A unified inner‐/outer‐loop distributed design for task‐space robust cooperative tracking of uncertain networked manipulators under directed graphs

Abstract

AbstractThis paper investigates task‐space cooperative tracking of networked manipulators with an inner‐/outer‐loop closed control architecture, taking effects of uncertain kinematics, dynamics, disturbances, and unavailable task‐space velocities into account. In the existing related works, the developed distributed cooperative control algorithms require either an open control architecture with torque‐based controllers or the combination of inner/outer loop to be stable with the effects of unknown dynamics being neglected. In contrast, in this work we propose a novel distributed control framework such that a distributed outer‐loop adaptive scheme is developed to achieve task‐space robust cooperative tracking with dynamic effects being considered and without modifying the inner control loop. In particular, a distributed estimator is firstly developed to estimate the desired global task. With this estimated information, distributed cooperative algorithms are presented for two types of inner‐loop controllers to ensure task‐space coordinated tracking asymptotically. If the robot has an open control architecture, the torque‐based distributed controller is provided for task‐space cooperative tracking, which can cover existing related results as a special case. Finally, numerical simulations are provided to show the effectiveness of the proposed designs.