Adaptive control of a colleague-like multi-robot system handling a common unknown object

The authors present a technique for controlling a multi-robot system handling an unknown object (payload). It is shown that, when several robots grasp a common object, the resultant coupled dynamic behaviour is irregular in that some well-known properties do not apply. This fact complicates the direct application of existing strategies derived for the control of a single robot. By using model transformation and decomposition, the combined model is regularized and a novel control scheme is proposed in which the payload´s unknown dynamic effects are explicitly considered. The stability of the control strategy is addressed by the generalized energy integral method. It turns out that the control law not only produces the required control torque, but also provides certain internal forces and torques, an essential condition for preventing damage to the workpiece