Cooperative object manipulation using Non-Model-Based Multiple Impedance Control

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 been 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, based on an approximated feedback linearization control approach, the MIC law is modified to be implemented without using system dynamics. Therefore, this modified MIC law, which is called Non-Model-Based Multiple Impedance Control (NMIC), is a quick and more realistic algorithm for implementation in cooperating robotic systems. Developing the NMIC law, error analysis shows that under the NMIC law all participating manipulators and the manipulated object exhibit the same designated impedance behavior. 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 obtained results show good tracking performance even in the presence of impacts due to contact with an obstacle, and also system flexibility. These results reveal the merits of NMIC as a non-model-based algorithm for object manipulation tasks, while it can be implemented with reasonably limited on-line computations.