scholarly journals A Manipulator Control Method Based on Deep Deterministic Policy Gradient with Parameter Noise

2021 ◽  
Author(s):  
Haifei Zhang ◽  
Xu Jian ◽  
Liting Lei ◽  
Fang Wu ◽  
Lanmei Qian ◽  
...  
Keyword(s):  
Motion Control ◽  
Control Method ◽  
State Variables ◽  
Control Approach ◽  
Environment Model ◽  
Policy Gradient ◽  
The Stability ◽  
Reinforcement Learning Models ◽  
Policy Optimization ◽  
Manipulator Control

Abstract Focusing on the motion control problem of two link manipulator, a manipulator control approach based on deep deterministic policy gradient with parameter noise is proposed. Firstly, the manipulator simulation environment is built. And then the three deep reinforcement learning models named the deep deterministic policy gradient (DDPG), asynchronous advantage actor-critical (A3C) and distributed proximal policy optimization (DPPO) are established for training according to the target setting, state variables and reward & punishment mechanism of the environment model. Finally the motion control of two link manipulator is realized. After comparing and analyzing the three models, the DDPG approach based on parameter noise is proposed for further research to improve its applicability, so as to cut down the debugging time of the manipulator model and reach the goal smoothly. The experimental results indicate that the DDPG approach based on parameter noise can control the motion of two link manipulator effectively. The convergence speed of the control model is significantly promoted and the stability after convergence is improved. In comparison with the traditional control approach, the DDPG control approach based on parameter noise has higher efficiency and stronger applicability.

DUTY-CYCLED SPINNING BASED 3D MOTION CONTROL APPROACH FOR BEVEL-TIPPED FLEXIBLE NEEDLE INSERTION

2018 ◽  
Vol 18 (07) ◽  
pp. 1840017 ◽  
Author(s):  
QIN YAO ◽  
XUMING ZHANG
Keyword(s):  
Motion Control ◽  
Control Method ◽  
Tracking Error ◽  
Open Loop ◽  
Loop Control ◽  
3D Motion ◽  
Control Approach ◽  
Target Error ◽  
The Mean ◽  
Simulation Results

Flexible needle has been widely used in the therapy delivery because it can advance along the curved lines to avoid the obstacles like important organs and bones. However, most control algorithms for the flexible needle are still limited to address its motion along a set of arcs in the two-dimensional (2D) plane. To resolve this problem, this paper has proposed an improved duty-cycled spinning based three-dimensional (3D) motion control approach to ensure that the beveled-tip flexible needle can track a desired trajectory to reach the target within the tissue. Compared with the existing open-loop duty-cycled spinning method which is limited to tracking 2D trajectory comprised of few arcs, the proposed closed-loop control method can be used for tracking any 3D trajectory comprised of numerous arcs. Distinctively, the proposed method is independent of the tissue parameters and robust to such disturbances as tissue deformation. In the trajectory tracking simulation, the designed controller is tested on the helical trajectory, the trajectory generated by rapidly-exploring random tree (RRT) algorithm and the helical trajectory. The simulation results show that the mean tracking error and the target error are less than 0.02[Formula: see text]mm for the former two kinds of trajectories. In the case of tracking the helical trajectory, the mean tracking error target error is less than 0.5[Formula: see text]mm and 1.5[Formula: see text]mm, respectively. The simulation results prove the effectiveness of the proposed method.

scholarly journals Universal Walking Control Framework of Biped Robot Based on Dynamic Model and Quadratic Programming

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Xiaokun Leng ◽  
Songhao Piao ◽  
Lin Chang ◽  
Zhicheng He ◽  
Zheng Zhu
Keyword(s):  
Motion Control ◽  
Dynamic Characteristics ◽  
Control Method ◽  
Constraint Equation ◽  
Biped Robot ◽  
Equation System ◽  
Whole Body ◽  
Optimal Controller ◽  
Control Framework ◽  
The Stability

Biped robot research has always been a research focus in the field of robot research. Among them, the motion control system, as the core content of the biped robot research, directly determines the stability of the robot walking. Traditional biped robot control methods suffer from low model accuracy, poor dynamic characteristics of motion controllers, and poor motion robustness. In order to improve the walking robustness of the biped robot, this paper solves the problem from three aspects: planning method, mathematical model, and control method, forming a robot motion control framework based on the whole-body dynamics model and quadratic planning. The robot uses divergent component of motion for trajectory planning and introduces the friction cone contact model into the control frame to improve the accuracy of the model. A complete constraint equation system can ensure that the solution of the controller meets the dynamic characteristics of the biped robot. An optimal controller is designed based on the control framework, and starting from the Lyapunov function, the convergence of the optimal controller is proved. Finally, the experimental results show that the method is robust and has certain anti-interference ability.

scholarly journals Optimal Fractional Order Based on Fuzzy Control Scheme for Wind Farm Voltage Control with Reactive Power Compensation

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Kamal Elyaalaoui ◽  
Moussa Labbadi ◽  
Mohammed Ouassaid ◽  
Mohamed Cherkaoui
Keyword(s):  
Fractional Order ◽  
Wind Farm ◽  
Reactive Power ◽  
Control Method ◽  
Low Voltage ◽  
Stability Margin ◽  
State Variables ◽  
Control Approach ◽  
System Operator ◽  
Squirrel Cage Induction Generator

Voltage stability margin is ensured through the reactive power resources. In order to generate the reactive power references and ensure the low-voltage ride-through (LVRT) control of a wind farm system based on squirrel cage induction generator, this paper proposed an optimal control approach based on fractional-order (FO) PI-fuzzy-PI (FOPI-fuzzy-FOPI) controller. The proposed control method ensures, also, the demand for active and reactive power predetermined by the transmission system operator (TSO) and satisfies the grid code recommendations. In order to achieve a faster tracking of state variables of the system, the FO operators are optimized using the particle swarm optimization algorithm (PSOA). Using FO operator and PSOA, the responses of the system can be improved. The proposed controller provides additional parameters for better tracking performance and faster convergence can be achieved. Numerical simulation results are presented to analyze the advantages of the proposed control approach to design a physically, realizable controller. The present results are compared with various control methods to show the superiority of the method proposed in this paper.

Man-machine interaction-based motion control of a robotic walker

2020 ◽  
pp. 1-21
Author(s):  
Chengjie Zhang ◽  
Shuai Guo ◽  
Fengfeng (Jeff) Xi
Keyword(s):  
Motion Control ◽  
Control Method ◽  
Fuzzy Controller ◽  
Gait Training ◽  
Recognition Algorithm ◽  
Simulated Patients ◽  
Acceptable Error ◽  
Control Approach ◽  
Robotic Walker ◽  
Force Signal

BACKGROUND: The aging population brings the problem of healthcare and dyskinesia. The lack of mobility extremely affects stroke patient’s activities of daily living (ADL) and decreases their quality of life. To assist these mobility-limited people, a robotic walker is designed to facilitate gait rehabilitation training. OBJECTIVE: The aim of this paper is to present the implementation of a novel motion control method to assist disabled people based on their motion intention. METHODS: The kinematic framework of the robotic walker is outlined. We propose an intention recognition algorithm based on the interactive force signal. A novel motion control method combined with T-S fuzzy controller and PD controller is proposed. The motion controller can recognize the intention of the user through the interactive force, which allows the user to move or turn around as usual, instead of using their hands to control the walker. RESULTS: Preliminary experiments with healthy individuals and simulated patients are carried out to verify the effectiveness of the algorithm. The results show that the proposed motion control approach can recognize the user’s intention, is easy to control and has a higher precision than the traditional proportional–integral–derivative controller. CONCLUSION: The results show that users could achieve the task with acceptable error, which indicates the potential of the proposed control method for gait training.

Theory and Experiments on the Compliance Control of Redundant Robot Manipulators

1990 ◽  
Vol 112 (4) ◽  
pp. 653-660 ◽  
Author(s):  
H. Kazerooni ◽  
K. G. Bouklas ◽  
J. Guo
Keyword(s):  
Degrees Of Freedom ◽  
Control Method ◽  
Robot Manipulators ◽  
Industrial Robot ◽  
Redundant Robot ◽  
Control Approach ◽  
Six Degrees Of Freedom ◽  
The Stability ◽  
Control Methodology ◽  
Theory And Experiments

This work presents a control methodology for compliant motion in redundant robot manipulators. This control approach takes advantage of the redundancy in the robot’s degrees of freedom: while a maximum six degrees of freedom of the robot control the robot’s endpoint position, the remaining degrees of freedom impose an appropriate force on the environment. To verify the applicability of this control method, an active end-effector is mounted on an industrial robot to generate redundancy in the degrees of freedom. A set of experiments are described to demonstrate the use of this control method in constrained maneuvers. The stability of the robot and the environment is analyzed.

Torque control of new energy four wheel hub motor based on distribution algorithm

2021 ◽  
pp. 29-41
Author(s):  
Shuai Leng ◽  
◽  
Liqiang Jin ◽  
Keyword(s):  
Control Method ◽  
The Body ◽  
Torque Control ◽  
State Variables ◽  
Motor Speed ◽  
Control Effect ◽  
New Energy ◽  
Optimal Efficiency ◽  
Stator Flux ◽  
The Stability

Due to the nonlinear, strong coupling and uncertain parameters of the new energy four-wheel hub motor, it is more difficult to control the torque of the motor. In order to solve this problem, a torque control method of the new energy four-wheel hub motor based on the distribution algorithm is proposed. The dynamic model of the new energy four-wheel hub motor is established, and the unmeasurable flux, electric power and other state variables in the motor model are derived according to the degree of freedom of the body. The whole four-wheel hub motor is taken as the research object, and the optimal efficiency of the drive system is taken as the goal, and the distribution algorithm is used to control the electromagnetic torque of the motor. The simulation results show that after the torque control of new energy four wheel hub motor, the driving range of the vehicle is longer, the amplitude of stator flux changes little, the stator current changes and the stability of motor speed are good, and the torque control effect is better.

An observer-based output tracking controller for electrically driven cooperative multiple manipulators with adaptive Bernstein-type approximator

Robotica ◽  
2021 ◽  
pp. 1-25
Author(s):  
Alireza Izadbakhsh
Keyword(s):  
Control Method ◽  
Mathematical Tool ◽  
Bernstein Type ◽  
Control Approach ◽  
Output Tracking ◽  
Polynomial Coefficients ◽  
Output Tracking Control ◽  
Adaptive Laws ◽  
The Stability ◽  
Multiple Manipulators

Abstract Thisarticle presents an observer-based output tracking control method for electrically actuated cooperative multiple manipulators using Bernstein-type operators as a universal approximator. This efficient mathematical tool represents lumped uncertainty, including external perturbations and unmodeled dynamics. Then, adaptive laws are derived through the stability analysis to tune the polynomial coefficients. It is confirmed that all the position and force tracking errors are uniformly ultimately bounded using the Lyapunov stability theorem. The theoretical achievements are validated by applying the proposed observer-based controller to a cooperative robotic system comprised of two manipulators transporting a rigid object. The outcomes of the introduced method are also compared to RBFNN, which is a powerful state-of-the-art approximator. The results demonstrate the efficacy of the introduced adaptive control approach in controlling the system even in the presence of disturbances and uncertainties.

scholarly journals A compliant control method for robust trot motion of hydraulic actuated quadruped robot

2018 ◽  
Vol 15 (6) ◽  
pp. 172988141881323 ◽  
Author(s):  
Teng Chen ◽  
Xuewen Rong ◽  
Yibin Li ◽  
Chao Ding ◽  
Hui Chai ◽  
...  
Keyword(s):  
Motion Control ◽  
Control Method ◽  
Middle Layer ◽  
Bottom Layer ◽  
Hydraulic Cylinder ◽  
Simulation Software ◽  
Lateral Impact ◽  
Software Environment ◽  
Control Approach ◽  
Active Compliance

A motion control approach is proposed for hydraulic actuated quadruped robots, aiming to achieve active compliance and robust motion control. The approach is designed with a structure of three layers. Servo valve-controlled asymmetric hydraulic cylinder model is established to obtain the relationship between the desired torque and the control current signal, which is the bottom layer. The middle layer is based on the virtual model of the leg for active compliance. The upper layer considers the torso posture and velocity into planning the foot trajectories based on the spring loaded inverted pendulum model. Trotting gait simulations are conducted based on the proposed framework in the simulation software environment Webots. The motion control approach has been implemented on a robot prototype SCalf-II (SDU calf), where experiments have been conducted including omnidirectional trotting gait, lateral impact recovery and climbing slopes. The experiments demonstrate that the proposed approach can effectively control the hydraulic actuated robots.

scholarly journals Antisynchronization of Nonidentical Fractional-Order Chaotic Systems Using Active Control

2011 ◽  
Vol 2011 ◽  
pp. 1-13 ◽  
Author(s):  
Sachin Bhalekar ◽  
Varsha Daftardar-Gejji
Keyword(s):  
Active Control ◽  
Fractional Order ◽  
Chaotic Systems ◽  
Control Method ◽  
Value Of Time ◽  
State Variables ◽  
Financial Systems ◽  
The Stability ◽  
First Time ◽  
Active Control Method

Antisynchronization phenomena are studied in nonidentical fractional-order differential systems. The characteristic feature of antisynchronization is that the sum of relevant state-variables vanishes for sufficiently large value of time variable. Active control method is used first time in the literature to achieve antisynchronization between fractional-order Lorenz and Financial systems, Financial and Chen systems, and Lü and Financial systems. The stability analysis is carried out using classical results. We also provide numerical results to verify the effectiveness of the proposed theory.

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