The Arm-Perturbator: Design of a Wearable Perturbation Device to measure Limb Impedance

Abstract—A method for and the design of a wearable system to measure mechanical impedance, e.g., to measure the stiffness of the human arm during natural movements, is described. With the new setup it will be possible to induce forces up to 1300N within a timeframe of less than 25ms using a defined impact rather than an oscillating force. The approach is compared to various existing solutions, showing the advantages of the new approach. A theoretical analysis of the approach is used for a simulation, in order to optimize the system parameters. Finally, measurements for verifying the simulation and identifying important influences on the system performance are described. Keywords—Arm-Perturbator, arm movements, perturbation analysis, human limb impedance, stiffness measurements. I