Study On Optimal Eco-driving Of Urban Public Transport Vehicles

Eco-driving of public transport is a bus driving concept, which means to constrain the driving behavior, control the traffic dynamics of the public transport vehicles, ensure the vehicle as gentle as possible, and reduce the level of vehicle exhaust emission. As an important part of urban traffic, public transport system has a high level of exhaust emissions. It is of great practical significance to explore the optimal ecological driving problem of urban public transport vehicles, which is helpful to reduce the level of public transport. It is difficult to take into account the traffic demand of urban road network by controlling traffic environment with traditional method. With the aid of V2 I communication technology, it is better to obtain and update the traffic information in a timely manner and has the advantages of high real-time performance, good control effect and so on. This paper discusses the problem of optimal eco-driving for urban public transport vehicles from the viewpoint of controlling the vehicle dynamic adaptation to the traffic environment. That is to obtain the traffic information from the V2 I bus, according to the real-time traffic information to solve the optimal control scheme, control the vehicle's own driving dynamics, adapt to changes in the road traffic disturbance, and reduce the exhaust emissions of public transport vehicles.Firstly, build the eco-driving model for urban public transport vehicle. The hybrid dynamic model of public transport vehicles, the model of the intersection signal lamp timing scheme, the bus stop delay model and the vehicle emission model are abstracted from the actual operating conditions of urban public transport vehicles. Vehicle's hybrid dynamic is the research object, considering the bus lane speed limit, through intersection with green light and other constraints, vehicle emission is selected as the evaluation index, build the eco-driving model for urban public transport vehicle. Establish a stop delay model containing the hysteresis strategy, after the passengers getting on and off the bus, the bus can choose to have additional residence time in the platform. The eco-driving model of urban public transport vehicles which contains the hysteresis strategy is established.Secondly, solve the optimal control scheme. Eco-driving of urban public transit vehicle is a high order hybrid nonlinear system with multiple constraints. By using the space position discretization, the discretization of the corresponding time domain and the model reduction are used to solve the optimization problem. The bus route is discretized by the platform position space, and the adjacent stations are a sub section, which is composed of several sub sections. By using the space rolling control method, the optimal solution of the corresponding reduced order model is solved step by step, and the optimal control scheme is obtained. Solving the optimal solution of the reduced order model, by the constraint conditions to determine the state variable feasible solution region, find a feasible path in the feasible solution region, find the optimal path in the feasible path.Thirdly, the experiment verifies the feasibility of eco-driving model for urban public transport vehicles and the optimal control scheme. To obtain the actual operation of Beijing city bus line form Baidu map and determine the parameters needed for the model, solving the model to observe and analyze the simulation diagram of experiment, validate the model and the control algorithm is feasible.Finally, design the bus driver APP, to realize the information interaction between the driver and the optimal driving scheme. Driver APP design includes bus positioning, communication and the optimal driving scheme shows three modules. Select mobile GPS positioning module positioning bus vehicle; using HTTP communication protocol and the background of the server communication, and access to the online optimal control scheme; the optimal driving scheme includes the arrival of the prompt, the vehicle starts, and the front intersection tips three major categories of information. The establishment of local offline database, using the local database to verify the APP positioning function, vehicle real-time position display function and the optimal driving scheme tips.