Vehicle dynamics modeling method based on Carsim

Abstract

The invention provides a Carsim-based vehicle dynamics modeling method, and belongs to the technical field of vehicle simulation testing, and the method comprises the steps: building a vehicle body parameter model of a simulation vehicle, building an aerodynamic model of the simulation vehicle, building a power and transmission system model of the simulation vehicle, and building a braking system model of the simulation vehicle; establishing a steering system model of the simulation vehicle, establishing a tire model of the simulation vehicle, and establishing a dynamic model of the simulation vehicle based on the vehicle body parameter model, the aerodynamic model, the power and transmission system model, the braking system model, the steering system model and the tire model; according to the method, acceleration, braking and steering sent by a simulation system control algorithm are responded, a target vehicle can be restored, the precision of a simulation model is ensured, meanwhile, the dynamic response of a real vehicle body of the target vehicle is simulated, and therefore the simulation test requirement of the automatic driving function is met.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle simulation testing, and more specifically, relates to a vehicle dynamics modeling method based on Carsim. Background Art

[0002] With the rise of autonomous driving technology, autonomous driving systems are growing explosively. To ensure system safety, testing and verification of autonomous driving has become an important problem. At present, due to the high cost of real vehicle testing, the proportion of simulation testing is gradually increasing. As one of the key factors in the confidence of the simulation system, the modeling accuracy and accuracy of the vehicle dynamics model affect the test results of the autonomous driving system. The vehicle dynamics model needs to respond to the acceleration, braking, and steering issued by the simulation system control algorithm, and at the same time simulate the dynamic response of the target vehicle's real body to support the testing of the autonomous driving system. The existing technology cannot take into account the above conditions, and the vehicle dynamics model has low accuracy. Summary of the invention

[0003] The purpose of the present invention is to provide a vehicle dynamics modeling method based on Carsim to solve the problem of low accuracy of vehicle dynamics models in the prior art.

[0004] In order to achieve the above object, the present invention provides a vehicle dynamics modeling method based on Carsim, comprising:

[0005] Based on the real appearance size parameters of the target vehicle, a body parameter model of the simulated vehicle is established;

[0006] Based on the real aerodynamic parameters of the target vehicle, an aerodynamic model of the simulated vehicle is established;

[0007] Based on the real power and transmission system parameters of the target vehicle, establish the power and transmission system model of the simulated vehicle;

[0008] Based on the real braking system parameters of the target vehicle, a braking system model of the simulated vehicle is established;

[0009] Based on the real steering system parameters of the target vehicle, a steering system model of the simulated vehicle is established;

[0010] Based on the real tire test data of the target vehicle, a tire model of the simulation vehicle is established;

[0011] A dynamic model of the simulated vehicle is established based on the vehicle body parameter model, aerodynamic model, power and transmission system model, braking system model, steering system model and tire model.

[0012] Optionally, the actual appearance size parameters of the target vehicle include:

[0013] The target vehicle's body length, body width, body height, vehicle mass, sprung mass, left front unsprung mass, right front unsprung mass, left rear unsprung mass, right rear unsprung mass, roll moment of inertia, pitch moment of inertia, yaw moment of inertia, longitudinal distance from the center of mass to the front axle, longitudinal distance from the center of mass to the rear axle, vertical height from the center of mass to the ground, front axle load, rear axle load, sprung mass, front axle unsprung mass, rear axle unsprung mass, and loaded mass.

[0014] Optionally,

[0015] The aerodynamic model of the simulated vehicle is established including:

[0016] Selecting an aerodynamic reference point of an aerodynamic model of a simulated vehicle;

[0017] Calculate the frontal area parameters of the aerodynamic model of the simulated vehicle;

[0018] Calculate air density parameters of the aerodynamic model of the simulated vehicle;

[0019] An aerodynamic model of a simulated vehicle is obtained based on an aerodynamic reference point, a frontal area parameter and an air density parameter;

[0020] The actual aerodynamic parameters of the target vehicle include:

[0021] The relationship curves between the target vehicle’s drag coefficient, lateral force coefficient, lift coefficient and wind direction, and the relationship curves between the rolling moment coefficient, pitching moment coefficient, yaw moment coefficient and wind direction.

[0022] Optionally, a projection point on the ground of a midpoint of a line connecting a front axle center and a rear axle center of the simulated vehicle is selected as the aerodynamic reference point.

[0023] Optionally, the frontal area parameter is calculated based on a real appearance size parameter of the target vehicle and a ground clearance of the target vehicle.

[0024] Optionally, the air density parameter is 1.202 kg / m 3 .

[0025] Optionally,

[0026] The establishment of the power and transmission system model of the simulated vehicle includes:

[0027] Select the pure electric vehicle reference model in Carsim;

[0028] The real braking system parameters of the target vehicle are used to adjust the reference model of the pure electric vehicle to obtain the power and transmission system model of the simulated vehicle;

[0029] The actual braking system parameters of the target vehicle include:

[0030] A curve of the relationship between the speed and torque of the power motor of the target vehicle, wherein the curve is obtained by fitting the peak speed and peak torque of the target vehicle;

[0031] Equivalent moment of inertia, damping and stiffness of the transmission of the final reducer and differential.

[0032] Optionally,

[0033] The brake system model of the simulated vehicle is established including:

[0034] Select the hydraulic brake system model in Carsim;

[0035] The hydraulic brake system model is adjusted using the real brake system parameters of the target vehicle to obtain the brake system model of the simulated vehicle;

[0036] The braking system parameters of the target vehicle include:

[0037] The relationship between the target vehicle's front and rear axle brake input pressure and braking torque, the braking delay time, the longitudinal slip rate threshold for ABS device opening / closing, the minimum operating speed of the ABS device, and the ratio of the front and rear wheel transmission pressure to the pipeline pressure.

[0038] Optionally, the steering system parameters of the target vehicle include:

[0039] The relationship between the moment of inertia of the steering column, the moment of inertia of the steering system, the damping characteristics of the steering column, the hysteresis torque of the steering column, the reference hysteresis angle of the steering column, the lateral offset of the kingpin axis, the kingpin inclination angle, the X-coordinate of the center of the kingpin axis, the kingpin caster angle, the steering gear type, whether it has power assistance, the steering gear transmission ratio, the C characteristic of the steering system, the speed-sensitive ground friction steering torque, the power steering system, the power assistance torque, the power assistance speed, and the torsion bar torque.

[0040] Optionally,

[0041] The tire model of the simulated vehicle is established including:

[0042] Use the internal tire model in Carsim or the Pacejka5.2 tire model;

[0043] The internal tire model or the Pacejka5.2 tire model is adjusted using the real tire test data of the target vehicle to obtain the tire model of the simulated vehicle;

[0044] The tire test data of the target vehicle includes:

[0045] The effective rolling radius of the tire, the free radius of the tire, the vertical stiffness of the tire, the vertical maximum load, the wheel rolling resistance coefficient, the tire width, the tire moment of inertia, the longitudinal slack length of the tire, the lateral slack length of the tire and the speed threshold that has no effect on the lateral slack length of the tire.

[0046] The beneficial effects of the present invention are: providing a vehicle dynamics modeling method based on Carsim, including establishing a body parameter model of a simulated vehicle, establishing an aerodynamic model of a simulated vehicle, establishing a power and transmission system model of a simulated vehicle, and establishing a braking system model of a simulated vehicle; establishing a steering system model of a simulated vehicle, establishing a tire model of a simulated vehicle, and establishing a dynamic model of the simulated vehicle based on the body parameter model, aerodynamic model, power and transmission system model, braking system model, steering system model and tire model, so as to respond to acceleration, braking and steering issued by the simulation system control algorithm, restore the target vehicle, ensure the accuracy of the simulation model, and simulate the dynamic response of the real body of the target vehicle, thereby meeting the simulation test requirements of the automatic driving function.

[0047] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0049] Figure 1 A flow chart of a vehicle dynamics modeling method based on Carsim according to an embodiment of the present invention is shown.

[0050] Figure 2 A schematic diagram of the power transmission structure of a pure electric vehicle reference model in Carsim according to an embodiment of the present invention is shown.

[0051] Figure 3 A schematic diagram of the braking process of a hydraulic brake system model in Carsim according to an embodiment of the present invention is shown.

[0052] Figure 4 A schematic diagram of kingpin geometry parameters in Carsim according to an embodiment of the present invention is shown.

[0053] Figure 5a A lateral displacement-time relationship curve diagram of a simulation test result according to an embodiment of the present invention is shown.

[0054] Figure 5bA lateral acceleration-time relationship curve diagram showing simulation test results according to an embodiment of the present invention.

[0055] Figure 5c A roll angle-time relationship curve diagram showing simulation test results according to an embodiment of the present invention.

[0056] Figure 5d A yaw rate-time relationship curve diagram showing simulation test results according to an embodiment of the present invention.

[0057] Figure 5e A curve diagram showing the relationship between sideslip angle and time of a simulation test result according to an embodiment of the present invention is shown.

[0058] Figure 5f A graph showing the relationship between steering wheel angle and time showing simulation test results according to an embodiment of the present invention. DETAILED DESCRIPTION

[0059] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0060] Embodiment 1:

[0061] See also Figure 1 The present disclosure provides a vehicle dynamics modeling method based on Carsim, including:

[0062] Based on the real appearance size parameters of the target vehicle, a body parameter model of the simulated vehicle is established;

[0063] Based on the real aerodynamic parameters of the target vehicle, an aerodynamic model of the simulated vehicle is established;

[0064] Based on the real power and transmission system parameters of the target vehicle, establish the power and transmission system model of the simulated vehicle;

[0065] Based on the real braking system parameters of the target vehicle, a braking system model of the simulated vehicle is established;

[0066] Based on the real steering system parameters of the target vehicle, a steering system model of the simulated vehicle is established;

[0067] Based on the real tire test data of the target vehicle, a tire model of the simulation vehicle is established;

[0068] A dynamic model of the simulated vehicle is established based on the vehicle body parameter model, aerodynamic model, power and transmission system model, braking system model, steering system model and tire model.

[0069] Specifically, the dynamic model of the simulated vehicle is obtained based on the body parameter model, aerodynamic model, power and transmission system model, braking system model, steering system model and tire model, so as to respond to the acceleration, braking and steering issued by the simulation system control algorithm, restore the vehicle model, ensure the accuracy of the simulation model, and simulate the dynamic response of the real body of the target vehicle, thereby meeting the simulation test requirements of the autonomous driving function.

[0070] Optionally, the actual appearance size parameters of the target vehicle include:

[0071] The target vehicle's body length, body width, body height, vehicle mass, sprung mass, left front unsprung mass, right front unsprung mass, left rear unsprung mass, right rear unsprung mass, roll moment of inertia, pitch moment of inertia, yaw moment of inertia, longitudinal distance from the center of mass to the front axle, longitudinal distance from the center of mass to the rear axle, vertical height from the center of mass to the ground, front axle load, rear axle load, sprung mass, front axle unsprung mass, rear axle unsprung mass, and loaded mass.

[0072] Specifically, the above parameters are assigned to the corresponding parameter interface in Carsim to obtain the vehicle body parameter model.

[0073] Optionally,

[0074] The aerodynamic model of the simulated vehicle includes:

[0075] Selecting an aerodynamic reference point of an aerodynamic model of a simulated vehicle;

[0076] Calculate the frontal area parameters of the aerodynamic model of the simulated vehicle;

[0077] Calculate air density parameters of the aerodynamic model of the simulated vehicle;

[0078] An aerodynamic model of a simulated vehicle is obtained based on an aerodynamic reference point, a frontal area parameter and an air density parameter;

[0079] The actual aerodynamic parameters of the target vehicle include:

[0080] The relationship curves between the target vehicle’s drag coefficient, lateral force coefficient, lift coefficient and wind direction, and the relationship curves between the rolling moment coefficient, pitching moment coefficient, yaw moment coefficient and wind direction.

[0081] Specifically, the relationship curves of the drag coefficient, the lateral force coefficient, the lift coefficient and the wind direction, and the relationship curves of the roll moment coefficient, the pitch moment coefficient, the yaw moment coefficient and the wind direction adopt the relationship curves of the target vehicle.

[0082] Optionally, a projection point on the ground of a midpoint of a line connecting a front axle center and a rear axle center of the simulated vehicle is selected as an aerodynamic reference point.

[0083] Specifically, when selecting the aerodynamic reference point, according to SAE J1594 (American Society of Automotive Engineering "Vehicle Aerodynamics Terminology"), the aerodynamic reference point is usually defined as the middle position of the wheelbase and the reference length (generally refers to the wheelbase of the vehicle) on the ground, that is, the center position of the line connecting the center of the front axle and the center of the rear axle is projected on the ground. Therefore, for ordinary motor vehicles, its X coordinate is the negative value of half the wheelbase. In addition, the lateral (Y) coordinate is zero and the height (Z) is close to zero (if the origin of the spring mass coordinate system is defined at the ground plane under the design load conditions, it is zero).

[0084] Optionally, the frontal area parameter is calculated based on the actual appearance size parameter of the target vehicle and the ground clearance of the target vehicle.

[0085] Specifically, the frontal area is the projection area of ​​the vehicle in the direction of travel. If the project vehicle's dimensions and ground clearance are known, the frontal area can be calculated;

[0086] Optionally, the air density parameter is 1.202kg / m 3 .

[0087] Specifically, the working environment is set at a temperature of 293K and a standard atmospheric pressure of 1.01.3KPa. The molar mass of the gas is 22.4 liters, and the average molecular mass of air is 29. Using the ideal gas state equation PV=nRT, the air density is 1.202kg / m3, where P is pressure (Pa), V is gas volume (m 3 ), n is the amount of substance in the gas (mol), R is the ideal gas constant, R≈8.314J / (mol.K), T is the temperature (K), and M is the molar mass of the gas.

[0088] Optionally,

[0089] The power and transmission system model of the simulated vehicle includes:

[0090] Select the pure electric vehicle reference model in Carsim;

[0091] The real braking system parameters of the target vehicle are used to adjust the reference model of the pure electric vehicle to obtain the power and transmission system model of the simulated vehicle;

[0092] The actual braking system parameters of the target vehicle include:

[0093] A curve of the relationship between the speed and torque of the power motor of the target vehicle is obtained by fitting the peak speed and peak torque of the target vehicle;

[0094] Equivalent moment of inertia, damping and stiffness of the transmission of the final reducer and differential.

[0095] Specifically, if Figure 2 As shown in the figure, the relationship curve between the power motor speed and torque is fitted based on the peak speed and peak torque parameters. The transmission equivalent moment of inertia, damping, stiffness and other parameters of the internal "main reducer + differential" can be selected from the parameters of the target vehicle. Slight changes in the above parameters will basically not have a significant impact on the simulation results.

[0096] Optionally,

[0097] The braking system model of the simulated vehicle includes:

[0098] Select the hydraulic brake system model in Carsim;

[0099] The hydraulic brake system model is adjusted using the real brake system parameters of the target vehicle to obtain the brake system model of the simulated vehicle;

[0100] The target vehicle’s braking system parameters include:

[0101] The relationship between the target vehicle's front and rear axle brake input pressure and braking torque, the braking delay time, the longitudinal slip rate threshold for ABS device opening / closing, the minimum operating speed of the ABS device, and the ratio of the front and rear wheel transmission pressure to the pipeline pressure.

[0102] Specifically, the braking process of the braking system in Carsim is as follows Figure 3 As shown in the figure, the input pressure is adjusted by the load-sensing proportional valve to output the transmission pressure of each axle. The transmission pressure is adjusted by the ABS device to output the supply pressure. The high-pressure oil enters the brake wheel cylinder through the brake oil pipe to achieve vehicle braking. The braking system in Carsim is hydraulic braking. The relationship between the input pressure and braking torque of the front and rear axle brakes has been built based on the actual vehicle measured parameter list. Among them, the parameters such as the braking delay time, the longitudinal slip rate threshold for the ABS device to open / close, the minimum operating speed of the ABS device, and the ratio of the front and rear wheel transmission pressure to the pipeline pressure can be selected from vehicles close to the target vehicle. Combined with the real vehicle parameters, the braking system parameters are obtained to obtain the braking system model.

[0103] Optionally, the steering system parameters of the target vehicle include:

[0104] The relationship between the moment of inertia of the steering column, the moment of inertia of the steering system, the damping characteristics of the steering column, the hysteresis torque of the steering column, the reference hysteresis angle of the steering column, the lateral offset of the kingpin axis, the kingpin inclination angle, the X-coordinate of the center of the kingpin axis, the kingpin caster angle, the steering gear type, whether it has power assistance, the steering gear transmission ratio, the C characteristic of the steering system, the speed-sensitive ground friction steering torque, the power steering system, the power assistance torque, the power assistance speed, and the torsion bar torque.

[0105] Specifically, the steering system model in Carsim can be simplified by the following parts: (1) Basic parameters of the steering system, including the moment of inertia of the steering column, the moment of inertia of the steering system, the damping characteristics of the steering column, the steering column hysteresis torque (referring to half of the torque difference measured when turning the steering wheel left and right when only the steering column assembly is considered. The steering column hysteresis torque is an important indicator to measure the efficiency and smoothness of the steering column system. High hysteresis usually means that there is a large friction during the steering process), and the steering column reference hysteresis angle (Hysteresis ref. Angle), which refers to the angle range that the steering wheel needs to turn when the friction or hysteresis torque gradually decreases from the maximum value to the minimum value or increases from the minimum value to the maximum value during the process of steering from left to right or from right to left. Usually, the steering column reference hysteresis angle is defined as 1 / 3 of the angle required to complete 95% of the torque change. This means that if the total torque change from one extreme value to another requires the steering wheel to turn a certain angle, then the steering column reference hysteresis angle is 1 / 3 of this angle. These data use the actual parameters of the target vehicle.

[0106] (2) Kingpin geometry parameters, such as Figure 4 As shown, it includes the lateral offset of the kingpin axis, also known as the kingpin offset or kingpin offset, which refers to the distance from the intersection of the kingpin and the ground to the center of the tire contact. When the intersection of the kingpin axis is on the inside of the wheel centerline, the offset is positive; if it is on the outside, it is negative, the kingpin inclination angle (positive inward), the X-coordinate at the center of the kingpin axis, and the kingpin caster angle.

[0107] (3) Including parameters such as steering gear type (rack and pinion, recirculating ball), power steering, steering gear ratio, steering system C characteristic, Speed-Sensitive Ground-Friction Steer Torque (speed-sensitive ground-friction steering torque refers to the torque effect on the steering system caused by the friction between the ground and the tires due to changes in vehicle speed when the vehicle is turning), Power Steering System, and the relationship between the power torque and speed, torsion bar torque, etc.

[0108] Combined with the real vehicle parameters, the steering system model is obtained.

[0109] Optionally,

[0110] The tire model of the simulated vehicle includes:

[0111] Use the internal tire model in Carsim or the Pacejka5.2 tire model;

[0112] The internal tire model or the Pacejka5.2 tire model is adjusted using the real tire test data of the target vehicle to obtain the tire model of the simulated vehicle;

[0113] The tire test data of the target vehicle includes:

[0114] The effective rolling radius of the tire, the free radius of the tire, the vertical stiffness of the tire, the vertical maximum load, the wheel rolling resistance coefficient, the tire width, the tire moment of inertia, the longitudinal slack length of the tire, the lateral slack length of the tire and the speed threshold that has no effect on the lateral slack length of the tire.

[0115] Specifically, the tire model in Carsim can be simplified into the following parts.

[0116] (1) Tire vertical characteristic parameters, including the effective rolling radius of the tire, the free radius of the tire, the vertical stiffness of the tire and the maximum vertical load.

[0117] (2) Wheel rolling resistance coefficient and tire width.

[0118] (3) Tire model. Carsim tire models include internal tire models and Pacejka5.2 tire models. Other tire models can also be connected externally. Usually, the internal tire model is used for modeling. The internal tire model consists of the longitudinal force, lateral force, self-aligning moment and camber stiffness of the tire. The Pacejka5.2 tire model is called Magic Formula 5.2, which is also a mathematical model used to express tire forces. It is usually given by difference or function and method based on tire test data.

[0119] (4) Tire dynamic characteristic parameters, including tire moment of inertia, tire longitudinal slack length, tire lateral slack length, and vehicle speed threshold at which lateral slack length does not take effect.

[0120] Combined with the real vehicle parameters, the tire model is obtained.

[0121] Embodiment 2:

[0122] This embodiment is based on the dynamic model of the simulated vehicle established in the first embodiment, and is adjusted according to the empirical formula and referenced to the actual working conditions. In the vehicle driving stability test, the double lane change condition is mostly used as the test condition of the vehicle dynamic model. Therefore, the vehicle is selected at a speed of 20km / h to complete the simulation test of the double lane change condition. The test results are as follows: Figures 5a-5f As shown, the fluctuation range of the lateral displacement under the double lane-changing condition at a speed of 20 km / h is between 0m and 3.5m, the variation range of the lateral acceleration is -0.078g to 0.077g, the variation range of the roll angle is -0.14deg to 0.46deg, the yaw angular velocity varies between -7.7deg / s and 7.6deg / s, the variation range of the sideslip angle is -0.49deg to 0.51deg, and the maximum steering angle of the steering wheel is 4deg. The vehicle can maintain relatively stable driving under its maximum speed condition, and the dynamic model of the simulated vehicle can be used to complete the simulation test.

[0123] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A vehicle dynamics modeling method based on Carsim, characterized in that: include: Based on the real appearance size parameters of the target vehicle, a body parameter model of the simulated vehicle is established; Based on the real aerodynamic parameters of the target vehicle, an aerodynamic model of the simulated vehicle is established; Based on the real power and transmission system parameters of the target vehicle, establish the power and transmission system model of the simulated vehicle; Based on the real braking system parameters of the target vehicle, a braking system model of the simulated vehicle is established; Based on the real steering system parameters of the target vehicle, a steering system model of the simulated vehicle is established; Based on the real tire test data of the target vehicle, a tire model of the simulation vehicle is established; A dynamic model of the simulated vehicle is established based on the vehicle body parameter model, the aerodynamic model, the power and transmission system model, the braking system model, the steering system model and the tire model.

2. The vehicle dynamics modeling method based on Carsim according to claim 1, characterized in that: The actual appearance size parameters of the target vehicle include: The target vehicle's body length, body width, body height, vehicle mass, sprung mass, left front unsprung mass, right front unsprung mass, left rear unsprung mass, right rear unsprung mass, roll moment of inertia, pitch moment of inertia, yaw moment of inertia, longitudinal distance from the center of mass to the front axle, longitudinal distance from the center of mass to the rear axle, vertical height from the center of mass to the ground, front axle load, rear axle load, sprung mass, front axle unsprung mass, rear axle unsprung mass, and loaded mass.

3. The vehicle dynamics modeling method based on Carsim according to claim 1, characterized in that: The aerodynamic model of the simulated vehicle is established including: Selecting an aerodynamic reference point of an aerodynamic model of a simulated vehicle; Calculate the frontal area parameters of the aerodynamic model of the simulated vehicle; Calculate air density parameters of the aerodynamic model of the simulated vehicle; An aerodynamic model of a simulated vehicle is obtained based on an aerodynamic reference point, a frontal area parameter and an air density parameter; The actual aerodynamic parameters of the target vehicle include: The relationship curves between the target vehicle’s drag coefficient, lateral force coefficient, lift coefficient and wind direction, and the relationship curves between the rolling moment coefficient, pitching moment coefficient, yaw moment coefficient and wind direction.

4. The vehicle dynamics modeling method based on Carsim according to claim 3 is characterized in that: The projection point on the ground of the midpoint of the line connecting the center of the front axle and the center of the rear axle of the simulated vehicle is selected as the aerodynamic reference point.

5. The vehicle dynamics modeling method based on Carsim according to claim 3, characterized in that: The frontal area parameter is calculated based on the actual appearance size parameter of the target vehicle and the ground clearance of the target vehicle.

6. The vehicle dynamics modeling method based on Carsim according to claim 3, characterized in that: The air density parameter is 1.202 kg / m 3 .

7. The vehicle dynamics modeling method based on Carsim according to claim 1, characterized in that: The establishment of the power and transmission system model of the simulated vehicle includes: Select the pure electric vehicle reference model in Carsim; The real braking system parameters of the target vehicle are used to adjust the reference model of the pure electric vehicle to obtain the power and transmission system model of the simulated vehicle; The actual braking system parameters of the target vehicle include: A curve of the relationship between the speed and torque of the power motor of the target vehicle, wherein the curve is obtained by fitting the peak speed and peak torque of the target vehicle; Equivalent moment of inertia, damping and stiffness of the transmission of the main reducer and differential.

8. The vehicle dynamics modeling method based on Carsim according to claim 1, characterized in that: The brake system model of the simulated vehicle is established including: Select the hydraulic brake system model in Carsim; The hydraulic brake system model is adjusted using the real brake system parameters of the target vehicle to obtain the brake system model of the simulated vehicle; The braking system parameters of the target vehicle include: The relationship between the target vehicle's front and rear axle brake input pressure and braking torque, the braking delay time, the longitudinal slip rate threshold for ABS device opening / closing, the minimum operating speed of the ABS device, and the ratio of the front and rear wheel transmission pressure to the pipeline pressure.

9. The vehicle dynamics modeling method based on Carsim according to claim 1, characterized in that: The steering system parameters of the target vehicle include: The relationship between the moment of inertia of the steering column, the moment of inertia of the steering system, the damping characteristics of the steering column, the hysteresis torque of the steering column, the reference hysteresis angle of the steering column, the lateral offset of the kingpin axis, the kingpin inclination angle, the X-coordinate of the center of the kingpin axis, the kingpin caster angle, the steering gear type, whether it has power assistance, the steering gear transmission ratio, the C characteristic of the steering system, the speed-sensitive ground friction steering torque, the power steering system, the power assistance torque, the power assistance speed, and the torsion bar torque.

10. The vehicle dynamics modeling method based on Carsim according to claim 1, characterized in that: The tire model of the simulated vehicle is established including: Use the internal tire model in Carsim or the Pacejka5.2 tire model; The internal tire model or the Pacejka5.2 tire model is adjusted using the real tire test data of the target vehicle to obtain the tire model of the simulated vehicle; The tire test data of the target vehicle includes: The effective rolling radius of the tire, the free radius of the tire, the vertical stiffness of the tire, the vertical maximum load, the wheel rolling resistance coefficient, the tire width, the tire moment of inertia, the longitudinal slack length of the tire, the lateral slack length of the tire and the speed threshold that has no effect on the lateral slack length of the tire.

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