Mutual Impedance-Based Force/Velocity Transmission Improvement for Bilateral Teleoperation

Tackling communication delays attracts interest in improving the stability and transparency of bilateral teleoperation. This study presents a novel concept; mutual impedance. Under the delays, this impedance is intrinsic in four-channel acceleration-based bilateral control (4ch ABC). In 4ch ABC, wave propagations can characterize the transmissions of force and velocity, which are described in distributed-parameter systems. The delays induce interference between applied force and velocity response and decrease transparency. The mutual relationship between force and position controllers can explain the interference. The proposed mutual impedance is the indicator of the impact of the relationship. This study notes that the impedance comprises a ratio of force and position controllers. Thus, a force proportional-integral (PI) controller with a gain constraint between the position controller is introduced. One-degree-of-freedom (1-DOF) motion experiments compare the proposed method with conventional methods in superiority. The applicability of the proposed approach to delay fluctuations and multi-DOF motion is verified through 3-DOF manipulators.