Actuators

25 pages, 4148 KiB

Open AccessArticle

A Disturbance Sliding Mode Observer Designed for Enhancing the LQR Current-Control Scheme of a Permanent Magnet Synchronous Motor

by Zhidong Zhang, Gongliu Yang, Jing Fan, Tao Li and Qingzhong Cai

Actuators 2024, 13(8), 283; https://doi.org/10.3390/act13080283 (registering DOI) - 26 Jul 2024

Abstract

This paper introduces a current control method for permanent magnet synchronous motors (PMSMs) using a disturbance sliding mode observer (DSMO) in conjunction with a linear quadratic regulator (LQR). This approach enhances control performance, streamlines the tuning of controller parameters, and offers robust optimal [...] Read more.

This paper introduces a current control method for permanent magnet synchronous motors (PMSMs) using a disturbance sliding mode observer (DSMO) in conjunction with a linear quadratic regulator (LQR). This approach enhances control performance, streamlines the tuning of controller parameters, and offers robust optimal control that is resistant to system disturbances. The LQR controller based on state feedback is advantageous for its simplicity in parameter adjustment and achieving an optimal control effect easily under specific performance indicators. It is suitable for the optimal control of strong linear systems that can be accurately modeled. However, most practical systems are difficult to model accurately, and the time-varying system parameters and existing nonlinearity limit the engineering application of LQR. In the PMSM current control loop, there is strong nonlinear disturbance manifesting as the nonlinearity of its dynamic model. Additionally, substantial noise and variations in system parameters within actual motor circuits hinder the linear quadratic regulator from attaining optimal performance. A disturbance sliding mode observer is proposed to enhance the LQR controller, enabling superior performance in nonlinear current loop control. Simulation and actual hardware experiments were conducted to verify the performance and robustness of the control scheme proposed in this paper. Compared with the widely used PI controller in engineering and sliding mode control (SMC) specialising in disturbance rejection, it offers the advantage of straightforward parameter tuning and can swiftly achieve the robust and optimal control performance that engineers prioritize. Full article

(This article belongs to the Special Issue Recent Developments in Precision Actuation Technologies)

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15 pages, 9253 KiB

Open AccessArticle

Double Air Chambers Pneumatic Artificial Muscle and Non-Hysteresis Position Control

by Naoki Saito, Toshiyuki Satoh and Norihiko Saga

Actuators 2024, 13(8), 282; https://doi.org/10.3390/act13080282 (registering DOI) - 26 Jul 2024

Abstract

In this paper, we propose a double air chambers artificial muscle to eliminate the hysteresis in the extension and contraction movement of pneumatic artificial muscles. In this paper, the basic structure of the double air chambers artificial muscle is a rubberless artificial muscle [...] Read more.

In this paper, we propose a double air chambers artificial muscle to eliminate the hysteresis in the extension and contraction movement of pneumatic artificial muscles. In this paper, the basic structure of the double air chambers artificial muscle is a rubberless artificial muscle with a particularly large hysteresis loop. The double air chambers artificial muscle aims to eliminate hysteresis by directly pressurizing the inside and outside of the air chamber and actively deforming the air chamber. The hysteresis is reduced by the pressure outside of the air chamber (external pressure). Since the appropriate external pressure varies depending on the contraction force and amount of contraction, we proposed a method to regulate the appropriate external pressure by feedback control. The experimental results show that hysteresis was eliminated in the static characteristics. It was also found that the output gain decreased, and the phase lag increased as the target frequency increased. The output gain did not change with increasing load. The phase lag tended to improve with the PID controller compared to the PI controller. These results suggest that the combination of double air chambers artificial muscle and external pressure-regulated feedback control can achieve non-hysteresis position control, and it is useful as an actuator in mechatronic systems. Full article

(This article belongs to the Special Issue Advanced Technologies in Soft Pneumatic Actuators)

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20 pages, 14538 KiB

Open AccessArticle

Design and Implementation of Bulk Feeders Using Voice Coil Motors

by Yu-Ting Yang, Wen-Tan Wang and Ching-Chang Wong

Actuators 2024, 13(8), 281; https://doi.org/10.3390/act13080281 (registering DOI) - 26 Jul 2024

Abstract

Bulk feeders that can automatically feed materials are one of the most commonly used vibration devices in the electronics industry. This study uses voice coil motors to design and implement a dual-axis bulk feeder and a quad-axis bulk feeder, allowing them to handle [...] Read more.

Bulk feeders that can automatically feed materials are one of the most commonly used vibration devices in the electronics industry. This study uses voice coil motors to design and implement a dual-axis bulk feeder and a quad-axis bulk feeder, allowing them to handle many kinds of materials. The implemented feeders can improve some of the problems in traditional bulk feeders, such as only one direction of movement, can only handle one kind of material, the contact time between the material and the platform is too long, and the feeder is not suitable to process materials with particular shapes. Two or four voice coil motors are placed under the platform of the implemented feeder. The vibration of the platform is controlled by the up-and-down movements of the voice coil motors, so that the bulk materials on the platform can be moved to the desired direction according to the feeding requirements. This study proposes a control method to control voice coil motors. For example, using different combinations of up-and-down movements of these four voice coil motors, the quad-axis voice coil feeder can move the material in eight horizontal directions, such as up, down, right, left, up right, up left, down right, and down left, as well as vertically flip. Since the frequency and amplitude of each vibration of the voice coil motor can be easily and instantly adjusted through the program, the implemented feeder can handle other types of materials without modifying the hardware of the device. Finally, some experimental results illustrate that the implemented dual-axis and quad-axis voice coil feeders can indeed effectively handle various bulk materials. Full article

(This article belongs to the Special Issue Industrial and Biomechanical Applications of Actuators and Robots and Eco-Sustainability)

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25 pages, 8268 KiB

Open AccessArticle

Simulation Training System for Parafoil Motion Controller Based on Actor–Critic RL Approach

by Xi He, Jingnan Liu, Jing Zhao, Ronghua Xu, Qi Liu, Jincheng Wan and Gang Yu

Actuators 2024, 13(8), 280; https://doi.org/10.3390/act13080280 - 25 Jul 2024

Viewed by 134

Abstract

The unique ram air aerodynamic shape and control rope pulling course of the parafoil system make it difficult to realize its precise control. At present, the commonly used control methods of the parafoil system include proportional–integral–derivative (PID) control, model predictive control, and adaptive [...] Read more.

The unique ram air aerodynamic shape and control rope pulling course of the parafoil system make it difficult to realize its precise control. At present, the commonly used control methods of the parafoil system include proportional–integral–derivative (PID) control, model predictive control, and adaptive control. The control precision of PID control and model predictive control is low, while the adaptive control has the problems of complexity and high cost. This study proposes a new method to improve the control precision of the parafoil system by establishing a parafoil motion simulation training system that trains the neural network controllers based on actor–critic reinforcement learning (RL). Simulation results verify the feasibility of the proposed parafoil motion-control-simulation training system. Furthermore, the test results of the real flight experiment based on the motion controller trained by the proximal policy optimization (PPO) algorithm are presented, which are close to the simulation results. Full article

(This article belongs to the Special Issue Advances in Dynamics and Motion Control of Unmanned Aerial/Underwater/Ground Vehicles)

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26 pages, 8740 KiB

Open AccessArticle

Optimal Control-Based Algorithm Design and Application for Trajectory Tracking of a Mobile Robot with Four Independently Steered and Four Independently Actuated Wheels

by Branimir Ćaran, Vladimir Milić, Marko Švaco and Bojan Jerbić

Actuators 2024, 13(8), 279; https://doi.org/10.3390/act13080279 - 25 Jul 2024

Viewed by 191

Abstract

This paper deals with the synthesis and implementation of a controller for asymptotic tracking of the desired trajectory of a mobile robot. The mobile robot used for the experimental validation has eight motors with an inner control loop. Four steering actuators are controlled [...] Read more.

This paper deals with the synthesis and implementation of a controller for asymptotic tracking of the desired trajectory of a mobile robot. The mobile robot used for the experimental validation has eight motors with an inner control loop. Four steering actuators are controlled using position controllers and four driving actuators are controlled using velocity controllers. A complex robot kinematic model is converted into a control-oriented linear time-varying system, which is then used to design a time-varying control law that minimizes the quadratic optimality criterion. In contrast to conventional methodologies for solving the corresponding Riccati differential equations, a computational approach that explicitly determines the time-varying controller matrix by employing recurrent matrix computations is proposed. Mobile robot control inputs (linear velocity, steering angles and steering velocities) are forwarded to the steering and driving actuators with properly tuned position and velocity controllers using an inverse kinematic model of the mobile robot. The obtained control law is evaluated on an experimental set-up of a real mobile robot system. The controller is implemented using the Robot Operating System. Full article

(This article belongs to the Special Issue Actuators in 2024)

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12 pages, 443 KiB

Open AccessArticle

Two-Stage Control Strategy Based on Motion Planning for Planar Prismatic–Rotational Underactuated Robot

by Dawei Li, Ziang Wei and Zixin Huang

Actuators 2024, 13(8), 278; https://doi.org/10.3390/act13080278 - 25 Jul 2024

Viewed by 144

Abstract

Intelligent robots are often used to explore various areas instead of humans. However, when the driving joint is damaged, the actuated robot degenerates to an underactuated robot, and the traditional control method is not suitable for the underactuated robot. In this work, a [...] Read more.

Intelligent robots are often used to explore various areas instead of humans. However, when the driving joint is damaged, the actuated robot degenerates to an underactuated robot, and the traditional control method is not suitable for the underactuated robot. In this work, a two-stage control approach for a planar prismatic–rotational (PR) underactuated robot is introduced. Firstly, we establish the dynamic model and describe the underactuated constraint between an underactuated rotational joint and active prismatic joint. Secondly, the trajectory with multiple parameters is planned to ensure that the two joints reach the target position. Based on underactuated constraints and the evaluation function, the differential evolution algorithm (DEA) is used to optimize these parameters. After that, in stage 1, we design the controller to move the active prismatic joint to the desired position. Meanwhile, the underactuated rotational joint is rotating freely. In stage 2, we design the controller for the active prismatic joint to track the planned trajectory. By means of this strategy, both joints reach their target locations simultaneously. The final simulation result demonstrates that this strategy is effective. Full article

(This article belongs to the Special Issue Dynamics and Control of Underactuated Systems)

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20 pages, 6319 KiB

Open AccessArticle

The Actuating Characteristics of Magnetorheological Fluids Subjected to Particle Sedimentation and Temperature Variation

by Elliza Tri Maharani, Dong-Hoon Lee, Young-Jun Kim, Jong-Seok Oh and Seung-Bok Choi

Actuators 2024, 13(8), 277; https://doi.org/10.3390/act13080277 - 24 Jul 2024

Viewed by 244

Abstract

Magnetorheological (MR) fluids are known for their controllable characteristics under the influence of magnetic fields and, hence, widely used as semi-active actuators for vibration control. Regardless of advantages such as fast response time and reversible property, MR fluids inevitably experience sedimentation caused by [...] Read more.

Magnetorheological (MR) fluids are known for their controllable characteristics under the influence of magnetic fields and, hence, widely used as semi-active actuators for vibration control. Regardless of advantages such as fast response time and reversible property, MR fluids inevitably experience sedimentation caused by significant density mismatches between magnetic particles and carrier liquids. Moreover, the effect of the temperature on actuating characteristics is also one of the problems to be resolved for practical implementation. This study experimentally investigates the sedimentation behavior under various temperatures ranging from 25 to 70 °C using a multiguide-arm magnetic device that generates a uniform magnetic flux density across MR fluids. The sedimentation stability is then observed after 168 h at current inputs of 0, 1, and 2 A, respectively. Subsequently, the field-dependent rheological properties of MR fluids are evaluated using a rheometer and discussed, showing actuating capability, which depends on the viscosity, shear stress, and yield stress before (initial state) and after the sedimentation (sedimentation state). The field-dependent yield stresses, which directly represent the actuating force of the semi-active actuator, are specifically evaluated. Under the on-state condition (2 A) at a temperature of 70 °C, the yield stress decreased from 2.747 kPa (initial state) to 2.352 kPa (sedimentation state). By using this yield stress, the field-dependent damping force was evaluated, showing a decrement from 1672 N (initial state) to 1623 N (sedimentation state) at a velocity of 0.8 m/s. It is shown that the temperature causes the reduction of the actuating properties after the long-term operation. The insightful findings achieved in this work will provide useful information for the evaluation of actuating characteristics of smart MR fluids and the design of MR application systems subjected to particle sedimentation and temperature variation. Full article

(This article belongs to the Special Issue Magnetorheological Actuators and Dampers)

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15 pages, 4708 KiB

Open AccessArticle

Minitype Arrays of Acoustically Actuated Magnetoelectric Antennas for Magnetic Induction Communication

by Shiyu Wang, Gaoqi Dou and Guangming Song

Actuators 2024, 13(8), 276; https://doi.org/10.3390/act13080276 - 23 Jul 2024

Viewed by 203

Abstract

The magnetoelectric (ME) antennas rely on the mechanical movement of magnetic dipoles, making it possible to break the constraints on physical dimensions decided by the wavelength of the electromagnetic wavelength. The ME antennas achieve super-low frequency (SLF) communications with a smaller size to [...] Read more.

The magnetoelectric (ME) antennas rely on the mechanical movement of magnetic dipoles, making it possible to break the constraints on physical dimensions decided by the wavelength of the electromagnetic wavelength. The ME antennas achieve super-low frequency (SLF) communications with a smaller size to provide a novel solution for long-range, underwater, and underground communications; navigation over the horizon; and geological exploring. As a result, further theoretical research and optimization of ME antennas have been an open challenge for decades. Here, we report on minitype arrays of acoustically actuated ME antenna and their more rigorous equivalent circuits. These arrays of ME antenna adjust amplitude-frequency response through the mechanical regulation method. The mechanical parameters of ME antennas in the arrays result in regulating amplitude-frequency response, such as working frequency, fractional bandwidth, and intensity of magnetic induction. Our work provides a more accurate theoretical model and diverse array form over state-of-the-art ME antenna arrays. The frequency, fractional bandwidth, and magnetic induction strength of the ME antenna arrays were achieved to be adjustable in the ranges of 84 to 181 Hz, 3.9% to 8.3%, and two to four times, respectively. In addition, we have calculated the attenuation characteristics of ME antennas and their minitype arrays in seawater. The results show that the ME antenna array described in this manuscript is able to enhance the radiation intensity and information-loading capability, which has a positive potential for application in SLF communication systems. Full article

(This article belongs to the Special Issue Advanced Technologies on the Control Method of Electromagnetic Actuator)

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17 pages, 7956 KiB

Open AccessArticle

A High Torque Density Dual-Stator Flux-Reversal-Machine with Multiple Poles Halbach Excitation on Outer Stator

by Siwei Tang, Yuanying Xu, Chao He and Jiquan Yang

Actuators 2024, 13(8), 275; https://doi.org/10.3390/act13080275 - 23 Jul 2024

Viewed by 229

Abstract

This paper proposes a high torque density dual-stator flux-reversal-machine with multiple poles Halbach excitation (MPHE-DSFRM), which uses two pole pairs’ numbers (PPNs) of PM excitation on one outer stator tooth, and one PPN of PM excitation on one inner stator tooth. The introduction [...] Read more.

This paper proposes a high torque density dual-stator flux-reversal-machine with multiple poles Halbach excitation (MPHE-DSFRM), which uses two pole pairs’ numbers (PPNs) of PM excitation on one outer stator tooth, and one PPN of PM excitation on one inner stator tooth. The introduction of different PPNs of PM excitation on the outer and the inner stators can optimize magnetic circuit and airgap flux density. A Halbach array is formed by inserting three pieces of circumferentially magnetized PMs into four pieces of radially magnetized permanent magnets (PMs) on the outer stator, which aims to further enhance torque density, and reduce torque ripple. Based on the flux modulation effect, the analytical modeling of the proposed MPHE-DSFRM is established, together with the evolution process, and the working principle is presented. Then, the key design parameters of MPHE-DSFRM are optimized to achieve high torque density and low torque ripple for high torque quality. Three representative DSFRMs and a conventional FRM are designed and analyzed, and they share the same design key parameters, including PM usage, outer radius of the outer stator, and active airgap length. The electromagnetic performances, including airgap flux density, back electromotive force (back-EMF), and torque characteristics, are analyzed and compared by finite element analysis (FEA). The calculated results show that the proposed MPHE-DSFRM can provide high torque density and high PM utilization. Full article

(This article belongs to the Section High Torque/Power Density Actuators)

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Actuators, Volume 13, Issue 8 (August 2024) – 9 articles

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