Research On Driving Control And Fuel Saving Mechanism Of Commercial Vehicle Platoon

In recent years,with the rapid development of e-commerce and economy,China has become a tremendous logistics country,which has led to the rapid expansion of road transportation in China.The ever-growing road transportation has ensured the rapid expansion of our country’s economy,but road transportation still has problems that need to be solved urgently:(1)The shortage of commercial vehicle drivers;(2)Energy consumption;(3)Commercial vehicle traffic accidents.In order to solve the above-mentioned problems,the intelligentization of automobiles provides new solutions.As one of the solutions,commercial vehicle platooning has gradually become a research hotspot in recent years.Although the commercial vehicle platooning has significant advantages in energy saving and emission reduction,reducing traffic accidents and solving the shortage of drivers,there are still some problems in current research:(1)The current research on the spacing safety control of platoon is still imperfect.Especially when the leading vehicle performs emergency braking,the platoon is extremely prone to collisions due to communication delays,braking delays,and low adhesion roads caused by rain and snow;(2)The mainstream idea of commercial vehicle platooning at China and abroad is that the following vehicle is driven by the controller,and the leading vehicle is driven by human.However,the proportion of rollover accidents in commercial vehicle accidents is extremely high,and rollover accidents are mostly caused by improper operation of the driver.If the leading vehicle in the commercial vehicle platoon causes a rollover accident due to the driver’s improper operation,it can directly affect the safety of the following vehicle and bring a serious accident risk.Therefore,how to ensure that the leading vehicle does not roll over under manual driving is an important safety guarantee for platoon driving.However,few people in the current platoon research mentions the anti-rollover control of the leading vehicle in the commercial vehicle platoon;(3)At the same time,the current research to improve the fuel-saving effect of commercial vehicle platooning is mostly to reduce the vehicle spacing.This increases safety risks.Therefore,in order to optimize the fuel efficiency of the platoon,we should not only rely on reducing the vehicle spacing,but also consider other factors that affect the fuel consumption of the platoon.However,the current research on the factors that affect the fuel consumption of platooning(fuel-saving mechanism research)is imperfect or even lacking.In order to solve the above problems,relying on the science and technology project: Distributed Electric Vehicle Dynamic and Collaborative Control Based on Chassis-by-Wire System(JJKH20200963KJ),this paper makes the following work for the research of commercial vehicle platoon vehicle-following control,safety control and fuel-saving mechanism:(1)The vehicle longitudinal dynamic model of the following vehicle and the three degree of freedom roll model of the leading vehicle are established.In order to realize acceleration control and fuel consumption analysis of commercial vehicle,engine model,braking model and engine fuel consumption model are established.The stiffness of three degree of freedom roll model is calibrated.The simulations of double-shifting and sinusoidal conditions are carried out to confirm the precision of the three-degree-of-freedom roll model.The results indicated that the model simulation results are in better agreement with the Truck Sim simulation results.(2)Design of vehicle-following longitudinal controller for the following vehicle based on a hierarchical control system.The SMC vehicle-following model is designed based on the sliding mode control(Sliding Mode Control,SMC)principle,and the control effects of the SMC vehicle-following model and the Full Velocity Difference(FVD)vehicle-following model are compared by simulation.The results indicated that the SMC vehicle-following model is more effective.The lower controller designs the PID throttle controller and PID brake controller based on the inverse longitudinal dynamics model.To prevent frequent switching between acceleration and deceleration,throttle control and brake control switching function modules are added to the lower controller.In order to confirm the control effect and effectiveness of the established longitudinal controller for commercial vehicle platooning,the combined simulation of Truck Sim and Simulink is used to verify and analyze the control effect under different conditions of acceleration and deceleration cruise.The simulation results indicated that the designed controller can make commercial vehicles form a stable platoon in a variety of situations,and has good adaptability and followability.(3)Aiming at the longitudinal safety control,a spacing safety control strategy is adopted to prevent the collision of commercial vehicle platooning in case of emergency braking.The emergency braking MIL simulation is carried out under the two conditions of low adhesion road and different braking forces of member vehicles.The results indicated that the spacing safety control strategy adopted in this paper effectively prevents the collision between member vehicles.For the lateral safety control of the platoon,it is only necessary to ensure that the leading vehicle does not rollover under manual driving to ensure the lateral safety of the entire platoon.For the leading vehicle,the Kalman filter state estimator is designed based on the discretized three-degree-of-freedom roll model.Use this estimator to estimate the current vehicle state and predict the future load transfer rate changes to obtain the rollover time.Based on the rollover time,LQR control and PID control are designed to prevent rollover.The fishhook condition and j-turn condition show that the two algorithms can prevent rollover,but the LQR control has the best effect and high safety.(4)In order to improve the fuel-saving effect of commercial vehicle platooning,the current research mostly minimizes the vehicle spacing on the premise of ensuring safety.It is difficult to achieve both energy saving and safety by reducing the vehicle spacing,and it is not possible to reduce the vehicle spacing excessively while ignoring potential safety risks.Therefore,in order to optimize the fuel-saving effect of the platoon,we should not only rely on reducing the vehicle spacing,but also consider other factors that affect the fuel consumption of the platoon.Therefore,this paper studies the influence of a series of factors such as the number of vehicles,vehicle position at different loads(heterogeneous platoon),starting vehicle spacing and desired vehicle spacing on the fuel consumption of commercial vehicle platooning.