| A force-feedback loop with position accommodation was successfully used to coordinate robot arms. The control loop adapts to the stiffness of the object being held. The adaptive algorithm uses an adaptive observer. The adaptive control loop was tested experimentally with motion in one dimension and in two dimensions. Objects held were two (2) rubber strips of different widths (one dimensional motion), a spring, and a sheet of cloth (two dimensional motion). The control loop was stable using force feedback in all of the experiments. Convergence of the estimated gain to the correct values was demonstrated in three dimensions using computer simulation. The gain matrices used were not necessarily diagonal, and they were not symmetric in all cases. This made the problem a coupled multi-input, multi-output problem. It was shown that the assumption of a diagonal stiffness matrix can degrade the performance of the system. |
