Development, Comparison and Application of Various Parameter-Adaptive Digital Control Algorithms

Abstract

Various recursive parameter estimation algorithms and controller design procedures can be combined to build up parameter adaptive control algorithms. Three parameter estimators and seven control algorithms have been selected taking into account good convergence properties and small computational expense and regarding the conditions for closed loop identification. The resulting 21 adaptive control algorithms are compared and tested with a process computer in on-line operation with analog simulated stable and unstable processes for stochastic and deterministic disturbances without and with external perturbation signals. The results are very promising. In many cases a good control performance is achieved. As a priori knowledge only the sampling time, the process model order and time delay and in some cases a weighting factor for the process input signal are required.The best adaptive control algorithms are applied for digital adaptive control of a nonlinear pipeline pilot plant and an air heater. Conclusions are given for the selection of parameter adaptive control algorithms, depending on the type of process and its disturbances.The adaptive control algorithms can be applied for adaptive control of constant and time variant, linear and nonlinear, stable and unstable processes with process computers or micro computers or for self-tuning of control algorithms or tuning of conventional analog PID controllers.