Control strategy for cooperating disparate manipulators: Non-colocated control of disturbances of a flexible arm

The long term objectives for this research are to use a small robot arm to compliment a large robot arm. Disturbances generated by robot tasks were studied. Available equipment made it convenient to study disturbances generated by an abrasive cut off saw mounted on the tip of a large armed robot, and used to cut through rods and pipes in the range of 0.5 in. to 1.5 in. The abrasive process was modeled as a friction operation. The operation of the cut off saw was performed autonomously and under teleoperated control. The behavior was stable in both cases for a P-D joint control algorithm. It was found that broad band excitation during the cutting operation is capable of exciting arm natural frequencies to above the third natural frequency of the arm. The direction of cut changed the modes excited due to the change in coupling coefficients.