Performance of equivalent frequency-dependent damping

An analog input shaper (AIS) was proposed as a means for increasing the virtual impedance range that could be stably displayed by haptic interfaces. The AIS reduces high frequency inputs to haptic interfaces, since high frequency inputs that usually occur during collisions with very stiff virtual objects can induce instabilities. The AIS is composed of an analog high-pass filter, two half-wave rectifiers, and an adder. In this paper, we show analytically that how the AIS works as equivalent frequency-dependent damping. In addition, we present both the numerical simulation results and the virtual wall experiment results using a custom-built 1-DOF haptic interface and show that the AIS can significantly increase the Z-Width.