A methodology for the incorporation of arbitrarily-shaped feet in passive bipedal walking dynamics

A methodology for implementing arbitrary foot shapes in the passive walking dynamics of biped robots is developed. The dynamic model of a walking robot is defined in a way that allows shape-dependent foot kinetics to contribute to the robot's dynamics, for all convex foot shapes regardless of the exact foot geometry: for the developed method, only the set of points describing the foot profile curve is needed. The method is mathematically derived and then showcased with an application. The open-source pose estimation system OpenPose is used to determine the foot profile that enables the rigid-foot passive robot to reproduce the ankle trajectory of the actively powered, multi-DOF human foot complex. The passive gait of the biped robot walking on the specified foot shape is simulated and analyzed, and a stable walking cycle is found and evaluated. The proposed model enables the study of the effects of foot shape on the walking dynamics of biped robots, eliminating the necessity of solely using simple, and analytically defined geometric shapes as the walking robots' feet. The method can be used for foot shape optimization towards achieving any desired walking pattern in walking robots.