Stability, Transparency, and Quantization Error Noise in Bilateral Teleoperation

 

In bilateral teleoperation using impedance control, controller parameters such as stiffness, damping, time delay, and quantization affect the quality of the haptic feedback portrayed to the operator. By increasing the stiffness (proportional gain), better transparency can be achieved. This means the user can feel more accurately what the teleoperated robot is interacting with. Unfortunately, increasing stiffness decreases system stability and increases noise due to quantization error. I investigated the way varying these parameters affects user performance completing teleoperated tasks, how realistic users feel the force feedback is, and how much users liked the force feedback.

 

In my teleoperation experiment, users palpated an artificial tissue to search for a stiffer region. In each trial they used a controller with different stiffness and filtering parameters. Increasing noise had a negative impact on the way users like the force feedback, but did not significantly hurt task performance. Decreasing stability (even beyond the system passivity) had no negative effect on user performance or likeability. By understanding the impacts that balancing parameters like these have on user interations with teleoperators, we can design better controllers, resulting in the best performance and likeability.