Benchmarking correction method for automobile transmission system model and method for judging comfort

Abstract

The present application relates to a benchmarking correction method for an automobile transmission system model and a method for judging comfort, the benchmarking correction method comprising: performing a straight-line acceleration test on an actual vehicle to obtain a first vehicle speed-time variation relationship, a first engine torque-time variation relationship, and a first transmission gear-time variation relationship; establishing an initial automobile transmission system model; using a genetic algorithm to determine the optimal value of each coefficient in the initial automobile transmission system model; substituting the optimal value of each coefficient in the obtained parameter population into the initial automobile transmission system model to obtain a benchmarked and corrected automobile transmission system model. The automobile transmission system model can be obtained according to the acceleration test results of the actual vehicle, so that the benchmarked and corrected automobile transmission system model can be directly used to simulate the automobile straight-line acceleration and deceleration test in the future, without the need for the actual vehicle to perform relevant tests.

Description

Technical Field

[0001] The invention belongs to the field of automobile transmission system models, and in particular relates to a method for correcting a benchmark of an automobile transmission system model and a method for judging comfort. Background Art

[0002] In the process of developing automatic transmission vehicles, it is necessary to set up a gear shift logic that matches the vehicle. In order to adjust the appropriate gear shift logic, the existing method is to first set different gear shift logics for the actual vehicle, and then repeat the linear acceleration and deceleration tests on the actual vehicle for different gear shift logics to obtain relevant data, so as to adjust the gear shift logic and finally obtain a gear shift logic that meets comfort requirements.

[0003] During the above process, the driver is required to repeatedly drive the car for testing, which makes the driver feel extremely tired and may affect the driver's control of the car, thus causing unexpected dangers; each driving test takes a long time, which prolongs the time for adjusting the gear shifting logic and also prolongs the development cycle of automatic transmission cars; in addition, when the gear shifting logic is extremely mismatched, driving the actual vehicle for testing will cause great damage to the car's engine and transmission components, thereby generating additional maintenance costs. Summary of the invention

[0004] In view of this, the present invention provides a benchmarking correction method for an automobile transmission system model and a method for judging comfort, which can obtain a benchmarked and corrected automobile transmission system model corresponding to the actual vehicle according to the acceleration test results of the actual vehicle, so that the benchmarked and corrected automobile transmission system model can be directly used to simulate the automobile straight-line acceleration and deceleration test in the future without the need to perform relevant tests on the actual vehicle, thereby improving the safety of the process of obtaining relevant data, reducing the time for adjusting the gear shift logic, and avoiding the additional maintenance costs generated by the actual vehicle test.

[0005] The technical solution adopted by the present invention is:

[0006] A benchmarking correction method for an automobile transmission system model based on a genetic algorithm, wherein the automobile transmission system model is used to evaluate whether the automobile shifting logic meets the comfort requirement; the method comprises the following steps:

[0007] S100, performing a straight-line acceleration test on an actual vehicle, and collecting a first vehicle speed, a first torque output by an engine, and a first gear position of a transmission of the actual vehicle during the test, to obtain a time-varying relationship between the first vehicle speed, a time-varying relationship between the first engine torque, and a time-varying relationship between the first transmission gear position;

[0008] S200, establishing an initial vehicle transmission system model, wherein the initial vehicle transmission system model includes a correspondence between a driving wheel longitudinal force, a driven wheel longitudinal force and a vehicle speed; wherein the driving wheel longitudinal force is determined according to the engine torque, the transmission gear, the transmission ratio corresponding to the transmission gear and the transmission efficiency corresponding to the transmission gear, as well as the reducer transmission ratio and the transmission efficiency of the reducer; and the driven wheel longitudinal force F xf for:

[0009] F xf =Dsin(Carctan(Bx-E(Bx-arctan(Bx))));

[0010] Among them, B is the stiffness factor coefficient, C is the curve shape factor coefficient, D is the peak factor coefficient, E is the curve curvature factor coefficient, and x represents the slip rate of the driven wheel;

[0011] S300, using a genetic algorithm to determine the optimal value of each coefficient in the initial automobile transmission system model; wherein the parameter population in the genetic algorithm includes multiple groups of parameter groups, each of which includes coefficients B, C, D, and E; the fitness function and the termination condition are determined according to the simulated vehicle speed variation over time relationship output by the initial automobile transmission system model and the first vehicle speed variation over time relationship as a target when the first engine torque variation over time relationship and the first transmission gear variation over time relationship are used as inputs;

[0012] S400, substituting the optimized value of each coefficient in the parameter population obtained in step S300 into the initial vehicle transmission system model to obtain a benchmark-corrected vehicle transmission system model.

[0013] Preferably, in step S200, the initial automobile transmission system model is:

[0014]

[0015] Where n is the number of wheels on the front and rear axles, i(t) is the gear position i of the transmission at time t, g(i(t)) is the transmission ratio of the transmission at gear position i(t), τ(i(t)) is the transmission efficiency of the transmission at gear position i(t), T e (t) is the output torque of the engine at time t, g f is the transmission ratio of the reducer, η f is the transmission efficiency of the reducer, r w is the radius of the driving wheel, C d is the drag coefficient, ρ is the air density, A is the frontal area of ​​the car, V(t) is the simulated speed at time t in the car transmission system model, V w is the wind speed, m is the mass of the car, is the simulated acceleration at time t in the automobile transmission system model, g is the acceleration due to gravity, and β is the ramp angle.

[0016] Preferably, in step S300, each parameter group further includes a coefficient C d .

[0017] Preferably, in step S300, the coefficients B, C, D, E and C in the parameter population d The value range of is,

[0018] 5≤B≤50,1≤C≤10,1≤D≤10,0.5≤E≤5,0.2≤C d ≤0.4.

[0019] Preferably, in step S300, the fitness function is

[0020]

[0021] Where y is the number of simulation runs, S y is the total number of sampling times in the yth simulation, V(t) y is the simulated vehicle speed at time t output by the initial vehicle transmission system model during the yth simulation, and V(t)′ is the actual vehicle speed at time t in the first vehicle speed-time variation relationship.

[0022] Preferably, the termination condition is that MSE(y) is less than a preset value, and the preset value is 0-0.25.

[0023] Preferably, the step S300 includes the steps of:

[0024] S310, randomly generating an initial parameter population; wherein the initial parameter population includes N parameter groups, where N is greater than or equal to 20 and less than or equal to 50;

[0025] S320, taking each parameter group as an individual, taking the time variation relationship of the first engine torque and the time variation relationship of the first transmission gear as input to simulate the initial automobile transmission system model, obtaining the time variation relationship of the simulated vehicle speed of each individual, and calculating the fitness corresponding to each individual, wherein the fitness is a value obtained according to the fitness function;

[0026] S330, determine whether there is an individual that meets the termination condition, if yes, execute step S350; if no, execute step S340;

[0027] S340, selecting a preset number of individuals with the lowest fitness as parents, performing crossover and / or mutation to obtain a new parameter population, and returning to step S320;

[0028] S350, outputting the individuals satisfying the termination condition as a better parameter group, and determining the optimized values ​​of the coefficients in the initial automobile transmission system model according to the better parameter group.

[0029] Preferably, in step S350, when there are multiple individuals that meet the termination condition, the individual with the smallest fitness is used as the optimized value of each coefficient.

[0030] The present invention also provides a method for determining whether the gear shifting logic meets the comfort requirement by using the automobile transmission system model, comprising the steps of:

[0031] S10, using the aforementioned benchmarking correction method to obtain a benchmarked and corrected automobile transmission system model;

[0032] S20, obtaining a preset transmission gear position variation relationship over time and a plurality of corresponding second engine torque variation relationships over time; wherein the preset transmission gear position variation relationship over time is a function of the engine torque and the vehicle speed;

[0033] S30, using the plurality of second engine torque variation relationships over time and the preset transmission gear variation relationship over time as inputs of the benchmarked and corrected automobile transmission system model, to obtain a plurality of second vehicle speed variation relationships over time;

[0034] S40, obtaining a plurality of second jerk-time variation relationships according to a plurality of second vehicle speed-time variation relationships;

[0035] S50. Determine whether the jerk in each of the second jerk-versus-time relationships is within a set comfort range, and obtain the ratio of the number of second jerk-versus-time relationships that are always within the set comfort range to the total number of second jerk-versus-time relationships obtained in step S40; if the ratio is not less than a preset ratio, then the preset transmission gear position variation over time meets the comfort requirement.

[0036] Preferably, the step S50 further includes:

[0037] If the ratio is less than the preset ratio, the preset relationship between the transmission gear position and time does not meet the comfort requirement, and the preset relationship between the transmission gear position and time is adjusted, and then the process proceeds to step S20.

[0038] Beneficial effects of the present invention:

[0039] The present invention first establishes an initial automobile transmission system model and sets an initial parameter population, takes a first engine torque variation relationship over time and a first transmission gear variation relationship over time obtained from an actual vehicle straight-line acceleration test as inputs to the model, and takes a first vehicle speed variation relationship over time obtained from an actual vehicle test as a target output by the model, and performs benchmark correction on the initial automobile transmission system model. During the benchmark correction process, a suitable function is established based on the simulated vehicle speed variation relationship over time outputted by the initial automobile transmission system model each time and the target, and each coefficient of the initial automobile transmission system model is adjusted using a genetic algorithm, and the corresponding simulated vehicle speed variation relationship over time is repeatedly simulated until the simulated vehicle speed variation relationship obtained by simulating the initial automobile transmission model is close to the first vehicle speed variation relationship over time, thereby obtaining a benchmark-corrected automobile transmission system model. The automobile transmission system model thus obtained can simulate the actual vehicle driving conditions under other engine torque variation relationships and / or preset transmission gear variation relationships (shift logic). Therefore, in the vehicle transmission shift logic test, there is no need for the driver to conduct an actual vehicle driving test, thus avoiding the testing of actual vehicles with different shift logics and reducing the risk of accidents during the research and development process. Moreover, the use of the automobile transmission system model after benchmarking and correction can shorten the time for adjusting the shift logic compared to the actual vehicle test, thereby shortening the development cycle of automatic transmission vehicles. It can also avoid causing great damage to the engine and transmission components of the vehicle during the actual vehicle test when the shift logic is extremely mismatched, thereby further reducing the research and development cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The above and other objects, features and advantages of the present application will become more apparent through the following description of the embodiments of the present application with reference to the accompanying drawings, in which:

[0041] Figure 1 It is a flowchart of a benchmarking correction method of an automobile transmission system model based on a genetic algorithm of the present invention;

[0042] Figure 2 is a specific flow chart of step S300;

[0043] Figure 3 It is a flowchart of a method for using an automobile transmission system model to determine whether the shifting logic meets the comfort requirement of the present invention. DETAILED DESCRIPTION

[0044] The present application is described below based on embodiments, but the present application is not limited to these embodiments. In the detailed description of the present application below, some specific details are described in detail. In order to avoid confusing the essence of the present application, well-known methods, processes, procedures, and components are not described in detail.

[0045] In addition, persons of ordinary skill in the art will appreciate that the drawings provided herein are for illustration purposes and are not necessarily drawn to scale.

[0046] Unless the context clearly requires otherwise, throughout the specification and claims, the words "include", "comprising" and similar words should be interpreted in an inclusive sense rather than an exclusive or exhaustive sense; that is, in the sense of "including but not limited to".

[0047] In the description of this application, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of this application, unless otherwise specified, the meaning of "plurality" is two or more.

[0048] See also Figure 1 The present invention relates to a benchmarking correction method for an automobile transmission system model based on a genetic algorithm, wherein the automobile transmission system model is used to evaluate whether the automobile shifting logic conforms to comfort; the method comprises the steps of:

[0049] S100, performing a straight-line acceleration test on an actual vehicle, and collecting a first vehicle speed, a first torque output by an engine, and a first gear position of a transmission of the actual vehicle during the test, to obtain a time-varying relationship between the first vehicle speed, a time-varying relationship between the first engine torque, and a time-varying relationship between the first transmission gear position;

[0050] S200, establishing an initial vehicle transmission system model, wherein the initial vehicle transmission system model includes a correspondence between a driving wheel longitudinal force, a driven wheel longitudinal force and a vehicle speed; wherein the driving wheel longitudinal force is determined according to the engine torque, the transmission gear, the transmission ratio corresponding to the transmission gear and the transmission efficiency corresponding to the transmission gear, as well as the reducer transmission ratio and the transmission efficiency of the reducer; and the driven wheel longitudinal force F xf for:

[0051] F xf =Dsin(Carctan(Bx-E(Bx-arctan(Bx))));

[0052] Among them, B is the stiffness factor coefficient, C is the curve shape factor coefficient, D is the peak factor coefficient, E is the curve curvature factor coefficient, and x represents the slip rate of the driven wheel;

[0053] S300, using a genetic algorithm to determine the optimal value of each coefficient in the initial automobile transmission system model; wherein the parameter population in the genetic algorithm includes multiple groups of parameter groups, each of which includes coefficients B, C, D, and E; the fitness function and the termination condition are determined according to the simulated vehicle speed variation over time relationship output by the initial automobile transmission system model and the first vehicle speed variation over time relationship as a target when the first engine torque variation over time relationship and the first transmission gear variation over time relationship are used as inputs;

[0054] S400, substituting the optimized value of each coefficient in the parameter population obtained in step S300 into the initial vehicle transmission system model to obtain a benchmark-corrected vehicle transmission system model.

[0055] In step S100, the "actual vehicle" is a car that can be actually driven, the actual vehicle is an automatic transmission car, and the actual vehicle is a two-wheel drive car, such as a front-wheel drive car or a rear-wheel drive car. If it is a front-wheel drive car, the two front wheels are driving wheels and the two rear wheels are driven wheels; if it is a rear-wheel drive car, the two rear wheels are driving wheels and the two front wheels are driven wheels. The corresponding parameters of the hardware such as the appearance, engine, gearbox, reducer, tire, and transmission shaft of the actual vehicle are fixed. The "straight-line acceleration test" is the process in which the driver drives the actual vehicle to accelerate along a straight line, for example, the process in which the driver drives the actual vehicle along a straight line from 0km / h to the target speed, where the target speed can be 30km / h, 60km / h, 90km / h or 120km / h, etc.; in addition, during the straight-line acceleration test of the actual vehicle, the driver cannot actively brake the actual vehicle. The actual vehicle is equipped with relevant sensors, which can collect the engine torque (corresponding to the first torque), transmission gear (corresponding to the first gear) and actual vehicle speed (corresponding to the first vehicle speed) of the actual vehicle during the straight-line acceleration test in real time, so as to obtain the first engine torque variation relationship over time, the first transmission gear variation relationship over time and the first vehicle speed variation relationship over time. The "first engine torque variation relationship over time" describes the variation relationship of the output torque of the engine over time, and in one embodiment, it is a curve chart of the variation of the output torque of the engine over time; the "first transmission gear variation relationship over time" describes the variation relationship of the transmission gear over time, and in one embodiment, it is a square wave chart of the transmission gear variation over time; the "first vehicle speed variation relationship over time" describes the variation relationship of the actual vehicle speed over time, and in one embodiment, it is a curve chart of the actual vehicle speed variation over time.

[0056] Of course, the "straight-line acceleration test" process mentioned in the previous paragraph does not mean that the vehicle speed is always increasing during this process. It also includes the situation where the vehicle speed remains unchanged or decreases during driving. However, the speed reduction mentioned here refers to the reduction in speed when the driver does not actively brake, such as when the vehicle is climbing a slope.

[0057] In step S200, the initial vehicle transmission model can be used to simulate the relationship between the simulated vehicle speed and time when the vehicle is traveling in a straight line. Specifically, the initial vehicle transmission model can describe the corresponding relationship between the driving wheel longitudinal force, the driven wheel longitudinal force and the vehicle speed, wherein the driving wheel longitudinal force at time t can be expressed as F xr (t), the longitudinal force of the driven wheel is F xf , driven wheel longitudinal force F xf It can be expressed as:

[0058] F xf =Dsin(Carctan(Bx-E(Bx-arctan(Bx))))……………………(1)

[0059] Among them, B is the stiffness factor coefficient, C is the curve shape factor coefficient, D is the peak factor coefficient, E is the curve curvature factor coefficient, and x represents the slip rate of the driven wheel.

[0060] In formula (1), the specific value of x can be obtained from the internal package program of the simulation software MATLAB. In the package program, x is used as a variable and is related to the total longitudinal force (i.e., F x (t)), the vertical load on the driven wheel and the adhesion coefficient of the road surface (which can be obtained through detection and is a constant). Therefore, it can be determined based on the total longitudinal force in the model and the input adhesion coefficient.

[0061] In the initial automobile transmission system model, the driving wheel longitudinal force is determined according to the engine torque, the transmission gear, the transmission ratio corresponding to the transmission gear, the transmission efficiency corresponding to the transmission gear, and the reducer transmission ratio and the transmission efficiency of the reducer. In actual vehicles, the output shaft of the engine is connected to the input shaft of the transmission, the output shaft of the transmission is connected to the input shaft of the reducer, and the output shaft of the reducer is connected to the driving wheel. The reducer has a fixed transmission ratio and transmission efficiency, and each gear of the transmission also has its fixed transmission ratio and transmission efficiency. Therefore, the driving wheel longitudinal force F can be determined by the engine torque and the transmission gear. xr (t).

[0062] In step S300, in the initial automobile transmission system model, coefficients B, C, D, and E are coefficients to be optimized in the model. The present invention determines the optimized coefficient values ​​by simulating the initial automobile transmission system model based on a genetic algorithm. Multiple groups of parameter groups are generated in each simulation, and each parameter group contains specific values ​​of coefficients B, C, D, and E, which is equivalent to an individual described below. Therefore, multiple groups of outputs of the initial automobile transmission system model are obtained in each simulation. Specifically, in the entire simulation process, the inputs of the initial automobile transmission system model are the same, and the inputs are the time-varying relationship of the first engine torque and the time-varying relationship of the first transmission gear. Only the specific values ​​of the coefficients B, C, D, and E of different groups in each simulation and the same simulation are different. Therefore, the outputs of different groups in each simulation and the same simulation will also be different, but the outputs are the time-varying relationship of the simulated vehicle speed corresponding to each input. For example, in a simulation, a parameter group is substituted into the initial automobile transmission system model, and a corresponding output will be obtained. In this way, there will be several corresponding outputs for the several parameter groups in this simulation. Then, the fitness of each group is calculated according to the fitness function. If the fitness does not reach the termination condition, a new set of parameter groups is generated according to the genetic algorithm as the new parameter population in the next simulation, and the fitness corresponding to each parameter group is recalculated until the fitness that meets the termination condition appears. Among them, the fitness function is related to the output simulated vehicle speed change relationship over time and the first vehicle speed change relationship over time as the target. Since the first vehicle speed change relationship over time is the target and a fixed relationship, the fitness function can also be said to be a function of the output simulated vehicle speed change relationship over time; the termination condition can be related to the function value of the fitness function, such as setting the function value to meet a certain preset condition.

[0063] In step S400, the optimized values ​​of B, C, D, and E obtained in step S300 are substituted into the initial automobile transmission system model to obtain the automobile transmission system model after benchmarking and correction. In the later stage, the automobile transmission system model after benchmarking and correction can be used to simulate other engine torque variation relationships and other transmission gear variation relationships (which can be the shifting logic mentioned below) as input to obtain the simulated vehicle speed variation relationship. Therefore, when the engine torque variation relationship and the transmission gear transformation logic are adjusted each time, there is no need for the driver to obtain relevant test data (simulated vehicle speed variation relationship) by driving the actual vehicle, thereby avoiding the testing of the actual vehicle with different shifting logics and reducing the risk of accidents in the research and development process. Moreover, the use of the automobile transmission system model after benchmarking and correction can shorten the time for adjusting the shifting logic compared with the actual vehicle test, thereby shortening the development cycle of automatic transmission vehicles. It can also avoid great damage to the engine and transmission components of the vehicle during the actual vehicle test when the shifting logic is extremely mismatched, thereby further reducing the research and development cost.

[0064] Specifically, in step S200, the initial vehicle transmission system model can be represented by the following dynamic model:

[0065]

[0066] F x (t) = n(F xf +F xr (t))…………………………(3)

[0067]

[0068] Where: m is the mass of the car, is the simulated acceleration at time t in the vehicle transmission system model, F x (t) is the total longitudinal force on the vehicle at time t, F d (t) is the air resistance at time t, g is the acceleration due to gravity, β is the ramp angle, n is the number of wheels on the front and rear axles, and F xf is the longitudinal force of the driven wheel, F xr (t) is the longitudinal force of the driving wheel at time t, C d is the drag coefficient, ρ is the air density, A is the frontal area of ​​the car, V(t) is the simulated speed at time t in the car transmission system model, V w is the wind speed.

[0069] Wherein, formula (2) is obtained according to Newton's second law, which describes the relationship between the longitudinal force on the car model and its acceleration, wherein g is the acceleration due to gravity, which is a constant. In the initial car transmission system model and the car transmission system model after benchmarking and correction, the value of g remains unchanged; in the initial car transmission system model, β is the same as the ramp angle of the linear acceleration test in step S100, and in the car transmission system model after benchmarking and correction, β can be manually set according to actual needs; in the initial car transmission system model, the mass m is the same as the mass of the actual vehicle during the linear acceleration test in step S100, and in the car transmission system model after benchmarking and correction, since the number of drivers and passengers on the simulated car will change, the value of the mass m will change from the mass of the actual vehicle during the linear acceleration test, and thus the mass m can be manually set according to the state of the car to be simulated.

[0070] Formula (3) expresses the relationship between the total longitudinal force on the vehicle model and the longitudinal force of the driving wheel and the longitudinal force of the driven wheel. Usually, n is 2.

[0071] Formula (4) is the expression of air resistance. In the initial automobile transmission system model, air density ρ and wind speed Vw Same as the relevant data in step S100; in the benchmarked and corrected automobile transmission system model, the air density ρ and wind speed V w It can be set manually according to the actual simulation situation. The windward area A of the car is the windward area of ​​the actual vehicle, which is obtained after measuring the actual vehicle. The windward area A of the car is a constant. Drag coefficient C d It can be measured by testing the actual vehicle (wind tunnel test), C d is a constant.

[0072] By integrating formulas (2), (3) and (4), we can obtain:

[0073]

[0074] Substituting formula (1) into formula (5) yields:

[0075]

[0076]

[0077] Specifically, the initial vehicle transmission system model in step S200 includes an engine model, a transmission model and a reducer model. In the present invention, the engine model, the transmission model and the reducer model are used to represent the driving wheel longitudinal force F at time t. xr (t). Where:

[0078] The engine model is expressed as:

[0079] T e (t)…………………………………………(7)

[0080] T e (t) is the output torque of the engine at time t.

[0081] The transmission model is expressed as:

[0082] T t (t) = T t (g,τ,i)=g(i(t))·τ(i(t))·T e (t)………………(8)

[0083] Among them, T t (t) is the transmission output torque at time t, i(t) is the gear position i of the transmission at time t, g(i(t)) is the transmission ratio of the transmission at gear position i(t), and τ(i(t)) is the transmission efficiency of the transmission at gear position i(t).

[0084] The vehicle's transmission is an AT transmission or a DCT transmission, so the transmission has several fixed gears, and each gear has a corresponding, fixed transmission ratio and transmission efficiency. The transmission ratio and transmission efficiency of each gear can be obtained by collecting the transmission ratio and transmission efficiency of the transmission in the corresponding gear, or by referring to the transmission's own parameters (such as from the nameplate or manual of the reducer). Therefore, in the initial automobile transmission system model and the benchmarked and corrected automobile transmission system model, the transmission ratio and transmission efficiency of each gear of the transmission are constants.

[0085] The reducer model is expressed as:

[0086] T f (t) = T t (t) g f ·η f …………………………(9)

[0087] Among them, T f (t) is the output torque of the reducer at time t, g f is the transmission ratio of the reducer, η f is the transmission efficiency of the reducer.

[0088] The reducer has a fixed reducer transmission ratio g f and fixed reducer transmission efficiency η f , which can be collected when the reducer on the actual vehicle is running, or obtained from the reducer's own parameters (such as from the reducer's nameplate or manual). Therefore, in the initial vehicle transmission system model and the benchmarked and corrected vehicle transmission system model, the reducer transmission ratio g f and fixed reducer transmission efficiency η f are all constants.

[0089] The output shaft of the reducer is connected to the driving wheel, and the output torque of the reducer acts directly on the driving wheel. Therefore, the relationship between the longitudinal force of the driving wheel and time is expressed as:

[0090]

[0091] Among them, r w is the radius of the driving wheel.

[0092] Radius of driving wheel r w Obtained by measuring the radius of the driving wheel of the actual vehicle, r w is a constant (i.e., in the initial and benchmark-corrected vehicle transmission system models, r w The value remains unchanged).

[0093] After integrating formulas (7), (8), (9) and (10), we obtain:

[0094]

[0095] In formula (11), g f , η f and r w are known constants, so they can be obtained by inputting T e (t) and i(t) can be obtained by xr (t), so in step S200, the driving wheel longitudinal force can be determined according to the engine torque, the transmission gear, the transmission ratio corresponding to the transmission gear and the transmission efficiency corresponding to the transmission gear, as well as the reducer transmission ratio and the transmission efficiency of the reducer.

[0096] Substituting formula (11) into formula (6), the final initial vehicle transmission system model is:

[0097]

[0098] The relationship between acceleration and vehicle speed can be expressed as:

[0099]

[0100] Among them, V0 is the vehicle speed at time 0, that is, the initial speed of the vehicle.

[0101] In step S100, if the straight-line acceleration test is a process of accelerating from 0 km / h to the target vehicle speed, V0 in the initial vehicle transmission system model is 0 km / h. If the initial speed of the actual vehicle in the straight-line acceleration test is not 0 km / h, V0 in the initial vehicle transmission system model is the initial speed of the actual vehicle, which can be obtained by measurement and set in the initial vehicle transmission system model.

[0102] In the benchmark-corrected automobile transmission system model, V0 is a preset value, and the operator can set it independently according to the situation to be simulated.

[0103] In the initial transmission system model, in formulas (12) and (13), B, C, D, and E are unknown coefficients, and T e (t), i(t), V(t), and The coefficients B, C, D and E are determined by T in each simulation. e (t) inputs the time variation relationship of the first engine torque, i(t) inputs the time variation relationship of the first transmission gear, so as to obtain the time variation relationship of the simulated vehicle speed (i.e., the curve graph of the simulated vehicle speed from time 0 to the end time point).

[0104] Similarly, in the benchmarked modified vehicle transmission system model, the coefficients B, C, D and E have been determined, and the operator enters the pre-tested T e (t) and i(t) (where i(t) can be calculated based on the shift logic and T e (t) is determined), the relationship between the vehicle speed and time can be simulated.

[0105] Although the coefficient C d It can be obtained through wind tunnel test, but the cost of wind tunnel test is too high. In a preferred embodiment of the present invention, the coefficient C d It is also included in the coefficient of the parameter group, that is, in step S300, the parameter group also includes the coefficient C d , and then obtain the corresponding optimization value through the simulation process based on the genetic algorithm. At this time, in step S300, the parameter group also includes coefficients B, C, D, E and C d In step S400, B, C, D, E and C d The optimized value of is substituted into the initial vehicle transmission system model to obtain the benchmarked and corrected vehicle transmission system model.

[0106] Preferably, in step S300, the coefficients B, C, D, E and C in the parameter population d The value range is 5≤B≤50, 1≤C≤10, 1≤D≤10, 0.5≤E≤5, 0.2≤C d ≤0.4.

[0107] By limiting the value range of each coefficient, the number of generations of the genetic algorithm can be reduced, thereby shortening the time for obtaining a benchmark-corrected automobile transmission system model.

[0108] Preferably, in step S300, the fitness function is

[0109]

[0110] Where y is the number of simulation runs, S y is the total number of sampling times in the yth simulation, V(t) y is the simulated vehicle speed at time t output by the initial vehicle transmission system model during the yth simulation, and V(t)′ is the actual vehicle speed at time t in the first vehicle speed-time variation relationship.

[0111] The first engine torque at the corresponding time point in the relationship between the first engine torque and time is taken as T e (t), the first transmission gear position at the corresponding time point in the time-varying relationship of the first transmission gear position is input as i(t) to the initial vehicle transmission system model (B, C, D, E and C dThe specific value of is determined by the corresponding parameter group), so the relationship between the yth simulated vehicle speed and time can be output through the initial vehicle transmission system model, where the simulated vehicle speed at time t is V(t) y .

[0112] In step S100 , the first vehicle speed V′(t) at time t in the first vehicle speed-time variation relationship is obtained.

[0113] The fitness function can express the degree of discreteness of the relationship between the yth simulated speed change over time and the first speed change over time, which is achieved using the variance formula. That is to say, the lower the fitness value calculated by the fitness function, the closer the yth simulated speed change over time is to the first speed change over time, which means that the initial automobile transmission system model for deriving the yth simulated speed change over time is closer to the actual vehicle.

[0114] Of course, the fitness function can also be expressed as

[0115]

[0116] Preferably, the termination condition is that MSE(y) is less than a preset value, and the preset value is 0-0.25. The smaller the preset value is, the closer the final benchmark-corrected automobile transmission system model is to the actual vehicle. However, if the preset value is too small (the preset value is 0 or infinitely close to 0), the population generation of the genetic algorithm will be increased (see below for details), which will prolong the time to obtain the benchmark-corrected automobile transmission system model. Therefore, the preset value should be set reasonably. In the present invention, the preset value is preferably 0.03, 0.05, 0.07, 0.09, 0.1, 0.15, 0.2 or 0.25. Thereby, while ensuring that the benchmark-corrected automobile transmission system model is close to the actual vehicle, the time to obtain the benchmark-corrected automobile transmission system model can also be reduced.

[0117] Of course, the termination condition is that MSE(y) is less than a preset value, and the preset value is 0-0.3, such as 0.26, 0.27, 0.28, 0.29 or 0.3.

[0118] Preferably, see Figure 2 , the step S300 comprises the steps of:

[0119] S310, randomly generating an initial parameter population; wherein the initial parameter population includes N parameter groups, where N is greater than or equal to 20 and less than or equal to 50;

[0120] S320, taking each parameter group as an individual, taking the time variation relationship of the first engine torque and the time variation relationship of the first transmission gear as input to simulate the initial automobile transmission system model, obtaining the time variation relationship of the simulated vehicle speed of each individual, and calculating the fitness corresponding to each individual, wherein the fitness is a value obtained according to the fitness function;

[0121] S330, determine whether there is an individual that meets the termination condition, if yes, execute step S350; if no, execute step S340;

[0122] S340, selecting a preset number of individuals with the lowest fitness as parents, performing crossover and / or mutation to obtain a new parameter population, and returning to step S320;

[0123] S350, outputting the individuals satisfying the termination condition as a better parameter group, and determining the optimized values ​​of the coefficients in the initial automobile transmission system model according to the better parameter group.

[0124] In step S310, the randomly generated initial parameter population P0 includes N groups of parameter groups, that is, the initial parameter population P0 includes N individuals, each parameter group includes coefficients B, C, D, E and C d The specific value of , where the specific value of each coefficient is randomly selected within the corresponding value range.

[0125] In addition, if the coefficient C d The specific value of has been obtained through wind tunnel tests, and the parameter group includes the specific values ​​of coefficients B, C, D and E.

[0126] The parameter groups in the initial parameter population P0 are all different, that is, in the initial parameter population P0, among the coefficients in any two parameter groups, at least one coefficient has a different value.

[0127] The number of parameter groups in the initial parameter population P0 is 20-50, for example, 20, 25, 27, 30, 32, 35, 38, 40, 42, 45, 47, 50, etc., which provides a suitable number of samples. If the number of parameter groups is too small, the population generation of the genetic algorithm will increase, thereby slowing down the time for obtaining the benchmarked and corrected automobile transmission system model. If the number of parameter groups is too large, the time for simulation of each generation of the automobile transmission system model will increase, and the time for obtaining the benchmarked and corrected automobile transmission system model will also slow down the time for obtaining the benchmarked and corrected automobile transmission system model.

[0128] In step S320, each parameter group of the initial parameter population P0 is taken as an individual, so that the same number of individuals as the parameter groups can be obtained, and the values ​​of each coefficient in each individual are assigned to the initial vehicle transmission system model, so as to obtain the initial vehicle transmission system model corresponding to each individual one by one, and the first engine torque at the corresponding time point in the relationship between the first engine torque and time is taken as T e (t), the first transmission gear at the corresponding time point in the time relationship of the first transmission gear is input as i(t) to these initial vehicle transmission system models for simulation, so each initial vehicle transmission system model can output the simulated vehicle speed time relationship. Due to the differences between individuals, the simulated vehicle speed time relationship corresponding to the individuals is also different. The fitness of the simulated vehicle speed time relationship corresponding to each individual and the first vehicle speed time relationship is calculated respectively through the aforementioned fitness function.

[0129] In step S330, the fitness of each individual is compared with the termination condition to determine whether there is an individual that meets the termination condition.

[0130] For example, if the termination condition is set as MSE(y) less than 0.15, for a single individual, if the individual's fitness is less than 0.15, it means that the individual meets the termination condition; otherwise, if the individual's fitness is greater than or equal to 0.15, it means that the individual does not meet the termination condition.

[0131] In step S330, if there are individuals that meet the termination conditions, step S350 is executed, and "there are individuals that meet the termination conditions" means that there is at least one individual that meets the termination conditions; if there are no individuals that meet the termination conditions, step S340 is executed, and "no individuals that meet the termination conditions" means that all individuals do not meet the termination conditions.

[0132] In step S340, since no individual satisfying the termination condition is obtained in step S330, excellent individuals are selected according to the fitness of each individual. Here, excellent individuals can be judged by the fitness of each individual, that is, individuals with low fitness are better than individuals with high fitness. Therefore, a preset number of the best individuals can be screened out according to the fitness of each individual. The preset number is preferably 5-10. In actual application, the "preset number" can be set manually according to demand. For example, if the preset number is 5, the 5 individuals with the lowest fitness are screened out, and these 5 individuals are used as parents for crossover and / or mutation to obtain a new parameter population.

[0133] In addition, the specific values ​​of the coefficients in the parameter groups in the new parameter population are still limited by the aforementioned value ranges.

[0134] For example, there are 20 parameter groups in the initial parameter population P0, and the 20 individuals formed do not meet the termination condition. Therefore, in step S340, according to the fitness of these 20 individuals, the 5 individuals with the lowest fitness are selected as parents for crossover and / or mutation to obtain a new generation parameter population P1 (new parameter population). Then, the fitness of each individual of the new generation parameter population P1 is calculated through step S320, and it is judged through step S330 whether there are individuals that meet the termination condition. If there are still no individuals that meet the termination condition, a new second-generation parameter population P2 (new parameter population) is generated through step S340, and the above process is repeated until an individual that meets the termination condition is obtained.

[0135] In addition, in step S340, the number of parameter groups in the new parameter population is preferably equal to the number of parameter groups in the initial parameter population, or the number of parameter groups in the new parameter population may not be equal to the number of parameter groups in the initial parameter population, but the number of parameter groups in the new parameter population is still controlled within the range of 20-50.

[0136] When an individual that meets the termination condition appears in step S330, step S350 will be executed. In step S350, the individual that meets the termination condition can be directly output, and the parameter group corresponding to the individual that meets the termination condition is the optimal parameter group. The specific value of each coefficient in the optimal parameter group is the optimized value of each coefficient, so as to facilitate the benchmarking and correction of the automobile transmission system model in the subsequent step S400.

[0137] However, in some cases, when there are multiple individuals that meet the termination conditions at the same time, the individual with the smallest fitness is used as the optimized value of each coefficient.

[0138] See also Figure 3 The present invention also provides a method for determining whether the shifting logic meets the comfort requirement by using the automobile transmission system model, comprising the steps of:

[0139] S10, using the aforementioned benchmarking correction method to obtain a benchmarked and corrected automobile transmission system model;

[0140] S20, obtaining a preset transmission gear position variation relationship over time and a plurality of corresponding second engine torque variation relationships over time; wherein the preset transmission gear position variation relationship over time is a function of the engine torque and the vehicle speed;

[0141] S30, using the plurality of second engine torque variation relationships over time and the preset transmission gear variation relationship over time as inputs of the benchmarked and corrected automobile transmission system model, to obtain a plurality of second vehicle speed variation relationships over time;

[0142] S40, obtaining a plurality of second jerk-time variation relationships according to a plurality of second vehicle speed-time variation relationships;

[0143] S50. Determine whether the jerk in each of the second jerk-versus-time relationships is within a set comfort range, and obtain the ratio of the number of second jerk-versus-time relationships that are always within the set comfort range to the total number of second jerk-versus-time relationships obtained in step S40; if the ratio is not less than a preset ratio, then the preset transmission gear position variation over time meets the comfort requirement.

[0144] In the modified vehicle transmission system model, T e (t), i(t), V(t), and is an unknown state, B, C, D, E, C d ,x,g(i(t)),τ(i(t)),g f , η f 、r w , A and g are all fixed; m, ρ, β, V w and V0 are preset manually by the operator according to the actual needs of the simulation.

[0145] The following steps may be added between step S10 and step S20:

[0146] S11. Input m, ρ, β, V into the benchmarked and corrected vehicle transmission system model. w and the specific value of V0.

[0147] In addition, if the value of V0 is set to 0 by default, so that the vehicle transmission system model can only simulate the relationship between the simulated vehicle speed and time after starting from rest, then there is no need to input a specific value of V0 in step S11.

[0148] Right now:

[0149] S11. Input m, ρ, β and V into the benchmarked and corrected vehicle transmission system model. w Specific value.

[0150] Thus, after step S11, in the modified vehicle transmission system model, only T e (t), i(t), V(t), and In an unknown state, multiple second engine torque variation relationships over time and preset transmission gear variation relationships over time to be simulated can be input into the benchmark-corrected automobile transmission system model according to the vehicle driving state to be simulated. Each second engine torque variation relationship over time and the preset transmission gear variation relationship over time constitute an input group, thus forming a total of multiple input groups, and the multiple input groups are respectively input into the benchmark-corrected automobile transmission system model, so that multiple second vehicle speed variation relationships over time can be finally obtained. Among them, multiple second engine torque variation relationships over time and preset transmission gear variation relationships over time are artificially preset according to the vehicle driving state to be simulated.

[0151] The number of the second engine torque variation with time relationships may be 10-100, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100, etc., and the multiple second engine torque variation with time relationships are different.

[0152] In addition, the preset transmission gear position variation relationship over time is a function of the engine torque and the vehicle speed, i.e., the gear shifting logic; that is, by inputting the second engine torque variation relationship over time and the preset gear shifting logic into the benchmarked and corrected vehicle transmission system model, the second vehicle speed variation relationship over time can be output. Therefore, when the benchmarked and corrected vehicle transmission system model is actually applied to determine whether the gear shifting logic meets the comfort requirement, the vehicle transmission system model can be transformed. Specifically, the gear shifting logic is expressed as:

[0153] i(t)=i(T e (t),V(t))………………(16)

[0154] Therefore, the modified automobile transmission system model can be transformed into:

[0155]

[0156] Referring to formula (17), the automobile transmission system model consists of three interrelated formulas, among which T e (t), i(t), V(t), and There are four unknown variables, so once any one of them is confirmed, the other three variables can be obtained.

[0157] That is to say, in step S30, it is only necessary to input the second engine torque T at the corresponding time point into the vehicle transmission system model. e (t), we can get the second vehicle speed V(t) at time t, the second gear position i(t) of the transmission at time t, and the second acceleration at time t The set of V(t) at all times constitutes the second vehicle speed variation relationship over time. The collection of constitutes the second acceleration-time variation relationship.

[0158] Therefore, a plurality of second vehicle speed variation relationships over time and a plurality of second acceleration variation relationships over time can be obtained through the aforementioned plurality of input groups.

[0159] In step S40, the second vehicle speed versus time relationship is derived twice to obtain a second jerk versus time relationship, or the second acceleration versus time relationship is derived once to obtain a second jerk versus time relationship. The jerk at time t in the second jerk versus time relationship is represented as j(t), and the set of j(t) at all times constitutes the second jerk versus time relationship.

[0160] Each input group corresponds to a second jerk-versus-time variation relationship, and thus multiple second jerk-versus-time variation relationships can be obtained.

[0161] In step S50, it is determined whether the jerk in each second jerk-over-time relationship is within the set comfort range. If the jerk in a single second jerk-over-time relationship is within the comfort range (since the jerk in the vehicle's starting phase is outside the comfort range, the jerk in the starting phase may not be determined. The starting phase refers to a set time period after the vehicle speed starts from 0 km / h, and the set time period may be 0.7s-1.2s), it indicates that the second jerk-over-time relationship meets the comfort requirement. If a single second jerk-over-time relationship has a comfort level outside the comfort range, it indicates that the second jerk-over-time relationship does not meet the comfort requirement. The above determination is performed on each second jerk-over-time relationship, thereby obtaining the number N1 of second jerk-over-time relationships that meet the comfort requirement, and then obtaining the ratio of N1 to the total number N2 of second jerk-over-time relationships. If the ratio is not less than the preset ratio, it indicates that the aforementioned preset shift logic meets the comfort requirement.

[0162] The expression formula of the ratio can be expressed as:

[0163] The preset ratio is 80%-100%, for example, 80%, 85%, 90%, 95% or 100%.

[0164] The step S50 further includes:

[0165] If the ratio is less than the preset ratio, the preset relationship between the transmission gear position and time (the aforementioned shifting logic, formula (16)) does not meet the comfort requirement, and the preset relationship between the transmission gear position and time is adjusted, and then the process proceeds to step S20.

[0166] "Adjusting the relationship between the preset transmission gear position and time" means adjusting the preset shifting logic, and then re-verifying until a shifting logic that satisfies comfort is obtained.

[0167] The method provided by the present invention can be used to verify whether the preset shift logic meets the comfort requirements under the input conditions of multiple second engine torque variation relationships over time, and provide data support for obtaining a shift logic that meets the comfort requirements.

[0168] It should be understood that the above-mentioned embodiments are merely illustrative and not restrictive. Without departing from the basic principles of the present application, various obvious or equivalent modifications or substitutions that can be made by technicians in this field to the above details will be included in the scope of the claims of the present application.

Claims

1. A benchmarking correction method for a vehicle transmission system model based on a genetic algorithm, wherein the vehicle transmission system model is used to evaluate whether the vehicle shifting logic meets the comfort requirement; characterized in that: Includes steps: S100, performing a straight-line acceleration test on an actual vehicle, and collecting a first vehicle speed, a first torque output by an engine, and a first gear position of a transmission of the actual vehicle during the test, to obtain a time-varying relationship between the first vehicle speed, a time-varying relationship between the first engine torque, and a time-varying relationship between the first transmission gear position; S200, establishing an initial vehicle transmission system model, wherein the initial vehicle transmission system model includes a correspondence between a driving wheel longitudinal force, a driven wheel longitudinal force and a vehicle speed; wherein the driving wheel longitudinal force is determined according to the engine torque, the transmission gear, the transmission ratio corresponding to the transmission gear and the transmission efficiency corresponding to the transmission gear, as well as the reducer transmission ratio and the transmission efficiency of the reducer; and the driven wheel longitudinal force F xf for: F xf =Dsin(Carctan(Bx-E(Bx-arctan(Bx)))); Among them, B is the stiffness factor coefficient, C is the curve shape factor coefficient, D is the peak factor coefficient, E is the curve curvature factor coefficient, and x represents the slip rate of the driven wheel; S300, using a genetic algorithm to determine the optimal value of each coefficient in the initial automobile transmission system model; wherein the parameter population in the genetic algorithm includes multiple groups of parameter groups, each of which includes coefficients B, C, D, and E; the fitness function and the termination condition are determined according to the simulated vehicle speed variation over time relationship output by the initial automobile transmission system model and the first vehicle speed variation over time relationship as a target when the first engine torque variation over time relationship and the first transmission gear variation over time relationship are used as inputs; S400, substituting the optimized value of each coefficient in the parameter population obtained in step S300 into the initial vehicle transmission system model to obtain a benchmark-corrected vehicle transmission system model.

2. The method according to claim 1, characterized in that In step S200, the initial automobile transmission system model is: Where n is the number of wheels on the front and rear axles, i(t) is the gear position i of the transmission at time t, g(i(t)) is the transmission ratio of the transmission at gear position i(t), τ(i(t)) is the transmission efficiency of the transmission at gear position i(t), T e (t) is the output torque of the engine at time t, g f is the transmission ratio of the reducer, η f is the transmission efficiency of the reducer, r w is the radius of the driving wheel, C d is the drag coefficient, ρ is the air density, A is the frontal area of ​​the car, V(t) is the simulated speed at time t in the car transmission system model, V w is the wind speed, m is the mass of the car, is the simulated acceleration at time t in the vehicle transmission system model, g is the acceleration due to gravity, and β is the ramp angle.

3. The method according to claim 2, characterized in that In step S300, each parameter group also includes a coefficient C d .

4. The method according to claim 3, characterized in that In step S300, the coefficients B, C, D, E and C in the parameter population d The value range of is, 5≤B≤50,1≤C≤10,1≤D≤10,0.5≤E≤5,0.2≤C d ≤0.4。 5. The method according to any one of claims 1 to 4, characterized in that: In step S300, the fitness function is Where y is the number of simulation runs, S y is the total number of sampling times in the yth simulation, V(t) y is the simulated vehicle speed at time t output by the initial vehicle transmission system model during the yth simulation, and V(t)′ is the actual vehicle speed at time t in the first vehicle speed-time variation relationship.

6. The method according to claim 5, characterized in that The termination condition is that MSE(y) is less than a preset value, and the preset value is 0-0.

25.

7. The method according to any one of claims 1 to 6, characterized in that: The step S300 includes the following steps: S310, randomly generating an initial parameter population; wherein the initial parameter population includes N parameter groups, where N is greater than or equal to 20 and less than or equal to 50; S320, taking each parameter group as an individual, taking the time variation relationship of the first engine torque and the time variation relationship of the first transmission gear as input to simulate the initial automobile transmission system model, obtaining the time variation relationship of the simulated vehicle speed of each individual, and calculating the fitness corresponding to each individual, wherein the fitness is a value obtained according to the fitness function; S330, determine whether there is an individual that meets the termination condition, if yes, execute step S350; if no, execute step S340; S340, selecting a preset number of individuals with the lowest fitness as parents, performing crossover and / or mutation to obtain a new parameter population, and returning to step S320; S350, outputting the individuals satisfying the termination condition as a better parameter group, and determining the optimized values ​​of the coefficients in the initial automobile transmission system model according to the better parameter group.

8. The method according to claim 7, characterized in that In step S350, when there are multiple individuals that meet the termination condition, the individual with the smallest fitness is used as the optimized value of each coefficient.

9. A method for determining whether the gear shifting logic meets the comfort requirement by using a vehicle transmission system model, characterized in that: Includes steps: S10, using the benchmarking correction method according to any one of claims 1 to 8 to obtain a benchmarked and corrected automobile transmission system model; S20, obtaining a preset transmission gear position variation relationship over time and a plurality of corresponding second engine torque variation relationships over time; wherein the preset transmission gear position variation relationship over time is a function of the engine torque and the vehicle speed; S30, using the plurality of second engine torque variation relationships over time and the preset transmission gear variation relationship over time as inputs of the benchmarked and corrected automobile transmission system model, to obtain a plurality of second vehicle speed variation relationships over time; S40, obtaining a plurality of second jerk-time variation relationships according to a plurality of second vehicle speed-time variation relationships; S50. Determine whether the jerk in each of the second jerk-versus-time relationships is within a set comfort range, and obtain the ratio of the number of second jerk-versus-time relationships that are always within the set comfort range to the total number of second jerk-versus-time relationships obtained in step S40; if the ratio is not less than a preset ratio, then the preset transmission gear position variation over time meets the comfort requirement.

10. The method according to claim 9, characterized in that The step S50 further includes: If the ratio is less than the preset ratio, the preset relationship between the transmission gear position and time does not meet the comfort requirement, and the preset relationship between the transmission gear position and time is adjusted, and then the process proceeds to step S20.

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