Automatic Tuning of Two-Degree-of-Freedom PID Control for Engine Electronic Throttle System

Engine Electronic Throttle Control (ETC) systems are gaining success in high volume applications. This system helps to improve overall engine and vehicle performance, as well as facilitate the function integration of related control features. The requirement for an ETC system is that it fulfills the commanded throttle plate opening as quickly and accurately as possible. Because of nonlinearity of the electronic throttle system, gain-scheduled control is often used. A method to automatically tune the control for each operating region is needed. In this paper the engine electronic throttle is considered as having dominant linear dynamics for each operating region. A Two-Degree-of-Freedom (2-DOF) PID controller and a method of using Model Reference Adaptive Control (MRAC) algorithm to automatically tune the PID control gains are designed. With this approach, control performance enhancement from initial control settings can be realized with closed loop testing, without the need of a plant model. Control gains that give good performance can be obtained quickly for each operating region of the system. The designed control and automatic tuning algorithm is implemented on a rapid prototyping setup and the application results show the effectiveness of the method.