A Verification Study for Cam Phaser Position Control using Robust Engineering Techniques

This paper describes the verification and comparison of position control algorithms for a continuously-variable cam phaser. Robust Engineering techniques are used. Two non-linear PID control algorithms are designed to control cam phaser position. The first algorithm is a more complex control strategy while the second is a thrifted approach that seeks to reduce throughput requirements. An L₁₈ orthogonal array is established with noise factors that affect the quality of cam phaser control. Using the orthogonal array, the number of experiment test points required to characterize the control algorithm response is reduced from 8,748 to thirty-six. The test points of the orthogonal array are investigated experimentally on a motored engine outfitted with cam phaser hardware. The desired and actual cam position data are compared and analyzed for all points in the orthogonal array. Both control algorithms result in similar signal to noise ratios for the bench testing, showing the thrifted control algorithm to perform similarly overall. A final verification of the control algorithms is performed on a vehicle with a complete engine management system. The more complex control algorithm is shown to yield superior performance in the vehicle-level evaluation.