Model-Free Adaptive PID Controllers Applied to the Benchmark PID'12

Many tuning strategies for PID control algorithms have been proposed in the literature depending on modeling choice from heuristics, physical laws and/or experimental essays. In this paper, the properties of three model-free adaptive PID control design conceptions, known as direct PID control, are investigated and implemented. The recursive least squares estimator is used to identify the PID controller gains without the knowledge of the plant mathematical model. The tuning strategies of the direct PID controller are applied to the boiler control system proposed by Fernando Morilla (UNED, Spain) as a benchmark problem for the 2012 IFAC Conference on Advances in PID Controllers.