Figure 2.

Dynamic walking model controlled by CPG controller with feedback. (A) Pendulum-like legs are controlled by motor commands for hip torques $T_1$ and $T_2$, with sensory feedback of leg angle and ground contact “GC” relayed back to controller. (B) Controller produces alternating motor commands versus time, which drive (C) leg movement $\mathrm{\theta }$. Sensory measurements of leg angle and ground contact in turn drive the CPG. (D) Resulting motion is a nominal periodic gait (termed a “limit cycle”) plotted in state space $\dot{\theta }$ versus $\mathrm{\theta }$. (E) Discrete perturbation to the limit cycle can cause model to fall.