Experimental evaluation of a complete hybrid position and force task using a two-link manipulator

In a typical manufacturing task, there are actually several stages involved. First, the workpiece must move from some initial starting position and make contact with a surface, and then it must perform some contact task (constrained motion), and finally return to its initial location to begin the procedure on the next item. This paper develops a framework which allows a workpiece to move to an unknown surface whose exact location is not known, perform a hybrid position and force control task on a surface whose shape is not known, and then return to the initial starting location. The complete (unified) hybrid task method is presented as a 6-phase process, and is experimentally evaluated on a two-link manipulator. The technique performs well experimentally for both full-order and reduced-order controllers on an unknown straight line surface and an unknown arc surface. Also, the structure could easily be adapted to the case of when a surface shape is known exactly. The approach shows promise for some manufacturing applications