Research On Eco-Driving Of Connected Autonomous Plug-in Hybrid Electric Vehicle In Complex Traffic Conditions

Plug-in hybrid electric vehicle(PHEV),integrating the virtues of electric vehicles(EVs)and hybrid electric vehicles(HEVs),is a desirable solution to support long driving mileage and meanwhile promote energy consumption economy.Nowadays,thanks to the enormous breakthroughs in wireless communication and intelligent sense technologies,traditional PHEVs gradually possess intelligent networking capabilities,with efficient environment sensing and decision-making abilities.The eco-driving control based on velocity planning and powertrain energy distribution optimization is one of the key technologies of connected autonomous PHEVs.In this paper,the research on eco-driving control of the connected autonomous PHEV in complex traffic conditions is carried out,with the core target of optimizing the vehicle economy,safety and comfort.The details of the paper are as follows:1)The internal logic and mutual relationship of the two core research focuses of passive vehicle-following and active vehicle platoon planning are clarified.The intelligent traffic environment for eco-driving control is designed,and the studied power-split PHEV powertrain structure and its power flow relationship are analyzed and modelled.The research goal of energy-saving,safe,comfortable and efficient vehicle driving is defined.2)The hierarchical predictive eco-driving control strategy of PHEV under passive vehicle-following scenario on urban roads is investigated.Firstly,the external traffic disturbance and PHEV powertrain characteristics are integrated into velocity planning via a Gaussian process(GP)model and a desired acceleration respectively in the upper layer;On this basis,in the power allocation layer,a double delayed Q-learning(DDQL)algorithm is employed to instantaneously optimize the power allocation for powertrain system.The simulation results demonstrate that the integration of traffic lights,powertrain characteristics and speed prediction of preceding vehicle into velocity planning of PHEV can make its velocity smoother,hence effectively ensuring the vehicle driving comfort and safety,meanwhile promoting the traffic efficiency.Moreover,the proposed eco-driving strategy can reach quasi-globally optimal energy economy of PHEV in a real-time manner.3)A learning-based control method,adaptive dynamic programming(ADP),is designed to simultaneously optimize the longitudinal traction force and powertrain energy management of PHEV under vehicle-following scenario,thereby further achieving the coupling optimization of velocity planning and powertrain energy management,meanwhile promoting the eco-driving control effect.The simulations demonstrate the developed ADP presents satisfactory online learning speed to efficiently conduct joint optimization of driving comfort,safety,and fuel economy of PHEV.The comparative studies for different velocity trajectories highlight the control performance of ADP in guaranteeing smooth and stable vehicle driving.Meanwhile,the developed strategy can reach quasi-global energy economy optimality of PHEV under urban and mixed driving conditions.4)A cooperative eco-driving control for connected autonomous PHEV platoon is developed,so as to achieve safe,energy-saving,efficient and comfortable driving of multiple PHEVs.Firstly,the velocity trajectory of leading vehicle at each isolated signalized intersection is planned using the pseudo-spectral method;On this basis,the cooperative optimization of following vehicles in the platoon is conducted under the rolling optimization framework,with the aim of improving driving comfort,safety and energy economy of the whole vehicle platoon.The simulation results highlight that the proposed cooperative eco-driving strategy can lead to preferable vehicle-following behaviors and multi-vehicle cooperative driving performance.As compared with that under manual driving,the overall energy consumption and trip time of vehicle platoon are remarkably optimized.Furthermore,as compared with that under the traditional platoon control strategies,the overall energy economy of PHEVs is significantly promoted.