Operator-based Robust Nonlinear Tracking Control for A Human Multi-joint Arm-like Manipulator with Unknown Time-varying Delays

In this paper, an operator-based robust nonlinear tracking control for a human multi-joint arm-like manipulator with unknown time-varying delays is proposed by using robust right coprime factorization approach and a forward predictive operator. That is, first, considering the uncertainties of dynamic model consist of measurement error and disturbances, a nonlinear feedback control scheme is designed to eliminate effect of uncertainties. Second, an operator controller based on real measured data from human multi-joint arm viscoelasticity is presented to obtain desired motion mechanism of human multi-joint arm viscoelastic properties, the unknown time-varying delays are described by a delay operator, and the forward predictive operator is designed to compensate the effect of CNS during human multi-joint arm movements and to remove the effect of unknown time-varying delays while the real online measured data of human multi-joint arm viscoelasticity is fed to the designed operator controller. Finally, the effectiveness of the proposed design scheme is confirmed by the simulation results based on experimental data.