JP2004132871A - Sensor signal correction system, and load weight measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the precision of a signal output from a sensor. <P>SOLUTION: This sensor signal correction system is provided with a determination information storage means 34a for storing determination information for determining the presence of generation of a temperature difference between the sensor 21 and an attaching part for the sensor 21 in a vehicle, a start detecting means 31a for detecting start of a monitoring period for monitoring the generation of a predetermined temperature difference, and a reference value storage means 34b for storing as a reference value a value in response to the signal output from the sensor 21 corresponding to the start detected by the start detecting means 31a. The correction system is provided further with a temperature difference detecting means 31b for detecting the generation of the temperature difference, based on the signal output from the sensor 21 during the monitoring period and the judge-determination information stored in the determination information storage means 34a, and a correction means 31c for conducting correction to bring the signal corresponding to the detection into the reference value stored in the reference value storage means 34b, when the temperature difference detecting means 31b detects the generation of the temperature difference. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sensor signal correction device and a loaded weight measurement device, and more specifically, a sensor signal correction device that corrects a signal output from a sensor attached to a vehicle and that changes according to a load applied to the vehicle, and A load weight measurement, comprising: a sensor attached to a vehicle and generating a signal that changes in accordance with a load applied to the vehicle; and a load weight measurement unit configured to measure a load weight of the vehicle based on a signal generated by the sensor. It concerns the device.
[0002]
[Prior art]
The measurement of the loaded weight of a vehicle is mainly performed for a large vehicle such as a truck, and is performed for the purpose of preventing a traffic accident such as a rollover due to overloading and promotion of vehicle deterioration. The measurement of the weight of a conventional vehicle was carried out by placing the vehicle to be measured on a platform commonly called a kankan. However, because the facility is large and requires a large installation space, a platform The number is limited and many vehicles cannot be measured, and the installation cost increases.
[0003]
Therefore, in recent years, a self-weight meter that is mounted on a vehicle itself and measures a loaded weight has been provided. In a conventional weight meter mounted on a vehicle, for example, sensors for weight measurement, such as strain gauge sensors, are attached to both left and right ends of both front and rear axles (axles), and are applied to front, rear, left and right tires. The loaded weight is measured by the sum of the outputs of the sensors in proportion to the load.
[0004]
[Problems to be solved by the invention]
However, when the sensor is welded to the axle as described above, if there is no temperature difference between the sensor and the axle, the load signal output by the sensor is a signal corresponding to the load. If the temperature difference between the sensor and the axle changes suddenly due to a rise in the axle temperature immediately after the vehicle stops, etc., a difference occurs in the amount of expansion due to temperature, and this difference is detected by the sensor as distortion other than load. Then, since the sensor outputs a load signal including an error, there has been a problem that the measurement accuracy is reduced.
[0005]
Therefore, in order to eliminate the error due to the temperature difference between the sensor and the axle, it can be dealt with by detecting the temperature difference between the sensor and the axle and performing the temperature correction. Since it is necessary to use a sensor or the like, the above-described problem can be solved, but a new problem of an increase in the cost of the device arises.
[0006]
Therefore, in view of the above-described problems, the present invention provides a sensor signal correction device that can improve the accuracy of a signal output by a sensor and a loaded weight measurement device that can improve the accuracy of a loaded weight to be measured. The challenge is to do that.
[0007]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a sensor signal correction apparatus according to the present invention for solving the above-described problems, in accordance with a load applied to a vehicle output by a sensor attached to the vehicle, as shown in a basic configuration diagram of FIG. A sensor signal correction device that corrects a signal that changes according to whether the temperature difference has occurred between the sensor 21 and a mounting position of the sensor 21 in the vehicle based on a signal output by the sensor 21. Determination information storage means 34a for storing determination information for determination, start detection means 31a for detecting the start of a monitoring period for monitoring the occurrence of the predetermined temperature difference, and the start detection means 31a A reference value storage means 34b for storing, as a reference value, a value corresponding to the signal output from the sensor 21 in response to the start; A temperature difference detecting unit 31b that detects the occurrence of the temperature difference based on the input signal and the determination information stored in the determination information storage unit 34a, and when the temperature difference detecting unit 31b detects the occurrence of the temperature difference. And a correction unit 31c for correcting the signal corresponding to the detection to become the reference value stored in the reference value storage unit 34b.
[0008]
According to the sensor signal correction device of the present invention described in claim 1, when the start detection means 31a detects the start of the monitoring period, the value corresponding to the signal output by the sensor 21 in response to this detection is calculated. The reference value is stored in the reference value storage unit 34b. When a temperature difference occurs between the sensor 21 and the mounting position of the sensor 21 in the vehicle during the monitoring period, the temperature difference is determined based on the signal output from the sensor 21 and the determination information stored in the determination information storage unit 34a. Is detected by the temperature difference detecting means 31b. Then, the signal output from the sensor 21 corresponding to the detection of the occurrence of the temperature difference is corrected by the correction unit 31c so as to become the reference value stored in the reference value storage unit 34b.
[0009]
Therefore, determination information for determining whether or not there is a temperature difference between the sensor 21 and the mounting location of the sensor 21 in the vehicle based on a signal output from the sensor 21 is stored, and the temperature difference is determined during the monitoring period. Is detected, the signal output from the sensor 21 corresponds to the start of the monitoring period and is corrected so as to be the reference value before the temperature difference occurs. Therefore, the temperature difference between the sensor 21 and the mounting position of the vehicle is detected. Even if an error occurs in the output of the sensor 21 due to the difference in the expansion amount due to the temperature difference, the output can be corrected to an appropriate output. Therefore, the accuracy of the signal output from the sensor 21 can be improved without using a temperature sensor or the like.
[0010]
According to a second aspect of the present invention for solving the above-mentioned problem, as shown in the basic configuration diagram of FIG. 1, in the sensor signal correction apparatus according to the first aspect, the determination information storage means 34a stores The judging information has a configuration capable of discriminating a change due to the temperature difference and a change due to the load, and the temperature difference detecting unit 31b further includes a signal output by the sensor 21 during the monitoring period and the signal Based on the determination information stored in the determination information storage unit 34a, a change in the signal due to the load is detected, and the reference value storage unit 34b detects when the temperature difference detection unit 31b detects a change due to the load. A value corresponding to the signal corresponding to the detection is set as the reference value.
[0011]
According to the sensor signal correction device of the present invention described in claim 2, the signal of the signal is output based on the signal output by the sensor 21 during the monitoring period and the determination information stored in the determination information storage unit 34a. When the change due to the load is detected by the temperature difference detecting means 31b, a value corresponding to the signal output by the sensor 21 corresponding to this detection is stored in the reference value storing means 34b as a new reference value. Therefore, the change due to the temperature difference and the change due to the load can be determined based on the signal output from the sensor 21 and the determination information. Therefore, when the change in the load is detected during the monitoring period, the reference value of the reference value storage means is determined. By updating the value, even if the loading and unloading operations are performed during the monitoring period, it is possible to eliminate the error generated in the signal of the sensor 21 due to the temperature difference and correct the reference value to an accurate reference value. Therefore, even if unloading or loading occurs during the monitoring period, the correction is performed based on the accurate reference value, so that the accuracy of the signal output from the sensor 21 can be further improved.
[0012]
According to a third aspect of the present invention, there is provided a sensor signal correcting apparatus as set forth in the first or second aspect, wherein the sensor 21 is provided on an axle of the vehicle, as shown in a basic configuration diagram of FIG. And the start detecting means 31a starts the monitoring when detecting the stop of the vehicle based on a running state signal indicating a running state of the vehicle.
[0013]
According to the sensor signal correction device of the present invention described in claim 3, when the stop of the vehicle is detected by the start detecting means based on the traveling state signal, the signal output by the sensor 21 in response to the detection is obtained. The corresponding value is stored in the reference value storage means 34b as a reference value, and the monitoring period is started. Therefore, since the monitoring period is started in response to the stop of the vehicle, the vehicle stops after a long time running, and the temperature of the axle gradually increases, so that the sensor and the sensor on the vehicle side can be attached to the sensor. Even if an error occurs in the signal output from the sensor 21 due to the temperature difference, the error can be corrected. Therefore, if the ambient temperature changes, the axle and the sensor 21 change at almost the same temperature. However, since the axle of a vehicle that has traveled for a long time changes after stopping, a temperature difference between the axle and the sensor 21 tends to occur. Even if the sensor 21 is attached to the axle, the signal can be accurately corrected.
[0014]
According to a fourth aspect of the present invention, there is provided a weight measuring apparatus according to the present invention, which is mounted on a vehicle and outputs a signal that changes according to a load applied to the vehicle, as shown in a basic configuration diagram of FIG. In the loading weight measuring device including the generated sensor 21 and the loaded weight measuring means 31d for measuring the loaded weight of the vehicle based on the signal generated by the sensor 21, correction is made to the signal output by the sensor 21. The sensor signal correction device according to any one of claims 1 to 3, further comprising: when the correction unit 31c performs the correction, the loaded weight measurement unit 31d performs the correction based on the correction result corrected by the correction unit 31c. The measurement is performed.
[0015]
According to the load weight measuring device of the present invention described in claim 4, the load weight of the vehicle is measured by the load weight measuring means 31d based on the signal generated by the sensor 21. Then, when a temperature difference occurs between the sensor 21 and the mounting position of the sensor 21 in the vehicle and the signal output by the sensor 21 is corrected by the correction unit 31c of the sensor signal correction device, the load weight based on the correction result is loaded. It is measured by the weight measuring means 31d. Therefore, when the signal output from the sensor 21 is corrected, the load weight is measured based on the correction result. Therefore, even if a temperature difference occurs between the sensor 21 and the mounting location of the vehicle, Accurate loading weight can be measured. Therefore, since the influence of the temperature change of the sensor 21 is excluded and the measurement is performed based only on the change in the load, the accuracy of the loaded weight can be improved.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, one embodiment of a loaded weight measuring device to which a sensor signal correction device according to the present invention is applied will be described with reference to the drawings of FIGS.
[0017]
Here, FIG. 2 is a configuration diagram showing an example of a basic configuration of the loaded weight measuring device according to the present invention, FIG. 3 is a flowchart showing a part of a processing outline executed by the CPU of FIG. 2, and FIG. FIG. 5 is a flowchart showing another part of the outline of the processing executed by the CPU in FIG. 2, FIG. 5 is a flowchart showing an example of the loaded weight display processing in FIGS. 3 and 4, and FIG. It is a figure for explaining an example.
[0018]
In FIG. 2, reference numeral 30 denotes a loading weight measuring device, which generates a pulse signal (corresponding to a signal) that changes in accordance with the load applied to the bed of the vehicle and is provided on the front, rear, left and right axles and the like. The four sensing elements 21 serving as load measuring sensors, a traveling sensor 60 that outputs a traveling pulse having a cycle corresponding to the vehicle speed generated according to the traveling of the vehicle, and the like are connected, and power is supplied from the battery 2. I have.
[0019]
In the present embodiment, a strain type gage sensor or the like is used as the sensing element 21, and the load weight is measured by the sum of the outputs of the sensing elements 21 in proportion to the load applied to the front, rear, left, and right sensing elements 21. Therefore, the sensing element 21 functions as the sensor described in the claims.
[0020]
Reference numeral 31 denotes a central processing unit (CPU). The CPU 31 performs various processes and controls in accordance with a predetermined program. Reference numeral 32 denotes a read-only memory (ROM). The ROM 32 stores a program for the CPU 31 and the like. Reference numeral 33 denotes a readable / writable memory (RAM). The RAM 33 has a data area for storing various data generated in the process of the CPU 31, a work area used for the process, and the like.
[0021]
Reference numeral 34 denotes a non-volatile memory (NVM), and data stored in the NVM 34 is retained even when power supply is cut off. The NVM 34 includes tables such as offset adjustment and characteristic correction values for the output pulse signal of each sensing element 21, a weight conversion formula, an overload determination value of overload, and four bias load determination values of front, rear, left, and right. Stored in advance. Further, the NVM 34 stores a reference value corresponding to a frequency serving as a reference during a monitoring period for monitoring the occurrence of a temperature difference at the start of the monitoring period.
[0022]
In the present embodiment, the determination information is further stored in the NVM 34. For example, based on a signal output from the sensing element (sensor) 21, a temperature difference occurs between the sensing element 21 and the vehicle body such as an axle. For example, the determination information for determining whether or not the sensor element 21 is stored is stored in correspondence with the vehicle type, the type of the sensing element 21 to be corrected, the mounting position of the sensing element 21, and the like.
[0023]
As an example of the determination information, when the pulse signal from the sensing element 21 is measured every 0.5 seconds during the monitoring period, a configuration is provided having a determination threshold for determining a change due to a temperature difference and a change due to loading. Is done. In detail, in a configuration in which 100 Hz is converted as 1 ton, the determination threshold is ± 0.3 Hz, and if a change of less than ± 0.3 Hz is detected in 0.5 seconds, it is determined that the change is due to a temperature difference, and the change is determined in 0.5 seconds. If a change of ± 0.3 Hz or more is detected, it is determined that the change is due to loading. Note that the determination information is not limited to the above-described configuration, but may be variously different embodiments such as a configuration having a determination threshold according to the conveyed load.
[0024]
Therefore, in the present embodiment, since the determination information and the reference value are stored in the NVM 34, the NVM 34 functions as a determination information storage unit and a reference value storage unit described in the claims. It should be noted that the present invention can be implemented in various different embodiments, for example, the ROM 32 functions as the determination information storage unit and the RAM 33 functions as the reference value storage unit.
[0025]
Reference numeral 35 denotes an interface (I / F) unit. The interface unit 35 includes a sensing element I / F 35a, a display unit I / F 35b, an alarm unit I / F 35c, and a travel sensor I / F 35d. The sensing element I / F 35a supplies an exciting current to each of the sensing elements 21 to excite each of the sensing elements 21 and an AC voltage generated by exciting each of the sensing elements 21 and converts the AC voltage into a DC voltage. And a VF converter 35a3 that converts the converted DC voltage into a pulse signal having a frequency proportional to the voltage value and outputs the pulse signal to the CPU 31.
[0026]
Reference numeral 36 denotes a power supply unit, and the power supply unit 36 distributes and supplies power supplied from the battery 2 of the vehicle to a display unit 40, an alarm buzzer 47, an interface unit 35, and the like, which are configured by an LCD or the like. Reference numeral 37 denotes an RS-232C driver unit. By providing the RS-232C driver unit 37, connection with an external device such as a handy terminal is enabled.
[0027]
The above-described RAM 33 has a work area for storing various data such as a current frequency, a measurement frequency, a previous frequency, a weight corresponding to each sensing element 21, and a loaded weight, which will be described later.
[0028]
Next, an example of an outline of processing according to the present invention performed by the CPU 31 of the above-described vehicle load measuring device 30 will be described with reference to flowcharts shown in FIGS.
[0029]
When the process shown in FIG. 3 is started in response to the supply of electric power from the battery 2 of the vehicle, in step S1, a timeout is notified each time a predetermined measurement time (for example, 0.5 seconds) elapses. When a timeout is notified from the measurement timer in step S2, each frequency is measured based on a pulse signal input from each sensing element 21 via the sensing element I / F 35a. These are stored in the RAM 33 as the current frequency, and then the process proceeds to step S3.
[0030]
In step S3, it is determined whether or not the vehicle has stopped based on the traveling pulse input from the traveling sensor 60. In the present embodiment, the start of the monitoring period is defined as the start of energization of the sensing element 21 and the stop of the vehicle. Therefore, the determination process of step S3 corresponds to the start detection means described in the claims. I have.
[0031]
If it is determined in step S3 that the vehicle is not stopped (N in step S3), that is, it is determined that the vehicle is in a running state, and in step S4, the current frequency is set as the measurement frequency of the RAM 33 in step S4. Then, in step 5, the loaded weight display processing shown in FIG. 5 is called, and after returning from the loaded weight display processing, the flow proceeds to step S2.
[0032]
Here, the loading weight display processing shown in FIG. 5 will be described in detail.
In step T1, each weight is calculated in the RAM 33 from the measurement frequency corresponding to each sensing element 21 stored in the RAM 33 using the weight conversion formula of the NVM 34, and then, in step T2, the weight is calculated. The offset is adjusted by the offset adjustment value of the NVM 34, and then the process proceeds to step T3.
[0033]
In step T3, the weight based on the input signal from each sensing element 21 after the offset adjustment is characteristic-corrected by the characteristic correction value of the NVM 34. Then, in step T4, the loading is performed based on all the weights after the offset adjustment and the characteristic correction. The weight is calculated, and in step T5, the loaded weight information for displaying the calculated loaded weight on the display unit 40 is generated and output to the display unit I / F 35b, and thereafter, the process returns to the calling module. Then, the display unit I / F 35b causes the display unit 40 to display the input loaded weight information.
[0034]
Therefore, since the loading weight is measured based on the pulse signal output (generated) by the sensing element (sensor) 21 by the series of processing of steps T1 to T4, this series of processing is described in claims. Corresponds to the loaded weight measuring means.
[0035]
When returning from the loaded weight display processing, in step S6 shown in FIG. 3, the measurement frequency is set as the previous frequency of the RAM 33, and thereafter, the processing returns to step S2, and a series of processing is repeated. Therefore, a series of processing of steps S2 to S5 causes the display unit 40 to display the load weight measured during the traveling of the vehicle.
[0036]
If it is determined in step S3 that the vehicle is stopped (Y in step S3), in step S7, a monitoring timer that times out after an arbitrarily determined monitoring time (for example, 20 minutes) elapses. It is started, and then, in step S8, the current frequency is set as the reference frequency of the RAM 33, and thereafter, the process proceeds to step S9. Note that the monitoring time can be set in units of one minute in a range of, for example, 10 to 60 minutes, and the time until the temperature difference is eliminated based on actual measurement data, experimental data, and the like is taken into consideration. It is preferable to set.
[0037]
In step S9, it is determined whether the monitoring timer has timed out. If it is determined that the monitoring timer has not timed out (N in step S9), in step S10, a difference between the previous frequency and the current frequency in the RAM 33 is calculated, and the difference is set as a frequency change amount. Whether or not the frequency has changed is determined based on whether or not the change amount is 0. If the frequency change amount is 0, that is, if it is determined that the frequency has not changed (N in step S10), the process proceeds to step S17 shown in FIG. If the frequency change amount is not 0, that is, if it is determined that the frequency has changed (Y in step S10), the process proceeds to step S11.
[0038]
In step S11, the current frequency is set to the previous frequency in the RAM 33. Thereafter, in step S12, the frequency change amount is compared with the determination information of the NVM 34, and based on the comparison result, it is determined whether the change is a change to be corrected. You. For example, it is determined whether or not the frequency change amount is less than 0.3 Hz. A change less than 0.3 Hz is caused by a temperature difference, and a change of 0.3 Hz or more is determined to be a change due to loading. Therefore, since the change due to the temperature difference and the change due to the loading (load) are detected in the determination processing in step S12, the determination process corresponds to a temperature difference detection unit described in the claims.
[0039]
If it is determined in step S12 that the change is a change to be corrected (Y in step S12), in step S13, a reference frequency is set to the measurement frequency of the RAM 33, and then the process proceeds to step S16 in FIG. Since the measured frequency is corrected by replacing the measured frequency with the reference frequency by this process, step S13 corresponds to a correcting unit described in claims.
[0040]
When it is determined in step S12 that the change is not a change to be corrected (N in step S12), that is, since a change due to loading is detected, the amount of frequency change is added to the reference frequency of the RAM 33 in step S14. The reference frequency is updated by the addition, and thereafter, in step S15, the current frequency is set as the measurement frequency of the RAM 33, and thereafter, the process proceeds to step S16.
[0041]
In step S16 shown in FIG. 4, similarly to step S5, when the loaded weight display process is executed, the loaded weight display process shown in FIG. 5 is called, and when the process returns from the loaded weight display process, the process proceeds to step S17. Then, by executing the loaded weight display processing, the loaded weight measured based on the measured frequency of the RAM 33 is displayed on the display unit 40. That is, the load weight displayed on the display unit 40 does not change when a change due to the temperature difference is detected, and is updated to the currently measured load weight when a change due to the temperature difference is detected.
[0042]
In step S17, as in step S3, it is determined whether the vehicle is stopped. If it is determined that the vehicle has not stopped, that is, it has been determined that the vehicle has restarted traveling (N in step S17), the process returns to step S2 shown in FIG. 3, and a series of processes is repeated. If it is determined that the vehicle is stopped (Y in step S17), the process proceeds to step S18.
[0043]
In step S18, as in step S2, when a timeout is notified from the measurement timer, each frequency is measured based on the pulse signal input from each sensing element 21, and these are stored in the RAM 33 as the current frequency, Thereafter, the process returns to step S9 shown in FIG. 3, and a series of processes is repeated.
[0044]
When it is determined in step S9 that the monitoring timer has timed out (Y in step S9), when the time-out is notified from the measurement timer in step S19 shown in FIG. Each frequency is measured based on the pulse signal, and these are stored in the RAM 33 as the measured frequency, and then the process proceeds to step S20.
[0045]
In step S20, similarly to step S5, when the loaded weight display process is executed, the loaded weight display process shown in FIG. 5 is called, and when the process returns from the loaded weight display process, the process proceeds to step S21. When the loaded weight display process is executed, the displayed weight of the stopped vehicle after the end of the monitoring period is displayed on the display unit 40 based on the measurement frequency of the RAM 33.
[0046]
In step S21, similarly to step S3, it is determined whether the vehicle is stopped. If it is determined that the vehicle is not stopped, that is, it is determined that the vehicle has restarted traveling (N in step S21), the process returns to step S2 shown in FIG. 3, and a series of processes is repeated. If it is determined that the vehicle is stopped (Y in step S21), the process returns to step S19, and a series of processes is repeated while the vehicle is stopped.
[0047]
Therefore, in the above-described embodiment, the CPU 31 of the loaded weight measuring device 30 according to the present invention functions as the start detecting unit, the temperature difference detecting unit, the correcting unit, and the loaded weight measuring unit described in the claims. ing.
[0048]
Next, an example of an operation (action) of the present embodiment of the loaded weight measuring device 20 to which the above-described sensor signal correction device according to the present invention is applied will be described with reference to the drawing of FIG. In FIG. 6, the vertical axis indicates the frequency of the pulse signal output from the sensing element 21, and the horizontal axis indicates time.
[0049]
When the vehicle travels for a long time and stops at time Ts, the frequency Fb measured based on the signal output from each sensing element 21 at that time Ts is stored in the NVM 34 as a reference frequency (reference value), and the monitoring timer starts from time Ts. The monitoring period is a time until the time Te at which the monitoring time elapses.
[0050]
As shown by the one-dot chain line in FIG. 6, the signal output from the sensing element 21 gradually increases due to the elapse of time after the stop, but the frequency measured for each of the measurement times during the monitoring period is a change to be corrected ( In the case of, for example, less than ± 0.3 Hz), the measured frequency is corrected to become the reference frequency Fb which is the frequency before the temperature difference occurs. Then, the output of the sensing element 21 rises to the frequency Fr (Fr> Fb), then gradually decreases as the temperature difference between the sensing element 21 and the axle decreases, and approaches the value indicated by the solid line in the figure.
[0051]
If the change in the frequency measured at each measurement time during the monitoring period is a change to be corrected, the frequency of the signal output from the sensing element 21 is corrected to the reference frequency Fb, as shown by the solid line in FIG. Then, the load weight corresponding to the reference frequency Fb is displayed on the display unit 40.
[0052]
Therefore, even if the signal output from the sensing element 21 during the monitoring period slightly increases to the frequency Fr due to a temperature difference between the sensing element 21 and the axle where the sensing element 21 is attached, the signal is corrected to the reference frequency Fb. Even if an error occurs in the output of the sensing element 21 due to a difference in the expansion amount due to the temperature difference, the output can be corrected to an appropriate output.
[0053]
Therefore, the accuracy of the signal output from the sensing element 21 can be improved without using a temperature sensor or the like. Further, by realizing the sensor signal correction device in the load weight measuring device 30, the influence of the temperature change of the sensor 21 can be eliminated, and the measurement can be performed based only on the load change, so that the accuracy of the load weight is improved. Can be done.
[0054]
By the end of the monitoring period, since the temperature difference between the sensing element 21 and the axle is eliminated, the error of the signal output from the sensing element 21 is reduced, and the error is eliminated after the end of the monitoring period. Therefore, there is no need to correct the frequency of the signal output from the sensing element 21 after the monitoring period. Therefore, after the monitoring period, the loaded weight may be measured based on the frequency of the signal output from each sensing element 21.
[0055]
Further, when a change in the load applied to the vehicle according to the load, unloading, etc. is detected during the monitoring period, the frequency of the signal output from the sensing element 21 corresponding to this detection is set as a new reference frequency. Even if loading and unloading operations are performed during the period, it is possible to eliminate an error generated in the signal of the sensor 21 due to the temperature difference and correct the signal to an accurate reference value.
[0056]
Further, since the monitoring period is started in response to the stop of the vehicle, the vehicle stops after running for a long time, and the temperature of the axle gradually rises, so that the sensing element 21 and the axle (attachment point) are connected. Even if an error occurs in the signal output from the sensing element 21, the error can be corrected. Therefore, even if the sensing element 21 is mounted on the axle, it is possible to eliminate a signal error due to a temperature difference generated after the vehicle stops.
[0057]
In the above-described embodiment, the case where the sensor signal correction device is applied to the loaded weight measuring device 30 and various means are realized by the CPU 31 and the NVM 34 of the loaded weight measuring device 30 has been described. However, the present invention is not limited to this, and various embodiments can be adopted such as implementing the sensor signal correction device as a correction circuit of a sensor unit having the sensing element 21.
[0058]
Further, in the above-described embodiment, a case has been described where the vehicle that has traveled for a long time stops and a temperature difference occurs between the sensing element 21 and the axle. However, the present invention is not limited to this. A temperature difference (temperature of the sensing element 21> temperature of the axle) occurs even immediately after the power is supplied to the power supply 21, so that an error in such a case can be corrected.
[0059]
【The invention's effect】
As described above, according to the sensor signal correction device of the present invention described in claim 1, it is determined whether or not a temperature difference has occurred between the sensor and the mounting position of the sensor in the vehicle based on the signal output from the sensor. When the occurrence of a temperature difference is detected during the monitoring period, the signal output from the sensor corresponds to the start of the monitoring period and is corrected so that the signal becomes the reference value before the temperature difference occurs. Therefore, even if a temperature difference occurs between the sensor and the mounting portion of the vehicle and a difference occurs in the amount of expansion due to the temperature difference and an error occurs in the output of the sensor, the output can be corrected to an appropriate output. Therefore, there is an effect that the accuracy of the signal output from the sensor can be improved without using a temperature sensor or the like.
[0060]
According to the second aspect of the invention, in addition to the effects of the first aspect, it is possible to determine a change due to a temperature difference and a change due to a load based on a signal output from the sensor and the determination information. From the above, by updating the reference value of the reference value storage means when a change in load is detected during the monitoring period, even if a load or unloading operation is performed during the monitoring period, a signal generated by the sensor due to a temperature difference is generated. The error can be eliminated and corrected to an accurate reference value. Therefore, even if unloading, loading, and the like occur during the monitoring period, the correction is performed based on the accurate reference value, so that the accuracy of the signal output from the sensor can be further improved.
[0061]
According to the invention described in claim 3, in addition to the effect of the invention described in claim 1 or 2, the monitoring period is started according to the stop of the vehicle, so that after the vehicle travels for a long time, If the temperature of the axle stops and the temperature of the axle gradually increases, a temperature difference occurs between the sensor and the vehicle-side sensor, and even if an error occurs in a signal output from the sensor, the error can be corrected. Therefore, if the ambient temperature changes, the axle and the sensor change at almost the same temperature, but since the axle of the vehicle that has traveled for a long time changes after stopping, a temperature difference is likely to occur between the axle and the sensor. Thus, even if a sensor is attached to the sensor, the signal can be accurately corrected.
[0062]
As described above, according to the loaded weight measuring device of the present invention, when the signal output from the sensor is corrected, the loaded weight is measured based on the correction result. Therefore, even if a temperature difference occurs between the sensor and the mounting location of the vehicle, it is possible to accurately measure the loaded weight. Therefore, since the influence of the temperature change of the sensor is excluded and the measurement is performed based only on the change in the load, there is an effect that the accuracy of the loaded weight can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a basic configuration of a sensor signal correction device and a loaded weight measurement device of the present invention.
FIG. 2 is a configuration diagram showing an example of a basic configuration of a loaded weight measuring device according to the present invention.
FIG. 3 is a flowchart showing a part of a processing outline executed by a CPU in FIG. 2;
FIG. 4 is a flowchart showing another part of the outline of the processing executed by the CPU in FIG. 2;
FIG. 5 is a flowchart illustrating an example of a loaded weight display process of FIGS. 3 and 4;
FIG. 6 is a diagram for explaining a correction example by the sensor signal correction device.
[Explanation of symbols]
21 Sensor (sensing element)
30 Loading weight measuring device
31a Start detection means (CPU)
31b Temperature difference detecting means (CPU)
31c Correction means (CPU)
31d Loading weight measuring means (CPU)
34a determination information storage means (NVM)
34b Reference value storage means (NVM)

Claims (4)

A sensor signal correction device that corrects a signal output from a sensor attached to the vehicle and that changes according to a load applied to the vehicle,
Based on a signal output by the sensor, a determination information storage unit that stores determination information for determining whether a temperature difference has occurred between the sensor and a mounting location of the sensor in the vehicle,
Start detection means for detecting the start of a monitoring period for monitoring the occurrence of the predetermined temperature difference;
Reference value storage means for storing a value corresponding to the signal output by the sensor corresponding to the start detected by the start detection means as a reference value,
Temperature difference detection means for detecting the occurrence of the temperature difference based on the signal output by the sensor during the monitoring period and the determination information stored in the determination information storage means,
When the temperature difference detection unit detects the occurrence of a temperature difference, a correction unit that corrects the signal corresponding to the detection to a reference value stored in the reference value storage unit,
A sensor signal correction device comprising: The determination information stored in the determination information storage means is configured to be able to determine a change due to the temperature difference and a change due to the load,
The temperature difference detection unit further detects a change in the signal due to the load based on a signal output by the sensor during the monitoring period and the determination information stored in the determination information storage unit.
2. The sensor according to claim 1, wherein when the temperature difference detection unit detects a change due to the load, the reference value storage unit sets a value corresponding to the signal corresponding to the detection as the reference value. 3. Signal correction device. The sensor is mounted on an axle of the vehicle,
The sensor signal correction device according to claim 1, wherein the start detection unit starts the monitoring when detecting a stop of the vehicle based on a traveling state signal indicating a traveling state of the vehicle. . A load weight measurement, comprising: a sensor attached to a vehicle for generating a signal that changes according to a load applied to the vehicle; and a load weight measurement unit for measuring a load weight of the vehicle based on a signal generated by the sensor. In the device,
The sensor signal correction device according to any one of claims 1 to 3, which performs correction on a signal output by the sensor,
The loaded weight measuring device is characterized in that when the correcting means makes a correction, the loaded weight measuring means performs the measurement based on the correction result corrected by the correcting means.

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