Non-linear position control of cooperative hydraulic manipulators handling unknown payloads

Abstract

Abstract In this paper, a non-linear stable 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 specified load sharing between the manipulators as well as desired internal forces on the object. First the complete dynamic model of the whole system is described. Then, a controller is designed, augmented by an on-line updating law to eliminate the steady-state errors due to lack of knowledge about the payload. 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 in this paper. Acknowledgements The authors would like to thank the Natural Science and Engineering Research Council (NSERC) of Canada who provided financial support for this research. The authors would also like to thank International Submarine Engineering Ltd. (ISE), Vancouver, BC, Canada, for providing information about the dynamics and kinematics parameters of the MAGNUM-7 hydraulic manipulator used in the simulations presented here.