Fully distributed cooperation for networked uncertain mobile manipulators
This paper investigates the fully distributed cooperation scheme for networked nonholonomic mobile manipulators. To achieve cooperative task allocation in a distributed way, an adaptation-based estimation law is established for each robotic agent to estimate the desired local trajectory. In addition, wrench synthesis is analyzed in detail to lay a solid foundation for tight cooperation task. Together with the estimated task, a set of distributed adaptive control is proposed to achieve motion synchronization of the mobile manipulator ensemble over a directed graph with a spanning tree irrespective of the kinematic and dynamic uncertainties in both the mobile manipulators and the tightly grasped object. The controlled synchronization alleviates the performance degradation caused by the estimation/tracking discrepancy during transient phase. Persistent excitation condition and noisy Cartesian-space velocities are totally avoided. Furthermore, the proposed scheme is independent from the object's center of mass by employing formation-based task allocation and task-oriented strategy. These attractive attributes facilitate its practical application. It is theoretically proved that convergence of the cooperative task tracking error is guaranteed. Simulation results validate the efficacy and demonstrates the expected performance of the proposed scheme.
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