Legged Robots with Human Morphology: Design and Control

Abstract

This paper presents the design and control of a bio-inspired legged robot with a passive toe joint. This legged robot will be utilized to study human gait and particularly pathological gaits. Hence, the leg structure is designed so that it can generate a similar gait of that of human. In addition, the parts of the legs need to be made of light materials mainly, aluminum and carbon fiber. The locomotion control of the legged robot is designed so that the overall control system with respect to the rolling motion is approximated by the Van der Pol oscillator. The controlled plant, in this case, is modeled as an inverted pendulum. Few control parameters are introduced to modulate the rolling motion and make it adaptive with the stride. The parameters of the locomotion controller can be tuned so that the closed loop system exhibits a stable limit cycle. The controller is then evaluated throughout simulation results using a full model of the biomechanical legs. To validate the simulation model, the Zero Moment Point (ZMP) method is utilized. The ZMP locations are obtained using the parameters of the full simulation model and compared with that of the measured ZMP using the ground reaction forces.