An Equivalent Impedance Characteristics Analysis System for Human-machine Systems

Abstract

In the present paper, we propose a prototype system for analyzing equivalent impedance characteristics of human-machine systems (HMS) taking contact and constraint conditions into account. The system consists of three modules: an HMS modeler, an HMS analyzer, and an HMS visualizer. In the HMS modeler, the equa-tion of motion of the HMS is constructed from the musculoskeletal human model and the multibody object model. In the HMS analyzer, inverse dynamics and muscle tension distribution are solved using motion and force data. Muscle stiffness and viscosity are then computed from a Hill-type muscle tendon complex model. The equivalent impedance is transformed from the muscle space to any point of the object. The result is visualized 3-dimensionally in the HMS visualizer to enhance usefulness of the prototype. Measuring motion and force in a task of regulating the steering wheel with a knob at a constant velocity, equivalent inertia and stiffness at the end effector and around a steering column are calculated. The results show an effectiveness of the equivalent impedance analysis to investigate driver's strategy in a steering maneuver.