Multi‐manipulators coordination for bilateral teleoperation system using fixed‐time control approach

In this paper, the fixed‐time synchronization control problem for bilateral teleoperation system composed of a single master manipulator and multiple cooperative slave manipulators with system uncertainties and external disturbances is addressed. The multiple cooperative slave manipulators have the capability to perform some complex tasks that are difficult or even impossible to be executed by a single slave manipulator. In order to control the multiple slave manipulators handling a common object with faster speed and higher accuracy, a new adaptive neural networks (NNs)–based fixed‐time control scheme is proposed. First, under the assumptions that the slave manipulators are rigidly grasping a nondeformable object, an integrated dynamic model composed of multiple slave manipulators and an object is derived. The object's grasping forces are concealed in the derived dynamics and can be controlled independent of the motion space. Then, a new nonsingular integral terminal sliding mode providing fixed‐time convergence of the velocity and position errors is designed with high‐degree terms and lower‐degree terms. By setting proper initial value of the integral function, the system settling time will be reduced greatly. Moreover, the corresponding adaptive NN‐based fixed‐time control approach is proposed by employing the strong approximation of the NNs. It is proved that the closed‐loop teleoperation system is semiglobally fixed‐time stable and the synchronization errors between the local manipulator and the object will converge to zero in fixed time for any initial condition of the master and the slaves. Finally, simulation and experiment are both performed to verify the effectiveness of the proposed method.