Abstract:

A differential algorithm was developed without using any inertial measurement unit, to calculate the acceleration of autonomous vehicles, and to reduce the test cost with a rational calculation accuracy. The calculation error was analyzed to contrast three algorithms, which had the fixed step-size, or the mean fixed step-size, or the variable step-size. The calculation results were compared with the measured accelerations in real car. The result shows that a suitable step-size improves the calculation accuracy; The calculation accuracies of the algorithms with 0.2-s or 0.3-s step-size are better than that of the algorithms with other step-sizes when using fixed step-size; The fluctuation of the calculation results by using the mean fixed step-size is smaller than that with the fixed step-size when the step-size is the same; The maximum absolute errors is 0.77 m/s² for the fixed step-size algorithm, with being 0.64 m/s² for the mean fixed step-size algorithm, and with being 0.46 m/s² for the variable step-size algorithm; The average absolute errors are 93, 82, and 65 mm/s² respectively for the fixed step-size algorithm, the mean fixed step-size algorithm and the variable step-size algorithm. Therefore, the calculation accuracy by using the variable step-size algorithm is the best among the three algorithms.

Key words: autonomous vehicle tests, accelerations, variable step-sizes, differential algorithms, calculation accuracy