of the maximum equivalent stress curve and maximum equivalent elastic strain curve are reduced by 51.0% and 46.0%, respectively. This study provides a guarantee for reducing vibrations in welding actuators, improving welding precision, and enhancing the work efficiency of the welding robot. Full article
(This article belongs to the Section Actuators for Robotics)
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27 pages, 6977 KiB  
Article
A Novel Continuously Variable Transmission with Circumferentially Arranged Disks (CAD CVT)
by Muhammad Bilal, Qidan Zhu, Shafiq R. Qureshi, Ahsan Elahi, Muhammad Kashif Nadeem and Sartaj Khan
Actuators 2024, 13(6), 208; https://doi.org/10.3390/act13060208 - 3 Jun 2024
Viewed by 233
Abstract
This paper presents a novel Continuous Variable Transmission (CVT) design. CVT is highly beneficial for actuators with rotary output as it can improve the energy efficiency of the actuators by providing an optimum transmission ratio. This property of CVT is highly beneficial for [...] Read more.
This paper presents a novel Continuous Variable Transmission (CVT) design. CVT is highly beneficial for actuators with rotary output as it can improve the energy efficiency of the actuators by providing an optimum transmission ratio. This property of CVT is highly beneficial for fossil-fuel-based vehicles, electric vehicles, wind turbines, industrial robots, etc. With the exception of Spherical CVT and DH CVT, all known CVTs like push belt CVTs, toroidal CVTs, Milner CVTs, etc., require additional gear sets and clutches for direction reversal and neutral gear ratio. However, Spherical CVT and DH CVT have low torque capacity due to a single traction point constraint. Foregoing in view, a new CVT named CAD CVT has been developed. The paper presents the design conception, the operating principle, the transmission ratio, the torque capacity, frictional losses, and experimental verification of the basic functionality by manufacturing a Proof of Concept (PoC). The proposed CVT is the only CVT capable of independent direction reversal and high torque capacity as it can transmit torque through multiple traction points. The new CVT will significantly impact high-torque applications in different engineering applications, especially land transport consisting of heavy vehicles like trucks, buses, and trailers. Full article
(This article belongs to the Section Actuators for Land Transport)
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19 pages, 4692 KiB  
Article
Observer-Based Fault-Tolerant Control for Uncertain Robot Manipulators without Velocity Measurements
by Xuan-Toa Tran, Van-Cuong Nguyen, Phu-Nguyen Le and Hee-Jun Kang
Actuators 2024, 13(6), 207; https://doi.org/10.3390/act13060207 - 1 Jun 2024
Viewed by 313
Abstract
In recent years, robot manipulator arms have become increasingly prevalent and are playing pivotal roles across various industries. Their ability to replace human labor in arduous and hazardous tasks has positioned them as indispensable assets. Consequently, there has been a surge in research [...] Read more.
In recent years, robot manipulator arms have become increasingly prevalent and are playing pivotal roles across various industries. Their ability to replace human labor in arduous and hazardous tasks has positioned them as indispensable assets. Consequently, there has been a surge in research efforts aimed at enhancing their operational performance. The imperative to improve their efficiency and effectiveness has garnered significant attention within the research community. In this study, a novel fault-tolerant control (FTC) scheme for robot manipulators to handle the effects of the unknown input is proposed to aid robots in achieving good tracking performance. In the first step, an extended state observer (ESO) is constructed to approximate both velocities and the unknown input in the robot system. The observer offers estimation information with good accuracy and quick convergence. The estimated signals are then combined with computed torque control (CTC), which is a useful control technique for trajectory tracking of robot manipulator systems, to construct an active FTC to decrease the influences of the unknown input. The proposed algorithm does not require velocity measurement in the design process. In addition, with a novel design approach, the combination of controller and observer provides a novel control signal that delivers higher tracking performance compared to the traditional design approach. The global and asymptotic stability of the suggested technique is proved through the Lyapunov theory. Finally, simulations are implemented on a 2-degree-of-freedom (DOF) robot manipulator to validate the efficiency of the proposed controller–observer method. Full article
(This article belongs to the Section Control Systems)
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39 pages, 16682 KiB  
Article
Design and Analysis of the Mechanical Structure of a Robot System for Cabin Docking
by Ronghua Liu and Feng Pan
Actuators 2024, 13(6), 206; https://doi.org/10.3390/act13060206 - 30 May 2024
Viewed by 306
Abstract
Aiming at the disadvantages of traditional manual docking, such as low assembly efficiency and large positioning error, a six-DOF dual-arm robot system for module docking is designed. Firstly, according to the operation tasks of the cabin docking robot, its functional requirements and key [...] Read more.
Aiming at the disadvantages of traditional manual docking, such as low assembly efficiency and large positioning error, a six-DOF dual-arm robot system for module docking is designed. Firstly, according to the operation tasks of the cabin docking robot, its functional requirements and key indicators are determined, the overall scheme of the robot is designed, and the composition and working principle of the robot joints are introduced in detail. Secondly, a strength analysis of the core components of the docking robot is carried out by finite element analysis software to ensure its load capacity. Based on the kinematics model of the robot, the working space of the robot mechanism is simulated and analyzed. Finally, the experimental platform of the docking robot is built, and the working space, repeated positioning accuracy, and motion control accuracy of the docking robot mechanism are verified through experiments, which meet the design requirements. Full article
(This article belongs to the Special Issue Advanced Robots: Design, Control and Application—2nd Edition)
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16 pages, 1857 KiB  
Article
Robust Geometric Control for a Quadrotor UAV with Extended Kalman Filter Estimation
by Bo Lei, Bo Liu and Changhong Wang
Actuators 2024, 13(6), 205; https://doi.org/10.3390/act13060205 - 29 May 2024
Viewed by 323
Abstract
This study proposes a robust geometric controller tailored for quadrotor unmanned aerial vehicles (UAVs). The original geometric controller exhibits excellent performance in quadrotor UAV maneuvers. However, as a model-based nonlinear control method, it is sensitive to system model parameters. By integrating a novel [...] Read more.
This study proposes a robust geometric controller tailored for quadrotor unmanned aerial vehicles (UAVs). The original geometric controller exhibits excellent performance in quadrotor UAV maneuvers. However, as a model-based nonlinear control method, it is sensitive to system model parameters. By integrating a novel extended Kalman filter (EKF)-based estimator for real-time, online estimation of the quadrotor’s inertia parameters, the controller adeptly handles internal uncertainties and external perturbations during flight maneuvers. This approach significantly improves the robustness of the control system against model inaccuracies. Empirical evidence is provided through both simulation and extensive real-world flight tests, demonstrating the controller’s effectiveness and its practical applicability in dynamic environments. The results confirm that this integration substantially enhances system reliability and performance under varied operational conditions. Full article
(This article belongs to the Section Aircraft Actuators)
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18 pages, 8899 KiB  
Article
A Sparse Neural Network-Based Control Method for Saturated Nonlinear Affine Systems
by Jing Zhang, Baoqun Yin, Jianwen Huo, Hongliang Guo and Zhan Li
Actuators 2024, 13(6), 204; https://doi.org/10.3390/act13060204 - 29 May 2024
Viewed by 304
Abstract
Saturated nonlinear affine systems are widely encountered in many engineering fields. Currently, most control methods on saturated nonlinear affine systems are not specifically designed based on sparsity-based control methodologies, and they might require sparse identification at the beginning stage and applying tracking control [...] Read more.
Saturated nonlinear affine systems are widely encountered in many engineering fields. Currently, most control methods on saturated nonlinear affine systems are not specifically designed based on sparsity-based control methodologies, and they might require sparse identification at the beginning stage and applying tracking control afterwards. In this paper, a sparse neural network (SNN)-based control method from an lp-norm (1≤p<2) optimization perspective is proposed for saturated nonlinear affine systems by taking advantage of the nice properties of primal dual neural networks for optimization. In particular, when p=1, a new alternative controller based on SNN is derived, encountering computational difficulties distinct from those of another solution set in the basic dual neural network. The convergence properties of such SNN-based controllers are investigated and analyzed to find a control solution. Five illustrative examples further are shown to demonstrate the efficiency of the proposed SNN-based control method for tracking the desired references of saturated nonlinear affine systems. In the practical application scenario involving the UR5 robot control, the trajectory’s average errors are consistently confined to a minimal magnitude of 10−4 m. These findings substantiate the efficacy of the SNN-based control approach proposed for precise tracking control in saturated nonlinear affine systems. Full article
(This article belongs to the Special Issue From Theory to Practice: Incremental Nonlinear Control)
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17 pages, 4242 KiB  
Article
A Reliable and Efficient I-f Startup Method of Sensorless Ultra-High-Speed SPMSM for Fuel Cell Air Compressors
by Jilei Xing, Yao Xu, Junzhi Zhang, Yongshen Li and Xiongwei Jiang
Actuators 2024, 13(6), 203; https://doi.org/10.3390/act13060203 - 29 May 2024
Viewed by 344
Abstract
Extended back electromotive force (EEMF)-based position sensorless field-oriented control (FOC) is widely utilized for ultra-high-speed surface-mounted permanent magnet synchronous motors (UHS-SPMSMs) driven fuel cell air compressors in medium-high speed applications. Unfortunately, the estimated position is imprecise due to too small EEMF under low [...] Read more.
Extended back electromotive force (EEMF)-based position sensorless field-oriented control (FOC) is widely utilized for ultra-high-speed surface-mounted permanent magnet synchronous motors (UHS-SPMSMs) driven fuel cell air compressors in medium-high speed applications. Unfortunately, the estimated position is imprecise due to too small EEMF under low speed operation. Hence, current-to-frequency (I-f) control is more suitable for startup. Conventional I-f methods rarely achieve the tradeoff between startup acceleration and load capacity, and the transition to sensorless FOC is mostly realized in the constant-speed stage, which is unacceptable for UHS-SPMSM considering the critical requirement of startup time. In this article, a new closed-loop I-f control approach is proposed to achieve fast and efficient startup. The frequency of reference current vector is corrected automatically based on the active power and the real-time motor torque, which contributes to damping effect for startup reliability. Moreover, an amplitude compensator of reference current vector is designed based on the reactive power, ensuring the maximum torque per ampere operation and higher efficiency. Furthermore, the speed PI controller is enhanced by variable bandwidth design for smoother sensorless transition. These theoretical advantages are validated through experiments with a 550 V, 35 kW UHS-SPMSM. The experimental results demonstrated the enhanced startup performance compared with conventional I-f control. Full article
(This article belongs to the Special Issue Power Electronics and Actuators)
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22 pages, 8855 KiB  
Article
Passive and Active Training Control of an Omnidirectional Mobile Exoskeleton Robot for Lower Limb Rehabilitation
by Suyang Yu, Congcong Liu, Changlong Ye and Rongtian Fu
Actuators 2024, 13(6), 202; https://doi.org/10.3390/act13060202 - 25 May 2024
Viewed by 445
Abstract
As important auxiliary equipment, rehabilitation robots are widely used in rehabilitation treatment and daily life assistance. The rehabilitation robot proposed in this paper is mainly composed of an omnidirectional mobile platform module, a lower limb exoskeleton module, and a support module. According to [...] Read more.
As important auxiliary equipment, rehabilitation robots are widely used in rehabilitation treatment and daily life assistance. The rehabilitation robot proposed in this paper is mainly composed of an omnidirectional mobile platform module, a lower limb exoskeleton module, and a support module. According to the characteristics of the robot’s omnidirectional mobility and good stiffness, the overall kinematic model of the robot is established using the analytical method. Passive and active training control strategies for an omnidirectional mobile lower limb exoskeleton robot are proposed. The passive training mode facilitates the realization of the goal of walking guidance and assistance to the human lower limb. The active training mode can realize the cooperative movement between the robot and the human through the admittance controller and the tension sensor and enhance the active participation of the patient. In the simulation experiment, a set of optimal admittance parameters was obtained, and the parameters were substituted into the controller for the prototype experiment. The experimental results show that the admittance-controlled rehabilitation robot can perceive the patient’s motion intention and realize the two walking training modes. In summary, the passive and active training control strategies based on admittance control proposed in this paper achieve the expected purpose and effectively improve the patient’s active rehabilitation willingness and rehabilitation effect. Full article
(This article belongs to the Special Issue Intelligent Systems, Robots and Devices for Healthcare and Rehabilitation)
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17 pages, 8167 KiB  
Article
Ramp Start and Speed Control of Self-Driving Commercial Vehicles under Ramp and Vehicle Load Uncertainty
by Dequan Zeng, Huafu Fang, Yinquan Yu, Yiming Hu, Peizhi Zhang and Wei Luo
Actuators 2024, 13(6), 201; https://doi.org/10.3390/act13060201 - 24 May 2024
Viewed by 379
Abstract
In order to improve the performance of self-driving commercial vehicles for half-hill starting, a ramp control strategy based on the back-slip speed corresponding to the parking moment is proposed. Firstly, the longitudinal dynamics model of the vehicle is established, the force of the [...] Read more.
In order to improve the performance of self-driving commercial vehicles for half-hill starting, a ramp control strategy based on the back-slip speed corresponding to the parking moment is proposed. Firstly, the longitudinal dynamics model of the vehicle is established, the force of the vehicle on the ramp is analyzed, and the rear slip speed of the vehicle is matched with the parking moment, and finally the target speed is tracked based on the sliding-mode controller, and in order to validate the validity of the method, two comparative algorithms of the pure PI controller and the proportional gain controller based on the back-sliding speed corresponding to the resting moment are designed for comparative experiments, and the data results show that the control strategy based on the resting moment corresponding to the backsliding speed of the sliding mode ramp start control strategy can stably complete the ramp start under different weights and different slopes, and greatly reduce the backsliding distance of the vehicle. Full article
(This article belongs to the Special Issue Advanced Actuation and Control Technologies for Vehicle Driving Systems)
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