Abstract
In this paper, a compliant robotic manipulator is proposed as a mechanism to approximate the mechanical properties of the human trunk during wheelchair propulsion. This manipulator is a variant of the conventional Stewart Platform, modified by the addition of spring elements in series with the linear actuators. The spring elements add a compliance resembling the passive stiffness of the human trunk without muscle actuation. An optimization routine, using matrix stiffness analysis, was used to investigate the effects of varying platform geometries, actuator arrangement and spring stiffness upon the bending response of the platform. This quasi-static approach was then used to find the optimum geometry to approximate the response of the human trunk in flexion and extension. Without using the actuators, the passive platform only resembles the actual trunk response at a small segment of range of motion.
