Stabilization Through Gyration: A Wave Variable Approach to High Frequency Force Feedback in Telerobotics

High frequency force feedback to a user is commonly recognized as vital to achieving a realistic telerobotic experience. However, the feedback of measured forces can trigger contact instabilities when interacting with stiff environments. We present a novel feedback approach based on wave variable design, taking advantage of two wave features. First, stability is independent of lag or filtering. Secondly, wave signals inherently describe power flow, thus connecting stability to signal conditioning. The resulting force feedback architecture combines the best of the traditional position-position and position-force methods with an additional element typically not seen in telerobotic controllers – a gyrator. It is stable regardless of the environment stiffness, transmits high frequency forces without roll-off, and is even tolerant to delay. We verify this performance with simple experimental tests, investigate the effects of the gyrator, and show that it plays a critical role in maintaining such robust stability.