The research of real-time estimation method on tether parameters for tethered satellite

Most existing control methods of tethered satellite system were established on the knowing of tether parameters, but how to get the parameters needs to be solved. In this paper, a real-time estimator is developed to get the parameters. Firstly, we analyze the shortcomings resulting from directly solving the system equations to get tether parameters. Secondly, the equations are simplified and the corresponding problems are thoroughly investigated. And lastly, combing the measurements of a three-axis tether tensiometer with the information of attitude sensor, we use the Extended Kalman Filter to estimate the parameters in real time. The proposed estimator not only reduces the complexity of system model, but also improves the parameters´ precision. Simulation results verify the validity of this method.