In Vivo Measurement of Human Tissue Compliance

We present a method for measurement of human tissue compliance in vivo using a commercial haptic interface to apply known step changes in force while recording the resulting displacements. We introduce our system, the Softcometer (SOFT-tissue COmpliance METER). Our motivation was to improve the compliance realism of our Virtual Haptic Back model, but there are many potential applications for this method. We present calibration of the haptic interface, static and dynamic compliance measurement techniques, measurement of contracted muscle compliances, and several important issues affecting our results.