In a typical manufacturing task, there are actually several stagesinvolved. First, the workpiece must move from some initial startingposition and make contact with a surface, and then it must perform somecontact task (constrained motion), and finally return to its initiallocation to begin the procedure on the next item. This paper develops aframework which allows a workpiece to move to an unknown surface whoseexact location is not known, perform a hybrid position and force controltask on a surface whose shape is not known, and then return to theinitial starting location. The complete (unified) hybrid task method ispresented as a 6-phase process, and is experimentally evaluated on atwo-link manipulator. The technique performs well experimentally forboth full-order and reduced-order controllers on an unknown straightline surface and an unknown arc surface. Also, the structure couldeasily be adapted to the case of when a surface shape is known exactly.The approach shows promise for some manufacturing applications
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