Chapter Three - Uncertainties compensation-based teleoperation control

Abstract

In this chapter, we propose several methods based on wave variables and RBFNN to deal with the uncertainty problems in teleoperation systems, which are mainly caused by the time delays in the communication channel and the dynamics in the actual environment. For the nonlinearity of the dynamic model and the imprecision of the dynamic parameters, the RBFNN-based controller is proposed for compensation. With the advantages of nonlinear function approaching and fast training, RBFNN could be competent for approaching the nonlinear item in the dynamic model and finally realize precise tracking. Experiments to determine the tracking performance were carried out to analyze the effectiveness of introducing RBFNN compensation. For the time-varying delay existing in the communication channel, the wave variable correction-based method was proposed. The traditional wave variable method could ensure the passivity and stability of the system under a constant time delay, but when the delays are time-varying, the stability of the system is disturbed. Thus, the wave variable method with correction item was introduced in this chapter. Trajectory tracking and force reflection experiments showed that the correction-based wave variable method is stable and effective. Besides, since the multichannel structure can improve the transparency and stability of the bilateral teleoperation system, it is necessary to consider the solution when the time delay exists in the communication channel under the multichannel structure. In this chapter, the existence of time delay in a four-channel structure was taken as an example, and we introduced a four-channel scheme-based wave variable method. Theoretical proofs were provided and experiments were carried out to show that the multiple channel-based wave variable method could ensure stability and transparency of the teleoperation system in the case of time delay.