AMT creeping start control method based on load adaptive identification

Abstract

The application discloses an AMT creeping start control method based on load self-adaptive identification, which comprises the following steps: detecting the actual acceleration of the input rotating speed of one axis of the AMT by using a sensor, then comparing the actual acceleration with the set acceleration of the input rotating speed of the one axis, calculating the target position correction amount of the clutch combination in the next adjustment period, and controlling the clutch combination through closed-loop PID control. Thus, the vehicle can adjust the control parameters of the AMT transmission according to the actual load or the road slope change, so that the comfortable start effect is achieved, the riding experience of the driver and passengers is improved, and the method is suitable for normal creeping start working conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of automobile manufacturing, in particular to an AMT creeping start control method based on load self-adaptive identification. BACKGROUND

[0002] With the gradual development of automobile electronic technology and the acceleration of life rhythm, people prefer convenient and simple driving behavior. AMT transmission gradually enters the field of vision of people and is welcomed by the majority of users due to the characteristics of efficient automatic gear shifting, fuel saving and the like. The chassis of light vehicles is also diversified, and needs to match vehicle models with different loads, especially the development of the house car market. For the transmission, the control parameters of the entire transmission chain need to be changed accordingly when starting and shifting under different loads, so as to produce a comfortable starting process. In particular, for the creeping working condition, the load change of the whole vehicle directly affects the response time of the whole vehicle.

[0003] At present, the prediction of the load change of the whole vehicle is basically based on the longitudinal dynamics of the whole vehicle to estimate and predict the load of the whole vehicle, and the accuracy has limitations. In particular, under complex working conditions, the estimation effect of the estimation model deviates greatly from the actual load. Especially in the starting and creeping working condition, the vehicle gradually reaches a low speed from a standstill, and the acceleration of the whole vehicle changes in an impulsive manner, so the load predicted by the model is basically not reliable. Therefore, the control parameters of the AMT transmission need to be corrected according to the actual load or the change of the road slope, so as to obtain a comfortable starting effect and improve the riding experience of the driver and passenger, which is suitable for normal creeping start working conditions.

[0004] Through patent retrieval, the following patents have some relationship with the present application:

[0005] 1. Chinese Invention Patent No. 201510247378.6, Application Date: May 14, 2015, Publication No. CN104989815A, Publication Date: October 21, 2015, Name: "AMT Automatic Transmission Start Adaptive Control Method", Applicant: Wuhan Hekang Power Technology Co., Ltd.", the present application provides an AMT automatic transmission start adaptive control method for a public bus, which calculates the engine speed change rate, the main and driven shaft speed difference, the accelerator pedal speed change rate, and collects the engine speed, the clutch actual position, the throttle position, the clutch start to close setting time, the clutch target position, the clutch combination rate and the clutch half slip point position, so as to continuously adjust the current clutch half slip point until the requirement of fast and smooth start is met. However, the patent does not involve the technical problem of the difference in the starting process of the whole vehicle caused by the change of the load or the road slope.

[0006] 2. Chinese Invention Patent No. 201810991322.5, Application Date: 2018.08.29, Publication No. CN108869571A, Publication Date: 2018.11.23, Name: Clutch Combination Adaptive Control Method Based on Statistical Principle, Applicant: FAW Car Co., Ltd. This invention patent is related to a clutch combination adaptive control method based on statistical principle, which includes: dividing the difference between engine speed and gearbox input shaft speed into 5 speed difference bands during each clutch combination stage; recording the time from clutch contact to synchronization of gearbox input shaft speed and engine speed; calculating the percentage of time that the difference between engine speed and gearbox input shaft speed is located in each speed difference band; and obtaining the compensation coefficient for the next clutch combination stage. This invention obtains the compensation coefficient for the next clutch combination control by the difference between engine speed and gearbox speed during each clutch combination stage, automatically adapts to the change of clutch torque transmission characteristics, ensures the smoothness of clutch torque transmission, matches engine torque and clutch torque transmission, and ensures the smoothness of vehicle starting and shifting. However, this patent does not address the technical problem of differences in vehicle starting process caused by changes in load or road slope.

[0007] 3. Chinese Invention Patent No. 201910705430.6, Application Date: 2019.08.01, Publication No. CN110594317A, Publication Date: 2019.12.20, Name: Starting Control Strategy Based on Dual Clutch Automatic Transmission, Applicant: Chongqing University. This invention patent is related to a starting control strategy based on dual clutch automatic transmission, and the control steps are as follows: 1) Establish a power transmission model for the starting process of dual clutch automatic transmission; 2) Collect optimal starting process control strategy data from the power transmission model, and import the collected data into the adaptive fuzzy neural network toolbox to learn the control strategy of excellent drivers; 3) Use multi-objective particle swarm optimization algorithm to optimize the data learned by fuzzy neural network. This patent also does not address the technical problem of differences in vehicle starting process caused by changes in load or road slope.

[0008] 4. A Chinese invention patent with the application number "202210472977.8", the application date "2022.04.29", the publication number "CN115352445A", the publication date "2022.11.18", the name "AMT heavy-duty truck starting control method and system", and the applicant "Dongfeng Commercial Vehicle Co., Ltd.", which discloses an AMT heavy-duty truck starting control method and system. The engine target speed and the clutch target speed are set; the speed difference is determined according to the clutch target speed and the engine actual speed; the FF basic torque and the PI torque are determined based on the speed difference; the clutch target torque is determined according to the FF basic torque and the PI torque, and the clutch target displacement is controlled according to the clutch target torque, until the engine speed and the input shaft speed are synchronized to realize starting control. This patent also does not involve the technical problem of the difference in the starting process of the whole vehicle caused by the change of load or road slope.

[0009] 5. A Chinese invention patent with the application number "201911143463.2", the application date "2019.11.20", the publication number "CN111059269A", the publication date "2020.04.24", the name "Wet-type dual-clutch automatic transmission starting adaptive control method and vehicle", and the applicant "China First Automobile Co., Ltd.", which discloses a wet-type dual-clutch automatic transmission starting adaptive control method and vehicle. The wet-type dual-clutch automatic transmission starting adaptive control method collects the accelerator pedal position and the accelerator pedal position change rate as two input variables, outputs the engine target speed through the driver's intention fuzzy rule control table, then collects the engine actual speed, calculates the engine target speed difference and the engine target speed difference change rate, and takes them as input variables, outputs the clutch pressure change value through the starting fuzzy control rule, and then controls the clutch to increase the clutch pressure change value on the basis of the existing clutch pressure, fully considers the driver's starting control intention, and realizes the automatic control of the starting, and also adjusts the parameters of the fuzzy control rule online through the genetic algorithm, has the adaptive control function, and can meet the requirements of the smoothness and quickness of the starting process in different working conditions. This patent also does not involve the technical problem of the difference in the starting process of the whole vehicle caused by the change of load or road slope.

[0010] 6. Chinese invention patent with application number "202211360945.5", application date "2022.11.02", publication number "CN115649169A", publication date "2023.01.31", title "A Commercial Vehicle AMT Automatic Start Control Method", and applicant "Shaanxi Heavy-Duty Automobile Co., Ltd". This invention patent proposes an AMT automatic start control method for commercial vehicles, including a control state model and the jump conditions of the control state model. Through the coordinated control of the vehicle control system, transmission control system, engine control system and lever control system, when the vehicle is in D / R gear, the foot brake is released and the accelerator is not pressed, the transmission control system controls the clutch to automatically engage, and the vehicle drives stably at low speed. When the vehicle encounters steep slopes or other adverse conditions with high driving resistance, in order to avoid the risk of engine stalling, the clutch engagement depth is adjusted in real time to ensure the power response and driving smoothness of the vehicle in automatic start condition and enhance the driver's control performance. The patent also does not address the technical issues of differences in the vehicle's start-up process caused by variations in load or road slope. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to provide an AMT creep start control method based on load adaptive identification, which addresses the deficiencies in the existing technology.

[0012] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: an AMT creep start control method based on load adaptive identification, which calculates the target clutch engagement position for each adjustment cycle of the AMT based on the longitudinal dynamics model f(d,g(Δn,t)) of the test vehicle when it performs unloaded creep start on a standard test road surface. And the set acceleration of the input speed of the one-axis Then, the actual acceleration of the AMT's one-axis input speed is detected by the sensor. The actual acceleration of the input rotational speed of the shaft With the set acceleration of the input speed of one shaft By comparing the values, the target position correction (Δd) for clutch engagement in the next adjustment cycle is calculated, and the target position for clutch engagement in the next adjustment cycle is determined. Make corrections.

[0013] Furthermore, based on the set starting gear and driving style, the input speed of the primary shaft is determined. Functional relationship with time (t) (i represents gear 1, 2, R, and t represents time), and calculate the input speed of the primary shaft at different times.

[0014] Furthermore, the target position of clutch engagement is calculated according to the set clutch transmitted torque (T cl ), vehicle mass (M), gear (i), road slope (α) and rolling resistance coefficient (f) through a function relationship . In the formula: Δn is the rotational speed difference between the two ends of the clutch when the clutch is not fully engaged, i.e. the rotational speed difference between the engine speed and the input speed of the shaft, and t is time.

[0015] Further, a set of target positions of clutch engagement for achieving the set acceleration of the input speed of the shaft when starting at a fixed gear on a standard road surface under no load is obtained Further, the acceleration difference limit value of the input speed of the shaft is set When , the modified target position (d) of clutch engagement in the next adjustment period is calculated; when , the modification of the target position of clutch engagement is ended, and the input speed of the shaft (n in ) is compared with the engine speed (n en ); in the formula is the set input speed acceleration of the shaft in gear i, is the actual input speed acceleration of the shaft in gear i.

[0016] Further, the modified target position (d) of clutch engagement is calculated according to ; in the formula is the target position of clutch engagement at time j in gear i, is the actual position of clutch engagement at time j-1 in gear i, is the set acceleration of the input speed of the shaft at time j-1 in gear i, is the actual acceleration of the input speed of the shaft at time j-1 in gear i.

[0017] Further, when n in ≤n en -Δn lim , the comparison between and is continued, and the modified target position (d) of clutch engagement in the next adjustment period is calculated; in the formula n in is the current real-time input speed of the shaft, n en is the current engine speed, and Δn lim is the rotational speed difference limit for determining the synchronization of the input speed of the shaft (n in ) and the engine speed (n en ).

[0018] Further, when n in >n en -Δnlim When the clutch is fully engaged, the input speed of the first shaft (n in ) is synchronized with the engine speed (n en ).

[0019] Further, the engagement process of the clutch adopts closed-loop PID control.

[0020] The AMT creeping start control method based on load adaptive identification comprises the following steps:

[0021] S1: Obtain the temperature model of the dry clutch through bench test, Y temp =g(Δn, t);

[0022] S2: Obtain the torque transmission model of the dry clutch through bench test,

[0023] T cl =f(d, Y temp );

[0024] S3: Set the test vehicle to start at a certain fixed gear when creeping on a standard test road under no load, calculate the target position of clutch engagement during the start process according to

[0025] S4: Set a first shaft input speed acceleration difference limit value Use a first shaft speed sensor to detect the actual acceleration of the first shaft input speed When , correct the correction target position (d) of clutch engagement in the next adjustment period according to the calculation result of , control the clutch engagement through PID closed-loop control until is met;

[0026] S5: Compare the first shaft input speed (n in ) with the engine speed (n en ), when n in ≤n en -Δn lim , continue to calculate the correction target position (d) of clutch engagement in the next adjustment period and continue to correct the clutch engagement position in the next adjustment period; when n in >n en -Δn lim , the clutch is fully engaged, the first shaft input speed (n in ) is synchronized with the engine speed (n en ), and the AMT load adaptive identification creeping start process is completed. ​

[0027] The AMT creeping start control method based on load self-adaptive recognition has the advantages that the actual acceleration of the input rotation speed of the AMT is detected by using a sensor, and then compared with the set acceleration of the input rotation speed, so that the target position correction amount of the clutch combination in the next adjustment period is calculated, and the clutch combination is controlled through closed-loop PID control. Thus, the control parameters of the AMT transmission can be adjusted according to the actual load or the road slope change, so that comfortable start effect is achieved, the riding experience of the driver and passengers is improved, and the method is suitable for normal creeping start working conditions. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 AMT creeping start control method flow Figure 1 .

[0029] Figure 2 AMT creeping start control method flow Figure 2 . DETAILED DESCRIPTION

[0030] The application will be further described below by means of specific embodiments and in combination with the drawings:

[0031] The application is based on the longitudinal dynamics model of the whole vehicle, and the whole transmission chain structure of the AMT sample vehicle, and the transmission torque model and the clutch temperature model of the dry clutch are obtained by the test method in advance. The transmission torque capacity of the dry clutch is closely related to the temperature of the clutch plate, and the specific implementation steps of the application are as follows:

[0032] 1. First, based on the clutch friction plate matched with a certain vehicle model, the temperature model and the transmission torque model of the clutch are obtained by the bench test method:

[0033] Temperature model: Y temp = g (Δn, t)

[0034] In the formula, Δn is the rotation speed difference between the two ends of the clutch when the clutch is not fully combined, that is, the rotation speed difference between the engine rotation speed and the input rotation speed of the shaft, and t is time.

[0035] Transmission torque model:

[0036] In the formula, T cl is the torque transmitted at the end of the clutch, d is the position of the clutch, and Y temp is the temperature of the clutch.

[0037] 2. According to the matched vehicle model, the longitudinal dynamics model of the corresponding vehicle model is obtained, that is, the following motion balance model between the vehicle mass, the road slope and the vehicle longitudinal acceleration is obtained:

[0038]

[0039]

[0040] α f = arctan(f)

[0041]

[0042] where: is the vehicle longitudinal acceleration, is the input shaft speed acceleration, k i is the ratio of vehicle longitudinal acceleration to input shaft speed acceleration at i gear, M is the vehicle mass, I tr is the rotational inertia of the entire driveline from the input shaft end to the wheel end, J is the input shaft angular velocity acceleration, r g is the ratio of wheel radius to transmission ratio, F s is the brake force, F f is the air resistance, g is the gravitational acceleration, a is the slope, f is the rolling resistance coefficient, i tr is the transmission ratio, i z is the main reducer ratio, η T is the transmission efficiency, r c is the wheel radius.

[0043] Since the brake force F s is 0 during the starting process, and the starting speed is slow, the air resistance F f can be ignored, and further conversion can be obtained:

[0044]

[0045] Thus, we can get:

[0046]

[0047] Further, we can get:

[0048]

[0049] 3. Set different suitable rates of the input shaft speed change with time (n-t) according to different gears, i.e., set the function relationship between the input shaft speed and time during the crawl starting period:

[0050]

[0051] where: i represents the gear (1, 2, R), and Pi(t) is the set curve of the input shaft speed change with time, which is directly related to the starting gear and subjective evaluation style.

[0052] 4. Based on steps 2 and 3, the target engagement position of the clutch can be obtained at different times during the creep start of the test vehicle on a fixed standard test road surface, with a fixed gear (1, 2, or R) to achieve the set change curve of the primary shaft speed during the creep start process. This target engagement position is adaptively changed by the clutch at different times during the creep start process due to changes in the vehicle mass, road surface, and slope. The target position of a set of clutches is calculated at each moment until the primary shaft speed is completely synchronized with the engine speed, at which point the creep start process ends. The calculation is complete, as shown below:

[0053] At time t1: The unloaded mass is known to be M0, the road slope and rolling resistance are known, and the speed of the first axle is the set target value, i.e., T. cl It can be calculated that, based on the torque model, the target displacement of the clutch at different times can be calculated, i.e.:

[0054]

[0055] Where: n in Input the rotational speed of the current axis in real time. Let Δn be the engine speed at time t1+j. lim To determine the input speed (n) of one shaft in ) and engine speed (n en The limit of synchronous speed difference.

[0056] Therefore, we obtain a set of discrete points representing the clutch engagement target position during a fixed acceleration start-up process on a standard road surface under no-load conditions, in a specific gear (1, 2, or R), to achieve the target axle speed.

[0057]

[0058] 5. Based on the discrete set of clutch engagement points under standard road surface and standard load in step 4, the actual vehicle starting process is as follows:

[0059] At time t0: If the vehicle mass increases or the vehicle is going uphill, the starting calculation based on the standard discrete point set is as follows:

[0060]

[0061] If the calculation starts on a downhill slope using a standard discrete point set, the actual result is:

[0062]

[0063] Based on this, the present invention, at time t0, according to the target position The clutch engagement process employs closed-loop PID control (where the closed-loop control position accuracy error is: At this time, the actual position of the clutch is: The actual one-axis rotation speed acceleration of the whole vehicle is obtained by an axis rotation speed sensor The The set The next period clutch combination target position correction amount Δd is obtained by calculation, that is, the target position of clutch combination at the next period t1 (t1=t0+Δt, Δt is the TCU task scheduling period) is The clutch target position d control calculation of the whole AMT creeping starting process is as follows:

[0064] At t0 moment:

[0065] At t1 moment:

[0066] At t2 moment:

[0067]

[0068] At tj moment:

[0069]

[0070] In the formula: is the target position of clutch combination at i gear j moment, is the actual position of clutch combination at i gear j-1 moment, is the set acceleration of one-axis input rotation speed at i gear j-1 moment,

[0071] is the actual acceleration of one-axis input rotation speed at i gear j-1 moment.

[0072] The correction is gradually and sequentially corrected until the clutch is synchronized, and the starting process is ended, and the starting process control of the application is ended.

[0073] In summary, the beneficial effects of the present application are: the AMT creeping starting control method based on load adaptive identification of the present application detects the actual acceleration of one-axis input rotation speed of AMT by using a sensor, then compares it with the set acceleration of one-axis input rotation speed, calculates the target position correction amount of clutch combination in the next adjustment period, and controls the clutch combination by closed-loop PID control. Thus, the vehicle can adjust the control parameters of the AMT transmission according to the actual load or road slope change to achieve comfortable starting effect and improve the riding experience of the passengers, and is suitable for normal creeping starting working conditions.

[0074] The above examples are only for illustrating the present application, and are not limitation to the present application. Those skilled in the art can make various changes or transformations without departing from the spirit and scope of the present application. Therefore, all equivalent technical solutions should belong to the protection scope of the present application, and the protection scope of the present application should be defined by the claims.

Claims

1. An AMT creep start control method based on load adaptive identification, characterized in that: Includes the following steps: S1: Obtain the temperature model of the dry clutch through bench testing. ; S2: Obtain the torque transmission model of the dry clutch through bench testing. ; S3: Based on the test vehicle on a standard test road surface with known gradient and rolling resistance, a longitudinal dynamic model of the vehicle during unloaded creep start with known mass is generated. And the set acceleration of the input speed of the one-axis Calculate the target clutch engagement position for each adjustment cycle of the AMT. ; S4: Set the limit value of the input speed and acceleration difference of the single axis. The actual acceleration of the input speed of the single axis is detected by a single-axis speed sensor. ,when At that time, the target position for clutch engagement in the next adjustment cycle is corrected. The clutch engages through PID closed-loop control until the desired condition is met. until; S5: Input rotational speed to one shaft With engine speed In comparison, when Then, continue calculating the corrected target position for clutch engagement in the next adjustment cycle. And continue to correct the clutch engagement position for the next adjustment cycle, when At this time, the clutch is fully engaged, and the input speed of the first shaft is... With engine speed Synchronization, AMT load adaptive identification creep start process ends.

2. The AMT creep start control method based on load adaptive identification according to claim 1, characterized in that: Temperature model is In the formula The speed difference between the two ends of the clutch when the clutch is not fully engaged, that is, the speed difference between the engine speed and the input speed of the first shaft, where t is time.

3. The AMT creep start control method based on load adaptive identification according to claim 1, characterized in that: Torsional transmission model is In the formula, d represents the target position of clutch engagement.

4. The AMT creep start control method based on load adaptive identification according to claim 3, characterized in that: The clutch transmits torque in the torque transmission model In the formula: For one-axis input rotational speed and acceleration, This is the ratio of the vehicle's longitudinal acceleration to the acceleration due to the input rotational speed of the first axle when in gear i, where M is the vehicle's mass. Let be the moment of inertia of the entire transmission system from one shaft end to the wheel end, equivalent to the moment of inertia of one shaft end. This is the ratio of the wheel radius to the transmission ratio. It is the acceleration due to gravity. For slope, This is the rolling resistance coefficient.

5. The AMT creep start control method based on load adaptive identification according to claim 1, characterized in that: The longitudinal dynamics model of the whole vehicle is In the formula: For one-axis input rotational speed and acceleration, This is the ratio of the vehicle's longitudinal acceleration to the acceleration due to the input speed of the first axle when in gear i. For vehicle quality, Let be the moment of inertia of the entire transmission system from one shaft end to the wheel end, equivalent to the moment of inertia of one shaft end. This is the ratio of the wheel radius to the transmission ratio. It is the acceleration due to gravity. For slope, This is the rolling resistance coefficient.

6. The AMT creep start control method based on load adaptive identification according to any one of claims 1 to 5, characterized in that: according to Calculate the target position for clutch engagement; where The target position for clutch engagement at time j in gear i is given. This represents the actual position of the clutch engagement at time j-1 in gear i. The acceleration is the set acceleration for the input speed of the first shaft at time j-1 in gear i. The target position of clutch engagement during the starting process is calculated based on the actual acceleration of the input speed of the shaft at time j-1 in gear i.

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