Development of an Independent Hip Drive for a 2D Biped Walking Machine

Abstract

Bipedal robots have advantages over wheeled or multi-legged robots because they require fewer footholds for locomotion and can traverse a larger percentage of Earth's terrain including discontinuous or rough terrain. The Intelligent Systems and Automation Laboratory (ISAL) at the University of Kansas has developed a two dimensional (2D) biped walker, nicknamed the Jaywalker, in order to study the requirements necessary for a bipedal robot to traverse uneven terrain and successfully regain stability after encountering perturbations. In order to maintain stability over rough terrain, the robot must be capable of controlling each leg independently ensuring foot placement on stable footholds. Foot placement is, therefore, critical for stability since a misstep can cause the robot to slip or distribute its weight unevenly on the foothold causing it to become unstable and fall over. An independent drive system was incorporated into the robot's hip that directly couples the hip motors to the legs, eliminates flexible connections in the power transmission system that can add unnecessary errors, and increases the leg rotation resolution, which all increase the robot's foot placement accuracy. Testing was performed to prove the independent hip drive design can operate within human gait parameters, has the same or better range of motion as a human, and is capable of taking a stable step.