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This paper proposes a new algorithm based on model following control to recover the un compensated slave disturbance on time delayed motion control systems having contact with environment. In the previous works, a modified Communication Distur bance Observer (CDOB) was shown to be successful in ensuring position tracking in free motion under varying time delay (11), (12). However, experiments show that due to the imperfections in slave plant Disturbance Observer (DOB) when there is rapid change of external force on the slave side, as in the case of environment contact, position tracking is degraded. This paper first analyzes the effect of environment contact for motion control systems with disturbance observers. Following this analysis, a model following controller scheme is proposed to restore the ideal motion on the slave system. A virtual plant is introduced which accepts the current from the master side and determines what the position output would be if there was no environment. Based on the error between actual system and model system, a discrete time sliding mode controller is de signed which enforces the real slave system to track the virtual slave output. In other words, convergence of slave position to the master position is achieved even though there is contact with environment. Experi mental verification of the proposed control scheme also shows the improvement in slave position tracking under contact forces.

In this paper motion control systems with delay in measurement and control channels are discussed and a new structure of the observer-predictor is proposed. The feature of the proposed system is enforcement of the convergence in both the estimation and prediction of the plant output in the presence of the variable, unknown delay in both measurement and in control channels. The estimation is based on the available data -undelayed control input, the delayed measurement of position or velocity and the nominal parameters of the plant -and does not require apriori knowledge of the delay. The stability and convergence is proven and selection of observer and the controller parameters are discussed. Experimental results are shown to illustrate the theoretical predictions.Upravljanje gibanjem u sustavu s mrežnim kašnjenjem. U ovom je radu razmotren sustav upravljanja gibanjem uz prisutno kašnjenje u mjernom i upravljačkom komunikacijskom kanalu te su predložene nove strukture estimacije/predikcije iznosa kašnjenja. Svojstvo predloženog sustava je poboljšanje konvergencije estimacije/predikcije izlaza iz procesa u prisustvu promjenjivog i nepoznatog kašnjenja u mjernom i upravljačkom kanalu. Estimacija se zasniva na dostupnim podacima -upravljačkom signalu bez kašnjenja, mjerenim signalima položaja ili brzine te nazivnim parametrima procesa-i ne zahtjeva a-priori poznavanje iznosa kašnjenja. Dokazana je stabilnosti i konvergencija sustava upravljanja. Odabran je estimator, a definirani su i parametri regulatora. Prikazani su eksperimentalni rezultati kojima se ilustrira valjanost teoretskih rezultata.

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