Wrench Capability Analysis of a Serial-Parallel Hybrid Leg of a Disney’s Bipedal Robot

One of the most fascinating applications of walking robots is in the film industry, for creating special effects and animatronics. For this reason, the Walt Disney Company is investing efforts to develop bipedal walking robots. A serial-parallel hybrid leg for a humanoid robot was designed by Disney’s team, consisting of a pair of twin hybrid chains whose main body is a 5-bar linkage. This paper analyzes the wrench capability of a planar version simplification of this serial-parallel hybrid leg, aiming to determine the leg’s posture that provides the highest supporting and impulse forces during the robot’s gait. The wrench capability is calculated through Davies’ method. This paper demonstrates that the robot applies higher impulse forces when stepping forward or provides higher resistance forces when landing on the ground if the legs are brought closer to the actuators.