Continuous Optimization for Control of Finite-State Machines via Time-Freezing in NOSNOC

Wim van Roy

Atlas Copco Airpower

Tuesday, February 07, 2023, 11:00 - 11:59

SR 01-012

Systems with Finite-state machines (FSM) are inherently non-smooth due to their finite states. Within optimal control problems, these finite states are often modelled as integer variables resulting in an MINLP problem, a class of problems that are generally hard to solve. An alternative method is to model the problem using time-freezing as proposed by  Nurkanović & Diehl (2022). The method reformulates the original problem into a class of problems with switches. The reformulation can be solved using the Finite Element with Switch Detection method, which avoids the usage of integer variables. This talk generalizes the original method to include multiple states of the state machine based on one switch detection function. It presents some new insights into the reformulation that make the method more computationally attractive. The advantages and disadvantages of the method are illustrated using numerical results from a car gearbox, temperature control and the control of systems with multiple FSM as obtained using the python implementation of NOSNOC.



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Meeting ID: 627 9173 7415
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