Natural Gradient Descent for Control

Abstract This article bridges optimization and control and presents a novel closed-loop control framework based on natural gradient descent, offering a trajectory-oriented alternative to traditional cost-function tuning. We leverage the Fisher information matrix to formulate a preconditioned gradient descent update that offers flexibility in shaping closed-loop behavior. To this end, the proposed method parameterizes closed-loop dynamics in terms of stationary covariance and an unknown cost function, providing a geometric interpretation of control adjustments. We establish theoretical stability conditions. The simulation results on a rotary inverted pendulum benchmark highlight the advantages of natural gradient descent in trajectory shaping.