Non-Model-Based Multiple Impedance Control of Cooperating Robotic Manipulators

The multiple impedance control (MIC) is a model-based algorithm that enforces a designated impedance on all cooperating manipulators, and the manipulated object itself. Although the MIC has appeared as an efficient algorithm, but to apply model-based control laws the system dynamics has to be modeled. Furthermore, computation of the system dynamics even if perfectly known, may require considerable process time at each step for implementing the control law. In this paper, the MIC law is modified to be implemented without using system dynamics, and so is called non-model-based multiple impedance control (NMIC). Consequently, this new MIC law is a quick and more realistic algorithm for implementation in cooperating robotic systems. Developing the NMIC law, a vigorous stability analysis, based on the Lyapunov direct Method, besides error analysis, shows that under the NMIC law all participating manipulators, and the manipulated object exhibit the same designated impedance behavior. Next, the proposed NMIC law is applied on an object manipulation task with two cooperating manipulators while one of them is equipped with a Remote Compliant Centre. The results show good tracking performance even in the presence of impacts due to contact with an obstacle, and also system flexibility. Obtained results reveal the merits of NMIC law as a non-model-based algorithm for object manipulation tasks, which can be implemented with reasonable uncomplicated online computations