Vibration Suppressing for Hydraulically Driven Large Redundant Manipulators

The application of large manipulators in servicing and building environments is a field of growing research interest. Typical tasks performed by the manipulators are pumping of wet concrete, handling of loads under difficult conditions and cleaning of aircraft. One of the main problems is the occurence of vibrations induced by hydraulic pressure oscillation and elasticity effects. In order to suppress these vibrations and to coordinate the motion for tracking given trajectories, a nonlinear position control concept is required. In this paper, a particular method is developed for this purpose, taking into account effects of mechanical transmission elements, hydraulic actuators and boom flexibility. As an application, the control of a large-scale manipulator carrying out wet concrete pumping tasks is presented.