A suboptimal excitation torque for parameter estimation of a 5-DOF spacecraft simulator

Five degrees of freedom spacecraft simulators are designed to verify spacecraft control strategies, rendezvous and docking techniques. The accurate knowledge of simulator inertia parameters which can be calculated by parameter estimation is of vital importance in these experiments. However, the rotation limits of the simulator must be considered during estimation process. This paper presents an approach to determine a suboptimal excitation torque for the system identification of the inertia parameters. The continuous optimization problem is transcribed into a discrete nonlinear programming problem by integral gauss pseudospectral method. To reduce the effect of noise, the states and inertia parameters are estimated simultaneously by joint filter within Extended Kalman Filter (EKF) or Unscented Kalman Filter (UKF). The proposed method is validated by simulations and the results indicate that this method not only satisfies the constraints of simulator rotation angles, but also improves the efficiency of parameter estimation.