JP2015137077A - Tire position registration system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire position registration system which can correctly judge a tire position.SOLUTION: A tire valve 4 includes a filter part 12 for eliminating other components than gravity in a gravity detection signal Sgr of a gravity detection part 9 and detects a specified position in a tire rotation direction based on the gravity detection signal Sgr obtained through the filter part 12. The filter part 12 is for example, an FIR filter having an imaginary component. A specified position correction part 34 corrects delay time of a filter output generated in a value depending on a frequency of filter input, and corrects the specified position detected in the tire valve 4.

Description

  The present invention relates to a tire position registration system for registering a tire valve ID in a receiver in association with a tire mounting position.

  2. Description of the Related Art Conventionally, as one function of a tire pressure monitoring system, a tire position registration system that automatically registers a tire valve ID (valve ID) in a receiver without using a trigger device such as an initiator is well known (Patent Document 1). Etc.) If the initiator is not required for registering the valve ID in the receiver, the number of components mounted on the vehicle can be reduced.

  The system of Patent Document 1 includes a first sensor (4a to 4d) provided on a wheel (2a to 2d) and four second sensors (5a to 5d) associated with specific positions in the vehicle. And a measurement system (3) for locating the wheel. The first sensor transmits signals (S4a to S4d) indicating the wheel position to the measurement system. The second sensor measures the angular position of the wheel and outputs the measured values (S5a to S5d). The measurement system determines the phase position (W1a to W3a, W1b to W3b) of the signal of the first sensor related to the measurement value, and the phase position stays within the predetermined allowable range (WTa, WTb) in the predetermined monitoring period. The wheel position is determined by checking whether or not.

Special table 2011-527971 gazette

  By the way, when the vehicle accelerates or decelerates or travels on a rough road, the wheel (tire) generates a centrifugal force corresponding to the situation, so the first sensor (tire valve) is not the gravity generated in the wheel. The component is detected, which is disadvantageous for correctly detecting the wheel position. Therefore, it is assumed that components other than gravity are removed by a filter unit (an example is an FIR filter) to more accurately detect the rotational position of the wheel. However, depending on the type of filter, there is a concern that a delay time occurs in the filter output, which hinders correct determination of the wheel position.

  The objective of this invention is providing the tire position registration system which can determine a tire position more correctly.

  A tire position registration system that solves the above problems is necessary for transmitting a radio wave including tire pressure data from a tire valve of each tire, and monitoring the pressure of each tire by receiving the radio wave by a receiver of a vehicle body. Yes, in the configuration in which the ID of the tire valve is registered in the receiver in association with the tire position, a filter unit through which a gravity detection signal of a gravity detection unit provided in the tire valve passes, and the filter unit A first processing unit capable of detecting that the tire valve is positioned at a specific position in a tire rotation direction based on the gravity detection signal, and notifying the receiver of the specific position wirelessly; and the gravity detection Based on the fact that when the signal is passed through the filter unit, a delay time corresponding to the frequency occurs in the gravity detection signal, a specific position correction unit that corrects the specific position, and A plurality of axle rotation information of each axle when the ear valve takes the specific position is acquired for each specific position, and by checking which axle rotation information the valve ID is synchronized with, the valve ID and the axle And a second processing unit that determines the tire position.

  According to this configuration, when detecting the specific position of the tire valve based on the gravity detection signal of the gravity detection unit, components other than the gravity of the gravity detection signal are removed by the filter unit, so when the tire valve is positioned at the specific position. This is advantageous in determining whether or not it has been done correctly. By the way, when the gravity detection signal is passed through the filter unit, a delay time corresponding to the frequency of the filter input may occur in the filter output depending on the type of the filter unit. That is, there is a concern that the delay time of the filter output changes depending on the gravity generated in the tire. This leads to a concern that an error (displacement) may occur with respect to the actual specific position when detecting the specific position. Therefore, a specific position correction unit is provided in the tire position registration system, and the delay time generated with a value corresponding to the frequency of the filter input is corrected, so that an appropriate specific position can be determined. Therefore, it is possible to determine the tire position more correctly.

  In the tire position registration system, it is preferable that the filter unit is an FIR filter having an imaginary component. According to this configuration, since the FIR filter in which the filter coefficient is set with the imaginary number component is used, the phase delay of the filter output can be reduced as compared with the filter unit in which the filter coefficient is set with the real number component. Therefore, it is possible to suppress the time delay of the gravity detection signal output from the filter unit. By the way, when an FIR filter having an imaginary component is used, the output wave with respect to the input wave depends on the frequency, so that the delay time of the filter output changes according to the frequency. Therefore, in this configuration, the delay time that changes in accordance with the frequency of the input wave is corrected by the specific position correction unit. Therefore, even if an FIR filter having an imaginary component is used, it is advantageous for determining the tire position more correctly. It becomes.

  In the tire position registration system, the specific position correction unit calculates the number of gravity sampling per rotation of the tire, calculates the delay time of the current filter output from the gravity sampling number, and based on the delay time, It is preferable to correct the specific position. According to this configuration, since the delay time is calculated by obtaining the number of gravity samplings per tire rotation, it is advantageous to correctly calculate the delay time generated at a value corresponding to the frequency of the filter input by a simple calculation. .

  In the tire position registration system, it is preferable that the correction of the specific position is performed on the tire valve side by providing the specific position correction unit at least on the tire valve. According to this configuration, it is possible to cope by providing a function of correcting the specific position mainly on the tire valve side.

  In the tire position registration system, the correction of the specific position is preferably performed on the receiver side by providing the specific position correction unit in the receiver. According to this configuration, it is possible to cope by providing a function for correcting the specific position mainly on the receiver side.

  According to the present invention, the tire position can be determined more correctly.

The lineblock diagram of the tire position registration system of one embodiment. Explanatory drawing which shows the component of the gravity component force detected with a tire valve. (A), (b) is a communication sequence diagram of a tire valve. Explanatory drawing of sampling logic of gravity force. The distribution map of axle rotation information (pulse count value) of each wheel in a certain ID. A distribution table of axle rotation information (pulse count value) created for each ID. Deviation mean and standard deviation formulas. The block diagram of a digital filter. The complex conversion figure of a gravity detection signal. (A) is the frequency characteristic figure of the real part of a gravity detection signal, (b) is the frequency characteristic figure of the imaginary part of a gravity detection signal. Input column diagram of filter coefficient calculation software. (A)-(c) is a wave form diagram of the fundamental wave of a gravity detection signal at the time of each gravity sampling number, and a FIR filter signal. Explanatory drawing when correcting the delay time of a filter part by the tire valve side. Explanatory drawing when correcting the delay time of a filter part by the tire valve side. Explanatory drawing when correcting the delay time of a filter part by the TPMS receiver side.

Hereinafter, an embodiment of a tire position registration system will be described with reference to FIGS.
[Description of tire pressure monitoring system]
As shown in FIG. 1, the vehicle 1 includes a tire pressure monitoring system (TPMS) 3 that monitors the air pressure and the like of each tire 2 (2 a to 2 d). The tire pressure monitoring system 3 includes tire valves 4 (4a to 4d) attached to the tires 2a to 2d. The tire valve 4 is a tire valve sensor in which a tire plug is provided with a sensor and a communication function. The tire pressure monitoring system 3 transmits a radio wave (valve radio wave) Sva associated with at least the pressure data and ID of the tire 2 from the tire valves 4 a to 4 d to the vehicle body 5. Monitor air pressure.

  The tire valve 4 detects a controller 6 that controls the operation of the tire valve 4, a pressure detection unit 7 that detects tire air pressure, a temperature detection unit 8 that detects the temperature of the tire 2, and gravity that occurs in the tire valve 4. And a transmission antenna 10 that enables radio wave transmission from the tire valve 4. A valve ID is written and stored in the memory 11 of the controller 6 as a unique ID of each tire valve 4. The pressure detector 7 is preferably a pressure sensor, for example. The temperature detector 8 is preferably a temperature sensor, for example. The gravity detector 9 is preferably an acceleration sensor (G sensor), for example. The transmission antenna 10 is preferably capable of transmitting a radio wave of, for example, a UHF (Ultra High Frequency) band.

  The tire valve 4 includes a filter unit 12 through which a gravity detection signal Sgr of the gravity detection unit 9 provided in the tire valve 4 is passed. The filter unit 12 is preferably a digital filter that serves to remove from the gravity detection signal Sgr, for example, a sudden gravity component caused by running on a rough road or a gravity component caused by centrifugal force generated during tire rotation. . The filter unit 12 is preferably a band-pass filter that passes only a predetermined frequency range in the gravity detection signal Sgr. The filter unit 12 is preferably a FIR (Finite Impulse Response) filter, for example.

  The vehicle body 5 includes a receiver (hereinafter referred to as a TPMS receiver 13) that monitors the air pressure of the tires 2a to 2d by receiving the radio waves Sva transmitted from the tire valves 4a to 4d. The TPMS receiver 13 includes a tire pressure monitoring ECU (Electronic Control Unit) 14 that controls the operation of the TPMS receiver 13 and a receiving antenna 15 that enables radio waves to be received by the TPMS receiver 13. In the memory 16 of the tire pressure monitoring ECU 14, the valve IDs acquired from the respective tire valves 4a to 4d are written and stored in association with the tire positions. The TPMS receiver 13 is connected to a display unit 17 that displays the monitoring result of the air pressure. It is preferable that the display part 17 is installed in the instrument panel in a vehicle, for example.

  When the reception antenna 15 receives the radio wave Sva transmitted from the tire valves 4a to 4d at a certain timing, the TPMS receiver 13 collates the valve ID in the radio wave Sva, and if the valve ID collation is established, Check the pressure data (air pressure data). If the air pressure is equal to or lower than the low pressure threshold, the TPMS receiver 13 displays on the display unit 17 that the tire air pressure is low. The TPMS receiver 13 performs the tire pressure determination for each received radio wave Sva, and monitors the tires 2a to 2d.

[Description of tire position registration system]
The tire pressure monitoring system 3 automatically associates the valve IDs of the tire valves 4a to 4d with the IDs of the tires 2a to 2d attached to the front, rear, left and right of the vehicle body 5 to the TPMS receiver 13 automatically. A tire position registration function to be registered, a so-called auto location function (tire position registration system 18) is provided. The tire position registration system 18 performs a plurality of operations to acquire the rotation position (rotation amount) of each axle 19 (19a to 19d) of the four wheels when the tire valves 4a to 4d take a specific position in the tire rotation direction. By ascertaining which valve ID is synchronized with which rotational position (rotation amount) of each axle 19a to 19d, the valve ID is associated with the axles 19a to 19d, and the tires 2a to 2d. The position of is determined.

  FIG. 2 illustrates a gravity component detected by the gravity detection unit 9. It is preferable that the gravity detection unit 9 detects the gravity component Gr in the axle direction (tire radial direction) with respect to the gravity G as the gravity applied to the tire valve 4. For example, if the centrifugal force is not taken into account, the gravitational component force Gr takes “−1G” or “+ 1G” when it is located at the peak (position “12 o'clock” or “6 o'clock”) in the tire rotation direction. . The detected gravity component Gr may be a tangential component force in the tire rotation direction.

  FIG. 3A illustrates a radio wave transmission sequence of the tire valve 4. It is preferable that the tire valve 4 alternately takes a first time zone T1 of a short time during which radio waves can be transmitted and a second time zone T2 of a long time during which radio waves are not transmitted. The first time period T1 is preferably “1 second”, for example. The second time period T2 is preferably “30 seconds”, for example. Thus, the tire valve 4 repeats the operation of transmitting radio waves during a limited time of 1 second with an interval of about 30 seconds.

  As shown in FIG. 1, the tire valve 4 can detect that the tire valve 4 is located at a specific position in the tire rotation direction based on the gravity detection signal Sgr that has passed through the filter unit 12. A first processing unit 20 for notifying the receiver 13 wirelessly is provided. The first processing unit 20 is preferably provided in the controller 6, for example.

  The first processing unit 20 includes a specific position detection unit 21 that can detect that the tire valve 4 is positioned at a specific position in the tire rotation direction, and a radio wave that indicates that the tire 2 is positioned at the specific position (for example, specific position information It is preferable to include a transmission processing unit 22 that transmits the radio wave Spi) from the tire valve 4 including at least the valve ID. The specific position detector 21 and the transmission processor 22 are preferably provided in the controller 6, for example. The specific position is preferably, for example, a peak position in the tire rotation direction (an example is a position of “12:00”). The detection of the peak position is preferably executed a plurality of times continuously before radio wave transmission. The transmission of the specific position information radio wave Spi may be executed a plurality of times, for example, according to the number of times the peak position is detected. The specific position information radio wave Spi is transmitted during a first time period T1 that the tire valve 4 periodically takes.

  The tire valve 4 preferably includes an information holding unit 23 that holds one or more specific position information Dgr indicating when the tire valve 4 took a specific position in the second time zone T2. This is because, for example, when the vehicle 1 travels at a low speed and the tire 2 rotates slowly, there may occur a situation in which the peak cannot be detected a predetermined number of times during the short first time period T1, so that the peak occurs in the second time period T2 where radio waves are not transmitted This is because the position is detected in advance. Also, for example, if the radio wave is transmitted only at a certain tire angle, when this point becomes null, it will continue to be affected by the null, but the transmission of this example In this case, since radio waves are transmitted at an arbitrary tire angle, there is no fixed influence of null. That is, there is also an advantage of preventing a risk that the reception rate of the TPMS receiver 13 is remarkably lowered in the determination of the tire position.

  The specific position information Dgr is preferably peak information that can determine when the tire valve 4 has taken a peak. The specific position information Dgr is constructed from the number of gravity sampling points Nx indicating how many times the measurement has been performed since the start of gravity sampling (actual gravity sampling), the gravity sampling interval time Tb that is the execution interval of gravity sampling, and the like. It is preferable.

  As shown in FIG. 3B, it is preferable that the information holding unit 23 detects a peak of a predetermined number of times (for example, 8 times) in a predetermined time zone that goes back from the start point T1a of the first time zone T1. . The transmission processing unit 22 sequentially transmits one or more specific position information Dgr held so far together with the valve ID in the number of the specific position information Dgr during the first time period T1 in which radio wave transmission is possible. Is preferred. That is, the transmission processing unit 22 causes the tire valve 4 to transmit the radio waves including the specific position information Dgr and the valve ID (for example, the specific position information radio wave Spi) in order from the tire valve 4 by the number of the specific position information Dgr held. The transmission processing unit 22 may transmit these specific position information radio waves Spi continuously so that the specific position information radio waves Spi for one packet are completely transmitted during the first time period T1. The specific position information radio wave Spi has a time length of about 10 ms, for example, and may be repeatedly transmitted at intervals of about 100 ms.

  As shown in FIG. 1, the tire position registration system 18 transmits a radio wave (an example is a specific position information radio wave Spi) that indicates that the tire valve 4 is located at a specific position (an example is a peak position) in the tire rotation direction. 4, the TPMS receiver 13 receives this radio wave, and each tire valve 4 a to 4 d has a specific position from the axle rotation detection unit 24 (23 a to 24 d) that can detect the rotation of each axle 19 a to 19 d. Axle rotation information (for example, a pulse count value) Dc is obtained for each specific position, and a check is made as to which axle rotation information Dc each valve ID is synchronized with. 19d is provided with a second processing unit 25 for determining the tire position. The second processing unit 25 is preferably provided in the tire pressure monitoring ECU 14, for example. The distribution is preferably, for example, “variation”, “average deviation”, “standard deviation”, or the like.

  The axle rotation detectors 24a to 24d are preferably ABS (Antilock Brake System) sensors provided on the axles 19a to 19d. In this case, the axle rotation information Dc is preferably the number of pulses detected by, for example, an ABS sensor, that is, a pulse count value. The axle rotation detection units 24a to 24d detect, for example, a plurality of (for example, 48) teeth provided on the axles 19a to 19d by the sensing unit on the vehicle body 5 side, thereby generating a rectangular wave-shaped pulse signal Spl as a TPMS. Output to the receiver 13. If the second processing unit 25 detects both the rising edge and the falling edge of the input pulse signal Spl, it detects 96 pulses (count value: 0 to 95) per tire rotation.

  The second processing unit 25 handles a plurality (eight in this example) of specific position information radio waves Spi transmitted as one packet, as individual data. Each time the second processing unit 25 receives the specific position information radio wave Spi, the axle rotation information Dc of each of the axle rotation detection units 24a to 24d is read, and the distribution is taken and the distribution is confirmed. The position of ˜2d is determined. Further, when the peak detection is executed in advance in the second time zone T2, the second processing unit 25 uses the axle rotation information Dc stored in the memory 11, and the axle for each specific position from the received specific position information Dgr. It is preferable to reversely calculate the rotation information Dc and determine the tire position from this reverse calculation value.

  As shown in FIG. 4, when the tire valve 4 is in the second time zone T2 in which radio waves are not transmitted, the gravitational component force Gr is read a predetermined time before the peak detection is started, and is read in order to confirm the gravity waveform. A gravity sampling interval time Ta having a longer time corresponding to the gravity component Gr is set. Then, the tire valve 4 starts pre-gravity sampling for detecting the gravitational force Gr at the gravity sampling interval time Ta.

  In the pre-gravity sampling, the tire valve 4 first monitors where the peak of the gravity component Gr is in the gravity sampling performed at the gravity sampling interval time Ta. For the peak, for example, it is preferable to determine the second “decrease” point when the gravity component Gr changes from decrease → decrease → increase → increase as the peak position. When the tire valve 4 detects the peak of the gravity component force Gr, the tire valve 4 again monitors the peak of the gravity component force Gr in order to measure one period of the pre-gravity sampling. When the tire valve 4 detects the peak of the gravity component Gr again, the tire valve 4 calculates the pre-gravity sampling period based on the time between the previous peak and the subsequent peak. Then, the tire valve 4 sets “Tb” corresponding to the period of the pre-gravity sampling as a gravity sampling interval time used in actual gravity sampling. That is, since the number of times of gravity sampling per rotation of the tire is determined by a specified value (for example, 12 times), the optimum gravity sampling interval time Tb is set so that the number of times of gravity sampling takes the specified value during actual gravity sampling. The

  The tire valve 4 executes actual gravity sampling at the gravity sampling interval time Tb. That is, the tire valve 4 repeatedly detects the gravitational force Gr at the gravity sampling interval time Tb, and detects a plurality of peak positions necessary for determining the tire position. In the case of this example, one period of actual gravity sampling is “Tr” having a time width including a specified number (for example, 12 times) of the gravity sampling interval time Tb.

  When the information holding unit 23 detects the peak position in the gravity sampling repeatedly executed at the gravity sampling interval time Tb, the information holding unit 23 stores the specific position information Dgr in the memory 11. Thereafter, the information holding unit 23 holds the specific position information Dgr in the memory 11 every time a peak is detected.

  As shown in FIG. 3, when the transmission processing unit 22 reaches the first time zone T1 in which radio wave transmission is possible, the specific position information Dgr held in the memory 11 is equal to the number of specific position information Dgr. The specific position information radio wave Spi is transmitted in order from the transmission antenna 10. The specific position information radio wave Spi is a signal including at least a valve ID and specific position information Dgr. Specifically, the specific position information radio wave Spi may be a signal including information such as a valve ID, the number of gravity sampling points Nx, a gravity sampling interval time Tb, and pressure data. The number of gravity sampling points Nx corresponds to the number (total number) of gravity samplings after the gravity sampling is started at the gravity sampling interval time Tb. The specific position information radio wave Spi may be continuously transmitted at a short interval of, for example, 100 ms so that it can be transmitted during the first time period T1.

  As shown in FIG. 5, the second processing unit 25 acquires the axle rotation information Dc of each axle rotation detection unit 24a to 24d every time the specific position information radio wave Spi is received. In the case of this example, the second processing unit 25 performs reverse calculation of the axle rotation information Dc stored in the memory 16 based on the received specific position information Dgr, and calculates a reverse calculation value for each specific position information Dgr. And the 2nd process part 25 takes the statistics of these back calculation values, and whenever it receives each specific position information electromagnetic wave Spi of a packet unit, it adds statistics and determines a tire position. That is, as shown in the figure, when the portion is calculated at the first packet and the tire position is not fixed at the first packet, the tire position is determined by adding the distribution of the second packet to the distribution of the first packet. The The same processing is repeated after the third packet, and the distribution is updated, and the tire position is determined from this distribution.

  As shown in FIG. 6, a specific example of tire position determination is illustrated. The second processing unit 25 creates a distribution table 26 as shown in FIG. The second processing unit 25 “absolute evaluation” for determining the correctness of the distribution alone in each axle rotation information Dc and “relative evaluation” for determining the correctness of the distribution between the other axle rotation information Dc. It is preferable to determine the tire position based on the results of these evaluations. Relative evaluation is an index for determining whether the own wheel is sufficiently synchronized with the other wheel by comparing the own wheel with the other wheel. In this example, “average of deviation” and “standard deviation” are given as examples of distribution. The average deviation and standard deviation are smaller as the determination result is better.

  As shown in FIG. 7, the average of the deviation is the same when the pulse count value is “x”, the total number of collected pulse count values is “n”, and the average of the collected pulse count values is “x ′”. It is calculated from the equation (α) in the figure. The standard deviation is calculated from the equation (β) in the figure. Hereinafter, “average deviation” and “standard deviation” are collectively referred to as “bias value”. The absolute evaluation is an evaluation for determining whether or not the bias value falls below a threshold value. Relative evaluation calculates the difference between the deviation value of the own wheel and the deviation value of the other wheel, and whether or not this difference is equal to or greater than the threshold, that is, the deviation value of the absolute evaluation of the own wheel is sufficiently larger than that of the other wheel It is evaluation which determines whether it is small. The second processing unit 25 determines that the axle 19 and the tire 2 are synchronized if the bias value is equal to or smaller than the threshold value in the absolute evaluation and the difference in the bias value is equal to or larger than the threshold value in the relative evaluation, and determines the combination. To do.

  In the case of the example in FIG. 6, the pulse count values of the left front axle 19b in ID1 are collected in the vicinity of “20”, so the deviation value of the left front axle 19b in ID1 is within the threshold value, and the left front axle 19b satisfies the absolute evaluation in ID1. To do. On the other hand, in ID1, each pulse count value of the right front axle 19a, the right rear axle 19c, and the left rear axle 19d takes a value that does not converge to one value, so these bias values take bad values. For this reason, since the difference between the deviation value of the left front axle 19b in ID1 and that of the other axle is equal to or greater than the threshold value, the relative evaluation is also satisfied. Therefore, since it can be confirmed that ID1 is synchronized with the left front axle 19b, these are linked and it is determined that ID1 is the left front tire 2b. Similarly, the tire positions are also determined in ID2 to ID4.

  If the position of all four wheels cannot be determined by one determination, the second processing unit 25 determines the positions of the remaining wheels by the same process. Then, the same processing is repeated until the positions are determined for all four wheels. When the second processing unit 25 completes the position determination for all four wheels, the determination result is written in the memory 16 and the tire position is updated. The tire position determination process may be executed each time the ignition switch of the vehicle 1 is turned on, for example.

[Digital filter settings]
As shown in FIG. 8, the filter unit 12 is generally constructed from a plurality of taps 27 connected in series. Each tap 27 is constructed from, for example, a delay block 28, a weight parameter 29, and an adder 30. The filter unit 12 switches the filter coefficient depending on how the weight parameter 29 is set. Further, when the number of taps 27 (the number of stages) is increased, steep filter characteristics can be obtained, and the filter characteristics are improved. The filter unit 12 needs to set a filter coefficient and the number of taps so that a gravity component caused by these factors can be extracted when the vehicle 1 travels on a rough road or when a large centrifugal force is applied to the gravity detection unit 9. .

  As shown in FIG. 9, the gravity detection signal Sgr of the gravity detection unit 9 takes an ideal sine wave (or cosine wave) unless an external force such as a centrifugal force is taken into consideration. For this reason, the ideal wave of the gravity detection signal Sgr can be expressed by a complex number, for example, according to Euler's theorem. That is, the gravity detection signal Sgr can be expressed as an aggregate of coordinates (cos θ, i · sin θ) in a complex plane with the horizontal axis as the real axis and the vertical axis as the imaginary axis (where “i” is an imaginary number). ).

  FIG. 10A illustrates the frequency characteristics of the filter unit 12. By the way, the cycle (frequency) of the gravity detection signal Sgr changes according to the rotational speed of the tire 2. Further, in order to accurately determine the position of the tire valve 4 in the tire rotation direction, it is necessary to determine the position based on, for example, a gravity detection signal Sgr from which signal components corresponding to traveling on a rough road or centrifugal force are removed. That is, the range of frequencies to be extracted as signal components used for determining the tire position in the gravity detection signal Sgr output from the gravity detection unit 9 is uniquely determined. This range of frequencies to be extracted becomes the pass band of the band pass filter.

  As shown in FIG. 10B, the frequency characteristic of the filter unit 12 is the frequency characteristic of the real part because the gravity detection signal Sgr can be expressed in terms of (cos θ, i · sin θ) on the complex plane. In addition to (illustrated in FIG. 10A), there is also an imaginary part frequency characteristic shown in FIG. 10B. That is, in reality, the frequency characteristics of the filter unit 12 include a frequency characteristic of the real part calculated from cos θ and a frequency characteristic of the imaginary part calculated from i · sin θ.

  FIG. 11 illustrates a specific setting example of the filter coefficient. The filter coefficient of the filter unit 12 is calculated by calculating an imaginary part obtained by expressing a signal component to be captured in the gravity detection signal Sgr as a complex number. For example, the filter coefficient of the filter unit 12 is preferably obtained by performing an inverse Fourier transform on the frequency characteristic (see FIG. 10B) of the imaginary part (in this example, “−i · sin θ”). As an example, in the inverse Fourier transform calculation, a calculation software input field 31 as shown in FIG. 11 is displayed on a computer screen or the like. The input column 31 is provided with a column 32 for setting the validity / invalidity of the real part and a column 33 for setting the validity / invalidity of the imaginary part for each frequency that can be detected by the gravity detection signal Sgr. Then, invalid “0” is input to the real part field 32 and valid “1” is input only to the frequency part desired to be extracted as the gravity detection part 9 in the imaginary part field 33. After the valid / invalid input, the inverse Fourier transform is started and a desired filter coefficient is calculated. The weight parameter 29 of the filter unit 12 is set so as to take the filter coefficient thus calculated.

[Correction function for specific position (peak position)]
As shown in FIGS. 12A to 12C, when an FIR filter (filter unit 12) having an imaginary number component is provided in the tire valve 4 and only a gravitational component based on tire rotation is extracted, the FIR filter can detect an input wave. The delay of the output wave varies depending on the frequency. In other words, the output wave must take the fundamental wave Sba, and the FIR filter signal Sfi is output with a delay time Tlag corresponding to the frequency. In the case of an FIR filter having a real number component, the delay is constant regardless of the frequency. In the case of an FIR filter having an imaginary number component as in this example, the output delay time Tlag changes according to the frequency. To do.

  Specifically, when the gravity sampling number Np per one rotation of the tire shown in FIG. 12A is “10 times”, the delayed sampling number Nlag is “3.5 times”, the delay time Tlag is “35 ms”, and the delay is The angle is “126 °”. When the gravity sampling number Np per one rotation of the tire shown in FIG. 12B is “12”, the delay sampling number Nlag is “3 times”, the delay time Tlag is “30 ms”, and the delay angle is “90 °”. Become. When the gravity sampling number Np per one rotation of the tire shown in FIG. 12C is “14 times”, the delay sampling number Nlag is “2.5 times”, the delay time Tlag is “25 ms”, and the delay angle is “64. 3 ° ".

  In the case of this example in which the tire position is determined by associating the specific position information Dgr of each valve ID with the axle rotation information Dc of each of the axles 19a to 19d, the specific position information Dgr is used to more correctly specify the tire position. And the axle rotation information Dc must be synchronized. That is, when an FIR filter having an imaginary component is used, a delay time Tlag corresponding to the frequency is generated in the filter output. If this is performed as it is, the specific position notified from the tire valve 4 is determined. The (peak position) and the axle rotation information Dc when the specific position (peak position) is actually taken do not match, which is disadvantageous for correctly determining the tire position. Therefore, in this example, in the FIR filter having an imaginary number component, the delay time Tlag is corrected according to the gravity sampling number Np. Incidentally, the correction of the delay time Tlag is synonymous with the correction of the delay angle in the tire rotation.

  As illustrated in FIG. 1, the tire position registration system 18 corrects a specific position based on the fact that a delay time Tlag occurs in the gravity detection signal Sgr when the gravity detection signal Sgr is passed through the filter unit 12. Is provided. For example, when the delay time Tlag is corrected by the tire valve 4, the specific position correction unit 34 is provided in the tire valve 4 (illustrated in FIG. 1). On the other hand, when the delay time is corrected by the TPMS receiver 13, the specific position correction unit 34 is provided in the TPMS receiver 13.

Next, operation | movement of the tire position registration system 18 is demonstrated using FIGS.
FIG. 13 shows an example in which “corrected specific position (peak position of tire rotation)” is transmitted from the tire valve 4 to the TPMS receiver 13 when the delay time Tlag is corrected on the tire valve 4 side. Here, for example, a specific example of correction of the delay time Tlag in 10 sampling / tire rotation will be described with reference to the delay time Tlag1 in 12 sampling / tire rotation.

  The delay time Tlag2 at the time of 10 samplings / one rotation of the tire is deviated from the reference delay time Tlag1 by a displacement amount U according to the gravity sampling number Np (10 times in the case of FIG. 13). That is, since the FIR filter signal Sfi is output later than usual, a point later than usual is calculated at the specific position. Therefore, if nothing is corrected at the specific position, the TPMS receiver 13 is notified of a point at a timing later than usual at the specific position.

  The specific position correction unit 34 calculates the gravity sampling number Np per one period of gravity sampling when transmitting the specific position information radio wave Spi to the TPMS receiver 13, and based on this gravity sampling number Np, the required displacement at this time Determine the quantity U. The specific position correction unit 34 derives the gravity sampling point number Nx based on the displacement amount U and notifies the TPMS receiver 13 of this. That is, the specific position correcting unit 34 goes back the actual peak detection point by the displacement amount U, specifies the gravity sampling point number “Nx−1” closest to the retroactive point as the corrected gravity sampling point number Nx, To the TPMS receiver 13. Incidentally, in the example in the figure, the sampling point two before the detection point of the actual peak position is specified as the corrected gravity sampling point number Nx.

  The specific position correction unit 34 calculates the displacement amount U of the delay time Tlag from the gravity sampling number Np and repeats the process of correcting the gravity sampling point Nx for each specific position information radio wave Spi to be transmitted, thereby correcting the corrected gravity sampling. The score Nx is transmitted to the TPMS receiver 13. That is, when the first specific position information radio wave Spi is transmitted, the gravity sampling point “Nx−1” is notified, and when the second specific position information radio wave Spi is transmitted, the gravity sampling point “Nx−” is transmitted. 2 ”is notified to the TPMS receiver 13 of the corrected gravity sampling points Nx unique to each peak.

  FIG. 14 shows an example in which “correction value Rk” is transmitted from the tire valve 4 when the delay time Tlag is corrected on the tire valve 4 side. In this case as well, a specific example of correction of the delay time Tlag in 10 sampling / tire rotation will be described with reference to the delay time Tlag1 in 12 sampling / tire rotation. When the specific position correction unit 34 of the tire valve 4 transmits the specific position information radio wave Spi to the TPMS receiver 13, the specific position correction unit 34 transmits a correction value Rk used for correcting the peak position. The correction value Rk is preferably information for notifying how many (how many) gravity sampling points Nx should be shifted in correcting a specific position, for example.

  When receiving the specific position information radio wave Spi, the second processing unit 25 corrects the gravity sampling point Nx in the same specific position information radio wave Spi based on the correction value Rk included in the specific position information radio wave Spi. That is, the second processing unit 25 does not use the gravitational sampling point number Nx in the specific position information radio wave Spi as it is, but uses a value (Nx-1, Nx-2, etc.) after correcting this with the correction value Rk. Used as the gravity sampling point Nx. In this way, the gravity sampling point number Nx notified from the tire valve 4 to the TPMS receiver 13 is corrected. The process of transmitting the correction value Rk from the tire valve 4 to the TPMS receiver 13 and correcting the delay time Tlag is repeatedly executed for each specific position information radio wave Spi.

  FIG. 15 shows an example in which the delay time Tlag is corrected on the TPMS receiver 13 side. In this case as well, a specific example of correction of the delay time Tlag in 10 sampling / tire rotation will be described with reference to the delay time Tlag1 in 12 sampling / tire rotation. The specific position correcting unit 34 calculates the gravity sampling number Np per tire rotation based on the specific position information radio wave Spi received from the tire valve 4, and corrects the delay time Tlag based on the gravity sampling number Np. The gravity sampling number Np is obtained, for example, by taking the difference between the gravity sampling point Nx in the specific position information radio wave Spi transmitted earlier in time series and the gravity sampling point Nx in the specific position information radio wave Spi transmitted later. Can be calculated.

  When reading the axle rotation information Dc corresponding to the received specific position, the second processing unit 25 acquires the axle rotation information Dc-1 at a timing corresponding to the gravity sampling number Np. That is, the specific position correction unit 34 does not read the axle rotation information Dc-0 corresponding to the gravity sampling point number Nx in the specific position information radio wave Spi as it is, but according to the gravity sampling number Np from the axle rotation information Dc-0. Axle rotation information Dc-1 of a point that is traced back by a predetermined time is read. Thus, when the axle rotation information Dc corresponding to the peak position is read, the axle rotation information Dc is corrected.

  The specific position correction unit 34 repeatedly performs the process of correcting the axle rotation information Dc based on the gravity sampling number Np every time it receives the specific position information radio wave Spi to be received. That is, when the first specific position information radio wave Spi is received, “Dc-1” is acquired as the axle rotation information Dc, and when the second specific position information radio wave Spi is received, the axle rotation information Dc is “ The axle rotation information Dc is separately determined in each specific position information radio wave Spi so as to obtain “Dc-2”.

  The correction of the delay time Tlag at the time of 14 sampling / tire rotation shown in FIG. 12C is basically the same as 10 sampling / tire rotation, and thus the description thereof is omitted. That is, since the FIR filter signal Sfi is output earlier than normal (12 samplings), the delay time Tlag is corrected to an appropriate value by delaying the delay time Tlag by the displacement amount U corresponding to the gravity sampling number Np. As described above, it is possible to correct each variation in the delay time Tlag that may occur when using the imaginary component FIR filter to a suitable value.

According to the configuration of the present embodiment, the following effects can be obtained.
(1) When the specific position (peak position) of the tire valve 4 is detected based on the gravity detection signal Sgr of the gravity detection unit 9, components other than the gravity of the gravity detection signal Sgr are removed by the filter unit 12. It is advantageous to more correctly determine when 4 is located at a specific position. By the way, when the gravity detection signal Sgr is passed through the filter unit 12, a delay time Tlag corresponding to the frequency of the filter input may be generated in the filter output depending on the type of the filter unit 12 (FIR filter having an imaginary component). . That is, there is a concern that the delay time Tlag of the filter output changes according to the gravity generated in the tire 2. This leads to a concern that an error (displacement) may occur with respect to the specific position actually taken when the specific position of the tire valve 4 is detected. Therefore, the specific position correction unit 34 is provided in the tire position registration system 18 to correct the delay time Tlag generated with a value corresponding to the frequency of the filter input, so that an appropriate specific position can be determined. Therefore, the tire position can be determined more correctly.

  (2) The filter unit 12 is an FIR filter in which a filter coefficient is set with an imaginary component. For this reason, the phase delay of the filter output can be reduced as compared with the filter in which the filter coefficient is set with the real number component. Therefore, the time delay of the gravity detection signal Sgr output from the filter unit 12 can be reduced. By the way, when an FIR filter having an imaginary component is used, the output wave with respect to the input wave depends on the frequency, so that the delay time Tlag of the filter output changes according to the frequency. Therefore, in this example, the delay time Tlag that changes in accordance with the frequency of the input wave is corrected by the specific position correction unit 34, so that the tire position can be more correctly determined even if an FIR filter having an imaginary component is used. Can do.

  (3) Since the delay time Tlag is calculated by obtaining the gravity sampling number Np per one rotation of the tire, it is advantageous for correctly calculating the delay time Tlag generated with a value corresponding to the frequency of the filter input by a simple calculation. .

  (4) The delay time Tlag can be corrected on the tire valve 4 side. In this case, the function of correcting the specific position can be dealt with by providing mainly the tire valve 4 side.

  (5) The delay time Tlag can be corrected on the TPMS receiver 13 side. In this case, the function of correcting the specific position can be dealt with by providing mainly the TPMS receiver 13 side.

  (6) The filter unit 12 is a bandpass filter that allows only a predetermined range of frequencies to pass. Therefore, since only the gravity detection signal Sgr when the tire 2 is rotating at a certain rotational speed (rotation cycle) passes through the filter unit 12, the gravity detection signal in the frequency range desired to be used for determining the specific position of the tire valve 4 Only Sgr can be acquired.

Note that the embodiment is not limited to the configuration described so far, and may be modified as follows.
The second processing unit 25 can also apply a weight to the radio wave (specific position information radio wave Spi) received from the tire valve 4 according to the running state at that time. For example, when the vehicle 1 is traveling at a low speed, the weight of the received radio wave is increased, and when the vehicle 1 is accelerating / decelerating, the weight of the received radio wave is decreased or the data itself is discarded. As a result, when the vehicle is in a driving state where it is assumed that accurate statistics can be obtained, a large weight is given to the received radio wave, so that the accuracy information can be added to the statistics of the axle rotation information Dc. That is, the distribution of the axle rotation information Dc of each axle 19a to 19d can be obtained with high accuracy in each valve ID. Therefore, it is advantageous to more correctly determine the tire position.

The weighting method can be changed to various modes.
The tire valve 4 may take a communication sequence of simply transmitting a radio wave including air pressure data without performing gravity monitoring after performing transmission of the specific position information radio wave Spi of one packet a predetermined number of times.

The specific position information Dgr collected during the second time zone T2 may be transmitted all at once when the first time zone T1 arrives when the first radio wave transmission is performed.
As the specific position information Dgr, for example, various information such as the time when the peak position is detected and the time traced back from the start point T1a of the first time zone T1 can be adopted.

The specific position is not limited to the peak position, and may be a specific position taken by the tire valve 4 in the tire rotation direction.
The axle rotation detection unit 24 may output a pulse count value detected during a certain time interval to the TPMS receiver 13 as count data.

The axle rotation detection unit 24 may transmit a detection signal to the TPMS receiver 13 wirelessly.
The axle rotation information Dc is not limited to the pulse count value, and can be changed to another parameter as long as it is similar to the rotation position of the axle 19.

  The tire valve 4 is not limited to pre-detecting the peak in the second time zone T2 in which the radio wave transmission is not performed, but the specific position information is detected at the peak detection timing in the first time zone T1 in which the radio wave transmission is possible. It may be one that transmits a radio wave Spi.

The tire valve 4 may periodically transmit the specific position information Dgr.
When the specific position information radio wave Spi is transmitted a plurality of times, the information of the gravity sampling interval time Tb may be transmitted only once.

  The tire position determination method is not limited to the method of determining the position by taking the distribution of the axle rotation information Dc of each axle 19a to 19d for each ID as described in the embodiment. For example, the tire position may be determined by averaging the axle rotation information Dc of each axle 19a to 19d for each valve ID and confirming which of the average values the ID is synchronized with. Thus, the tire position determination method can be appropriately changed to various modes.

The distribution is not limited to variation, average deviation, and standard deviation, and can be changed to other parameters as long as the synchronization between the valve ID and the axle 19 can be determined.
-The radio wave for auto location is not limited to being classified into Spi with respect to Sva. That is, the tire pressure notification radio wave Sva and the specific position information radio wave Spi can be handled as the same radio wave.

The filter unit 12 is not limited to the FIR filter, and can be changed to other types of filters.
The method for correcting the delay time Tlag by the specific position correcting unit 34 can be appropriately changed to various methods.

  The reference for correction is not limited to the amount of delay at 12 samplings / one rotation of the tire, but various values can be adopted.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2 (2a-2d) ... Tire, 4 (4a-4d) ... Tire valve, 5 ... Vehicle body, 9 ... Gravity detection part, 12 ... Filter part, 13 ... Receiver (TPMS receiver), 18 ... Tire position registration system, 19 (19a to 19d) ... axle, 20 ... first processing unit, 25 ... second processing unit, 34 ... specific position correction unit, Sva ... radio wave, Spi ... specific position information radio wave, Sgr ... gravity detection Signal, Dc: Axle rotation information, Np: Gravity sampling number, Tlag: Delay time.

Claims (5)

Necessary for transmitting a radio wave including tire pressure data from the tire valve of each tire and receiving the radio wave with a receiver of the vehicle body and monitoring the air pressure of each tire, and the tire valve ID corresponds to the tire position In addition, in the tire position registration system for registering in the receiver,
A filter unit through which a gravity detection signal of a gravity detection unit provided in the tire valve is passed;
Based on the gravity detection signal that has passed through the filter unit, it is possible to detect that the tire valve is located at a specific position in the tire rotation direction, and a first processing unit that wirelessly notifies the receiver of the specific position When,
When the gravity detection signal is passed through the filter unit, a specific position correction unit that corrects the specific position based on the fact that a delay time corresponding to the frequency occurs in the gravity detection signal;
A plurality of axle rotation information of each axle when each tire valve takes the specific position is acquired for each specific position, and by confirming which axle rotation information the valve ID is synchronized with, the valve ID And a second processing unit that determines the tire position by tying the vehicle and the axle. The tire position registration system according to claim 1, wherein the filter unit is an FIR filter having an imaginary number component. The specific position correction unit calculates the number of gravity sampling per rotation of the tire, calculates the delay time of the current filter output from the number of gravity sampling, and corrects the specific position based on the delay time. The tire position registration system according to claim 1 or 2, characterized by the above. The tire according to any one of claims 1 to 3, wherein the correction of the specific position is performed on the tire valve side by providing the specific position correction unit at least on the tire valve. Location registration system. The tire position according to any one of claims 1 to 3, wherein the correction of the specific position is performed on the receiver side by providing the specific position correction unit in the receiver. Registration system.