Attitude Decoupling Control of Semifloating Space Robots Using Time-Delay Estimation and Supertwisting Control

Abstract

Dynamic coupling is an inherent behavior of the space robot system, which seriously affects the motion accuracy of the system. This paper focuses on how to guarantee the base attitude stability of semi-floating space robots, from a control perspective, namely, the base attitude decoupling control. The quaternion representation of the system dynamics is derived to avoid the representation singularity of the Euler angles. In consideration of the complicated system dynamics and the limited computing ability of the on-board computer, an efficient decoupling controller is designed based on the time-delay estimation (TDE) and the super-twisting control (STC). Herein, for the proposed TDE-based STC (TDE-STC) scheme, TDE is used to decouple and linearize the nonlinear dynamics, and STC is a second-order sliding mode control (SMC) algorithm which can compensate for the TDE error and drive the state variables to converge to the equilibrium point robustly in finite time. The model-free decoupling principle of TDE is clearly illustrated by comparison with the classical computed-torque control (CTC). The global asymptotical stability analysis of the closed-loop system is proven using the Lyapunov theory and the linear matrix inequality (LMI) theorem. Finally, several comparative simulation studies on a three-dimensional (3-D) space robot system with consideration of joint friction, disturbances, and model uncertainties are conducted to verify the effectiveness of the proposed TDE-STC scheme. The corresponding results show that the TDE-STC scheme can achieve a high-accuracy attitude decoupling performance with both the model-free merits and the chatter-free merits.

Fixed Time Control of Free-Flying Space Robotic Manipulator with Full State Constraints: A Barrier-Lyapunov-Function Term Free Approach

“…For example, Authors in [8] proposed a Proportional Derivative (PD) controller based on the accurate and linearized model of SRM with multiple Control Momentum Gyros (CMGs). Later, many adaptive controllers [9][10][11][12] and robust controllers [13][14][15] were proposed to handle the system uncertainty, disturbance and nonlinearity. Additionally, to improve the transient performance, a number of works showed the interest in achieving a finite converge time of tracking errors, known as Finite Time Control [16][17][18][19][20].…”

Kinodynamic Trajectory Optimization of Dual-Arm Space Robot for Stabilizing a Tumbling Target

“…In order to solve the dynamics coupling between the base and the manipulator, the generalized Jacobian matrix is proposed for single-arm space robots [9]. Zhang et al design an efficient decoupling controller based on the timedelay estimation (TDE) and the supertwisting control (STC), which can linearize the nonlinear dynamics of space robot and drive the state variables to converge to the equilibrium point robustly [10]. Compared with single-arm space robot, multiarm robotic system can perform more dexterous, flexible, and complex tasks [11,12].…”

Variable Structure Control and Its Ground Experimental Test for the Space Station Robot

“…These factors may cause inaccurate joint motion and lead to poor robot performance. To solve these problems, various dynamic feedforward compensation plus PID-like or plus other single-loop feedback control algorithms and computed torque controlbased methods have been proposed, including slidingmode control (SMC) [30][31][32][33][34][35][36] or some other variable structure controllers [37][38][39][40], neural networks [41][42][43][44][45][46], fuzzy control [47,48], and adaptive control [49,50]. However, many of them are only tested in simulations or doublejointed robotic systems and may have more difficulties achieving the expected performance in the multijoint serial robotic system.…”

“…It shows higher efficiency and a better control performance than [22] in the experiment because it combines the PD plus dynamic feedforward compensation and the Bang-Bang control to achieve compensation for the tracking error caused by the modeling uncertainty. One noticeable merit of the proposed method lies in the easier design and application in real robot systems than the controllers designed in [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] because of its simplicity in structure.…”