Research On Economic Cruise Control Of Vehicle Based On Instantaneous Fuel Consumption

With the rapid increase of global automobile ownership ratio,the amounting energy consumption of automobiles brings great pressure to such natural resources as petroleum.It is thereby imperative to improve the fuel efficiency of automobiles and develop energysaving automobile technologies.In fact,the fuel economy of a vehicle is generally affected by the state of the vehicle,drivers’ behaviors and traffic conditions.When vehicles drive on urban roads,frequent emergent operations such as acceleration,deceleration and long-term idling(waiting for traffic lights)often result in an increase in fuel consumption.Economical driving can improve the economy of a vehicle by improving the driver’s decision and operation of throttle,brake,and shift.With the development of Adaptive Cruise Control(ACC)system,the automatic Control system can completely replace the driver for economical driving and then achieve the purpose of saving fuel.Therefore,based on the adaptive cruise control,this paper introduces the transient fuel consumption model of vehicles and economical driving strategy to study economical cruise control,so as to improve the fuel economy of vehicles.The specific research contents are as follows:1 Vehicle fuel consumption model based on transient variable polynomialIn this study,based on the fuel consumption data of a passenger car,a uniform expression of the polynomial transient fuel consumption model is proposed,and the accuracy and fitness of the existing fuel consumption models are analyzed.The BIC(Bayesian Information Criterion)information criterion is introduced as the evaluation standard for the fuel consumption model.Then,a polynomial-based transient fuel consumption model with simple structure and high precision is established to compare with the existing transient fuel consumption models.2 Economical speed planning based on transient fuel consumptionOn the basis of the fuel consumption model,the economical speed planning is carried out in road sections and intersections to determine the ideal method for the economical speed planning when in acceleration and deceleration motion and at uniform speed as well.At intersections,combined with Vehicle to Infrastructure communication technology V2I(Vehicle to Infrastructure),an intersection-condition prediction model considering traffic light information is established.The trigonometric function strategy and the constant acceleration strategy are used to plan the vehicle speed at the intersection,and hence the fuel-saving law of the vehicle passing through the intersection is obtained,which helps simplify the optimization variable in the vehicle speed planning.Meanwhile,the economical speed planning strategy of constant acceleration and that of trigonometric function are compared and analyzed.3 The overall structure and mode switching strategy of economical cruise controlBased on the vehicle spacing model,the state equations of the longitudinal dynamics model were derived under two conditions when there are vehicles running within the reaction distance and when there are not.Two basic modes of economic cruise controller,speed following and vehicle following,are proposed.Considering the model-switching impact,a controller’s transition mode is also added to the overall structure of the economical cruise control in order to improve the comfort in switching modes.Then,the mode-switching strategy models for speed following,vehicle following and the transition state are established in Simulink/Stateflow.4 Design of the controller layer in economical cruise systemAfter the upper and lower controllers of the economical cruise control system are designed by using the hierarchical control framework in this study,the driving and braking system models are established,and the PID controller with feedforward and feedback is designed to verify the tracking effect of the controller under typical working conditions.With the Model Predictive Control algorithm(MPC),the upper controller is designed based on the distance dynamics model to study the influence of different weight coefficients on the control performance of the cruise system under the following conditions.In this way,the weight coefficients of three following modes,namely,ordinary following MPC_N,economical following MPC_E and tracking following MPC_T,are obtained.Finally,the mode-switching strategy of economical cruise control system is verified and analyzed by comparing it with Linear Quadratic Regulator(LQR)control algorithm.