Hard contact surface tracking for industrial manipulators with orientation control and (SR) position based force control

摘要

We present a hybrid control concept that solves a wide range of surface tracking tasks for manipulators with defined contact to (moving) rigid objects. The definition of contact includes a contact force between end- effector and work-piece, aswell as orientation angles relative to the surface and the tracking direction.Position based Neural Force Control (NFCP) consists of a hybrid force/position controller that accurately generates contact forces to objects with arbitrary flexibility and uncertain distance or shape. Orientation control is realized by a supplementarymodule in the control loop, using force and position sensor signals.Disturbances in force control are caused by joint friction, thus we developed a special kind of neural friction compensation.NFC-P includes a neural trajectory generating tool for smooth and kinematically valid contact movements, including the possibility to adapt the trajectories to the unknown shape of the surface online.The kinematical mappings guarantee singularity robustness (SR) in the entire workspace.Results from real-time experiments are presented using a 6 DOF industrial manipulator as testbed. The control functions are implemented on a PC based operating system (RCON). All mappings are solved in a cycle-time of 0.5 ms (Pentium PC 166).