Simulating 2D Gaits with a Phase-Indexed Tracking Controller

Tracking controllers produce realistic motion in simulations by mimicking an input motion. However, current time-indexed trackers adhere strictly to the input motion´s timing, causing a lack of robustness. A new phase-indexed tracker for 2D characters can deviate from the input motion´s timing. Compared to time-indexed tracking with a state-of-the-art nonlinear quadratic regulator, phase-indexed tracking can withstand force perturbations up to an order of magnitude larger. The phase-indexed controller employs motion constraints that induce a reduced dynamic for which we can design control policies that incorporate prediction.