Intelligence analysis and improvement of nonlinear PID based on nonlinear norm transformation

Nonlinear proportional-integral-derivative (NPID) controller is realized by modulating the control gains of a conventional linear PID controller. In order to develop the machine intelligence, the intelligence and modulating principles of P-I-D controls of NPID controller based on nonlinear norm transformation (NNTPID for short) are discussed in This work. A revision is proposed to the integral control of NNTPID and simulation results show that the improved NNTPID can accelerate the stabilizing process and reduce rising time and overshoot. As for the disadvantage of the steady output errors caused by the simulation precision or the sensitivity of measurement instruments in practical applications, a variable structure control or multimodal control strategy is also suggested.