Structured physics-guided neural networks for electromagnetic commutation applied to industrial linear motors

TL;DR

This paper introduces a physics-guided neural network approach for electromagnetic commutation in industrial linear motors, significantly reducing position and commutation errors by modeling parasitic effects more accurately.

Contribution

The paper presents a novel structured neural network model that learns parasitic effects in electromagnetic systems and uses it for improved commutation in industrial linear motors.

Findings

Achieved a 10x reduction in commutation error in driving direction.

Reduced position error by a factor of 4.

Demonstrated effectiveness on real industrial linear motor data.

Abstract

Mechatronic systems are described by an interconnection of the electromagnetic part, i.e., a static position-dependent nonlinear relation between currents and forces, and the mechanical part, i.e., a dynamic relation from forces to position. Commutation inverts a model of the electromagnetic part of the system, and thereby removes the electromagnetic part from the position control problem. Typical commutation algorithms rely on simplified models derived from physics-based knowledge, which do not take into account position dependent parasitic effects. In turn, these commutation related model errors translate into position tracking errors, which limit the system performance. Therefore, in this work, we develop a data-driven approach to commutation using physics-guided neural networks (PGNNs). A novel PGNN model is proposed which structures neural networks (NNs) to learn specific motor dependent parasitic effects. The PGNN is used to identify a model of the electromagnetic part using force measurements, after which it is analytically inverted to obtain a PGNN-based commutation algorithm. Motivated by industrial applications, we develop an input transformation to deal with systems with fixed commutation, i.e., when the currents cannot be controlled. Real-life experiments on an industrial coreless linear motor (CLM) demonstrate a factor 10 improvement in the commutation error in driving direction and a factor 4 improvement in the position error with respect to classical commutation in terms of the mean--squared error (MSE).