Run-to-Run Control With Bayesian Optimization for Soft Landing of Short-Stroke Reluctance Actuators

TL;DR

This work tackles reducing end-of-stroke impacts in short-stroke reluctance actuators by introducing a run-to-run control framework that leverages Bayesian optimization to optimize cycle inputs. A model-based current parametrization is used to drive soft landing, with adaptations including adaptive search bounds, point removal, and a net-improvement acquisition function to handle the black-box nature of the cost. The approach is validated through Monte Carlo simulations on a solenoid valve model and experimental tests on multiple valves, showing that R2R-BO yields the best performance and robustness compared to pattern-search and Nelder–Mead baselines. The results imply significant practical impact for extending the life and performance of relutance actuators in industrial switching applications, particularly where position sensing is unavailable or unreliable, and where unit-to-unit variability and temperature effects are nontrivial.

Abstract

There is great interest in minimizing the impact forces of reluctance actuators during commutations, in order to reduce contact bouncing, acoustic noise and mechanical wear. In this regard, a run-to-run control algorithm is proposed to decrease the contact velocity, by exploiting the repetitive operations of these devices. The complete control is presented, with special focus on the optimization method and the input definition. The search method is based on Bayesian optimization, and several additions are introduced for its application in run-to-run control, e.g. the removal of stored points and the definition of a new acquisition function. Additionally, methods for the input parametrization and dimension reduction are presented. For analysis, Monte Carlo simulations are performed using a dynamic model of a commercial solenoid valve, comparing the proposed search method with two alternatives. Furthermore, the control strategy is validated through experimental testing, using several devices from the same ensemble of solenoid valves.

Figures (7)

• Figure 1: Schematic diagram of a reluctance actuator.
• Figure 2: Diagram of the hybrid automaton.
• Figure 3: Linear-travel short-stroke solenoid valve (left) and experimental setup with the valve, a micrometer to limit the maximum gap and an electret microphone to measure the impact noise (right).
• Figure 4: Gap reluctance and its derivative with respect to the gap length.
• Figure 5: Desired position trajectories and nominal current signals for the making (left) and breaking (right) operations.