Robust H∞-Optimal PI Cascade Control for Servo Drive Applications Solved by a Genetic Algorithm

Controlling a multi-mass system is a common problem in industrial automation. Varying or even unknown parameters cause the difficulty of the control. A powerful tool in order to control systems with uncertain parameters is a robust H∞-control. Unfortunately the complex structure and the mathematical theory prevent known H∞ controllers from the usage in many industrial applications. In this work the design of a robust control for a two-mass system will be described. In many cases a two-mass system is a sufficient model for the controller synthesis because it includes the lowest resonance case. The structure of the controller is a common structure of a popular PI/P cascade control. However, the desired parameters of the robust cascade control are calculated by a genetic algorithm with respect to the H∞-Norm. Measurements will complete the paper.