Tool center point control of a large-scale manipulator using absolute position feedback

Abstract

This work presents a trajectory generation and control scheme for point-to-point motion of a hydraulically driven large-scale manipulator considering various constraints such as joint position, joint velocity, task space, and volumetric flow rate constraints. Trajectories for the absolute position and orientation of the tool center point are generated by a constrained quadratic optimization problem based on differential kinematics. The use of an efficient quadratic problem solver renders the algorithm real-time capable. The control loop uses a high-quality measurement feedback in Cartesian coordinates from a robotic total station network to precisely position the tool center point. The proposed control scheme is compared to a time-optimal solution in simulations. Simulations further show the redundancy exploitation and robustness of the algorithm. Experiments give insight into the tracking quality and show that the achieved positioning accuracy is in the sub-centimeter range.