Economic Speed Planning for Commercial Vehicles on Highways

When the vehicle driving on the highway, the driver spontaneously conduct the friction brake to slow down the vehicle speed until reach the limit of the ramp speed after releasing the accelerator pedal. It is the unpredictably environmental conditions and the driver's limited sight distance that make unnecessary fuel consumption in the process of braking at the highway exit. This research is based on the road information of highway exit and the ramp limit speed provided by the Geographic Information System (GIS). The vehicle driving state is collected in real-time to estimate the parameters of car engine braking and air resistance characteristics. The early intervention of engine auxiliary braking is appropriately involved, which can be beneficial for reducing the engine fuel supply. Nine typical drivers were selected to take the test on the driving simulator. The test is that driving a commercial vehicle with unknown vehicle configuration on the highway exit road. The test results absolutely show that the vehicle parameters identification has great adaptability. The economic speed planning can improve the fuel economy by 1%. The economic speed planning system can be flexibly used in multiple driving systems and automatically adapt to the characteristic parameters of the vehicle type. This system has a promising and profitable prospect in improving the fuel economy of the commercial vehicle driving on the highway exit road.