Adaptive synchronized control for coordination of multirobot assembly tasks

Coordination of multirobot systems has received extensive studies in the past decade. The majority of previous approaches require a complex setup of the hybrid position/force-control architecture, and have not fully addressed the coordination problem when the robots are not kinematically constrained but perform a common task. In this paper, we propose to use a new coordination scheme that is more straightforward and easier to implement and is applicable to a wider area. The basic idea of the new coordination strategy is to use the concept of motion synchronization, since the problem of coordinating multiple manipulators is basically the problem of maintaining certain kinematic relationships amongst robots. The key to the success of the new method is to ensure that each manipulator tracks its desired trajectory while synchronizing its motion with other manipulators' motions, so that differential (or synchronization) position errors amongst manipulators converge to zero. The controller, designed by incorporating the cross-coupling technology into an adaptive-control architecture, successfully guarantees asymptotic convergence to zero of both position tracking and synchronization errors simultaneously. Experiments and simulations on multirobot assembly systems demonstrate the effectiveness of the approach.