Observer-based control for manipulators with moving bases

Much research work has been dedicated in the last years to the control of manipulators (rigid, flexible, or with flexible joints) with stationary bases. To enlarge the workpace of manipulators, to avoid obstacles or singularities, and to open new application areas a new generation of robots has been created. This class contains the mobile manipulator which is basically a manipulator mounted on a vehicle. In this case not only the kinematics but also the dynamics of the manipulator is affected by the base motion and coupling forces. Since it is usually difficult, if not impossible, to model these, a novel control method is proposed in this paper. The main idea is to design a regular manipulator motion controller that considers the dynamic coupling effects as external disturbances. Here, robustness is assured by estimating and compensating for the coupling effects together with any other disturbances rather than computing them.