Robust adaptive fixed‐time tracking control of 6‐DOF spacecraft fly‐around mission for noncooperative target

Abstract

Summary The fixed‐time relative position tracking and attitude synchronization control problem of a spacecraft fly‐around mission for a noncooperative target in the presence of parameter uncertainties and external disturbances is investigated. Firstly, a novel and coupled relative position and attitude motion model for a noncooperative fly‐around mission is established. Subsequently, a novel nonsingular fast terminal sliding mode (NFTSM) surface is developed, and the explicit estimation of the convergence time independent of initial states is provided. Fair and systematic comparisons among several typical terminal sliding modes show that the designed NFTSM has faster convergence performance than the fast terminal sliding mode. Then, a robust integrated adaptive fixed‐time NFTSM control law with no precise knowledge of the mass and inertia matrix and disturbances by combining the nonsingular terminal sliding mode technique with an adaptive methodology is proposed, which can eliminate the chattering phenomenon and guarantee that the relative position and attitude tracking errors can converge into the small regions containing the origin in fixed time. Finally, numerical simulations are performed to demonstrate the effectiveness of the proposed control schemes.

A new practical robust control of cable‐driven manipulators using time‐delay estimation

“…To effectively settle this issue, a novel STA with TDE was proposed for robot manipulators recently . Exciting results were reported with this method, but improvement can still be made for better performance in the following two aspects: (1) the robust term used in the work of Kali et al, was traditional SM control with linear error dynamics, which may result in slow convergence and low control accuracy around the equilibrium point, and it has been demonstrated that terminal SM (TSM) control can ensure better control performance than the traditional SM one; and (2) the standard STA was used and may lead to relative poor performance under the situation that system states are far from the equilibrium point.…”

Practical adaptive fractional‐order nonsingular terminal sliding mode control for a cable‐driven manipulator

“…It can also be seen from A and B of Figures 6 to 8 that there are five peaks appearing in the control procedure, which are mainly caused by the gravity for the initial one, Coulomb friction, and backlash of planetary gears for the other four. 24 25 26 Moreover, the rapid increasing/decreasing of the tracking errors leads to corresponding rapid increasing/decreasing of the adaptive control gainsK 1 andK 2 , as shown in G and H of Figures 6 to 8. The rapid increasing ofK 1 andK 2 can effectively improve the control precision when the tracking errors attempt to increase, and they sharply decrease when the tracking errors become relative small.…”

“…All three controllers adopted in the simulation studies are experimented on Polaris-I and corresponding control parameters are tuned using the procedures given earlier. Finally, the control parameters for our proposed controller are selected as k 1 = k 2 = k = diag(1,1), = diag (0.99,0.99), a = diag (0.8, 0.8), b = 0.8, m = diag(0.05, 0.1), p = diag(100, 40), 24 25 26 K max =[2, 0.8] T , L = 2 ms, andM= 0.001 × diag (5,5). In addition, a boundary layer of 0.04 is adopted.…”

“…[15][16][17][18][19][20] Originally, linear error dynamics were combined with TDE leading to asymptotic stability, which, however, is not robust enough for some complex systems under strong lumped disturbance. Thus, the terminal sliding mode (TSM) control and its improved version, [21][22][23][24][25][26][27] which can ensure finite-time stability and high tracking precision, were integrated with TDE. [28][29][30] These TDE-based TSM controllers can effectively take advantage of TDE and TSM techniques, resulting in model-free robust controllers while still conquering the practical limitations of their own.…”

Adaptive Fixed-Time Terminal Sliding Mode Control on SE(3) for Coupled Spacecraft Tracking Maneuver

“…Different from the separated control strategy, spacecraft proximity operation needs a precise integral control strategy of coupled 6-DOF motion for the chaser spacecraft [4]. Modeling of coupled rotational and translational relative motions of rigid spacecraft has been receiving great interests in recent years based on different forms, such as dual quaternion [4][5][6][7], three-dimensional (3-D) Euclidean space (Lie group SE(3)) [8][9][10][11], 6-DOF Euler-Lagrange form [12] (translational motion described in LVLH (local-verticallocal-horizontal) frame and rotational motion described by MRPs (modified Rodrigues parameters)) or other forms [13][14][15][16][17][18] (translational motion described in body-fixed frame or LOS (line-of-sight) frame and rotational motion described by MRPs). However, dual quaternion inherits the ambiguities intrinsic of quaternion, which may cause unwinding problem.…”