This paper addresses the robust finite-time sliding mode control algorithms for nonlinear bilateral teleoperators in the presence of variable time delays and disturbances. In this paper, the designs of terminal sliding control are proposed to guarantee the finite-time convergence of not only the sliding variables but also the coordination errors on position tracking. The proposed control algorithm is able to ensure finite-time convergence without requiring the relative velocities and power signal in the communication channel. Additionally, the finite-time controller is developed with additional terms of sign and exponential function to tackle the variable time delay between two sides in bilateral teleoperators. The Lyapunov synthesis principle and additional lemmas are exploited to ensure the finite-time stability of the closed-loop system in the presence of delays and disturbance. The situations of free-motion, passive, and non-passive human/environment forces are considered for finite-time convergence without the need of acceleration signals. Finally, numerical examples and experimental studies are carried out to illustrate the effectiveness of the proposed controllers.
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