A vehicle dynamics model modeling and simulation method suitable for intelligent control

Abstract

The application provides a vehicle dynamics model modeling and simulation method suitable for intelligent control, comprising the following steps: establishing an Adams multi-body dynamics model; running the Adams multi-body dynamics model to obtain simulation results; performing data conversion and Carsim file generation; importing a.par file and perfecting a Carsim whole vehicle model; and performing intelligent control related whole vehicle dynamics simulation. The vehicle dynamics model modeling and simulation method suitable for intelligent control is suitable for establishing and simulating a vehicle intelligent control system simulation model in an early stage of vehicle development, can directly utilize chassis structure design parameters to model a whole vehicle characteristic model, the established model environment is convenient for developing a control system, shortens a development cycle and reduces cost; and the established dynamics model can also be applied to a whole vehicle hardware-in-the-loop simulation system such as a driving simulator, and improves model precision.

Description

Technical Field

[0001] This invention belongs to the field of automotive performance development and testing, and in particular relates to a method for modeling and simulating vehicle dynamics models suitable for intelligent control. Background Technology

[0002] Currently, vehicle dynamics models are mainly divided into two categories. The first category is multibody dynamics models based on physical structures, such as Adams / Car and MotionView. The second category is vehicle dynamics models based on system characteristics, such as CarSim and CarMaker. The first type of model establishes system dynamic equations by creating key components and topology, performing static, kinematic, and dynamic analyses on the system and the entire vehicle. It is suitable for detailed design of hard points and component parameters in chassis development. However, due to the need to solve a large number of constraint equations, the computation time is long, and real-time simulation is generally not possible. The second type of model utilizes the characteristics of each system to build the model, mainly used to predict and simulate the vehicle's handling stability, braking performance, dynamics, and economy. Because the model's degrees of freedom are greatly reduced, the running speed is 3-6 times faster than real-time. Co-simulation with software such as Simulink is widely used in the development of modern automotive control systems.

[0003] Modern automobiles extensively utilize control systems, such as Electronic Power Steering (EPS), Anti-lock Braking System (ABS), Electronic Stability Control (ESC), Rear-wheel Steering (RWS), Lane Keeping Assist (LKA), Adaptive Cruise Control (ACC), Active Suspension (AS), and Semi-active Suspension (SAS). The development of these control systems requires real-time vehicle dynamics models, i.e., second-type models. However, in the early stages of vehicle development, information from these second-type models cannot be obtained through experimentation and must be calculated using first-type models. Therefore, generating second-type models from first-type models has become a crucial step in the development of modern automotive control systems. Summary of the Invention

[0004] In view of this, the present invention aims to propose a vehicle dynamics modeling and simulation method suitable for intelligent control, so as to solve the modeling problem of establishing a vehicle model based on system characteristics from structural parameters in the early stage of vehicle development and the real-time problem of intelligent control co-simulation.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] A method for modeling and simulating vehicle dynamics suitable for intelligent control includes the following steps:

[0007] S1. Establish the Adams multibody dynamics model;

[0008] S2. Run the Adams multibody dynamics model to obtain simulation results;

[0009] S3. Perform data conversion and generate Carsim files;

[0010] Importing S4 and .par files and perfecting the Carsim vehicle model;

[0011] S5, intelligent control-related vehicle dynamics simulation.

[0012] Furthermore, the establishment of the Adams multibody dynamics model in step S1 includes the following steps:

[0013] A1. Use Adams / Car software to create an Adams / Car.tpl template file based on the topology of each component;

[0014] A2. Generate a subsystem using a template file, update the subsystem model parameters based on the hard point location, bushing stiffness, and spring stiffness information of the developed vehicle model, and save it as a subsystem.sub file;

[0015] A3. Use the subsystem model to build a suspension assembly model, update relevant parameters such as wheelbase, tire diameter, and stiffness, and save it as an assembly model.asy file.

[0016] Furthermore, the step S2 of obtaining simulation results by running the Adams multibody dynamics model includes the following steps:

[0017] B1. Create a batch program file named My.bat;

[0018] B2. Call the Adams startup program mdi.bat;

[0019] B3. Execute the .cmd command file, and perform analysis, calculation and parameter output for various working conditions, and save the output parameters to the .txt file.

[0020] Furthermore, the data conversion and Carsim file generation described in step S3 includes the following steps:

[0021] C1. Compile the Matlab data processing program file suspensionKC.m;

[0022] C2. Call the .txt file generated in step B3, perform numerical and unit conversions based on the differences in direction definitions between the Adams output parameters and the Carsim modeling parameters, and store the converted results in the .mat file;

[0023] C3. Compile the Matlab data processing program makepar.m file, which uses the data transformed in step C2 and the Carsim independent template to be created to generate the .par file.

[0024] Furthermore, the import of the .par file and the improvement of the Carsim vehicle model in step S4 include the following steps:

[0025] D1. Import the .par file from step C3 into Carsim software and complete the parameter information;

[0026] D2. Set the vehicle parameter information and complete the modeling of the Carsim vehicle model.

[0027] Furthermore, the intelligent control-related vehicle dynamics simulation in step S5 includes the following steps:

[0028] E1. Configure the Carsim vehicle simulation conditions;

[0029] E2. Set the Carsim solver to Simulink co-simulation mode by setting the input and output parameters in Carsim.

[0030] E3. Data exchange with the main simulation environment Simulink; in the co-simulation, the Carsim vehicle model appears in the form of an S-function.

[0031] E4. The control strategy is implemented in Simulink. After the simulation is completed, the data results and simulation animation can be viewed in the CARSIM software.

[0032] Compared with existing technologies, the vehicle dynamics modeling and simulation method for intelligent control described in this invention has the following advantages:

[0033] (1) The present invention provides a vehicle dynamics modeling and simulation method suitable for intelligent control. This method is suitable for the establishment and simulation of vehicle intelligent control system simulation model in the early stage of vehicle development. It can directly use chassis structure design parameters to model the whole vehicle characteristic model. The model environment is convenient for the development of control system, shortens the development cycle and reduces costs. The dynamic model can also be applied to whole vehicle hardware-in-the-loop simulation system such as driving simulator to improve model accuracy. Attached Figure Description

[0034] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0035] Figure 1This is a schematic diagram of the overall method flow according to an embodiment of the present invention. Detailed Implementation

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0037] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0038] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] like Figure 1 As shown, a method for modeling and simulating vehicle dynamics suitable for intelligent control includes the following steps:

[0041] S1. Establish the Adams multibody dynamics model;

[0042] S2. Run the Adams multibody dynamics model to obtain simulation results;

[0043] S3. Perform data conversion and generate Carsim files;

[0044] Importing S4 and .par files and perfecting the Carsim vehicle model;

[0045] S5, intelligent control-related vehicle dynamics simulation.

[0046] This method is suitable for establishing and simulating vehicle intelligent control system simulation models in the early stages of vehicle development. Steps two, three, and four utilize chassis structure design parameters to model the overall vehicle characteristics. The model environment established in step five facilitates the development of the control system, shortens the development cycle, and reduces costs. The dynamic model established in step five can also be applied to vehicle hardware-in-the-loop simulation systems such as driving simulators to improve model accuracy.

[0047] The establishment of the Adams multibody dynamics model in step S1 includes the following steps:

[0048] A1. Use Adams / Car software to create an Adams / Car.tpl template file based on the topology of each component;

[0049] A2. Generate a subsystem using a template file, update the subsystem model parameters based on the hard point location, bushing stiffness, and spring stiffness information of the developed vehicle model, and save it as a subsystem.sub file;

[0050] A3. Use the subsystem model to build a suspension assembly model, update relevant parameters such as wheelbase, tire diameter, and stiffness, and save it as an assembly model.asy file.

[0051] In this embodiment, step one involves establishing an Adams multibody dynamics model. Adams / Car software is used to create files such as the suspension system .tpl template, steering system .tpl template, and stabilizer bar system .tpl template based on the topology of each component.

[0052] The suspension subsystem, steering subsystem, and stabilizer bar system are generated using template files. The subsystem model parameters are updated based on specific information such as the hardpoint location, bushing stiffness, and spring stiffness of the developed vehicle model. The models are then saved as suspension subsystem.sub, steering subsystem.sub, and stabilizer bar system.sub files, respectively.

[0053] A suspension assembly model is created using subsystem models such as suspension, steering, and stabilizer bar. Relevant parameters such as wheelbase, tire diameter, and stiffness are updated and saved as an assembly model.asy file.

[0054] The steps in step S2 to obtain simulation results by running the Adams multibody dynamics model include the following steps:

[0055] B1. Create a batch program file named My.bat;

[0056] B2. Call the Adams startup program mdi.bat;

[0057] B3. Execute the .cmd command file, and perform analysis, calculation and parameter output for various working conditions, and save the output parameters to the .txt file.

[0058] In this embodiment, step two involves running the Adams model to obtain simulation results. A batch program My.bat is created. This program first calls the Adams startup program mdi.bat and then executes the .cmd command file. The command file includes analyses, calculations, and parameter outputs for various operating conditions. The content of the command file varies slightly depending on the suspension type. Taking a certain front independent suspension as an example, the analysis conditions mainly include parallel wheel bounce, roll, steering, parallel longitudinal force loading, reverse lateral force loading, reverse self-centering torque loading, and same-direction self-centering torque loading. The output parameters for each operating condition are set according to specific requirements, and the output parameters are saved to a .txt file.

[0059] The data conversion and Carsim file generation described in step S3 include the following steps:

[0060] C1. Compile the Matlab data processing program file suspensionKC.m;

[0061] C2. Call the .txt file generated in step B3, perform numerical and unit conversions based on the differences in direction definitions between the Adams output parameters and the Carsim modeling parameters, and store the converted results in the .mat file;

[0062] C3. Compile the Matlab data processing program makepar.m file, which uses the data transformed in step C2 and the Carsim independent template to be created to generate the .par file.

[0063] In this embodiment, step three involves data conversion and Carsim file (.par format) generation. A Matlab data processing program, `suspensionKC.m`, is created to call the `.txt` result file generated in the previous step. Based on the differences in direction definitions between the Adams output parameters and the Carsim modeling parameters, numerical and unit conversions are performed, and the converted results are stored in a `.mat` file. A Matlab data processing program, `makepar.m`, is then created to generate the corresponding suspension K-characteristics (.par), C-characteristics (.par), and steering system (.par) files using the converted data and the required Carsim independent suspension template. Some parameters, such as unsprung mass and shock absorber damping characteristics, do not need to be set.

[0064] The import of the .par file and the completion of the Carsim vehicle model in step S4 include the following steps:

[0065] D1. Import the .par file from step C3 into Carsim software and complete the parameter information;

[0066] D2. Set the vehicle parameter information and complete the modeling of the Carsim vehicle model.

[0067] In this embodiment, step four involves importing .par files and completing the vehicle model. The suspension system K-characteristics.par file, C-characteristics.par file, and steering system.par file are imported into Carsim software, and information such as unsprung mass, shock absorber damping characteristics, and lever ratio are completed. Steering system flexibility and related four-wheel alignment parameters can be directly modified in the steering template. Simultaneously, information such as the vehicle's sprung mass, moment of inertia, and tire characteristics are set to complete the vehicle modeling.

[0068] The intelligent control-related vehicle dynamics simulation in step S5 includes the following steps:

[0069] E1. Configure the Carsim vehicle simulation conditions;

[0070] E2. Set the Carsim solver to Simulink co-simulation mode by setting the input and output parameters in Carsim.

[0071] E3. Data exchange with the main simulation environment Simulink; in the co-simulation, the Carsim vehicle model appears in the form of an S-function.

[0072] E4. The control strategy is implemented in Simulink. After the simulation is completed, the data results and simulation animation can be viewed in the CARSIM software.

[0073] In this embodiment, step five involves intelligent control-related vehicle dynamics simulation. To meet the complex control strategy requirements, the Carsim solver is set to Simulink co-simulation mode during the intelligent control-related vehicle dynamics simulation. In the co-simulation, the Carsim vehicle model appears as an S-function. Data exchange with the main simulation environment Simulink is achieved by setting input and output parameters in Carsim. The control strategy is implemented in Simulink. After the simulation is completed, the data results and simulation animation can be viewed in the Carsim software. The co-model can also be applied to a hardware-in-the-loop simulation system.

[0074] Example 1

[0075] First, a multibody dynamics model of the vehicle model is created in Adams / car.

[0076] Create an independent suspension .tpl template file according to the front suspension type of the vehicle model. The main function of the template file is to define the topology of the model, that is, which components are included in the model and the topological relationships between the components. For example, the front double wishbone independent suspension includes the main components such as the front subframe, steering knuckle, upper delta arm, lower sway bar, lower oblique arm, shock absorber, and spring. Each component is connected by constraint pairs such as rubber bushings and ball joints. At the same time, it is necessary to establish a communicator for the front suspension to exchange information with other systems. The template files for the steering system and rear suspension are similar to those for the front suspension.

[0077] The .tpl template file is used to generate the .sub subsystem file. The subsystem file includes the components and topology relationships in the template file. It can update specific hard point locations, bushing stiffness, spring stiffness and other characteristic parameters according to different vehicle models. The updated parameters will be retained in the .sub file without modifying the .tpl template file. This makes it easy to implement multiple specific subsystem files (representing specific vehicle model information) corresponding to the same template file (representing topology relationships).

[0078] A front suspension assembly model (.asy) is created using the front suspension subsystem and steering subsystem. In addition to the components and topological relationships of the steering and front suspension subsystems, the assembly model adjusts specific constraints based on the communicator's matching status. For example, it determines whether the steering gear is mounted on the subframe or the vehicle body (in this case, the ground) based on the communicator settings. The feature parameters in the assembly model use subsystem file parameters; some parameters, such as tire diameter, tire stiffness, and wheelbase, need to be set within the assembly model.

[0079] Suspension dynamics simulation was then performed in Adams / car.

[0080] The front suspension simulation mainly includes K-characteristic simulation for two working conditions: same-direction wheel bounce and roll; steering simulation; and C-characteristic simulation for four working conditions: same-direction longitudinal force, opposite-direction lateral force, opposite-direction self-centering torque, and same-direction self-centering torque. The simulation of wheel hop in the same direction mainly outputs the variation of parameters such as toe angle, camber angle, wheel center longitudinal displacement, lateral displacement, wheel rotation angle, and suspension stiffness with wheel hop. The simulation of roll condition mainly outputs the variation of total roll stiffness with suspension roll angle. The simulation of steering mainly outputs the steering ratio, kingpin alignment parameters, and the nonlinear relationship between left and right wheel steering. The simulation of longitudinal force in the same direction mainly outputs the variation of toe angle, camber angle, and wheel center longitudinal displacement with longitudinal force. The simulation of lateral force in the opposite direction mainly outputs the variation of toe angle, camber angle, and wheel center lateral displacement with longitudinal force. The simulation of self-centering torque in the opposite direction mainly outputs the variation of toe angle and camber angle with self-centering torque. The simulation of self-centering torque in the same direction mainly outputs the variation of toe angle with self-centering torque. The parameter characteristics of this condition, together with the characteristics of the self-centering torque condition, will be used to calculate the steering system compliance characteristics. The above output parameters are output to .txt files according to the conditions, forming 7 .txt files.

[0081] The next step is to use the Matlab program suspensionKC.m to perform data calculations and related transformations.

[0082] Since the definitions of direction, units, and initial values ​​of Adams output parameters differ from those of Carsim modeling parameters, data conversion is required first. For example, in Adams output parameters, wheel angles are defined as toe angles, with the positive direction being toe in. In Carsim, some wheel angles are defined as steer angles, with the positive direction being counter-clockwise in the top view. The sign of the left front wheel value needs to be changed during conversion. Similarly, in Adams output parameters, wheel camber angles are defined as camber angles, with the positive direction being top out. In Carsim, some wheel camber angles are defined as inclination angles, with the positive direction being clockwise in the rear view. The sign of the left front wheel value needs to be changed during conversion. In Adams output parameters, the positive direction of the wheel center longitudinal displacement is backward, while in Carsim, the positive direction is forward. The sign of the value needs to be changed during conversion. In Adams output parameters, the unit of the self-aligning torque (aligning_torque) is Nmm, while in Carsim, the unit is Nm. The value needs to be multiplied by 0.001 during conversion. In the Carsim model, the horizontal axis of the steering system compliance is the sum of the self-aligning torques of the left and right wheels, with the positive direction being counter-clockwise in the top view, and the vertical axis being steer. The angle can be obtained by subtracting the steering angle under reverse return torque from the steering angle under same return torque. In the Carsim model, the steering gear ratio, kingpin inclination angle, kingpin caster angle, and kingpin offset at the wheel center can be the average value within a range of ±45 degrees for the steering wheel angle. The steering geometry is described by the Pitman arm angle (steering wheel angle / gear ratio) and the left and right wheel steer angles within the steering limit range.

[0083] The next step is to use the Matlab data processing program makepar.m file to create the Carsim simulation file.

[0084] Adams' result files can be used to convert steering system characteristics, suspension system K characteristics, and suspension system C characteristics into data, and can generate corresponding steering system.par, suspension K characteristic.par, and suspension C characteristic.par files. Some parameters, such as shock absorber damping characteristics, unsprung mass, and initial toe-in / camber angle, can be left uninputted for now. These parameters are generally Adams modeling input data or design values ​​and can be set directly in the subsequent Carsim software.

[0085] Create a Carsim vehicle model.

[0086] Open Carsim software, create a complete vehicle model, import the steering system.par and front and rear suspension.par files and update them into the complete vehicle model. Improve the information such as unsprung mass and damping characteristics of the suspension system, the power assist characteristics and stiffness characteristics of the steering system, set the sprung mass, moment of inertia, and wheelbase of the body system, and improve the tire characteristics of the tire system to complete the modeling of the complete vehicle.

[0087] A Carsim-Simulink co-simulation model for rear-wheel steering was established.

[0088] Set the Carsim solver to Models: Simulink co-simulation mode. In the configuration file, set the input parameters Import Channels to include rear wheel steering angles IMP_STEER_L2 and IMP_STEER_R2, Mode to Add, and InitialValus to 0, meaning the rear steering angle is directly input from the outside. Set the output parameters Export Channels to include vehicle speed Vx, steering wheel angle Steer-SW, yaw rate AVz, and center of gravity sideslip angle Beta. Select the corresponding Simulink Model: MdlRws.slx. In this file, the Carsim vehicle model participates in the closed-loop simulation in the form of an S-function. The rear wheel steering angle is determined by the steering wheel angle, vehicle speed, and yaw rate. The control strategy is specifically implemented in the Simple RWS Controller. When simulating rear wheel steering, it is also necessary to add Miscellaneous: VS Commands and add the "opt_steer_ext(2)4" command.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for modeling and simulation of vehicle dynamics model suitable for intelligent control, characterized in that: The method comprises the following steps: S1, establishing an Adams multi-body dynamics model; S2, running the Adams multi-body dynamics model to obtain simulation results; S3, data conversion and Carsim file generation; S4,.par file import and Carsim whole vehicle model improvement; S5, intelligent control related whole vehicle dynamics simulation; The running of the Adams multi-body dynamics model in step S2 to obtain simulation results comprises the following steps: B1, compiling a batch program My.bat file; B2, calling an Adams start program mdi.bat; B3, executing a.cmd command file, and performing analysis, calculation and parameter output on the command file under multiple working conditions, and saving the output parameters to a.txt file; The data conversion and Carsim file generation in step S3 comprise the following steps: C1, compiling a Matlab data processing program suspensionKC.m file; C2, calling the.txt file generated in step B3, performing numerical conversion and unit conversion according to the direction definition difference between the Adams output parameters and the Carsim modeling parameters, and storing the converted results in a.mat file; C3, compiling a Matlab data processing program makepar.m file, and generating a.par file by using the data converted in step C2 and the Carsim independent template to be established.

2. The method for modeling and simulation of vehicle dynamics model suitable for intelligent control according to claim 1, characterized in that: The establishment of the Adams multi-body dynamics model in step S1 comprises the following steps: A1, applying Adams / Car software to establish an Adams / Car.tpl template file according to the topological structure of each component; A2, generating a subsystem by using the template file, updating the subsystem model parameters according to the hard point position, bushing stiffness and spring stiffness information of the developed vehicle model, and saving as a subsystem.sub file; A3, establishing a suspension assembly model by using the subsystem model, updating related parameters such as wheelbase, tire diameter and stiffness, and saving as an assembly model.asy file.

3. The method for modeling and simulation of vehicle dynamics model suitable for intelligent control according to claim 1, characterized in that: The.par file import and Carsim whole vehicle model improvement in step S4 comprise the following steps: D1, importing the.par file in step C3 into the Carsim software, and improving the parameter information; D2, setting the whole vehicle parameter information, and completing the modeling of the Carsim whole vehicle model.

4. The method for modeling and simulation of vehicle dynamics model suitable for intelligent control according to claim 3, characterized in that: The intelligent control related whole vehicle dynamics simulation in step S5 comprises the following steps: E1, setting the Carsim whole vehicle simulation working condition; E2, setting the Carsim solver to a Simulink joint simulation form, and setting the input and output parameters in Carsim; E3, exchanging data with the main simulation environment Simulink, and the Carsim vehicle model appears in the form of an S function in the joint simulation; E4, the control strategy is realized in the form of Simulink, and the data results and simulation animation after simulation are viewed in the Carsim software.

Images