Input-Shaped Link Motion for Attitude Control of Underactuated Planar Space Robot Equipped with Flexible Appendages

Control of a space robot without actuators on the main body is an underactuated control problem. As stabilization methods, various methods such as time-varying feedback controllers, discontinuous feedback controllers, center manifold-based methods, zero-dynamics methods, and sliding mode controllers have been proposed. However, the past studies have not considered an underactuated space robot equipped with flexible appendage, such as solar panels. If the manipulators were simply controlled to achieve the main body attitude using the past controllers with out taking the flexible appendage into consideration, residual vibration would be remained even after the link motion has finished. In order to suppress the residual vibration on the flexible appendage, we apply the input-shaping technique to the link motion of the underactuated plane space robot. Numerical simulations are carried out to validate the proposed method for a planar two-link space robot with flexible appendage. The results show that the proposed method was capable of not only changing the link angles and the main body attitude, but also suppressing the residual vibration on the flexible appendage.