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.