(1) Data collection method
According to data collection vehicles, there are currently two main types of data acquisition methods.
The first category is to use a special data acquisition test vehicle, after installing all the test instruments, driving on a determined target road within a determined time, it is necessary to plan the test route and time.
The second category is to collect the actual vehicle directly on the target vehicle, that is, select the representative vehicle in use, install the test instrument, and drive the vehicle according to their normal purpose, and collect the required road condition data at the same time. This type of method has no regulations in terms of time and road, and is highly arbitrary. Its main advantage is that the vehicle is running under normal use and can obtain data on a large number of vehicle models with a relatively low investment. However, it cannot target certain road types, nor can it provide information about location, traffic flow, etc.
(2) Determination of test route and test time
If the above-mentioned type 2 method is used to collect data, there is no need to consider how to determine the route. If the above-mentioned type 1 data collection method is adopted, then the method of determining the route will be crucial. Route survey is the most basic stage of developing driving cycles, and its purpose is to screen out representative test routes from many roads. This kind of route collectively reflects the spatial and temporal distribution of the target vehicle on the road, so that a small amount of experimental data can be used to obtain statistical results that can represent global characteristics. Research shows that different road levels in a city correspond to different traffic flows and average speeds; on different road levels, the driving cycles of vehicles have different characteristics. In each road level, different traffic intensity must correspond to different driving cycles. Of course, it is possible to design 10 vehicles (or even more) to run simultaneously on non-repetitive roads in a certain area, collect enough samples to calculate the kinematics of the vehicles and their respective shares, but the implementation process requires a lot of manpower and material resources. . Based on the traffic flow theory (ν=KQ, where ν—vehicle speed, Q—vehicle flow, K—vehicle spacing), the traffic flow level and share of the corresponding route are obtained through traffic flow surveys. Under the premise of ignoring the time difference, a small number of vehicles can be used to run surveys on these routes to obtain vehicle operating data. This is a scientific, reasonable and easy-to-operate method. Vehicle driving cycles are mainly affected by road class (expressway, main road, secondary road, branch road and number of lanes, machine-non-mixing, etc.), traffic intensity (vehicle flow, turnover or saturation, etc.), intersection density (intersections within a section) Form and quantity) and the influence of the four major factors of time. Through investigation and collection of relevant data of traffic flow in a cycle in the urban area, statistical analysis is carried out. According to the statistical results of the data, the routes are divided into different categories, and then the probability sampling of the samples is carried out according to certain conditions, and the test route and test time are finally determined.
(3) Determination of test vehicle and driver
The test vehicle needs to determine three aspects: vehicle type, number and driver. With the first type of data collection method, the vehicle can be driven by a professional driver who often pays attention to the research target, or by an ordinary driver. But because it is often affected by preconceived “driving instructions”, it can’t actually be called a standard driving behavior. When a vehicle is driving on the road on its own (not deliberately overtaking or deterring), the operation of the vehicle will be mainly affected by the shifting strategy. Regardless of the technical level of the driver, its inherent driving behavior must be eliminated. With the increase of automatic transmission models, this and vehicles should be considered as the first choice. With the second method, there are more vehicles to choose from, and the vehicle type can be determined based on the popular models in the area (measured by market share)