Dynamometer Load Reduction for Low Power Vehicles Driving the US06 Supplemental Federal Test Procedure 980405

This report summarizes the development work for the US06 Low Power Vehicle Adjustment (LPVA) algorithm for the Supplemental Federal Test Procedure (SFTP). The algorithm is integrated into the control software of a 48 inch (1219 mm) single roll electric dynamometer, and temporarily assists vehicles by reducing the road load. To qualify for assistance, vehicles must accumulate 7 seconds of wide-open-throttle (WOT) within any of five prescribed windows of time during the US06 test. WOT is defined as 85-100% of the vehicle's throttle position sensor (TPS) output. The assistance continues until the TPS signal falls below the 85% criterion. The assistance typically lasts 1 second before WOT is relieved and yields approximately 8 seconds of total WOT condition.

The LPVA algorithm has been successfully tested on a number of vehicles with a range of data acquisition rates. The LPVA algorithm, when activated, decreases the time at WOT for a low power vehicle and allows the vehicle to return to the drive trace. The design criteria of 8-second WOT, 85% TPS, and five prescribed acceleration windows were included in the Environmental Protection Agency (EPA) SFTP Final Rulemaking [1].