Formulation of Fatigue Dynamics as Hybrid Dynamical System for Model Predictive Control

The standard fatigue estimation procedure is formulated as a hybrid dynamical system, which subsequently is utilized to calculate an economic terminal cost in MPC. This formulation is enabled by the development of a novel algorithm for continuous stress cycle identification. A second hybrid dynamical system is designed to provide fatigue cost gradients. The formulation turns out to be a powerful generalization of previous fatigue cost formulations, and additionally introduces consideration of past stress into the cost function. Presented closed-loop simulations using a wind turbine model provide insight into the subsystems of the hybrid dynamical system, and show the benefit of memorizing the past. Copyright (C) 2020 The Authors.