Diagnostics for automotive electronic throttle body systems

If not properly diagnosed and corrected, temperature and position varying characteristics of friction observed in production automotive electronic throttle body (ETB) systems can lead to performance degradation, increasing warranty cost for automotive manufacturers. Consequently, friction diagnostics for ETBs has become an important issue for OEMs and ETB manufacturers. However, relatively little attention has been given to the issues of friction diagnostics for such systems. In this research, preliminary studies are presented for this problem via a mathematical formulation, thereby mitigating measurement and computation limitations in production hardware. A friction estimation scheme based on the principle of sliding modes is demonstrated in simulation for a typical production ETB. The contributions of this work lie in the friction modeling methodologies (incorporating experience in ETB operation) as applied to production ETB systems, and the novel control-theoretic approach for attaining useful diagnostic information.