CN117740226A - Device and method for measuring vertical force of tire - Google Patents
Device and method for measuring vertical force of tire Download PDFInfo
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- CN117740226A CN117740226A CN202410038879.2A CN202410038879A CN117740226A CN 117740226 A CN117740226 A CN 117740226A CN 202410038879 A CN202410038879 A CN 202410038879A CN 117740226 A CN117740226 A CN 117740226A
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- 238000004364 calculation method Methods 0.000 claims description 17
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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
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Abstract
The invention discloses a device and a method for measuring vertical force of a tire, wherein the device comprises: the system comprises a strain sensing module, a data transmission module and a control module; the strain sensing module and the data transmission module are both arranged on the inner side of the tire to be measured; the strain sensing module is connected with the data transmission module, and the data transmission module is connected with the control module; the strain sensing module comprises a strain sensor, wherein the strain sensor comprises an upper substrate made of rubber, a lower substrate made of rubber, a sensitive layer and a sensor terminal; the sensitive layer is arranged between the upper substrate and the lower substrate, and the sensor terminals are arranged at two sides of the strain sensor; the strain sensing module is used for acquiring the strain waveform of the tire to be measured and transmitting the strain waveform to the data transmission module; the data transmission module is used for transmitting the strain waveform to the control module; the control module is used for measuring the vertical force of the tire according to the strain waveform to obtain the vertical force of the tire. The invention can effectively improve the accuracy of the measurement of the vertical force of the tire.
Description
Technical Field
The invention relates to the technical field of vehicle engineering, in particular to a tire vertical force measuring device and a measuring method.
Background
The real-time measurement of the vertical force of the tire has great significance, and by measuring the vertical force of the tire, the tire can be truly recorded, the service life of the tire is prolonged according to the service condition, and the smoothness and the steering stability of vehicle control can be improved. The intelligent tire is generally provided with a sensor system inside the tire, so that the real-time acquisition and transmission of signals such as the ground strain and the acceleration of the tire are realized, and the stress of the tire is monitored.
The conventional tire vertical force measuring device is usually provided with an acceleration sensor outside a tire, directly solves the information such as grounding time and the like based on an acceleration signal, and further calculates the vertical force of the tire, but because the accuracy of the acceleration signal is easily influenced by external environment, larger calculation errors are easy to occur, and the tire vertical force is difficult to accurately measure.
Disclosure of Invention
The invention provides a device and a method for measuring vertical force of a tire, which are used for solving the technical problems that the accuracy of an acceleration signal obtained by an acceleration sensor arranged on the outer side of the tire in the conventional device for measuring vertical force of the tire is easily influenced by external environment, and larger calculation errors are easily caused, so that the vertical force of the tire is difficult to accurately measure.
The invention provides a tire vertical force measuring device, comprising:
the system comprises a strain sensing module, a data transmission module and a control module;
the strain sensing module and the data transmission module are both arranged on the inner side of the tire to be measured;
the strain sensing module is connected with the data transmission module, and the data transmission module is connected with the control module;
the strain sensing module comprises a strain sensor, wherein the strain sensor comprises an upper substrate made of rubber, a lower substrate made of rubber, a sensitive layer and a sensor terminal;
the sensitive layer is arranged between the upper substrate and the lower substrate, and the sensor terminals are arranged on two sides of the strain sensor;
the data transmission module is provided with a rubber sleeve shell;
the strain sensing module is used for acquiring a strain waveform of the tire to be measured and transmitting the strain waveform to the data transmission module;
the data transmission module is used for receiving the strain waveform and transmitting the strain waveform to the control module;
and the control module is used for measuring the tire vertical force according to the strain waveform to obtain the tire vertical force of the tire to be measured.
The invention also provides a tire vertical force measuring method, which is suitable for the tire vertical force measuring device, and comprises the following steps:
according to the strain waveform obtained by the strain sensing module, obtaining the grounding time and the rotation period time of the tire to be measured, and calculating according to the grounding time and the rotation period time to obtain the grounding angle of the tire to be measured;
according to the grounding angle and the free rolling radius of the tire to be measured, calculating to obtain the length of the grounding trace of the tire to be measured;
calculating the speed of the tire to be measured according to the rotation period time, the diameter of the tire to be measured and the sampling frequency of the strain sensor;
constructing and obtaining a first dynamics model based on the ground contact patch length, the free rolling radius, the tire vertical force and the tire vertical rigidity;
and solving to obtain the tire vertical force of the tire to be measured according to the speed of the tire to be measured and the first dynamics model.
Further, according to the strain waveform obtained by the strain sensing module, obtaining the grounding time and the rotation period time of the tire to be measured includes:
according to the strain waveform obtained by the strain sensing module, obtaining a plurality of data points of the strain sensor, and respectively carrying out first-order derivation, second-order derivation and third-order derivation on each data point;
when the multiplication of the second derivative of the (n+2) th data point and the second derivative of the previous point or the next point is smaller than or equal to 0 and the third derivative of the current data point is larger than 0, the current data point is put into a first-order guided wave valley candidate data point set, and n is the 1 st data point;
if the current data point is the last data point, clearing points with first order conduction less than a set threshold value in the first order guided wave valley candidate data point set;
starting from a first data point of remaining data points in the first-order guided wave valley candidate data point set, establishing a set width window, and extracting a data point with the minimum first order guide into the first-order guided wave valley data point set according to the set width window until no remaining data points exist in the first-order guided wave valley candidate data point set;
setting a set width window by taking each data point in the first-order guided wave valley data point set as a right edge, and extracting a data point value with the largest first-order guided wave peak data point value from the first-order guided wave valley data point set according to the set width window;
setting a current data point as a starting point and a next data point as b, if a is more than or equal to b, giving b as a next data point, if b is more than or equal to b, giving c as a last data point of a when b is more than a, if c=a, giving c as a last data point when c is more than a, taking a as a rear trough, traversing all data points in the first-order guided wave trough data point set, and obtaining all rear troughs in the first-order to trough data point set;
setting a current data point as a starting point and a previous data point as b, if a is more than or equal to b, giving b as a previous data point, if b is more than or equal to b, giving c as a next data point of a when b is more than a, if c=a, giving c as a next data point until c is more than a, traversing all data points in the first-order guided wave peak data point set by taking a as a money trough, and acquiring all previous data points in the first-order to peak data point set;
and determining the grounding time of the tire to be measured according to the front trough and the rear trough.
Further, the calculating, according to the grounding time and the rotation period time, the grounding angle of the tire to be measured includes:
recording the ratio of the ground contact time to the rotation period time as the ground contact duty ratio of the tire;
multiplying the grounding duty ratio by the angle corresponding to the rotation period time to obtain the grounding angle of the tire to be measured, wherein the angle corresponding to the rotation period time is 360 degrees.
Further, the calculating, according to the contact angle and the free rolling radius of the tire to be measured, the length of the contact patch of the tire to be measured includes:
the footprint length of the tire to be measured is calculated according to the following formula:
l＝R 0 *sinθ
C l ＝2l
wherein, the grounding trace is half-long and R 0 Is free rolling radius, theta is half of the grounding angle, C l Is the length of the ground trace.
Further, according to the rotation period time, the diameter of the tire to be measured and the sampling frequency of the strain sensor, calculating to obtain the speed of the tire to be measured, including:
the speed of the tire to be measured is calculated according to the following formula:
wherein v is the speed of the tire to be measured, D is the diameter of the tire to be measured, f is the sampling frequency of the strain sensor, and L is the rotation cycle time of the tire to be measured.
Further, the first dynamics model is:
wherein C is l For ground trace length, R 0 Is of free radius F z For vertical force, C z For vertical stiffness, k 1 ，k 2 The number of times to be fitted.
Further, the solving to obtain the tire vertical force of the tire to be measured according to the speed of the tire to be measured and the first dynamics model includes:
approximating the first kinetic model as a second kinetic model as follows:
wherein P is tire pressure;
and (3) substituting the speed of the tire into the second dynamic model for correction to obtain a third dynamic model as follows:
and solving the third dynamic model to obtain the tire vertical force of the tire to be measured.
The invention also provides a device for measuring the vertical force of a tire, which comprises:
the grounding angle calculation module is used for acquiring the grounding time and the rotation period time of the tire to be measured according to the strain waveform acquired by the strain sensing module and calculating the grounding angle of the tire to be measured according to the grounding time and the rotation period time;
the grounding mark length calculation module is used for calculating the grounding mark length of the tire to be measured according to the grounding angle and the free rolling radius of the tire to be measured;
the tire speed calculation module is used for calculating the speed of the tire to be measured according to the rotation period time, the diameter of the tire to be measured and the sampling frequency of the strain sensor;
the dynamics model construction module is used for constructing and obtaining a first dynamics model based on the length of the grounding trace, the free rolling radius, the vertical tire force and the vertical tire stiffness;
and the tire vertical force solving module is used for solving and obtaining the tire vertical force of the tire to be measured according to the speed of the tire to be measured and the first dynamics model.
The invention also provides a storage medium comprising a stored computer program, wherein the computer program when run controls a device in which the storage medium is located to perform a method of measuring tire vertical force as described above.
According to the invention, the strain sensor is arranged on the inner side of the tire, the upper substrate and the lower substrate made of rubber materials in the strain sensor can enable the strain sensor to synchronously strain with the tire, so that the strain condition of the tire can be accurately reflected according to the strain waveform of the strain sensor, the grounding area waveform of the strain waveform output by the strain sensor is obvious, the grounding time and the rotation period time of the tire can be accurately calculated according to the data points of the waveform of the street area, and the tire vertical force can be accurately calculated according to the grounding time and the rotation period time of the tire, and the accuracy of the tire vertical force measurement can be effectively improved.
Drawings
FIG. 1 is a schematic view of a tire vertical force measurement apparatus according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a sensor module according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of an acquisition circuit of a strain sensor according to an embodiment of the present invention;
FIG. 4 is a graph showing the comparison of strain waveforms of a strain sensor and an acceleration sensor during the grounding process of a tire according to an embodiment of the present invention
FIG. 5 is a schematic diagram of a waveform of an output of a strain sensor according to an embodiment of the present invention;
FIG. 6 is a flow chart of a method for measuring tire vertical force according to an embodiment of the present invention;
fig. 7 is a schematic flowchart of a ground point identification algorithm according to an embodiment of the present invention;
fig. 8 is another schematic structural view of a tire vertical force measuring device according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.
In the description of the present application, it should be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or an implicit indication of the number of technical features being indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present application, unless otherwise indicated, the meaning of "a plurality" is two or more.
In the description of the present application, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art in a specific context.
Referring to fig. 1, one embodiment of the present invention provides a tire vertical force measuring apparatus, comprising:
the device comprises a strain sensing module 1, a data transmission module 2 and a control module 3;
the strain sensing module 1 and the data transmission module 2 are arranged on the inner side of the tyre 5 to be measured;
in the embodiment of the invention, the strain sensing module 1 is attached to the inner side of the tire, so that the modulus of the strain sensing module 1 can be similar to that of the inner tire surface material of the tire, and the strain degree of the tire can be accurately detected, so that an accurate strain waveform can be output.
The strain sensing module 1 is connected with the data transmission module 2, and the data transmission module 2 is connected with the control module 3;
in the embodiment of the present invention, the strain sensing module 1 may be connected to the data transmission module 2 through a wire 4.
Referring to fig. 2, the strain sensing module 1 includes a strain sensor, wherein the strain sensor includes a rubber upper substrate, a rubber lower substrate, a sensitive layer and sensor terminals;
in the embodiment of the invention, the upper substrate and the lower substrate made of rubber can enable the strain sensor and the tire to synchronously strain, so that the strain condition of the tire can be accurately reflected according to the strain waveform of the strain sensor.
The sensitive layer is arranged between the upper substrate and the lower substrate, and the sensor terminals are arranged at two sides of the strain sensor;
the data transmission module 2 is provided with a rubber sleeve shell 21;
in the embodiment of the present invention, the rubber sleeve housing 21 is mainly used for carrying the hardware module and is adhered and fixed with the tire. The tire vertical force measuring device can also comprise a battery module, wherein the battery module is mainly used for supplying power to the tire vertical force measuring device and can be used as a standard-class button battery.
In the embodiment of the invention, the data transmission module 2 comprises a constant voltage dividing resistor, an ADC module, an air pressure sensor, a Bluetooth module and an antenna.
The strain sensing module 1 is used for acquiring a strain waveform of a tire 5 to be measured and transmitting the strain waveform to the data transmission module 2;
in the embodiment of the present invention, an acquisition circuit is disposed in the strain sensor to obtain a strain waveform of the tire 5 to be measured, refer to fig. 3, and a schematic structural diagram of an acquisition circuit built in the strain sensor is provided in the embodiment of the present invention.
The data transmission module 2 is used for receiving the strain waveform and transmitting the strain waveform to the control module 3;
in the embodiment of the present invention, the data transmission module 2 transmits waveform data to the control module 3 through a bluetooth wireless transmission signal.
The control module 3 is used for measuring the tire vertical force according to the strain waveform to obtain the tire vertical force of the tire 5 to be measured.
Referring to fig. 4, a strain waveform comparison chart of a tire grounding process strain sensor and an acceleration sensor according to an embodiment of the present invention is shown.
Referring to fig. 5, in the embodiment of the present invention, the strain waveform output by the strain sensor can accurately reflect the strain situation of the tire, different waveforms of the tire in the entering area, the grounding area and the exiting area can be identified from the strain waveform, the strain waveform is composed of a plurality of strain data points, and the tire vertical force of the tire 5 to be measured can be calculated based on the data points of the strain waveform.
According to the embodiment of the invention, the strain sensor is arranged on the inner side of the tire, the grounding area waveform of the strain waveform output by the strain sensor is obvious, the grounding time and the rotation period time of the tire can be accurately calculated according to the data points of the grounding area waveform, the tire vertical force can be accurately calculated according to the grounding time and the rotation period time of the tire, and the accuracy of measuring the tire vertical force can be effectively improved.
Referring to fig. 6, the present invention provides a method for measuring a vertical force of a tire, which is applicable to the apparatus for measuring a vertical force of a tire, and includes:
s1, acquiring the grounding time and the rotation period time of a tire to be measured according to a strain waveform acquired by a strain sensing module, and calculating the grounding angle of the tire to be measured according to the grounding time and the rotation period time;
in the embodiment of the invention, the calibration test of the tire refers to a uniform rolling test under different loads, tire pressures and speeds through a bench to acquire corresponding data. When the tire to be measured is calibrated, the strain sensor is arranged in the tire to be measured, and the ground deformation of the tire is monitored through the strain sensor.
The strain sensor outputs a waveform corresponding to the rotation output of the tire, and the grounding time and the rotation period time of the tire to be measured can be obtained according to the waveform of the sensor output.
S2, calculating to obtain the length of the grounding trace of the tire to be measured according to the grounding angle and the free rolling radius of the tire to be measured;
in the embodiment of the invention, the free rolling radius of the tire can be obtained by a direct measurement mode, and the ground contact patch length of the tire can be obtained by calculating according to the ground contact angle and the free rolling radius by utilizing a trigonometric function relation.
S3, calculating to obtain the speed of the tire to be measured according to the rotation period time, the diameter of the tire to be measured and the sampling frequency of the strain sensor;
s4, constructing and obtaining a first dynamics model based on the length of the grounding trace, the free rolling radius, the vertical force of the tire and the vertical rigidity of the tire;
and S5, solving to obtain the tire vertical force of the tire to be measured according to the speed of the tire to be measured and the first dynamics model.
According to the embodiment of the invention, the tire is subjected to calibration test to obtain the strain waveform output by the strain sensor according to the strain condition of the tire, the ground trace length and the speed of the tire are obtained based on the strain waveform, the first dynamics model is constructed based on the ground trace length, the free rolling radius, the tire vertical force and the tire vertical rigidity, the tire vertical force of the tire to be measured is obtained by solving the first dynamics model according to the speed of the tire to be measured, the ground point can be accurately identified according to the data in the tire calibration test, the ground time is determined, and the ground point is not influenced by external conditions such as the tire speed, so that the calculation error can be effectively reduced, and the accuracy of the tire vertical force measurement can be effectively improved.
In the embodiment of the invention, the strain sensor is attached to the inside of the tire, has similar modulus to the inner tube material of the tire, and can detect the strain degree of the tire in situ, so that the strain waveform output by the sensor when the tire is grounded is clear and obvious, the grounding point can be accurately identified under the conditions of high speed and low speed, the influence of the running speed of the tire is avoided, and the accuracy of the measurement of the vertical force of the tire can be effectively improved.
In one embodiment, S1, obtaining a grounding time and a rotation cycle time of a tire to be measured according to a strain waveform obtained by a strain sensing module, includes:
s11, acquiring a plurality of data points of a strain sensor according to the strain waveform acquired by the strain sensing module, and respectively carrying out first-order derivation, second-order derivation and third-order derivation on each data point;
s12, when the multiplication of the second derivative of the (n+2) th data point and the second derivative of the previous point or the next point is smaller than or equal to 0 and the third derivative of the current data point is larger than 0, the current data point is put into the first-order guided wave valley candidate data point set, and n is the 1 st data point;
s13, if the current data point is the last data point, clearing the point of which the first order guide in the first order guided wave valley candidate data point set is smaller than a set threshold value; if the current data point is not the last data point, the step S12 is executed for the next data point until the last data point is executed.
S14, starting from a first data point of remaining data points in the first-order guided wave valley candidate data point set, establishing a set width window, and extracting the data point with the minimum first order guide into the first-order guided wave valley data point set according to the set width window until no remaining data point exists in the first-order guided wave valley candidate data point set;
s15, taking each data point in the first-order guided wave valley data point set as the right edge, establishing a set width window, and extracting a data point value with the maximum first-order guide value from the first-order guided wave valley data point set from the first-order guided wave peak data point set according to the set width window;
s16, setting a current data point as a starting point and a next data point as b by taking a data point in a first-order guided wave valley data point set as a starting point, if a is larger than or equal to b, giving b as a next data point, if b is larger than a, giving c as a last data point of a, if c=a, giving c as a last data point, until c is larger than a, taking a as a rear trough, traversing all data points in the first-order guided wave valley data point set, and obtaining all rear troughs in the first-order to trough data point set;
s17, setting a current data point as a starting point and a previous data point as b, if a is larger than or equal to b, giving b as a previous data point, if b is larger than or equal to a, giving c as a next data point of a when b is larger than a, if c=a, giving c as a next data point when c is larger than a, taking a as a money trough, traversing all data points in the first-order guided wave peak data point set, and obtaining all front troughs from the first order to the peak data point set;
s18, determining the grounding time of the tire to be measured according to the front trough and the rear trough.
Fig. 7 is a schematic flow chart of a ground point recognition algorithm according to an embodiment of the invention.
In one embodiment, step S1, calculating the ground contact angle of the tire to be measured according to the ground contact time and the rotation cycle time includes:
s101, marking the ratio of the grounding time to the rotation period time as the grounding duty ratio of the tire;
s102, multiplying the grounding duty ratio by an angle corresponding to the rotation period time to obtain the grounding angle of the tire to be measured, wherein the angle corresponding to the rotation period time is 360 degrees.
In the embodiment of the invention, the ground contact ratio of the tire can be determined according to the ground contact time and the rotation period time, so that the ground contact angle of the tire can be further determined.
In one embodiment, step S2, calculating the length of the footprint of the tire to be measured according to the ground contact angle and the free rolling radius of the tire to be measured, includes:
the footprint length of the tire to be measured is calculated according to the following formula:
l＝R 0 *sinθ
C l ＝2l
wherein, the grounding trace is half-long and R 0 Is free rolling radius, theta is half of the grounding angle, C l Is the length of the ground trace.
In one embodiment, step S3, calculating the speed of the tire to be measured according to the rotation cycle time, the diameter of the tire to be measured and the sampling frequency of the strain sensor, includes:
the speed of the tire to be measured is calculated according to the following formula:
wherein v is the speed of the tire to be measured, D is the diameter of the tire to be measured, f is the sampling frequency of the strain sensor, and L is the rotation cycle time of the tire to be measured.
In one embodiment, the first kinetic model is:
wherein C is l For ground trace length, R 0 Is of free radius F z For vertical force, C z For vertical stiffness, k 1 ，k 2 The number of times to be fitted.
In the embodiment of the invention, the load, the Tire pressure, the speed, the free rolling radius and the length of the grounding trace can be substituted into the Swift Tire dynamic model to output a calibration relation between the length of the grounding trace and the load, wherein the relation comprises factors influencing the length of the grounding trace such as the speed, the Tire pressure and the like.
In one embodiment, step S5, solving to obtain the tire vertical force of the tire to be measured according to the speed of the tire to be measured and the first dynamics model, includes:
s51, approximating the first dynamics model into a second dynamics model as follows:
wherein P is tire pressure;
in the embodiment of the invention, since the vertical rigidity of the tire is mainly determined by the tire pressure, the first dynamic model can be approximated to the second dynamic model.
S52, correcting the speed of the tire by replacing the speed of the tire with the second dynamic model to obtain a third dynamic model as follows:
in the embodiment of the invention, the length of the footprint is changed along with the change of the speed, and a corrected third dynamic model can be obtained by introducing the speed of the tire into the second dynamic model.
And S53, solving the third dynamic model to obtain the tire vertical force of the tire to be measured.
In the embodiment of the invention, the obtained parameters or known parameters are substituted into a third dynamic model, and the tire vertical force of the tire to be measured is obtained by solving.
In the embodiment of the invention, parameters such as the length of the grounding trace, the speed of the tire, the tire pressure, the free rolling radius of the tire, the vertical rigidity, the parameters to be fitted and the like are substituted into the third dynamic model, and the tire vertical force of the tire to be measured is accurately obtained by solving.
The embodiment of the invention has the following beneficial effects:
according to the embodiment of the invention, the ground trace length and the speed of the tire are calculated based on the data of the calibration test of the tire, the first dynamics model is constructed based on the ground trace length, the free rolling radius, the tire vertical force and the tire vertical rigidity, the tire vertical force of the tire to be measured is obtained by solving the first dynamics model according to the speed of the tire to be measured, the ground point can be accurately identified according to the data of the calibration test of the tire, the ground time is determined, and the influence of external conditions such as the tire speed is avoided, so that the calculation error can be effectively reduced, and the accuracy of the measurement of the tire vertical force can be effectively improved.
Furthermore, in the embodiment of the invention, the influence factors of the tire pressure are considered, the first dynamics model is approximated to the second dynamics model, the speed of the tire is replaced by the second dynamics model to be corrected to obtain the third dynamics model, and various factors influencing the measurement of the vertical force of the tire are fully considered, so that the accuracy of the measurement of the vertical force of the tire can be further improved.
Referring to fig. 6, based on the same inventive concept as the above embodiment, the present invention further provides a tire vertical force measuring device, including:
the grounding angle calculation module 10 is configured to obtain a grounding time and a rotation period time of the tire to be measured according to the strain waveform obtained by the strain sensing module, and calculate the grounding angle of the tire to be measured according to the grounding time and the rotation period time;
the footprint length calculation module 20 is configured to calculate a footprint length of the tire to be measured according to the ground contact angle and the free rolling radius of the tire to be measured;
a tire speed calculation module 30 for calculating the speed of the tire to be measured according to the rotation cycle time, the diameter of the tire to be measured and the sampling frequency of the strain sensor;
a dynamics model construction module 40 for constructing a first dynamics model based on the footprint length, the free rolling radius, the tire vertical force and the tire vertical stiffness;
the tire vertical force solving module 50 is configured to solve to obtain a tire vertical force of the tire to be measured according to the speed of the tire to be measured and the first dynamics model.
In one embodiment, the ground angle calculation module 10 is further configured to:
according to the strain waveform obtained by the strain sensing module, obtaining a plurality of data points of the strain sensor, and respectively carrying out first-order derivation, second-order derivation and third-order derivation on each data point;
when the second derivative of the (n+2) th data point is multiplied by the second derivative of the previous point or the next point to be less than or equal to 0 and the third derivative of the current data point is more than 0, the current data point is put into the first-order guided wave valley candidate data point set, and n is the 1 st data point;
if the current data point is the last data point, clearing the point of which the first order guide in the first order guided wave valley candidate data point set is smaller than a set threshold value;
starting from a first data point of remaining data points in the first-order guided wave valley candidate data point set, establishing a set width window, and extracting the data point with the minimum first order guide into the first-order guided wave valley data point set according to the set width window until no remaining data points exist in the first-order guided wave valley candidate data point set;
taking each data point in the first-order guided wave valley data point set as the right edge, establishing a set width window, and extracting a data point value with the maximum first-order guide value from the first-order guided wave valley data point set into a first-order guided wave peak data point set according to the set width window;
setting a current data point as a starting point and a next data point as b, if a is more than or equal to b, giving b as a next data point, if b is more than or equal to b, giving c as a last data point of a when b is more than a, if c=a, giving c as a last data point when c is more than a, taking a as a rear trough, traversing all data points in the first-order guided wave trough data point set, and obtaining all rear troughs in the first-order to trough data point set;
setting a current data point as a starting point and a previous data point as b, if a is more than or equal to b, giving b as a previous data point, if b is more than or equal to b, giving c as a next data point of a when b is more than a, if c=a, giving c as a next data point until c is more than a, taking a as a money trough, traversing all data points in the first-order guided wave peak data point set, and obtaining all previous troughs in the first-order to peak data point set;
and determining the grounding time of the tire to be measured according to the front trough and the rear trough.
In one embodiment, the ground angle calculation module 10 is further configured to:
the ratio of the ground contact time to the rotation period time is recorded as the ground contact duty ratio of the tire;
multiplying the grounding duty ratio by the angle corresponding to the rotation period time to obtain the grounding angle of the tire to be measured, wherein the angle corresponding to the rotation period time is 360 degrees.
In one embodiment, the footprint length calculation module 20 is further configured to:
the footprint length of the tire to be measured is calculated according to the following formula:
l＝R 0 *sinθ
C l ＝2l
wherein, the grounding trace is half-long and R 0 Is free rolling radius, theta is half of the grounding angle, C l Is the length of the ground trace.
In one embodiment, the tire speed calculation module 30 is further configured to:
the speed of the tire to be measured is calculated according to the following formula:
wherein v is the speed of the tire to be measured, D is the diameter of the tire to be measured, f is the sampling frequency of the strain sensor, and L is the rotation cycle time of the tire to be measured.
In one embodiment, the first kinetic model is:
wherein C is l For ground trace length, R 0 Is of free radius F z For vertical force, C z For vertical stiffness, k 1 ，k 2 The number of times to be fitted.
In one embodiment, the tire vertical force solution module 50 is further configured to:
approximating the first kinetic model as a second kinetic model as follows:
wherein P is tire pressure;
and (3) substituting the speed of the tire into the second dynamic model for correction to obtain a third dynamic model as follows:
and solving the third dynamic model to obtain the tire vertical force of the tire to be measured.
The invention also provides a storage medium comprising a stored computer program, wherein the computer program when run controls a device in which the storage medium is located to perform a method for measuring a tire vertical force as described above.
The foregoing is a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention and are intended to be comprehended within the scope of the present invention.
Claims (10)
1. A tire vertical force measurement apparatus, comprising:
the system comprises a strain sensing module, a data transmission module and a control module;
the strain sensing module and the data transmission module are both arranged on the inner side of the tire to be measured;
the strain sensing module is connected with the data transmission module, and the data transmission module is connected with the control module;
the strain sensing module comprises a strain sensor, wherein the strain sensor comprises an upper substrate made of rubber, a lower substrate made of rubber, a sensitive layer and a sensor terminal;
the sensitive layer is arranged between the upper substrate and the lower substrate, and the sensor terminals are arranged on two sides of the strain sensor;
the data transmission module is provided with a rubber sleeve shell;
the strain sensing module is used for acquiring a strain waveform of the tire to be measured and transmitting the strain waveform to the data transmission module;
the data transmission module is used for receiving the strain waveform and transmitting the strain waveform to the control module;
and the control module is used for measuring the tire vertical force according to the strain waveform to obtain the tire vertical force of the tire to be measured.
2. A method of measuring tire vertical force, adapted for use in the tire vertical force measuring apparatus of claim 1, comprising:
according to the strain waveform obtained by the strain sensing module, obtaining the grounding time and the rotation period time of the tire to be measured, and calculating according to the grounding time and the rotation period time to obtain the grounding angle of the tire to be measured;
according to the grounding angle and the free rolling radius of the tire to be measured, calculating to obtain the length of the grounding trace of the tire to be measured;
calculating the speed of the tire to be measured according to the rotation period time, the diameter of the tire to be measured and the sampling frequency of the strain sensor;
constructing and obtaining a first dynamics model based on the ground contact patch length, the free rolling radius, the tire vertical force and the tire vertical rigidity;
and solving to obtain the tire vertical force of the tire to be measured according to the speed of the tire to be measured and the first dynamics model.
3. The method of claim 2, wherein the obtaining the ground contact time and the rotation cycle time of the tire to be measured from the strain waveform obtained by the strain sensing module comprises:
according to the strain waveform obtained by the strain sensing module, obtaining a plurality of data points of the strain sensor, and respectively carrying out first-order derivation, second-order derivation and third-order derivation on each data point;
when the multiplication of the second derivative of the (n+2) th data point and the second derivative of the previous point or the next point is smaller than or equal to 0 and the third derivative of the current data point is larger than 0, the current data point is put into a first-order guided wave valley candidate data point set, and n is the 1 st data point;
if the current data point is the last data point, clearing points with first order conduction less than a set threshold value in the first order guided wave valley candidate data point set;
starting from a first data point of remaining data points in the first-order guided wave valley candidate data point set, establishing a set width window, and extracting a data point with the minimum first order guide into the first-order guided wave valley data point set according to the set width window until no remaining data points exist in the first-order guided wave valley candidate data point set;
setting a set width window by taking each data point in the first-order guided wave valley data point set as a right edge, and extracting a data point value with the largest first-order guided wave peak data point value from the first-order guided wave valley data point set according to the set width window;
setting a current data point as a starting point and a next data point as b, if a is more than or equal to b, giving b as a next data point, if b is more than or equal to b, giving c as a last data point of a when b is more than a, if c=a, giving c as a last data point when c is more than a, taking a as a rear trough, traversing all data points in the first-order guided wave trough data point set, and obtaining all rear troughs in the first-order to trough data point set;
setting a current data point as a starting point and a previous data point as b, if a is more than or equal to b, giving b as a previous data point, if b is more than or equal to b, giving c as a next data point of a when b is more than a, if c=a, giving c as a next data point until c is more than a, traversing all data points in the first-order guided wave peak data point set by taking a as a money trough, and acquiring all previous data points in the first-order to peak data point set;
and determining the grounding time of the tire to be measured according to the front trough and the rear trough.
4. The method of measuring tire vertical force according to claim 2, wherein said calculating the ground contact angle of the tire to be measured from the ground contact time and the rotation cycle time comprises:
recording the ratio of the ground contact time to the rotation period time as the ground contact duty ratio of the tire;
multiplying the grounding duty ratio by the angle corresponding to the rotation period time to obtain the grounding angle of the tire to be measured, wherein the angle corresponding to the rotation period time is 360 degrees.
5. The method of claim 2, wherein calculating the footprint length of the tire to be measured based on the ground contact angle and the free rolling radius of the tire to be measured comprises:
the footprint length of the tire to be measured is calculated according to the following formula:
l＝R 0 *sinθ
C l ＝2l
wherein, the grounding trace is half-long and R 0 Is free rolling radius, theta is half of the grounding angle, C l Is the length of the ground trace.
6. The method of tire vertical force measurement according to claim 2, wherein calculating the speed of the tire to be measured based on the rotation cycle time, the diameter of the tire to be measured, and the sampling frequency of the strain sensor comprises:
the speed of the tire to be measured is calculated according to the following formula:
wherein v is the speed of the tire to be measured, D is the diameter of the tire to be measured, f is the sampling frequency of the strain sensor, and L is the rotation cycle time of the tire to be measured.
7. The method of tire vertical force measurement according to claim 2, wherein the first dynamics model is:
wherein C is l For ground trace length, R 0 Is of free radius F z For vertical force, C z For vertical stiffness, k 1 ，k 2 The number of times to be fitted.
8. The method for measuring the vertical force of the tire according to claim 7, wherein the solving the vertical force of the tire to be measured according to the speed of the tire to be measured and the first dynamics model comprises:
approximating the first kinetic model as a second kinetic model as follows:
wherein P is tire pressure;
and (3) substituting the speed of the tire into the second dynamic model for correction to obtain a third dynamic model as follows:
and solving the third dynamic model to obtain the tire vertical force of the tire to be measured.
9. A tire vertical force measurement apparatus, comprising:
the grounding angle calculation module is used for acquiring the grounding time and the rotation period time of the tire to be measured according to the strain waveform acquired by the strain sensing module and calculating the grounding angle of the tire to be measured according to the grounding time and the rotation period time;
the grounding mark length calculation module is used for calculating the grounding mark length of the tire to be measured according to the grounding angle and the free rolling radius of the tire to be measured;
the tire speed calculation module is used for calculating the speed of the tire to be measured according to the rotation period time, the diameter of the tire to be measured and the sampling frequency of the strain sensor;
the dynamics model construction module is used for constructing and obtaining a first dynamics model based on the length of the grounding trace, the free rolling radius, the vertical tire force and the vertical tire stiffness;
and the tire vertical force solving module is used for solving and obtaining the tire vertical force of the tire to be measured according to the speed of the tire to be measured and the first dynamics model.
10. A storage medium comprising a stored computer program, wherein the computer program, when run, controls a device in which the storage medium is located to perform a method of measuring tire vertical force as claimed in any one of claims 2 to 8.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410038879.2A CN117740226A (en) | 2024-01-10 | 2024-01-10 | Device and method for measuring vertical force of tire |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410038879.2A CN117740226A (en) | 2024-01-10 | 2024-01-10 | Device and method for measuring vertical force of tire |
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| Publication Number | Publication Date |
|---|---|
| CN117740226A true CN117740226A (en) | 2024-03-22 |
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|---|---|---|---|
| CN202410038879.2A Pending CN117740226A (en) | 2024-01-10 | 2024-01-10 | Device and method for measuring vertical force of tire |
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| CN (1) | CN117740226A (en) |
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2024
- 2024-01-10 CN CN202410038879.2A patent/CN117740226A/en active Pending
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