CN113525312B - Method, apparatus and storage medium for calculating wheel easy locking degree parameter - Google Patents
Method, apparatus and storage medium for calculating wheel easy locking degree parameter Download PDFInfo
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- CN113525312B CN113525312B CN202111083270.XA CN202111083270A CN113525312B CN 113525312 B CN113525312 B CN 113525312B CN 202111083270 A CN202111083270 A CN 202111083270A CN 113525312 B CN113525312 B CN 113525312B
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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
- B60T8/172—Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters
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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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Abstract
The invention relates to the field of calculation of driving parameters, and discloses a method, equipment and a storage medium for calculating an easy wheel locking degree parameter. The method comprises the following steps: in the braking process of a vehicle anti-lock braking system, acquiring the pressure stage of a target wheel cylinder corresponding to a target wheel in the current pressure cycle; calculating a maximum slip rate of the target wheel while the target wheel cylinder is in a pressure reduction stage or a pressure maintaining stage; and if the maximum slip rate is larger than a first threshold value, calculating the wheel acceleration of the target wheel in the pressure maintaining stage, and determining the easy locking degree parameter of the wheel in the current pressure period according to the wheel acceleration. The present embodiment proposes a parameter that characterizes the ease of wheel locking, and a calculation method of the parameter.
Description
Technical Field
The present invention relates to the field of calculation of driving parameters, and in particular, to a method, an apparatus, and a storage medium for calculating a wheel easy-to-lock degree parameter.
Background
The anti-lock Brake System (ABS) is used to automatically control the braking force of the Brake when the vehicle brakes, so that the wheels are not locked and are in a state of rolling and slipping to ensure the maximum adhesion between the wheels and the ground.
When the ABS executes the control of the pressure of the wheel cylinder, the difficulty degree of locking wheels is different when the road adhesion, the tire pressure, the vehicle load and the like are different, which puts different requirements on the control logic of the ABS. For example, switching control logic for asphalt pavement to ice may be less effective because wheels are more likely to lock on ice; switching the control logic applicable to a full load of the rear wheels of the truck to no load would also be undesirable because the rear wheels of the truck would lock more easily when no load than when full load. In view of the above, the present invention is particularly proposed to calculate a parameter capable of representing the degree of difficulty of locking a wheel.
Disclosure of Invention
In order to solve the technical problem, the invention provides a method, equipment and a storage medium for calculating a parameter of the degree of easy locking of a wheel, and provides a parameter for representing the degree of easy locking of the wheel and a calculation method of the parameter.
The embodiment of the invention provides a method for calculating a wheel easy locking degree parameter, which comprises the following steps:
in the braking process of a vehicle anti-lock braking system, acquiring the pressure stage of a target wheel cylinder corresponding to a target wheel in the current pressure cycle;
calculating a maximum slip rate of the target wheel while the target wheel cylinder is in a pressure reduction stage or a pressure maintaining stage;
if the maximum slip rate is larger than a first threshold value, calculating the wheel acceleration of the target wheel in the pressure maintaining stage, and determining the wheel easy-to-lock degree parameter of the current pressure cycle according to the wheel acceleration; wherein the value of the wheel acceleration is inversely related to the wheel easy-to-lock degree parameter;
wherein the wheel easy-to-lock degree parameter is used for adjusting a braking strategy.
An embodiment of the present invention provides an electronic device, including:
a processor and a memory;
the processor is used for executing the steps of the method for calculating the wheel locking easiness parameter according to any embodiment by calling the program or the instructions stored in the memory.
Embodiments of the present invention provide a computer-readable storage medium storing a program or instructions for causing a computer to execute the steps of the method for calculating a wheel locking susceptibility parameter according to any one of the embodiments.
The embodiment of the invention has the following technical effects:
in the embodiment, it is determined that when the maximum slip rate is large enough, the wheel acceleration in the pressure maintaining stage is used for measuring whether the wheel is easy to lock, and the obtained parameter of the degree of the wheel easy to lock can be scientifically and reasonably applied to an ABS control strategy, so that the braking safety is improved, and the wheel locking is avoided.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a flowchart of a method for calculating a wheel locking easiness parameter according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of the alarm area division provided by the embodiment of the invention;
FIG. 3 is a schematic diagram of a force balance of a target wheel according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of wheel speeds and vehicle speeds on different roads during ABS control provided by an embodiment of the present invention;
FIG. 5 is a schematic diagram of a calculation start point of a pressure holding stage according to an embodiment of the present invention;
FIG. 6 is a real vehicle test curve of a prior ABS control strategy provided by an embodiment of the present invention on an ice surface;
FIG. 7 is a real vehicle test curve on ice after strategy adjustment;
FIG. 8 is a schematic diagram of vehicle speed and wheel speed for switching ice to asphalt pavement according to an embodiment of the present invention.
Fig. 9 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The method for calculating the parameter of the degree of easy locking of the wheel is mainly suitable for adjusting the braking strategy of the ABS by calculating the parameter of the degree of easy locking of the wheel in the ABS braking process. The method for calculating the wheel easy locking degree parameter provided by the embodiment of the invention can be executed by electronic equipment.
Fig. 1 is a flowchart of a method for calculating a wheel locking easiness parameter according to an embodiment of the present invention. Referring to fig. 1, the method for calculating the wheel easy locking degree parameter specifically includes:
and S110, in the braking process of an anti-lock braking system of the vehicle, obtaining the pressure stage of the target wheel cylinder corresponding to the target wheel in the current pressure cycle.
Fig. 2 is a schematic diagram of pressure stages of a wheel cylinder in an ABS control process according to an embodiment of the present invention, where the abscissa is time and the ordinate is speed. In the ABS control process, the vehicle speed is always in a descending trend, the wheel speed is faster reduced than the vehicle speed in a wheel cylinder pressurization stage, pressure reduction is started when the slip ratio is larger after pressurization, the pressure reduction is changed into a pressure maintaining state when the wheel speed starts to rise until the wheel speed rises to be closer to the vehicle speed, and the slip ratio is very small until the next increase and decrease guarantee cycle is started.
In the present embodiment, it is necessary to calculate a wheel locking easiness degree parameter of each wheel in each pressure cycle, and taking a four-wheel vehicle as an example, the target wheel is any one of the wheels, each wheel corresponds to a wheel cylinder, and the wheel cylinder may be in a pressure increasing stage, a pressure reducing stage or a pressure maintaining stage. In practical application scenarios, the pressure increasing stage, the pressure reducing stage or the pressure maintaining stage can be determined according to the opening and closing states of the wheel cylinder control valves or the collected values of the pressure sensors in the wheel cylinders.
And S120, when the target wheel cylinder is in a pressure reduction stage or a pressure maintaining stage, calculating the maximum slip rate of the target wheel.
Referring to fig. 2, the target wheel cylinder undergoes a long-time pressure reduction before the pressure maintaining stage, so the actual pressure during pressure maintaining is very low and can be ignored; the frictional force F of the road surface against the target wheel can represent the degree of easy locking of the wheel. Specifically, when the friction force F is larger, a larger braking force is required to stop the wheels, and the wheels are not easily locked; when the friction force F is small, the wheel can be locked by small braking force, so that the degree of easy locking can be represented by the friction force F of the road surface to the target wheel and is negatively related to the degree of easy locking.
Fig. 3 is a schematic diagram of the force balance of the target wheel according to the embodiment of the present invention. The moment of inertia of the target wheel is J, the rolling radius is r, the road adhesion coefficient is F, the weight distribution of the whole vehicle on a single wheel is mg, and F = mg F. The formula of the stress balance in the wheel rotation direction in the pressure maintaining stage is mgfr = J a/r, and F = mgf = J a/r can be deduced2. After the wheels are determined, r and J are fixed and unchanged, so that the acceleration a of the wheels is in direct proportion to the friction force F of the road surface to the target wheels, namely a is obtained, the corresponding degree of easy locking of the wheels can be obtained, and the larger a is, the less easy locking of the wheels is.
In actual control, the wheel speed does not change at a significant rate for each incremental or decremental guard cycle. FIG. 4 is a schematic diagram of wheel speeds and vehicle speeds on different roads during ABS control according to an embodiment of the present invention. When the wheel speed is short in duration of the pressure maintaining stage, the rising data points of the wheel speed are few, and the real degree of easy locking of the wheel cannot be represented by the calculated wheel acceleration. However, when the vehicle is on the ice surface, the slip rate of the wheel is relatively large, the wheel speed slowly rises, the wheel speed rising data points are relatively large, and the wheel acceleration obtained through calculation can represent the real degree of easy locking of the wheel. Based on the above analysis, the slip rate of the target wheel cylinder in the pressure reduction stage or the pressure maintaining stage in each pressure cycle is calculated in real time, and the maximum slip rate is selected from all slip rates calculated in the pressure reduction stage and the pressure maintaining stage. The greater the maximum slip rate, the more the wheel is susceptible to locking, depending on the wheel acceleration (i.e., the wheel speed rising slope). For this purpose, a first threshold value is set in advance, and the maximum slip ratio is compared with the first threshold value. The first threshold value may be obtained by calibration or by human setting, for example 35%.
S130, if the maximum slip rate is larger than a first threshold value, calculating the wheel acceleration of the target wheel in the pressure maintaining stage, and determining the easy locking degree parameter of the wheel in the current pressure period according to the wheel acceleration; wherein the wheel easy-to-lock degree parameter is used for adjusting a braking strategy.
And if the maximum slip rate is larger than the first threshold value, determining the wheel locking easiness degree parameter of the target wheel in the current pressure period completely depending on the wheel acceleration. First, accurate wheel acceleration calculation is required.
Fig. 5 is a schematic diagram of a calculation starting point of the pressure holding stage according to the embodiment of the present invention. Referring to fig. 5, the slope of the rise in the wheel speed during the pressure holding period is the wheel acceleration of the target wheel. Therefore, the wheel speed in a proper time period can be taken in the pressure maintaining stage to calculate the rising slope as the wheel acceleration of the target wheel, so as to obtain a more reasonable wheel easy locking degree parameter. Since the wheel speed rises more slowly at a low speed, which has an adverse effect on the calculation result of the rising slope of the wheel speed, a plurality of wheel speeds after the wheel speed rises to a set value in the pressure holding stage are recorded. The set value may be calibrated or set manually, for example, the set value is 1/4 or half of the maximum wheel speed of the current pressure cycle (i.e. the wheel speed at the beginning of the current pressure cycle), and the set value is used as the starting point of the wheel speed rising slope calculation, see fig. 5. After the starting point is calculated, acquiring a wheel speed value in each subsequent sampling period, and calculating the slope of each wheel speed in a plurality of wheel speeds with respect to the set value; the maximum value of the slopes is used as the wheel acceleration of the target wheel. Because the acceleration of the wheel is large, the wheel speed rises quickly, namely the locking degree is low, the acceleration of the wheel is larger, and the subsequent pressurizing time is earlier; conversely, if a small slope is obtained, the wheel acceleration is slightly small, the boosting timing is late, locking may occur early, the braking force is insufficient late, and the braking force is insufficient during braking and is more dangerous than the locking of the wheel, so a large wheel acceleration value is preferred.
Because the value range of the slope is larger, in order to more reasonably apply the wheel easy locking degree parameter to the ABS braking strategy, the wheel acceleration is normalized to obtain the wheel easy locking degree parameter of the current pressure period. The value of the wheel acceleration is in negative correlation with the wheel easy locking degree parameter, namely the larger the wheel acceleration is, the smaller the determined wheel easy locking degree parameter is, and the wheel is less prone to locking; therefore, the corresponding relation between the wheel acceleration and the wheel easy-to-lock degree parameter is preset, for example, the slope 1000 corresponds to the wheel easy-to-lock degree parameter 5, the slope 500 corresponds to the wheel easy-to-lock degree parameter 10, and the wheel easy-to-lock degree parameter of the current pressure cycle is obtained by searching the corresponding relation.
The wheel locking is a result of combined action of braking force on a brake disc and road surface friction force, when the braking force on the brake disc is fixed, the larger the friction force of a road surface to a wheel is, the wheel is not easy to lock, the smaller the friction force of the road surface to the wheel is, the wheel is easy to lock, so the road surface friction force can represent the wheel locking degree, and the road surface friction force of the wheel = the pressure of the wheel to the road surface and the adhesion coefficient, which are referred to in the above description, so the key point of the invention is not to calculate wheel acceleration, but to evaluate whether the wheel is easy to lock. The inventor determines whether the wheel is easy to lock or not by the wheel acceleration in the pressure maintaining stage when the maximum slip rate is large enough according to scientific and reasonable analysis, and the obtained parameter of the degree of the easy-to-lock of the wheel can be scientifically and reasonably applied to an ABS control strategy.
Road adhesion and tire pressure determine the adhesion coefficient, vehicle load, axle load distribution, and single wheel load distribution determine the pressure of the wheel against the road surface, so road friction is the result of these co-actions, and the degree of wheel locking can be directly and unambiguously obtained as a result of these co-actions. Therefore, the embodiment of the invention normalizes the variables influencing ABS control, such as road surface adhesion, vehicle load, axle load distribution, single wheel load distribution, tire pressure and the like, into the degree of easy locking of the wheels, and uses the degrees as the reference of an ABS control strategy.
The existing ABS control strategy generally sets uniform road adhesion, and the vehicle load is difficult to accurately obtain, so that the existing ABS control strategy is difficult to obtain the optimal control effect. Braking strategies include, but are not limited to, boost timing and braking force for each wheel.
In this embodiment, when the wheel easy locking degree parameter of the target wheel is smaller, the locking is less easy; when the parameter is larger, the easier it is to lock. Moreover, referring to the wheel speed curve of the asphalt road in fig. 4, in practice, after pressure reduction is finished and pressure maintaining is started, the wheel speed rises very fast, about several tens of milliseconds, so that for the condition that the wheel locking degree parameter is small, pressurization is started in advance, and when the wheel speed rises to the highest point, the actual pressure is increased; if the wheel starts to be pressurized after the wheel speed rises to the highest point, the wheel has no braking force during the period of increasing the actual pressure, the braking strength is insufficient, and danger is caused. Based on the above two considerations, the boost timing of the ABS control strategy is earlier when the parameter is smaller than when the parameter is larger.
In another alternative embodiment, the vehicle runs on a split road surface, the ground adhesion force of the left wheel and the ground adhesion force of the right wheel are different, for example, the left wheel runs on an ice surface, the right wheel runs on an asphalt road surface, and the vehicle is easy to deviate and lose control when braking. In the embodiment, the parameters of the degree of easy locking of two wheels can be known to be different by calculating the acceleration of the wheels, when the braking force applied to the wheels on the road is smaller than the maximum braking force, the magnitude of the braking force depends on the wheel cylinder pressure, the wheel cylinder pressures of the wheels are adjusted to be the same or the difference value is within a set range (for example, the pressure difference value is within 0.01MPa under the condition that the stressed areas of the wheel cylinders of the wheels are the same), that is, the wheel cylinder pressures are relatively close to each other, so that the braking force of the wheels is within the set range, that is, the braking force of the wheels is the same or similar, the braking force of the road to the wheels is ensured to be equivalent, and the vehicle is braked smoothly.
Fig. 6 is a real vehicle test curve of a conventional ABS control strategy provided by an embodiment of the present invention on an ice surface, and fig. 7 is a real vehicle test curve of the strategy adjusted on the ice surface. The lowermost test curve is the longitudinal acceleration of the vehicle. In FIG. 6, the wheel speed does not rise due to the timing of the pressure increase being too earlyThe vehicle speed is calculated according to the upper envelope line of the wheel speed, so that the vehicle speed value is lower and lower, and the wheel slip rate is increased until the wheel is locked. It can be seen that the vehicle starts to lock from the 21 st second and stops until the vehicle coasts for 33 seconds, at which time the longitudinal deceleration of the vehicle is approximately 1m/s2. In fig. 7, the boosting opportunity is delayed according to the parameter of the degree of easy locking of the wheel, the wheel speed and the vehicle speed both slowly decrease, and the control effect of the wheel is good.
In the embodiment, it is determined that when the maximum slip rate is large enough, the wheel acceleration in the pressure maintaining stage is used for measuring whether the wheel is easy to lock, and the obtained parameter of the degree of the wheel easy to lock can be scientifically and reasonably applied to an ABS control strategy, so that the braking safety is improved, and the wheel locking is avoided.
On the basis of the embodiment, different calculation methods of the wheel locking easiness degree parameters are adopted in different maximum slip rate intervals. When the maximum slip rate is larger, the parameter of the easy locking degree of the wheel depends on the rising slope of the wheel speed; when the maximum slip rate is small, the calculation result of the parameter of the degree of easy locking of the wheel should be more dependent on the calculation result of the previous pressure cycle. There are several specific situations.
In the first case: and if the maximum slip rate is smaller than or equal to the first threshold and larger than the second threshold, determining an initial wheel easy-locking degree parameter according to the wheel acceleration in the pressure maintaining stage, and obtaining the wheel easy-locking degree parameter of the current pressure cycle according to the maximum slip rate, the initial wheel easy-locking degree parameter and the wheel easy-locking degree parameter of the previous pressure cycle.
This applies to the case of snow surfaces and the like where the slip ratio is relatively high, and the second threshold value may be calibrated, for example to 25%, while the degree of wheel tendency to lock depends on the wheel acceleration and the previous pressure cycle, but is determined by the maximum slip ratio. Optionally, determining a weight Temp according to the positions of the maximum slip ratio M in the first threshold a1 and the second threshold a 2; selecting the smaller Q of the initial wheel easy locking degree parameter Qi and the wheel easy locking degree parameter Qi-1 of the previous pressure period; and weighting the smaller Q and the initial wheel easy-to-lock degree parameter Qi by adopting the weight Temp to obtain a wheel easy-to-lock degree parameter U of the current pressure cycle. The formula is as follows:
Temp=（M-A2）/（A1-A2）
Q=min（Qi，Qi-1）
U=Temp*Qi+（1-Temp）*Q
and in the second situation, if the maximum slip rate is smaller than or equal to a second threshold and larger than a third threshold, determining an initial easy wheel locking degree parameter according to the wheel acceleration in the pressure maintaining stage, and obtaining the easy wheel locking degree parameter of the current pressure period according to the initial easy wheel locking degree parameter and the easy wheel locking degree parameter of the previous pressure period.
This is applicable to the case of a moderate slip rate such as road surface water accumulation, and the third threshold value can be obtained by calibration, for example, 20%, and depends on the degree of easy locking of the wheel during the wheel acceleration and the previous pressure cycle. Optionally, the smaller of the initial wheel easy locking degree parameter and the wheel easy locking degree parameter of the previous pressure cycle is taken as the wheel easy locking degree parameter of the current pressure cycle. The more difficult the wheels are locked, the earlier the subsequent pressurizing time is; on the contrary, the more easily the wheels are locked, the later the pressurizing time is, the earlier the pressurizing time is, locking may be caused, the later the braking force is insufficient, the braking force is insufficient in the braking process and is more dangerous than the locking of the wheels, so the condition that the degree of easy locking of the wheels is lower is preferentially selected, namely the parameter of the degree of easy locking of the wheels is smaller.
In the third case: and if the maximum slip rate is smaller than or equal to a third threshold and larger than a fourth threshold, obtaining the parameter of the degree of the easy locking of the wheel in the current pressure cycle according to the maximum slip rate and the parameter of the degree of the easy locking of the wheel in the previous pressure cycle.
This applies to the case where the slip rate of a road surface with fine sand and gravel is relatively low, and the fourth threshold value can be calibrated, for example, to 15%. Referring to fig. 4, when the slip ratio is relatively small, the wheel speed rise data points are few, so that the wheel acceleration obtained through calculation cannot represent the real easy-locking degree of the wheel, and therefore the wheel acceleration obtained through calculation is not trusted, but the easy-locking degree parameter of the wheel in the previous pressure cycle is trusted. The confidence level is determined according to the maximum slip rate. Further, the parameter of the easy wheel locking degree of the current pressure cycle is obtained according to the previous time. Referring to fig. 8, it is assumed that the vehicle may run on an ice surface in the previous pressure cycle, and when the vehicle is switched to a road surface with fine sand and gravel, the calculation result completely depending on the previous pressure cycle is obviously incorrect, and the parameter of the current pressure cycle can be estimated to be smaller than the calculation result of the previous pressure cycle, so as to estimate the parameter of the current pressure cycle; and further calculating the weight according to the maximum slip rate.
Specifically, determining a weight Temp according to the positions of the maximum slip ratio in the third threshold and the fourth threshold; subtracting the calibration value b from the wheel easy locking degree parameter Qi-1 of the previous pressure period to obtain an estimated value M of the wheel easy locking degree parameter; and weighting the estimated value M and the wheel easy-to-lock degree parameter of the previous pressure cycle by adopting the weight Temp to obtain the wheel easy-to-lock degree parameter U of the current pressure cycle. Illustratively, the calibration value may be 20. The formula is as follows:
Temp=（M-A4）/（A3-A4）
U=Temp*Qi-1+（1-Temp）*M
in a fourth case: if the maximum slip rate is less than or equal to a fourth threshold value, obtaining a wheel easy locking degree parameter of the current pressure cycle according to the wheel easy locking degree parameter of the previous pressure cycle;
this is the case for very low slip rates such as asphalt roads, and the fourth threshold can be calibrated, for example, to 15%. And subtracting the calibrated value from the wheel easy locking degree parameter of the previous pressure cycle to obtain the wheel easy locking degree parameter of the current pressure cycle. This situation is completely dependent on the parameters obtained from the previous pressure cycle.
It should be noted that the reason why the calibration value is subtracted in the fourth case is that the smaller the parameter of the degree of easy locking of the wheel is, the less easy locking of the wheel is, and the greater the probability that the maximum slip rate is small when the wheel is, so that when the maximum slip rate is small, the wheel is considered to be very difficult to lock, and therefore the parameter of the degree of easy locking of the wheel is reduced from the original value, so the calibration value is subtracted. If the road surface is always in low adhesion after being switched from high adhesion to low adhesion, the low adhesion is easy to lock, so that the maximum slip rate of each pressure cycle is very large, and the threshold range of the fourth condition is not met; if the road surface is always in high adhesion after being switched from low adhesion to high adhesion, the parameter of the easy locking degree is subtracted by the calibration value one by one. Such as 20, starting at 100 for a period, to a minimum limit of the easy-to-lock parameter, such as 0.
In the above four cases, the second threshold is smaller than the first threshold, the third threshold is smaller than the second threshold, and the fourth threshold is smaller than the third threshold. The initial wheel easy-to-lock degree parameter is obtained from the wheel acceleration (i.e., the wheel speed slope), and the calculation method is the same as that in S130. However, in these four cases, in order to distinguish from the final wheel locking tendency parameter, the parameter obtained from the wheel acceleration is referred to as an initial wheel locking tendency parameter.
In this embodiment, when the maximum slip ratio is not large enough, the degree of easy locking of the wheel cannot be estimated through the wheel speed slope, and then a parameter of the degree of easy locking of the wheel can be estimated by using the above four processing methods, which can support the reasonable execution of the ABS control logic.
The first threshold, the second threshold, the third threshold and the fourth threshold are designed to reasonably divide the maximum slip rate, so that the maximum slip rate is divided into different ranges, and different algorithms are adopted to calculate the parameter of the degree of easy locking of the wheel. The present embodiment does not limit the setting method of these 4 thresholds. Optionally, the 4 thresholds are calibrated in a real vehicle test mode. For example, if a plurality of vehicles are on different road surfaces, but other parameters are the same, the real size relationship of the wheel anti-lock degree parameters of the plurality of vehicles can be known, and 4 thresholds are set and adjusted, so that the calculated size relationship of the wheel anti-lock degree parameters matches with the real size relationship, and the appropriate 4 thresholds are obtained.
Fig. 9 is a schematic structural diagram of an electronic device according to an embodiment of the present invention. As shown in fig. 9, the electronic device 400 includes one or more processors 401 and memory 402.
The processor 401 may be a Central Processing Unit (CPU) or other form of processing unit having data processing capabilities and/or instruction execution capabilities, and may control other components in the electronic device 400 to perform desired functions.
In one example, the electronic device 400 may further include: an input device 403 and an output device 404, which are interconnected by a bus system and/or other form of connection mechanism (not shown). The input device 403 may include, for example, a keyboard, a mouse, and the like. The output device 404 can output various information to the outside, including warning prompt information, braking force, etc. The output devices 404 may include, for example, a display, speakers, a printer, and a communication network and its connected remote output devices, among others.
Of course, for simplicity, only some of the components of the electronic device 400 relevant to the present invention are shown in fig. 9, omitting components such as buses, input/output interfaces, and the like. In addition, electronic device 400 may include any other suitable components depending on the particular application.
In addition to the above-described methods and apparatus, embodiments of the present invention may also be a computer program product comprising computer program instructions which, when executed by a processor, cause the processor to perform the steps of the method of calculating a wheel locking susceptibility parameter as provided by any of the embodiments of the present invention.
The computer program product may write program code for carrying out operations for embodiments of the present invention in any combination of one or more programming languages, including an object oriented programming language such as Java, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computing device, partly on the user's device, as a stand-alone software package, partly on the user's computing device and partly on a remote computing device, or entirely on the remote computing device or server.
Furthermore, an embodiment of the present invention may also be a computer-readable storage medium having stored thereon computer program instructions, which, when executed by a processor, cause the processor to perform the steps of the method for calculating a wheel locking easiness parameter provided by any of the embodiments of the present invention.
The computer-readable storage medium may take any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may include, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or a combination of any of the foregoing. More specific examples (a non-exhaustive list) of the readable storage medium include: an electrical connection having one or more wires, a portable disk, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.
It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present application. As used in the specification and claims of this application, the terms "a," "an," "the," and/or "the" are not intended to be inclusive in the singular, but rather are intended to be inclusive in the plural, unless the context clearly dictates otherwise. The terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method or apparatus that comprises the element.
It is further noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," and the like are used in the orientation or positional relationship indicated in the drawings for convenience in describing the invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the invention. Unless expressly stated or limited otherwise, the terms "mounted," "connected," "coupled," and the like are to be construed broadly and encompass, for example, both fixed and removable coupling or integral coupling; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention.
Claims (10)
1. A method for calculating a wheel locking easiness degree parameter is characterized by comprising the following steps:
in the braking process of a vehicle anti-lock braking system, acquiring the pressure stage of a target wheel cylinder corresponding to a target wheel in the current pressure cycle;
calculating a maximum slip rate of the target wheel while the target wheel cylinder is in a pressure reduction stage or a pressure maintaining stage;
if the maximum slip rate is larger than a first threshold value, calculating the wheel acceleration of the target wheel in the pressure maintaining stage, and determining the wheel easy-to-lock degree parameter of the current pressure cycle according to the wheel acceleration; wherein the value of the wheel acceleration is inversely related to the wheel easy-to-lock degree parameter;
wherein the wheel easy-to-lock degree parameter is used for adjusting a braking strategy.
2. The method according to claim 1, further comprising, after calculating the maximum slip rate of the target wheel while the target wheel cylinder is in a pressure-decreasing stage or a pressure-maintaining stage:
if the maximum slip rate is smaller than or equal to a first threshold and larger than a second threshold, determining an initial wheel easy-locking degree parameter according to the wheel acceleration in the pressure maintaining stage, and obtaining the wheel easy-locking degree parameter of the current pressure cycle according to the maximum slip rate, the initial wheel easy-locking degree parameter and the wheel easy-locking degree parameter of the previous pressure cycle;
if the maximum slip rate is smaller than or equal to a second threshold and larger than a third threshold, determining an initial wheel easy-to-lock degree parameter according to the wheel acceleration in the pressure maintaining stage, and obtaining a wheel easy-to-lock degree parameter of the current pressure cycle according to the initial wheel easy-to-lock degree parameter and a wheel easy-to-lock degree parameter of the previous pressure cycle;
if the maximum slip rate is smaller than or equal to a third threshold and larger than a fourth threshold, obtaining a wheel easy locking degree parameter of the current pressure cycle according to the maximum slip rate and the wheel easy locking degree parameter of the previous pressure cycle;
if the maximum slip rate is less than or equal to a fourth threshold value, obtaining a wheel easy locking degree parameter of the current pressure cycle according to the wheel easy locking degree parameter of the previous pressure cycle;
the second threshold is smaller than the first threshold, the third threshold is smaller than the second threshold, and the fourth threshold is smaller than the third threshold.
3. The method of claim 2, wherein obtaining the wheel easy-to-lock degree parameter for the current pressure cycle according to the maximum slip ratio, the initial wheel easy-to-lock degree parameter, and the wheel easy-to-lock degree parameter for the previous pressure cycle comprises:
determining a weight according to the position of the maximum slip ratio in the first threshold and the second threshold;
selecting the smaller of the initial wheel easy locking degree parameter and the wheel easy locking degree parameter of the previous pressure period;
and weighting the smaller one and the initial wheel easy-to-lock degree parameter by adopting the weight to obtain the wheel easy-to-lock degree parameter of the current pressure cycle.
4. The method according to claim 2, wherein obtaining the wheel easy-to-lock degree parameter for the current pressure cycle from the initial wheel easy-to-lock degree parameter and the wheel easy-to-lock degree parameter for the previous pressure cycle comprises:
and taking the smaller of the initial wheel easy locking degree parameter and the wheel easy locking degree parameter of the previous pressure cycle as the wheel easy locking degree parameter of the current pressure cycle.
5. The method according to claim 2, wherein if the maximum slip ratio is less than or equal to a third threshold and greater than a fourth threshold, obtaining the parameter of the degree of wheel easy locking for the current pressure cycle according to the maximum slip ratio and the parameter of the degree of wheel easy locking for the previous pressure cycle comprises:
if the maximum slip rate is smaller than or equal to a third threshold and larger than a fourth threshold, determining a weight according to the position of the maximum slip rate in the third threshold and the fourth threshold;
subtracting the calibrated value from the wheel easy locking degree parameter of the previous pressure period to obtain an estimated value of the wheel easy locking degree parameter;
and weighting the estimated value and the wheel easy-locking degree parameter of the previous pressure cycle by adopting the weight to obtain the wheel easy-locking degree parameter of the current pressure cycle.
6. The method according to claim 2, wherein if the maximum slip ratio is less than or equal to a fourth threshold, obtaining the parameter of the degree of wheel easy locking for the current pressure cycle according to the parameter of the degree of wheel easy locking for the previous pressure cycle comprises:
and if the maximum slip rate is less than or equal to a fourth threshold value, subtracting a calibration value from the wheel easy-locking degree parameter of the previous pressure cycle to obtain the wheel easy-locking degree parameter of the current pressure cycle.
7. The method according to claim 1, wherein the calculating the wheel acceleration of the target wheel during the pressure holding period if the maximum slip ratio is greater than a first threshold value comprises:
if the maximum slip rate is larger than a first threshold value, recording a plurality of wheel speeds after the wheel speed rises to a set value in the pressure maintaining stage;
calculating a slope from the set value for each of the plurality of wheel speeds;
the maximum value of the slopes is used as the wheel acceleration of the target wheel.
8. The method according to any one of claims 1-7, further comprising, after determining the wheel easy-to-lock parameter for the current pressure cycle from the wheel acceleration:
adjusting the pressurization opportunity of the current pressure cycle according to the wheel easy locking degree parameter of the current pressure cycle; and/or the presence of a gas in the gas,
and adjusting the braking force of each wheel according to the wheel locking easiness degree parameter of each wheel in the current pressure period so as to enable the braking force of each wheel to be within a set range.
9. An electronic device, characterized in that the electronic device comprises:
a processor and a memory;
the processor is configured to execute the steps of the method for calculating a wheel locking easiness parameter according to any one of claims 1 to 8 by calling a program or instructions stored in the memory.
10. A computer-readable storage medium, characterized in that it stores a program or instructions for causing a computer to execute the steps of the method of calculating a wheel locking easiness parameter according to any one of claims 1 to 8.
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