On parameter estimation of space manipulator systems using the angular momentum conservation

Abstract

To accomplish tasks with high accuracy, advanced control strategies that benefit from the knowledge of system parameters are required. However, during operation some of them may change, or be unknown. In this paper, a novel parameter estimation method is proposed, which is based on the conservation of the angular momentum of a space manipulator system in the free-floating mode. The estimated parameters are combinations of spacecraft, manipulator and payload parameters and render the system full dynamics identified and applicable to model-based control. The algorithm requires only measurements of joint angles and rates, and spacecraft attitude and angular velocity. No information about spacecraft and joint accelerations or joint torques, which include substantial noise, is required. Thus, in contrast to other methods using the equations of motion, the proposed method is insensitive to sensor noise. Moreover, it does not require the prior knowledge of any system parameters and can be applied to free-floating systems with more than one manipulators. The application of the proposed method is illustrated by a 3D example.