An Analytical Study on Trotting at Constant Velocity and Height

Quadrupedal trotting gaits of constant forward velocity and body height are studied. A method is developed, which is structured upon analytical expressions derived from the dynamics of a reduced single-legged model comprised of a point mass, and two actuated rotational joints. The inputs of the method include the robot mass, the leg and actuator properties, and the desired forward velocity, yielding all robot body feasible trajectories and their energy footprints. Thus, the method predicts the maximum forward velocity of a trotting quadruped; it also suggests energetically optimal combinations of body height and step length for a given forward velocity.