Monday, August 22, 2016

Korean study demonstrates 100% wide open throttle SUA reproduced by auto voltage drop

A very odd couple: Gas pedal, 35%, throttle valve 100%

 S. Park, Y. Choi, W. Choi, Experimental Study for the Reproduction of Sudden Unintended Acceleration Incidents, Forensic Science International (2016),
A few cases of the sudden unintended acceleration have been reported over the last few years 0005, 0010, 0015, 0020, 0025, 0030, 0035, 0040, 0045, 0050 and 0055 and some of them seemed to be somewhat related to an electronic throttle control (ETC) system 0055 and 0060. In this experimental study, efforts were made to reproduce the cases of sudden unintended acceleration possibly related to the ETC. Typically, an ETC of the engine is managed based on signals from airflow sensor, throttle position sensor and acceleration pedal sensor. With this typical sensor configurations in mind, these sensor signals were checked for noise levels. However, none of them showed any clear relationship with the sudden unintended acceleration mainly due to the robustness of the ETC logic software. As an alternative approach, supply voltage to an engine control unit (ECU) was tempered intentionally to observe any clues for the incidents. The observed results with the supply voltage drop and fluctuation tests were rather astonishing. The throttle valve position went all the way up to 100% for around one second when the battery voltage plunged down to 7 V periodically despite that the acceleration pedal position was kept steady. As an effort to confirm the case, multiple tries were made systematically on a chassis dynamometer as well as on the test road. In this paper, detailed procedures and findings are reported accordingly.

Question: The authors point to vehicles overloaded with power-hungry electrical devices as a likely cause of low voltages and SUA. In at least a dozen documents, including one that I posted here a few days ago, Toyota engineers expressed concerns that vehicles were behaving unpredictably due to issues with electrical loads. What is the connection?