| In the era of reducing energy consumption and environmental protection,intelligent assisted driving system has become an important means and necessary way to achieve the goal of "Carbon Peak" and "Carbon Neutrality".As one of the assisted driving systems for commercial vehicles,the cruise control mainly focuses on safety and comfort,however,the terrain in China is mostly mountainous and hilly,and the undulating roads inevitably lead to the increase of fuel consumption of vehicles.In this paper,we propose a road-adaptive cruise control system that realizes automatic control of vehicle longitudinal direction with the help of road slope information to reduce fuel consumption,in view of the insufficient fuel-saving ability of fixed-speed cruise control under ramp conditions.The main research contents are as follows:(1)In order to meet the demand of road-adaptive cruise control system,under the framework of model prediction "control rolling time domain optimization",the marginal value transformation and generalized minimal residual optimal control solution method of the minimal value principle are introduced,the overall control scheme of the adaptive cruise control system is proposed for the purpose of energy saving,and the hierarchical control structure of the road adaptive cruise control system is designed.(2)According to the requirements of the road adaptive cruise control system on fuel consumption model,in order to make up for the insufficient prediction effect of the existing developed fuel consumption model,this paper establishes a polynomial fuel consumption model with "steady-state initial estimation + transient correction" based on the fuel consumption data of the real vehicle through the actual road,forming a fuel consumption model with simple structure,meeting the special working conditions and high prediction accuracy.In order to ensure the road-adaptive cruise control system,the fuel consumption model of the road-adaptive cruise control system is developed.(3)To ensure that the road-adaptive cruise control system effectively controls the longitudinal motion of the vehicle,the digital map resolution method and the vehicle longitudinal dynamics model are established and the upper control system uses the discrete nonlinear model of the minimal value principle to predict the covariance of the control,and the generalized minimal residual numerical algorithm solves the control margins differentially,and the solution equations based on the optimal variables of the cruise control are transformed to solve the control sequence and the state sequence under the optimal state,so as to obtain the road slope ahead,state sequences to obtain the optimal control sequence for the longitudinal demand torque of the road slope ahead.The lower control system outputs the desired throttle opening based on the inverse longitudinal dynamics model of the vehicle,and the controller controls the vehicle in real time so as to improve the fuel economy of the vehicle.(4)To verify the fuel saving effect of the road-adaptive cruise control system for logistics commercial vehicles,the proposed road-adaptive cruise control system is jointly simulated and verified based on Matlab/Simulink and Truck Sim in different road conditions in this paper.The results show that compared with the fixed-speed cruise control,the average fuel saving effect of the proposed road-adaptive cruise control system reaches about 3%,which provides the theoretical support for the development of energy-saving road-adaptive cruise control system for logistics commercial vehicles. |
