Adaptive control for excitation and parameter identification of a three-axis spacecraft simulator with full-state constraints

The three degrees of freedom spacecraft attitude simulator is of vital importance in verifying spacecraft control strategies and many other space techniques. It requires accurate knowledge of simulator inertia parameters which can be identified by a variety of estimation methods under appropriate excitation situation. However, constraints on the rotation range, angular velocity, and torque may lead to a bad parameter estimation performance and cause security problem in excitation process. A new adaptive reorientation controller is proposed in this paper to solve these problems. By deriving the expression of parameter estimation error and analyzing the ill-conditioned problem resulted from the attitude constraint, a preconditioned adaptive parameter estimation law is designed and then combined with a new proposed reorientation controller, such that the errors of parameter identification and reorientation excitation simultaneously converge to zero. And the constraints can also be met. Compared to conventional parameter identification schemes, the proposed controller can simultaneously achieve the closed-loop reorientation excitation for security requirement and the more efficient parameter identification outcome. The effectiveness of the adaptive controller is finally demonstrated by numerical simulations.