Validation of Flatness-Based Feedforward Control for a Four-Chain Crane Manipulator

Flatness-based feedforward trajectory control is experimentally validated for a crane manipulator that suspends a flexible metal sheet by four chain hoists each positioned by an overhead crane gear. For a desired spatial trajectory of the sheet the control inputs of the individual drives are calculated by an inverse dynamics model that takes the load sway dynamics, an approximated dynamic transfer behaviour of the controlled drive axes and the stiffness of the payload into account. A forward kinematics measurement model enables an estimation of the actual pose of the platform from measured drive positions and chain inclinations. Experimental results show the effect of the control concept.