A Biped Walking Robot with Prismatic Joints

Abstract

A prismatic-jointed leg mechanism is developed for walking robots. The leg, constructed by combining a pair of parallel links, has two degrees of freedom in the sagital plane; a translational motion at the knee joint, and a rotational motion at the ankle joint. By using the leg, it is possible to control a robot based upon a simple control algorithm, walking at various vertical height of its center of gravity.
In order for the simplicity of the control, all motors for driving the joints are attached at the trunk of the walking robot so as to reduce the mass of the leg. Moreover, the top link of the leg is mechanically constrained to be parallel to the bottom link so as to fix the orientation of the trunk of the robot while walking.
Experimental walking results by using a biped robot, constructed with the developed leg, are shown for verification of the leg mechanism.