Joint Torque Control of a Collaborative Robot Based on Active Disturbance Rejection With the Consideration of Actuator Delay

2017 ◽  
Author(s):  
Tianyu Ren ◽  
Yunfei Dong ◽  
Dan Wu ◽  
Guolei Wang ◽  
Ken Chen
Keyword(s):  
Disturbance Rejection ◽  
Controller Design ◽  
Robot Manipulator ◽  
Torque Control ◽  
Joint Torque ◽  
System Stability ◽  
Current Loop ◽  
Robot Dynamics ◽  
Harmonic Drive ◽  
Active Disturbance Rejection

The application of a robot manipulator to the task of parts assembling or collaboration with human workers requires compliant control and intrinsic safety. As a result, it is necessary to exert accurate torque on each joint of the robot through torque sensing and implementing closed-loop joint torque control. This torque servo system is required to track reference torque signals while operating under the influence of motor friction, flexibility of the harmonic drive, noise from the sensor, robot dynamics modelling error and other unknown certainties, resulting in large control efforts. This paper focuses on providing better compliance control for collaborative robots and proposes a joint torque controller design under development with active disturbance rejection concept. The controller is designed through a novel extended state observer to estimate and compensate for the unmodelled dynamics of the system, nonlinearly variable motor friction, and other uncertainties. Then, a simple proportional differential controller is designed to produce control law. In spite of the remarkable performance in dealing with the mechanical dynamics of the joint actuator, the original controller does not work well with the electrical factor of the joint actuator due to the limited current loop bandwidth in the hardware of motor and driver. To eliminate the detrimental effect of the time delay in current servo, a predictive output method based on a nonlinear tracking differentiator (TD) is used to improve the controller within the framework of active disturbance rejection control. Both simulations and experiments are conducted on a prototype one degree of freedom manipulator with a joint torque sensor. The results demonstrate the enhancement of both the system stability and disturbance rejection performances. Based on the proper treatment of actuator delay, the dominant effect of the motor friction and the flexibility of the harmonic drive has been reduced to insignificance. Moreover, the proposed controller is easy to implement because the explicit dynamic model of the system is not required.

Active Disturbance Rejection Controller Design for Electric Vehicle Traction System

2014 ◽  
Vol 953-954 ◽  
pp. 1406-1412
Author(s):  
Yu Min Wang ◽  
Qing Fan
Keyword(s):  
Electric Vehicle ◽  
Control Strategy ◽  
Disturbance Rejection ◽  
Controller Design ◽  
Current Loop ◽  
Low Velocity ◽  
Brushless Dc ◽  
Tracking Differentiator ◽  
Active Disturbance Rejection ◽  
Traction System

In some low velocity electric vehicle system, Brushless DC motor is used for the main traction motor. However, the low-velocity stability should be guaranteed, especially with the suddenly-changing load, the velocity response should be more quick and the overshoot should be small, all of above can make the vehicle more comfortable. The traction system is controlled by a current loop and a velocity loop, so a new method is proposed, that PI control strategy is in the current loop and the active disturbance rejection controller is in the velocity loop to restrain the bad effect results from suddenly-changing load. This active disturbance rejection controller is composed of a tracking differentiator, an extended state observer, a nonlinear state error feedback controller, and etc. The parameters of the controller are optimally designed, and the simulation results show that this control strategy can effectively restrain the suddenly-changing load and improve the vehicle’s low velocity performance.

scholarly journals Active Disturbance Rejection Control for Position Tracking of Electro-Hydraulic Servo Systems under Modeling Uncertainty and External Load

Actuators ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 20
Author(s):  
Manh Hung Nguyen ◽  
Hoang Vu Dao ◽  
Kyoung Kwan Ahn
Keyword(s):  
Angular Velocity ◽  
Disturbance Rejection ◽  
Lyapunov Theory ◽  
Tracking Performance ◽  
System Stability ◽  
Position Tracking ◽  
Parametric Uncertainties ◽  
Active Disturbance Rejection Control ◽  
Active Disturbance Rejection ◽  
Disturbance Rejection Control

In this paper, an active disturbance rejection control is designed to improve the position tracking performance of an electro-hydraulic actuation system in the presence of parametric uncertainties, non-parametric uncertainties, and external disturbances as well. The disturbance observers (Dos) are proposed to estimate not only the matched lumped uncertainties but also mismatched disturbance. Without the velocity measurement, the unmeasurable angular velocity is robustly calculated based on the high-order Levant’s exact differentiator. These disturbances and angular velocity are integrated into the control design system based on the backstepping framework which guarantees high-accuracy tracking performance. The system stability analysis is analyzed by using the Lyapunov theory. Simulations based on an electro-hydraulic rotary actuator are conducted to verify the effectiveness of the proposed control method.

Automated steering controller design for vehicle lane keeping combining linear active disturbance rejection control and quantitative feedback theory

2018 ◽  
Vol 232 (7) ◽  
pp. 937-948 ◽  
Author(s):  
Zhengrong Chu ◽  
Christine Wu ◽  
Nariman Sepehri
Keyword(s):  
Disturbance Rejection ◽  
Control Method ◽  
Controller Design ◽  
Active Disturbance Rejection Control ◽  
Quantitative Feedback Theory ◽  
Steering Control ◽  
Parameter Uncertainties ◽  
Active Disturbance Rejection ◽  
Disturbance Rejection Control ◽  
Lane Keeping

In this article, a new automated steering control method is presented for vehicle lane keeping. This method is a combination between the linear active disturbance rejection control and the quantitative feedback theory. The structure of the steering controller is first determined based on the linear active disturbance rejection control, then the controller is tuned in the framework of the quantitative feedback theory to meet the prescribed design specifications on sensitivity and closed-loop stability. The parameter uncertainties of the vehicle system are considered at the tuning stage. The proposed steering controller is simulated and tested on a scale vehicle. Both the simulation and experimental results demonstrate that the scale vehicle controlled by the proposed controller is able to perform the lane keeping. In the experiments, the lateral offset between the scale vehicle and the road centerline is regulated within the acceptable ranges of ±0.03 m during straight lane keeping and ±0.15 m during curved lane keeping. The proposed controller is easy to be implemented and is simple without requiring complex calculations and measurements of vehicle states. Simulations also show that the control method can be implemented on a full-scale vehicle.

scholarly journals Design of active disturbance rejection controller for compass-like biped walking

2018 ◽  
Vol 15 (3) ◽  
pp. 172988141877684 ◽  
Author(s):  
Sumian Song ◽  
Chong Tang ◽  
Zidong Wang ◽  
Yinan Wang ◽  
Gangfeng Yan
Keyword(s):  
Limit Cycle ◽  
Disturbance Rejection ◽  
Controller Design ◽  
Linear Time ◽  
Biped Robot ◽  
Transverse Coordinate ◽  
Linear Time Invariant ◽  
Active Disturbance Rejection ◽  
Unstable Limit Cycle ◽  
Coordinate Control

This article proposes an active disturbance rejection controller design scheme to stabilize the unstable limit cycle of a compass-like biped robot. The idea of transverse coordinate transformation is applied to form the control system based on angular momentum. With the linearization approximation, the limit cycle stabilization problem is simplified into the stabilization of an linear time-invariant system, which is known as transverse coordinate control. In order to solve the problem of poor adaptability caused by linearization approximation, we design an active disturbance rejection controller in the form of a serial system. With the active disturbance rejection controller, the system error can be estimated by extended state observer and compensated by nonlinear state error feedback, and the unstable limit cycle can be stabilized. The numerical simulations show that the control law enhances the performance of transverse coordinate control.

Trajectory Tracking Control for a Robotic Manipulator Using Nonlinear Active Disturbance Rejection Control

2017 ◽  
Author(s):  
Mohammed Ali ◽  
Charles K. Alexander
Keyword(s):  
Disturbance Rejection ◽  
Control Method ◽  
Robot Manipulator ◽  
Tracking Performance ◽  
Active Disturbance Rejection Control ◽  
Parameter Uncertainties ◽  
External Disturbances ◽  
Trajectory Tracking Control ◽  
Active Disturbance Rejection ◽  
Disturbance Rejection Control

The tracking performance of a robot manipulator is controlled using nonlinear active disturbance rejection control (ADRC). The proposed method does not require the complete knowledge of the plant’s parameters, and external disturbances since it is based on the rejection and estimation of the unknown internal dynamics and external disturbances. The proposed method is simple and has minimal tuning parameters. The robustness of the proposed method is discussed against parameter uncertainties and disturbances. First, the mathematical model of the manipulator is developed. ADRC theory is explained. The manipulator is represented in ADRC form. ADRC’s tracking performance for the joints and end-effector is compared to the tracking performance of the robust passivity (RP) control. The simulations prove that the proposed control method achieves good tracking performance compared to RP control. It is shown that ADRC has a lower energy consumption compared to RP control by calculating the power in the input signals.

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