Abstract
An adaptive saturated neural network (NN) controller is developed for 6 degree-of-freedom (6DOF) spacecraft tracking, and its hardware-in-the-loop experimental validation is tested on the ground-based test facility. To overcome the dynamics uncertainties and prevent the large control saturation caused by the large tracking error at the beginning operation, a saturated radial basis function neural network (RBFNN) is introduced in the controller design, where the approximate error is counteracted by an adaptive continuous robust term. In addition, an auxiliary dynamical system is employed to compensate for the control saturation. It is proved that the ultimate boundedness of the closed-loop system is achieved. Besides, the proposed controller is implemented into a testbed facility to show the final operational reliability via hardware-in-the-loop experiments, where the experimental scenario describes that the simulator is tracking a planar trajectory while synchronizing its attitude with the desired angle. Experimental results illustrate that the proposed controller ensures that the simulator can track a preassigned trajectory with robustness to unknown inertial parameters and disturbances.
Highlights
In recent few decades, spacecraft control has been attracting widespread interest because of its typical orbit applications, such as formation flying, construction of space station, and space surveillance and capturing, rendezvous, and docking
An adaptive controller is first proposed such that the 6 degree-of-freedom (6DOF) tracking objective is realized
An adaptive controller is synthesized by introducing a saturated radial basis function neural network (RBFNN) and a feasible auxiliary dynamical system, which results in the high accuracy tracking
Summary
Spacecraft control has been attracting widespread interest because of its typical orbit applications, such as formation flying, construction of space station, and space surveillance and capturing, rendezvous, and docking. To realize the theoretical results in practical applications, the air-bearing ground test facilities have been developed [18, 19] and some controllers have been validated by hardware-in-the-loop experiments [20,21,22,23,24,25,26]. For spacecraft operations subject to parametric uncertainties, adaptive controllers are designed and the related experimental validations are conducted on the ground test facilities [20, 21]. This paper seeks to address the controller design for 6DOF spacecraft tracking operations subject to unknown inertial parameters and disturbances. The most remarkable result in this work is that the proposed NN saturated controller is validated by hardware-in-the-loop experiments which are conducted on the ASTERIX facility.
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