Nontumbling Gait for Multilegged Robots and Its Directional Normalized Energy Stability Margin

Figure 3

Rotation of CG around the edge of the supporting polygon under the influence of external disturbance 𝐸_𝑖 for robot standing in an arbitrary posture. 𝑃_𝑖 are footholds, and 𝑃^∗_𝑖 are their projections on a horizontal plane. 𝐕(𝐸_𝑖) is input velocity, created by external disturbance energy 𝐸_𝑖, and 𝐕_𝑏 is robot’s body velocity. 𝑆₁ is the plane of CG rotation around 𝑃₁𝑃₂, and 𝑆₂ is a vertical plane of an unstable equilibrium above 𝑃₁𝑃₂. Other variables are defined in Section 3.