Contouring Error Bounded Control for Biaxial Systems with Structural Flexibility and Input Delay

TL;DR

This paper introduces a model predictive control strategy for biaxial systems with flexibility and input delay, ensuring accurate contouring within error bounds in machining applications.

Contribution

It develops a robust control method that explicitly considers input delays and mechanical vibrations, applicable to arbitrary contour shapes in industrial machining.

Findings

Achieves bounded contouring error in experimental tests.

Handles input delays and mechanical vibrations effectively.

Demonstrates low commissioning effort for practical implementation.

Abstract

Precision contouring control is crucial in industrial machining processes, particularly for applications such as laser and water jet cutting, where contouring accuracy directly determines product quality. This paper presents a novel control strategy for biaxial machines featuring position-dependent flexibility and input delays, ensuring that the end-effector accurately traverses the desired contour within specified contouring error bounds and system constraints. To capture the rotation dynamics for systems with mechanical vibration, we introduce a high-fidelity model and explicitly consider the input delay with augmented system states. The controller design is based on the model predictive control scheme to enforce system states staying in robust control invariant sets defined by the reference model and switched linear time-invariant control-oriented models. The proposed algorithm is not restricted to a specific shape of the curve that is being traversed. The effectiveness of the proposed control algorithm is demonstrated in an experimental environment with discretizations and input delay. The results show that a bounded contouring error can be achieved by the proposed method in a performance degradation environment with a low commissioning effort.