Cooperative control of multiple space manipulators

Abstract

This research concerns the development of cooperative control of two spacecraft mounted two-link manipulators as they reposition a common payload. Lagrangian formulation is used to determine the system equations of motion. Lyapunov stability theory is used to develop the cooperative control by using a reference trajectory and reference actuator torques. Polynomial curves represent potential reference trajectories. Numerical methods select specific reference trajectories to minimize the disturbance torque transmitted to the spacecraft during the payload repositioning maneuver. The reference actuator torques are selected to minimize weighted norms of the torques. Analytical and experimental models of planar motion are used to study the performance of different cooperative controllers. The fifth order polynomial reference trajectory leads to superior performance in terms of spacecraft attitude accuracy, actuator torque magnitude, payload repositioning accuracy, and maneuver time. The higher order polynomial reference trajectory results in only minor improvement in performance. The experimental results verify the concept of cooperative control