Altitude Standardization Method to Improve Altitude Data Accuracy in On-road Driving

In a vehicle driving test, altitude data is used to determine elevation gain and calculate driving resistance. However, altitude data acquired from GPS has the disadvantage of low accuracy and missing data. This study proposed altitude standardization in order to increase the accuracy and interpolate the missing data. The altitude was recorded during 20 driving tests on the same route. All the data were accumulated based on latitude and longitude, and the missing data was interpolated by using the smoothing spline method. Positive cumulative elevation gain with high reliability was obtained by using only the altitude data from three driving tests. The accuracy of the standardized altitude was confirmed through driving resistance analysis. Meanwhile, driving resistance was used to calculate engine efficiency. The results showed that the engine efficiency calculated using the individual altitude was unrealistic, whereas the engine efficiency calculated using the standard altitude was constant at 35 %. This indicates that the standard altitude was correctly interpolated.