Data-driven controller tuning using frequency domain specifications

This paper presents an overview of our recent work on a model-free proportional- integral - derivative (PID) controller tuning procedure. The method can handle different stability and performance indicators in the frequency domain. The phase margin, gain margin, crossover frequency, and more-advanced indicators, which are the infinity-norm of the sensitivity functions, can be considered for the design. The actual values of the design parameters are measured directly on the system, thanks to closed-loop experiments. A frequency criterion is then defined as the weighted sum of squared errors between the measured and desired values of the design parameters. The minimization is done iteratively using the Gauss-Newton algorithm. The approach presented does not require any parametric model of the plant and can be applied to a wide range of industrial applications. Simulation examples show the rapid convergence of the algorithm and the effectiveness of the method for PID controller tuning.