High Performance Idle Speed Control Applying the Sliding Mode Control with H^∞ Robust Hyper Plane

Abstract

The idle speed reduction is one of the important solutions for fuel economy improvement. And to achieve it, it is required to improve the performance of idle speed control to prevent from engine stall. We consider that the sliding mode control (SMC) representative in the nonlinear control theory is suitable for the idle speed control system. Because this system has non linearity like torque and friction characteristics. However it was said that it was difficult to get the high performance by SMC because of the chattering problem. In the previous paper, we described the following issues. The chattering problem comes from the large switching gain to attenuate the disturbance that does not satisfy the matching condition. However we could reduce the chattering of output (engine speed) by applying the acceleration reaching law and we could get the high performance superior to PID and LQG. In this paper, we describe the more effective way to reduce the chattering. That is, we applied the robust hyper plane that is frequency_shaped by H infinity control. And then we could succeed in reducing not only the chattering of output (engine speed) but also the chattering of control input while keeping the high performance.