Achieving a cooperative behavior in a dual-arm robot system via a modular control structure

In this paper the problem of achieving a cooperative behavior in a dual-arm robot systemisaddressed.Acontrolstrategyisconceivedinwhichonerobotispositioncontrolledanddevoted to task execution, whereas a suitable compliance is conferred to the end effectoroftheotherrobottocopewithunavoidablemisalignmentbetweenthetwoarmsandtaskplanning inaccuracies. A modular control structure is adopted that allows the selectionof the proper operating mode for each robot, depending on the task requirements. Theproposed approach is experimentally tested in two different tasks involving the tworobots in the laboratory setup. First, a parts-mating task of peg-in-hole type is executed;the robot carrying the peg is position controlled, whereas the robot holding the hollowpart is controlled to behave as a mechanical impedance. Then, a pressure-forming taskis executed, in which a disk-shaped tool is required to align with a flat surface whileexerting a desired pressure; in this case, the robot carrying the disk is position controlled,whereas the robot holding the surface is force controlled.