CONTROL OF A FLEXIBLE SPACE ROBOT EXECUTING A DOCKING MANEUVER

This paper is concerned with a flexible space robot executing a dockin g maneuver with a target whose motion is not known a priori. The dynam ical equations of the space robot are first derived by means of Lagran ge's equations and then separated into two sets of equations suitable for rigid body maneuver and vibration suppression control. For the rig id-body maneuver, on-line feedback tracking control is carried out by means of an algorithm based on Lyapunov-like methodology and using on line measurements of the target motion. For the vibration suppression, LQR feedback control in conjunction with disturbance compensation is carried out by means of collocated sensor/actuator pairs dispersed alo ng the flexible arms. Problems related to the digital implementation o f the control algorithms, such as the bursting phenomenon and system i nstability, are discussed and a modified discrete-time control scheme is developed. A numerical example demonstrates the control algorithms.