CN114954391A - Vehicle driving road surface recognition method and vehicle - Google Patents
Vehicle driving road surface recognition method and vehicle Download PDFInfo
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- CN114954391A CN114954391A CN202110217816.XA CN202110217816A CN114954391A CN 114954391 A CN114954391 A CN 114954391A CN 202110217816 A CN202110217816 A CN 202110217816A CN 114954391 A CN114954391 A CN 114954391A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/17—Using electrical or electronic regulation means to control braking
- B60T8/171—Detecting parameters used in the regulation; Measuring values used in the regulation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/17—Using electrical or electronic regulation means to control braking
- B60T8/176—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS
- B60T8/1763—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS responsive to the coefficient of friction between the wheels and the ground surface
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- 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
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/72—Electric energy management in electromobility
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Abstract
The invention discloses a vehicle running road surface recognition method and a vehicle, wherein the method comprises the steps of acquiring a wheel speed signal, a vehicle speed signal and the current control state of an anti-lock braking system of the vehicle when the vehicle is determined to be in a braking state according to a brake pedal signal of the vehicle acquired in real time; determining a to-be-switched control state of an anti-lock system according to a wheel speed signal and a vehicle speed signal, and controlling the vehicle to be switched from the current control state to the to-be-switched control state when the to-be-switched control state is different from the current control state; acquiring a pressure value of a supporting wheel cylinder when the vehicle is switched from a current control state to a control state to be switched; and when the current control state is a non-pressure-relief state and the control state to be switched is a pressure-relief state, determining the current friction coefficient of the road where the vehicle is located currently according to the pressure value of the branch wheel cylinder so as to obtain a road surface identification result according to the friction coefficient. The method improves the accuracy and speed of obtaining the friction coefficient of the road surface and improves the accuracy of road surface identification.
Description
Technical Field
The invention relates to the technical field of road surface identification, in particular to a method for identifying a running road surface of a vehicle and the vehicle.
Background
With the rapid development of society, the safety performance requirements of vehicles are higher and higher. ABS (Anti-lock Braking System) plays an important role in vehicle safety systems, and the accuracy of the road surface identification algorithm in ABS determines the performance effect of ABS.
In the prior art, there is a scheme of acquiring a theoretical wheel angle deceleration through a tire friction model and a vehicle single-wheel model, comparing the theoretical wheel angle deceleration with an actual wheel angle deceleration, determining a road surface friction coefficient according to the theoretical wheel angle deceleration closest to the actual wheel angle deceleration, and then performing road surface identification. The method has the following defects: the accuracy of obtaining the road surface friction coefficient through the tire friction model is low, so that the accuracy of road surface identification is low, the performance of the ABS is reduced, and the safety of a vehicle is reduced.
Disclosure of Invention
The embodiment of the invention provides a method for identifying a running road surface of a vehicle and the vehicle, and aims to solve the problem of low road surface identification accuracy rate in the prior art.
A vehicle travel surface recognition method comprising:
when the vehicle is determined to be in a braking state according to a brake pedal signal of the vehicle acquired in real time, acquiring a wheel speed signal and a vehicle speed signal of the vehicle and a current control state of an anti-lock system of the vehicle;
determining a to-be-switched control state of the anti-lock system according to the wheel speed signal and the vehicle speed signal, and controlling the anti-lock system to be switched from the current control state to the to-be-switched control state when the to-be-switched control state is different from the current control state;
acquiring a supporting wheel cylinder pressure value of the vehicle when the anti-lock system is switched from the current control state to the control state to be switched;
and when the control state to be switched is the pressure relief state and the current control state is the non-pressure relief state, determining the current friction coefficient of the road where the vehicle is currently located according to the pressure value of the branch wheel cylinder, so as to obtain a road identification result according to the current friction coefficient.
A vehicle includes a controller for executing the above-described vehicle travel surface recognition method.
The method for identifying the running road surface of the vehicle comprises the steps of acquiring a wheel speed signal and a vehicle speed signal of the vehicle and a current control state of an anti-lock braking system of the vehicle when the vehicle is determined to be in a braking state according to a brake pedal signal of the vehicle acquired in real time; determining a to-be-switched control state of the anti-lock system according to the wheel speed signal and the vehicle speed signal, and controlling the anti-lock system to be switched from the current control state to the to-be-switched control state when the to-be-switched control state is different from the current control state; acquiring a supporting wheel cylinder pressure value of the vehicle when the anti-lock system is switched from the current control state to the control state to be switched; and when the control state to be switched is the pressure relief state and the current control state is the non-pressure relief state, determining the current friction coefficient of the road where the vehicle is currently located according to the pressure value of the branch wheel cylinder, so as to obtain a road identification result according to the current friction coefficient.
When the vehicle is in a braking state, the to-be-switched control state of the anti-lock system is determined according to the wheel speed signal and the vehicle speed signal, when the current control state of the anti-lock system is in a non-pressure-relief state, and the to-be-switched control state is in a pressure-relief state, the current friction coefficient of the road where the vehicle is located at present is determined by obtaining the pressure value of the wheel supporting cylinder obtained in the switching process of the control state of the anti-lock system, and then the road identification result is obtained according to the current friction coefficient.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments of the present invention will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without inventive labor.
FIG. 1 is a flow chart of a method for identifying a driving surface of a vehicle according to an embodiment of the present invention;
FIG. 2 is a flowchart of step S40 in the method for identifying a driving surface of a vehicle according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a preset supporting cylinder pressure curve in the method for identifying a driving road surface of a vehicle according to an embodiment of the invention;
fig. 4 is another flowchart of a method for identifying a driving surface of a vehicle according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In one embodiment, as shown in fig. 1, there is provided a method for identifying a driving surface of a vehicle, including the steps of:
s10: when the vehicle is determined to be in a braking state according to the brake pedal signal of the vehicle acquired in real time, acquiring a wheel speed signal and a vehicle speed signal of the vehicle and a current control state of an anti-lock system of the vehicle.
It is understood that the brake pedal signal refers to a signal generated when a pedal of the vehicle is depressed to a certain depth, and can be used for indicating whether the vehicle is in a braking state or not. The wheel speed signal is a speed signal of the rotation of the wheel of the vehicle. The vehicle speed signal indicates the current running speed of the vehicle as displayed in a vehicle speed dial.
Further, the current control state refers to a state that an anti-lock brake system of the vehicle is currently recorded, and the current control state refers to a state that the vehicle enters after being in a braking state last time, and for example, the current control state of the anti-lock brake system may include, but is not limited to, any one of an initial state, a pressurization state, a pressure maintaining state, and a pressure relief state. Wherein the initial state refers to a state when the vehicle anti-lock system is triggered for the first time; the pressure relief state refers to a state when the wheels tend to be locked under the condition that the wheel slip rate of the vehicle is large; the pressure maintaining state refers to a state when a wheel speed signal of the vehicle is restored to be close to a vehicle speed signal of the vehicle after the anti-lock system is in a pressure relief state; the supercharging state refers to a process that after the anti-lock system passes through the pressure maintaining state, the wheel speed signal of the vehicle is restored to be close to the vehicle speed signal of the vehicle, and the supercharging needs to be carried out again.
In one embodiment, in step S10, the determining that the vehicle is in a braking state according to the brake pedal signal of the vehicle obtained in real time includes:
the method comprises the steps of acquiring a pedal depth corresponding to a brake pedal signal after the brake pedal signal of a vehicle is acquired in real time, and determining that the vehicle is in a braking state when the pedal depth is greater than or equal to a preset pedal depth threshold value.
It can be understood that the brake pedal signal includes a pedal depth of a pedal of the vehicle, and when the pedal depth is greater than or equal to a preset pedal depth threshold value, it is determined that the vehicle is currently in a braking state; if the pedal depth is less than the preset pedal depth threshold value, the vehicle is determined to be in a non-braking state currently. Optionally, the preset pedal depth threshold may be 0, 5%, 10%, etc.; for example, when a driver accidentally touches the brake pedal during driving of the vehicle, the depth change of the brake pedal is small, and the vehicle does not enter the braking state. Further, the preset pedal depth threshold may be set according to specific situations, such as when the braking state is an emergency braking state, the preset pedal depth threshold may be 90% of the pedal height.
Further, the vehicle travel surface identification method further includes:
and when the vehicle is determined to be in a non-braking state according to the brake pedal signal of the vehicle acquired in real time, acquiring the current control state of an anti-lock braking system of the vehicle.
And when the current control state is not the initial state, controlling the anti-lock system to switch from the current control state to the initial state, and recording an initial friction coefficient corresponding to the initial state as a current friction coefficient.
It can be understood that when the vehicle is determined to be in a non-braking state according to the brake pedal signal of the vehicle obtained in real time, that is, when it is detected that the pedal depth corresponding to the brake pedal signal is equal to zero, it is determined that the vehicle is not in a braking state at present, and at this time, the anti-lock system of the vehicle does not need to perform pressurization, pressure maintaining or pressure relief and the like, so that at this time, the current control state of the anti-lock system of the vehicle needs to be obtained, and whether the current control state is the initial state or not is judged, and if the current control state is not the initial state, the anti-lock system is controlled to be switched from the current control state to the initial state, and the initial friction coefficient corresponding to the initial state is recorded as the current friction coefficient; and if the current control state is the initial state, keeping the current control state of the anti-lock system unchanged.
S20: and determining a to-be-switched control state of the anti-lock system according to the wheel speed signal and the vehicle speed signal, and controlling the anti-lock system to be switched from the current control state to the to-be-switched control state when the to-be-switched control state is different from the current control state.
The control state to be switched refers to a control state which is determined according to the wheel speed signal and the vehicle speed signal and is required to be entered by an anti-lock braking system of the vehicle at present.
Specifically, when the vehicle is determined to be in a braking state according to a brake pedal signal of the vehicle acquired in real time, after a wheel speed signal, a vehicle speed signal and a current control state of an anti-lock system of the vehicle are acquired, a to-be-switched state (such as an initial state, a pressurization state, a pressure maintaining state or a pressure relief state) of the anti-lock system is determined according to the wheel speed signal and the vehicle speed signal, whether the to-be-switched control state is different from the current control state is determined, and then when the to-be-switched state is different from the current control state, the anti-lock system is controlled to be switched from the current control state to the to-be-switched control state; and when the state to be switched is the same as the current control state, keeping the current control state of the anti-lock system unchanged.
S30: and acquiring a supporting wheel cylinder pressure value of the vehicle when the anti-lock system is switched from the current control state to the control state to be switched.
As will be understood, the wheel cylinder pressure value refers to a wheel cylinder pressure value of a brake of the vehicle, which can be measured by a pressure sensor provided on the brake.
S40: and when the control state to be switched is a pressure relief state and the current control state is a non-pressure relief state, determining the current friction coefficient of the road where the vehicle is currently located according to the pressure value of the branch wheel cylinder, so as to obtain a road identification result according to the friction coefficient.
As can be appreciated, the current coefficient of friction is used to characterize the smoothness of the road surface on which the vehicle is currently located. Further, since the current control state of the abs may include any one of an initial state, a pressurized state, a pressure maintaining state and a pressure relief state, the non-pressure relief state is any one of the initial state, the pressurized state and the pressure maintaining state except the pressure relief state.
Specifically, after the pressure value of the supporting wheel cylinder when the vehicle is switched from the current control state to the control state to be switched is obtained, whether the current control state is a non-pressure-relief state is judged, that is, whether the current control state is any one of an initial state, a pressurization state and a pressure-maintaining state is judged; meanwhile, whether the control state to be switched is a pressure relief state or not needs to be judged. When the current control state is a non-pressure-relief state and the control state to be switched is a pressure-relief state, determining the current friction coefficient of the road where the vehicle is currently located according to the pressure value of the branch wheel cylinder, obtaining a road identification result according to the current friction coefficient, and matching the current friction coefficient with a preset friction coefficient table (storing friction coefficient ranges corresponding to different roads in the preset friction coefficient table) after determining the current friction coefficient of the road where the vehicle is currently located, so as to take the road corresponding to the friction range matched with the current friction coefficient as the road identification result; in addition, the control parameters of the anti-lock braking system can be adjusted according to the current friction coefficient, for example, when the current friction coefficient is higher (for example, the current friction coefficient is 0.6), and the to-be-switched control state is a pressure relief state, pressure relief can be performed according to a preset pressure relief amount; when the current friction coefficient is low (if the current friction coefficient is 0.18), continuously performing pressure relief operation until the pressure relief is stopped after the locking of the anti-lock system is finished; for another example, when the current friction coefficient is high, if the control state to be switched is a pressurization state, the pressurization rate corresponding to the pressurization state can be reduced; when the current friction coefficient is low, if the control state to be switched is a supercharging state, the supercharging speed corresponding to the supercharging state can be increased. The road surface identification result represents the current road surface condition of the vehicle, and exemplarily, the road surface identification result may be wet land, dry land, ice land, snow land and the like, that is, after the current friction coefficient of the current road surface of the vehicle is determined, the smoothness degree of the current road surface may be determined according to the friction coefficient, so as to adjust the wheel speed signal and the vehicle speed signal of the vehicle better and improve the driving safety of the vehicle.
In this embodiment, when the vehicle is in a braking state, a to-be-switched control state of the anti-lock system is determined according to the wheel speed signal and the vehicle speed signal, when the current control state of the anti-lock system is a non-pressure-relief state, and the to-be-switched control state is a pressure-relief state, the current friction coefficient of the road where the vehicle is located at present is determined by obtaining the pressure value of the wheel supporting cylinder obtained in the switching process of the control state of the anti-lock system, and then the road identification result is obtained according to the current friction coefficient.
In an embodiment, the step S20, namely, the acquiring the wheel speed signal and the vehicle speed signal of the vehicle, includes:
and determining the single-wheel slip rate of the vehicle according to the vehicle speed signal and the wheel speed signal.
It will be appreciated that the grip of the tires of the vehicle after the vehicle is in a braking condition may be manifested by a single wheel slip ratio. That is, the larger the single wheel slip rate is, the lower the friction coefficient of the road surface where the vehicle is located at present is represented, and the grip performance of the vehicle is poor.
Specifically, when the vehicle is determined to be in a braking state according to a brake pedal signal of the vehicle acquired in real time, after a wheel speed signal and a vehicle speed signal of the vehicle are acquired, a difference between the vehicle speed signal and the wheel speed signal is recorded as a speed signal difference, and then a ratio between the speed signal difference and the vehicle speed signal is recorded as a single wheel slip rate.
Determining a wheel speed deceleration of the vehicle based on the wheel speed signal and a wheel speed time corresponding to the wheel speed signal.
It is understood that the wheel speed deceleration represents a rate of decrease in the wheel rotational speed in the wheel speed signal after the vehicle enters a braking state. The wheel speed time refers to a time length corresponding to a process that the wheel rotation speed is reduced from the beginning to the non-reduction state in the wheel speed signal after the vehicle enters the braking state, and the wheel speed time can be detected by a timer installed on the vehicle, namely, a time point that the wheel rotation speed begins to be reduced and a time point that the wheel rotation speed is not reduced any more are obtained, and then a time length difference value between the two time points is recorded as the wheel speed time.
Specifically, when the vehicle is determined to be in a braking state according to a brake pedal signal of the vehicle acquired in real time, after a wheel speed signal and a vehicle speed signal of the vehicle are acquired, a ratio between the wheel speed signal and a wheel speed time is recorded as a wheel speed deceleration.
In an embodiment, the step S20 of determining the state of control to be switched with the anti-lock braking system according to the wheel speed signal and the vehicle speed signal includes:
when the single wheel slip rate and the wheel speed deceleration meet a preset pressure relief requirement, determining that the control state to be switched is a pressure relief state, wherein the preset pressure relief requirement is that the single wheel slip rate is greater than a preset first slip rate threshold value, or the wheel speed deceleration is greater than a preset first wheel speed deceleration threshold value.
Alternatively, the preset first slip rate threshold may be 30%; the preset first wheel speed deceleration threshold may be-20 m/s 2 。
Specifically, after determining the single wheel slip rate of the vehicle according to the vehicle speed signal and the wheel speed signal, and determining the wheel speed deceleration of the vehicle according to the wheel speed signal and the wheel speed time corresponding to the wheel speed signal, comparing the single wheel slip rate with a preset first slip rate threshold, and comparing the wheel speed deceleration with a preset first wheel speed deceleration threshold, when the single wheel slip rate is greater than the preset first slip rate threshold, or the wheel speed deceleration is greater than the preset first wheel speed deceleration threshold, determining that the single wheel slip rate and the wheel speed deceleration meet a preset pressure release requirement, and further determining that the anti-lock system should enter a pressure release state at this time, that is, the to-be-switched control state is the pressure release state.
In one embodiment, in step S20, the determining the to-be-switched control state of the anti-lock braking system according to the wheel speed signal and the vehicle speed signal further includes:
when the single wheel slip rate or the wheel speed deceleration meets the preset pressure maintaining requirement, determining that the control state to be switched is a pressure maintaining state; the preset pressure maintaining requirement is as follows: the single-wheel slip rate is less than or equal to a preset first slip rate threshold value and greater than a preset second slip rate threshold value; the preset second slip rate threshold value is smaller than the preset first slip rate threshold value; or alternatively
The wheel speed deceleration is less than or equal to a preset first wheel speed deceleration threshold and greater than a preset second wheel speed deceleration threshold; the preset second wheel speed deceleration threshold is less than the preset first wheel speed deceleration threshold.
Alternatively, the preset second slip rate threshold may be 10%; the preset second wheel speed deceleration threshold may be-25 m/s 2 。
On one hand, after the single wheel slip rate of the vehicle is determined according to the vehicle speed signal and the wheel speed signal, the single wheel slip rate is compared with a preset first slip rate threshold value, when the single wheel slip rate is smaller than or equal to the preset first slip rate threshold value, the single wheel slip rate is compared with a preset second slip rate threshold value, when the single wheel slip rate is larger than the preset second slip rate threshold value, the single wheel slip rate is determined to meet the preset pressure maintaining requirement, and then the anti-lock system is determined to enter the pressure maintaining state at the moment, namely the to-be-switched control state is the pressure maintaining state.
On the other hand, after the wheel speed deceleration of the vehicle is determined according to the wheel speed signal and the wheel speed time corresponding to the wheel speed signal, the wheel speed deceleration is compared with a preset first wheel speed deceleration threshold value, when the wheel speed deceleration is smaller than or equal to the preset first wheel speed deceleration threshold value, the wheel speed deceleration is compared with a preset second wheel speed deceleration threshold value, when the wheel speed deceleration is larger than the preset second wheel speed deceleration threshold value, the wheel speed deceleration is determined to meet a preset pressure maintaining requirement, and then the anti-lock system is determined to be in a pressure maintaining state at the moment, namely the control state to be switched is in the pressure maintaining state.
In an embodiment, in step S20, the determining the to-be-switched control state of the anti-lock braking system according to the wheel speed signal and the vehicle speed signal further includes:
when the single wheel slip rate or the wheel speed deceleration meets a preset supercharging requirement, determining that the control state to be switched is a supercharging state; the preset supercharging requirement is as follows: the single-wheel slip rate is less than or equal to a preset second slip rate threshold value and greater than a preset third slip rate threshold value; the preset third slip rate threshold value is smaller than the preset second slip rate threshold value; or
The wheel speed deceleration is less than or equal to a preset second wheel speed deceleration threshold value and greater than a preset third wheel speed deceleration threshold value; the preset third wheel speed deceleration threshold is less than the preset second wheel speed deceleration threshold. Alternatively, the preset third slip rate threshold may be 2% or 3%; the preset second wheel speed deceleration threshold may be-30 m/s 2 。
On one hand, after determining the single wheel slip rate of the vehicle according to the vehicle speed signal and the wheel speed signal, comparing the single wheel slip rate with a preset first slip rate threshold value and a preset second slip rate threshold value, when the single wheel slip rate is smaller than or equal to the preset second slip rate threshold value, comparing the single wheel slip rate with a preset third slip rate threshold value, when the single wheel slip rate is larger than the preset third slip rate threshold value, determining that the single wheel slip rate meets the preset supercharging requirement, and further determining that the anti-lock system should enter a supercharging state at the moment, namely the to-be-switched control state is the supercharging state.
On the other hand, after the wheel speed deceleration of the vehicle is determined according to the wheel speed signal and the wheel speed time corresponding to the wheel speed signal, when the wheel speed deceleration is smaller than or equal to the preset second wheel speed deceleration threshold, the wheel speed deceleration is compared with the preset third wheel speed deceleration threshold, when the wheel speed deceleration is larger than the preset third wheel speed deceleration threshold, the wheel speed deceleration is determined to meet the preset boosting requirement, and then the anti-lock system is determined to be in the boosting state at the moment, namely the control state to be switched is the boosting state.
In an embodiment, in step S20, the determining the to-be-switched control state of the anti-lock braking system according to the wheel speed signal and the vehicle speed signal further includes:
when the single wheel slip rate and the wheel speed deceleration meet a preset exit control requirement, controlling the vehicle to exit the current control state; the preset exit control requirement is that the single wheel slip ratio is less than or equal to a preset third slip ratio threshold or the wheel speed deceleration is less than or equal to a preset third wheel speed deceleration threshold.
Specifically, after determining the single wheel slip rate of the vehicle according to the vehicle speed signal and the wheel speed signal, and determining the wheel speed deceleration of the vehicle according to the wheel speed signal and the wheel speed time corresponding to the wheel speed signal, comparing the single wheel slip rate with a preset first slip rate threshold, a preset second slip rate threshold and a preset third slip rate threshold, and comparing the wheel speed deceleration with a preset first wheel speed deceleration threshold, a preset second wheel speed deceleration threshold and a preset third wheel speed deceleration threshold, when the single wheel slip rate is less than or equal to the preset third slip rate threshold, or the wheel speed deceleration is less than or equal to the preset third wheel speed deceleration threshold, controlling the anti-lock system to exit the current control state, and at this time, controlling the anti-lock system to switch to the initial state.
In one embodiment, as shown in fig. 2, the step S40 of determining the current friction coefficient of the road where the vehicle is currently located according to the pressure value of the wheel supporting cylinder includes:
s401: acquiring a preset pressure coefficient associated with a pressure value of a supporting wheel cylinder from a preset supporting wheel cylinder pressure curve; and the preset branch wheel cylinder pressure curve represents the incidence relation between a preset branch wheel cylinder pressure value and a preset pressure coefficient corresponding to the preset branch wheel cylinder pressure value.
The preset supporting wheel cylinder pressure curve can be represented by a curve shown in fig. 3, in the coordinate system in fig. 3, the abscissa is the preset supporting wheel cylinder pressure value, and the ordinate is the preset pressure coefficient, understandably, the preset supporting wheel cylinder pressure curve is obtained by testing a simulation experiment on an anti-lock braking system of a vehicle, the preset supporting wheel cylinder pressure curve represents the incidence relation between the preset supporting wheel cylinder pressure value and the preset pressure coefficient corresponding to the preset supporting wheel cylinder pressure value, that is, the preset supporting wheel cylinder pressure value and the preset pressure coefficient are preset values obtained by performing a simulation experiment on the anti-lock braking system of the vehicle, and the product of the preset supporting wheel cylinder pressure value and the preset pressure coefficient is used for representing the friction coefficient between the vehicle wheel and a road surface. Optionally, the preset pressure coefficient is stored in percentage in a preset strut cylinder pressure curve.
Specifically, when the current control state is a non-pressure-relief state and the control state to be switched is a pressure-relief state, a preset supporting wheel cylinder pressure value corresponding to the supporting wheel cylinder pressure value is determined from a preset supporting wheel cylinder pressure curve, and then a preset pressure coefficient corresponding to the preset supporting wheel cylinder pressure value is used as a preset pressure coefficient corresponding to the supporting wheel cylinder pressure value when the vehicle is switched from the current control state to the control state to be switched.
S402: and recording the product of the pressure value of the branch wheel cylinder and the obtained preset pressure coefficient as the current friction coefficient of the road where the vehicle is located at present.
Specifically, after a preset pressure coefficient associated with a pressure value of the wheel cylinder is obtained from a preset wheel cylinder pressure curve, the product of the pressure value of the wheel cylinder and the obtained preset pressure coefficient is recorded as the current friction coefficient of the road where the vehicle is located currently, and then a road surface identification result is obtained according to the current friction coefficient.
In an embodiment, as shown in fig. 4, after the step S30, that is, after obtaining the pressure value of the supporting roller when the vehicle is switched from the current control state to the control state to be switched, the method further includes:
s50: and when the control state to be switched is a non-pressure-relief state, or the control state to be switched is the pressure-relief state and the current control state is the pressure-relief state, acquiring a historical friction coefficient corresponding to the current control state.
It is understood that the historical friction coefficient refers to the friction coefficient corresponding to the current control state, i.e., the friction coefficient corresponding to the time the vehicle entered the current control state after the last braking state.
S60: recording an absolute value of a difference between the wheel cylinder pressure value and the historical friction coefficient as a friction difference value.
S70: and when the friction difference value is larger than or equal to the preset friction threshold value, determining the current friction coefficient of the road where the vehicle is located according to the pressure value of the branch wheel cylinder.
Alternatively, the preset friction threshold is set according to requirements, and for example, may be preferably 0.3, 0.4, and the like.
It can be understood that, when the current control state is a non-pressure-release state (i.e., one of an initial state, a pressure-increase state and a pressure-maintaining state), and the control state to be switched is a pressure-release state, the pressure value of the branch wheel cylinder obtained at this time is the pressure peak value of the branch wheel cylinder, so that the current friction coefficient of the road where the vehicle is currently located can be directly determined according to the pressure value of the branch wheel cylinder at this time; when the control state to be switched is a non-pressure relief state, namely the control state to be switched is a pressure relief state; or when the control state to be switched is a pressure relief state and the current control state is also the pressure relief state, the current friction coefficient of the current road surface of the vehicle cannot be directly determined according to the pressure value of the branch wheel cylinder, so that a historical friction coefficient corresponding to the current control state needs to be obtained, the absolute value of the difference value between the pressure value of the branch wheel cylinder and the historical friction coefficient is recorded as a friction difference value, and the friction difference value is compared with a preset friction threshold value; when the friction difference value is larger than or equal to the preset friction threshold value, the representation can directly determine the current friction coefficient of the road where the vehicle is located according to the pressure value of the branch wheel cylinder.
S80: and when the friction difference value is smaller than the preset friction threshold value, recording the historical friction coefficient as the current friction coefficient.
Specifically, after a historical friction coefficient corresponding to the current control state is obtained, and an absolute value of a difference value between a pressure value of a branch wheel cylinder and the historical friction coefficient is recorded as a friction difference value, the friction difference value is compared with a preset friction threshold value, when the friction difference value is smaller than the preset friction threshold value, the representation cannot directly determine the current friction coefficient of the road where the vehicle is located according to the pressure value of the branch wheel cylinder, the historical friction coefficient is guaranteed to be unchanged, and the historical friction coefficient is recorded as the current friction coefficient.
In this embodiment, when the control state to be switched is a non-pressure-relief state, or the control state to be switched is a pressure-relief state, and the current control state is also a pressure-relief state, the current friction coefficient of the road where the vehicle is currently located cannot be determined according to the pressure value of the branch wheel cylinder, and then the determination is performed by introducing the preset friction threshold value, so that the accuracy of the determined current friction coefficient is improved, and the accuracy of road surface identification is further improved.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.
In one embodiment, a vehicle is provided that includes a controller for executing the method for identifying a road surface on which the vehicle is traveling in the above-described embodiments.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned division of the functional units and modules is illustrated, and in practical applications, the above-mentioned function distribution may be performed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-mentioned functions.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.
Claims (10)
1. A method for identifying a running surface of a vehicle, comprising:
when the vehicle is determined to be in a braking state according to a brake pedal signal of the vehicle acquired in real time, acquiring a wheel speed signal and a vehicle speed signal of the vehicle and a current control state of an anti-lock system of the vehicle;
determining a to-be-switched control state of the anti-lock system according to the wheel speed signal and the vehicle speed signal, and controlling the anti-lock system to be switched from the current control state to the to-be-switched control state when the to-be-switched control state is different from the current control state;
acquiring a supporting wheel cylinder pressure value of the vehicle when the anti-lock system is switched from the current control state to the control state to be switched;
and when the control state to be switched is a pressure relief state and the current control state is a non-pressure relief state, determining the current friction coefficient of the road where the vehicle is located at present according to the pressure value of the supporting wheel cylinder, and obtaining a road surface identification result according to the current friction coefficient.
2. The method for identifying a running surface of a vehicle according to claim 1, wherein said acquiring a wheel speed signal, a vehicle speed signal of said vehicle comprises:
determining the single wheel slip rate of the vehicle according to the vehicle speed signal and the wheel speed signal;
determining a wheel speed deceleration of the vehicle based on the wheel speed signal and a wheel speed time corresponding to the wheel speed signal.
3. The method for identifying a running surface of a vehicle according to claim 2, wherein said determining a state of control to be switched with said antilock brake system based on said wheel speed signal and said vehicle speed signal comprises:
when the single wheel slip rate or the wheel speed deceleration meets a preset pressure relief requirement, determining that the control state to be switched is a pressure relief state, wherein the preset pressure relief requirement is as follows: the single wheel slip rate is greater than a preset first slip rate threshold value, or the wheel speed deceleration is greater than a preset first wheel speed deceleration threshold value.
4. The method for identifying a running surface of a vehicle according to claim 2, wherein said determining a state of control to be switched with said antilock brake system based on said wheel speed signal and said vehicle speed signal comprises:
when the single wheel slip rate or the wheel speed deceleration meets the preset pressure maintaining requirement, determining that the control state to be switched is a pressure maintaining state; the preset pressure maintaining requirement is as follows: the single-wheel slip rate is less than or equal to a preset first slip rate threshold value and greater than a preset second slip rate threshold value; the preset second slip rate threshold value is smaller than the preset first slip rate threshold value; or alternatively
The wheel speed deceleration is less than or equal to a preset first wheel speed deceleration threshold and greater than a preset second wheel speed deceleration threshold; the preset second wheel speed deceleration threshold is less than the preset first wheel speed deceleration threshold.
5. The method for identifying a running surface of a vehicle according to claim 2, wherein said determining a state of control to be switched with said antilock brake system based on said wheel speed signal and said vehicle speed signal comprises:
when the single-wheel slip rate or the wheel speed deceleration meets a preset supercharging requirement, determining that the control state to be switched is a supercharging state; the preset supercharging requirement is as follows: the single-wheel slip rate is less than or equal to a preset second slip rate threshold value and greater than a preset third slip rate threshold value; the preset third slip rate threshold value is smaller than the preset second slip rate threshold value; or
The wheel speed deceleration is less than or equal to a preset second wheel speed deceleration threshold and greater than a preset third wheel speed deceleration threshold; the preset third wheel speed deceleration threshold is less than the preset second wheel speed deceleration threshold.
6. The method for identifying a running surface of a vehicle according to claim 2, wherein said determining a state of control to be switched with said antilock brake system based on said wheel speed signal and said vehicle speed signal comprises:
when the single wheel slip rate or the wheel speed deceleration meets a preset exit control requirement, controlling the anti-lock braking system to exit the current control state; the preset exit control requirement is as follows: the single wheel slip rate is smaller than or equal to a preset third slip rate threshold value, or the wheel speed deceleration is smaller than or equal to a preset third wheel speed deceleration threshold value.
7. The method for identifying a running surface of a vehicle according to claim 1, wherein said determining a current friction coefficient of a surface on which the vehicle is currently located based on the wheel branch cylinder pressure value includes:
acquiring a preset pressure coefficient associated with a pressure value of a supporting wheel cylinder from a preset supporting wheel cylinder pressure curve; the preset branch wheel cylinder pressure curve represents the incidence relation between a preset branch wheel cylinder pressure value and a preset pressure coefficient corresponding to the preset branch wheel cylinder pressure value;
and recording the product of the pressure value of the branch wheel cylinder and the obtained preset pressure coefficient as the current friction coefficient of the road where the vehicle is located at present.
8. The method for identifying a running surface of a vehicle according to claim 1, wherein after obtaining the value of the pressure of the branch cylinder when the vehicle is switched from the current control state to the control state to be switched, the method comprises:
when the control state to be switched is a non-pressure-relief state or the control state to be switched and the current control state are both pressure-relief states, acquiring a historical friction coefficient corresponding to the current control state;
recording an absolute value of a difference between the bearing wheel cylinder pressure value and the historical friction coefficient as a friction difference value;
when the friction difference value is larger than or equal to a preset friction threshold value, determining the current friction coefficient of the road where the vehicle is located at present according to the pressure value of the branch wheel cylinder;
and when the friction difference value is smaller than the preset friction threshold value, recording the historical friction coefficient as the current friction coefficient, and obtaining a road surface identification result according to the current friction coefficient.
9. The vehicle travel surface identification method according to claim 1, characterized by further comprising:
when the vehicle is determined to be in a non-braking state according to a brake pedal signal of the vehicle acquired in real time, acquiring the current control state of an anti-lock braking system of the vehicle;
and when the current control state is not the initial state, controlling the vehicle to switch from the current control state to the initial state, recording an initial friction coefficient corresponding to the initial state as a current friction coefficient, and obtaining a road surface identification result according to the current friction coefficient.
10. A vehicle characterized by comprising a controller for executing a running surface recognition method of the vehicle according to any one of claims 1 to 9.
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| JPH09263226A (en) * | 1996-03-28 | 1997-10-07 | Toyota Motor Corp | Anti-lock control device |
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| CN109383469A (en) * | 2017-08-08 | 2019-02-26 | 比亚迪股份有限公司 | Calculation method, device and the automobile of optimal slip ratio |
| CN110660268A (en) * | 2018-06-29 | 2020-01-07 | 比亚迪股份有限公司 | Server, vehicle and safe driving method and system of vehicle |
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| JPH07144632A (en) * | 1993-11-25 | 1995-06-06 | Toyota Motor Corp | Antilock controller |
| JPH09263226A (en) * | 1996-03-28 | 1997-10-07 | Toyota Motor Corp | Anti-lock control device |
| CN101825510A (en) * | 2010-05-17 | 2010-09-08 | 北京航空航天大学 | Method for estimating brake pressure of automobile and peak value of road adhesion coefficient |
| CN109383469A (en) * | 2017-08-08 | 2019-02-26 | 比亚迪股份有限公司 | Calculation method, device and the automobile of optimal slip ratio |
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