The composite hierarchical control of multi-link multi-DOF space manipulator based on UDE and improved sliding mode control

Abstract

The problem of manipulating objects cooperatively for multi-link multi-degree of freedom space manipulator is very challenging because of the multisource disturbances, including nonlinear coupling, model uncertainties, and external disturbances. To solve this issue, a composite hierarchical control strategy is proposed, which has two layers. In inner layer, uncertainty and disturbance estimator (UDE) is employed to estimate the composite uncertainty that comprises the effect of multisource disturbances and compensate for it, producing the decoupled system. Furthermore, taking the error in UDE estimation into consideration, the chattering-eliminating sliding mode control is designed to suppress it in the outer layer. However, the obtained controller requires the measurement of joint velocities apart from joint positions. To address this issue, a robust velocity observer that employs the UDE-estimated uncertainty is proposed. The notable feature of the proposed design is that it requires neither accurate plant model nor any information about the uncertainty. Also, the design requires only joint position measurements for its implementation. Finally, to demonstrate the effectiveness of the composite hierarchical controller, the simulations of a planar dual-arm manipulator system and the comparisons of the proposed method with the other existing designs are presented.

Unified neural output-constrained control for space manipulator using tan-type barrier Lyapunov function

“…In Wang (2011) and Wang and Xie (2009a;2009b;2012), several adaptive tracking controllers were developed for a free-floating space manipulator by utilizing adaptive inverse dynamics, prediction error based adaptation, and passivity based adaptation, respectively. Chu et al (2015) presented a composite hierarchical control strategy for a space manipulator based on the improved sliding mode control and an uncertainty and disturbance estimator. In Yu and Chen (2015), an observer-based augmented adaptive controller was designed for a flexible-joint space manipulator by introducing the singular perturbation theory.…”

UDE-based task space tracking control of uncertain robot manipulator with input saturation and output constraint

“…Combined with NSDF and UDE, a novel task space tracking controller is first proposed for uncertain robot manipulators with input saturation and output constraints. Compared with most existing UDE-based controllers for robot manipulators without input saturation and output constraints [28,29,30,31,32], the proposed control scheme has more extensive applications.…”

Robust finite-time trajectory tracking control for a space manipulator with parametric uncertainties and external disturbances

“…In a study by Flores-Abad et al 19,20 an optimal control strategy was developed for a space manipulator to capture a tumbling object in orbit with uncertainties in the initial and final boundary conditions. Chu et al 21 proposed a composite hierarchical control strategy for a space manipulator based on the improved sliding mode control and an uncertainty and disturbance estimator. In a study by Shi et al 22 two types of controllers, that is, a sliding mode controller and a nonlinear model predictive controller, were carried out for the robust coordinated control of a dual-arm space robot in the presence of system uncertainties.…”