CN111361533A - Anti-lock control method and device - Google Patents

Anti-lock control method and device Download PDF

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Publication number
CN111361533A
CN111361533A CN202010117018.5A CN202010117018A CN111361533A CN 111361533 A CN111361533 A CN 111361533A CN 202010117018 A CN202010117018 A CN 202010117018A CN 111361533 A CN111361533 A CN 111361533A
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China
Prior art keywords
wheel
wheel speed
displacement
motor
current
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CN202010117018.5A
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Chinese (zh)
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CN111361533B (en
Inventor
白银
秦民
郑磊
蔡丛
李同柱
黄胜龙
赵伟
蒋鑫
王星
李广奎
刘贵志
王新竹
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Suzhou Zhitu Technology Co Ltd
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Suzhou Zhitu Technology Co Ltd
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Priority to CN202010117018.5A priority Critical patent/CN111361533B/en
Publication of CN111361533A publication Critical patent/CN111361533A/en
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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
    • 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
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/74—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with electrical assistance or drive
    • B60T13/745—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with electrical assistance or drive acting on a hydraulic system, e.g. a master cylinder
    • 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
    • B60T8/172—Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters
    • 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
    • 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
    • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
    • B60T8/88—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration with failure responsive means, i.e. means for detecting and indicating faulty operation of the speed responsive control means
    • B60T8/92—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration with failure responsive means, i.e. means for detecting and indicating faulty operation of the speed responsive control means automatically taking corrective action
    • B60T8/96—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration with failure responsive means, i.e. means for detecting and indicating faulty operation of the speed responsive control means automatically taking corrective action on speed responsive control means

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Regulating Braking Force (AREA)

Abstract

The invention provides an anti-lock control method and device, wherein the anti-lock control method comprises the following steps: determining that an anti-lock brake system (ABS) is in a failure mode but the communication with the ABS is normal, and acquiring the wheel speed of a wheel; respectively determining a nominal vehicle speed, a wheel deceleration, a wheel speed vector and a slip degree corresponding to the current braking cycle based on the acquired wheel speed; and determining the current state of the wheel according to the slip degree, the wheel speed vector and the wheel deceleration, calculating the final motor target displacement according to the determined current state of the wheel and the preset mapping relation between the pedal displacement and the motor target displacement, and controlling the motor to operate to the final motor target displacement. The braking performance of the vehicle can be improved.

Description

Anti-lock control method and device
Technical Field
The invention relates to the technical field of an anti-lock Braking System (ABS) of a vehicle, in particular to an anti-lock control method and device.
Background
The safety performance of vehicles is always a focus of traffic travel. The ABS can effectively prevent wheels from being locked by braking in the braking process, improves the braking deceleration, shortens the braking distance, effectively improves the direction stability and the steering control capacity of a vehicle, is an anti-skid and anti-locking vehicle safety braking control system, is a main safety component for ensuring the safety performance, is concerned with, and is widely applied to the vehicle as a braking device.
The ABS sends out a signal that the wheel is locked through a sensor arranged on the wheel, after the controller receives the signal, the controller outputs an instruction to the regulator to reduce the oil pressure of a wheel brake cylinder, the braking torque is reduced, after a certain time, the original oil pressure is restored, and the continuous circulation is carried out, so that the wheel is always in a rotating state and has the maximum braking torque.
In order to further promote the safety performance of the vehicle and prevent the ABS from influencing the safety braking of the vehicle when the fault occurs, the electronic booster utilizes the electric energy by loading the electronic booster, the electric energy and the action signal are respectively transmitted through the electric wire and the signal wire, and the braking is more stable on the basis of meeting the braking effect and the driving safety by cooperating with the ABS. Taking ABS to break down as an example, on the vehicle of installing electronic booster, if ABS breaks down, then when emergency braking, the wheel can be in locking state, but because electronic booster can be through the displacement of control motor, thereby realize active control to master cylinder pressure, therefore, when ABS breaks down, active control can make master cylinder pressure and wheel cylinder pressure unanimous basically, when adjusting master cylinder pressure, can realize the regulation to wheel cylinder pressure, thereby utilize electronic booster's active pressure control, after ABS breaks down, adjust wheel pressure, prevent that the wheel from locking, avoid it to get into unstable operating mode.
However, in the active control method of the electronic booster, a blind control method of a master cylinder is adopted, namely, the displacement of a motor is controlled within a preset certain time so as to control the pressure rise of the master cylinder, so that braking is realized, and then the displacement of the motor is controlled within a certain time so as to control the pressure drop of the master cylinder, so that wheels are prevented from being locked, so that the pressure of the master cylinder is controlled in a circulating manner. However, in the active control method, the master cylinder pressure is increased or decreased according to a preset time period, the actual braking conditions are complicated and variable, when the wheel needs to be pressurized, the master cylinder is controlled to be depressurized by the active control method, and when the wheel needs to be depressurized, the master cylinder is controlled to be pressurized by the active control method, which is opposite to the expected control, so that the wheel is locked, and the braking performance of the vehicle is influenced.
Disclosure of Invention
In view of the above, the present invention provides an anti-lock control method and apparatus for improving braking performance of a vehicle.
In a first aspect, an embodiment of the present invention provides an anti-lock control method, including:
determining that an anti-lock brake system (ABS) is in a failure mode but the communication with the ABS is normal, and acquiring the wheel speed of a wheel;
respectively determining a nominal vehicle speed, a wheel deceleration, a wheel speed vector and a slip degree corresponding to the current braking cycle based on the acquired wheel speed;
and determining the current state of the wheel according to the slip degree, the wheel speed vector and the wheel deceleration, calculating the final motor target displacement according to the determined current state of the wheel and the preset mapping relation between the pedal displacement and the motor target displacement, and controlling the motor to operate to the final motor target displacement.
With reference to the first aspect, an embodiment of the present invention provides a first possible implementation manner of the first aspect, where the method further includes:
determining that the ABS is in a non-failure mode, and controlling according to a preset mapping relation between pedal displacement and motor target displacement;
recording the motor current and pedal displacement at the beginning of each ABS;
and carrying out mean value processing on the recorded motor current to obtain and store a motor current threshold value, and carrying out mean value processing on the recorded pedal displacement to obtain and store a pedal displacement threshold value.
With reference to the first aspect, an embodiment of the present invention provides a second possible implementation manner of the first aspect, where the method further includes:
determining that the ABS is in a fault mode and the communication between the ABS and the ABS is abnormal, and acquiring motor current and pedal displacement;
if the obtained motor current is larger than the stored motor current threshold value, or the obtained pedal displacement is larger than the stored pedal displacement threshold value, controlling the motor to keep the current displacement; otherwise, inquiring a preset mapping relation between the pedal displacement and the motor target displacement to obtain the motor target displacement mapped by the pedal displacement, and controlling the motor to operate to the obtained motor target displacement.
With reference to the first aspect, the example of the present invention provides a third possible implementation manner of the first aspect, where the determining a nominal vehicle speed corresponding to the current braking cycle includes:
determining the current braking cycle, and if the current braking cycle is the first braking cycle from the beginning of braking to the time when the wheels recover to the limit;
acquiring the initial wheel speed of wheel braking when ABS begins;
calculating a product of a preset first brake cycle deceleration and a control period corresponding to the first brake cycle, and a first difference value between the wheel braking initial wheel speed and the product;
and extracting the larger of the obtained wheel speed and the first difference value to obtain a nominal vehicle speed corresponding to the first brake cycle.
With reference to the third possible implementation manner of the first aspect, an embodiment of the present invention provides a fourth possible implementation manner of the first aspect, where the method further includes:
if the current braking cycle is not the first braking cycle;
obtaining the wheel braking starting wheel speed when the last braking cycle starts and the wheel recovery wheel speed when the limit is recovered;
acquiring the cycle time from the beginning of the last braking cycle to the time of recovering to the limit;
calculating a wheel speed difference between the wheel recovery wheel speed and a wheel braking start wheel speed, and calculating a deceleration ratio of the wheel speed difference to the cycle time;
calculating a second product of the deceleration ratio and a control period corresponding to the current braking cycle, and a second difference value of the wheel recovery wheel speed and the second product;
and extracting the larger of the obtained wheel speed and the second difference value to obtain the nominal vehicle speed corresponding to the current braking cycle.
With reference to the first aspect, the third possible implementation manner of the first aspect, or the fourth possible implementation manner, an embodiment of the present invention provides a fifth possible implementation manner of the first aspect, wherein the determining a current state of the wheel according to the slip degree, the wheel speed vector, and the wheel deceleration includes:
if the slip degree and the wheel deceleration meet a preset first condition, wherein the first condition is that the slip degree of any wheel is greater than a preset first slip degree threshold value, or the slip degree of any wheel is greater than a preset second slip degree threshold value and the wheel deceleration is less than a preset deceleration threshold value, determining that the wheel enters an unstable state, and marking the state to be 1, wherein the first slip degree threshold value is greater than the second slip degree threshold value;
and the motor target displacement mapped by the unstable state is equal to the difference value of the current displacement of the motor and the preset adjusting displacement.
With reference to the fifth possible implementation manner of the first aspect, an embodiment of the present invention provides a sixth possible implementation manner of the first aspect, where the method further includes:
if the slip degree and the wheel deceleration do not meet the preset first condition, judging whether the wheel speed vectors and the preset state marks meet the preset second condition, and if so, determining that the wheels enter a stable state, wherein the second condition is that the wheel speed vectors of all the wheels are default upward wheel speed vectors and the state marks are set to be 1;
and the motor target displacement mapped by the stable state is equal to the current displacement of the motor.
With reference to the sixth possible implementation manner of the first aspect, an embodiment of the present invention provides a seventh possible implementation manner of the first aspect, where the method further includes:
if the wheel speed vectors and the preset state marks do not meet the preset second condition, judging whether the slip degree, the wheel speed vectors and the preset state marks meet a preset third condition, and if so, determining that the wheels are all restored to the limit state, wherein the third condition is that the wheel speed vectors of all the wheels are default downward wheel speed vectors, the slip degree of all the wheels is smaller than a preset slip degree third threshold value and the state marks are set to be 1, and the slip degree third threshold value is smaller than a slip degree second threshold value;
and the motor target displacement mapped by the limit state is equal to the sum of the current displacement of the motor and the preset adjusting displacement.
With reference to the seventh possible implementation manner of the first aspect, an embodiment of the present invention provides an eighth possible implementation manner of the first aspect, where the method further includes:
if the slip degree, the wheel speed vector and the preset state mark do not meet the preset third condition, determining that the wheel does not enter an ABS state, and setting the state mark to be 0;
acquiring current pedal displacement;
and the motor target displacement which does not enter the ABS state mapping refers to the preset mapping relation between the pedal displacement and the motor target displacement.
In a second aspect, an embodiment of the present invention further provides an anti-lock control device, including:
the wheel speed acquisition module is used for determining that an anti-lock braking system ABS is in a failure mode but the communication with the ABS is normal and acquiring the wheel speed;
the calculation module is used for respectively determining a nominal vehicle speed, a wheel deceleration, a wheel speed vector and a slip degree corresponding to the current braking cycle based on the acquired wheel speed;
and the motor displacement control module is used for determining the current state of the wheel according to the slip degree, the wheel speed vector and the wheel deceleration, calculating the final motor target displacement according to the determined current state of the wheel and the preset mapping relation between the pedal displacement and the motor target displacement, and controlling the motor to operate to the final motor target displacement.
In a third aspect, an embodiment of the present application provides a computer device, which includes a memory, a processor, and a computer program stored on the memory and executable on the processor, and the processor implements the steps of the above method when executing the computer program.
In a fourth aspect, the present application provides a computer-readable storage medium, on which a computer program is stored, and the computer program, when executed by a processor, performs the steps of the method described above.
The embodiment of the invention provides an anti-lock control method and an anti-lock control device, wherein the anti-lock control method comprises the following steps: determining that an anti-lock brake system (ABS) is in a failure mode but the communication with the ABS is normal, and acquiring the wheel speed of a wheel; respectively determining a nominal vehicle speed, a wheel deceleration, a wheel speed vector and a slip degree corresponding to the current braking cycle based on the acquired wheel speed; and determining the current state of the wheel according to the slip degree, the wheel speed vector and the wheel deceleration, calculating the final motor target displacement according to the determined current state of the wheel and the preset mapping relation between the pedal displacement and the motor target displacement, and controlling the motor to operate to the final motor target displacement. Like this, but with electronic booster communication normal condition under the ABS trouble, confirm the wheel state through the wheel speed, according to the judgement to the wheel state, utilize electronic booster to carry out the target displacement control of motor of corresponding state, because the wheel speed can reflect actual braking operating mode, make braking control identical with actual braking operating mode, thereby can effectively avoid the wheel locking, promoted the brake performance of vehicle.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
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 embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a flow chart illustrating an anti-lock control method according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart illustrating a process for determining a nominal vehicle speed corresponding to a current braking cycle based on an obtained wheel speed according to an embodiment of the present invention;
FIG. 3 is a schematic flow chart illustrating a specific anti-lock control method according to an embodiment of the present invention;
FIG. 4 is a schematic view showing a construction of an anti-lock brake control apparatus according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a computer device 500 according to an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, 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 only a part of the embodiments of the present invention, and not all of the embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
According to the existing blind control method of the electronic booster, after the ABS fails, the displacement of the motor is controlled according to a preset time period, so that the pressure of a main cylinder is lifted to realize the braking of a vehicle, and the anti-lock is avoided. Based on this, according to the anti-lock control method and device provided in the embodiments of the present application, the braking information of the vehicle is obtained through the electronic booster and analyzed, so as to determine the current state of the wheel, and a corresponding braking control method is determined according to the determined current state of the wheel, so that the corresponding braking control method is matched with the actual braking condition cycle, thereby avoiding the locking of the vehicle and improving the braking performance of the vehicle.
For the convenience of understanding the present embodiment, first, a detailed description will be given of an anti-lock control method disclosed in the embodiments of the present application.
Fig. 1 is a flow chart illustrating an anti-lock control method according to an embodiment of the present invention. As shown in fig. 1, the method includes:
step 101, determining that the ABS is in a failure mode but the communication with the ABS is normal, and acquiring the wheel speed of a wheel;
in the embodiment of the invention, the ABS informs the electronic booster after determining that the ABS is in the failure mode. After learning that the ABS is in a fault mode, the electronic booster sends a heartbeat signal to detect the communication connection with the ABS and normally communicates with the ABS according to whether the communication connection can be detected, so that a corresponding braking control measure can be taken conveniently.
In the embodiment of the present invention, as an optional embodiment, the ABS communicates with a wheel speed sensor installed inside a wheel, and the wheel speed sensor starts to collect wheel speed from the moment when the vehicle is powered on, acquires wheel speed, and uploads the acquired wheel speed to the ABS. When the ABS is in a fault mode but the communication with the ABS is normal, the ABS transmits the received wheel speed to the electronic booster, and the electronic booster processes the wheel speed. Of course, in practical applications, the ABS may also process the wheel speed, and then transmit the processing result to the electronic booster, which is not limited in the embodiment of the present invention.
In an embodiment of the present invention, as an alternative embodiment, the wheel speed includes: left front wheel speed, left rear wheel speed, right front wheel speed, and right rear wheel speed.
In the embodiment of the invention, the wheel speed and the pedal displacement may be obtained according to a set time period during the running of the vehicle.
In this embodiment of the present invention, as an optional embodiment, the method further includes:
a11, determining that the ABS is in a non-failure mode, and controlling according to a preset mapping relation between pedal displacement and motor target displacement;
a12, recording the motor current and pedal displacement at the beginning of each ABS;
in the embodiment of the invention, when the ABS is in the failure mode and the ABS and the electronic booster cannot normally communicate with each other, the electronic booster cannot acquire the related braking information reported to the ABS, for example, the wheel speed, and therefore, the electronic booster cannot perform the braking process according to the braking information such as the wheel speed. In the embodiment of the invention, some auxiliary braking information which can be collected by the electronic booster is predetermined, so that the braking threshold value when the ABS is in the fault mode and can not normally communicate with the electronic booster is determined according to the auxiliary braking information, and corresponding braking processing can be carried out according to the determined braking threshold value. As an alternative embodiment, the auxiliary braking information includes: motor current and pedal displacement.
In the embodiment of the invention, when the ABS is in a non-failure mode, the electronic booster acquires the motor current and the pedal displacement from the pedal displacement sensor every time the ABS is triggered.
And A13, carrying out mean value processing on the recorded motor current to obtain and store a motor current threshold, and carrying out mean value processing on the recorded pedal displacement to obtain and store a pedal displacement threshold.
In the embodiment of the invention, the recorded motor current at the beginning of each ABS is averaged to obtain the motor current threshold, so that the calculated motor current threshold can be more accurate by counting the motor current at the beginning of the ABS for many times. Of course, in practical applications, other methods may also be used to process the motor current to obtain the motor current threshold, for example, fitting processing and the like, which is not limited in the embodiment of the present invention.
In the embodiment of the invention, the motor current threshold is calculated by using the following formula:
Figure BDA0002391803900000101
in the formula (I), the compound is shown in the specification,
current _ th is a motor current threshold;
current _ i is the motor current at the beginning of the ith ABS;
n is the number of ABS events.
In an embodiment of the present invention, the pedal displacement threshold is calculated using the following equation:
Figure BDA0002391803900000102
in the formula (I), the compound is shown in the specification,
PTS _ th is a pedal displacement threshold;
PTS _ i is the pedal displacement at the ith ABS start.
In this embodiment, as another optional embodiment, the method further includes:
a21, determining that the ABS is in a fault mode and the communication with the ABS is abnormal, and acquiring motor current and pedal displacement;
a22, if the acquired motor current is larger than the stored motor current threshold value, or the acquired pedal displacement is larger than the stored pedal displacement threshold value, controlling the motor to keep the current displacement; otherwise, inquiring a preset mapping relation between the pedal displacement and the motor target displacement to obtain the motor target displacement mapped by the pedal displacement, and controlling the motor to operate to the obtained motor target displacement.
In the embodiment of the invention, when the acquired motor current is greater than the stored motor current threshold value or the pedal displacement is greater than the stored pedal displacement threshold value, the fact that the vehicle is about to enter the ABS is indicated, but the ABS has a fault and cannot communicate with the electronic booster, so that the electronic booster controls the motor to maintain the current displacement unchanged in order to avoid the locking and instability of the wheels.
And if the motor current is not greater than the stored motor current threshold value or the pedal displacement is not greater than the stored pedal displacement threshold value, the electronic booster enters a normal boosting mode, and boosting control is performed according to the mapping relation table.
102, respectively determining a nominal vehicle speed, a wheel deceleration, a wheel speed vector and a slip degree corresponding to the current braking cycle based on the acquired wheel speed;
in the embodiment of the invention, when the vehicle is braked in the running process, the wheel speed is smaller than the vehicle body speed (nominal vehicle speed) due to the wheel slip, and the maximum wheel speed in 4 wheels is taken as the nominal vehicle speed.
In the embodiment of the present invention, as an alternative embodiment, fig. 2 is a schematic flow chart of determining a nominal vehicle speed corresponding to a current braking cycle based on an obtained wheel speed according to the embodiment of the present invention.
As shown in fig. 2, the method includes:
step 201, determining a current braking cycle, if the current braking cycle is a first braking cycle from the beginning of braking to the time when wheels recover to the limit, executing step 202, otherwise, executing step 205;
step 202, obtaining the wheel braking initial wheel speed when ABS begins;
step 203, calculating a product of a preset first brake cycle deceleration and a control period corresponding to the first brake cycle, and a first difference value between the wheel braking initial wheel speed and the product;
step 204, extracting the larger of the obtained wheel speed and the first difference value to obtain a nominal vehicle speed corresponding to the first brake cycle;
in the embodiment of the invention, if the ABS starts braking, the brake cycle in which the ABS is located is the first brake cycle, and the subsequent brake cycle is determined according to the previously determined brake cycle, since the deceleration in the first brake cycle is unknown, and the deceleration in the subsequent brake cycle can be calculated according to the wheel speed of the previous brake cycle and used as a reference, the nominal vehicle speed calculation corresponding to the brake cycle is divided into the nominal vehicle speed calculation corresponding to the first brake cycle and the nominal vehicle speed calculation corresponding to the non-first brake cycle. As an alternative embodiment, the nominal vehicle speed for the first braking cycle is calculated using the following equation:
Vref1＝max(w-xx,Vref1-old-aT1)
in the formula (I), the compound is shown in the specification,
Vref1a nominal vehicle speed corresponding to the first braking cycle;
w-xxobtaining wheel speed;
Vref1-oldthe nominal speed at the last moment is the initial value of w0-xx: the initial wheel speed of the wheel brake;
a is a preset first braking cycle deceleration;
T1the control period corresponding to the first brake cycle.
In an embodiment of the present invention, xx ═ fl, fr, rl, rr, where fl is a front left wheel, fr is a rear left wheel, rl is a front right wheel, and rr is a rear right wheel, then the nominal vehicle speed calculation formula corresponding to the first brake cycle may be rewritten as:
Vref1＝max(w-fl,w0-fl-aT1,w-fr,w0-fr-aT1,w-rl,w0-rl-aT1,w-rr,w0-rr-aT1)
wherein the content of the first and second substances,
Vref1-fl＝max(w-fl,w0-fl-aT1)
Vref1-fr＝max(w-fr,w0-fr-aT1)
Vref1-fr＝max(w-rl,w0-rl-aT1)
Vref1-rr＝max(w-rr,w0-rr-aT1)
in the formula (I), the compound is shown in the specification,
w-flfor the left front wheel speed, w, of the acquired wheel speeds0-flBraking an initial wheel speed for a left front wheel among the initial wheel speeds;
w-frfor left rear wheel speed among the acquired wheel speeds, w0-frBraking an initial wheel speed for a left rear wheel of the initial wheel speeds;
w-rl is the right front wheel speed among the acquired wheel speeds, w0-rlBraking an initial wheel speed for a right front wheel of the initial wheel speeds;
w-rrfor the right rear wheel speed among the acquired wheel speeds, w0-rrBraking an initial wheel speed for a right rear wheel among the initial wheel speeds;
Vref1-fla nominal left front wheel speed corresponding to the first brake cycle;
Vref1-fra nominal left rear wheel speed corresponding to the first brake cycle;
Vref1-rlnominal speed of the right front wheel for the first brake cycle
Vref1-rrAnd the nominal vehicle speed of the right rear wheel corresponding to the first brake cycle.
Step 205, obtaining a wheel braking starting wheel speed when a last braking cycle starts and a wheel recovery wheel speed when the wheel braking starting wheel speed is recovered to the limit;
step 206, acquiring the cycle time from the beginning of the last braking cycle braking to the time of recovering to the limit;
step 207, calculating a wheel speed difference between the wheel recovery wheel speed and the wheel braking starting wheel speed, and a deceleration ratio of the wheel speed difference to the cycle time;
step 208, calculating a second product of the deceleration ratio and a control period corresponding to the current braking cycle, and a second difference value of the wheel recovery speed and the second product;
and 209, extracting the larger of the obtained wheel speed and the second difference value to obtain a nominal vehicle speed corresponding to the current braking cycle.
In an embodiment of the present invention, the deceleration ratio is calculated using the following equation:
Figure BDA0002391803900000131
in the formula (I), the compound is shown in the specification,
a1-xxis the deceleration ratio;
wsk-xxstarting wheel speed for wheel braking when the last braking cycle starts braking; for the case where the previous brake cycle is the first brake cycle, the wheel braking start wheel speed is equal to the wheel braking initial wheel speed.
wsj-xxRestoring the wheel speed for the wheel when the last braking cycle is restored to the limit;
tsj-xxthe time when the last braking cycle is recovered to the limit;
tsk-xxthe time at which the last braking cycle started.
Calculating a nominal vehicle speed corresponding to the current braking cycle using:
Vref2＝max(w-xx,Vref2-old-a1-xxT2)
in the formula (I), the compound is shown in the specification,
Vref2the nominal vehicle speed corresponding to the current braking cycle;
Vref2-oldthe nominal vehicle speed corresponding to the previous moment;
T2is the control period corresponding to the current brake cycle. Wherein, T1＝T2。
In the embodiment of the invention, the wheel braking initial wheel speed w is recorded in the first braking cycle when the ABS braking is started0-xx(xx ═ fl, fr, rl, rr) and the time t at which braking beginssj-xxIn the first brake cycle, the wheel speed is reduced by a preset first brake cycle deceleration a, after the wheel is judged to be recovered to the limit according to the wheel speed vector and the slip degree, the recovered wheel speed w of the wheel at the moment is recordedsj-xxAnd a recovery time tsj-xxCalculating to obtain a deceleration ratio according to the wheel braking initial wheel speed, the wheel recovery wheel speed, the time when braking starts and the recovery time, taking the calculated deceleration ratio as the reference of the deceleration of the next braking cycle to calculate the nominal vehicle speed corresponding to the next braking cycle, and repeating the steps until braking is finished. The wheel recovery to the limit is determined according to the wheel speed vector and the slip degree, and the detailed description is given later.
In this embodiment of the present invention, as an optional embodiment, determining a slip degree corresponding to a current braking cycle based on an obtained wheel speed includes:
and calculating the difference value between the nominal vehicle speed corresponding to the current braking cycle and the obtained wheel speed to obtain the slip degree corresponding to the current braking cycle.
In the embodiment of the invention, the slip degree slip _ xx is calculated by using the following formula:
slip_xx＝Vrefn-w_xx
in the formula (I), the compound is shown in the specification,
Vrefnnominal speed corresponding to the current braking cycle, equal to Vref1Or Vref2。
In the embodiment of the invention, the wheel speed is differentiated and then filtered, so that the wheel deceleration (a) corresponding to the current braking cycle can be obtainedccf_xx)。
In the embodiment of the present invention, the wheel speed vector (dir) is determined_xx) The default direction is downward (dir)_xx1), as an alternative embodiment, taking the first braking cycle as an example, at the beginning of braking, taking the initial wheel speed of wheel braking at the time of wheel braking as the basic wheel speed, if the continuous k wheel speeds are all smaller than the basic wheel speed, the wheel speed vector is confirmed to be downward, if the continuous k wheel speeds are all larger than the basic wheel speed, the wheel speed vector is confirmed to be upward, otherwise, the wheel speed vector is confirmed to be kept unchanged. After the wheel speed vector of one-wheel vehicle is judged, the wheel speed of the wheel at the time of the judgment of the wheel speed vector is used for updating the basic wheel speed, and the wheel speed vector of the next-wheel vehicle is judged. The value of k can be calibrated in the test of the vehicle.
And 103, determining the current state of the wheel according to the slip degree, the wheel speed vector and the wheel deceleration, calculating the final motor target displacement according to the determined current state of the wheel and the preset mapping relation between the pedal displacement and the motor target displacement, and controlling the motor to operate to the final motor target displacement.
In this embodiment of the present invention, as an optional embodiment, determining the current state of the wheel according to the slip degree, the wheel speed vector, and the wheel deceleration includes:
if the slip degree and the wheel deceleration meet a preset first condition, wherein the first condition is that the slip degree of any wheel is greater than a preset first slip degree threshold value, or the slip degree of any wheel is greater than a preset second slip degree threshold value and the wheel deceleration is less than a preset deceleration threshold value, determining that the wheel enters an unstable state, and marking the state to be 1, wherein the first slip degree threshold value is greater than the second slip degree threshold value;
and the motor target displacement mapped by the unstable state is equal to the difference value of the current displacement of the motor and the preset adjusting displacement.
In the embodiment of the invention, if the wheel is indicated to enter an unstable state, decompression (brake release) is required.
In the embodiment of the invention, the current state of the wheel is judged, and if:
slip_xx＞slip1_theither, or,
Figure BDA0002391803900000161
it is determined that the wheel enters an unstable state.
In the formula (I), the compound is shown in the specification,
slip_xxis the degree of wheel slippage;
slip1_tha first threshold value for slip degree;
slip2_tha second threshold value for slip degree;
accf_xxis the wheel deceleration;
accf_this the deceleration threshold.
In the embodiment of the invention, if the slip degree and the wheel deceleration satisfy the first condition, the wheel is determined to enter the unstable state, and the state flag (temp) is set to 1. In the embodiment of the present invention, the status flag is set to 1 in order to distinguish the first entry into the ABS cycle from the following cycles.
In the embodiment of the invention, the motor target displacement mapped by the unstable state is determined by the following formula:
ServoTravelt＝ServoTraveld-delts
in the formula (I), the compound is shown in the specification,
ServoTraveltthe target displacement of the motor is obtained;
ServoTraveldthe current displacement of the motor is obtained;
delts is the preset modulation shift.
In this embodiment, as another optional embodiment, the method further includes:
if the slip degree and the wheel deceleration do not meet the preset first condition, judging whether the wheel speed vectors and the preset state marks meet the preset second condition, and if so, determining that the wheels enter a stable state, wherein the second condition is that the wheel speed vectors of all the wheels are default upward wheel speed vectors and the state marks are set to be 1;
and the motor target displacement mapped by the stable state is equal to the current displacement of the motor.
In the embodiment of the present invention, the second condition is that the wheel speed vectors of all the wheels are preset wheel speed vectors and the state flag is set to 1, in the case that the first condition is not satisfied, if the second condition is satisfied, it is determined that all the wheels have entered a stable state, and in the stable state, pressure maintaining (current braking is maintained) is performed, and the target displacement of the motor is equal to the current displacement of the motor.
In the embodiment of the present invention, the second condition is:
Figure BDA0002391803900000171
wherein dir is the default upward wheel speed vector if the wheel speed vector is the default upward wheel speed vector_xx＝0。
In particular dir_xx0 is:
dir_fl＝0&&dir_fr＝0&&dir_rl＝0&&dir_rr＝0。
in this embodiment, as a further optional embodiment, the method further includes:
if the wheel speed vectors and the preset state marks do not meet the preset second condition, judging whether the slip degree, the wheel speed vectors and the preset state marks meet a preset third condition, and if so, determining that the wheels have recovered to the limit state, wherein the third condition is that the wheel speed vectors of all the wheels are default downward wheel speed vectors, the slip degree of all the wheels is smaller than a preset slip degree third threshold value and the state marks are set to be 1, wherein the slip degree third threshold value is smaller than a slip degree second threshold value;
and the motor target displacement mapped by the limit state is equal to the sum of the current displacement of the motor and the preset adjusting displacement.
In the embodiment of the present invention, the third condition is:
Figure BDA0002391803900000181
in the formula (I), the compound is shown in the specification,
slip3_this a third threshold for slip level.
In the embodiment of the invention, slip1_th＞slip2_th＞slip3_th。
In the embodiment of the invention, if the wheel speed vectors of all the wheels are not the preset wheel speed vectors, the state flag is set to 1, and the slip degrees are all smaller than the third threshold value of the slip degree, the wheels are restored to the limit and need to be boosted (enhanced for braking), and the target displacement of the motor is equal to the sum of the current displacement of the motor and the preset regulation displacement.
In this embodiment, as a further optional embodiment, the method further includes:
if the slip degree, the wheel speed vector and the preset state mark do not meet the preset third condition, determining that the wheel does not enter an ABS state, and setting the state mark to be 0;
acquiring current pedal displacement;
and the motor target displacement which does not enter the ABS state mapping refers to the preset mapping relation between the pedal displacement and the motor target displacement.
In the embodiment of the invention, the pedal displacement is acquired by using the pedal displacement sensor in the electronic booster.
In the embodiment of the invention, when the wheel does not enter the ABS state, the electronic booster is in the normal boosting stage, the motor target displacement mapped by the current pedal displacement is obtained by inquiring the mapping relation table of the motor target displacement and the pedal displacement, and the motor is controlled to operate to the obtained motor target displacement. The first threshold value of the slip degree, the second threshold value of the slip degree and the third threshold value of the slip degree can be calibrated in the test of the vehicle.
According to the anti-lock control method provided by the embodiment of the invention, the wheel speed of a wheel is obtained by determining that an anti-lock brake system ABS is in a failure mode but normal in communication with the ABS; respectively determining a nominal vehicle speed, a wheel deceleration, a wheel speed vector and a slip degree corresponding to the current braking cycle based on the acquired wheel speed; and determining the current state of the wheel according to the slip degree, the wheel speed vector and the wheel deceleration, calculating the final motor target displacement according to the determined current state of the wheel and the preset mapping relation between the pedal displacement and the motor target displacement, and controlling the motor to operate to the final motor target displacement. Like this, but with electronic booster communication normal condition under the ABS trouble, confirm the wheel state through the wheel speed, according to the judgement to the wheel state, utilize electronic booster to carry out the target displacement control of motor of corresponding state to control wheel pressure because the wheel speed can react the actual braking operating mode, make braking control identical with the actual braking operating mode, thereby can effectively guarantee that the wheel does not lock, effectively promoted the brake performance of vehicle. Further, when the ABS has no fault and the target displacement of the motor is controlled according to the original anti-lock control program, the corresponding motor current threshold value and the pedal displacement threshold value are determined and stored by recording the motor current and the pedal displacement when the ABS starts, so that when the ABS is in a fault mode and cannot normally communicate with the electronic booster, the corresponding braking processing can be carried out according to the stored motor current threshold value and the stored pedal displacement threshold value.
And the pressure of the wheel is adjusted by utilizing the electronic booster based on different control modes corresponding to different motor target displacements. Therefore, the locking of the wheels can be prevented in the ABS working process, and certain assistance is ensured in the normal braking stage.
Fig. 3 is a schematic flow chart illustrating a specific anti-lock control method according to an embodiment of the present invention. As shown in fig. 3, the method includes:
step 301, judging whether the ABS is in fault, if so, executing step 302, otherwise, executing step 321;
step 321, receiving a control instruction sent by the ABS according to a preset anti-lock control program, and performing electronic power-assisted control according to the control instruction;
step 322, recording the motor current and pedal displacement at the beginning of each ABS;
step 323, carrying out mean value processing on the recorded motor current to obtain and store a motor current threshold value, and carrying out mean value processing on the recorded pedal displacement to obtain and store a pedal displacement threshold value;
step 302, judging whether the communication with the ABS is normal or not, if so, executing step 303, otherwise, executing step 315;
315, obtaining the current of the motor and the displacement of the pedal;
step 316, judging whether the acquired motor current is greater than a stored motor current threshold or not, or whether the pedal displacement is greater than a stored pedal displacement threshold or not, if so, executing step 317, otherwise, executing step 318;
step 317, controlling the motor to keep the current displacement;
in the embodiment of the invention, when the acquired motor current is greater than the stored motor current threshold value or the pedal displacement is greater than the stored pedal displacement threshold value, the fact that the vehicle is about to enter the ABS is indicated, but the ABS has a fault and cannot communicate with the electronic booster, so that the electronic booster controls the motor to maintain the current displacement unchanged in order to avoid the locking and instability of the wheels.
Step 318, inquiring a preset mapping relation between the pedal displacement and the motor target displacement to obtain the motor target displacement mapped by the pedal displacement;
in the embodiment of the invention, if the motor current is not greater than the stored motor current threshold value or the pedal displacement is not greater than the stored pedal displacement threshold value, the electronic booster enters a normal boosting mode and performs boosting control according to the mapping relation table.
Step 319, controlling the motor to operate until the obtained motor target displacement is obtained;
step 303, obtaining the wheel speed;
in the embodiment of the present invention, before the wheel speed is obtained, the status flag may be determined to be set to 0.
Step 304, calculating a nominal vehicle speed, a wheel deceleration, a wheel speed vector and a slip degree according to the wheel speed;
step 305, judging whether the slip degree and the wheel deceleration meet a first condition, if so, executing step 306, otherwise, executing step 307;
step 306, setting the state flag to be 1, and controlling the target displacement of the motor to be equal to the difference value between the current displacement of the motor and the preset adjusting displacement;
in the embodiment of the invention, if the first condition is met, indicating that the wheel enters an unstable state, decompression is required.
Step 307, judging whether the wheel speed vector and the preset state mark meet a second condition, if so, executing step 308, otherwise, executing step 309;
308, controlling the target displacement of the motor to be equal to the current displacement of the motor;
in the embodiment of the invention, if the first condition is not met but the second condition is met, the wheel enters a stable state, and pressure maintaining is required.
Step 309, judging whether the slippage degree, the wheel speed vector and the preset state mark meet a third condition, if so, executing step 310, otherwise, executing step 311;
step 310, controlling the target displacement of the motor to be equal to the sum of the current displacement of the motor and a preset adjusting displacement;
in the embodiment of the invention, if the first condition and the second condition are not met but the third condition is met, the wheel is recovered to the limit, and pressurization is required.
Step 311, acquiring the current pedal displacement;
step 312, inquiring a preset mapping relationship between pedal displacement and motor target displacement to obtain a motor target displacement mapped by the current pedal displacement;
and 313, controlling the motor target displacement to be equal to the obtained motor target displacement.
In the embodiment of the invention, if the first condition, the second condition and the third condition are not met, the wheel does not enter an ABS state, and the electronic booster works according to the current normal boosting mode.
In the embodiment of the invention, according to the ABS fault and the communication condition of the ABS and the electronic booster, the brake control is divided into three types, the wheel pressure is adjusted by using the electronic booster based on the target displacement of the motor corresponding to different brake controls, so that the wheel locking can be prevented in the ABS working process, and a certain boosting force is ensured in the normal braking stage: the first is that the ABS is in a non-failure mode, the second is that the ABS is in a failure mode and the communication between the ABS and the electronic booster is abnormal, and the third is that the ABS is in a failure mode and the communication between the ABS and the electronic booster is normal. For the first brake control, controlling according to the existing anti-lock control program, and acquiring and storing a motor current threshold and a pedal displacement threshold; for the second type of brake control, the target displacement of the motor is controlled according to the current motor current and pedal displacement as well as the stored motor current threshold and pedal displacement threshold; and for the third brake control, determining the current state of the wheel according to the acquired wheel speed, and controlling the target displacement of the motor according to the current state of the wheel.
Fig. 4 is a schematic structural diagram of an anti-lock control device according to an embodiment of the present invention. As shown in fig. 4, includes:
a wheel speed obtaining module 401, configured to determine that an ABS is in a failure mode but communication with the ABS is normal, and obtain a wheel speed;
in the embodiment of the invention, the wheel speed is acquired by using the wheel speed sensor which is arranged in the wheel and is communicated with the ABS.
In an embodiment of the present invention, the wheel speed includes: left front wheel speed, left rear wheel speed, right front wheel speed, and right rear wheel speed.
A calculating module 402, configured to determine, based on the obtained wheel speed, a nominal vehicle speed, a wheel deceleration, a wheel speed vector, and a slip degree corresponding to a current braking cycle, respectively;
in the embodiment of the invention, when the vehicle is braked in the running process, the wheel speed is smaller than the vehicle body speed (nominal vehicle speed) due to the wheel slip, and the maximum wheel speed in 4 wheels is taken as the nominal vehicle speed.
In this embodiment, as an alternative embodiment, the calculating module 402 comprises a nominal vehicle speed calculating unit (not shown), wherein,
the nominal vehicle speed calculating unit is used for determining the current braking cycle, and if the current braking cycle is the first braking cycle from the beginning of braking to the time when the wheels recover to the limit; acquiring the initial wheel speed of wheel braking when ABS begins; calculating a product of a preset first brake cycle deceleration and a control period corresponding to the first brake cycle, and a first difference value between the wheel braking initial wheel speed and the product; and extracting the larger of the obtained wheel speed and the first difference value to obtain a nominal vehicle speed corresponding to the first brake cycle.
In this embodiment of the present invention, as an optional embodiment, the nominal vehicle speed calculating unit is further configured to:
if the current braking cycle is not the first braking cycle;
obtaining the wheel braking starting wheel speed when the last braking cycle starts and the wheel recovery wheel speed when the limit is recovered;
acquiring the cycle time from the beginning of the last braking cycle to the time of recovering to the limit;
calculating a wheel speed difference between the wheel recovery wheel speed and a wheel braking start wheel speed, and calculating a deceleration ratio of the wheel speed difference to the cycle time;
calculating a second product of the deceleration ratio and a control period corresponding to the current braking cycle, and a second difference value of the wheel recovery wheel speed and the second product;
and extracting the larger of the obtained wheel speed and the second difference value to obtain the nominal vehicle speed corresponding to the current braking cycle.
In this embodiment of the present invention, as another optional embodiment, the calculating module 402 further includes:
and the slip degree calculating unit is used for calculating the difference value between the nominal vehicle speed corresponding to the current braking cycle and the obtained wheel speed to obtain the slip degree corresponding to the current braking cycle.
In this embodiment of the present invention, as yet another optional embodiment, the calculating module 402 further includes:
and the wheel deceleration calculating unit is used for differentiating the wheel speed and then filtering to obtain the wheel deceleration corresponding to the current braking cycle.
And a motor displacement control module 403, configured to determine a current state of the wheel according to the slip degree, the wheel speed vector, and the wheel deceleration, calculate a final motor target displacement according to the determined current state of the wheel and a preset mapping relationship between pedal displacement and motor target displacement, and control the motor to operate to the final motor target displacement.
In the embodiment of the present invention, as an optional embodiment, the motor displacement control module 403 is specifically configured to:
if the slip degree and the wheel deceleration meet a preset first condition, wherein the first condition is that the slip degree of any wheel is greater than a preset first slip degree threshold value, or the slip degree of any wheel is greater than a preset second slip degree threshold value and the wheel deceleration is less than a preset deceleration threshold value, determining that the wheel enters an unstable state, and marking the state to be 1, wherein the first slip degree threshold value is greater than the second slip degree threshold value;
and the motor target displacement mapped by the unstable state is equal to the difference value of the current displacement of the motor and the preset adjusting displacement.
In this embodiment of the present invention, as another optional embodiment, the motor displacement control module 403 is further configured to:
if the slip degree and the wheel deceleration do not meet the preset first condition, judging whether the wheel speed vectors and the preset state marks meet the preset second condition, and if so, determining that the wheels enter a stable state, wherein the second condition is that the wheel speed vectors of all the wheels are default upward wheel speed vectors and the state marks are set to be 1;
and the motor target displacement mapped by the stable state is equal to the current displacement of the motor.
In this embodiment of the present invention, as a further optional embodiment, the motor displacement control module 403 is further configured to:
if the wheel speed vectors and the preset state marks do not meet the preset second condition, judging whether the slip degree, the wheel speed vectors and the preset state marks meet a preset third condition, and if so, determining that the wheels are all restored to the limit state, wherein the third condition is that the wheel speed vectors of all the wheels are default downward wheel speed vectors, the slip degree of all the wheels is smaller than a preset slip degree third threshold value and the state marks are set to be 1, and the slip degree third threshold value is smaller than a slip degree second threshold value;
and the motor target displacement mapped by the limit state is equal to the sum of the current displacement of the motor and the preset adjusting displacement.
In this embodiment of the present invention, as a further optional embodiment, the motor displacement control module 403 is further configured to:
if the slip degree, the wheel speed vector and the preset state mark do not meet the preset third condition, determining that the wheel does not enter an ABS state, and setting the state mark to be 0;
acquiring current pedal displacement;
and the motor target displacement which does not enter the ABS state mapping refers to the preset mapping relation between the pedal displacement and the motor target displacement.
In this embodiment of the present invention, as an optional embodiment, the control device further includes:
a non-failure processing module (not shown in the figure) for determining that the ABS is in a non-failure mode, and controlling according to a preset mapping relationship between pedal displacement and motor target displacement; recording the motor current and pedal displacement at the beginning of each ABS; and carrying out mean value processing on the recorded motor current to obtain and store a motor current threshold value, and carrying out mean value processing on the recorded pedal displacement to obtain and store a pedal displacement threshold value.
In this embodiment, as another optional embodiment, the control device further includes:
the communication abnormity processing module is used for determining that the ABS is in a fault mode and has abnormal communication with the ABS, and acquiring motor current and pedal displacement; if the obtained motor current is larger than the stored motor current threshold value, or the obtained pedal displacement is larger than the stored pedal displacement threshold value, controlling the motor to keep the current displacement; otherwise, inquiring a preset mapping relation between the pedal displacement and the motor target displacement to obtain the motor target displacement mapped by the pedal displacement, and controlling the motor to operate to the obtained motor target displacement.
As shown in fig. 5, an embodiment of the present application provides a computer device 500 for executing the anti-lock control method in fig. 1 to 3, the device includes a memory 501, a processor 502, and a computer program stored on the memory 501 and executable on the processor 502, wherein the processor 502 implements the steps of the anti-lock control method when executing the computer program.
Specifically, the memory 501 and the processor 502 can be general-purpose memory and processor, and are not limited to this, and when the processor 502 executes the computer program stored in the memory 501, the anti-lock control method can be executed.
Corresponding to the anti-lock control method in fig. 1, the present application further provides a computer readable storage medium having a computer program stored thereon, where the computer program is executed by a processor to execute the steps of the anti-lock control method.
Specifically, the storage medium can be a general-purpose storage medium, such as a removable disk, a hard disk, or the like, and when executed, the computer program on the storage medium can execute the above anti-lock control method.
In the embodiments provided in the present application, it should be understood that the disclosed system and method may be implemented in other ways. The above-described system embodiments are merely illustrative, and for example, the division of the units is only one logical functional division, and there may be other divisions in actual implementation, and for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection of systems or units through some communication interfaces, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments provided in the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.
The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus once an item is defined in one figure, it need not be further defined and explained in subsequent figures, and moreover, the terms "first", "second", "third", etc. are used merely to distinguish one description from another and are not to be construed as indicating or implying relative importance.
Finally, it should be noted that: the above-mentioned embodiments are only specific embodiments of the present application, and are used for illustrating the technical solutions of the present application, but not limiting the same, and the scope of the present application is not limited thereto, and although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: any person skilled in the art can modify or easily conceive the technical solutions described in the foregoing embodiments or equivalent substitutes for some technical features within the technical scope disclosed in the present application; such modifications, changes or substitutions do not depart from the spirit and scope of the present disclosure, which should be construed in light of the above teachings. Are intended to be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (12)

1. An anti-lock control method, characterized by comprising:
determining that an anti-lock brake system (ABS) is in a failure mode but the communication with the ABS is normal, and acquiring the wheel speed of a wheel;
respectively determining a nominal vehicle speed, a wheel deceleration, a wheel speed vector and a slip degree corresponding to the current braking cycle based on the acquired wheel speed;
and determining the current state of the wheel according to the slip degree, the wheel speed vector and the wheel deceleration, calculating the final motor target displacement according to the determined current state of the wheel and the preset mapping relation between the pedal displacement and the motor target displacement, and controlling the motor to operate to the final motor target displacement.
2. The control method according to claim 1, characterized in that the method further comprises:
determining that the ABS is in a non-failure mode, and controlling according to a preset mapping relation between pedal displacement and motor target displacement;
recording the motor current and pedal displacement at the beginning of each ABS;
and carrying out mean value processing on the recorded motor current to obtain and store a motor current threshold value, and carrying out mean value processing on the recorded pedal displacement to obtain and store a pedal displacement threshold value.
3. The control method according to claim 1, characterized in that the method further comprises:
determining that the ABS is in a fault mode and the communication between the ABS and the ABS is abnormal, and acquiring motor current and pedal displacement;
if the obtained motor current is larger than the stored motor current threshold value, or the obtained pedal displacement is larger than the stored pedal displacement threshold value, controlling the motor to keep the current displacement; otherwise, inquiring a preset mapping relation between the pedal displacement and the motor target displacement to obtain the motor target displacement mapped by the pedal displacement, and controlling the motor to operate to the obtained motor target displacement.
4. The control method of claim 1, wherein said determining a nominal vehicle speed for the current braking cycle comprises:
determining the current braking cycle, and if the current braking cycle is the first braking cycle from the beginning of braking to the time when the wheels recover to the limit;
acquiring the initial wheel speed of wheel braking when ABS begins;
calculating a product of a preset first brake cycle deceleration and a control period corresponding to the first brake cycle, and a first difference value between the wheel braking initial wheel speed and the product;
and extracting the larger of the obtained wheel speed and the first difference value to obtain a nominal vehicle speed corresponding to the first brake cycle.
5. The control method according to claim 4, characterized in that the method further comprises:
if the current braking cycle is not the first braking cycle;
obtaining the wheel braking starting wheel speed when the last braking cycle starts and the wheel recovery wheel speed when the limit is recovered;
acquiring the cycle time from the beginning of the last braking cycle to the time of recovering to the limit;
calculating a wheel speed difference between the wheel recovery wheel speed and a wheel braking start wheel speed, and calculating a deceleration ratio of the wheel speed difference to the cycle time;
calculating a second product of the deceleration ratio and a control period corresponding to the current braking cycle, and a second difference value of the wheel recovery wheel speed and the second product;
and extracting the larger of the obtained wheel speed and the second difference value to obtain the nominal vehicle speed corresponding to the current braking cycle.
6. The control method according to claim 1, 4 or 5, wherein determining the current state of the wheel based on the slip degree, the wheel speed vector, and the wheel deceleration comprises:
if the slip degree and the wheel deceleration meet a preset first condition, wherein the first condition is that the slip degree of any wheel is greater than a preset first slip degree threshold value, or the slip degree of any wheel is greater than a preset second slip degree threshold value and the wheel deceleration is less than a preset deceleration threshold value, determining that the wheel enters an unstable state, and marking the state to be 1, wherein the first slip degree threshold value is greater than the second slip degree threshold value;
and the motor target displacement mapped by the unstable state is equal to the difference value of the current displacement of the motor and the preset adjusting displacement.
7. The control method according to claim 6, characterized in that the method further comprises:
if the slip degree and the wheel deceleration do not meet the preset first condition, judging whether the wheel speed vectors and the preset state marks meet the preset second condition, and if so, determining that the wheels enter a stable state, wherein the second condition is that the wheel speed vectors of all the wheels are default upward wheel speed vectors and the state marks are set to be 1;
and the motor target displacement mapped by the stable state is equal to the current displacement of the motor.
8. The control method according to claim 7, characterized in that the method further comprises:
if the wheel speed vectors and the preset state marks do not meet the preset second condition, judging whether the slip degree, the wheel speed vectors and the preset state marks meet a preset third condition, and if so, determining that the wheels are all restored to the limit state, wherein the third condition is that the wheel speed vectors of all the wheels are default downward wheel speed vectors, the slip degree of all the wheels is smaller than a preset slip degree third threshold value and the state marks are set to be 1, and the slip degree third threshold value is smaller than a slip degree second threshold value;
and the motor target displacement mapped by the limit state is equal to the sum of the current displacement of the motor and the preset adjusting displacement.
9. The control method according to claim 8, characterized in that the method further comprises:
if the slip degree, the wheel speed vector and the preset state mark do not meet the preset third condition, determining that the wheel does not enter an ABS state, and setting the state mark to be 0;
acquiring current pedal displacement;
and the motor target displacement which does not enter the ABS state mapping refers to the preset mapping relation between the pedal displacement and the motor target displacement.
10. An anti-lock control device, characterized by comprising:
the wheel speed acquisition module is used for determining that an anti-lock braking system ABS is in a failure mode but the communication with the ABS is normal and acquiring the wheel speed;
the calculation module is used for respectively determining a nominal vehicle speed, a wheel deceleration, a wheel speed vector and a slip degree corresponding to the current braking cycle based on the acquired wheel speed;
and the motor displacement control module is used for determining the current state of the wheel according to the slip degree, the wheel speed vector and the wheel deceleration, calculating the final motor target displacement according to the determined current state of the wheel and the preset mapping relation between the pedal displacement and the motor target displacement, and controlling the motor to operate to the final motor target displacement.
11. An electronic device, comprising: a processor, a memory and a bus, the memory storing machine-readable instructions executable by the processor, the processor and the memory communicating via the bus when the electronic device is operating, the machine-readable instructions when executed by the processor performing the steps of the anti-lock control method according to any one of claims 1 to 9.
12. A computer-readable storage medium, having stored thereon a computer program for executing the steps of the anti-lock control method according to any one of claims 1 to 9 when executed by a processor.
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