Longitudinal road gradient estimation using vehicle CAN bus data

Knowledge of the longitudinal road gradient can be used by Advanced Cruise Control (ACC) and automatic transmission control systems to provide more accurate longitudinal velocity control. This paper presents a method of estimating the longitudinal road gradient just using the available vehicle CAN bus data. This method ensures that no extra sensors need to be added to the vehicle, and therefore there is no added cost to the vehicle. The gradient estimation algorithm is developed combining vehicle modelling techniques and parameter estimation methods. A simple longitudinal acceleration vehicle model is derived using standard vehicle model equations. The unknown longitudinal gradient parameter is then estimated using the data available on the CAN bus.