Real-Time, On-Road Measurement of Driving Behavior, Engine Parameters and Exhaust Emissions 2002-01-1714

Automotive tailpipe emissions are a significant contribution to urban air quality problems.⁽¹⁾ However, it is difficult to quantify the extent of that contribution and to quantify any progress in solving the problem. Emissions inventories are commonly based on vehicle registrations, assumed mileage and a set of emission factors. The emission factors are based on dynamometer testing of selected vehicles undertightly controlled conditions. Actual vehicle operation in any urban area encompasses a wider range of vehicles, operating conditions and ambient conditions. Given the highly tuned nature of current engine management systems, the actual in-use emissions levels can be highly sensitive to non-standard ambient and operating situations.^(2,3,4,5)

This paper describes an on-board system used to record ambient conditions, driving behavior, vehicle operating parameters, fuel consumption and exhaust emissions. The system uses a laptop computer data acquisition system and a number of add-on sensors, (which include a five-gas analyzer and fast-response lambda sensor). Recorded data files are post-processed to measure values ranging from simple vehicle speed and distance traveled to emission rates in grams per kilometer. In addition, using the vehicle speed trace as input to a vehicle dynamic model the tractive power requirements could be calculated.

The paper presents results for a small set of repeated commuting trips to illustrate the capabilities and repeatability of the in-use measurement system. Also included are diagnosis of emission control system anomalies which significantly affected emissions but were not detectable by the driver.