Dynamic heel-strike toe-off walking controller for full-size modular humanoid robots

Abstract

General purpose modular actuators have greatly lowered the difficulty of building and maintaining high degree of freedom humanoid robots. In addition to widely adopted miniature modular humanoid robots, full-size humanoid robots can now be built using such modular actuators. To overcome torque and control bandwidth limitations of modular actuators, such robots tend to have a design principle of relatively short leg length and large foot size. However, the kinematic constraints from such design limit the bipedal mobility of the robot. In this paper, we present an efficient walking controller that utilizes a moving Zero Moment Point (ZMP) trajectory, automatically calculated heel and toe lift motions and a reference foot tilt trajectory to generate a dynamic heel-strike toe-off gait with large stride lengths while overcoming the kinematic constraints. We demonstrate the suggested controller in physically realistic simulations, and on the THOR-RD full-sized humanoid robot.