CN111959469A - Wheel anti-lock control method and device and vehicle - Google Patents
Wheel anti-lock control method and device and vehicle Download PDFInfo
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- CN111959469A CN111959469A CN202010852202.4A CN202010852202A CN111959469A CN 111959469 A CN111959469 A CN 111959469A CN 202010852202 A CN202010852202 A CN 202010852202A CN 111959469 A CN111959469 A CN 111959469A
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- wheel
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- braking force
- slip ratio
- wheel slip
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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
- B60T8/1761—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS responsive to wheel or brake dynamics, e.g. wheel slip, wheel acceleration or rate of change of brake fluid pressure
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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
Abstract
The invention discloses a wheel anti-lock control method provided by an embodiment, which comprises the steps of firstly, obtaining the wheel slip rate of each wheel; and adjusting the target master cylinder pressure according to the wheel slip rate of each wheel until the wheel slip rate of each wheel is between a first threshold value and a second threshold value, wherein the first threshold value is smaller than the second threshold value, so that the electronic power-assisted brake system still has the functions of wheel anti-lock and brake force adjustment after the whole vehicle stability system (ABS or ESC) fails, and the active safety performance of the vehicle is improved. The invention also discloses a wheel anti-lock control device and a vehicle.
Description
Technical Field
The embodiment of the invention relates to the technical field of vehicles, in particular to a wheel anti-lock control method, a wheel anti-lock control device and a vehicle.
Background
Along with the high-speed development of the automobile industry, the degree of electronic integration and intellectualization of automobiles is higher and higher, wherein the brake-by-wire is particularly outstanding, and the highly integrated brake-by-wire service brake can reduce the energy consumption of the automobiles to the greatest extent and has higher brake performance. The Electronic power-assisted brake System is an Electronic linear control System developed based on a conventional vacuum booster, and has the advantages that the braking force or deceleration expected by a driver can be achieved without being influenced by a vacuum source, but after an ABS (Anti-lock braking System) or an ESC (Electronic stability Controller) fails, if wheels are locked during braking, the lateral disturbance outside the vehicle can cause the tail flicking, thereby causing serious traffic accidents.
Disclosure of Invention
The invention provides a wheel anti-lock control method, a device and a vehicle, which are used for realizing that an electronic power-assisted brake system still has the functions of wheel anti-lock and braking force regulation after an entire vehicle stability system (ABS or ESC) fails so as to improve the active safety performance of the vehicle.
In order to achieve the above object, an embodiment of an aspect of the present invention provides a wheel anti-lock control method, including:
obtaining the wheel slip rate of each wheel;
and adjusting the target master cylinder pressure according to the wheel slip ratio of each wheel until the wheel slip ratio of each wheel is between a first threshold value and a second threshold value, wherein the first threshold value is smaller than the second threshold value.
Optionally, the adjusting the target master cylinder pressure according to the magnitude of the wheel slip ratio of each wheel until the wheel slip ratio of each wheel is between a first threshold value and a second threshold value includes:
if the wheel slip ratio of one wheel is larger than or equal to a third threshold value, acquiring target braking force corresponding to the current wheel slip ratio of each wheel, and selecting the minimum target braking force as a first target master cylinder pressure until the wheel slip ratio of each wheel is smaller than the third threshold value;
if the wheel slip ratio of one wheel is larger than or equal to a second threshold value, acquiring target braking force corresponding to the current wheel slip ratio of each wheel, and selecting the minimum target braking force as a second target master cylinder pressure until the wheel slip ratio of each wheel is smaller than the second threshold value;
if the wheel slip ratio of one wheel is smaller than a first threshold value, acquiring target braking force corresponding to the current wheel slip ratio of each wheel, selecting the minimum target braking force as third target master cylinder pressure, and increasing the third target master cylinder pressure by a preset value as fourth target master cylinder pressure until the wheel slip ratio of each wheel is larger than or equal to the first threshold value; wherein the third threshold is greater than the second threshold, and the second threshold is greater than the first threshold.
Optionally, before the obtaining the wheel slip ratio of each wheel, the method further includes:
judging whether the expected braking force of a driver is larger than a braking force threshold value, wherein the braking force threshold value is a braking force value for triggering ABS or ESC;
if the expected braking force of the driver is larger than the braking force threshold value, judging whether the vehicle state is in a dynamic state;
and if the vehicle is in a dynamic state, acquiring the wheel slip rate of each wheel.
Optionally, before the determining whether the driver's desired braking force is greater than the braking force threshold value, the method further includes:
acquiring the opening degree of a brake pedal;
if the opening degree of the brake pedal is larger than or equal to a fourth threshold value, acquiring the expected braking force of the driver; and judging whether the expected braking force of the driver is larger than the braking force threshold value or not.
Optionally, the determining whether the vehicle state is in a dynamic state includes:
and acquiring a first wheel speed of the wheel, calculating the vehicle speed according to the first wheel speed of the wheel, and if the vehicle speed is greater than a fifth threshold value, keeping the vehicle state in a dynamic state.
Optionally, the determining whether the vehicle state is in a dynamic state includes:
and obtaining wheel speed pulses of wheels, calculating second wheel speeds of the wheels according to the wheel speed pulses of the wheels, calculating vehicle speed according to the second wheel speeds of the wheels, and if the vehicle speed is greater than a fifth threshold value, enabling the vehicle state to be in a dynamic state.
Optionally, before acquiring the vehicle speed, the method further includes:
and calculating the difference value between the first wheel speed and the second wheel speed, and if the difference value is smaller than a seventh threshold value, acquiring the vehicle speed.
In order to achieve the above object, a second aspect of the present invention provides a wheel anti-lock control device, including:
the wheel slip rate acquisition module is used for acquiring the wheel slip rate of each wheel;
and the target master cylinder pressure adjusting module is used for adjusting the target master cylinder pressure according to the wheel slip ratio of each wheel until the wheel slip ratio of each wheel is between a first threshold value and a second threshold value, wherein the first threshold value is smaller than the second threshold value.
Optionally, the target master cylinder pressure adjustment module includes:
the first adjusting module is used for acquiring target braking force corresponding to the current wheel slip rate of each wheel if the wheel slip rate of one wheel is larger than or equal to a third threshold value, and selecting the minimum target braking force as a first target master cylinder pressure until the wheel slip rate of each wheel is smaller than the third threshold value;
the second adjusting module is used for acquiring target braking force corresponding to the current wheel slip rate of each wheel if the wheel slip rate of one wheel is larger than or equal to a second threshold value, and selecting the minimum target braking force as a second target master cylinder pressure until the wheel slip rate of each wheel is smaller than the second threshold value;
the third adjusting module is used for acquiring target braking force corresponding to the current wheel slip rate of each wheel if the wheel slip rate of one wheel is smaller than a first threshold value, selecting the minimum target braking force as third target master cylinder pressure, and increasing the third target master cylinder pressure by a preset value as fourth target master cylinder pressure until the wheel slip rate of each wheel is larger than or equal to the first threshold value; wherein the third threshold is greater than the second threshold, and the second threshold is greater than the first threshold.
Optionally, the wheel anti-lock control device further includes:
the braking force threshold value is a braking force value for triggering the ABS or the ESC;
the second judgment module is used for judging whether the vehicle state is in a dynamic state or not if the expected braking force of the driver is larger than the braking force threshold value;
and if the vehicle is in a dynamic state, acquiring the wheel slip rate of each wheel.
Optionally, the wheel anti-lock control device further includes:
the brake pedal opening obtaining module is used for obtaining the opening of a brake pedal;
the third judgment module is used for acquiring the expected braking force of the driver if the opening degree of the brake pedal is greater than or equal to a fourth threshold value; and judging whether the expected braking force of the driver is larger than the braking force threshold value or not.
Optionally, the wheel anti-lock control device includes:
the first wheel speed acquisition module is used for acquiring a first wheel speed of a wheel;
the vehicle speed acquisition module is used for calculating the vehicle speed according to the first wheel speed of the wheel;
and the fourth judgment module is used for judging that the vehicle state is in a dynamic state if the vehicle speed is greater than a fifth threshold value.
Optionally, the wheel anti-lock control device includes:
the second wheel speed acquisition module is used for acquiring wheel speed pulses of the wheels and calculating second wheel speeds of the wheels according to the wheel speed pulses of the wheels;
the vehicle speed obtaining module is used for calculating the vehicle speed according to the second wheel speed of the wheel, and if the vehicle speed is larger than a fifth threshold value, the vehicle state is in a dynamic state.
Optionally, the wheel anti-lock control device further includes:
a calculation module for calculating a difference between the first wheel speed and the second wheel speed;
and the sixth judgment module is used for acquiring the vehicle speed if the difference value is smaller than a seventh threshold value.
In order to achieve the above object, a vehicle according to a third aspect of the present invention includes the wheel anti-lock control device.
According to the wheel anti-lock control method, the wheel anti-lock control device and the vehicle provided by the embodiment of the invention, firstly, the wheel slip rate of each wheel is obtained; and adjusting the target master cylinder pressure according to the wheel slip rate of each wheel until the wheel slip rate of each wheel is between a first threshold value and a second threshold value, wherein the first threshold value is smaller than the second threshold value, so that the electronic power-assisted brake system still has the functions of wheel anti-lock and brake force adjustment after the whole vehicle stability system (ABS or ESC) fails, and the active safety performance of the vehicle is improved.
Drawings
FIG. 1 is a schematic structural diagram of a decoupled electric power-assisted brake system of the prior art;
FIG. 2 is a flowchart of a wheel anti-lock control method according to an embodiment of the present invention;
FIG. 3 is a flow chart of a method of anti-lock control of wheels according to one embodiment of the present invention;
FIG. 4 is a flowchart of a wheel anti-lock control method according to another embodiment of the present invention;
FIG. 5 is a flowchart of a wheel anti-lock control method according to yet another embodiment of the present invention;
FIG. 6 is a flowchart of a wheel anti-lock control method according to still another embodiment of the present invention;
FIG. 7 is a flowchart of a wheel anti-lock control method according to still another embodiment of the present invention;
FIG. 8 is a flowchart of a wheel anti-lock control method according to still another embodiment of the present invention;
FIG. 9 is a flowchart of a wheel anti-lock control method according to still another embodiment of the present invention;
fig. 10 is a block diagram of a wheel anti-lock control device according to an embodiment of the present invention;
fig. 11 is a block diagram of a wheel anti-lock control device according to an embodiment of the present invention;
fig. 12 is a block diagram of an anti-lock control device for wheels according to another embodiment of the present invention;
fig. 13 is a block diagram of a wheel anti-lock control device according to still another embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Fig. 1 is a schematic structural diagram of a decoupling type electric power-assisted brake system in the prior art. As shown in fig. 1, the decoupled electronic power-assisted brake system comprises an electronic control unit 1, a motor 2, a motor bearing 3, a rack 4, a hydraulic piston 5, brake fluid 6, a brake master cylinder 7, a brake pedal 8 and a pedal stroke sensor 9. The pedal stroke sensor 9 collects the stroke of a pedal push rod of the brake pedal 8 in real time and sends the stroke to the electronic control unit 1, the electronic control unit 1 converts the stroke of the pedal push rod into the boosting output power of the motor 2, the motor 2 is controlled to drive the motor bearing 3 to rotate according to the boosting output power, the rack 4 is driven, the hydraulic piston 5 is driven to push the brake fluid 6, and therefore the brake master cylinder 7 outputs the brake fluid to generate brake force. It should be noted that, a gap is left between the pedal push rod (not shown in the figure) and the rack 4, so that decoupling can be realized, and the pedal feeling of the driver is not obviously changed when the brake system adjusts the braking force, as described in the patent application No. 201910843791.7.
Fig. 2 is a flowchart of a wheel anti-lock control method according to an embodiment of the present invention. As shown in fig. 2, the wheel anti-lock control method includes the steps of:
s101, obtaining the wheel slip rate of each wheel;
wherein, the formula for calculating the wheel slip rate is
v is the running speed of the vehicle, ω is the angular velocity of the wheel, and r is the rolling radius of the wheel, wherein v can be calculated and obtained according to the wheel speed obtained by the wheel speed sensor, ω can be obtained according to the angular velocity sensor, and r can be calibrated in advance when the vehicle leaves a factory, so that the wheel slip ratio of each wheel can be obtained according to the values.
S102, adjusting the target master cylinder pressure according to the wheel slip ratio of each wheel until the wheel slip ratio of each wheel is between a first threshold value and a second threshold value, wherein the first threshold value is smaller than the second threshold value.
Therefore, the target master cylinder pressure is automatically adjusted according to the wheel slip rate of each wheel, so that the wheel slip rate of each wheel is between the first threshold value and the second threshold value, and the vehicle can be quickly stopped without locking.
Alternatively, as shown in fig. 3, the step S102 of adjusting the target master cylinder pressure according to the magnitude of the wheel slip ratio of each wheel until the wheel slip ratio of each wheel is between the first threshold value and the second threshold value includes:
s1021, if the wheel slip ratio of one wheel is larger than or equal to a third threshold value, obtaining target braking force corresponding to the current wheel slip ratio of each wheel, and selecting the minimum target braking force as a first target master cylinder pressure until the wheel slip ratio of each wheel is smaller than the third threshold value;
wherein the third threshold value is preferably 25%.
It should be noted that, in the running process of the vehicle, as long as the wheel slip ratio of one wheel is greater than or equal to 25%, the target braking force corresponding to the wheel slip ratios of the four wheels at present is obtained, wherein a relationship curve between the wheel slip ratio and the target braking force can be calibrated in advance, the target braking force can be obtained according to the current wheel slip ratio of the wheel and the relationship curve between the wheel slip ratio and the target braking force, the minimum target braking force of the four target braking forces is selected as a first target master cylinder pressure, and the brake master cylinder adjusts the brake fluid output by the hydraulic piston according to the first target master cylinder pressure, so as to adjust the output braking force, and further change the wheel slip ratio of each wheel. And repeating the steps until the wheel slip ratio of each wheel is smaller than a third threshold value.
S1022, if the wheel slip ratio of one wheel is larger than or equal to the second threshold value, acquiring target braking force corresponding to the current wheel slip ratio of each wheel, and selecting the minimum target braking force as second target master cylinder pressure until the wheel slip ratio of each wheel is smaller than the second threshold value;
among them, the second threshold value is preferably 20%.
And after the wheel slip rate of each wheel is smaller than a third threshold value, starting the following steps, and obtaining the current corresponding target braking force of the wheel slip rates of the four wheels as long as the wheel slip rate of one wheel is larger than or equal to 20%, wherein a relation curve of the wheel slip rate and the target braking force can be calibrated in advance, the target braking force can be obtained according to the current wheel slip rate of the wheel and the relation curve of the wheel slip rate and the target braking force, the minimum target braking force in the four target braking forces is selected as a second target master cylinder pressure, and the brake master cylinder adjusts the brake fluid output by the hydraulic piston according to the second target master cylinder pressure, so that the output braking force is adjusted, and the wheel slip rate of each wheel is changed. And repeating the steps until the wheel slip ratio of each wheel is smaller than the second threshold value.
S1023, if the wheel slip ratio of one wheel is smaller than a first threshold value, acquiring target braking force corresponding to the current wheel slip ratio of each wheel, selecting the minimum target braking force as third target master cylinder pressure, and increasing the third target master cylinder pressure by a preset value as fourth target master cylinder pressure until the wheel slip ratio of each wheel is larger than or equal to the first threshold value; the third threshold value is larger than the second threshold value, and the second threshold value is larger than the first threshold value.
Wherein the first threshold value is preferably 10%. The preset value is preferably 2 bar.
It should be noted that, after the wheel slip ratio of each wheel is smaller than the second threshold, the following steps are started, and as long as the wheel slip ratio of one wheel is smaller than 10%, the target braking force corresponding to the wheel slip ratios of the four wheels at present is obtained, wherein a relationship curve between the wheel slip ratio and the target braking force may be calibrated in advance, the target braking force may be obtained according to the current wheel slip ratio of the wheel and the relationship curve between the wheel slip ratio and the target braking force, the minimum target braking force of the four target braking forces is selected as a third target master cylinder pressure, and the brake master cylinder adjusts the brake fluid output by the hydraulic piston according to the third target master cylinder pressure and a fourth target master cylinder pressure increased by a preset value, so as to adjust the output braking force, thereby changing the wheel slip ratio of each wheel. And repeating the steps until the wheel slip ratio of each wheel is greater than or equal to a first threshold value.
Therefore, the wheel slip ratio of each wheel can be adjusted between the first threshold value and the second threshold value through the adjustment, the system can be automatically adjusted according to the adjustment condition and the judgment condition based on the decoupling type electric power-assisted brake system, and the pedal feeling of the driver side is not obviously changed.
Alternatively, as shown in fig. 4, before the wheel slip ratio of each wheel is obtained, that is, before step S101, the method further includes:
s103, judging whether the expected braking force of the driver is larger than a braking force threshold value, wherein the braking force threshold value is a braking force value for triggering the ABS or the ESC;
s104, if the expected braking force of the driver is larger than the braking force threshold value, judging whether the vehicle state is in a dynamic state;
if the vehicle is in a dynamic state, the wheel slip ratio of each wheel is acquired.
Alternatively, as shown in fig. 5, before the step S103, before determining whether the desired braking force of the driver is greater than the braking force threshold value, the method further includes:
s105, acquiring the opening degree of a brake pedal;
s106, if the opening degree of the brake pedal is larger than or equal to a fourth threshold value, acquiring the expected braking force of the driver; and judging whether the expected braking force of the driver is larger than the braking force threshold value or not.
The expected braking force of the driver is in a certain proportion to the opening degree of the brake pedal, and the expected braking force of the driver can be obtained according to the opening degree of the brake pedal. The fourth threshold value is preferably 2%.
It should be noted that, when the opening degree of the brake pedal is determined to be greater than or equal to the fourth threshold value, that is, greater than or equal to 2%, this indicates that the driver is performing the braking process at this time, and it is determined that the expected braking force of the driver is greater than the braking force threshold value, which indicates that each wheel is close to locking or locking has occurred. And judging that the vehicle is in a dynamic state, which shows that the vehicle is in a dynamic running process, and avoiding false triggering in a static state. And when the three control conditions are met, setting an enable position of the anti-lock control method of the wheels, acquiring the wheel slip rate of each wheel, and adjusting the target master cylinder pressure according to the wheel slip rate of each wheel and the first, second and third threshold values to enable the wheel slip rate of each wheel to be between the first threshold value and the second threshold value.
Alternatively, as shown in fig. 6, step S104 includes:
s1041, obtaining a first wheel speed of the wheel, and calculating a vehicle speed according to the first wheel speed of the wheel; and if the vehicle speed is greater than a fifth threshold value, the vehicle state is in a dynamic state.
Wherein the first wheel speed of the wheel is directly obtained by a wheel speed sensor of the vehicle.
Alternatively, as shown in fig. 7, step S104 includes:
s1042, obtaining wheel speed pulses of the wheels, and calculating second wheel speeds of the wheels according to the wheel speed pulses of the wheels; the vehicle speed is calculated from the second wheel speed of the wheel, and the vehicle state is in a dynamic state if the vehicle speed is greater than a fifth threshold value (preferably 1 m/s).
Wherein, the second wheel speed can be obtained according to the wheel speed pulse of wheel, and the wheel speed pulse accessible wheel speed pulse sensor obtains.
It should be noted that, if the difference between the first wheel speed and the second wheel speed is greater than or equal to a seventh threshold value (preferably 2.5m/s), it is determined that the first wheel speed and/or the second wheel speed is unreliable, and therefore the wheel speed is not used and the vehicle speed obtained from the wheel speed is used to determine whether the vehicle is in a dynamic state. That is, the difference between the first wheel speed obtained by the wheel speed sensor and the second wheel speed obtained by the wheel speed pulse is larger, which indicates that there is one or both of the two values are not reliable, so that the vehicle speed is obtained by the first wheel speed or the second wheel speed only when the difference is smaller than the seventh threshold value, and the vehicle state is controlled by other methods when the values of the two values are not reliable.
The other method for controlling the vehicle state comprises the following steps: and acquiring the acceleration change rate of the vehicle, wherein if the acceleration change rate of the vehicle is greater than a sixth threshold value, the vehicle is in a dynamic state, and because the first wheel speed value and the second wheel speed value are not credible at the moment, the wheel slip rate of each wheel is not calculated, and the target master cylinder pressure is directly limited below the rear wheel locking pressure. Wherein, the sixth threshold may be 20%. The acceleration of the vehicle may be acquired from an acceleration sensor, and the period of the rate of change of the acceleration of the vehicle is the period of acquiring the acceleration from the acceleration sensor.
Fig. 8 is a flowchart of a wheel anti-lock control method according to an embodiment of the present invention. As shown in fig. 8, the wheel anti-lock control method includes:
s201, starting to acquire the opening degree of a brake pedal;
s202, judging whether the opening degree of the brake pedal is greater than or equal to a fourth threshold value; if yes, go to step S203; if not, returning to the step S201;
s203, acquiring the expected braking force of the driver;
s204, judging whether the expected braking force of the driver is larger than a braking force threshold value; if yes, go to step S205; if not, returning to the step S203;
s205, judging whether the vehicle is in a dynamic state; if yes, go to step S206; if not, returning to the step S205;
s206, obtaining the wheel slip rate of each wheel;
s207, judging whether the wheel slip rate of one wheel in each wheel is larger than or equal to a third threshold value; if yes, go to step S208; if not, go to step S209;
s208, obtaining target braking force corresponding to the current wheel slip rate of each wheel, selecting the minimum target braking force as a first target master cylinder pressure, and returning to the step S207;
s209, judging whether the wheel slip ratio of one wheel in each wheel is greater than or equal to a second threshold value; if yes, go to step S210; if not, go to step S211;
s210, obtaining target braking force corresponding to the current wheel slip rate of each wheel, selecting the minimum target braking force as a second target master cylinder pressure, and returning to the step S209;
s211, judging whether the wheel slip rate of one wheel in each wheel is smaller than a first threshold value; if yes, go to step S212; if not, go to step S213;
s212, obtaining target braking force corresponding to the current wheel slip ratio of each wheel, selecting the minimum target braking force as third target master cylinder pressure, increasing the third target master cylinder pressure by a preset value as fourth target master cylinder pressure, and returning to the step S211;
s213, determining whether the fourth target master cylinder pressure is less than the driver' S desired braking force; if yes, go to step S214; if not, the process is ended.
And S214, controlling the hydraulic piston to output the braking force by using the fourth target master cylinder pressure, and ending.
As shown in fig. 9, step S205 includes:
s2051, acquiring a first wheel speed of a wheel;
s2052, obtaining wheel speed pulses of the wheels, and calculating second wheel speeds of the wheels according to the wheel speed pulses of the wheels;
s2053, calculating a difference value between the first wheel speed and the second wheel speed;
s2054, judging whether the difference value is smaller than a seventh threshold value; if yes, go to step S2055, if no, go to step S2057;
s2055, acquiring the vehicle speed of the vehicle according to the first wheel speed or the second wheel speed;
s2056, judging whether the vehicle speed is greater than a fifth threshold value; if yes, go to step S206; if not, returning to the step S2051;
s2057, acquiring the acceleration change rate of the vehicle;
s2058, judging whether the acceleration change rate of the vehicle is larger than or equal to a sixth threshold value, if so, executing the step S2059, otherwise, returning to the step S2057;
s2059 restricts the target master cylinder pressure to the rear wheel locking pressure, and ends.
Fig. 10 is a block diagram of a wheel anti-lock control device according to an embodiment of the present invention, as shown in fig. 10, including:
a wheel slip ratio obtaining module 100, configured to obtain a wheel slip ratio of each wheel;
the target master cylinder pressure adjusting module 101 is configured to adjust the target master cylinder pressure according to the wheel slip ratio of each wheel until the wheel slip ratio of each wheel is between a first threshold and a second threshold, where the first threshold is smaller than the second threshold.
Alternatively, as shown in fig. 11, the target master cylinder pressure adjustment module 101 includes:
the first adjusting module 1011 is configured to, if the wheel slip ratio of one wheel is greater than or equal to a third threshold value, obtain a target braking force corresponding to the current wheel slip ratio of each wheel, and select a minimum target braking force as a first target master cylinder pressure until the wheel slip ratio of each wheel is smaller than the third threshold value;
a second adjusting module 1012, configured to, if there is a wheel slip ratio of one wheel that is greater than or equal to a second threshold, obtain a target braking force corresponding to a current wheel slip ratio of each wheel, and select a minimum target braking force as a second target master cylinder pressure until the wheel slip ratio of each wheel is smaller than the second threshold;
the third adjusting module 1013 is configured to, if the wheel slip ratio of one wheel is smaller than the first threshold value, obtain target braking forces corresponding to the current wheel slip ratio of each wheel, select a minimum target braking force as a third target master cylinder pressure, and increase the third target master cylinder pressure by a preset value as a fourth target master cylinder pressure until the wheel slip ratio of each wheel is greater than or equal to the first threshold value; the third threshold value is larger than the second threshold value, and the second threshold value is larger than the first threshold value.
Alternatively, as shown in fig. 12, the wheel anti-lock control device further includes:
the first judgment module 102 is configured to judge whether an expected braking force of a driver is greater than a braking force threshold value, where the braking force threshold value is a braking force value that triggers an ABS or an ESC;
a second determination module 103, configured to determine whether the vehicle state is in a dynamic state if the expected braking force of the driver is greater than the braking force threshold value;
if the vehicle is in a dynamic state, the wheel slip ratio of each wheel is acquired.
Alternatively, as shown in fig. 12, the wheel anti-lock control device further includes:
a brake pedal opening obtaining module 104, configured to obtain an opening of a brake pedal;
a third judging module 105, configured to obtain a desired braking force of the driver if the opening degree of the brake pedal is greater than or equal to a fourth threshold value; and judging whether the expected braking force of the driver is larger than the braking force threshold value or not.
Alternatively, as shown in fig. 13, the wheel anti-lock control device includes:
a first wheel speed acquisition module 106 for acquiring a first wheel speed of a wheel;
a vehicle speed obtaining module 107, configured to calculate a vehicle speed according to a first wheel speed of a wheel;
and the fourth judging module 108 is configured to, if the vehicle speed is greater than the fifth threshold, determine that the vehicle state is in a dynamic state.
Alternatively, as shown in fig. 13, the wheel anti-lock control device includes:
a second wheel speed obtaining module 109, configured to obtain a wheel speed pulse of the wheel, and calculate a second wheel speed of the wheel according to the wheel speed pulse of the wheel;
the vehicle speed obtaining module 107 is configured to calculate a vehicle speed according to the second wheel speed of the wheel, and if the vehicle speed is greater than a fifth threshold, the vehicle state is in a dynamic state.
Alternatively, as shown in fig. 13, the wheel anti-lock control device further includes:
a calculating module 112 for calculating a difference between the first wheel speed and the second wheel speed;
and a sixth judging module 113, configured to obtain the vehicle speed if the difference is smaller than a seventh threshold value.
In order to achieve the above object, a vehicle according to a third aspect of the present invention includes the wheel anti-lock control device.
In summary, according to the wheel anti-lock control method, the wheel anti-lock control device and the vehicle provided by the embodiment of the invention, firstly, the wheel slip ratio of each wheel is obtained; and adjusting the target master cylinder pressure according to the wheel slip rate of each wheel until the wheel slip rate of each wheel is between a first threshold value and a second threshold value, wherein the first threshold value is smaller than the second threshold value, so that the electronic power-assisted brake system still has the functions of wheel anti-lock and brake force adjustment after the whole vehicle stability system (ABS or ESC) fails, and the active safety performance of the vehicle is improved.
The product can execute the method provided by any embodiment of the invention, and has corresponding functional modules and beneficial effects of the execution method.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (9)
1. A wheel anti-lock control method characterized by comprising the steps of:
obtaining the wheel slip rate of each wheel;
and adjusting the target master cylinder pressure according to the wheel slip ratio of each wheel until the wheel slip ratio of each wheel is between a first threshold value and a second threshold value, wherein the first threshold value is smaller than the second threshold value.
2. The wheel anti-lock control method according to claim 1, wherein the adjusting the target master cylinder pressure according to the magnitude of the wheel slip ratio of each of the wheels until the wheel slip ratio of each of the wheels is between a first threshold value and a second threshold value comprises:
if the wheel slip ratio of one wheel is larger than or equal to a third threshold value, acquiring target braking force corresponding to the current wheel slip ratio of each wheel, and selecting the minimum target braking force as a first target master cylinder pressure until the wheel slip ratio of each wheel is smaller than the third threshold value;
if the wheel slip ratio of one wheel is larger than or equal to a second threshold value, acquiring target braking force corresponding to the current wheel slip ratio of each wheel, and selecting the minimum target braking force as a second target master cylinder pressure until the wheel slip ratio of each wheel is smaller than the second threshold value;
if the wheel slip ratio of one wheel is smaller than a first threshold value, acquiring target braking force corresponding to the current wheel slip ratio of each wheel, selecting the minimum target braking force as third target master cylinder pressure, and increasing the third target master cylinder pressure by a preset value as fourth target master cylinder pressure until the wheel slip ratio of each wheel is larger than or equal to the first threshold value; wherein the third threshold is greater than the second threshold, and the second threshold is greater than the first threshold.
3. The wheel anti-lock control method according to claim 1, further comprising, before said obtaining the wheel slip ratio of each wheel:
judging whether the expected braking force of a driver is larger than a braking force threshold value, wherein the braking force threshold value is a braking force value for triggering ABS or ESC;
if the expected braking force of the driver is larger than the braking force threshold value, judging whether the vehicle state is in a dynamic state;
and if the vehicle is in a dynamic state, acquiring the wheel slip rate of each wheel.
4. The wheel anti-lock control method according to claim 3, further comprising, before the determining whether the driver's desired braking force is greater than the braking force threshold value:
acquiring the opening degree of a brake pedal;
if the opening degree of the brake pedal is larger than or equal to a fourth threshold value, acquiring the expected braking force of the driver; and judging whether the expected braking force of the driver is larger than the braking force threshold value or not.
5. The wheel anti-lock control method according to claim 3, wherein the determining whether the vehicle state is in a dynamic state includes:
and acquiring a first wheel speed of the wheel, calculating the vehicle speed according to the first wheel speed of the wheel, and if the vehicle speed is greater than a fifth threshold value, keeping the vehicle state in a dynamic state.
6. The wheel anti-lock control method according to claim 5, wherein the determining whether the vehicle state is in a dynamic state includes:
and obtaining wheel speed pulses of wheels, calculating second wheel speeds of the wheels according to the wheel speed pulses of the wheels, calculating vehicle speed according to the second wheel speeds of the wheels, and if the vehicle speed is greater than a fifth threshold value, enabling the vehicle state to be in a dynamic state.
7. The wheel anti-lock control method according to claim 6, further comprising, before acquiring the vehicle speed:
and calculating the difference value between the first wheel speed and the second wheel speed, and if the difference value is smaller than a seventh threshold value, acquiring the vehicle speed.
8. An anti-lock control device for a wheel, characterized by comprising:
the wheel slip rate acquisition module is used for acquiring the wheel slip rate of each wheel;
and the target master cylinder pressure adjusting module is used for adjusting the target master cylinder pressure according to the wheel slip ratio of each wheel until the wheel slip ratio of each wheel is between a first threshold value and a second threshold value, wherein the first threshold value is smaller than the second threshold value.
9. A vehicle characterized by comprising the wheel anti-lock control device according to claim 8.
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| CN111959469B (en) | 2022-08-09 |
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