CN112455436A - Vehicle deceleration control method and vehicle control unit - Google Patents

Vehicle deceleration control method and vehicle control unit Download PDF

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Publication number
CN112455436A
CN112455436A CN202011367385.7A CN202011367385A CN112455436A CN 112455436 A CN112455436 A CN 112455436A CN 202011367385 A CN202011367385 A CN 202011367385A CN 112455436 A CN112455436 A CN 112455436A
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vehicle
speed
deceleration
distance
driver
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李垚
刘强
李祥杰
孔令伟
曾路遥
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United Automotive Electronic Systems Co Ltd
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United Automotive Electronic Systems Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units, or advanced driver assistance systems for ensuring comfort, stability and safety or drive control systems for propelling or retarding the vehicle
    • B60W30/08—Active safety systems predicting or avoiding probable or impending collision or attempting to minimise its consequences
    • B60W30/09—Taking automatic action to avoid collision, e.g. braking and steering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L7/00—Electrodynamic brake systems for vehicles in general
    • B60L7/10—Dynamic electric regenerative braking
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2520/00—Input parameters relating to overall vehicle dynamics
    • B60W2520/10—Longitudinal speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2554/00—Input parameters relating to objects
    • B60W2554/40—Dynamic objects, e.g. animals, windblown objects
    • B60W2554/404—Characteristics
    • B60W2554/4042—Longitudinal speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2554/00—Input parameters relating to objects
    • B60W2554/80—Spatial relation or speed relative to objects
    • B60W2554/802—Longitudinal distance
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/80—Technologies aiming to reduce greenhouse gasses emissions common to all road transportation technologies
    • Y02T10/84—Data processing systems or methods, management, administration

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Automation & Control Theory (AREA)
  • Power Engineering (AREA)
  • Control Of Driving Devices And Active Controlling Of Vehicle (AREA)

Abstract

The invention provides a vehicle deceleration control method and a vehicle control unit, wherein the vehicle deceleration control method judges whether a driver of a vehicle has an intention of deceleration according to the vehicle speed of the vehicle, the vehicle speed of a front vehicle and the relative distance between the vehicle and the front vehicle at the corresponding time; when a deceleration intention exists, whether the vehicle needs to be decelerated and driven is judged by calculating a braking distance required to be driven when the vehicle speed is braked to reach the vehicle speed of the front vehicle after the throttle of the vehicle is released, a first deceleration distance required to be driven when the vehicle speed is completely slid to reach the vehicle speed of the front vehicle and a second deceleration distance required to be driven when the vehicle speed is completely braked to reach the vehicle speed of the front vehicle, and a deceleration mode adopted when the vehicle needs to be decelerated and driven is determined; and the vehicle in different deceleration stages is subjected to deceleration control according to the determined deceleration mode and the mode of taking over control by the driver, so that the vehicle can perform sliding and motor braking recovery actions, and better fuel economy and driving safety are realized.

Description

Vehicle deceleration control method and vehicle control unit
Technical Field
The invention relates to the technical field of automobiles, in particular to a vehicle deceleration control method and a vehicle control unit.
Background
Deceleration is an unavoidable behavior of the driver during driving. Different from the determination scenes of red lights, crossroads, speed limit signs and the like in the front, the condition of deceleration or parking of the front vehicle has great uncertainty and dynamics, and a driver often cannot quickly determine whether the vehicle needs to decelerate, so that the final deceleration is too violent, a brake system is damaged, the driving feeling is influenced, and the kinetic energy of the vehicle cannot be recovered to the maximum extent.
Please refer to fig. 1, which shows a relationship curve between a vehicle speed and a driving distance during deceleration of a driver after a front vehicle decelerates in a conventional case. As shown in fig. 1, since the driver in the first half considers that deceleration is not necessary, the first half keeps running at a constant vehicle speed, and braking action is taken when the driver approaches the front and finds that deceleration is necessary. For the deceleration process adopted by the driver, the deceleration process cannot be controlled and realized based on the existing traditional vehicle control system. The conventional vehicle deceleration is usually carried out by the judgment of a driver, however, once the driver cannot accurately judge the deceleration time, the braking action is too early or too late. If the brake is too early, the driver needs to accelerate again on the backward stroke; if the brake is applied too late, safety problems and an uncomfortable driving feeling are brought about. Meanwhile, unnecessary acceleration behavior before deceleration and heat loss of the friction disc caused by braking of a driver bring about increase of the overall fuel consumption of the vehicle.
In view of the problems of the prior art in the vehicle deceleration process, those skilled in the art are always seeking solutions.
Disclosure of Invention
The invention aims to provide a vehicle deceleration control method and a vehicle controller, which are used for solving the problems existing in the vehicle deceleration process in the prior art.
In order to solve the above technical problem, the present invention provides a vehicle deceleration control method, including:
acquiring the speed of the vehicle, the speed of the vehicle in front and the relative distance between the vehicle and the vehicle in front in real time;
judging whether the driver of the vehicle has a deceleration intention or not according to the vehicle speed of the vehicle at the current moment, the vehicle speed of the vehicle in front and the relative distance between the vehicle and the vehicle in front at each moment;
when the judgment result shows that the driver of the vehicle has the deceleration intention, respectively calculating the first time (t) required for the vehicle to completely slide to reach the vehicle speed of the front vehicle at the vehicle speed after the throttle of the vehicle is releasedc) And a first deceleration distance(s) traveledc) And a second time (t) required for full motor braking at the speed of the vehicle to reach the speed of the vehicle aheadr) And a second deceleration distance(s) traveledr)；
Calculating the braking distance(s) required to be traveled when the speed of the vehicle is braked to reach the speed of the vehicle in front after the throttle of the vehicle is releasedsum)；
According to the braking distance, the first deceleration distance(s)c) And the second deceleration distance(s)r) Judging whether the vehicle needs to be decelerated and driven, and determining a deceleration mode adopted when the vehicle needs to be decelerated and driven;
prompting the driver of the vehicle to release the accelerator after judging that the vehicle needs to run at a reduced speed;
and after the accelerator is released by the driver of the vehicle, performing vehicle deceleration control according to the deceleration mode until the vehicle speed is decelerated to reach a vehicle speed threshold value and/or the relative distance between the driver of the vehicle and the front vehicle reaches a distance threshold value, and prompting the driver of the vehicle to take over the vehicle deceleration control.
Optionally, in the vehicle deceleration control method, the speed of the vehicle ahead and the relative distance between the vehicle and the vehicle ahead are obtained based on radar monitoring configured for the vehicle.
Optionally, in the vehicle deceleration control method, for each time, the process of determining whether the driver of the vehicle has the deceleration intention according to the vehicle speed of the vehicle at the current time, the vehicle speed of the vehicle ahead, and the relative distance between the vehicle and the vehicle ahead is as follows:
judging whether the relative speed of the vehicle and the front vehicle at the current moment is smaller than a relative speed threshold value and whether the relative distance is smaller than a relative distance threshold value; if the relative speed is smaller than the relative speed threshold value and the relative distance is smaller than the relative distance threshold value, the driver of the vehicle has a deceleration intention; otherwise, the driver of the vehicle has no intention of deceleration.
Optionally, in the vehicle deceleration control method, the first deceleration distance(s) is calculatedc) The second deceleration distance(s)r) The first time (t)c) And said second time (t)r) The following formula is adopted:
Figure BDA0002804697290000021
in the formula (1), FrIs the vehicle sliding resistance related to the vehicle speed v; mdragIs equal to the engine speed neThe associated engine drag torque; mgenIs equal to the motor speed nmThe associated motor braking torque; η is the efficiency of the relevant component; i.e. ioThe engine main reduction ratio; i.e. igIs the engine gear ratio; m is the vehicle mass; delta is a vehicle rotation conversion coefficient;
Figure BDA0002804697290000031
when the engine speed and the motor speed are in a fixed gear, the engine speed and the motor speed are in a proportional relation with the vehicle speed, so that the formula (1) is converted into the following formula:
Figure BDA0002804697290000032
Figure BDA0002804697290000033
Figure BDA0002804697290000034
in the formulae (3) and (4), scA first deceleration distance; srA second deceleration distance; v. of0The speed of the vehicle is the speed of the vehicle when the accelerator is loosened; v is the speed of the vehicle; v. oftIs the forward vehicle speed.
Optionally, in the vehicle deceleration control method, a formula for calculating a braking distance required to be traveled when the vehicle speed brake of the vehicle reaches the vehicle speed of the vehicle ahead after the vehicle releases the throttle is as follows:
ssum＝s0+sm (5)；
in the formula (5), ssumIs the braking distance; s0The relative distance between the vehicle and the front vehicle when the vehicle releases the throttle; smThe distance traveled by the preceding vehicle at the first time or the distance traveled by the preceding vehicle at the second time.
Optionally, in the vehicle deceleration control method, the braking distance(s) is set according to the braking distancesum) The first deceleration distance(s)c) And the second deceleration distance(s)r) The basis for judging whether the vehicle needs to run at a reduced speed is as follows:
determining the braking distance(s)sum) Whether or not it is less than the first deceleration distance(s)c) If yes, the vehicle needs to run at a reduced speed; on the contrary, the vehicle does not need to run at a reduced speed.
Optionally, in the vehicle deceleration control method, the basis for determining the deceleration mode to be used when the vehicle is running with deceleration is as follows:
Figure BDA0002804697290000035
the CR mode is a control mode of firstly sliding and then braking and decelerating the motor; the FR mode is a complete motor braking deceleration control mode; ssumIs the braking distance; scA first deceleration distance; srIs the second deceleration distance.
Optionally, in the vehicle deceleration control method, in the process of performing vehicle deceleration control in the FR mode, the vehicle controller performs motor torque adjustment according to a difference between a relative distance between the vehicle and the front vehicle actually acquired at each moment after the vehicle is released from the throttle and a theoretical relative distance between the vehicle and the front vehicle at the corresponding moment;
wherein the theoretical relative distance calculation formula is as follows:
slact＝sr-snow＝sr-(∫vfr(v,ig)dv+C(s0,vt))；
wherein s islactTheoretical relative distance; srA second deceleration distance; snowThe running distance of the vehicle; s0The relative distance between the vehicle and the front vehicle when the vehicle releases the throttle; v. oftThe speed of the vehicle ahead of the moment when the throttle of the vehicle is released; c is a group s0And vtA determined constant term; i.e. igIs the engine gear ratio.
Optionally, in the vehicle deceleration control method, a driver of the vehicle is prompted to release the accelerator based on a double-pulse vibration mode of an active feedback pedal (APM) as a reminding mode.
Optionally, in the vehicle deceleration control method, a driver of the vehicle is prompted to take over the vehicle deceleration control based on an automobile instrument human-machine interface (HMI).
Optionally, in the vehicle deceleration control method, the vehicle speed threshold is related to a vehicle speed of a front vehicle and an idle speed of a self vehicle; the distance threshold is related to the speed of the vehicle, the gear of the vehicle and the speed of the vehicle in front.
Correspondingly, the invention also provides a vehicle control unit, which comprises: a processor and a memory, the memory having stored therein a computer program; the processor executes the computer program stored in the memory to cause the vehicle control unit to execute the vehicle deceleration control method.
In the vehicle deceleration control method and the vehicle control unit provided by the invention, for each time, firstly, whether the driver of the vehicle has the deceleration intention or not is judged according to the vehicle speed of the vehicle, the vehicle speed in front and the relative distance between the vehicle and the vehicle in front at the corresponding time; secondly, when a deceleration intention exists, whether the vehicle needs to be decelerated and driven is judged by calculating a braking distance required to be driven when the vehicle speed is braked to reach the vehicle speed in front after the throttle of the vehicle is released, a first deceleration distance required to be driven when the vehicle speed is completely slid to reach the vehicle speed in front and a second deceleration distance required to be driven when the vehicle speed is completely braked to reach the vehicle speed in front through a motor, and a deceleration mode adopted when the vehicle needs to be decelerated and driven is determined; and finally, performing deceleration control on the vehicle at different deceleration stages according to the determined deceleration mode and the mode of taking over control by the driver, so that the vehicle can perform sliding and motor braking recovery actions, and better fuel economy and driving safety are realized.
Drawings
FIG. 1 is a graph showing the relationship between the speed and the distance traveled by a driver during deceleration of a preceding vehicle in a conventional case;
FIGS. 2a and 2b are flow charts of a vehicle deceleration control method according to an embodiment of the present invention;
FIG. 3 is a comparison graph of the relationship between the speed and the distance traveled by the driver during deceleration of the vehicle ahead before and after the deceleration control method of the vehicle according to the present invention is applied;
FIG. 4 is a schematic diagram of a vehicle deceleration control method of the present invention.
Detailed Description
The following describes the vehicle deceleration control method and the vehicle control unit in further detail with reference to the accompanying drawings and specific embodiments. Advantages and features of the present invention will become apparent from the following description and from the claims. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than the number, shape and size of the components in actual implementation, and the form, quantity and proportion of the components in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated.
Certain terms are used throughout the description and claims to refer to particular system components. As one skilled in the art will appreciate, different companies may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the description and claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to …".
As used in this application and the appended claims, the terms "a," "an," "the," and/or "the" are not intended to be inclusive in the singular, but rather are intended to be inclusive in the plural unless the context clearly dictates otherwise. In general, the terms "comprises" and "comprising" merely indicate that steps and elements are included which are explicitly identified, that the steps and elements do not form an exclusive list, and that a method or apparatus may include other steps or elements.
Furthermore, each of the embodiments described below has one or more technical features, and thus, the use of the technical features of any one embodiment does not necessarily mean that all of the technical features of any one embodiment are implemented at the same time or that only some or all of the technical features of different embodiments are implemented separately. In other words, those skilled in the art can selectively implement some or all of the features of any embodiment or combinations of some or all of the features of multiple embodiments according to the disclosure of the present invention and according to design specifications or implementation requirements, thereby increasing the flexibility in implementing the invention.
The present invention will be described in more detail with reference to the accompanying drawings, in order to make the objects and features of the present invention more comprehensible, embodiments thereof will be described in detail below, but the present invention may be implemented in various forms and should not be construed as being limited to the embodiments described.
Please refer to fig. 2a and fig. 2b, which are flowcharts of a vehicle deceleration control method according to the present invention. As shown in fig. 2a and 2b, the vehicle deceleration control method includes the steps of:
first, step S1 is executed to acquire the vehicle speed of the host vehicle, the vehicle speed of the vehicle ahead, and the relative distance between the host vehicle and the vehicle ahead in real time.
The speed of the vehicle can be obtained based on the sensor of the vehicle; the radar monitoring based on the vehicle configuration can acquire the speed of the front vehicle and the relative distance between the vehicle and the front vehicle, and the values of the speed of the front vehicle, the speed of the vehicle and the relative distance can be changed along with the running process of the vehicle.
Next, step S2 is executed to determine whether the driver of the host vehicle has an intention to decelerate based on the vehicle speed of the host vehicle at the present time, the vehicle speed of the vehicle ahead, and the relative distance between the host vehicle and the vehicle ahead.
The process of judging whether the driver of the vehicle has the deceleration intention or not according to the vehicle speed of the vehicle at the current moment, the vehicle speed of the vehicle in front and the relative distance between the vehicle and the vehicle in front at each moment is as follows:
judging whether the relative speed of the vehicle and the front vehicle at the current moment is smaller than a relative speed threshold value and whether the relative distance is smaller than a relative distance threshold value; if the relative speed is smaller than the relative speed threshold value and the relative distance is smaller than the relative distance threshold value, the driver of the vehicle has a deceleration intention; otherwise, the driver of the vehicle has no intention of deceleration.
Is formulated as follows:
when there is an intention to decelerate, satisfy
Figure BDA0002804697290000061
Where detV is a relative vehicle speed threshold, detV ═ f (v, s)act)，sactFor the vehicle at any time from the frontThe relative distance v is the speed of the vehicle; detD is a relative distance threshold detD, and the detD is 170m, because the detection distance of the millimeter wave radar can only reach that far.
Subsequently, step S3 is executed, and if it is determined that the driver of the host vehicle has an intention to decelerate, the first time t required for the host vehicle to completely coast to the vehicle speed of the vehicle ahead at the host vehicle speed after the throttle of the host vehicle is released is calculatedcAnd a first deceleration distance s traveledcAnd a second time t required for the motor to brake completely at the speed of the vehicle to reach the speed of the vehicle aheadrAnd a second deceleration distance s traveledr(ii) a Wherein the first deceleration distance s is calculatedcSecond deceleration distance srA first time tcAnd a second time trThe following formula is adopted:
Figure BDA0002804697290000071
in the formula (1), FrThe vehicle sliding resistance related to the vehicle speed v can be obtained through vehicle speed fitting; mdragIs equal to the engine speed neThe relevant engine drag torque can be obtained by engine speed fitting; mgenIs equal to the motor speed nmThe related motor braking torque can be obtained by fitting the external characteristics of the motor and the rotating speed of the motor; η is the efficiency of the relevant component; i.e. ioThe engine main reduction ratio; i.e. igIs the engine gear ratio; m is the vehicle mass; delta is a vehicle rotation conversion coefficient;
Figure BDA0002804697290000072
when the engine speed and the motor speed are in a fixed gear, the engine speed and the motor speed are in a proportional relation with the vehicle speed, so that the formula (1) is converted into the following formula:
Figure BDA0002804697290000073
Figure BDA0002804697290000074
Figure BDA0002804697290000075
in the formulas (3) and (4), v0The initial speed of the vehicle is the initial speed of the vehicle when the accelerator is loosened; v is the speed of the vehicle; v. oftIs the forward vehicle speed.
Different from the static target, the front vehicle has a dynamic behavior, and whether the vehicle needs to decelerate is determined, and the dynamic behavior of the front vehicle needs to be considered, for which specific reasons should be understood with reference to fig. 4.
As shown in fig. 4, if the relative distance between the host vehicle and the preceding vehicle at the initial time falls within srAnd scAnd the vehicle adopts the deceleration action of firstly sliding and then braking the motor, and the switching point of the theoretical sliding and the braking of the motor is shown in figure 4. However, when the vehicle travels to the position of the first preceding vehicle, the preceding vehicle travels a further distance smTherefore, it is necessary to consider the dynamic behavior of the preceding vehicle in determining whether the own vehicle needs to be decelerated.
Assuming that it takes time tc for the own vehicle to completely coast to the target vehicle speed (i.e., the vehicle speed of the preceding vehicle when the own vehicle travels to the initial preceding vehicle position) after the accelerator is released, the preceding vehicle travel distance during this time is set to
Figure BDA0002804697290000081
Wherein v istFor the vehicle speed of the preceding vehicle, α represents the acceleration of the preceding vehicle at the present time, assuming α is at time tcThe inner part is constant.
Next, step S4 is executed to calculate the braking distance required for the vehicle to travel when the vehicle speed brake reaches the vehicle speed ahead after the throttle of the vehicle is released.
Specifically, the braking distance is calculated by the following formula: ssum＝s0+sm (5)；
In the formula (5), ssumIs the braking distance; s0The relative distance between the vehicle and the front vehicle when the vehicle releases the throttle; smFor the preceding vehicle at a first time tcDistance traveled or preceding vehicle at second time trThe distance traveled.
Then, step S5 is executed to determine the braking distance and the first deceleration distance ScAnd the second deceleration distance srJudging whether the vehicle needs to be decelerated and driven, and determining a deceleration mode adopted when the vehicle needs to be decelerated and driven;
for better understanding of S4 and S5, please refer to fig. 4, if case 1: s0+sm>scThat is, the vehicle cannot collide with the vehicle ahead even though coasting, if a deceleration strategy is triggered at this time, it means that the vehicle decelerates too early, and the driver may be required to accelerate later, so the deceleration strategy at this time should be waiting for case 2: s0+sm<scIs triggered, thus determining the braking distance ssum＝s0+smWhether or not it is less than the first deceleration distance sc(i.e., judgment ssum<scIs there a ) Becomes the judgment basis for judging whether the vehicle needs to be decelerated and driven, if the judgment result is ssum<scIf so, the vehicle needs to run at a reduced speed; on the contrary, the vehicle does not need to run at a reduced speed.
In order to improve the fuel economy and driving safety performance of the vehicle, the region case2 of the deceleration control strategy is further divided into two sub-regions (i.e. s)r<s0+sm<scAnd s0+sm<sr) And correspondingly allocating a deceleration control strategy for each sub-area, wherein the specific allocation condition is as follows:
Figure BDA0002804697290000082
the CR mode is a control mode of firstly sliding and then braking and decelerating the motor; the FR mode is a complete motor braking deceleration control mode; ssum is the braking distance; sc is a first deceleration distance; sr is the second deceleration distance.
In the case of a dynamic environment, when the vehicle deceleration control strategy is involved, there is no full freewheel deceleration control mode (abbreviated as FC mode), mainly for the following reasons: for example, taking a front vehicle in a dynamic environment as an example of a tracking target, after the front vehicle is in a dynamic state, the front vehicle is in a dynamic state and then tracks the front vehicle as a follow-up target, so that the vehicle speed of the front vehicle is the target vehicle speed of the vehicle, and the relative distance between the two vehicles and the vehicle speed cannot be adjusted by using motor braking through full freewheeling, so that the full freewheeling deceleration control mode in the vehicle deceleration control strategy for the dynamic environment has no significance for vehicle deceleration control adjustment, and only includes a CR mode (first coasting and then motor braking deceleration control mode) and an FR mode (full motor braking deceleration control mode).
Next, step S6 is executed to prompt the driver of the host vehicle to release the accelerator when it is determined that the host vehicle needs to run at a reduced speed.
In the embodiment, the driver of the vehicle is prompted to release the accelerator mainly based on an active feedback pedal (APM). The active feedback pedal has multiple modes, including single-pulse vibration, double-pulse vibration, variable pressure pedal and other modes. When a driver feels that the APM regularly vibrates to remind, the accelerator is loosened; if the driver does not release the accelerator all the time, the APM stops vibrating after vibrating for a period of time.
Next, step S7 is executed to prompt the driver of the vehicle to take over the vehicle deceleration control until the vehicle speed of the vehicle decelerates to reach a vehicle speed threshold and/or the relative distance between the vehicle and the vehicle ahead reaches a distance threshold, according to the deceleration pattern, after the driver of the vehicle releases the throttle. Specifically, the vehicle speed threshold value is related to the vehicle speed of a front vehicle and the idle speed of a self vehicle; the distance threshold is related to the speed of the vehicle, the gear of the vehicle and the speed of the vehicle in front. Preferably, the driver of the vehicle is prompted to take over the vehicle deceleration control based on an automobile instrument Human Machine Interface (HMI).
S7 will be described in detail below by taking the FR mode and the CR mode as examples of the deceleration mode, and refer to fig. 2b specifically.
As shown in fig. 2b, if the deceleration mode is the FR mode, the vehicle directly enters the motor braking energy recovery state after the driver releases the throttle. The vehicle control unit can control the vehicle according to the relative distance s between the throttle releasing moment of the vehicle and the vehicle in front0And the vehicle speed v ahead of the moment when the vehicle releases the throttletIn order to calculate the ideal driving track of the vehicle, the calculation method comprises the following steps:
the running distance s of the vehicle can be calculated according to the formula (1)now＝∫vfr(v,ig)dv+C(s0,vt) (ii) a Then(s)r-snow) The vehicle controller actually obtains the relative distance s between the vehicle and the front vehicle at each moment after the throttle of the vehicle is released according to the theoretical relative distance s between the vehicle and the front vehicle after the throttle of the vehicle is releasedactTheoretical relative distance s between the host vehicle and the preceding vehicle at the corresponding timelactDifference (i.e. s) ofact-slact) And adjusting the motor torque to enable the actual running track of the vehicle to be close to the ideal running track by utilizing the dynamic adjustment of the motor torque, thereby realizing safe energy-saving speed reduction.
The theoretical relative distance calculation formula is as follows:
slact＝sr-snow＝sr-(∫vfr(v,ig)dv+C(s0,vt))；
wherein s islactTheoretical relative distance; srA second deceleration distance; snowThe running distance of the vehicle; s0Is the relative distance s between the vehicle and the front vehicle when the vehicle releases the throttle0The value of (a) is time-varying; v. oftThe speed v of the vehicle ahead of the moment when the throttle of the vehicle is releasedtThe value of (a) is time-varying; c is a group s0And vtA determined constant term; i.e. igIs the engine gear ratio.
Therefore, in the FR mode, the motor brake cannot be fully relied on to reach the deceleration point, and the driver is also required to step on the one-foot brake, that is, the subsequent driver takes over the operation of deceleration control. The FR mode has the significance that most of kinetic energy in the first half can be recycled, and the speed of the vehicle is rapidly reduced, so that energy is saved, and safety is guaranteed.
As shown in FIG. 2b, if the deceleration mode is CR mode, the vehicle enters a natural coasting state after the driver releases the throttle, and the vehicle controller calculates an expected traveling distance s from the current vehicle speed to the vehicle speed expected to reach the front vehicle when the vehicle is braked by the motorr_prdcIf s isr_prdc>0, it means that the vehicle does not reach the switching point of natural coasting and motor braking (corresponding to the actual CR switching point in fig. 4); if sr_prdc<And 0, the vehicle crosses the switching point of the natural sliding and the motor braking (corresponding to the actual CR switching point in the figure 4), and the free sliding state is switched to the motor braking state. The vehicle travel track then follows the long dashed black line, and it should be noted that this dashed black line track is not deterministic, but follows the movement of the preceding vehicle.
As can be seen from fig. 3 and 4, in the prior art, the deceleration timing of the vehicle needs to be determined by the human operator, and the vehicle should be switched from the natural coasting to the motor braking at the theoretical CR switching point (i.e., the switching node for switching the natural coasting to the motor braking), whereas the vehicle actually switches from the natural coasting to the motor braking at the actual CR switching point due to the determination error. After the vehicle deceleration control method is adopted, a driver can accurately judge the deceleration time (namely the theoretical CR switching point) in advance, and can switch the vehicle from natural sliding to motor braking at the theoretical CR switching point, namely the deceleration time is proper, so that the influence on the vehicle oil consumption and the vehicle experience caused by too early or too late braking behavior due to the fact that the deceleration time cannot be accurately judged is effectively avoided.
Therefore, different from the situation that the traditional vehicle control system cannot control the deceleration behavior and the deceleration process of the driver, the invention can decide the deceleration time according to the environmental information, remind the driver to release the throttle for deceleration and carry out the proper deceleration process according to different conditions. Unlike the control method with respect to a static target, the present invention takes into account the dynamic characteristics of the preceding vehicle, and can make a deceleration determination and a deceleration response to the dynamic target accordingly. The method can avoid unnecessary acceleration of the driver, reduce the oil injection of the engine during driving, avoid unnecessary friction braking process, maximally recover the vehicle kinetic energy during the deceleration process, and improve the oil consumption of the whole vehicle. In addition, the invention can make up the defect that the static target deceleration control strategy method cannot solve the dynamic target.
The vehicle deceleration control method is suitable for vehicles provided with a motor, a power disconnecting device, a radar, a camera and navigation, wherein the motor can perform assistance or energy recovery; the power disconnecting device can realize the sliding function of the vehicle; radar, camera and navigation can acquire the forward environment information. The vehicle can be a hybrid electric vehicle or a pure electric vehicle. The vehicle slides freely in a way of disconnecting a clutch or neutral gear in the process of deceleration control, and energy is recovered through motor braking.
In another embodiment, a vehicle control unit is provided, which includes: a processor and a memory, the memory having stored therein a computer program; the processor executes the computer program stored in the memory to cause the vehicle control unit to execute the vehicle deceleration control method, so that the vehicle provided with the vehicle control unit performs deceleration control on the vehicle.
In summary, in the vehicle deceleration control method and the vehicle control unit provided by the present invention, for each time, first, whether the driver of the vehicle has an intention to decelerate is determined according to the vehicle speed of the vehicle at the corresponding time, the vehicle speed of the vehicle ahead, and the relative distance between the vehicle and the vehicle ahead; secondly, when a deceleration intention exists, whether the vehicle needs to be decelerated and driven is judged by calculating a braking distance required to be driven when the vehicle speed is braked to reach the vehicle speed in front after the throttle of the vehicle is released, a first deceleration distance required to be driven when the vehicle speed is completely slid to reach the vehicle speed in front and a second deceleration distance required to be driven when the vehicle speed is completely braked to reach the vehicle speed in front through a motor, and a deceleration mode adopted when the vehicle needs to be decelerated and driven is determined; and finally, performing deceleration control on the vehicle at different deceleration stages according to the determined deceleration mode and the mode of taking over control by the driver, so that the vehicle can perform sliding and motor braking recovery actions, and better fuel economy and driving safety are realized.
The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.

Claims (12)

1. A vehicle deceleration control method adapted to a dynamic environment, comprising:
acquiring the speed of the vehicle, the speed of the vehicle in front and the relative distance between the vehicle and the vehicle in front in real time;
judging whether the driver of the vehicle has a deceleration intention or not according to the vehicle speed of the vehicle at the current moment, the vehicle speed of the vehicle in front and the relative distance between the vehicle and the vehicle in front at each moment;
when the judgment result shows that the driver of the vehicle has the deceleration intention, respectively calculating the first time (t) required for the vehicle to completely slide to reach the vehicle speed of the front vehicle at the vehicle speed after the throttle of the vehicle is releasedc) And a first deceleration distance(s) traveledc) And a second time (t) required for full motor braking at the speed of the vehicle to reach the speed of the vehicle aheadr) And a second deceleration distance(s) traveledr)；
Calculating the braking distance(s) required to be traveled when the speed of the vehicle is braked to reach the speed of the vehicle in front after the throttle of the vehicle is releasedsum)；
According to the braking distance, the first deceleration distance(s)c) And the second deceleration distance(s)r) Judging whether the vehicle needs to be decelerated and driven, and determining a deceleration mode adopted when the vehicle needs to be decelerated and driven;
prompting the driver of the vehicle to release the accelerator after judging that the vehicle needs to run at a reduced speed;
and after the accelerator is released by the driver of the vehicle, performing vehicle deceleration control according to the deceleration mode until the vehicle speed is decelerated to reach a vehicle speed threshold value and/or the relative distance between the driver of the vehicle and the front vehicle reaches a distance threshold value, and prompting the driver of the vehicle to take over the vehicle deceleration control.
2. The vehicle deceleration control method according to claim 1, characterized in that the vehicle speed of the preceding vehicle and the relative distance of the own vehicle from the preceding vehicle are acquired based on radar monitoring of the own vehicle arrangement.
3. The vehicle deceleration control method according to claim 1, wherein said process of determining whether the driver of the own vehicle has an intention to decelerate based on the speed of the own vehicle, the speed of the preceding vehicle, and the relative distance between the own vehicle and the preceding vehicle at the present time for each time is as follows:
judging whether the relative speed of the vehicle and the front vehicle at the current moment is smaller than a relative speed threshold value and whether the relative distance is smaller than a relative distance threshold value; if the relative speed is smaller than the relative speed threshold value and the relative distance is smaller than the relative distance threshold value, the driver of the vehicle has a deceleration intention; otherwise, the driver of the vehicle has no intention of deceleration.
4. The vehicle deceleration control method according to claim 1, characterized in that the first deceleration distance(s) is calculatedc) The second deceleration distance(s)r) The first time (t)c) And said second time (t)r) The following formula is adopted:
Figure FDA0002804697280000021
in the formula (1), FrIs the vehicle sliding resistance related to the vehicle speed v; mdragIs equal to the engine speed neThe associated engine drag torque; mgenIs equal to the motor speed nmThe associated motor braking torque; η is the efficiency of the relevant component; i.e. ioThe engine main reduction ratio; i.e. igIs the engine gear ratio; m is the vehicle mass; delta is a vehicle rotation conversion coefficient;
Figure FDA0002804697280000022
when the engine speed and the motor speed are in a fixed gear, the engine speed and the motor speed are in a proportional relation with the vehicle speed, so that the formula (1) is converted into the following formula:
Figure FDA0002804697280000023
Figure FDA0002804697280000024
Figure FDA0002804697280000025
in the formulae (3) and (4), scA first deceleration distance; srA second deceleration distance; v. of0The speed of the vehicle is the speed of the vehicle when the accelerator is loosened; v is the speed of the vehicle; v. oftIs the forward vehicle speed.
5. The vehicle deceleration control method according to claim 4, wherein the calculation of the braking distance that the vehicle speed brake of the host vehicle needs to travel to reach the vehicle speed of the vehicle ahead after the throttle of the host vehicle is released is performed using the following equation:
ssum＝s0+sm (5)；
in the formula (5), ssumIs the braking distance; s0The relative distance between the vehicle and the front vehicle when the vehicle releases the throttle; sm is the distance traveled by the preceding vehicle at the first time or the distance traveled by the preceding vehicle at the second time.
6. Vehicle deceleration control method according to claim 5, characterized in that said braking distance(s) is dependent onsum) The first deceleration distance(s)c) And the second deceleration distance(s)r) The basis for judging whether the vehicle needs to run at a reduced speed is as follows:
determining the braking distance(s)sum) Whether or not it is less than the first deceleration distance(s)c) If yes, the vehicle needs to run at a reduced speed; on the contrary, the vehicle does not need to run at a reduced speed.
7. The vehicle deceleration control method according to claim 6, characterized in that the basis for determining the deceleration mode to be employed when deceleration running is required is as follows:
Figure FDA0002804697280000026
the CR mode is a control mode of firstly sliding and then braking and decelerating the motor; the FR mode is a complete motor braking deceleration control mode; ssumIs the braking distance; scA first deceleration distance; srIs the second deceleration distance.
8. The vehicle deceleration control method according to claim 7, wherein, in the process of performing the vehicle deceleration control in the FR mode, the vehicle control unit performs the motor torque adjustment according to a difference between a relative distance between the vehicle and the vehicle ahead actually acquired at each moment after the vehicle is released from the throttle and a theoretical relative distance between the vehicle and the vehicle ahead at the corresponding moment;
wherein the theoretical relative distance calculation formula is as follows:
slact＝sr-snow＝sr-(∫vfr(v，ig)dv+C(s0，vt))；
wherein s islactTheoretical relative distance; srA second deceleration distance; snowThe running distance of the vehicle; s0Is a vehicleThe relative distance between the vehicle and the front vehicle when the vehicle releases the throttle; v. oftThe speed of the vehicle ahead of the moment when the throttle of the vehicle is released; c is a group s0And vtA determined constant term; i.e. igIs the engine gear ratio.
9. A vehicle deceleration control method according to claim 1, characterized in that the driver of the vehicle is prompted to release the throttle based on a double pulse vibration pattern of an active feedback pedal (APM) as a warning means.
10. The vehicle deceleration control method according to claim 1, wherein the driver of the own vehicle is prompted to take over the vehicle deceleration control based on an automobile instrument Human Machine Interface (HMI).
11. The vehicle deceleration control method according to claim 1, characterized in that the vehicle speed threshold value is related to a preceding vehicle speed and a host vehicle idle speed; the distance threshold is related to the speed of the vehicle, the gear of the vehicle and the speed of the vehicle in front.
12. A vehicle control unit, comprising: a processor and a memory, the memory having stored therein a computer program; the processor executes the computer program stored in the memory to cause the hybrid vehicle controller to execute the vehicle deceleration control method according to any one of claims 1 to 11.
CN202011367385.7A 2020-11-27 2020-11-27 Vehicle deceleration control method and vehicle control unit Pending CN112455436A (en)

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