CN116753827A - Calibration method of brake pedal travel sensor - Google Patents
Calibration method of brake pedal travel sensor Download PDFInfo
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- CN116753827A CN116753827A CN202310850907.6A CN202310850907A CN116753827A CN 116753827 A CN116753827 A CN 116753827A CN 202310850907 A CN202310850907 A CN 202310850907A CN 116753827 A CN116753827 A CN 116753827A
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- 238000006073 displacement reaction Methods 0.000 claims abstract description 28
- 230000008569 process Effects 0.000 claims abstract description 17
- 230000008859 change Effects 0.000 claims abstract description 12
- 238000005314 correlation function Methods 0.000 claims description 12
- 238000004364 calculation method Methods 0.000 claims description 9
- 238000004088 simulation Methods 0.000 claims description 5
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- 238000012795 verification Methods 0.000 claims description 3
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
Abstract
The application discloses a calibration method of a brake pedal travel sensor, which comprises the following steps of calibrating a structure zero point; by the adoption of the calibration method of the brake pedal stroke sensor, a zero magnetic field reference angle is introduced into the stroke sensor, a corresponding relation is established between an output signal of the stroke sensor and the zero magnetic field reference angle, at the moment, although the actual magnetic field angle of a structure zero point is not fixed, the zero magnetic field reference angle can be fixed by adjusting an offset angle value, the position of a zero magnetic field reference angle abrupt change point is also adjusted to a relatively fixed position, so that the stroke sensor obtains a relatively stable displacement measurement range, the problem of abrupt change of the magnetic field angle in the motion process of a push rod is solved, and meanwhile, the size of the displacement measurement range of the stroke sensor can be adjusted by adjusting the zero reference magnetic field angle, so that the measurement interval of the stroke sensor is more flexible.
Description
Technical Field
The application relates to the technical field of sensor calibration, in particular to a calibration method of a brake pedal stroke sensor.
Background
The automobile brake booster system is an important component of a modern automobile brake system, and is mainly used for reducing the force required by a driver when the driver steps on a brake pedal and improving the efficiency and stability of the brake system.
In the prior art, related parameters are mainly written into by a burner in the calibration of a travel sensor in an automobile brake booster system, and a specific calibration method mostly adopts two-point calibration or multi-point calibration, namely, two or more known position points are selected, corresponding values output by the sensor are recorded, and a linear or nonlinear mathematical model is established according to input values and output values of the position points, so that the output of the sensor is converted into the corresponding position values.
However, during the movement of the push rod of the automobile brake booster system, there may be a situation that the magnetic field angle is suddenly changed from 360 ° to 0 ° or from 0 ° to 360 °, if the sensor output signal directly corresponds to the actual magnetic field angle, the sudden change of the magnetic field angle may cause the sudden change of the sensor output signal. In addition, due to the difference of the magnets, the positions of the magnetic field angle mutation points are changed, the signal mutation points are also changed, and the changed signal mutation points are not preferable, so that the displacement measurement range of the sensor is uncontrollable.
Disclosure of Invention
Aiming at the defects of the prior art, the application provides a calibration method of a brake pedal stroke sensor with high measurement accuracy.
In order to achieve the above object, the present application is achieved by the following technical scheme.
The application provides a calibration method of a brake pedal travel sensor, which comprises the following steps:
building a simulation matching system of the HCU and the automobile pedal assembly, and calibrating a structural zero point when the pre-jacking pressure between the HCU electric cylinder and the push rod of the automobile pedal assembly accords with a preset pressure range;
writing configuration parameters of a SENT signal and a PWM signal into a stroke sensor of an automobile pedal assembly;
respectively configuring a SENT signal, a calibration point of a PWM signal and a target value in the stroke sensor, wherein the angle change trend of the PWM signal output value is set to be descending;
performing two-point calibration of the stroke sensor and generating a correlation function between the SENT signal, the PWM signal output value and the push rod stroke;
setting the zero magnetic field reference angles of the SENT signal and the PWM signal respectively, and calculating offset angle values of the SENT signal and the PWM signal output values between the zero magnetic field reference angles and the zero magnetic field actual angles respectively;
correcting a correlation function between a SENT signal and a PWM signal output value in the stroke sensor and the stroke of the push rod based on the offset angle;
wherein the actual angle of the zero magnetic field is the magnetic field angle at the zero position of the structure.
Further defined, in the calibration method of the brake pedal stroke sensor, the configuration parameters of the write send signal and the PWM signal include a frame length, a data bit number, a verification mode, a decoding mode, and a communication rate of the send frame;
the configuration parameters of the PWM signal comprise frequency, duty ratio, upper and lower limits of pulse width and voltage range.
Further defined, the calibration method of the brake pedal stroke sensor, wherein the performing the two-point calibration of the stroke sensor includes:
triggering a first calibration point of a travel sensor at a structure zero point position, and triggering a second calibration point when a push rod of an automobile pedal assembly extends out of a preset distance;
two SENT signal output values and two PWM signal output values of the first calibration point and the second calibration point downstroke sensor are obtained.
Further defined, the calibration method of the brake pedal stroke sensor, wherein the calculation method of the offset angle value is as follows:
offset angle value = signal output value of zero magnetic field reference angle-signal output value of zero magnetic field actual angle;
the signal output value of the actual angle of the zero magnetic field is the SENT signal/PWM signal output value of the structural zero downstroke sensor.
Further defined, in the calibration method of the brake pedal stroke sensor, for the send signal, the method for obtaining the signal output value of the zero magnetic field reference angle is as follows:
Y＝65535X/360-32768；
wherein X is the zero magnetic field reference angle of the SENT signal, and Y is the output value of the SENT signal under the zero magnetic field reference angle.
Further defined, in the calibration method of the brake pedal stroke sensor, for the PWM signal, the method for obtaining the signal output value of the zero magnetic field reference angle is:
Y＝32767-65535X/360；
wherein X is the zero magnetic field reference angle of the PWM signal, and Y is the output value of the PWM signal under the zero magnetic field reference angle.
Further defined, in the calibration method of the brake pedal stroke sensor, the zero magnetic field reference angle of the send signal is set to 35 °, and the zero magnetic field reference angle of the PWM signal is set to 325 °.
Further defined, the calibration method of the brake pedal stroke sensor, wherein the correlation function between the send signal, the PWM signal output value and the push rod stroke in the corrected stroke sensor further comprises:
acquiring a SENT/PWM signal output value of a stroke sensor under a structure zero point when a push rod of an automobile pedal assembly is in a complete release state;
comparing the CAN signal packaged by the SENT/PWM signal output value corresponding to the original signal at the structure zero point with the upper limit value/lower limit value of the corresponding zero point standard to form a judging result;
the error range between the SENT/PWM signal output value at the zero point of the structure, corresponding to the CAN signal packaged by the original signal, and the upper/lower limit value of the corresponding zero point standard is set to be not more than 0.5%.
Further defined, the calibration method of the brake pedal stroke sensor further includes:
the HCU electric cylinder moves the push rod of the automobile pedal assembly from the structure zero position by a preset stroke at a preset speed, and a SENT/PWM signal output value of the stroke sensor in the push rod moving process is obtained;
generating signal curves respectively based on CAN signals of the SENT/PWM signal output values corresponding to the original signal packages in the push rod moving process, and comparing the signal curves corresponding to the SENT/PWM signal output values with corresponding standard upper/lower limit curves to form a judging result;
when the push rod of the automobile pedal assembly moves to the preset stroke end point, the thrust of the HCU electric cylinder to the push rod of the automobile pedal assembly is not more than the rated top pressure.
Further defined, in the calibration method of the brake pedal stroke sensor, the standard upper/lower limit curve calculation function corresponding to the SENT signal output value is:
Y 1 ＝(X/25.2*3766+320)*(1±2％)；
wherein Y is 1 X is the displacement (mm) of the HCU electric cylinder relative to the structural zero point and is larger than zero;
the standard upper/lower limit curve calculation function corresponding to the PWM signal output value is as follows:
Y 2 ＝(X/25.2*73+16.1)*(1±2％)；
wherein Y is 2 And X is the displacement (mm) of the HCU electric cylinder relative to the structural zero point and is larger than zero.
The application has at least the following beneficial effects:
1. the zero magnetic field reference angle is introduced into the stroke sensor, a corresponding relation is established between the output signal of the stroke sensor and the zero magnetic field reference angle, at the moment, although the actual magnetic field angle of the structure zero point is not fixed, the zero magnetic field reference angle can be fixed by adjusting the offset angle value, and the position of the abrupt change point of the zero magnetic field reference angle is also adjusted to a relatively fixed position, so that the stroke sensor obtains a relatively stable displacement measurement range, the problem of abrupt change of the magnetic field angle in the motion process of the push rod is solved, and meanwhile, the size of the displacement measurement range of the stroke sensor can be adjusted by adjusting the zero reference magnetic field angle, so that the measurement interval of the stroke sensor is more flexible;
2. the upper limit and the lower limit of the SENT/PWM signal value output by the stroke sensor in the structure zero point and the push rod moving process are compared to ensure the measurement accuracy of the stroke sensor, and the recalibration can be performed on the unqualified stroke sensor, so that the integral calibration quality of the stroke sensor is improved.
Drawings
FIG. 1 is a flow chart of a method for calibrating a brake pedal travel sensor in accordance with an embodiment of the present application;
FIG. 2 is a schematic diagram of the "calibration system" in the calibration method of the brake pedal travel sensor according to the embodiment of the present application;
FIG. 3 is a graph showing the output value of the SENT signal of the travel sensor as a function of the angle of the magnetic field in the calibration method of the travel sensor of the brake pedal according to the embodiment of the application;
FIG. 4 is a graph showing the output value of PWM signals of a travel sensor as a function of the angle of a magnetic field in a calibration method of a travel sensor for a brake pedal according to an embodiment of the present application.
Reference numerals
The system comprises an upper computer-100, a hydraulic control unit-200, an automobile pedal assembly-300 and a burner-400.
Detailed Description
The technical solutions of the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which are obtained by a person skilled in the art based on the embodiments of the present application, fall within the scope of protection of the present application.
The terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged, as appropriate, such that embodiments of the present application may be implemented in sequences other than those illustrated or described herein, and that the objects identified by "first," "second," etc. are generally of a type, and are not limited to the number of objects, such as the first object may be one or more. Furthermore, in the description and claims, "and/or" means at least one of the connected objects, and the character "/", generally means that the associated object is an "or" relationship.
The calibration method of the brake pedal stroke sensor provided by the embodiment of the application is described in detail below through specific embodiments and application scenes thereof with reference to the accompanying drawings.
As shown in fig. 1, an embodiment of the present application provides a method for calibrating a brake pedal stroke sensor, including:
s1, building a simulation matching system of an HCU and an automobile pedal assembly, acquiring pre-jacking pressure between an electric cylinder of the HCU and a push rod of the automobile pedal assembly, and calibrating a structural zero point when the pre-jacking pressure accords with a preset pressure range;
s2, writing configuration parameters of a SENT signal and a PWM signal into a stroke sensor of an automobile pedal assembly;
s3, respectively configuring a SENT signal, a calibration point of a PWM signal and a target value in the stroke sensor, wherein the angle change trend of the PWM signal output value is set to be descending;
s4, triggering a first calibration point of a stroke sensor at a structure zero point position, triggering a second calibration point when a push rod of an automobile pedal assembly extends out of a preset distance, and generating a SENT signal, a PWM signal output value and a correlation function between the push rod stroke based on the first calibration point and the second calibration point;
s5, respectively setting zero magnetic field reference angles of the SENT signal and the PWM signal, and respectively calculating offset angle values of the SENT signal and the PWM signal output values between the zero magnetic field reference angles and the zero magnetic field actual angles;
s6, correcting a correlation function between the SENT signal and the PWM signal output value in the stroke sensor and the stroke of the push rod based on the offset angle;
wherein the actual angle of the zero magnetic field is the magnetic field angle at the zero position of the structure.
It can be understood that the HCU represents a hydraulic control unit, including a displacement sensor, an electric cylinder and a pressure sensor, in an automobile brake booster system, the hydraulic control system is used for boosting the automobile pedal assembly, in step S1, the simulated cooperation system of building the HCU and the automobile pedal assembly is specifically that the telescopic end of the electric cylinder of the HCU is abutted against the push rod of the automobile pedal assembly, so as to realize the pre-jacking action of the electric cylinder of the HCU on the push rod of the automobile pedal assembly.
In step S1, the pressure sensor of the HCU is used to obtain the preset pressure, and the preset pressure range is set, because the automobile pedal assembly has gravity, and a certain pressure is generated on the electric cylinder of the HCU in the normal working state.
In step S1, the preset pressure range is set to 0-24N, that is, when the preset pressure falls within the preset pressure range, the position is calibrated to be the structural zero point, that is, the structural coordination origin between the HCU electric cylinder and the push rod of the automobile pedal assembly.
It can be understood that in the calibration process of the travel sensor, the simulation matching system of the HCU and the automobile pedal assembly is also required to be connected to a calibration system, as shown in fig. 2, the calibration system includes an upper computer 100 connected to the hydraulic control unit 200, and a burner 400 connected to the upper computer 100 and the automobile pedal assembly 300, wherein the upper computer 100 is used for visual interaction of the burner 400 and controlling the action execution of the hydraulic control unit 200, and the burner 400 is used for configuring the travel sensor in the automobile pedal assembly.
It can be understood that in step S1, after the simulation matching system of the HCU and the automobile pedal assembly is built, the overall relative position between the HCU and the automobile pedal assembly is fixed, so that accuracy of the stroke sensor in acquiring the stroke information is ensured.
In step S2, the configuration parameters of the send signal include the frame length, the data bit number, the verification mode of the send frame, and also include the decoding mode, the communication rate, etc.; the configuration parameters of the PWM signal include frequency, duty cycle, upper and lower limits of pulse width, voltage range, etc.
In a preferred embodiment, in step S3, the calibration point of the send signal in the travel sensor is set to-18000, the first target value is set to 320, and the second target value is set to 4086; the calibration point of the PWM signal is 18000, the first target value is 16.1%, the second target value is 89.1%, and the output value angle change trend is set to decrease.
In step S4, a first calibration point of the travel sensor is triggered at the structure zero position, and a second calibration point of the travel sensor is triggered when the HCU electric cylinder pushes the vehicle pedal assembly push rod to extend 25.2 MM.
Based on the two SENT signal output values of the first calibration point and the second calibration point downstroke sensor, the push rod stroke of the automobile pedal assembly can be calculated to generate a correlation function between the SENT signal output value and the push rod stroke; the correlation function between the PWM signal output value and the push rod stroke can be calculated and generated based on the two PWM signal output values of the first calibration point, the second calibration point downstroke sensor, and the push rod stroke of the vehicle pedal assembly.
The stroke sensor can mutually check the output values of the SENT signal and the PWM signal, so that the accuracy of data acquisition is ensured.
In a preferred embodiment, in step S5, as shown in fig. 3, the function of the output value of the stroke sensor SNET and the magnetic field angle is:
Y＝65535X/360-32768；
wherein Y is the output value of the stroke sensor SNET, corresponds to the vertical axis in FIG. 3, X is the magnetic field angle, corresponds to the horizontal axis in FIG. 3, and is in the range of X (0-360 DEG) and corresponds to the range of Y (-32768-32767).
For the SENT signal output chip, the magnetic field angle increases progressively with the increase of the displacement of the push rod, so when the push rod advances relative to the zero point of the structure, the smaller the zero point magnetic field reference angle, the larger the measurable magnetic field angle range of the stroke sensor, the larger the measurable displacement range, the smaller the zero point magnetic field reference angle is, but in extreme cases, the push rod can retract relative to the zero point of the structure, and therefore the measurable displacement range of the stroke sensor needs to comprise the displacement of the push rod relative to the zero point in extreme cases, and the zero point magnetic field reference angle is preferably 35 degrees.
The SENT signal output value of the stroke sensor under the structure zero point is-24414, based on Y=65535X/360-32768, the corresponding SENT signal output value when the zero point magnetic field reference angle is set to 35 degrees is (35×65535/360-32768), and based on the formula:
offset angle value = signal output value of zero magnetic field reference angle-signal output value of zero magnetic field actual angle;
substituting the SENT signal output value of the actual angle of the zero magnetic field and the SENT signal output value of the reference angle of the zero magnetic field to obtain:
offset angle value= (35 x 65535/360-32768) - (-24414);
the offset angle value between the zero-point magnetic field actual angle and the zero-point magnetic field reference angle is-1982 when the zero-point magnetic field reference angle is configured to be 35 ° as calculated by the above equation.
It is understood that the setting value of the zero magnetic field reference angle is not limited to the above one, and represents only one preferred setting value, and the zero magnetic field reference angle can be set to other values based on the working stroke range and the accuracy requirement of the stroke sensor, for example, when the zero magnetic field reference angle is set to 50 °, the offset angle value= (50×65535/360-32768) - (-24414) is adjusted correspondingly to the above formula.
In a preferred embodiment, in step S5, as shown in fig. 4, the relationship function between the PWM output value of the stroke sensor and the magnetic field angle is:
Y＝32767-65536X/360；
wherein Y is the PWM output value of the stroke sensor, corresponds to the vertical axis in FIG. 4, X is the magnetic field angle, corresponds to the horizontal axis in FIG. 4, and is in the range of X (0-360 DEG) and corresponds to the range of Y (-32768-32767).
For the PWM signal output chip, the magnetic field angle decreases with the increase of the displacement of the push rod, so when the push rod advances relative to the zero point of the structure, the larger the zero point reference magnetic field angle is, the larger the measurable magnetic field angle range of the stroke sensor is, the larger the measurable displacement range is, so the larger the zero point magnetic field reference angle is, but in extreme cases, the push rod may retract relative to the zero point of the structure, so the measurable displacement range of the stroke sensor needs to include the displacement of the push rod which retracts relative to the zero point in extreme cases, and the zero point magnetic field reference angle is preferably 325 °.
The PWM signal output value of the stroke sensor at the structure zero point is 23515, based on y=32767-65536X/360, the PWM signal output value corresponding to the zero magnetic field reference angle set to 325 ° (32767-65536X 325/360), based on the formula:
offset angle value = signal output value of zero magnetic field reference angle-signal output value of zero magnetic field actual angle;
substituting the PWM signal output value of the actual angle of the zero magnetic field and the PWM signal output value of the reference angle of the zero magnetic field to obtain:
offset angle value= (32767-65536 x 325/360) - (23515);
the offset angle value between the zero-point magnetic field actual angle and the zero-point magnetic field reference angle is 2880 in the case where the zero-point magnetic field reference angle is configured to 325 ° by the above formula.
It is understood that the setting value of the zero-point magnetic field reference angle is not limited to the above one, and represents only one preferable setting value, and the zero-point magnetic field reference angle can be set to other values based on the working stroke range and the accuracy requirement of the stroke sensor, for example, when the zero-point magnetic field reference angle is set to 310 °, the offset angle value= (32767-65536×310/360) - (23515) is correspondingly adjusted by the above formula.
It will be appreciated that in the function of the relationship between the stroke sensor SNET, PWM output value and magnetic field angle, the range of Y (-32768-32767) represents the 16-bit binary number range in the case of complement.
It can be understood that, because the send signal output by the stroke sensor and the PWM signal should have a corresponding relationship with the stroke of the push rod, when the push rod advances by a certain displacement relative to the structural zero point, the stroke sensor can output a set value corresponding to the displacement, so as to obtain the movement stroke of the push rod according to the signal value output by the stroke sensor.
In the whole stroke range of the automobile pedal assembly, the magnetic field angle detected by the stroke sensor changes in the process of changing the position of the push rod, namely, the corresponding relation exists between the magnetic field angle and the push rod displacement, so that the corresponding relation can be established between the stroke of the push rod and the output signal as long as the corresponding relation is established between the magnetic field angle and the output signal, and the aim of calibrating the stroke sensor is to establish the corresponding relation between the output signal and the magnetic field angle.
In the embodiment of the application, in order to solve the problem of abrupt change of the magnetic field angle in the motion process of the push rod, the calibration method of the brake pedal stroke sensor is adopted to obtain a relatively stable displacement measurement range, a zero magnetic field reference angle is introduced into the stroke sensor, a corresponding relation is established between the output signal of the stroke sensor and the zero magnetic field reference angle, wherein the signal output value of the zero magnetic field reference angle = the signal output value of the zero magnetic field actual angle + the offset angle value, at the moment, although the actual magnetic field angle of the structure zero point is not fixed, the zero magnetic field reference angle can be fixed by adjusting the offset angle value, the position of the abrupt change point of the zero magnetic field reference angle is also adjusted to a relatively fixed position, the stroke sensor obtains a relatively stable displacement measurement range, and meanwhile, the size of the displacement measurement range of the stroke sensor can be adjusted by adjusting the zero magnetic field reference angle.
In a preferred embodiment, in step S6, after the offset angle values of the send signal and the PWM signal are obtained, the burner 500 can correct the correlation function between the output values of the send signal and the PWM signal and the stroke of the push rod and write the correlation function into the control chip of the stroke sensor.
In a preferred embodiment, the method further comprises:
s7, acquiring a SENT/PWM signal output value of the stroke sensor under a structure zero point when the push rod of the automobile pedal assembly is in a complete release state;
s8, comparing the CAN signal packaged by the SENT/PWM signal output value corresponding to the original signal at the structure zero point with the upper limit value/lower limit value of the corresponding zero point standard to form a judging result.
It is understood that in step S8, the zero standard upper/lower limit value corresponding to the send/PWM signal output value at the structure zero point is shown in the following table 1:
table 1 Structure zero standard upper/lower limit schematic table
In a preferred embodiment, in step S8, when the CAN signal of the package corresponding to the original signal at the structure zero point output value is compared with the corresponding zero point standard upper/lower limit value, the expected error range is not greater than 0.5%, that is, when the error between the CAN signal corresponding to the structure zero point output value and the corresponding zero point standard upper/lower limit value is not greater than 0.5%, the CAN signal is judged to be qualified, and otherwise, the CAN signal is judged to be unqualified.
It will be appreciated that recalibration is performed for an unacceptable travel sensor, and that a total number of calibrations exceeding three is marked as a problem.
In a preferred embodiment, the method further comprises:
s9, the HCU electric cylinder moves the push rod of the automobile pedal assembly from the structure zero position by a preset stroke at a preset speed, and a SENT/PWM signal output value of the stroke sensor in the push rod moving process is obtained;
s10, respectively generating signal curves based on CAN signals of which the SENT/PWM signal output values correspond to original signal packages in the push rod moving process, and comparing the signal curves corresponding to the SENT/PWM signal output values with corresponding standard upper/lower limit curves to form a judging result;
when the push rod of the automobile pedal assembly moves to the preset stroke end point, the thrust of the HCU electric cylinder to the push rod of the automobile pedal assembly is not more than the rated top pressure.
It is understood that the stroke sensor determined to be qualified in step S8 further performs the signal test of steps S9 and S10.
In a preferred embodiment, in step S9, the HCU electric cylinder pushes the push rod of the automobile pedal assembly at a speed of 1.2mm/S until the push rod moves 30mm relative to the structural zero point;
if the thrust of the HCU electric cylinder to the push rod reaches 250N in the process that the push rod moves 30mm relative to the structural zero point, the position of 250N is taken as the preset stroke end of the push rod.
In a preferred embodiment, in step S10, for the send signal output value, the corresponding standard upper limit curve calculation function is:
Y＝(X/25.2*3766+320)*(1+2％)；
wherein Y is the standard upper limit value of the SENT signal, X is the displacement (mm) of the HCU electric cylinder relative to the zero point of the structure and is larger than zero.
In a preferred embodiment, in step S10, for the send signal output value, the corresponding standard lower limit curve calculation function is:
Y＝(X/25.2*3766+320)*(1-2％)；
wherein Y is the standard lower limit value of the SENT signal, X is the displacement (mm) of the HCU electric cylinder relative to the zero point of the structure and is larger than zero.
In a preferred embodiment, in step S10, for the PWM signal output value, the corresponding standard upper limit curve calculation function is:
Y＝(X/25.2*73+16.1)*(1+2％)；
y is the standard upper limit value of the PWM signal, and X is the displacement (mm) of the HCU electric cylinder relative to the zero point of the structure and is larger than zero.
In a preferred embodiment, in step S10, for the PWM signal output value, the corresponding standard lower limit curve calculation function is:
Y＝(X/25.2*73+16.1)*(1-2％)；
y is the standard lower limit value of the PWM signal, and X is the displacement (mm) of the HCU electric cylinder relative to the structural zero point and is larger than zero.
In a preferred embodiment, in step S10, if the signal curve corresponding to the output value of the send/PWM signal does not exceed the corresponding standard upper/lower limit curve during the movement of the push rod, the signal curve is judged to be qualified, otherwise, the signal curve is judged to be unqualified.
It will be appreciated that recalibration is performed for an unacceptable travel sensor, and that a total number of calibrations exceeding three is marked as a problem.
According to the embodiment of the application, by adopting the calibration method of the brake pedal stroke sensor, the upper limit and the lower limit of the SENT/PWM signal value output by the stroke sensor in the structure zero point and push rod moving process are compared so as to ensure the measurement precision of the stroke sensor, and the recalibration can be performed on the unqualified stroke sensor, so that the overall calibration quality of the stroke sensor is improved.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, 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, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. Furthermore, it should be noted that the scope of the methods and apparatus in the embodiments of the present application is not limited to performing the functions in the order shown or discussed, but may also include performing the functions in a substantially simultaneous manner or in an opposite order depending on the functions involved, e.g., the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.
The embodiments of the present application have been described above with reference to the accompanying drawings, but the present application is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those having ordinary skill in the art without departing from the spirit of the present application and the scope of the claims, which are to be protected by the present application.
Claims (10)
1. A method for calibrating a brake pedal travel sensor, comprising:
building a simulation matching system of the HCU and the automobile pedal assembly, and calibrating a structural zero point when the pre-jacking pressure between the HCU electric cylinder and the push rod of the automobile pedal assembly accords with a preset pressure range;
writing configuration parameters of a SENT signal and a PWM signal into a stroke sensor of an automobile pedal assembly;
respectively configuring a SENT signal, a calibration point of a PWM signal and a target value in the stroke sensor, wherein the angle change trend of the PWM signal output value is set to be descending;
performing two-point calibration of the stroke sensor and generating a correlation function between the SENT signal, the PWM signal output value and the push rod stroke;
setting the zero magnetic field reference angles of the SENT signal and the PWM signal respectively, and calculating offset angle values of the SENT signal and the PWM signal output values between the zero magnetic field reference angles and the zero magnetic field actual angles respectively;
correcting a correlation function between a SENT signal and a PWM signal output value in the stroke sensor and the stroke of the push rod based on the offset angle;
wherein the actual angle of the zero magnetic field is the magnetic field angle at the zero position of the structure.
2. The method for calibrating a brake pedal stroke sensor according to claim 1, wherein the configuration parameters of the send signal and the PWM signal are written, and the configuration parameters of the send signal include a frame length, a data bit number, a verification mode, a decoding mode, and a communication rate of the send frame;
the configuration parameters of the PWM signal comprise frequency, duty ratio, upper and lower limits of pulse width and voltage range.
3. The method of calibrating a brake pedal travel sensor according to claim 1, wherein said performing a two-point calibration of a travel sensor comprises:
triggering a first calibration point of a travel sensor at a structure zero point position, and triggering a second calibration point when a push rod of an automobile pedal assembly extends out of a preset distance;
two SENT signal output values and two PWM signal output values of the first calibration point and the second calibration point downstroke sensor are obtained.
4. The method for calibrating a brake pedal travel sensor according to claim 1, wherein the method for calculating the offset angle value is as follows:
offset angle value = signal output value of zero magnetic field reference angle-signal output value of zero magnetic field actual angle;
the signal output value of the actual angle of the zero magnetic field is the SENT signal/PWM signal output value of the structural zero downstroke sensor.
5. The method for calibrating a brake pedal stroke sensor according to claim 4, wherein for the send signal, the method for obtaining the signal output value of the zero magnetic field reference angle is as follows:
Y＝65535X/360-32768；
wherein X is the zero magnetic field reference angle of the SENT signal, and Y is the output value of the SENT signal under the zero magnetic field reference angle.
6. The method for calibrating a brake pedal stroke sensor according to claim 4, wherein for the PWM signal, the method for obtaining the signal output value of the zero magnetic field reference angle is as follows:
Y＝32767-65535X/360；
wherein X is the zero magnetic field reference angle of the PWM signal, and Y is the output value of the PWM signal under the zero magnetic field reference angle.
7. The method according to any one of claims 4 to 6, wherein the zero magnetic field reference angle of the send signal is set to 35 ° and the zero magnetic field reference angle of the PWM signal is set to 325 °.
8. The method for calibrating a brake pedal stroke sensor according to claim 1, wherein the correcting the correlation function between the send signal, the PWM signal output value and the push rod stroke in the stroke sensor further comprises:
acquiring a SENT/PWM signal output value of a stroke sensor under a structure zero point when a push rod of an automobile pedal assembly is in a complete release state;
comparing the CAN signal packaged by the SENT/PWM signal output value corresponding to the original signal at the structure zero point with the upper limit value/lower limit value of the corresponding zero point standard to form a judging result;
the error range between the SENT/PWM signal output value at the zero point of the structure, corresponding to the CAN signal packaged by the original signal, and the upper/lower limit value of the corresponding zero point standard is set to be not more than 0.5%.
9. The method for calibrating a brake pedal travel sensor according to claim 8, wherein the forming a determination result further comprises:
the HCU electric cylinder moves the push rod of the automobile pedal assembly from the structure zero position by a preset stroke at a preset speed, and a SENT/PWM signal output value of the stroke sensor in the push rod moving process is obtained;
generating signal curves respectively based on CAN signals of the SENT/PWM signal output values corresponding to the original signal packages in the push rod moving process, and comparing the signal curves corresponding to the SENT/PWM signal output values with corresponding standard upper/lower limit curves to form a judging result;
when the push rod of the automobile pedal assembly moves to the preset stroke end point, the thrust of the HCU electric cylinder to the push rod of the automobile pedal assembly is not more than the rated top pressure.
10. The method for calibrating a brake pedal stroke sensor according to claim 9, wherein the standard upper/lower limit curve calculation function corresponding to the send signal output value is:
Y 1 ＝(X/25.2*3766+320)*(1±2％)；
wherein Y is 1 X is the displacement (mm) of the HCU electric cylinder relative to the structural zero point and is larger than zero;
the standard upper/lower limit curve calculation function corresponding to the PWM signal output value is as follows:
Y 2 ＝(X/25.2*73+16.1)*(1±2％)；
wherein Y is 2 And X is the displacement (mm) of the HCU electric cylinder relative to the structural zero point and is larger than zero.
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