This paper addresses the performance of force-reflecting interfaces ("haptic displays"). We suggest that an important measure of performance is the dynamic range of achievable impedances -- "Z-Width" -- and that an impedance is achievable if it satisfies a robustness property such as passivity. Several factors affecting ZWidth -- sample-and-hold, inherent interface dynamics, displacement sensor quantization, and velocity filtering -are discussed. A set of experiments designed to evaluate these factors is described, and experimental results are presented. A striking result is that inherent interface damping exerts an overwhelming influence on Z-Width.
J. Edward Colgate, J. Michael Brown