Stiffness readout in musculo-skeletal humanoid robot by using rotary potentiometer

We developed an enhanced type of stiffness control module that we can embed in whole body of a musculo-skeletal humanoid robot. This module is a type of nonlinear spring unit. Using one pair units, we can change stiffness of wires, so we can control stiffness of a joint. This stiffness control method is a mechanical one that is superior in rapid response than an electric one using impedance control. A musculo-skeletal robot with these units in whole body can change its joints stiffness in accordance with the situations, so it will realize interaction with people and human life support. This unit is newly adopting rotary mechanism that can reduce friction and adjust stronger force than straight one of prior units, so it can be made small enough for a humanoid robot application. In this paper, we have challenged stiffness readout by using a rotary potentiometer. A rotary potentiometer is low price, tough and very small, so it well suited for a humanoid robot that needs a lot of units within limited spaces.