Planar dynamics and control of space-based flexible manipulators with slewing and deployable links

Space manipulators present several features uncommon to ground-based robots: they are highly flexible, often mobile, and have a degree of redundancy. As space robots become more complex, efficient algorithms are required for their simulation and control. The present study uses an order N algorithm, based on the Lagrangian approach and velocity transformations, to simulate the planar dynamics of an orbiting manipulator with arbitrary number of slewing and deployable flexible links. The relatively general formulation accounts for interactions between orbital, librational, slewing, deployment, and vibrational degrees of freedom, and thus is applicable to a large class of manipulator systems of contemporary interest. Validity of the formulation and computer code is established through verification of energy conservation and comparison with particular cases reported by other investigators. A parametric analysis of the system dynamics is carried out. Several factors are considered: initial disturbances, variation of system parameters, number of manipulator links, and maneuver profiles. The study suggests significant coupling between the rigid body motion and structural vibrations. It was found that the system's flexibility can significantly affect the manipulator's performance. A nonlinear controller based on the Feedback Linearization Technique is developed to regulate the rigid degrees of freedom. A linear quadratic regulator is designed to suppress the manipulator and platform vibrations.