Multiple Impedance control of cooperative manipulators using virtual object grasp

Multiple impedance control (MIC) is a model-based algorithm that enforces a designated impedance on all cooperating manipulators, the manipulated object, and the moving base if applied on a mobile robotic system. For tuning the inner object forces, it is needed to model the inner forces/torques. For this purpose, the virtual linkage model is introduced to determine the inner forces using the MIC law. Also, the load distribution between end-effectors is modeled. In the following, the MIC law is used to control both path tracking and inner forces tuning when manipulating an object. The moving object is grasped with three cooperating end-effectors either solidly, or flexible. The developed controller is compared to the augmented object control (AOC) where impedance control was applied. Finally, the effects of gain tuning on inner forces are discussed. The obtained results reveal good tracking performance of the proposed MIC controller, besides tuning the object internal forces even in the presence of contact, and system flexibility