Gravity-Compensated Robust Control for Micro-Macro Space Manipulators During a Rest to Rest Maneuver

Many space applications require robotic manipulators that have large workspace and are capable of precise motion. Micro-macro manipulators are considered as the best solution to this demand. Such systems consist of a long flexible arm and a short rigid arm. Kinematic redundancy and presence of unactuated flexible degrees of freedom makes it difficult to control micro-macro manipulators. This paper presents a closed-loop control based on artificial constrained motion which helps to keep the end- effector on the prescribed trajectory, while the flexible arm can freely vibrate. The robustness of algorithm is checked against uncertainties of the system, which shows good performance except in the presence of gravity. A gravity compensating term is added to eliminate the drift due to gravity.