Actuators

18 pages, 3552 KiB

Open AccessArticle

Experimental Confirmation of a Controllable Transmission/Braking Element Consisting of a Functional Elastomer Pasted on a Winding Surface

by Ken’ichi Koyanagi, Yasuhiro Kakinuma, Hidenobu Anzai, Koji Sakurai and Toru Oshima

Actuators 2022, 11(4), 114; https://doi.org/10.3390/act11040114 - 18 Apr 2022

Viewed by 1933

Abstract

Electoadhesive (EA) gel can be applied to various mechatronics devices because it provides more degrees of freedom in mechanical design than other functional materials. While case studies have revealed much about these devices, the knowledge attained is still not integrated. We assembled new [...] Read more.

Electoadhesive (EA) gel can be applied to various mechatronics devices because it provides more degrees of freedom in mechanical design than other functional materials. While case studies have revealed much about these devices, the knowledge attained is still not integrated. We assembled new structured and controllable transmission and braking elements by fixing EA gel on plain and/or winding surfaces. This paper summarizes the characteristics of these devices from experimental findings on the initial pressure on the EA gel surface. The results showed that it is important for the initial pressure to be stable at approximately 0.5–1 kPa. Full article

(This article belongs to the Special Issue Smart Materials for Smart Actuators and Semi-active Components)

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18 pages, 2652 KiB

Open AccessArticle

Heterogeneous Multi-Agent-Based Fault Diagnosis Scheme for Actuation System

by Yuyan Cao, Ting Li, Yang Li and Xinmin Wang

Actuators 2022, 11(4), 113; https://doi.org/10.3390/act11040113 - 18 Apr 2022

Cited by 2 | Viewed by 1861

Abstract

In this paper, a fault diagnosis method of a heterogeneous multi-agent is proposed that realizes the rapid and accurate fault diagnosis of a redundant multi-type actuation system of large aircraft. Firstly, the multi-agent model of a large aircraft actuation system is established, the [...] Read more.

In this paper, a fault diagnosis method of a heterogeneous multi-agent is proposed that realizes the rapid and accurate fault diagnosis of a redundant multi-type actuation system of large aircraft. Firstly, the multi-agent model of a large aircraft actuation system is established, the composition of the actuation system and the relationship between each multi-agent are clarified and three different types of actuator mathematical models are established. Secondly, a fault detection and isolation (FDI) model is established and transformed into an optimization problem according to different performance index requirements. Aiming at the optimization problem, combined with the principle of linear matrix inequality (LMI), the fault diagnosis algorithm of a heterogeneous multi-agent system is designed. Moreover, the threshold judgment method based on the error signal is presented. Finally, the three actuator models of the aileron actuation system of large aircraft are combined to complete the fault diagnosis of a heterogeneous multi-agent system under the given model interference and model fault. The obtained results demonstrate and validate that the proposed method can accurately and effectively diagnose the faults of the actuator and its associated actuators. Full article

(This article belongs to the Section Aircraft Actuators)

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18 pages, 3375 KiB

Open AccessArticle

Experimental Characterization of a Stick-Slip Driving Micro Conveyance Device Consisting of Digital Actuators

by Pengfei Huyan, Yulin Huang, Pengchao Li, Ximing Cui, Laurent Petit and Christine Prelle

Actuators 2022, 11(4), 112; https://doi.org/10.3390/act11040112 - 16 Apr 2022

Cited by 2 | Viewed by 2197

Abstract

Micro conveyance devices are important elements in high precision positioning systems, which play vital roles in many scientific and industrial fields and are widely needed in many applications. This work presents the modeling and experimental validation of a pre-designed and fabricated micro conveyance [...] Read more.

Micro conveyance devices are important elements in high precision positioning systems, which play vital roles in many scientific and industrial fields and are widely needed in many applications. This work presents the modeling and experimental validation of a pre-designed and fabricated micro conveyance device. This micro conveyance device consists of eight elementary electromagnetic digital actuators and can realize a conveyance application based on a stick-slip driving principle. A dynamic model based on the prototype device was established for stick-slip displacement simulation. Four sub-models of the dynamic model regarding the calculation of actuation force and friction force within the device were built and integrated. Experiments focusing on the conveyance application were carried out to test the performance of the prototype device. It has been observed that the simulated results obtained using the dynamic model were in good agreement with the experiment results. The proposed device suggests an alternative to the micro conveyance system. Full article

(This article belongs to the Section Precision Actuators)

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26 pages, 15979 KiB

Open AccessArticle

An Inverse Dynamics-Based Control Approach for Compliant Control of Pneumatic Artificial Muscles

by Cabbar Veysel Baysal

Actuators 2022, 11(4), 111; https://doi.org/10.3390/act11040111 - 16 Apr 2022

Cited by 4 | Viewed by 2448

Abstract

Rehabilitation is an area of robotics in which human–robot collaboration occurs, requiring adaptation and compliance. Pneumatic artificial muscles (PAM) are soft actuators that have built-in compliance making them usable for rehabilitation robots. Conversely, compliance arises from nonlinear characteristics and generates obstructions in modeling [...] Read more.

Rehabilitation is an area of robotics in which human–robot collaboration occurs, requiring adaptation and compliance. Pneumatic artificial muscles (PAM) are soft actuators that have built-in compliance making them usable for rehabilitation robots. Conversely, compliance arises from nonlinear characteristics and generates obstructions in modeling and controlling actions. It is a critical issue limiting the use of PAM. In this work, multi-input single-output (MISO) inverse modeling and inverse dynamics model learning approaches are combined to obtain a novel nonlinear adaptive control scheme for single PAM-actuated 1-DoF rehabilitation devices, for instance, continuous passive motion (CPM) devices. The objective of the proposed system is to bring an alternative solution to the compliant operation of PAM while performing exercise trajectories, to satisfy requirements such as larger range of motion (ROM) and adaptability to external load impedance variations. The control system combines the operation of a nonlinear autoregressive network with exogenous inputs (NARX)-based inverse dynamics estimator used as a global range controller and cascade PIDs for local position and pressure loops. Implementation results demonstrated the efficacy of the introduced method in terms of compliant operation for dynamic external load variations as well as a stable operation in case of impulsive disturbances. To summarize, a simple but efficient method is illustrated to facilitate the common use of PAM. Full article

(This article belongs to the Special Issue Pneumatic Muscle Actuators)

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15 pages, 5706 KiB

Open AccessArticle

Design of Longitudinal-Bending Coupled Horn of a Giant Magnetostriction Transducer

by Pengyang Li, Yunshuai Chen, Wei Li, Jian Sun, Jian Li and Kai Wang

Actuators 2022, 11(4), 110; https://doi.org/10.3390/act11040110 - 16 Apr 2022

Cited by 3 | Viewed by 2099

Abstract

This article presents a design method of Longitudinal-Bending Coupled Horn (L-BCH) of a giant magnetostrictive transducer utilized in spinning ultrasonic machining. The structural parameters are initially determined by the design theory of the horn and thick disc. Then, the effect of the structural [...] Read more.

This article presents a design method of Longitudinal-Bending Coupled Horn (L-BCH) of a giant magnetostrictive transducer utilized in spinning ultrasonic machining. The structural parameters are initially determined by the design theory of the horn and thick disc. Then, the effect of the structural parameters of the rotating wheel on the vibration characteristics of the L-BCH are explored by the model and harmonic response analysis through the finite element method. Through continuous modification of the geometrical parameters of the rotary wheel, the L-BCH meeting the requirements of a giant magnetostrictive transducer is designed. Finally, the frequency and amplitude measurements are performed on the prototype by the impedance analyzer and the laser vibrometer. The finite element analysis and experimental results show that: the large diameter, small diameter, thickness, and fillet radius of the rotating wheel have different impacts on the dynamic characteristics of the L-BCH. Among them, the thickness of the rotary wheel has the most significant influence on the natural frequency and amplitude. In addition, the rotating wheel has a pitch circle when the longitudinal-bending coupled vibration occurs, and the structure itself also has the characteristic of amplifying amplitude. Full article

(This article belongs to the Topic Advances in Mobile Robotics Navigation)

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22 pages, 3206 KiB

Open AccessArticle

Local Path Planning of the Autonomous Vehicle Based on Adaptive Improved RRT Algorithm in Certain Lane Environments

by Xiao Zhang, Tong Zhu, Yu Xu, Haoxue Liu and Fei Liu

Actuators 2022, 11(4), 109; https://doi.org/10.3390/act11040109 - 15 Apr 2022

Cited by 8 | Viewed by 2693

Abstract

Given that the rapidly exploring random tree algorithm (RRT) and its variants cannot efficiently solve problems of path planning of autonomous vehicles, this paper proposes a new, adaptive improved RRT algorithm. Firstly, an adaptive directional sampling strategy is introduced to avoid excessive search [...] Read more.

Given that the rapidly exploring random tree algorithm (RRT) and its variants cannot efficiently solve problems of path planning of autonomous vehicles, this paper proposes a new, adaptive improved RRT algorithm. Firstly, an adaptive directional sampling strategy is introduced to avoid excessive search by reducing the randomness of sampling points. Secondly, a reasonable node selection strategy is used to improve the smoothness of the path by utilizing a comprehensive criterion that combines angle and distance. Thirdly, an adaptive node expansion strategy is utilized to avoid invalid expansion and make the generated path more reasonable. Finally, the expanded ellipse is used to realize vehicle obstacle avoidance in advance, and the post-processing strategy removes redundant line segments of the initial path to improve its quality. The simulation results show that the quality of the planned path is significantly improved. This path followed successfully has good trajectory stability, which shows the proposed algorithm’s effectiveness and practicability in autonomous vehicles’ local path planning. Full article

(This article belongs to the Special Issue Advancing Actuators-Based Land Transport Systems: State of the Art and New Technologies)

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20 pages, 8401 KiB

Open AccessArticle

Analysis of Magnetic Field Characteristics of a Giant Magnetostrictive Actuator with a Semi-Closed Magnetic Circuit

by Zhaoqi Zhou, Zhongbo He, Guangming Xue, Jingtao Zhou, Ce Rong and Guoping Liu

Actuators 2022, 11(4), 108; https://doi.org/10.3390/act11040108 - 15 Apr 2022

Cited by 2 | Viewed by 2005

Abstract

The internal magnetic field characteristics of giant magnetostrictive actuators have an important influence on their output performance. Aiming at the deficiency of current scholars’ research, based on the electromagnetic theory and finite element method, this paper analyzes the magnetic field intensity on a [...] Read more.

The internal magnetic field characteristics of giant magnetostrictive actuators have an important influence on their output performance. Aiming at the deficiency of current scholars’ research, based on the electromagnetic theory and finite element method, this paper analyzes the magnetic field intensity on a giant magnetostrictive cylinder by using COMSOL Multiphysics software. Considering the inhomogeneity of magnetic field intensity along the radial direction of giant magnetostrictive cylinders, a new averaging method is introduced to calculate the magnetic field intensity in the axial section of the cylinder. The influence of the magnetic permeability of the displacement conversion mechanism (shell) and the size of the air gap inside the device on the magnetic field intensity of the giant magnetostrictive cylinder are analyzed. The prototype of the actuator is manufactured, and the correctness and accuracy of the simulation data are verified by experiments. In order to make the magnetic field on the cylinder strong and uniform, the displacement conversion mechanism and the shell should be made of low permeability and high permeability materials, respectively, and the air gap size should be reduced as much as possible under the condition of meeting the size requirement of the actuator pre-tightening force applying device. Full article

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18 pages, 5780 KiB

Open AccessArticle

A Soft Self-Stable Actuator and Its Energy-Efficient Grasping

by Ji Luo, Pei Jiang, Xiaobin Li, Long Bai, Fuqiang Liu and Rui Chen

Actuators 2022, 11(4), 107; https://doi.org/10.3390/act11040107 - 07 Apr 2022

Cited by 2 | Viewed by 2569

Abstract

Due to high compliance and adaptiveness, soft robots show more advantages than traditional rigid robots in grasping irregularly shaped or fragile objects. Moreover, soft robots attract increasing attention as more and more robots are adopted in unstructured or human–robot interaction environments. However, during [...] Read more.

Due to high compliance and adaptiveness, soft robots show more advantages than traditional rigid robots in grasping irregularly shaped or fragile objects. Moreover, soft robots attract increasing attention as more and more robots are adopted in unstructured or human–robot interaction environments. However, during the grasping process, most soft robots need constant input stimuli to maintain the grasping configurations, which directly induces low energy efficiency. This article demonstrates the self-stable property of the dual-chamber structure, which can maintain bending deformation without input stimuli based on the differential pressure of the two chambers. Based on the self-stable property, a soft self-stable actuator (SSSA) driven by the tendon is proposed, and it can maintain the bending deformation without energy consumption, which can improve the energy efficiency of the actuator significantly. The self-stability of the actuator during the restoring period is analyzed, and the energy consumption model of the actuator is developed. Finally, the experiments are conducted to verify the validity of the models. The results show the actuator can achieve self-stability without any energy input, and the energy consumption can be reduced by about 45%. Hence, the proposed actuator can be adopted in applications where energy efficiency is sensitive. Full article

(This article belongs to the Section Actuators for Robotics)

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12 pages, 1996 KiB

Open AccessArticle

Electroelastic Coupled-Wave Scattering and Dynamic Stress Concentration of Triangular Defect Piezoceramics

by Jiang Lin, Huawei Ji, Chuanping Zhou, Jiawei Fan, Xiao Han, Junqi Bao, Yongping Gong, Jing Ni and Weihua Zhou

Actuators 2022, 11(4), 106; https://doi.org/10.3390/act11040106 - 07 Apr 2022

Cited by 1 | Viewed by 2018

Abstract

In this paper, a method to calculate the dynamic stress concentration around the triangular defect of piezoelectric material under electroelastic coupling is studied and applied to the promising barium calcium zirconate titanate. Firstly, the electroelastic governing equation is decomposed by decoupling technique, and [...] Read more.

In this paper, a method to calculate the dynamic stress concentration around the triangular defect of piezoelectric material under electroelastic coupling is studied and applied to the promising barium calcium zirconate titanate. Firstly, the electroelastic governing equation is decomposed by decoupling technique, and the analytical solutions of elastic wave field and electric field are obtained by wave function expansion method. Then, the conformal transformation is used to simplify the triangle boundary into a circular boundary, and the corresponding modal coefficients are determined according to the simplified boundary conditions. Finally, the analytical solution of the dynamic stress concentration factor can be obtained according to the constitutive equation. Substitute the relevant material parameters of (Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃ and set different temperatures, Ce doping amount, and incident wave number for numerical simulation. The numerical results show that the incident wave number, piezoelectric properties, and the shape parameters and deflection angle of the triangular defect have a great influence on the dynamic stress around the defect, and some meaningful laws are summarized through analysis. Full article

(This article belongs to the Special Issue Piezoelectric Actuators and Transducers: Materials, Design, Control and Applications)

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24 pages, 6395 KiB

Open AccessArticle

An Improved Proximal Policy Optimization Method for Low-Level Control of a Quadrotor

by Wentao Xue, Hangxing Wu, Hui Ye and Shuyi Shao

Actuators 2022, 11(4), 105; https://doi.org/10.3390/act11040105 - 06 Apr 2022

Cited by 3 | Viewed by 3088

Abstract

In this paper, a novel deep reinforcement learning algorithm based on Proximal Policy Optimization (PPO) is proposed to achieve the fixed point flight control of a quadrotor. The attitude and position information of the quadrotor is directly mapped to the PWM signals of [...] Read more.

In this paper, a novel deep reinforcement learning algorithm based on Proximal Policy Optimization (PPO) is proposed to achieve the fixed point flight control of a quadrotor. The attitude and position information of the quadrotor is directly mapped to the PWM signals of the four rotors through neural network control. To constrain the size of policy updates, a PPO algorithm based on Monte Carlo approximations is proposed to achieve the optimal penalty coefficient. A policy optimization method with a penalized point probability distance can provide the diversity of policy by performing each policy update. The new proxy objective function is introduced into the actor–critic network, which solves the problem of PPO falling into local optimization. Moreover, a compound reward function is presented to accelerate the gradient algorithm along the policy update direction by analyzing various states that the quadrotor may encounter in the flight, which improves the learning efficiency of the network. The simulation tests the generalization ability of the offline policy by changing the wing length and payload of the quadrotor. Compared with the PPO method, the proposed method has higher learning efficiency and better robustness. Full article

(This article belongs to the Special Issue Intelligent Control of Flexible Manipulator Systems and Robotics)

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24 pages, 7792 KiB

Open AccessArticle

Control Allocation Design for Torpedo-Like Underwater Vehicles with Multiple Actuators

by Yung-Yue Chen, Chun-Yen Lee, Ya-Xuan Huang and Tsung-Tso Yu

Actuators 2022, 11(4), 104; https://doi.org/10.3390/act11040104 - 29 Mar 2022

Cited by 4 | Viewed by 3150

Abstract

For solving the transformation problem between the desired nonlinear control laws and installed actuators’ input commands of torpedo-like underwater vehicles, one closed-form control allocation method is proposed in this article. The goal of this study is to optimally distribute the desired nonlinear control [...] Read more.

For solving the transformation problem between the desired nonlinear control laws and installed actuators’ input commands of torpedo-like underwater vehicles, one closed-form control allocation method is proposed in this article. The goal of this study is to optimally distribute the desired nonlinear control law to each single actuator installed on the torpedo-like underwater vehicle. The first step of this proposed control allocation method is to arrange the required types, numbers, and positions of the installed actuators and then build up the thrust configuration matrix for the developed torpedo-like underwater vehicle. In this step, the desired nonlinear control law can be optimally distributed to output commands of installed actuators based on the optimization method. Next, through collecting the input and output data of each installed actuator by practical experiments, the mathematical transformation of input and output commands of each installed actuator can be found. For verifying performance of this proposed control allocation method, simulations with the robust trajectory tracking design of a torpedo-like underwater vehicle with four fins, four rudders, and one thruster are executed in this investigation. Full article

(This article belongs to the Special Issue Design and Application of Actuators with Multi-DOF Movement)

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12 pages, 297 KiB

Open AccessCommunication

Nonlinear Gaussian Filter with Multi-Step Colored Noise

by Yidi Teng, Shouzhao Sheng and Yubin Zheng

Actuators 2022, 11(4), 103; https://doi.org/10.3390/act11040103 - 29 Mar 2022

Cited by 1 | Viewed by 1807

Abstract

Color noise is a special kind of noise often occurring in localization systems, and it is more suitable than the general Gaussian white noise to model time dependence due to time delay or high-frequency sampling. This paper derives a nonlinear Gaussian filtering framework [...] Read more.

Color noise is a special kind of noise often occurring in localization systems, and it is more suitable than the general Gaussian white noise to model time dependence due to time delay or high-frequency sampling. This paper derives a nonlinear Gaussian filtering framework for multi-step colored noise systems using noise whitening techniques and Bayes rule. Meanwhile, the cubature rule is used to solve the Gaussian-weighted integral in the proposed Gaussian filtering framework, resulting in an analytic form of posterior state estimate. Compared with the existing nonlinear filtering algorithms, the proposed method has obvious advantages in colored noise systems because it fully takes into account the time dependence of colored noise. Finally, the effectiveness and advantages of the proposed algorithm are verified with a classical target tracking system. Full article

(This article belongs to the Special Issue Resilient Control and Estimation in Networked Systems)

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23 pages, 3382 KiB

Open AccessArticle

Wind Turbine Pitch Actuator Regulation for Efficient and Reliable Energy Conversion: A Fault-Tolerant Constrained Control Solution

by Hamed Habibi, Ian Howard and Silvio Simani

Actuators 2022, 11(4), 102; https://doi.org/10.3390/act11040102 - 28 Mar 2022

Cited by 4 | Viewed by 2309

Abstract

Motivated for improving the efficiency and reliability of wind turbine energy conversion, this paper presents an advanced control design that enhances the power regulation efficiency and reliability. The constrained behavior of the wind turbine is taken into account, by using the barrier Lyapunov [...] Read more.

Motivated for improving the efficiency and reliability of wind turbine energy conversion, this paper presents an advanced control design that enhances the power regulation efficiency and reliability. The constrained behavior of the wind turbine is taken into account, by using the barrier Lyapunov function in the analysis of the Lyapunov direct method. This, consequently, guarantees that the generated power remains within the desired bounds to satisfy the grid power demand. Moreover, a Nussbaum-type function is utilized in the control scheme, to cope with the unpredictable wind speed. This eliminates the need for accurate wind speed measurement or estimation. Furthermore, via properly designed adaptive laws, a robust actuator fault-tolerant capability is integrated into the scheme, handling the model uncertainty. Numerical simulations are performed on a high-fidelity wind turbine benchmark model, under different fault scenarios, to verify the effectiveness of the developed design. Furthermore, a Monte-Carlo analysis is exploited for the evaluation of the reliability and robustness characteristics against the model-reality mismatch, measurement errors and disturbance effects. Full article

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19 pages, 2066 KiB

Open AccessArticle

Design of a Semiactive TMD for Lightweight Pedestrian Structures Considering Human–Structure–Actuator Interaction

by Christian A. Barrera-Vargas, Javier Naranjo-Pérez, Iván M. Díaz and Jaime H. García-Palacios

Actuators 2022, 11(4), 101; https://doi.org/10.3390/act11040101 - 28 Mar 2022

Cited by 2 | Viewed by 2260

Abstract

Lightweight pedestrian structures constructed with high strength-to-weight ratio materials, such as fiber-reinforced polymers (FRP), may experience large accelerations due to their lightness, thus overcoming the serviceability limit state. Additionally, uncertainties associated with human–structure interaction phenomena become relevant. Under these circumstances, variations in pedestrian [...] Read more.

Lightweight pedestrian structures constructed with high strength-to-weight ratio materials, such as fiber-reinforced polymers (FRP), may experience large accelerations due to their lightness, thus overcoming the serviceability limit state. Additionally, uncertainties associated with human–structure interaction phenomena become relevant. Under these circumstances, variations in pedestrian actions could modify the modal properties of the coupled human–structure system and classical approaches based on passive Tuned Mass Dampers (TMD) do not offer an effective solution. An alternative solution is to use a Semiactive TMD (STMD), which includes a semiactive damper that, when properly designed, may be effective for a relatively broad frequency band, offering a robust solution when significant uncertainties are present. Thus, this paper presents a design methodology for the design of STMDs applied to lightweight pedestrian structures including human–structure and actuator–structure interaction. A multiobjective optimization procedure has been proposed to simultaneously minimize structure acceleration, inertial mass, and maximum damper force. The methodology has been applied to a lightweight FRP footbridge. Realistic simulations, including system uncertainties, interaction phenomena, nonlinear damper model, noise-contaminated signals, and the practical elements (in-line digital filters) needed for the successful implementation of the control law, validate the methodology. As a conclusion, the STMD is more effective than its passive counterpart in both, canceling the response or achieving similar performance with significant lower inertial mass. Full article

(This article belongs to the Special Issue Actuators and Dampers for Vibration Control: Damping and Isolation Applications)

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14 pages, 4576 KiB

Open AccessArticle

Development of Air Bearing Stage Using Flexure for Yaw Motion Compensation

by Hak-Jun Lee and Dahoon Ahn

Actuators 2022, 11(4), 100; https://doi.org/10.3390/act11040100 - 28 Mar 2022

Cited by 1 | Viewed by 2871

Abstract

This paper presents an air bearing stage that uses flexure for yaw motion compensation. The proposed stage realizes motion in three degrees of freedom (DOF), which are the X, Y, and Θ_z directions. To work with Θ_z as the [...] Read more.

This paper presents an air bearing stage that uses flexure for yaw motion compensation. The proposed stage realizes motion in three degrees of freedom (DOF), which are the X, Y, and Θ_z directions. To work with Θ_z as the rotational motion of the stage, we applied a flexure consisting of four bar linkages. The stage from a previous study in which flexure is applied to compensate for yaw motion error has the limitation of increasing the structural stiffness of the stage due to the rotational stiffness. In this study, we propose a combination of a new stage structure and flexure to ensure the high structural stiffness of the stage and the very low rotational stiffness of the flexure at the same time. Modeling and design optimization were performed to apply adequate flexure to the proposed stage. Experiments were carried out to verify yaw motion error compensation and the performance of the stage. The proposed stage has a maximum yaw motion error of 0.86 arcsec during the scanning motion and 48 ms settling time, while the stepping motion is improved by 34.2% compared to the previous study. Full article

(This article belongs to the Section Actuators for Manufacturing Systems)

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16 pages, 2085 KiB

Open AccessArticle

Multi-Agent Reinforcement Learning with Optimal Equivalent Action of Neighborhood

by Haixing Wang, Yi Yang, Zhiwei Lin and Tian Wang

Actuators 2022, 11(4), 99; https://doi.org/10.3390/act11040099 - 25 Mar 2022

Cited by 1 | Viewed by 2148

Abstract

In a multi-agent system, the complex interaction among agents is one of the difficulties in making the optimal decision. This paper proposes a new action value function and a learning mechanism based on the optimal equivalent action of the neighborhood (OEAN) of a [...] Read more.

In a multi-agent system, the complex interaction among agents is one of the difficulties in making the optimal decision. This paper proposes a new action value function and a learning mechanism based on the optimal equivalent action of the neighborhood (OEAN) of a multi-agent system, in order to obtain the optimal decision from the agents. In the new Q-value function, the OEAN is used to depict the equivalent interaction between the current agent and the others. To deal with the non-stationary environment when agents act, the OEAN of the current agent is inferred simultaneously by the maximum a posteriori based on the hidden Markov random field model. The convergence property of the proposed methodology proved that the Q-value function can approach the global Nash equilibrium value using the iteration mechanism. The effectiveness of the method is verified by the case study of the top-coal caving. The experiment results show that the OEAN can reduce the complexity of the agents’ interaction description, meanwhile, the top-coal caving performance can be improved significantly. Full article

(This article belongs to the Special Issue Intelligent Control of Flexible Manipulator Systems and Robotics)

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14 pages, 687 KiB

Open AccessArticle

Cooperation-Based Risk Assessment Prediction for Rear-End Collision Avoidance in Autonomous Lane Change Maneuvers

by Young Seop Son and Wonhee Kim

Actuators 2022, 11(4), 98; https://doi.org/10.3390/act11040098 - 25 Mar 2022

Cited by 2 | Viewed by 2303

Abstract

In this study, we present an innovative approach to risk assessment for rear-end collision avoidance using a cooperation concept for an autonomous lane change system. A Kalman filter is designed to estimate the longitudinal acceleration and predict the relative longitudinal position, velocity, and [...] Read more.

In this study, we present an innovative approach to risk assessment for rear-end collision avoidance using a cooperation concept for an autonomous lane change system. A Kalman filter is designed to estimate the longitudinal acceleration and predict the relative longitudinal position, velocity, and acceleration. Risk assessment is performed using the predicted motion of the object vehicle in the target lane. The cooperation concept is proposed to improve the flexibility of the lane change. If the risk assessment for the lane change indicates collision risk, the cooperativeness of the driver of the object vehicle is determined. If the driver of the object vehicle is regarded as a cooperative driver, within the original lane, the ego vehicle moves toward the target lane in preparation for the lane change. Subsequently, as soon as the risk assessment indicates that there is no collision risk, the lane change is performed. Thus, unlike conventional methods, the autonomous lane change using the proposed risk assessment can be initiated. Furthermore, the proposed risk assessment using cooperation concept is more flexible compared with previous methods for autonomous lane change in cluttered traffic. Full article

(This article belongs to the Section Actuators for Land Transport)

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Actuators, Volume 11, Issue 4 (April 2022) – 17 articles

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