Acceleration-based vehicle speed limit control method and system and vehicle

Abstract

The invention discloses a vehicle speed limiting control method and system based on acceleration and a vehicle. The vehicle speed limiting control method comprises the steps that S1, the corresponding relation between the vehicle acceleration and the vehicle speed intervening in a threshold during vehicle speed limiting is obtained; s2, determining a vehicle speed limit value, and monitoring the current acceleration and speed value of the vehicle in real time; s3, an intervention threshold vehicle speed corresponding to the current acceleration value is determined, and a first vehicle speed difference value between the vehicle speed limit value and the intervention threshold vehicle speed is obtained; s4, the first vehicle speed difference value is compared with the current vehicle speed value, and the current vehicle driving mode is determined; s5, if the vehicle enters the vehicle speed limiting mode, an acceleration target curve that the current intervention threshold vehicle speed slowly approaches the vehicle speed limiting value is obtained; and S6, based on the target vehicle speed in the acceleration target curve, carrying out following control of the target vehicle speed on the current actual vehicle speed of the vehicle. According to the technical scheme, the vehicle speed can be controlled to slowly approach but not exceed the maximum limit value, and the vehicle running stability is guaranteed while the speed limiting requirement is met.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle speed control, and more specifically, to a vehicle speed limit control method, system and vehicle based on acceleration. Background Art

[0002] In recent years, with the rapid development of the automobile industry, vehicles have become more and more popular in people's daily lives. In order to ensure driving safety and comply with road traffic regulations, it is usually necessary to control the speed of the vehicle during driving. For example, on speed-limited roads, drivers usually need to control the speed of the vehicle to ensure that the vehicle meets the speed requirements of road traffic regulations.

[0003] At present, when a vehicle accelerates in normal acceleration mode, the vehicle's driving torque usually increases with the increase of the throttle opening, and the vehicle speed will also increase rapidly, with the risk of speed overshoot. In order to meet the speed limit requirements, traditional methods usually force the output torque peak to be limited. At this time, although the vehicle's driving speed will be reduced, the sudden change in vehicle torque will inevitably affect the vehicle's driving smoothness and stability. In severe cases, the vehicle will also experience torque shock and driving frustration, affecting the vehicle's drivability.

[0004] Therefore, how to provide an acceleration-based speed limit control method, control system and vehicle, which can control the vehicle speed to slowly approach but not exceed the maximum limit, meet the speed limit requirements while ensuring the stability of vehicle operation, has become a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the invention

[0005] To solve the above technical problems, the present invention provides a vehicle speed limit control method, a control system and a vehicle based on acceleration, which can control the vehicle speed to slowly approach but not exceed the maximum limit, thereby meeting the speed limit requirements while ensuring the stability of vehicle operation.

[0006] The technical solution provided by the present invention is as follows:

[0007] The present invention provides a vehicle speed limit control method based on acceleration, comprising the following steps: S1, obtaining the corresponding relationship between the vehicle acceleration and the intervention threshold vehicle speed when the vehicle is speed-limited through actual vehicle calibration; S2, determining the vehicle speed limit, configuring the vehicle normal acceleration mode and the vehicle speed limit mode, and then monitoring the current acceleration and speed value of the vehicle in real time; S3, determining the intervention threshold vehicle speed corresponding to the current acceleration value according to the corresponding relationship and the current acceleration value, and obtaining a first vehicle speed difference between the vehicle speed limit and the intervention threshold vehicle speed; S4, comparing and analyzing the first vehicle speed difference with the current vehicle speed value to determine the current driving mode of the vehicle;

[0008] S5. If the vehicle currently enters the speed limit mode, then a first-order low-pass filter is used to obtain an acceleration target curve that slowly approaches the speed limit from the current intervention threshold speed; S6. Based on the target speed in the acceleration target curve, the current actual vehicle speed is controlled to follow the target speed to achieve the actual vehicle speed slowly approaching the speed limit.

[0009] Furthermore, in a preferred embodiment of the present invention, in step S4, the comparative analysis step includes:

[0010] S401, obtaining the first vehicle speed difference and the current vehicle speed value;

[0011] S402, performing a difference operation on the first vehicle speed difference and the current vehicle speed value to obtain a second vehicle speed difference, and setting a difference comparison threshold;

[0012] S403, comparing and analyzing the second vehicle speed difference with the difference comparison threshold;

[0013] S404. If the second vehicle speed difference is greater than the difference comparison threshold, the vehicle is in a normal acceleration state, and the vehicle is determined to enter the normal acceleration mode, and jump back to step S2 to continue to monitor the current acceleration and speed value of the vehicle in real time; if the second vehicle speed difference is less than the difference comparison threshold, it is determined that the vehicle enters the speed limit mode.

[0014] Furthermore, in a preferred embodiment of the present invention, step S5 comprises:

[0015] S501: If it is determined that the vehicle currently enters the speed limit mode;

[0016] S501, then obtain the first-order filter characteristic equation: Y n =(1-A)X n +A*Y n-1 , where Y n For the control object, X n is the control object limit, Y n-1 is the control object in the previous state, A is the filter coefficient;

[0017] S502, then determining a filter coefficient A according to the current acceleration value of the vehicle;

[0018] S503. Finally, based on the vehicle speed limit and the vehicle speed value, an acceleration target curve is set, and an acceleration target curve equation is obtained: V n =(1-A)V tc +A*V n-1 , where V n is the target vehicle speed, V tc is the speed limit, Vn-1 is the target vehicle speed at the previous moment.

[0019] Furthermore, in a preferred embodiment of the present invention, step S6 comprises:

[0020] S601, based on the acceleration target curve, obtaining a target vehicle speed corresponding to the vehicle in a speed limit mode;

[0021] S602, adjusting the vehicle transmission input control torque through feedforward and PI control, limiting the actual vehicle speed, and performing a tracking control on the actual vehicle speed to the target speed;

[0022] S603, monitoring the actual speed of the vehicle in real time;

[0023] S604: Obtain a third vehicle speed difference between the actual vehicle speed and the corresponding target vehicle speed, and perform deviation control on the third vehicle speed difference so that the actual vehicle speed slowly approaches the vehicle speed limit.

[0024] Furthermore, in a preferred embodiment of the present invention, step S602 includes:

[0025] S602.1. Obtain the vehicle running resistance and based on air resistance, tire rolling resistance and ramp resistance;

[0026] S602.2. Calculate the transmission input torque by combining the vehicle parameter information and the vehicle running resistance:

[0027] T' tq =∑F*r / (i g ×i0×η)=(F f +F w +F i )*r / (i g ×i0×η)

[0028] =(mg*f+C d *A*V 2 / 21.15+mg*sinα)*r / (i g ×i0×η)

[0029] Among them, F f is the tire rolling resistance, F w is air resistance, F i is the slope resistance, m is the vehicle weight, g is the acceleration of gravity, f is the rolling resistance coefficient, C d is the air resistance coefficient, A is the frontal area of ​​the vehicle, α is the slope inclination, i g is the transmission ratio, i0 is the main reduction ratio, η is the transmission efficiency, and r is the tire radius;

[0030] S602.3, set the proportional coefficient K p And the integration coefficient K i , combined with the third vehicle speed difference e(t), the proportional part and the integral part of the wheel end driving force U(t) are obtained respectively through PI control:

[0031] Proportional part U(t) = K p e(t),

[0032]

[0033] S602.4. Obtain torque correction value ΔT according to the wheel end driving force U(t) tq :

[0034]

[0035] S602.5. Calculate the transmission input control torque by combining the transmission input torque and the torque correction value:

[0036]

[0037] Further, in a preferred embodiment of the present invention, the step S604 includes:

[0038] S604.1. Monitor the third vehicle speed difference in real time;

[0039] S604.2. Set a first deviation range value, a second deviation range value, and a third deviation range value;

[0040] S604.3. When the actual vehicle speed approaches the target vehicle speed, the transmission input control torque is controlled in different regions according to the deviation range value.

[0041] Furthermore, in a preferred embodiment of the present invention, in step S604.3, the sub-region control is specifically:

[0042] When the actual speed of the vehicle is within the first deviation range of the target speed, integral holding is implemented, and the integral term in the transmission input control torque expression The output results are no longer accumulated;

[0043] When the actual vehicle speed is within the second deviation range of the target speed, the integral part is cleared and the transmission input control torque is adjusted:

[0044] T tq =(mg*f+C d *A*V 2 / 21.15+mg*sinα+K p·e(t))*r / (i g ×i0×η);

[0045] When the actual vehicle speed is within the third deviation range of the target speed, the feedforward, proportional part and integral part are cleared, and the transmission input control torque is adjusted: T tq =0;

[0046] When the actual vehicle speed is within other deviation ranges of the target vehicle speed, the transmission input control torque is adjusted in a normal state.

[0047] Further, in a preferred embodiment of the present invention, the first deviation range value is specifically ±1km / h, the second deviation range value is specifically greater than 1km / h and less than 3km / h, and the third deviation range value is specifically greater than 3km / h.

[0048] The present invention also provides a vehicle speed limit control system based on acceleration, comprising:

[0049] An intervention threshold speed determination module is used to determine the corresponding relationship between the vehicle acceleration and the intervention threshold speed when the vehicle speed is limited based on the vehicle accelerometer through real vehicle calibration data;

[0050] A speed limit acquisition module is used to determine the speed limit according to the current state of the vehicle and chart data;

[0051] Vehicle speed monitoring module, used to monitor the vehicle's current acceleration and speed in real time;

[0052] A vehicle speed difference calculation module, used to determine an intervention threshold vehicle speed corresponding to the current acceleration value according to the vehicle's current acceleration value, and obtain a first vehicle speed difference between the vehicle speed limit and the intervention threshold vehicle speed;

[0053] A driving mode configuration module, configured to configure a normal acceleration mode or a speed limit mode for the vehicle, compare and analyze the first vehicle speed difference with the current speed value of the vehicle, and determine the current driving mode of the vehicle;

[0054] A vehicle speed target curve calculation module, which obtains an acceleration target curve that slowly approaches the vehicle speed limit from the current intervention threshold vehicle speed through a first-order low-pass filter;

[0055] A vehicle speed following control module, used to adjust the vehicle transmission input control torque according to the target vehicle speed in the acceleration target curve, and perform following control on the target vehicle speed for the current actual vehicle speed;

[0056] The vehicle speed deviation control module is used to perform deviation control on the actual vehicle speed and its corresponding target vehicle speed.

[0057] In addition, the present invention also provides a vehicle, comprising the acceleration-based vehicle speed limit control system.

[0058] The present invention provides a vehicle speed limit control method based on acceleration, a control system and a vehicle, the vehicle speed limit control method comprising the following steps: S1, obtaining the corresponding relationship between the vehicle acceleration and the intervention threshold speed when the vehicle is speed limited through actual vehicle calibration; S2, determining the speed limit, configuring the normal acceleration mode and the speed limit mode of the vehicle, and then monitoring the current acceleration and speed value of the vehicle in real time; S3, determining the intervention threshold speed corresponding to the current acceleration value according to the corresponding relationship and the current acceleration value, and obtaining the first vehicle speed difference between the speed limit and the intervention threshold speed; S4, comparing and analyzing the first vehicle speed difference with the current speed value of the vehicle to determine the current driving mode of the vehicle; S5, if the vehicle currently enters the speed limit mode, then obtaining an acceleration target curve that slowly approaches the speed limit from the current intervention threshold speed through a first-order low-pass filter; S6, based on the target speed in the acceleration target curve, performing the target speed tracking control on the current actual vehicle speed, and the actual vehicle speed slowly approaches the speed limit.For the acceleration-based speed limit control method disclosed in the present invention, the method flow mainly includes six steps: first, the actual vehicle needs to be calibrated to obtain a corresponding relationship table between the vehicle acceleration and the intervention threshold speed when the vehicle is speed limited. The intervention threshold speed is the actual vehicle speed corresponding to the speed limit intervention of the vehicle in order to eliminate the risk of vehicle speed overshoot. The intervention threshold speed is associated with the current acceleration of the vehicle. The higher the acceleration, the lower the intervention threshold speed when the speed limit control is started; then, the speed limit value of the vehicle when driving is obtained through vehicle chart data, and the normal acceleration mode and the speed limit mode are configured for the vehicle during the driving process, and the vehicle acceleration and speed value are monitored in real time. In the normal acceleration mode, the vehicle responds to the accelerator pedal output control and outputs torque according to the transmission input torque setting corresponding to the accelerator pedal. In the speed limit mode, the transmission input torque no longer responds to the accelerator pedal signal, and is input according to the torque value corresponding to the closed-loop control of the target speed; then, the corresponding acceleration value is determined according to the acceleration value obtained in real time. The intervention threshold speed is determined, and the intervention threshold speed is calculated as a difference between the intervention threshold speed and the speed limit to obtain the first speed difference; then the current speed value of the vehicle is compared with the first speed difference in real time to determine whether the vehicle has entered the speed limit mode. If it is determined that the vehicle has entered the speed limit mode, the next step is performed, otherwise the vehicle accelerates according to the normal acceleration mode, and the vehicle acceleration and speed value are continuously monitored in real time; when it is determined that the vehicle has entered the speed limit mode, a first-order low-pass filtering method is immediately used to define an acceleration target curve that slowly approaches the speed limit from the intervention threshold speed, and the filter coefficient in the acceleration target curve is a function of acceleration. When entering the speed limit mode, the greater the acceleration of the vehicle, the greater the filter coefficient, and the more gently the corresponding acceleration target curve rises; finally, in the speed limit mode, based on the target speed in the acceleration target curve, the vehicle adopts feedforward plus PI control to achieve the following of the actual vehicle speed and the target speed, so that the actual vehicle speed slowly approaches the speed limit, thereby ensuring the stability of the vehicle. It can be seen that, compared with the prior art, the technical solution involved in the present invention can control the vehicle speed to slowly approach but not exceed the maximum limit, thereby meeting the speed limit requirements while ensuring the stability of the vehicle operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0060] Figure 1is a flowchart of the steps of the acceleration-based vehicle speed limit control method involved in an embodiment of the present invention;

[0061] Figure 2 It is a schematic diagram of the acceleration process of the vehicle according to the normal acceleration mode involved in the embodiment of the present invention;

[0062] Figure 3 A schematic diagram of the relationship between the vehicle speed advance intervention amount and acceleration involved in an embodiment of the present invention;

[0063] Figure 4 It is a schematic diagram of the acceleration process of the vehicle according to the normal acceleration mode and the speed limit mode involved in the embodiment of the present invention;

[0064] Figure 5 A schematic diagram of a process of a vehicle entering the speed limit mode according to an embodiment of the present invention;

[0065] Figure 6 A schematic diagram of a process in which a vehicle according to an embodiment of the present invention accelerates according to an acceleration target curve;

[0066] Figure 7 The present invention is a flowchart of the steps of controlling the current actual vehicle speed to follow the target vehicle speed according to an embodiment of the present invention. DETAILED DESCRIPTION

[0067] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0068] It should be noted that when an element is referred to as being "fixed on" or "set on" another element, it can be directly on the other element or indirectly set on the other element; when an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0069] It should be understood that the terms "length", "width", "up", "down", "front", "back", "first", "second", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0070] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" and "several" is two or more, unless otherwise clearly and specifically defined.

[0071] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical contents disclosed by the present invention.

[0072] Please Figures 1 to 7 As shown, the present invention provides a speed limit control method, control system and vehicle based on acceleration. In the speed limit control method, when the vehicle speed approaches the speed limit, the speed limit mode is entered, and the vehicle speed can be controlled to slowly approach but not exceed the maximum limit, thereby meeting the speed limit requirement and ensuring the stability of the vehicle during operation. The acceleration-based speed limit control method includes the following steps: S1. Obtaining the corresponding relationship between the vehicle acceleration and the intervention threshold speed when the vehicle is speed limited through actual vehicle calibration; S2. Determining the speed limit, configuring the vehicle's normal acceleration mode and speed limit mode, and then monitoring the vehicle's current acceleration and speed value in real time; S3. Determining the intervention threshold speed corresponding to the current acceleration value based on the corresponding relationship and the current acceleration value, and obtaining the first speed difference between the speed limit and the intervention threshold speed;

[0073] S4. Compare and analyze the first speed difference with the current speed value of the vehicle to determine the current driving mode of the vehicle; S5. If the vehicle currently enters the speed limit mode, then obtain the acceleration target curve from the current intervention threshold speed slowly approaching the speed limit through a first-order low-pass filter; S6. Based on the target speed in the acceleration target curve, the current actual vehicle speed is controlled to follow the target speed to achieve the actual vehicle speed slowly approaching the speed limit. The technical solution involved in the present invention can control the vehicle speed to slowly approach but not exceed the maximum limit, meet the speed limit requirements and ensure the stability of vehicle operation.

[0074] The acceleration-based vehicle speed limit control method disclosed in the present invention is described in detail below in conjunction with a specific embodiment. The acceleration-based vehicle speed limit control method specifically includes the following steps:

[0075] S1. Obtain the corresponding relationship between the vehicle acceleration and the intervention threshold speed when the vehicle is speed-limited through actual vehicle calibration.

[0076] Among them, in the embodiment of the present invention, the intervention threshold speed is the advance speed intervention amount. In step S1, a corresponding relationship table between vehicle acceleration and advance speed intervention amount is obtained through actual vehicle calibration; the intervention threshold speed is the actual vehicle speed corresponding to the speed limit intervention of the vehicle to eliminate the risk of vehicle speed overshoot, that is, to ensure that the vehicle speed does not exceed the speed limit, when the vehicle speed needs to be limited at a certain moment, the actual vehicle speed of the vehicle; Figure 3 As shown, the intervention threshold vehicle speed is associated with the current acceleration of the vehicle. The higher the acceleration, the lower the intervention threshold vehicle speed when the vehicle speed limit control is started.

[0077] S2. Determine the speed limit, configure the normal acceleration mode and the speed limit mode of the vehicle, and then monitor the current acceleration and speed values ​​of the vehicle in real time.

[0078] Specifically, in the embodiment of the present invention, step S2 is used to determine the speed limit of the current vehicle, and configure two modes of normal acceleration and speed limit for the vehicle to accelerate, and monitor the acceleration value and speed value of the vehicle in real time during the vehicle driving process; wherein, in this embodiment, the speed limit is obtained through the vehicle driving chart, and during the vehicle acceleration process, the vehicle acceleration mode is divided into a normal acceleration mode and a speed limit mode, wherein as Figure 4 As shown, when the vehicle is in the normal acceleration mode, the vehicle responds to the output control of the accelerator pedal and outputs torque according to the transmission input torque setting corresponding to the accelerator pedal, while in the speed limit mode, the transmission input torque no longer responds to the accelerator pedal signal and is input according to the torque value corresponding to the closed-loop control to achieve the target vehicle speed.

[0079] S3. Determine an intervention threshold vehicle speed corresponding to the current acceleration value according to the corresponding relationship and the current acceleration value, and obtain a first vehicle speed difference between the vehicle speed limit and the intervention threshold vehicle speed.

[0080] Specifically, in an embodiment of the present invention, the intervention threshold speed is associated with the real-time acceleration value of the vehicle. The higher the acceleration, the lower the threshold speed for starting the speed limit control. The intervention threshold speed is obtained by querying the relationship table and calculating.

[0081] S4. Compare and analyze the first vehicle speed difference with the current vehicle speed value to determine the current driving mode of the vehicle.

[0082] Among them, the step S4 is used to compare the first vehicle speed difference with the current speed value of the vehicle in real time, and determine whether the vehicle enters the speed limit mode through the comparison and analysis results. If it is determined at a certain moment that the vehicle enters the speed limit mode, proceed to the next step. If the vehicle does not enter the speed limit mode, the vehicle keeps accelerating according to the normal acceleration mode.

[0083] Specifically, in a specific embodiment of the present invention, in step S4, the comparative analysis step includes: S401, obtaining the first vehicle speed difference and the current speed value of the vehicle; S402, performing a difference operation on the first vehicle speed difference and the current speed value of the vehicle to obtain a second vehicle speed difference, and setting a difference comparison threshold; S403, performing a comparative analysis on the second vehicle speed difference and the difference comparison threshold; S404, if the second vehicle speed difference is greater than the difference comparison threshold, the vehicle is in a normal acceleration state, determining that the vehicle enters a normal acceleration mode, and jumping back to step S2 to continue real-time monitoring of the current acceleration and speed value of the vehicle; if the second vehicle speed difference is less than the difference comparison threshold, determining that the vehicle enters a speed limit mode.

[0084] Among them, Figure 5 As shown, in step S4 disclosed in the embodiment of the present invention, the comparison and analysis of the first vehicle speed difference and the current speed value of the vehicle is specifically a difference operation, the first vehicle speed difference is subtracted from the current speed value to obtain the second vehicle speed difference, and the second vehicle speed difference is compared with the difference comparison threshold value to determine whether the vehicle enters the speed limit mode at this moment; in this embodiment, the difference comparison threshold value is 0, and the magnitude relationship between the second vehicle speed difference and 0 is compared in real time. If it is greater than 0, the acceleration and speed of the vehicle continue to be monitored, and if it is less than or equal to zero, it is determined that the vehicle enters the speed limit mode at this time, that is, before the actual vehicle speed under acceleration conditions gradually approaches the speed limit, it is controlled according to the normal acceleration mode. At this time, the vehicle responds to the accelerator pedal torque, and the vehicle speed increases with the increase of the throttle opening. Subsequently, through real-time comparison and analysis, it is determined that when the vehicle speed reaches the intervention threshold speed, the vehicle enters the speed limit mode.

[0085] S5. If it is determined that the vehicle currently enters the speed limit mode, then a first-order low-pass filter is used to obtain an acceleration target curve that slowly approaches the speed limit from the current intervention threshold speed.

[0086] Among them, Figure 6 As shown, in an embodiment of the present invention, when it is determined that the vehicle enters the speed limit mode, in order to eliminate the risk of vehicle speed overshoot, the actual vehicle speed needs to be limited starting from the intervention threshold speed, and in order to ensure the smooth operation of the vehicle in the speed limit mode, in step S5, a vehicle acceleration target curve is defined to achieve the effect of the vehicle speed slowly approaching the speed limit from the intervention threshold speed.

[0087] Specifically, in a specific embodiment of the present invention, the step S5 includes: S501, if it is determined that the vehicle currently enters the speed limit mode; S501, then obtain the first-order filter characteristic equation: Y n =(1-A)X n +A*Y n-1 , where Y n For the control object, X n is the control object limit, Y n-1 is the control object in the previous state, and A is the filter coefficient; S502, then determine the filter coefficient A according to the current acceleration value of the vehicle; S503, finally set the acceleration target curve based on the speed limit and the vehicle speed value, and obtain the acceleration target curve equation: V n =(1-A)V tc +A*V n-1 , where V n is the target vehicle speed, V tc is the speed limit, V n-1 is the target vehicle speed at the previous moment.

[0088] Specifically, in this embodiment, in combination with the vehicle speed limit, a first-order low-pass filtering method is used to define an acceleration target curve that slowly approaches the speed limit; and, in the acceleration target curve equation, the filter coefficient A is a function of acceleration. The greater the acceleration value of the vehicle when entering the speed limit mode, the greater the filter coefficient, and the smoother the corresponding acceleration target curve rises.

[0089] S6. Based on the target vehicle speed in the acceleration target curve, the current actual vehicle speed is controlled to follow the target vehicle speed, and the actual vehicle speed slowly approaches the speed limit.

[0090] Among them, in this embodiment, step S6 is used to smoothly control the actual vehicle speed in the speed limit mode, by obtaining the target speed corresponding to each moment in the acceleration target curve and adjusting the vehicle transmission input control torque, so as to achieve the tracking control of the actual vehicle speed to the target speed, so that the actual vehicle speed steadily and slowly approaches the speed limit.

[0091] Specifically, in a specific embodiment of the present invention, the step S6 includes: S601, based on the acceleration target curve, obtaining the target speed corresponding to the vehicle in the speed limit mode; S602, adjusting the vehicle transmission input control torque through feedforward and PI control, limiting the actual vehicle speed, and performing the target speed tracking control on the actual vehicle speed; S603, real-time monitoring of the actual vehicle speed; S604, obtaining a third speed difference between the actual vehicle speed and the corresponding target speed, performing deviation control on the third speed difference, so that the actual vehicle speed slowly approaches the speed limit.

[0092] Specifically, in step S6, the actual vehicle speed is limited by controlling the torque value; in the embodiment of the present invention, feedforward plus PI control is used to adjust the vehicle transmission input control torque, and in order to prevent the vehicle actual speed from overshooting due to the large difference between the actual speed and the target speed during the process of following the target speed, the speed deviation is accurately controlled to achieve the following of the actual vehicle speed and the target speed.

[0093] Specifically, in a specific embodiment of the present invention, step S602 includes: S602.1, based on air resistance, tire rolling resistance and ramp resistance, obtaining the vehicle running resistance and; S602.2, combining vehicle parameter information and the vehicle running resistance and, calculating the transmission input torque:

[0094] T' tq =∑F*r / (i g ×i0×η)=(F f +F w +F i )*r / (i g ×i0×η)

[0095] =(mg*f+C d *A*V 2 / 21.15+mg*sinα)*r / (i g ×i0×η)

[0096] Among them, F f is the tire rolling resistance, F w is air resistance, F i is the slope resistance, m is the vehicle weight, g is the acceleration of gravity, f is the rolling resistance coefficient, C d is the air resistance coefficient, A is the frontal area of ​​the vehicle, α is the slope inclination, i g is the transmission ratio, i0 is the main reduction ratio, η is the transmission efficiency, and r is the tire radius;

[0097] S602.3, set the proportional coefficient K p And the integration coefficient Ki , combined with the third vehicle speed difference e(t), the proportional part and the integral part of the wheel end driving force U(t) are obtained respectively through PI control:

[0098] Proportional part U(t) = K p e(t),

[0099] Integration part

[0100] S602.4. Obtain torque correction value ΔT according to the wheel end driving force U(t) tq :

[0101]

[0102] S602.5. Calculate the transmission input control torque by combining the transmission input torque and the torque correction value:

[0103]

[0104] Wherein, in step S6, the real-time adjustment of the transmission input control torque is realized by feedforward + PI control. In the feedforward + PI control mode, the vehicle no longer responds to the accelerator pedal torque value, and the transmission end input torque no longer changes with the throttle opening, but operates according to the specific torque in the speed limit mode to achieve closed-loop control of the target vehicle speed; wherein the transmission input control torque is composed of the transmission input torque and the torque correction value; in the embodiment of the present invention, the transmission input torque is calculated based on wind resistance, tire rolling resistance, and slope resistance, and then according to the set K p , K i value, the difference between the actual vehicle speed and the target vehicle speed, the output torque correction value based on PI control, and finally the transmission input end control torque value is formed by the sum of the transmission input torque and the torque correction value.

[0105] Specifically, in a specific embodiment of the present invention, the S604 includes: S604.1, real-time monitoring of the third vehicle speed difference; S604.2, setting a first deviation range value, a second deviation range value and a third deviation range value; S604.3, when the actual vehicle speed approaches the target speed, performing regional control on the transmission input control torque according to the deviation range value.

[0106] Specifically, in a specific embodiment of the present invention, in step S604.3, the sub-region control is specifically: when the actual vehicle speed is within the first deviation range value of the target speed, integral holding is implemented, and the integral term in the transmission input control torque expression is The output results are no longer accumulated;

[0107] When the actual vehicle speed is within the second deviation range of the target speed, the integral part is cleared and the transmission input control torque is adjusted:

[0108] T tq =(mg*f+C d *A*V 2 / 21.15+mg*sinα+K p ·e(t))*r / (i g ×i0×η);

[0109] When the actual vehicle speed is within the third deviation range of the target speed, the feedforward, proportional part and integral part are cleared, and the transmission input control torque is adjusted: T tq =0; when the actual vehicle speed is within other deviation range values ​​of the target speed, the transmission input control torque is adjusted according to the normal state.

[0110] Among them, Figure 6 As shown, in this embodiment, step S604 is used to perform regional deviation control on the actual vehicle speed and its corresponding target speed in the speed limit mode, so as to prevent speed overshoot caused by the large difference between the actual vehicle speed and the target vehicle speed during the target curve following process, realize the speed curve following, eliminate the risk of speed overshoot, and further ensure the stability of vehicle operation.

[0111] Specifically, in a specific embodiment of the present invention, the first deviation range value is specifically ±1km / h, the second deviation range value is specifically greater than 1km / h and less than 3km / h, and the third deviation range value is specifically greater than 3km / h.

[0112] The present invention also provides a vehicle speed limit control system based on acceleration, comprising: an intervention threshold vehicle speed determination module, used to determine the corresponding relationship between the vehicle acceleration and the intervention threshold vehicle speed when the vehicle is speed-limited based on the vehicle acceleration table through the actual vehicle calibration data; a vehicle speed limit acquisition module, used to determine the vehicle speed limit according to the current state of the vehicle and the chart data; a vehicle speed monitoring module, used to monitor the current acceleration and speed value of the vehicle in real time; a vehicle speed difference calculation module, used to determine the intervention threshold vehicle speed corresponding to the current acceleration value according to the current acceleration value of the vehicle, and obtain the first vehicle speed difference between the speed limit value and the intervention threshold vehicle speed; a driving mode configuration module, used to In configuring a normal acceleration mode or a speed limit mode for the vehicle, the first speed difference is compared and analyzed with the current speed value of the vehicle to determine the current driving mode of the vehicle; a speed target curve calculation module obtains an acceleration target curve that slowly approaches the speed limit from the current intervention threshold speed through a first-order low-pass filter; a speed following control module is used to adjust the vehicle transmission input control torque according to the target speed in the acceleration target curve, and perform tracking control on the target speed of the current actual vehicle speed; a speed deviation control module is used to perform deviation control on the actual vehicle speed and its corresponding target speed, which also has the above-mentioned technical effects.

[0113] In addition, the present invention also provides a vehicle, which includes the acceleration-based speed limit control system and also has the above-mentioned technical effects.

[0114] In summary, the acceleration-based vehicle speed limit control method, control system, and vehicle involved in the embodiments of the present invention can solve the problem of unstable operation of the vehicle when the vehicle speed is limited. For the acceleration-based speed limit control method disclosed in the present invention, the method flow mainly includes six steps: first, the actual vehicle needs to be calibrated to obtain a corresponding relationship table between the vehicle acceleration and the intervention threshold speed when the vehicle is speed limited. The intervention threshold speed is the actual vehicle speed corresponding to the speed limit intervention of the vehicle in order to eliminate the risk of vehicle speed overshoot. The intervention threshold speed is associated with the current acceleration of the vehicle. The higher the acceleration, the lower the intervention threshold speed when the speed limit control is started; then, the speed limit value of the vehicle when driving is obtained through vehicle chart data, and the normal acceleration mode and the speed limit mode are configured for the vehicle during the driving process, and the vehicle acceleration and speed value are monitored in real time. In the normal acceleration mode, the vehicle responds to the accelerator pedal output control and outputs torque according to the transmission input torque setting corresponding to the accelerator pedal. In the speed limit mode, the transmission input torque no longer responds to the accelerator pedal signal, and is input according to the torque value corresponding to the closed-loop control of the target speed; then, the corresponding acceleration value is determined according to the acceleration value obtained in real time. The intervention threshold speed is determined, and the intervention threshold speed is calculated as a difference between the intervention threshold speed and the speed limit to obtain the first speed difference; then the current speed value of the vehicle is compared with the first speed difference in real time to determine whether the vehicle has entered the speed limit mode. If it is determined that the vehicle has entered the speed limit mode, the next step is performed, otherwise the vehicle accelerates according to the normal acceleration mode, and the vehicle acceleration and speed value are continuously monitored in real time; when it is determined that the vehicle has entered the speed limit mode, a first-order low-pass filtering method is immediately used to define an acceleration target curve that slowly approaches the speed limit from the intervention threshold speed, and the filter coefficient in the acceleration target curve is a function of acceleration. When entering the speed limit mode, the greater the acceleration of the vehicle, the greater the filter coefficient, and the more gently the corresponding acceleration target curve rises; finally, in the speed limit mode, based on the target speed in the acceleration target curve, the vehicle adopts feedforward plus PI control to achieve the following of the actual vehicle speed and the target speed, so that the actual vehicle speed slowly approaches the speed limit, thereby ensuring the stability of the vehicle. It can be seen that, compared with the prior art, the technical solution involved in the present invention can control the vehicle speed to slowly approach but not exceed the maximum limit, thereby meeting the speed limit requirements while ensuring the stability of the vehicle operation.

[0115] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A vehicle speed limit control method based on acceleration, characterized in that: The following steps are involved: S1. Obtain the corresponding relationship between the vehicle acceleration and the intervention threshold speed when the vehicle is speed-limited through real vehicle calibration; S2. Determine the speed limit, configure the normal acceleration mode and speed limit mode of the vehicle, and monitor the current acceleration and speed value of the vehicle in real time; S3. determining an intervention threshold vehicle speed corresponding to the current acceleration value according to the corresponding relationship and the current acceleration value, and obtaining a first vehicle speed difference between the vehicle speed limit and the intervention threshold vehicle speed; S4, comparing and analyzing the first vehicle speed difference with the current vehicle speed value to determine the current driving mode of the vehicle; S5. If the vehicle currently enters the speed limit mode, an acceleration target curve is obtained by first-order low-pass filtering from the current intervention threshold speed slowly approaching the speed limit; S6. Based on the target vehicle speed in the acceleration target curve, the current actual vehicle speed is controlled to follow the target vehicle speed, so that the actual vehicle speed slowly approaches the speed limit.

2. The acceleration-based vehicle speed limit control method according to claim 1, characterized in that: In step S4, the comparative analysis step includes: S401, obtaining the first vehicle speed difference and the current vehicle speed value; S402, performing a difference operation on the first vehicle speed difference and the current vehicle speed value to obtain a second vehicle speed difference, and setting a difference comparison threshold; S403, comparing and analyzing the second vehicle speed difference with the difference comparison threshold; S404: If the second vehicle speed difference is greater than the difference comparison threshold, the vehicle is in a normal acceleration state, and the vehicle is determined to enter a normal acceleration mode, and the process returns to step S2 to continue to monitor the current acceleration and speed of the vehicle in real time; If the second vehicle speed difference is less than the difference comparison threshold, it is determined that the vehicle enters a speed limit mode.

3. The acceleration-based vehicle speed limit control method according to claim 2, characterized in that: The step S5 comprises: S501, determining that the vehicle is in the speed limit mode; S501, obtain the first-order filter characteristic equation: Y n =(1-A)X n +A*Y n-1 , where Y n For the control object, X n is the control object limit, Y n-1 is the control object in the previous state, A is the filter coefficient; S502, determining a filter coefficient A according to the current acceleration value of the vehicle; S503: Based on the vehicle speed limit and the vehicle speed value, set an acceleration target curve and obtain an acceleration target curve equation: V n =(1-A)V tc +A*V n-1 , where V n is the target vehicle speed, V tc is the speed limit, V n-1 is the target vehicle speed at the previous moment.

4. The acceleration-based vehicle speed limit control method according to claim 1, characterized in that: The step S6 comprises: S601, based on the acceleration target curve, obtaining a target vehicle speed corresponding to the vehicle in a speed limit mode; S602, adjusting the vehicle transmission input control torque through feedforward and PI control, limiting the actual vehicle speed, and performing a tracking control on the actual vehicle speed to the target speed; S603, monitoring the actual speed of the vehicle in real time; S604: Obtain a third vehicle speed difference between the actual vehicle speed and the corresponding target vehicle speed, and perform deviation control on the third vehicle speed difference so that the actual vehicle speed slowly approaches the vehicle speed limit.

5. The acceleration-based vehicle speed limit control method according to claim 4, characterized in that: Step S602 includes: S602.

1. Obtain the vehicle running resistance and based on air resistance, tire rolling resistance and ramp resistance; S602.

2. Calculate the transmission input torque by combining the vehicle parameter information and the vehicle running resistance: T' tq =∑F*r / (i g ×i0×η)=(F f +F w +F i )*r / (i g ×i0×η) =(mg*f+C d *A*V 2 / 21.15+mg*sinα)*r / (i g ×i0×η) Among them, F f is the tire rolling resistance, F w is air resistance, F i is the slope resistance, m is the vehicle weight, g is the acceleration of gravity, f is the rolling resistance coefficient, C d is the air resistance coefficient, A is the frontal area of ​​the vehicle, α is the slope inclination, i g is the transmission ratio, i0 is the main reduction ratio, η is the transmission efficiency, and r is the tire radius; S602.3, set the proportional coefficient K p And the integration coefficient K i , combined with the third vehicle speed difference e(t), the proportional part and the integral part of the wheel end driving force U(t) are obtained respectively through PI control: Proportional part U(t) = K p e(t), S602.

4. Obtain torque correction value ΔT according to the wheel end driving force U(t) tq : S602.

5. Calculate the transmission input control torque by combining the transmission input torque and the torque correction value:

6. The acceleration-based vehicle speed limit control method according to claim 5, characterized in that: The S604 includes: S604.

1. Monitor the third vehicle speed difference in real time; S604.

2. Set a first deviation range value, a second deviation range value, and a third deviation range value; S604.

3. When the actual vehicle speed approaches the target vehicle speed, the transmission input control torque is controlled in different regions according to the deviation range value.

7. The acceleration-based vehicle speed limit control method according to claim 6, characterized in that: In step S604.3, the sub-region control is specifically as follows: When the actual speed of the vehicle is within the first deviation range of the target speed, integral holding is implemented, and the integral term in the transmission input control torque expression The output results are no longer accumulated; When the actual vehicle speed is within the second deviation range of the target speed, the integral part is cleared and the transmission input control torque is adjusted: T tq =(mg*f+C d *A*V 2 / 21.15+mg*sinα+K p ·e(t))*r / (i g ×i0×η); When the actual vehicle speed is within the third deviation range of the target speed, the feedforward, proportional part and integral part are cleared, and the transmission input control torque is adjusted: T tq =0; When the actual vehicle speed is within other deviation ranges of the target vehicle speed, the transmission input control torque is adjusted in a normal state.

8. The acceleration-based vehicle speed limit control method according to claim 7, characterized in that: The first deviation range value is specifically ±1 km / h, the second deviation range value is specifically greater than 1 km / h and less than 3 km / h, and the third deviation range value is specifically greater than 3 km / h.

9. A vehicle speed limit control system based on acceleration, characterized in that: include: An intervention threshold speed determination module is used to determine the corresponding relationship between the vehicle acceleration and the intervention threshold speed when the vehicle speed is limited based on the vehicle accelerometer through real vehicle calibration data; A speed limit acquisition module is used to determine the speed limit according to the current state of the vehicle and chart data; Vehicle speed monitoring module, used to monitor the vehicle's current acceleration and speed in real time; A vehicle speed difference calculation module, used to determine an intervention threshold vehicle speed corresponding to the current acceleration value according to the vehicle's current acceleration value, and obtain a first vehicle speed difference between the vehicle speed limit and the intervention threshold vehicle speed; A driving mode configuration module, configured to configure a normal acceleration mode or a speed limit mode for the vehicle, compare and analyze the first vehicle speed difference with the current speed value of the vehicle, and determine the current driving mode of the vehicle; A vehicle speed target curve calculation module, which obtains an acceleration target curve that slowly approaches the vehicle speed limit from the current intervention threshold vehicle speed through a first-order low-pass filter; A vehicle speed following control module, used to adjust the vehicle transmission input control torque according to the target vehicle speed in the acceleration target curve, and perform following control on the target vehicle speed for the current actual vehicle speed; The vehicle speed deviation control module is used to perform deviation control on the actual vehicle speed and its corresponding target vehicle speed.

10. A vehicle, characterized in that: The vehicle includes the acceleration-based vehicle speed limit control system of claim 9.

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