Secondary O2 Feedback Using Prediction and Identification Sliding Mode Control -Second Report- 2001-01-0264
The Honda Accord is the world's first automobile meeting the SULEV category criteria in the LEV-II exhaust emissions standards. An improved accuracy engine control system and catalyst account for the automobile's extremely low emissions. The accuracy engine control system includes double adaptive air-fuel ratio feedback loops composed of STR (Self-Tuning Regulator), for primary air-fuel ratio control, and PRISM (Prediction and Identification Sliding Mode Control), for secondary O2 feedback. The basic algorithm of the latter was presented at SAE 20001).
However, two issues required further PRISM algorithm improvements in order to apply the double adaptive loops to an actual vehicle. One such achievement is both the compensation for engine dynamic characteristics by PRISM and the avoidance of the reciprocal interference with two adaptive loops. Another improvement is the identification of an exact controlled object model that provides the same frequency characteristics as that of a controlled object from the UEGO sensor upstream of the catalyst to the HEGO sensor downstream.
Consequently, several algorithm improvements were introduced to the double adaptive loops discussed in this paper in order to resolve these issues.