The ICP-based controllability criterion and its application to bipedal walking control

In this paper, we define n-step controllability based on the concept of Instantaneous Capture Point (ICP). First, we analyze the underlying constraints of the controllability. A closed-form expression of the controllable region is then derived, providing a concise controllability criterion. This criterion also indicates the upper bound of ICP controller's performance. Furthermore, we introduce an objective function and propose new ICP controllers, which can approach the upper bound, with the analytical solution of the constrained optimization. Simulations are conducted to verify the proposed criterion and ICP controllers.