A new control method of flexible-joint manipulator with harmonic drive

2020 ◽  
Vol 234 (9) ◽  
pp. 1868-1883
Author(s):  
Guocai Yang ◽  
Yechao Liu ◽  
Minghe Jin
Keyword(s):  
Control Method ◽  
Controller Design ◽  
Joint Stiffness ◽  
Adaptive Controller ◽  
Harmonic Drive ◽  
Flexible Joint ◽  
Assignment Method ◽  
Uncertain Dynamics ◽  
Tracking Controller ◽  
Flexible Joint Manipulator

Considerable elasticity and nonlinear friction caused by harmonic transmission challenge the performance of flexible-joint manipulators. The uncertain dynamics of manipulator and the inadequate measurable states also limit the controller design. A new control method is proposed to address these problems, achieving the precise motion control of the flexible-joint manipulator. The method consists of three cascaded controllers: an adaptive controller, a torque-tracking controller, and a motor controller. The adaptive controller was adopted to generate the desired torque ensuring the robustness for uncertain dynamics. The torque-tracking controller derived the position compensation for motor control according to the torque error. As the elastic torque is under control, the vibration caused by harmonic drive can be eliminated. The motor was controlled based on poles-assignment method and friction compensation. The Kalman observer based on the Brownian motion model observed both velocity and the high-order derivatives of torque sensing. The stability of the control method was strictly proved. Calibration was performed on each joint to obtain the required joint stiffness and motor friction parameters. The control method was verified on a single joint and the frequency response of the system was obtained. The results show that the controller has good performance. The controller was realized on the self-developed seven-degree-of-freedom manipulator. The results reveal that the controller has high-precision tracking performance.

scholarly journals Cascaded Control of Flexible-Joint Robots Based on Sliding-Mode Estimator Approach

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Genliang Xiong ◽  
Jingxin Shi ◽  
Haichu Chen
Keyword(s):  
Controller Design ◽  
Sliding Mode ◽  
Joint Stiffness ◽  
Perturbation Approach ◽  
Regular Form ◽  
Flexible Joint ◽  
Flexible Joint Robots ◽  
Highly Nonlinear ◽  
Position Controller ◽  
High Bandwidth

The inherent highly nonlinear coupling and system uncertainties make the controller design for a flexible-joint robot extremely difficult. The goal of the control of any robotic system is to achieve high bandwidth, high accuracy of trajectory tracking, and high robustness, whereby the high bandwidth for flexible-joint robot is the most challenging issue. This paper is dedicated to design such a link position controller with high bandwidth based on sliding-mode technique. Then, two control approaches ((1) extended-regular-form approach and (2) the cascaded control structure based on the sliding-mode estimator approach) are presented for the link position tracking control of flexible-joint robot, considering the dynamics of AC-motors in robot joints, and compared with the singular perturbation approach. These two-link position controllers are tested and verified by the simulation studies with different reference trajectories and under different joint stiffness.

scholarly journals Neural Networks Approximator Based Robust Adaptive Controller Design of Hypersonic Flight Vehicles Systems Coupled with Stochastic Disturbance and Dynamic Uncertainties

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Guoqiang Zhu ◽  
Lingfang Sun ◽  
Xiuyu Zhang
Keyword(s):  
Controller Design ◽  
Tracking Error ◽  
Adaptive Controller ◽  
Stochastic Disturbance ◽  
Hypersonic Flight ◽  
Flight Vehicles ◽  
Uncertain Dynamics ◽  
Robust Adaptive ◽  
And Performance ◽  
Dynamic Uncertainties

A neural network robust control is proposed for a class of generic hypersonic flight vehicles with uncertain dynamics and stochastic disturbance. Compared with the present schemes of dealing with dynamic uncertainties and stochastic disturbance, the outstanding feature of the proposed scheme is that only one parameter needs to be estimated at each design step, so that the computational burden can be greatly reduced and the designed controller is much simpler. Moreover, by introducing a performance function in controller design, the prespecified transient and performance of tracking error can be guaranteed. It is proved that all signals of closed-loop system are uniformly ultimately bounded. The simulation results are carried out to illustrate effectiveness of the proposed control algorithm.

The Model-free Adaptive Composite Control Method for Permanent Magnet Linear Motor

2015 ◽  
Vol 7 (2) ◽  
pp. 30-44
Author(s):  
Rongmin Cao ◽  
Su Zhong ◽  
Shizhen Liu
Keyword(s):  
Permanent Magnet ◽  
Control Method ◽  
Controller Design ◽  
Adaptive Controller ◽  
Linear Motor ◽  
Modeling And Control ◽  
Composite Control ◽  
Model Free ◽  
Permanent Magnet Linear Motor ◽  
Force Ripple

A composite control method based on the model-free adaptive control is applied to the position or speed control of the linear motor. The model-free adaptive controller (MFAC) broke through the classical PID controller design of linear framework, is a kind of new controller, it' structure is adaptive and a kind of integration of modeling and control method. The composite control method includes an adaptive feedforward compensator which is designed to eliminate or suppress the effects of inherent force ripple for a permanent magnet linear motor (PMLM). Simulation results show that compared with PID control, the proposed composite control algorithm is more effective for the strong coupling of nonlinear system and difficult to realize stable control. And the response performance of the system is realized.

A model-based PID-like motion control method for flexible-joint manipulator with harmonic drives

2021 ◽  
pp. 095440622110369
Author(s):  
Guocai Yang ◽  
Yechao Liu ◽  
Junhong Ji ◽  
Minghe Jin ◽  
Songhao Piao
Keyword(s):  
Position Control ◽  
Control Method ◽  
Joint Torque ◽  
Dynamics Model ◽  
Motion Error ◽  
Flexible Joint ◽  
Speed Range ◽  
Position Controller ◽  
Flexible Joint Manipulator ◽  
Better Than

A novel control method is proposed to achieve high trajectory tracking precision, for flexible-joint manipulators. The method consists of three major parts: joint torque generator, joint torque tracker and motor position controller. The expected torque is generated by a PID controller based on the manipulator’s rigid dynamics model. In the torque tracker, motor position is corrected in both feedback and feedforward ways. Finally, the motor position controller is responsible to track the corrected motor trajectory to achieve the torque and position control. To suppress nonlinear friction, a disturbance observer is also implemented. The method is verified with a seven-DOFs manipulator. Simulation and experimental results show that, the proposed method is efficient and practical to suppress vibration caused by flexible transmission and disturbance due to friction. As result, high positioning accuracy is achieved in a certain wide working speed range. The no-load motion accuracy is better than 0.6 mm with a manipulator whose length is 1.8 meter, and the motion error is less than 3 mm with loading of four kilograms.

Vibration Control of Redundant Flexible-Joint Manipulators

1997 ◽  
Vol 119 (1) ◽  
pp. 119-125
Author(s):  
Fengfeng Xi
Keyword(s):  
Numerical Simulations ◽  
Vibration Control ◽  
Control Method ◽  
Optimization Technique ◽  
Main Idea ◽  
The Other ◽  
Control Law ◽  
Flexible Joint ◽  
Flexible Joint Manipulator

Presented in this paper is a method for controlling vibrations of a redundant flexible-joint manipulator. The main idea behind this method is to utilize joint redundancy to minimize the change in the manipulator inertia, so that a simple gain-fixed control law can be used to control joint vibrations. For this purpose, two optimal joint trajectory generators are proposed; one is based on the extended Jacobian method and the other is based on an optimization technique. Numerical simulations are provided to demonstrate the effectiveness of the proposed control method.

Sign in / Sign up

Export Citation Format

Share Document