Research On PID Parameter Tuning Of Aero-engine Actuator With Nonlinearities

PID control is one of the classical control strategies. Because of its simple algorithm, high reliability and good robustness, PID controllers are widely used in motion control and process control. However, the ideal linear system does not exist in real industry. The dynamic and static characteristics of the various components in the system, strictly speaking, exhibits different degrees of nonlinearity. And in actual system, a great deal of common non-linearity will have a bad effect on system performance. Therefore, it is of great significance and appli-cation value to determine the PID parameters of three-dimensional stability region with typi-cal segments of the nonlinear system, and find PID controller parameters meeting closed-loop control in the stability region by setting parameters,.This thesis focuses on two kinds of common typical nonlinearity in actual control sys-tem:saturation and dead-zone. This thesis studies and discusses how to determine the three dimensional stability region of PID parameters of system with typical nonlinear process. When the control system has a typical nonlinearity, by using the method describing function method, the nonlinear part of the system is represented by the describing function of N(A). A set of N(A) can be established by taking different value A. Based on the set of N(A), the non-linear system can be described as a linear system cluster.Then according to the inverse Ny-quist plot, by means of the Hermite-Biehler theorem and using "Counterclockwise" law, through intersecting the parameter stability region of the linear system cluster, the whole sta-bilizing region of PID controller parameters of the system with typical nonlinear segments is given.Introducing the stability performance index, based on the stability margin constraint, the whole stabilizing region of PID controller parameters with typical segments of the nonlinear system has been discussed in the frequency domain. By treating the amplitude constraint or the angle constraint as the proportional gain of the complex field, using the intersection ap-proach, the whole stabilizing region of PID controller parameters with typical segments of the nonlinear system is given. By using the simplex method and interior point penalty function method,optimal controller solution is obtained in the parameter stability region.. The simula- tion examples have proved the algorithm’s simplicity and effectiveness.