Scanning parameters optimization for digital PI controller

In this paper, scanning parameters optimization (SPO), a new method for parameters tuning of digital proportional-integral (PI) controller is proposed. It can automatically search for the optimal parameter group which contains both proportional action coefficient and integral action coefficient that fits the user´s design from a set of candidate groups by scanning their performance indices, such as rise time, overshot and steady state error. Satisfactory degree function (SDF) and automatic rules generating algorithm (ARGA) are developed within this method to make the three indices which have different dimensions mapped into a cost function. With grain analysis algorithm (GAA) we can get the optimal parameter group last. The major two advantages of this method are that it can present an overview of the parameter groups without knowing the plant model of the target system and provide a result of overall optimization. Its application in the control system of atomic force microscopy (AFM) in our lab shows that it is practical and has excellent performance.