Projection-Based Force-Reflection Algorithms With Frequency Separation for Bilateral Teleoperation

Projection-based force-reflection (PBFR) algorithms have been previously demonstrated to substantially improve stability characteristics of bilateral teleoperators with communication delays; however, the transient response of the PBFR algorithms suffers from relatively slow force convergence. As a result, the high-frequency component of the reflected force is lost during the initial phase of contact with the environment, which has a strong negative effect on the haptic perception of the environmental stiffness and texture. In this paper, a new type of PBFR algorithms are developed which solve the aforementioned problem. The new algorithms are based on the idea to separate different frequency bands in the force-reflection signal and apply the PBFR principle to the low-frequency component, while reflecting the high-frequency component directly. Both theoretical analysis and experimental results are presented; the results obtained confirm that the new algorithms fundamentally improve force convergence without a negative effect on stability of the teleoperator system with communication delays.