Application of the IMPACT structure on bilateral teleoperation

Teleoperation systems are expected to play an important role in daily healthcare and wellness applications. Time-delays typically cause stability and performance problems in these systems. As a remedy for such problems in position-error based bilateral teleoperations, a control algorithm is proposed which is derived as a robust modification of a Smith predictor structure for time-delay compensation. The considered modification is based on an application of the Internal model principle an control together (IMPACT). The resulting algorithm allows rejection of disturbances from a known class that act at the output of the slave side of the teleoperated system. To build this structure for a certain teleoperation system, the dynamics of both master and slave manipulator need to be known. The mass moments of inertia en viscous friction coefficients of both master and slave manipulators are required to build this structure for a certain teleoperation system. The parameters of the master and slave manipulators, i.e. the mass moments of inertia and viscous friction coefficients, which are required to design suitable local controllers are obtained by means of frequency response function measurements. Simulations have been performed on the test-setup. The outcome of the simulations was that the reference can be followed reasonably well and most of the disturbance is absorbed fast. Besides that, the steady-state value of the output remains the same with and without the disturbances applied. In all cases, smaller values for the controller parameters n, T0 and ε can be selected to improve the control performance, however at the cost of decreasing the robustness property. Eventually, some experiments are done on the real-time test-setup. These experiments are done for both a control structure with and without the IMPACT structure and disturbance absorber. For the control structure with the IMPACT structure and disturbance absorber, the steady-state output remains the same as the reference, in contrary to the structure without the IMPACT structure and disturbance absorber. Furthermore, the offset in the error is removed. To improve the experiments, better tracking is needed. This can partly be obtained by adding a Coulomb-friction compensator, which is also investigated in experiments and has positive effect on the error. Besides that, different disturbance estimators can have a positive effect on the tracking as well by absorbing the noise better.