Uncoupled Stability of a Haptic System with Position-Velocity Sampling

In typical haptic simulation systems, sampled position from encoders is utilized to compute the virtual environment force. For dynamic environments, velocity is numerically approximated using sampled position. In this paper, we analytically studied the uncoupled stability of a haptic simulation system when the discrete velocity needed to implement a damper-spring virtual environment came from sampling analog velocity. Since typical analog velocity sensors add inertia to the system or contain ripple, we implemented a high-pass filter to estimate the analog velocity from a potentiometer analog position output. We analytically and experimentally assessed the uncoupled stability for this system for various filter cut-off frequencies and sampling rates.