Design of a Nonlinear Position Regulator for Cooperating Hydraulic Manipulators Handling a Rigid Object

In this paper, a nonlinear control scheme is developed for performing a cooperative task by hydraulic manipulators. The goal is to design a controller that allows two or more hydraulic robots to coordinately regulate an object’s position/orientation while maintaining desired internal forces on the object and sharing load. First the dynamic model of the whole system, including hydraulic functions, is derived. Then, a controller is designed, augmented by an on-line updating law to eliminate the steady-state error due to lack of knowledge about the weight of the object. Extended Lyapunov’s second method is used for stability analysis of the control system. The stability of the system is guaranteed by constructing a smooth Lyapunov function. Simulations are performed to substantiate the controller developed.