Simulink-based vehicle system simulation model and operation method thereof

Abstract

The invention discloses a Simulink-based vehicle system simulation model and an operation method thereof, and belongs to the technical field of automobile research and development simulation. Comprising a driver input model, an automatic gear shifting model, an engine model and a transmission system model. Selecting a simulation frequency; the input vehicle speed is transmitted to the whole vehicle resistance model, the automatic gear shifting model and the transmission system model; the current whole vehicle resistance is calculated; determining a current gear; calculating the engine rotating speed, the wheel end driving force, the vehicle acceleration and the current vehicle speed; and repeating the process until the preset time is finished. And comparing results. According to the method, the highly accurate simulation model is constructed, so that the period of the vehicle from design to verification is shortened, and the simulation accuracy and the verification efficiency are improved. A part of time-consuming physical test processes are replaced, and accurate prediction of the vehicle performance is realized. A simulation result is highly consistent with a test result, the difference is controlled within 2%, and a solid theoretical basis is provided for vehicle design.

Description

Technical Field

[0001] The invention relates to a vehicle system simulation model based on Simulink and an operation method thereof, belonging to the technical field of automobile research and development simulation. Background Art

[0002] In the traditional automotive R&D process, test verification and design improvement take up a lot of time, including the manufacture of physical prototype vehicles, multiple iterative tests, and subsequent design adjustments based on the test results. This series of processes is not only time-consuming and labor-intensive, but also increases R&D costs.

[0003] Automobile design involves the cross-integration of multiple disciplines, such as body structure, power system, chassis tuning, electronic control, etc. Each item needs to be verified through detailed calculation analysis, simulation and actual road tests to verify its effectiveness and reliability. In particular, with the rapid development of cutting-edge technologies such as new energy vehicles and autonomous driving, higher requirements are placed on the prediction accuracy and verification efficiency of vehicle performance. Traditional testing methods can no longer meet the needs of rapid iteration of research and development.

[0004] Therefore, there is an urgent need for an efficient and accurate simulation model to replace or optimize part of the physical test process and shorten the cycle from design to verification, thereby reducing R&D costs, accelerating product launch time, and enhancing the market competitiveness of enterprises. Summary of the invention

[0005] In order to solve the problems existing in the background technology, the present invention provides a vehicle system simulation model based on Simulink and an operation method thereof.

[0006] To achieve the above object, the present invention adopts the following technical scheme: a vehicle system simulation model based on Simulink, including a driver input model, providing the throttle opening and brake force required for the simulation working process;

[0007] The automatic gear shift model determines the gear position of the transmission based on the throttle opening and vehicle speed, and sends the vehicle gear position signal to the transmission system model;

[0008] The engine model is input into the engine model a universal characteristic curve and a friction torque characteristic curve of the engine of the simulated vehicle, and the torque of the engine of the simulated vehicle is obtained by looking up a table according to the throttle opening input in the driver input model and the engine speed inversely calculated in the transmission system model;

[0009] Transmission system model, including torque converter transmission model and gear transmission model, used to calculate wheel end driving force;

[0010] The vehicle resistance model is used to simulate the vehicle resistance.

[0011] The present invention provides a method for operating a vehicle system simulation model based on Simulink, the method comprising the following steps:

[0012] S1: setting model parameters according to the simulated vehicle and the simulated working conditions;

[0013] S101: Setting parameters of the driver input model;

[0014] S102: Setting parameters of an automatic shifting model;

[0015] S103: Setting parameters of the engine model;

[0016] S104: Setting parameters of the transmission system model;

[0017] S10401: Set the torque converter transmission model parameters and input the relationship between the hydraulic speed ratio and the torque ratio;

[0018] S10402: Set the gear transmission model parameters, including the main reduction ratio, wheel radius, and speed ratio of each gear.

[0019] S105: Setting parameters of the vehicle resistance model.

[0020] S2: Run the simulation model;

[0021] S201: Select simulation frequency;

[0022] S202: starting the simulation model, at which time the vehicle input speed is 0 km / h, and transmitting the input speed to the vehicle resistance model, the automatic shifting model, and the transmission system model respectively;

[0023] S203: The vehicle resistance model calculates the current vehicle resistance by inputting the vehicle speed;

[0024] The calculation formula of the vehicle resistance F is as follows:

[0025] F=Av 2 +Bv+C

[0026] Where:

[0027] v is the vehicle speed;

[0028] A, B, and C are all constants and are determined by table lookup.

[0029] S204: the automatic shift model determines the current gear position according to the input vehicle speed and the throttle opening in the driver input model, and transmits the gear position signal to the transmission system model;

[0030] S205: The transmission system model calculates the engine speed and the wheel-end driving force according to the gear position signal and the input vehicle speed;

[0031] S20501: Determine input speed and torque of the gear transmission model;

[0032] When the automatic shift model outputs the gear position of 1st or 2nd gear, the torque converter transmission model calls the preset speed ratio and torque ratio curve to calculate the speed and torque of the torque converter turbine. Since the torque converter turbine is rigidly connected to the input shaft of the gear system, the speed and torque of the turbine are the input speed and torque of the gear transmission model.

[0033] When the output gear of the automatic shift model is 3rd gear or higher, since the turbine and pump wheel of the torque converter are rigidly connected, the engine speed and torque are the input speed and torque of the gear transmission model;

[0034] S20502: The gear transmission model selects a gear ratio according to the corresponding gear;

[0035] S20503: Calculate the output speed and gear ratio of the torque converter transmission model;

[0036] Gear transmission ratio = gear ratio × final reduction ratio

[0037] Output speed of torque converter transmission model = gear ratio × input vehicle speed / (wheel radius × 2π)

[0038] S20504: The torque converter transmission model calculates the torque converter speed ratio;

[0039] Torque converter speed ratio = output speed of torque converter transmission model / engine speed at input vehicle speed

[0040] S20505: The torque converter transmission model determines the torque ratio by looking up a map;

[0041] S20506: The engine model calculates the torque converter output torque based on the engine speed and throttle opening:

[0042] Torque converter output torque = (engine combustion torque - engine friction torque) × torque ratio

[0043] S20507: The gear transmission model calculates the wheel end driving force based on the preset main reduction ratio, wheel radius, and gear transmission friction torque loss at different speeds:

[0044] Wheel end driving force =

[0045] (torque converter output torque - torque converter friction torque) × gear ratio × final reduction ratio / wheel radius;

[0046] S20508: Calculate the engine speed at the current speed:

[0047] Engine speed at current speed2 = Torque converter output torque / (torque converter capacity factor × torque converter diameter 5 ).

[0048] S206: Calculate vehicle acceleration;

[0049] Vehicle acceleration = (wheel end driving force - vehicle resistance) / vehicle mass.

[0050] S207: Calculate the current speed of the vehicle;

[0051] The current speed of the vehicle = input speed + vehicle acceleration × simulation frequency.

[0052] S208: Substitute the current vehicle speed of S207 into the input vehicle speed of S202 and repeat S202-S206 until the preset time is up, thus completing the vehicle simulation.

[0053] S3: Compare the simulation results with the experimental results.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] The present invention shortens the cycle from vehicle design to verification, reduces R&D costs, and improves simulation accuracy and verification efficiency by constructing a highly accurate simulation model. It not only replaces part of the time-consuming physical test process, but also achieves accurate prediction of vehicle performance through sophisticated computational analysis and simulation. The simulation results are highly consistent with the test results, with the difference controlled within 2%, providing a solid theoretical basis for vehicle design. In addition, the method also enhances the market competitiveness of enterprises, enabling them to launch new products faster and seize market opportunities. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 is a schematic diagram of a throttle-time curve of a driver input model of the present invention;

[0057] Figure 2 is a schematic diagram of a transmission shift line of an automatic shift model of the present invention;

[0058] Figure 3 It is a schematic diagram of the hydraulic speed ratio-torque ratio curve of the transmission system model;

[0059] Figure 4 It is a schematic diagram comparing theoretical and actual vehicle speeds;

[0060] Figure 5 This is a schematic diagram comparing theoretical and actual engine speed. DETAILED DESCRIPTION

[0061] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0062] A vehicle system simulation model based on Simulink, including

[0063] The driver input model, as the input of the entire simulation model, provides the throttle opening and brake force required for the simulation process and simulates the driver's operating behavior;

[0064] The automatic shift model includes the shift logic of the vehicle transmission. The gear position of the transmission is determined by the throttle opening and vehicle speed. When the simulated vehicle speed and the driver's throttle opening cross the shift line, the transmission performs an upshift or downshift operation and sends a vehicle gear position signal to the transmission system model.

[0065] Engine model, input the universal characteristic curve of the engine of the simulated vehicle (i.e. the combustion torque value of the engine at different throttle openings and different engine speeds) and the friction torque characteristic curve (i.e. the friction torque value of the engine at different engine speeds) into the engine model. If the friction torque characteristic curve of the engine of the simulated vehicle is unknown, it can be estimated using 25Nm. According to the throttle opening entered in the driver input model and the engine speed calculated back in the transmission system model, the torque of the engine of the simulated vehicle is obtained by looking up the table. Because the engine is rigidly connected to the transmission torque converter pump wheel, the engine torque is the pump wheel torque.

[0066] Transmission system model, including torque converter transmission model and gear transmission model, used to calculate wheel end driving force;

[0067] The vehicle resistance model is used to simulate the vehicle resistance.

[0068] The present invention provides a method for operating a vehicle system simulation model based on Simulink, the method comprising the following steps:

[0069] S1: setting model parameters according to the simulated vehicle and the simulated working conditions;

[0070] S101: Setting parameters of the driver input model;

[0071] S102: Setting parameters of an automatic shifting model;

[0072] S103: Setting parameters of the engine model;

[0073] S104: Setting parameters of the transmission system model;

[0074] S10401: Set the torque converter transmission model parameters and input the relationship between the hydraulic speed ratio and the torque ratio;

[0075] S10402: Set the gear transmission model parameters, including the main reduction ratio, wheel radius, and speed ratio of each gear.

[0076] S105: Setting parameters of the vehicle resistance model.

[0077] S2: Run the simulation model;

[0078] S201: Select simulation frequency;

[0079] S202: starting the simulation model, at which time the vehicle input speed is 0 km / h, and transmitting the input speed to the vehicle resistance model, the automatic shifting model, and the transmission system model respectively;

[0080] S203: The vehicle resistance model calculates the current vehicle resistance by inputting the vehicle speed;

[0081] The calculation formula of the vehicle resistance F is as follows:

[0082] F=Av 2 +Bv+C

[0083] Where:

[0084] v is the vehicle speed;

[0085] A, B, and C are all constants, which are related to factors such as vehicle weight and drag coefficient. They are determined by table lookup based on national standards and vehicle model.

[0086] S204: the automatic shift model determines the current gear position according to the input vehicle speed and the throttle opening in the driver input model, and transmits the gear position signal to the transmission system model;

[0087] S205: The transmission system model calculates the engine speed and the wheel-end driving force according to the gear position signal and the input vehicle speed;

[0088] S20501: Determine input speed and torque of the gear transmission model;

[0089] When the output gear of the automatic shift model is 1st gear or 2nd gear, the torque converter transmission model selects non-direct connection working condition for transmission. The torque converter transmission model calls the preset speed ratio and torque ratio curve to calculate the speed and torque of the torque converter turbine. Since the torque converter turbine is rigidly connected to the input shaft of the gear system, the speed and torque of the turbine are the input speed and torque of the gear transmission model.

[0090] When the output gear of the automatic shift model is 3rd gear or higher, the torque converter selects the direct-connection working condition. Since the turbine and pump wheel of the torque converter are rigidly connected, the engine speed and torque are the input speed and torque of the gear transmission model.

[0091] S20502: The gear transmission model selects a gear ratio (a transmission ratio of different gears of the gearbox) according to the corresponding gear.

[0092] S20503: Calculate the output speed and gear ratio of the torque converter transmission model;

[0093] Gear transmission ratio = gear ratio × final reduction ratio

[0094] Output speed of torque converter transmission model = gear ratio × input vehicle speed / (wheel radius × 2π)

[0095] S20504: The torque converter transmission model calculates the torque converter speed ratio;

[0096] Torque converter speed ratio = output speed of torque converter transmission model / engine speed at input vehicle speed

[0097] S20505: Torque converter transmission model is found by torque converter ratio Figure 3 The parameters determine the torque ratio;

[0098] S20506: The engine model calculates the torque converter output torque based on the engine speed and throttle opening:

[0099] Torque converter output torque =

[0100] (Engine combustion torque (obtained by looking up the universal characteristic curve) - engine friction torque) × torque ratio

[0101] S20507: The gear transmission model calculates the wheel-end driving force based on the preset main reduction ratio, wheel radius, and gear transmission friction torque loss at different speeds. If the gear transmission friction torque loss at different speeds of the transmission is unknown, 12Nm can be used for estimation:

[0102] Wheel end driving force =

[0103] (torque converter output torque - torque converter friction torque) × gear ratio × final reduction ratio / wheel radius;

[0104] S20508: Calculate the engine speed at the current speed:

[0105] Engine speed at current speed 2 = Torque converter output torque / (torque converter capacity factor × torque converter diameter 5 ).

[0106] S206: Calculate vehicle acceleration;

[0107] Vehicle acceleration = (wheel end driving force - vehicle resistance) / vehicle mass.

[0108] S207: Calculate the current speed of the vehicle;

[0109] The current speed of the vehicle = input speed + vehicle acceleration × simulation frequency.

[0110] S208: Substitute the current vehicle speed of S207 into the input vehicle speed of S202 and repeat S202-S206 until the preset time is up, thus completing the vehicle simulation.

[0111] S3: Compare the simulation results with the experimental results.

[0112] The difference between the simulation results of this model and the experimental values ​​is within 2%, which is within the acceptable range. The main reason affecting this error is that this simulation model does not simulate the motion state of the shifting process and the estimation error.

[0113] Embodiment 1:

[0114] S1:

[0115] The throttle in the driver model is 100%, the brake force is 0, and the vehicle starts moving from rest (vehicle speed is 0 km / h).

[0116] The final reduction ratio is 3.683 and the wheel radius is 0.31.

[0117] The vehicle resistance model is set to A=0.0361, B=0.926, C=153.54,

[0118] S2:

[0119] Select simulation frequency 01.1s;

[0120] The vehicle resistance model calculates the current vehicle resistance F=153.54N by inputting the vehicle speed. ;

[0121] The automatic shift model uses the vehicle speed of 0 km / h and the throttle opening of 100% to look up the table and concludes that the gear position is 1st gear.

[0122] The gear transmission model is based on the gear being 1st gear, and the gear ratio is 4.044 according to the table.

[0123] Gear ratio = 4.044 × 3.683 = 14.894

[0124] Output speed of torque converter transmission model = = 14.894 × 0 / (0.31 x 2π) = 0

[0125] Torque converter ratio = 0 / 750 = 0

[0126] The torque converter transmission model is found by the torque converter ratio Figure 3 The parameters determine the torque ratio to be 2.2.

[0127] The engine model calculates the torque converter output torque by looking up the table to obtain the combustion torque of 200Nm through the engine speed and throttle opening:

[0128] Torque converter output torque = (200-25) x 2.2 = 385 Nm

[0129] Wheel end driving force = (385-12) x 4.044 x 3.683 / 0.31 = 17920.91 N

[0130] Engine speed at current speed 2 =385 / (0.9227x0.235^5)=582184, engine speed at current speed=763rmp.

[0131] Vehicle acceleration = (17920.91-153.54) / 1500 = 11.8449 m / s 2

[0132] The current speed of the vehicle = 0 + 11.8449 x 0.01 = 0.118449 m / s = 0.42642 km / h.

[0133] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and range of equivalents of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0134] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A vehicle system simulation model based on Simulink, characterized in that: include The driver inputs the model to provide the throttle opening and brake force required for the simulation process; The automatic gear shift model determines the gear position of the transmission based on the throttle opening and vehicle speed, and sends the vehicle gear position signal to the transmission system model; The engine model is input into the engine model a universal characteristic curve and a friction torque characteristic curve of the engine of the simulated vehicle, and the torque of the engine of the simulated vehicle is obtained by looking up a table according to the throttle opening input in the driver input model and the engine speed inversely calculated in the transmission system model; Transmission system model, including torque converter transmission model and gear transmission model, used to calculate wheel end driving force; The vehicle resistance model is used to simulate the vehicle resistance.

2. A method for operating a vehicle system simulation model based on Simulink according to claim 1, characterized in that: The method comprises the following steps: S1: setting model parameters according to the simulated vehicle and the simulated working conditions; S2: Run the simulation model; S3: Compare the simulation results with the experimental results.

3. The method according to claim 2, characterized in that: The S1 comprises the following steps: S101: Setting parameters of the driver input model; S102: Setting parameters of an automatic shifting model; S103: Setting parameters of the engine model; S104: Setting parameters of the transmission system model; S105: Setting parameters of the vehicle resistance model.

4. The method according to claim 3, characterized in that: The S104 comprises the following steps: S10401: Set the torque converter transmission model parameters and input the relationship between the hydraulic speed ratio and the torque ratio; S10402: Set the gear transmission model parameters, including the main reduction ratio, wheel radius, and speed ratio of each gear.

5. The method according to claim 2, characterized in that: The S2 comprises the following steps: S201: Select simulation frequency; S202: starting the simulation model, at which time the vehicle input speed is 0 km / h, and transmitting the input speed to the vehicle resistance model, the automatic shifting model, and the transmission system model respectively; S203: The vehicle resistance model calculates the current vehicle resistance by inputting the vehicle speed; S204: the automatic shift model determines the current gear position according to the input vehicle speed and the throttle opening in the driver input model, and transmits the gear position signal to the transmission system model; S205: The transmission system model calculates the engine speed and the wheel-end driving force according to the gear position signal and the input vehicle speed; S206: Calculate vehicle acceleration; S207: Calculate the current speed of the vehicle; S208: Substitute the current vehicle speed of S207 into the input vehicle speed of S202 and repeat S202-S206 until the preset time is up, thus completing the vehicle simulation.

6. The vehicle system simulation model based on Simulink according to claim 5, characterized in that: The calculation formula of the vehicle resistance F in S203 is as follows: F=Off 2 +Bv+C Where: v is the vehicle speed; A, B, and C are all constants and are determined by table lookup.

7. The vehicle system simulation model based on Simulink according to claim 5, characterized in that: The S205 comprises the following steps: S20501: Determine input speed and torque of the gear transmission model; When the automatic shift model outputs the gear position of 1st or 2nd gear, the torque converter transmission model calls the preset speed ratio and torque ratio curve to calculate the speed and torque of the torque converter turbine. Since the torque converter turbine is rigidly connected to the input shaft of the gear system, the speed and torque of the turbine are the input speed and torque of the gear transmission model. When the output gear of the automatic shift model is 3rd gear or higher, since the turbine and pump wheel of the torque converter are rigidly connected, the engine speed and torque are the input speed and torque of the gear transmission model; S20502: The gear transmission model selects a gear ratio according to the corresponding gear; S20503: Calculate the output speed and gear ratio of the torque converter transmission model; Gear transmission ratio = gear ratio × final reduction ratio Output speed of torque converter transmission model = gear ratio × input vehicle speed / (wheel radius × 2π) S20504: The torque converter transmission model calculates the torque converter speed ratio; Torque converter speed ratio = output speed of torque converter transmission model / engine speed at input vehicle speed S20505: The torque converter transmission model determines the torque ratio by looking up a map; S20506: The engine model calculates the torque converter output torque based on the engine speed and throttle opening: Torque converter output torque = (engine combustion torque - engine friction torque) × torque ratio S20507: The gear transmission model calculates the wheel end driving force based on the preset main reduction ratio, wheel radius, and gear transmission friction torque loss at different speeds: Wheel end driving force = (torque converter output torque - torque converter friction torque) × gear ratio × final reduction ratio / wheel radius; S20508: Calculate the engine speed at the current speed: Engine speed at current speed 2 = Torque converter output torque / (torque converter capacity factor × torque converter diameter 5 ).

8. The vehicle system simulation model based on Simulink according to claim 5, characterized in that: The vehicle acceleration calculation formula in S206 is as follows: Vehicle acceleration = (wheel end driving force - vehicle resistance) / vehicle mass.

9. The vehicle system simulation model based on Simulink according to claim 5, characterized in that: The current speed calculation formula of the vehicle in S207 is as follows: The current speed of the vehicle = input speed + vehicle acceleration × simulation frequency.

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