Figure 2.

Control framework of hybrid walker. Locomotion task is divided into two different phases and managed by two separate branches. Heuristics swing controller (orange blocks) controls swing leg with a low-cost position-based approach. Learning-based stance controller (blue blocks) adopts NN policy for controlling. Assistive branch (red block) is active only on the real robot for compensating reality gap. Clock signal $\varphi$ is a periodic ramp signal that increases from 0.0 to 1.0 throughout a gait period.