Enhancing Bipedal Walking Robot Stability Using Foot Placement and Reversible Switching Surfaces Controller

Human walking has three characteristics: stability, maneuverability, and high efficiency. The ultimate goal of bipedal walkers is to achieve robotic performance with all these three characteristics. In passive bipedal walkers walking down a gentle slope, the only energy source is gravity, resulting in high efficiency within this category of robots. However, maneuverability and stability remain the primary challenges. By designing a proper controller, we can enhance the two other features while still benefiting from good efficiency. In this paper, we design a foot placement controller and merge it with a Reversible Switching Surfaces (RSS) controller to enhance the stable period-one gait of a biped walker with a flat foot model on slopes. The combination of both controllers together improves the stability region by 175% with respect to the passive biped walker.