Reliable control for tele-robotics with multi degree of freedom

In this paper, the reliable controller design is considered for multi-degree of freedom-based telerobotics. Time-delay estimation is employed to obtain the unknown dynamics and the external disturbances of robots online and to perform a compensation during the control. The faults of each actuator occur randomly and their failure rates are governed by a set of unrelated stochastic variables satisfying some certain probabilistic distribution. A new unified tele-robotics model is built by assuming the probabilistic distribution-based actuator fault and the input time varying delay. By considering the input time varying delay and the probabilistic actuator faults, we study the problem of the reliable control. By using Lyapunov functional method and stochastic systems theory, actuator distributed-dependent sufficient conditions for the exponentially mean square stability of telerobotics system are obtained in the form of linear matrix inequalities, which can be solved easily by the application of convex optimization algorithms. A simulation example is given to show that: firstly, using the distribution information of the actuator, the maximum effective delay bound can be easily obtained for the tele-robotics system; secondly, the proposed design procedures can also be used when the tele-robotics is without actuator faults; lastly, the proposed reliable controller can stabilize the tele-robotics system with probabilistic actuator faults, which may be unstable under the designed controller without considering the faults of actuator.