マルチステップモデル予測安全フィルタ：予測ホライズンの拡大によるチャタリング低減
Multi-Step Model Predictive Safety Filters: Reducing Chattering by Increasing the Prediction Horizon
学習ベース制御器に安全保証を付与するモデル予測安全フィルタにおいて、入力補正をより長いホライズンで考慮することでチャタリングを低減し、ドローン実験で4倍以上の改善を示した。
著者: Federico Pizarro Bejarano, Lukas Brunke, Angela P. Schoellig
分類: cs.RO, cs.LG, cs.SY, eess.SY
原文アブストラクト
Learning-based controllers have demonstrated superior performance compared to classical controllers in various tasks. However, providing safety guarantees is not trivial. Safety, the satisfaction of state and input constraints, can be guaranteed by augmenting the learned control policy with a safety filter. Model predictive safety filters (MPSFs) are a common safety filtering approach based on model predictive control (MPC). MPSFs seek to guarantee safety while minimizing the difference between the proposed and applied inputs in the immediate next time step. This limited foresight can lead to jerky motions and undesired oscillations close to constraint boundaries, known as chattering. In this paper, we reduce chattering by considering input corrections over a longer horizon. Under the assumption of bounded model uncertainties, we prove recursive feasibility using techniques from robust MPC. We verified the proposed approach in both extensive simulation and quadrotor experiments. In experiments with a Crazyflie 2.0 drone, we show that, in addition to preserving the desired safety guarantees, the proposed MPSF reduces chattering by more than a factor of 4 compared to previous MPSF formulations.
