Fig. 3: Locomotion comparison study experiments.

a, Each policy follows a set of command velocities in x and yaw between 0 and 1 m s⁻¹ and between −1 and 1 rad s⁻¹, respectively. During each velocity pair, the commanded gait is cycled through all gaits, switching every 1 s. This repeated five times over flat, \({h}_{{\rm{terr}}}^{0}\), to very rough terrain, \({h}_{{\rm{terr}}}^{3}\) (shown in Fig. 2) with the average performance being plotted. A number rather than a magnitude indicates the count of experiments that the policy failed. b, Each policy follows a sinusoidal trajectory in x (v_x) and in yaw (ω_z) while switching gaits every 2 s, which is repeated 5 times over \({h}_{{\rm{terr}}}^{0}\) and \({h}_{{\rm{terr}}}^{3}\) terrain. The green highlighted areas indicate transition phases, for which the function and formulation are detailed in ‘Bio-inspired gait scheduler’ in Methods, and the black triangles represent points of failure. c, Policies follow a command of just v_x = 0.5 m s⁻¹ while using a constant trot gait while encountering rectangular steps with a height of 0.05 m, where \(| {\bar{\omega }}_{{\mathrm{B}}}^{{\rm{err}}}|\) is the magnitude of the desired orientation error, FL is front left, FR is front right, RL is rear left and RR is rear right in reference to the robot’s feet.