JP2017072396A - Acceleration correction device, acceleration correction program, and tire state detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To find a corrected acceleration detection value by removing a gravitational acceleration component from an acceleration detection value.SOLUTION: A transmitter comprises an acceleration sensor and a controller. A CPU of the controller obtains an acceleration detection value multiple times while a wheel makes one rotation. Then, the CPU sets the average value of acceleration detection values obtained multiple times as a corrected acceleration detection value.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an acceleration correction device, an acceleration correction program, and a tire condition detection device.

  When it is desired to detect the acceleration acting on the rotating body, an acceleration sensor is provided on the rotating body, and the rotating body and the acceleration sensor are rotated together. The acceleration sensor outputs an output signal corresponding to the acceleration acting on itself. An acceleration detection value acting on the rotating body can be obtained from this output signal. In Patent Document 1, an acceleration sensor is provided on a wheel serving as a rotating body, and acceleration acting on the wheel is detected.

  As described in Patent Document 1, in the tire condition monitoring device that monitors the condition of the tire, the tire condition detection device provided on the wheel detects the condition of the tire, and the detected information is provided on the vehicle body or the like. To the machine. The tire state detection device has an acceleration sensor that rotates integrally with a wheel, and the acceleration sensor detects acceleration and outputs an output signal (output voltage) corresponding to the acceleration. The tire condition detection device can obtain an acceleration detection value that is a detection value of acceleration from the output signal.

  Centrifugal acceleration and gravitational acceleration act on the acceleration sensor. Here, the acceleration sensor detects acceleration in a direction along the detection axis. When detecting the centrifugal force of the wheel as centrifugal acceleration, the acceleration sensor is attached so that the detection axis faces in the direction in which the centrifugal force acts. When the acceleration sensor is located at the lowest position (or highest position) of the wheel, if the detection axis is oriented in the vertical direction, the centrifugal acceleration acting on the wheel is detected regardless of the rotational position of the wheel. be able to. On the other hand, since the gravitational acceleration always acts in the vertical direction, when the wheel rotates and the direction of the detection axis changes, the gravitational acceleration that can be detected by the detection axis changes. It becomes impossible to detect all or part of the acceleration.

  Centrifugal acceleration detected by the acceleration sensor is output as a DC component of the output signal, and gravitational acceleration is output as an AC component of the output signal. For this reason, as shown in FIG. 9, the output signal of the acceleration sensor is a signal including a DC component and an AC component. As indicated by the straight line L1, when the speed of the vehicle increases, the rotational speed of the wheels increases, so that the centrifugal acceleration of the wheels increases and the output voltage increases. On the other hand, the gravitational acceleration detected by the acceleration sensor is a constant amount of change (± 1 G) during one rotation of the wheel regardless of the change in speed, and the alternating current included in the output voltage when the vehicle speed increases. The component is relatively smaller than the DC component.

JP 2013-159265 A

  By the way, since the output signal output from the acceleration sensor includes a centrifugal acceleration component and a gravitational acceleration component, the acceleration detection value obtained from the output signal adds a value corresponding to the gravitational acceleration component to the centrifugal acceleration value. Value. Here, when it is desired to obtain only the centrifugal acceleration value from the acceleration detection value, the gravitational acceleration component becomes an error component. For example, when it is desired to acquire the acceleration detection value every time the wheel rotates by a predetermined angle regardless of the speed of the vehicle, it is necessary to change the acquisition interval of the acceleration detection value according to the speed of the vehicle. Since the centrifugal acceleration acting on the wheel correlates with the speed of the vehicle, if the acquisition interval can be determined according to the centrifugal acceleration acting on the wheel, an acceleration detection value is obtained every time the wheel rotates by a predetermined angle. can do. However, since the acceleration detection value includes a gravitational acceleration component, it includes an error component of ± 1 G at the maximum. When the acquisition interval is determined from the acceleration detection value including an error component, an angle error occurs at a predetermined angle.

  Further, when determining whether or not the vehicle is traveling based on the acceleration detection value, a threshold for determining traveling is set, and it is determined that the vehicle is traveling when the acceleration detection value exceeds the threshold for traveling determination. . The running determination threshold is set to a value larger than the acceleration detection value when the vehicle is stopped, but the acceleration detection value includes a gravitational acceleration component for ± 1 G at the maximum regardless of the vehicle speed. It is. For this reason, it is necessary to set the threshold value for travel determination in consideration of the gravitational acceleration component. More specifically, when the centrifugal acceleration value when the vehicle is stopped is assumed to be 0G, a value greater than 0G may be set as the threshold for determination of traveling unless the gravitational acceleration component is considered. However, when the gravitational acceleration component is taken into account, even when the vehicle is stopped, an acceleration detection value of +1 G at the maximum is detected. For this reason, it is necessary to set a value larger than + 1G as the threshold value for travel determination, and the threshold value for travel determination becomes larger than when the threshold value for travel determination is set considering only the centrifugal acceleration. As a result, when the vehicle is traveling at a low speed, the traveling may not be detected from the acceleration detection value.

  An object of the present invention is to provide an acceleration correction device, an acceleration correction program, and a tire condition detection device that can obtain a corrected acceleration detection value obtained by removing a gravitational acceleration component from an acceleration detection value.

  In an acceleration correction apparatus that solves the above problem, an output signal of an acceleration sensor attached to the rotating body is input in such a manner that the direction in which the centrifugal force generated by the rotation of the rotating body acts and the direction in which the detection shaft extends are the same direction. An input unit, a derivation unit for deriving an acceleration detection value from the output signal corresponding to the acceleration acting on the detection axis, and the acceleration detection value from the derivation unit a plurality of times during one rotation of the rotating body. An acquisition unit for acquiring, and a removal unit for deriving a corrected acceleration detection value excluding the gravitational acceleration component based on the plurality of acceleration detection values acquired during one rotation of the rotating body.

  The acceleration detected by the acceleration sensor changes in a sine wave shape under the influence of gravitational acceleration. When it is desired to obtain only the centrifugal acceleration value from the acceleration detection value, the gravitational acceleration component (AC component) becomes an error component. If the acceleration detection value is acquired at the positive peak or negative peak of acceleration that changes sinusoidally when the acceleration detection value is acquired once while the rotating body makes one rotation, the centrifugal acceleration value is The difference is the largest. Here, when the rotation speed of the rotating body is constant and the acceleration detection value is acquired a plurality of times during one rotation of the rotating body, a plurality of acceleration detection values are obtained within a possible range of gravitational acceleration components with the centrifugal acceleration value as the center. Is acquired.

  The removal unit can derive a corrected acceleration detection value from which the gravitational acceleration component is removed from the acceleration detection value acquired a plurality of times. For example, the expected value when the acceleration detection value is acquired a plurality of times during one rotation of the rotating body and the average value of the acceleration detection values acquired a plurality of times is calculated is the centrifugal acceleration value. In addition, since the acceleration changes in a sine wave shape, the median value of the acceleration detection values acquired a plurality of times is closer to the centrifugal acceleration value than the acceleration detection value acquired at the positive peak or the negative peak. In any case, the difference between the corrected acceleration detection value and the centrifugal acceleration value is smaller than the acceleration detection value acquired at the positive peak or the negative peak. That is, it is possible to obtain a corrected acceleration detection value in which the gravitational acceleration component is reduced by removing at least a part of the gravitational acceleration component from the acceleration detection value.

About the said acceleration correction apparatus, the said removal part is good also considering the average value of the several acceleration detection value acquired while the said rotary body carried out 1 rotation as the said corrected acceleration detection value.
As described above, the acceleration detected by the acceleration sensor changes in a sine wave shape while the rotator rotates once. For this reason, when the rotation speed of the rotating body is constant and the average value of the acceleration detection values acquired a plurality of times is calculated, the expected value is the center of the sine wave, that is, the centrifugal acceleration. For this reason, the corrected acceleration detection value obtained by removing at least a part of the gravitational acceleration component from the acceleration detection value can be obtained by using the average value of the acceleration detection values as the correction acceleration detection value.

  About the said acceleration correction apparatus, the said acquisition part acquires the said acceleration detected value 4 times or more during one rotation of the said rotary body, and the said removal part is the some acquired while the said rotary body rotated 1 time. Of the acceleration detection values, an average value of the acceleration detection values excluding the maximum value and the minimum value may be used as the corrected acceleration detection value.

According to this, since the average value of the acceleration detection values excluding the acceleration detection value that is expected to have a large error component becomes the corrected acceleration detection value, the gravitational acceleration component is easily removed.
In the acceleration device, the acquisition unit acquires the acceleration detection value three times or more while the rotating body rotates once, and the removing unit acquires a plurality of accelerations acquired while the rotating body rotates once. The median value among the detected values may be used as the corrected acceleration.

  When the acceleration detection value is acquired three times or more, the median value is different from the acceleration detection value acquired at the positive peak or negative peak of the acceleration that changes in a sine wave shape. Therefore, by using the median value as the corrected acceleration detection value, an acceleration detection value from which at least a part of the gravitational acceleration component is removed is obtained as compared with the case where the acceleration detection value is acquired at the positive peak or the negative peak. be able to.

  In an acceleration correction program that solves the above problem, an output signal of an acceleration sensor attached to the rotating body is input in such a manner that the direction in which the centrifugal force generated by the rotation of the rotating body acts and the direction in which the detection shaft extends are the same direction. An input unit that derives an acceleration detection value that is a detection value of the acceleration from the output signal corresponding to the acceleration acting on the detection axis, and an acquisition unit that acquires the acceleration detection value from the derivation unit An acceleration correction program for deriving the corrected acceleration detection value by an acceleration correction apparatus comprising: a removal unit for deriving a corrected acceleration detection value excluding the gravitational acceleration component; The acceleration detection value is acquired a plurality of times during rotation, and the gravitational acceleration is performed based on the plurality of acceleration detection values acquired during one rotation of the rotating body in the removal unit. To derive the correction acceleration detected value excluding the component.

According to this, it is possible to cause the acceleration correction apparatus to derive a corrected acceleration detection value by causing the acceleration correction apparatus to execute the acceleration correction program.
A tire state detection device that solves the above problem is a tire state detection device that is provided on each wheel of a vehicle having a rotation position detection unit that detects the rotation position of each of a plurality of wheels, and detects the state of the tire. And a transmission signal including data indicating the state of the tire detected by the state detection unit, and obtaining a rotational position of the wheel detected by the rotational position detection unit triggered by reception of the transmission signal The transmitting unit for transmitting to the wheel position specifying device for specifying which wheel each tire condition detecting device is provided on, the direction of the centrifugal force generated by the rotation of the wheel as a rotating body, and the detection shaft An acceleration sensor that is attached to the wheel in a manner in which the extending direction is the same direction, and that outputs an output signal corresponding to the acceleration acting on the detection shaft, An acceleration detection value that is a detection value of the acceleration at an acquisition interval set based on the acceleration correction device according to claim 4 and the corrected acceleration detection value derived by the acceleration correction device. By acquiring the acceleration acquisition unit that acquires the acceleration detection value at a predetermined angle while the wheel rotates once, the wheel when the acceleration detection value is acquired by the acceleration acquisition unit Acceleration detection acquired at the previous acquisition angle with the acquisition angle as the acquisition angle, with the acquisition angle acquired as the acquisition angle greater than the acceleration detection value acquired at the previous acquisition angle as the acquisition angle. Assuming that the acquisition angle at which the acceleration detection value smaller than the value is acquired is the decrease acquisition angle, the transmission signal is transmitted from the transmission unit when the increase acquisition angle and the decrease acquisition angle are arranged in a specific pattern. And a control unit for, a.

  The acceleration acquisition unit acquires acceleration detection values at predetermined angles while the wheel rotates once. It is rare that the speed of the vehicle changes suddenly while the wheel makes one revolution, and the change in centrifugal acceleration is small while the wheel makes one revolution. On the other hand, while the wheel rotates once, the gravitational acceleration detected by the acceleration sensor changes between + 1G and -1G. From these, it can be considered that the difference between the respective acceleration detection values when the acceleration detection values are acquired a plurality of times during one rotation of the wheel is a difference caused by the gravitational acceleration. And the change of the acceleration detection value resulting from gravity acceleration appears in a sine wave shape.

  Assuming that the difference in acceleration detection value during one rotation of the wheel is due to only gravitational acceleration, and that the acceleration detection value is acquired at a predetermined angle during one rotation of the wheel, an increase acquisition angle and a decrease acquisition The corners are arranged in the same pattern every time the wheel rotates. If the transmission signal is transmitted when the increase acquisition angle and the decrease acquisition angle are arranged in a specific pattern, the transmission signal is transmitted at a fixed position of the rotational position (rotation angle) of the wheel. In the wheel position identification device, the tire state detection device is provided on which wheel from the synchronization of the rotation position (angle) of the wheel to which each tire state detection device transmits a transmission signal and the rotation position detected by the rotation position detection unit. Identify what is being done.

  In order to transmit the transmission signal at a fixed position, it is necessary to acquire acceleration detection values at predetermined angles while the wheel rotates once. The speed of the vehicle changes due to acceleration / deceleration, and the time (one cycle) required for the wheel to make one revolution also changes. In order to acquire the acceleration detection value at a predetermined angle even when the vehicle speed changes, it is necessary to change the acquisition interval according to the vehicle speed. When the vehicle speed changes, the centrifugal force acting on the wheels also changes, so the wheel's centrifugal force is detected as centrifugal acceleration, and the acceleration detection value is determined at predetermined angles by determining the acquisition interval according to the centrifugal acceleration. Can be obtained. When determining the acquisition interval, the acceleration can be acquired at predetermined angles by determining the acquisition interval from the corrected acceleration detection value obtained by removing at least a part of the gravitational acceleration component from the acceleration detection value. In particular, when the vehicle speed is low and the centrifugal acceleration is small, the gravitational acceleration is relatively large. Therefore, by removing the gravitational acceleration, the transmission signal can be transmitted at a fixed position even when the vehicle is traveling at a low speed. Can do.

  According to the present invention, it is possible to obtain a corrected acceleration detection value obtained by removing the gravitational acceleration component from the acceleration detection value.

(A) is a schematic block diagram of the vehicle by which the acceleration correction apparatus in embodiment is mounted, (b) is a figure which shows the relationship between the detection axis | shaft of an acceleration sensor, and a wheel. (A) is a schematic block diagram which shows the rotation sensor unit in embodiment, (b) is a figure for demonstrating the pulse which generate | occur | produces in the detector in embodiment, and the count mode of a pulse. The schematic block diagram of a transmitter. (A) is a figure which shows the change of the acceleration detected by an acceleration sensor, (b) is a figure which shows the change of the acceleration by a gravitational acceleration value. Schematic which shows the pulse count value of each rotation sensor unit at the time of receiving the transmission signal transmitted from the transmitter of ID “1”. The figure which shows the change of the acceleration detected by the acceleration sensor. The figure which shows the change of the acceleration detected by the acceleration sensor. The flowchart which shows the process which a controller performs. The figure which shows the relationship between the output signal of an acceleration sensor, and the speed of a vehicle.

Hereinafter, an embodiment of an acceleration correction device, an acceleration correction program, and a tire condition detection device will be described.
As shown in FIG. 1A, the vehicle 10 is equipped with an ABS (anti-lock / brake system) 20 and a tire condition monitoring device 30. The ABS 20 includes an ABS controller 25 and rotation sensor units 21 to 24 respectively corresponding to the four wheels 11 of the vehicle 10. The first rotation sensor unit 21 corresponds to the left front wheel FL provided on the front left side, and the second rotation sensor unit 22 corresponds to the right front wheel FR provided on the front right side. The third rotation sensor unit 23 corresponds to the left rear wheel RL provided on the rear left side, and the fourth rotation sensor unit 24 corresponds to the right rear wheel RR provided on the rear right side. Each wheel 11 includes a vehicle wheel 12 and a tire 13 attached to the vehicle wheel 12. The ABS controller 25 is composed of a microcomputer or the like, and obtains the rotation position (rotation angle) of each wheel 11 based on the pulse count values from the rotation sensor units 21 to 24.

  As shown in FIG. 2A, each rotation sensor unit 21 to 24 as a rotation position detector includes a gear 26 that rotates integrally with the wheel 11, and a detector that is disposed so as to face the outer peripheral surface of the gear 26. 27. On the outer peripheral surface of the gear 26, a plurality of (48 in this embodiment) teeth are provided at equal angular intervals. The detector 27 detects a pulse generated by the rotation of the gear 26. The ABS controller 25 is wired to each detector 27 and determines the rotational position of each wheel 11 based on the pulse count value of each detector 27 (hereinafter, pulse count value). Specifically, every time the gear 26 rotates, the detector 27 generates a number of pulses corresponding to the number of teeth. The ABS controller 25 counts pulses generated in the detector 27. By dividing 360 degrees by the number of pulses generated in the detector 27 while the wheel 11 makes one rotation (360 degrees), it is possible to know how many times the gear 26 has rotated per pulse count.

  As shown in FIG. 2B, in this embodiment, the ABS controller 25 counts from 0 to 95 by counting the rising and falling edges of the pulse. In the present embodiment, the pulse count value increases by 1 every time the wheel 11 rotates 3.75 degrees.

Next, the tire condition monitoring device 30 will be described.
As shown in FIG. 1A, the tire condition monitoring device 30 includes a transmitter 31 attached to each of the four wheels 11 and a receiver 50 installed on the vehicle body of the vehicle 10. Each transmitter 31 is attached to the vehicle wheel 12 to which the tire 13 is attached so as to be disposed in the internal space of the tire 13. Each transmitter 31 as a tire condition detection device detects the condition of the corresponding tire 13 and wirelessly transmits a signal including data indicating the detected tire condition.

  As shown in FIG. 3, each transmitter 31 includes a pressure sensor 32, a temperature sensor 33, an acceleration sensor 34, a controller 35, a transmission circuit 36, a transmission antenna 38, and a battery 37 serving as a power source for the transmitter 31. . The transmitter 31 is operated by the power supplied from the battery 37, and the controller 35 controls the operation of the transmitter 31 in an integrated manner. The pressure sensor 32 detects a corresponding pressure in the tire 13 (in-tire pressure), and outputs a signal corresponding to the pressure to the controller 35. The temperature sensor 33 detects the temperature in the corresponding tire 13 (in-tire temperature) and outputs a signal corresponding to the temperature to the controller 35. In the present embodiment, the pressure in the tire 13 and the temperature in the tire 13 are detected as the state of the tire 13 by using the pressure sensor 32 and the temperature sensor 33 as the state detection unit.

  As shown in FIG. 1B, the acceleration sensor 34 detects the acceleration acting on itself by rotating integrally with the wheel 11 as a rotating body. The acceleration sensor 34 of the present embodiment is provided so that the detection shaft 34a faces the vertical direction (downward) when the transmitter 31 is located at the lowest position of the wheel 11. The acceleration sensor 34 detects the acceleration in the direction along the detection axis 34a. The direction in which the detection shaft 34 a extends is the same as the direction in which the centrifugal force acts regardless of the rotational position of the wheel 11, and the acceleration sensor 34 detects the centrifugal acceleration regardless of the rotational position of the wheel 11. On the other hand, since the gravitational acceleration always acts in the vertical direction, the acceleration sensor 34 detects a component of gravitational acceleration (gravity acceleration component) when the detection axis 34a is not oriented in the vertical direction. The acceleration sensor 34 outputs an output signal (output voltage) corresponding to acceleration obtained by adding gravity acceleration to centrifugal acceleration.

  As shown in FIG. 4A, it is assumed that the vehicle 10 accelerates to time T1, travels at a constant speed from time T1 to time T2, and decelerates from time T2. The acceleration detected by the acceleration sensor 34 increases until time T <b> 1 due to an increase in centrifugal acceleration due to acceleration of the vehicle 10, and decreases from time T <b> 2 due to a decrease in centrifugal acceleration due to deceleration of the vehicle 10. Further, the acceleration is substantially constant between time T1 and time T2 when the vehicle 10 is traveling at a constant speed. Although the gravitational acceleration always works in the vertical direction, the detection shaft 34a changes its direction with the rotation of the wheel 11, so that the gravitational acceleration detected by the acceleration sensor 34 varies depending on the rotational position of the wheel 11. The acceleration changes in a sinusoidal shape due to gravitational acceleration.

  In FIG. 4B, the portion indicated by reference numeral A1 in FIG. The AC component included in the acceleration changes in a sine wave shape between ± 1 G (a voltage corresponding to) due to the rotation of the wheel 11. If the angle of the wheel 11 when the transmitter 31 is located at the foremost position of the wheel 11 is 0 degree, and the angle when the wheel 11 moves forward in the direction in which the vehicle 10 moves forward is positive, the angle of the wheel 11 is At 0 degree, the acceleration sensor 34 detects an acceleration obtained by adding 0 G as a gravitational acceleration to the centrifugal acceleration. When the angle of the wheel 11 is +90 degrees, the transmitter 31 (acceleration sensor 34) is positioned at the lowest position of the wheel 11, and the acceleration sensor 34 detects an acceleration obtained by adding + 1G as a gravitational acceleration to the centrifugal acceleration. When the angle of the wheel 11 is +180 degrees, the transmitter 31 is located at the last position of the wheel 11, and the acceleration sensor 34 detects an acceleration obtained by adding 0 G as a gravitational acceleration to the centrifugal acceleration. When the angle of the wheel 11 is +270 degrees, the transmitter 31 is positioned at the uppermost position, and the acceleration sensor 34 detects an acceleration obtained by adding −1 G as a gravitational acceleration to the centrifugal acceleration.

  As shown in FIG. 3, the controller 35 includes a CPU 35a, a microcomputer including a storage unit (RAM, ROM, etc.) 35b, and a timer 35c. The storage unit 35b has an ID that is identification information unique to each transmitter 31. Is registered. This ID is information used to identify each transmitter 31 in the receiver 50. In the present embodiment, the ID of the transmitter 31 provided on the left front wheel FL is “1”, the ID of the transmitter 31 provided on the right front wheel FR is “2”, and the transmitter 31 provided on the left rear wheel RL. The ID of the transmitter 31 provided on the right rear wheel RR is “4”. For convenience of explanation, the ID is expressed by “1” to “4”, but the ID is not limited to this.

  The controller 35 includes a pressure input unit I1 to which a signal from the pressure sensor 32 is input, a temperature input unit I2 to which a signal from the temperature sensor 33 is input, and an input unit I3 to which an output signal from the acceleration sensor 34 is input. And.

  The controller 35 acquires the in-tire pressure detected by the pressure sensor 32, the in-tire temperature detected by the temperature sensor 33, and the acceleration detection value detected by the acceleration sensor 34 at predetermined acquisition intervals. . Specifically, the controller 35 includes an AD converter 35d, and signals output from the sensors are converted into digital signals. The CPU 35a acquires the tire internal pressure, the tire internal temperature, and the acceleration detection value by acquiring a digital signal from the AD converter 35d at a predetermined acquisition interval. In the present embodiment, the AD converter 35d is a derivation unit, and the CPU 35a is an acquisition unit.

  As shown in FIG. 4B, the CPU 35a as the acceleration acquisition unit acquires acceleration detection values every time the wheel 11 is positioned at 10 acquisition angles P1 to P10 during one rotation (one cycle). Control as follows. Although the rotation speed of the wheel 11 changes due to acceleration / deceleration by the driver, the time required for the wheel 11 to make one rotation can be calculated based on the acceleration detection value of the acceleration sensor 34. As described above, since the acceleration detection value of the acceleration sensor 34 changes depending on the speed of the vehicle 10, the speed of the vehicle 10 and thus the time required for one rotation of the wheel 11 can be calculated based on the acceleration detection value. it can. The CPU 35a determines an acquisition interval obtained by dividing the time required for the wheel 11 to make one rotation into 10 equal parts, and acquires an acceleration detection value at the determined acquisition interval. As a result, the CPU 35a acquires the acceleration detection value at every 36 degrees that is an angle difference between the acquisition angles P1 to P10 while the wheel 11 makes one rotation.

  The CPU 35a serving as the control unit outputs tire pressure data, tire temperature data, and data including ID to the transmission circuit 36. The transmission circuit 36 as a transmission unit modulates data from the CPU 35 a to generate a transmission signal, and wirelessly transmits the transmission signal from the transmission antenna 38.

  As illustrated in FIG. 1A, the receiver 50 includes a reception controller 51, a reception circuit 52, and a reception antenna 54. A display 53 is connected to the reception controller 51 of the receiver 50. The reception controller 51 includes a reception side CPU 51a, a reception side storage unit (ROM, RAM, etc.) 51b, a microcomputer including a reception side timer 51c, etc., and the reception side storage unit 51b comprehensively controls the operation of the receiver 50. A program to be controlled is stored. The reception circuit 52 demodulates the transmission signal received from each transmitter 31 through the reception antenna 54 and sends it to the reception controller 51.

  The reception controller 51 grasps the state of the tire 13 (in-tire pressure and in-tire temperature) corresponding to the transmission source transmitter 31 based on the transmission signal from the reception circuit 52. The reception controller 51 causes the display 53 to display information related to the tire internal pressure.

  The reception controller 51 is connected to the ABS controller 25 and can acquire the pulse count values of the rotation sensor units 21 to 24 through the ABS controller 25.

Next, a wheel position specifying process for specifying which of the wheels 11 each transmitter 31 is provided on will be described. First, the transmitter 31 will be described in detail.
As shown in FIG. 4B, the controller 35 of the transmitter 31 acquires acceleration detection values at the respective acquisition angles P1 to P10. The controller 35 compares the acceleration detection value acquired at one acquisition angle with the acceleration detection value acquired at the acquisition angle one time before the acquisition angle, and detects the acceleration detection value acquired at each acquisition angle. Is increased or decreased from the acceleration detection value acquired at the previous acquisition angle. An acquisition angle obtained by acquiring an acceleration detection value greater than the acceleration detection value acquired at the previous acquisition angle is set as an increase acquisition angle, and an acceleration detection value smaller than the acceleration detection value acquired at the previous acquisition angle is obtained. The acquired acquisition angle is set as a reduced acquisition angle. Note that, in the present embodiment, an acquisition angle that has acquired the same acceleration detection value as the acceleration detection value acquired at the previous acquisition angle is an acquisition angle different from the previous acquisition angle. Specifically, if the previous acquisition angle is an increase acquisition angle, a decrease acquisition angle is used, and if the previous acquisition angle is a decrease acquisition angle, an increase acquisition angle is used.

  In FIG. 4B, “+” is added to the increase acquisition angle, and “−” is added to the decrease acquisition angle. In the following description, the increase acquisition angle is expressed as “+” and the decrease acquisition angle is expressed as “−” as appropriate. The acceleration detection value is a value obtained by adding a gravitational acceleration component to the centrifugal acceleration value. However, the time required for the wheel 11 to make one rotation is very short, and the speed of the vehicle 10 rarely changes abruptly during that time. is there. Therefore, the change in the acceleration detection value between the acquisition angles P1 to P10 can be regarded as a change caused by the gravitational acceleration component, ignoring the change in centrifugal acceleration.

  When the acceleration detection value is acquired for each predetermined angle while the wheel 11 rotates once, the increase acquisition angle and the decrease acquisition angle are arranged in the same pattern for each rotation of the wheel 11. Then, the CPU 35a causes the transmission circuit 36 to transmit a transmission signal when the increase acquisition angle and the decrease acquisition angle during one rotation of the wheel 11 are arranged in a specific pattern.

  In the present embodiment, a transmission signal is transmitted when the transmitter 31 straddles the lowest position of the wheel 11. When the transmitter 31 straddles the lowest position of the wheel 11, the acquisition angles are arranged in the order of “+” and “−” in the forward direction of the vehicle 10. When the acquisition angles are arranged in the order of “+” and “−”, it is possible to grasp that the transmitter 31 has straddled the lowest position of the wheel 11, and the transmitter is transmitted by transmitting a transmission signal at the timing of “−”. A transmission signal is transmitted at a timing at which 31 crosses the lowest position of the wheel 11.

  In the present embodiment, in order to prevent the transmission signal from being transmitted due to the reversal of the increase or decrease of the accidental acceleration detection value due to disturbance or the like, the acquisition angle is a specific pattern “+” “+” “−” “ When arranged in the order of “-”, it is considered that the transmitter 31 has straddled the lowest position of the wheel 11. Then, the controller 35 causes the transmission signal to be transmitted at the acquisition angle that is the second “−” of the specific pattern.

  The number of times that the CPU 35a acquires the acceleration detection value during one rotation of the wheel 11 is ten. It is assumed that 0 to 359 degrees are equally divided by 10 acquisition angles P1 to P10, and the acquisition angles are set every 36 degrees, with 0 degrees being P1. The second “−” of the specific pattern is 144 degrees. And a transmission signal is always transmitted when the wheel 11 is 144 degree | times by transmitting a transmission signal with the acquisition angle P5 used as the 2nd "-" of a specific pattern.

Next, the receiver 50 will be described.
The reception controller 51 of the receiver 50 as the wheel position specifying device acquires the pulse count values (rotation positions of the wheels 11) of the rotation sensor units 21 to 24 from the ABS controller 25 at the time when the transmission signal is received. It is specified to which wheel 11 each transmitter 31 is provided.

  Of the four wheels 11, for example, the description will be given focusing on the wheel 11 provided with the transmitter 31 having the ID “1”. When the reception controller 51 receives the transmission signal transmitted from the transmitter 31 with ID “1”, it receives the pulse count values (rotation positions of the wheels 11) of the rotation sensor units 21 to 24 at the time when the transmission signal is received. Obtained from the ABS controller 25. The rotational speed of each wheel 11 varies depending on the influence of the differential gear. For this reason, when the pulse count value of each rotation sensor unit 21 to 24 is acquired a plurality of times when the transmission signal transmitted from the transmitter 31 with ID “1” is received, the transmitter 31 with ID “1” is provided. Only the pulse count values of the rotation sensor units 21 to 24 corresponding to the wheels 11 are reduced. If the transmission signal is always transmitted at a fixed position (144 degrees), the pulse count value of one rotation sensor unit among the plurality of rotation sensor units 21 to 24 is always the same value. When the transmission signal is received a plurality of times and the pulse count value of each rotation sensor unit 21 to 24 is acquired every time the transmission signal is received, the difference between the pulse count values of each rotation sensor unit 21 to 24 is obtained, It can be specified that the transmitter 31 with ID “1” is provided on the wheel corresponding to the rotation sensor unit with small variation.

  As shown in FIG. 5, in this embodiment, the pulse count value of the rotation sensor unit 21 corresponding to the left front wheel FL shows a constant value. For this reason, it can be understood that the wheel 11 provided with the transmitter 31 with the ID “1” is provided on the left front wheel FL of the vehicle 10. The same processing is performed on the transmitters 31 with IDs “2”, “3”, and “4”, thereby identifying which wheel 11 the transmitter 31 with each ID is provided on.

  As described above, if the transmitter 31 always transmits a transmission signal at a certain position, it is possible to identify which transmitter 31 is provided on which wheel 11. However, in practice, due to the acquisition interval at which the acceleration detection value is acquired, the tolerance of the members constituting the transmitter 31, the measurement error of the acceleration detection value, etc. Varies. When the variation in the angle at which the transmitter 31 transmits a transmission signal becomes large, it is acquired by the rotation sensor unit corresponding to the wheel 11 provided with the transmitter 31 that transmits the transmission signal when the transmission signal is received. The variation in the pulse count value also increases. Then, the difference between the pulse count value acquired by the rotation sensor unit corresponding to the wheel 11 provided with the transmitter 31 that has transmitted the transmission signal and the pulse count value acquired by other rotation sensor units becomes large. It is difficult, and there is a possibility that the time required for specifying which wheel 11 the transmitter 31 is provided on may be long. In the present embodiment, for convenience of explanation, the rotational position of the wheel 11 to which the transmission signal is transmitted is caused only by the acquisition interval for acquiring the acceleration detection value, and the tolerance of the members constituting the transmitter 31 is increased. Explain without considering. Hereinafter, the shift of the rotational position of the wheel 11 to which the transmission signal is transmitted will be described in detail.

  As described above, the acquisition interval for acquiring the acceleration detection value is determined based on the acceleration detection value. The centrifugal acceleration value included in the acceleration detection value varies depending on the speed of the vehicle 10 (the rotational speed of the wheel 11), and the gravitational acceleration component varies only depending on the rotational position of the wheel 11.

  As shown in FIG. 6, the acceleration detected by the acceleration sensor 34 changes in a sine wave shape. Assuming that the rotation speed of the wheel 11 is constant, when an acceleration detection value can be acquired at the center (half cycle) P12 of the sine wave, the acceleration detection value does not include a gravitational acceleration component and becomes a centrifugal acceleration value. On the other hand, when the acceleration detection value is acquired at the positive peak P11 or negative peak P13 of the acceleration that changes in a sine wave shape, the gravitational acceleration component becomes an error component, and the acceleration detection value becomes a centrifugal acceleration value ± 1G. When the acquisition interval of the acceleration detection value is determined based on the acceleration detection value, the rotational position of the wheel 11 to which the transmission signal is transmitted varies.

  For example, it is assumed that when the centrifugal acceleration is 5G, an acceleration detection value is acquired at the negative peak P13, and the acquisition interval is determined based on the acceleration detection value. Based on the acceleration detection value, the CPU 35a determines the acquisition interval so as to acquire the acceleration detection value 10 times while the wheel 11 rotates once. At this time, the speed of the vehicle 10 (the rotational speed of the wheels 11) is a speed corresponding to 5G, but the CPU 35a determines that the vehicle 10 is traveling at a speed corresponding to 4G. The CPU 35a determines the acquisition interval so as to acquire the acceleration detection value 10 times while the wheel 11 rotating at a speed corresponding to 4G rotates once.

  Then, the determined acquisition interval becomes longer than in the case of 5G. As a result, the acceleration detection value needs to be acquired 10 times while the wheel 11 rotates once, but the acceleration detection value can be acquired only 8 times while the wheel 11 rotates once. In the above description, since the centrifugal acceleration is 5G and the acquired acceleration detection value is 4G, the error of the acceleration detection value is 20%. For this reason, an error of 20% also occurs in the acquisition interval, and as a result, the acceleration detection value can be acquired only eight times while the wheel 11 makes one rotation.

  If the number of times the acceleration detection value is acquired during one rotation of the wheel 11 is 8, a difference occurs in the angle difference between the acquisition points. As described above, when the acceleration detection value acquired during one rotation of the wheel 11 is 10, the angle difference between the acquired turning points P1 to P10 is 36 degrees. On the other hand, as shown in FIG. 7, when the acceleration detection value acquired during one rotation of the wheel 11 is 8, the angle difference between the acquisition points P21 to P28 is 45 degrees. As a result, when the acceleration detection value is acquired only eight times during one rotation of the wheel 11, if the transmission signal is transmitted in a specific pattern, the transmission signal is transmitted at 180 degrees. When the acceleration detection value is acquired 10 times while the wheel 11 rotates once, the transmission signal is transmitted at 144 degrees, whereas when it is 8 times, the transmission signal is 180 degrees. A difference of 36 degrees occurs in the rotational position of the wheel 11 to be transmitted.

  Further, when the acceleration detection value is acquired at a positive peak (6G) when the centrifugal acceleration is 5G, the angle difference between the acquisition points is 30 degrees, and when a transmission signal is transmitted in a specific pattern, 150 The transmission signal is transmitted at a time. In the receiver 50, due to the shift of the rotational position of the wheel 11 to which the transmission signal is transmitted, a shift occurs in the pulse count value acquired from each of the rotation sensor units 21 to 24 when the transmission signal is received.

  Although the centrifugal acceleration increases as the speed of the vehicle 10 increases, the gravitational acceleration is constant regardless of the speed of the vehicle 10. For this reason, as the speed of the vehicle 10 increases, the gravitational acceleration becomes relatively smaller than the centrifugal acceleration, and even if the acquisition interval is determined by the acceleration detection value including the gravitational acceleration component, the influence of the gravitational acceleration component is affected. There are few.

  On the other hand, if the speed of the vehicle 10 is low, the influence of the gravitational acceleration is large, and the shift of the rotational position where the transmission signal is transmitted becomes large. As a result, when the vehicle 10 is running at a low speed, which transmitter 31 is provided on which wheel 11 cannot be specified, or the time required for specifying it becomes longer. In this embodiment, the corrected acceleration detection value obtained by removing at least a part of the gravitational acceleration component from the acceleration detection value is derived, and the acquisition interval is determined based on the corrected acceleration detection value, thereby reducing the influence of the gravitational acceleration component. Yes.

  In the present embodiment, the CPU 35a executes the acceleration correction program stored in the storage unit 35b, so that the controller 35 functions as an acceleration correction device and derives a corrected acceleration detection value. Hereinafter, the process executed by the CPU 35a by the acceleration correction program will be described together with the operation.

  As shown in FIG. 8, the CPU 35a acquires the acceleration detection value once (step S11). In step S12, the CPU 35a determines a temporary acquisition interval from the acceleration detection value. The provisional acquisition interval is determined by the same method as the acquisition interval when acquiring the acceleration detection value.

  In step S13, the CPU 35a acquires the acceleration detection value at a temporary acquisition interval. As an example, a case where an acceleration detection value is acquired at the negative peak P13 shown in FIG. 6 will be described. As described above, in this case, the acceleration detection value is acquired eight times while the wheel 11 rotates once.

  In step S14, the CPU 35a calculates an average value of the acceleration detection values acquired eight times. Since the acceleration detection value changes in a sine wave shape, if the rotation speed of the wheel 11 is constant, the expected value of the average value of the acceleration detection values acquired during one rotation of the wheel 11 is the center of the sine wave, that is, It becomes a centrifugal acceleration value. As described above, it takes only a short time for the wheel 11 to make one revolution, and it is considered rare that the speed of the vehicle 10 rapidly changes while the wheel 11 makes one revolution. For this reason, the rotational speed of the wheel 11 is considered constant.

  CPU35a as a removal part complete | finishes a process by using the average value of an acceleration detected value as a correction acceleration detected value. The corrected acceleration detection value is compared with the case where the acceleration detection value is acquired with positive and negative peaks regardless of the number of times the acceleration detection value is acquired while the wheel 11 makes one rotation and the rotational position of the wheel 11 from which the acceleration detection value is acquired. Thus, the gravitational acceleration component becomes a small value.

  The CPU 35a determines the acquisition interval of the acceleration detection value from the corrected acceleration detection value. Since at least a part of the gravitational acceleration component is removed from the corrected acceleration detection value, if the acquisition interval is determined from the corrected acceleration detection value, the variation in the rotational position of the wheel 11 to which the transmission signal is transmitted becomes small. In particular, even when the vehicle is traveling at a low speed where the influence of the gravitational acceleration component is large, the variation in the rotational position at which the transmission signal is transmitted can be reduced. The acquisition interval described above is determined at predetermined intervals, and the acquisition interval corresponding to the speed of the vehicle 10 at that time is determined.

  Note that, as described above, the corrected acceleration detection value is a value in which the gravitational acceleration component is reduced as compared with the case where the acceleration detection value is acquired with positive and negative peaks of acceleration detected by the acceleration sensor 34. However, since all gravitational acceleration components may not be removed, even if the acquisition interval is determined using the corrected acceleration detection value, there is a deviation from the “predetermined angle” for acquiring the acceleration detection value. Can occur. And thereby, a shift | offset | difference may arise also in the rotation position of the wheel 11 to which a transmission signal is transmitted. However, the rotational width deviation (angle difference) of the wheel 11 to which the transmission signal is transmitted is smaller than when the acceleration detection value is acquired once and the acquisition interval is determined based on the acceleration detection value. It becomes easy to specify which wheel 11 the transmitter 31 is provided on. In other words, the “predetermined angle” for acquiring the acceleration detection value has an allowable range, and the fixed position where the transmission signal is transmitted also has the allowable range.

Therefore, according to the above embodiment, the following effects can be obtained.
(1) The transmitter 31 includes an acceleration sensor 34. The CPU 35a of the controller 35 acquires the acceleration detection value a plurality of times while the wheel 11 rotates once. Then, the CPU 35a derives a corrected acceleration detection value obtained by removing at least a part of the gravitational acceleration component from the acceleration detection value acquired a plurality of times. In the embodiment, an average value of acceleration detection values acquired a plurality of times is used as a corrected acceleration detection value. Since the acceleration detected by the acceleration sensor 34 changes in a sine wave shape, the expected value of the average value of the acceleration detection values acquired a plurality of times is the centrifugal acceleration value. Thereby, a corrected acceleration detection value excluding at least a part of the gravitational acceleration component can be obtained.

  (2) The CPU 35a determines the acquisition interval of the acceleration detection value based on the corrected acceleration detection value. By determining the acquisition interval based on the corrected acceleration detection value obtained by removing at least a part of the gravitational acceleration component from the acceleration detection value, when the transmission signal is transmitted in a specific pattern, the variation in the rotational position of the wheel 11 ( (Angle difference) becomes smaller. For this reason, it is easy to identify which transmitter 31 is provided on which wheel 11 in the receiver 50. In particular, when the vehicle 10 travels at a low speed, the influence of gravitational acceleration is large, and the variation in the rotational position of the wheel 11 to which the transmission signal is transmitted tends to increase. By removing at least a part of the gravitational acceleration component from the acceleration detection value, it is possible to reduce the variation in the rotational position of the wheel 11 to which the transmission signal is transmitted even when the vehicle 10 is traveling at a low speed. For this reason, even when the vehicle 10 is traveling at a low speed, the receiver 50 can specify which transmitter 31 is provided on which wheel 11.

In addition, you may change embodiment as follows.
The average value of the remaining acceleration detection values may be used as the corrected acceleration detection value by removing the maximum value and the minimum value from the plurality of acceleration detection values acquired during one rotation of the wheel 11. The maximum and minimum acceleration detection values are expected to have a large difference from the centrifugal acceleration value. Therefore, the average value of the acceleration detection values excluding the maximum and minimum values is used as the corrected acceleration detection value. A corrected acceleration detection value having a small difference from the acceleration value can be acquired. In this case, as the provisional acquisition interval, an interval at which the acceleration detection value can be acquired four times or more while the wheel 11 rotates once is set.

  The average value of the maximum value and the minimum value among a plurality of acceleration detection values acquired while the wheel 11 makes one rotation may be used as the corrected acceleration detection value. Even in this case, the gravitational acceleration component included in the corrected acceleration detection value can be reduced as compared with the case where the acceleration detection value is acquired at the positive and negative peaks of acceleration.

  A median value may be used as a corrected acceleration detection value among a plurality of acceleration detection values acquired during one rotation of the wheel 11. Even in this case, the gravitational acceleration component included in the corrected acceleration detection value can be reduced as compared with the case where the acceleration detection value is acquired at the positive and negative peaks of acceleration. In this case, as the provisional acquisition interval, an interval at which the acceleration detection value can be acquired three times or more while the wheel 11 rotates once is set. In addition, when the acceleration detection value acquired during one rotation of the wheel 11 is an even number, one of the two median values may be used as the corrected acceleration detection value, or the average value of the two median values is corrected. It may be an acceleration detection value.

  In the case where at least one acceleration detection value can be acquired every time the wheel 11 makes a half rotation, a value obtained by subtracting -1 from the maximum value among the plurality of acceleration detection values may be used as the corrected acceleration detection value. A value obtained by adding +1 to the minimum value among the plurality of acceleration detection values may be used as the corrected acceleration detection value.

  In the embodiment, the acceleration detection value is acquired once and the temporary acquisition interval is determined before acquiring the acceleration detection value. However, the temporary acquisition interval may be determined in advance. When the provisional acquisition interval is determined in advance, it is assumed that the position of the transmitter 31 is specified when the speed of the vehicle 10 is greater than or equal to km, and in the situation where the vehicle 10 is traveling at that speed, the wheel 11 is 1 A temporary acquisition interval is set so that the acceleration detection value can be acquired a plurality of times during rotation.

  As described in the embodiment, the influence of the gravitational acceleration decreases as the speed of the vehicle 10 increases, and even if the influence of the gravitational acceleration is ignored, the variation in the rotational position of the wheel 11 to which the transmission signal is transmitted becomes small. Therefore, the acquisition interval of the acceleration detection value is determined from the corrected acceleration detection value only when the speed of the vehicle 10 is slow, and when the speed of the vehicle 10 becomes a speed at which the influence of the gravitational acceleration can be ignored, the corrected acceleration The acquisition interval may be determined from the acceleration detection value without deriving the detection value. Whether or not the speed of the vehicle 10 has reached a speed at which the influence of the gravitational acceleration can be ignored may be determined by whether or not the acceleration detection value detected by the acceleration sensor 34 exceeds a threshold value. The determination as to whether or not the threshold value has been exceeded may be made based on the detected acceleration value, or may be made based on the corrected acceleration detection value.

  In the embodiment, the acceleration detection value acquisition interval is determined using the corrected acceleration detection value. However, the correction acceleration detection value may be used in addition to determining the acceleration detection value acquisition interval. For example, when the determination as to whether the vehicle 10 is traveling is performed based on the acceleration detected by the acceleration sensor 34, the determination is performed based on whether or not the acceleration detection value exceeds a threshold value for traveling determination. At this time, if the corrected acceleration detection value exceeds the travel determination threshold, it is determined that the vehicle 10 is traveling, and if the corrected acceleration detection value is equal to or less than the travel determination threshold, the vehicle 10 stops. It may be determined that That is, as long as the gravitational acceleration component of the acceleration detection value is an error component, the corrected acceleration detection value can be used for any application, and the acceleration correction device is used in addition to the tire condition detection device. May be.

  In the embodiment, the controller 35 is caused to function as an acceleration correction device by causing the controller 35 to execute the acceleration correction program. However, the present invention is not limited to this. An acceleration correction device may be provided between the acceleration sensor 34 and the controller 35 so that the corrected acceleration detection value is output to the controller 35 from the acceleration correction device.

  The number of acceleration detection values acquired during one rotation of the wheel 11 may be any number as long as it is two or more. As the number of times of acquiring the acceleration detection value is increased, the difference between the corrected acceleration detection value and the centrifugal acceleration value is reduced, but the power consumption of the battery 37 is increased. Therefore, the acceleration detection value is acquired from these balances. The number of times (temporary acquisition interval) may be determined.

  In the embodiment, “+”, “+”, “−”, and “−” are specific patterns, but the present invention is not limited to this. For example, “+” and “−” may be a specific pattern, and “−”, “−”, “+”, and “+” may be a specific pattern. Further, “−”, “+”, “+”, “+”, “−”, “−”, and the like may be used, and any specific pattern can be set from patterns generated while the wheel 11 makes one rotation. Furthermore, it is good also as a specific pattern by combining these patterns.

  The detection shaft 34a may be oriented in the vertical direction when the acceleration sensor 34 is located at the uppermost position of the wheel 11. In this case, the sign of the gravitational acceleration (± 1 G) detected by the acceleration sensor 34 during one rotation of the wheel 11 is reversed from that of the embodiment.

  -By changing the number of teeth of the gear 26, the number of pulses generated in the detector 27 each time the wheel 11 rotates may be changed as appropriate. Moreover, you may change the pulse count number during one rotation of the wheel 11 by counting either rising or falling.

  An acceleration correction device may be provided on a rotating body other than the wheel 11. As the rotating body, an acceleration sensor 34 (acceleration sensor 34 attached with the detection shaft 34a tilted with respect to the horizontal direction) that detects acceleration including a gravitational acceleration component in addition to a centrifugal acceleration component is provided. Any rotating body may be adopted as long as the rotating body is provided.

  DESCRIPTION OF SYMBOLS 10 ... Vehicle, 11 ... Wheel, 31 ... Transmitter, 32 ... Pressure sensor, 33 ... Temperature sensor, 34 ... Acceleration sensor, 34a ... Detection axis, 35 ... Controller, 35a ... CPU, 35d ... AD converter, 36 ... Transmission circuit 50. Receiver.

Claims (6)

An input unit to which an output signal of an acceleration sensor attached to the rotating body is input in such a manner that the direction in which the centrifugal force generated by the rotation of the rotating body acts and the direction in which the detection shaft extends are the same direction;
A derivation unit for deriving an acceleration detection value from the output signal corresponding to the acceleration acting on the detection axis;
An acquisition unit that acquires the acceleration detection value a plurality of times while the rotating body makes one rotation from the deriving unit;
An acceleration correction apparatus comprising: a removal unit that derives a corrected acceleration detection value excluding a gravitational acceleration component based on the plurality of acceleration detection values acquired during one rotation of the rotating body.   2. The acceleration correction apparatus according to claim 1, wherein the removing unit uses an average value of a plurality of acceleration detection values acquired during one rotation of the rotating body as the corrected acceleration detection value. The acquisition unit acquires the acceleration detection value four times or more while the rotating body makes one rotation,
The said removal part makes the corrected acceleration detection value the average value of the acceleration detection value except the maximum value and the minimum value among the several acceleration detection values acquired while the said rotary body carries out 1 rotation. The acceleration correction apparatus according to 1. The acquisition unit acquires the acceleration detection value three times or more while the rotating body makes one rotation,
The acceleration correction apparatus according to claim 1, wherein the removing unit sets a median value among the plurality of acceleration detection values acquired while the rotating body makes one rotation as the corrected acceleration detection value. An input unit to which an output signal of an acceleration sensor attached to the rotating body is input in such a manner that the direction in which the centrifugal force generated by the rotation of the rotating body acts and the direction in which the detection shaft extends are the same direction;
A derivation unit for deriving an acceleration detection value that is a detection value of the acceleration from the output signal corresponding to the acceleration acting on the detection axis;
An acquisition unit for acquiring the acceleration detection value from the deriving unit;
An acceleration correction program for causing an acceleration correction device to derive a corrected acceleration detection value, comprising: a removal unit that derives a corrected acceleration detection value excluding a gravitational acceleration component;
The acquisition unit causes the acceleration detection value to be acquired a plurality of times during one rotation of the rotating body,
The acceleration correction program which makes the said removal part derive | lead-out the said corrected acceleration detection value except the said gravitational acceleration component based on the said several acceleration detection value acquired while the said rotary body makes 1 rotation. A tire state detection device provided on each wheel of a vehicle having a rotation position detection unit that detects a rotation position of each of a plurality of wheels,
A state detector for detecting the state of the tire;
Each tire is obtained by acquiring a rotation signal of the wheel detected by the rotation position detection unit triggered by reception of the transmission signal, with a transmission signal including data indicating the state of the tire detected by the state detection unit. A transmission unit for transmitting to a wheel position specifying device for specifying which wheel the state detection device is provided on, and
It is attached to the wheel in such a manner that the direction in which the centrifugal force generated by the rotation of the wheel as a rotating body acts and the direction in which the detection shaft extends are the same, and outputs an output signal corresponding to the acceleration acting on the detection shaft An acceleration sensor;
The acceleration correction device according to any one of claims 1 to 4,
By obtaining an acceleration detection value that is a detection value of the acceleration at an acquisition interval that is set based on the corrected acceleration detection value derived by the acceleration correction device, a predetermined angle during one rotation of the wheel An acceleration acquisition unit for acquiring the acceleration detection value;
The acquisition angle at which the wheel angle at which the acceleration detection value is acquired by the acceleration acquisition unit is used as the acquisition angle and an acceleration detection value that is greater than the acceleration detection value acquired at the previous acquisition angle is acquired. Is an increase acquisition angle, and an acquisition angle acquired an acceleration detection value smaller than the acceleration detection value acquired at the previous acquisition angle is a decrease acquisition angle, the increase acquisition angle and the decrease acquisition angle are specific patterns. And a control unit that causes the transmission signal to be transmitted from the transmission unit when lined up with each other.

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