Model-assisted extended state observer-based computed torque control for trajectory tracking of uncertain robotic manipulator systems

Abstract

Computed torque control is an effective control scheme for trajectory tracking of robotic manipulators. However, computed torque control requires precise dynamic models of robotic manipulators and is severely affected by uncertain dynamics. Thus, a new scheme that combines a computed torque control and a novel model-assisted extended state observer is developed for the robust tracking control of robotic manipulators subject to structured and unstructured uncertainties to overcome the disadvantages of computed torque control and exploit its merits. The model-assisted extended state observer is designed to estimate and compensate these uncertain dynamics as a lumped disturbance online, which further improves the disturbance rejection property of a robotic system. Global uniform ultimate boundedness stability with an exponential convergence of a closed-loop system is verified through Lyapunov method. Simulations are performed on a two degree-of-freedom manipulator to verify the effectiveness and superiority of the proposed controller.

Robust composite nonlinear feedback control for uncertain robot manipulators

“…where l min ðQÞ is the minimum eigenvalue of Q and d is the upper bound in closed region k vk 2 < e. It can be seen from equation (24) that when k vk 2 < e, to make _ V < 0, we choose k xk 2 ! ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi e d 4l min ðQÞ s From equations (22) and (24), we deduce that the condition for system convergence is k xk 2 ! ffiffiffiffiffiffiffiffiffiffiffiffiffi e d 4l min ðQÞ q .…”

“…Yin and Pan 21 proposed a robust adaptive control method to significantly reduce the relatively tracking errors of six-degree-of-freedom (DOF) industrial robots under both external disturbances and parametric uncertainties. Chen et al 22 proposed a new scheme that combines a computed torque control and a novel model-assisted extended state observer. In the simulation, a two-DOF manipulator is performed to verify the effectiveness and superiority of the proposed controller.…”

“…From equations(22) and(24), we deduce that the con-dition for system convergence is k xk 2 ! ffiffiffiffiffiffiffiffiffiffiffiffiffi e d 4l min ðQÞ q.…”

Terminal Traction Control of Teleoperation Manipulator With Random Jitter Disturbance Based on Active Disturbance Rejection Sliding Mode Control

“…To remedy modeling uncertainties and external disturbances, in [7], the author used a fuzzy compensator in CTC and achieved the trajectory tracking of three joint manipulators. In [8], the extended state observer is adopted to estimate the constructed and unstructured uncertainties and is successfully applied to the trajectory tracking of a 2-joint manipulator.…”

Finite-time tracking control for uncertain robotic manipulators using backstepping method and novel extended state observer

“…Different from traditional linear or nonlinear observers, ESO treats the lumped uncertainty as an additional state variable of the original system, then estimates it with the help of feedback function. Owing to the characteristics of satisfactory disturbance estimation, simple structure, and convenient implementation, ESO-based controllers are widely used in various practical mechatronic systems, such as robotic manipulators 25 and wheeled mobile robots. 26 For complex coupling system, classic ESO is employed to decouple the system by regarding the coupling term as a part of lumped uncertainty.…”