The scope of this paper is to present a novel gait methodology in order to obtain an efficient walking capability for an original walking free-leg hexapod structure (WalkingHex) of tri-radial symmetry. Torque in the upper (actuated) spherical joints and stability margin analyses are obtained based on a constraint-driven gait generator. Therefore, the kinematic information of foot pose and angular orientation of the platform are considered as important variables along with the effect that they can produce in different gait cycles. The torque analysis is studied to determine the motor torque requirements for each step of the gait so that the robotic structure yields a stable and achievable pose. In this way, the analysis of torque permits the selection of an optimal gait based on stability margin criteria. Consequently, a gait generating algorithm is proposed for different types of terrain such as flat, ramp or stepped surfaces. Angle of slope of terrain (rad) Foot spacing angle (rad) Foot spacing radius (m) Foot i Gravitational Coefficient 9.81 (ms−2) Hexapod rotation (rad) Optimal hexapod rotation (rad) Magnitude of stability margin i (m) Maximum torque in system (N m) Optimal translation (m) Overall system stability margin (m) Platform pitch (rad) Platform translation (m) Prismatic joint i Set of integers Torque in upper spherical joint i (N m) Upper spherical joint i 
Pre-gait analysis using optimal parameters for a walking machine tool based on a free-leg hexapod structure