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Sliding-Seeking Control: Model-Free Optimization with Safety Constraints
Proceedings of The 4th Annual Learning for Dynamics and Control Conference, PMLR 168:1100-1111, 2022.
Abstract
This paper considers the design of online model-free algorithms for the solution of convex optimization problems with a time-varying cost function. We propose an online switched zeroth-order algorithm where: i) different vector fields are implemented based on whether constraints are satisfied; and, ii) zeroth-order dynamics are leveraged to obtain estimates of the (time-varying) gradients in the algorithmic updates. The zeroth-order strategy is suitable for cases where the optimizer has access to functional evaluations of the cost and constraints, but has no knowledge of their functional form. The proposed online algorithm guarantees finite-time feasibility (while avoiding projections) and it exhibits asymptotic stability to a neighborhood of the optimal trajectory of the time-varying problem. Results are established for cost functions that are strictly convex and twice continuously differentiable. Illustrative numerical results are presented to showcase the main properties of the algorithm.