Curve Tracking Control for Legged Locomotion

Recent developments in legged mobile robots call for curve tracking control laws that enable safe movements in complex environment. The lateral leg spring (LLS) model captures planar locomotion dynamics that are platform independent. We derive a hybrid feedback control law for the LLS model so that the center of mass of a legged runner follows a curved path in horizontal plane. The control law enables the runner to change the placement and the elasticity of its legs to move in a desired direction. Stable motion along a curved path is achieved using curvature, bearing and relative distance between the runner and the curve as feedback. Constraints on leg parameters determine the class of curves that can be followed. These results are applicable to a wide range of legged robots.