Acceleration sensor correction device, road gradient detection device, driving recorder, acceleration sensor correction program, and correction value data structure

Abstract

To provide an acceleration sensor correction device capable of suppressing the influence of zero point correction depending on the presence or absence of cargo, etc, a road gradient detection device, an operation record device, an acceleration sensor correction program, and a structure of correction value data.SOLUTION: An acceleration sensor correction device 100 includes: an acceleration sensor 14 mounted on a vehicle for detecting acceleration on a vehicle; a CPU1 that is configured to acquire information on road gradient at the current location, to perform zero correction of the acceleration sensor 14 based on the gradient information, to determine whether the vehicle is empty or full, and to perform zero correction of the acceleration sensor 14 based on the determination result by determining means after the zero correction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an acceleration sensor correction device that corrects an acceleration sensor used in a road gradient detection device that detects whether a vehicle is on a gradient, a road gradient detection device, a driving recorder, an acceleration sensor correction program, and a correction value data structure. [Background technology]

[0002] Conventionally, a vehicle operation control system that reflects road surface conditions such as slopes has been proposed (see Patent Document 1). The conventional operation control system described in Patent Document 1 measures air pressure using a barometer, calculates an altitude value for each unit travel distance from the air pressure, and compares the altitude difference for each unit travel distance with a predetermined altitude difference to determine whether the road surface on which the vehicle is traveling is sloped.

[0003] The invention described in Patent Document 1 determines the gradient using a barometer, but this requires a dedicated and expensive air pressure sensor and control circuit, and the accuracy deteriorates drastically in environments where the vehicle is subject to sudden changes in air pressure, such as when windows are opened or closed, when wind blows while driving, or when the environment changes suddenly.

[0004] Another known method for detecting gradients is to use an acceleration sensor. This method calculates the gradient of the road while traveling by calculating the tilt of the vehicle body detected by the acceleration sensor and the G (acceleration) value experienced while traveling. However, to ensure detection accuracy, it is important to correct the offset deviation (also called zero point correction) of the acceleration sensor.

[0005] In Patent Document 2, the output value α from the gradient vehicle acceleration sensor S and the theoretical free-running acceleration α0 calculated by the theoretical free-running acceleration calculation means, the correction value α of the gradient vehicle acceleration sensor output value is calculated. SD It is described that the following is calculated. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-46439 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-153883 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when performing zero-point correction, if the gradient at the point where the correction is performed is not zero (flat), the gradient at that point will directly become an error. Also, in the case of trucks and the like, there is a problem in that the difference in the inclination of the cabin (interior) due to the presence or absence of cargo will directly become an error.

[0008] The invention described in Patent Document 2 calculates the theoretical free-running acceleration α0 when it detects that the vehicle is in a free-running state on a flat road where power transmission between the engine and the wheels is cut off, but does not take into account the inclination of the cabin as described above.

[0009] In view of the above problems, the present invention aims to provide an acceleration sensor correction device, road gradient detection device, operation recording device, acceleration sensor correction program, and correction value data structure that can reduce the influence of factors such as the presence or absence of cargo when correcting the zero point. [Means for solving the problem]

[0010] The invention made to solve the above problem comprises an acceleration sensor mounted on a vehicle and detecting acceleration acting on the vehicle, a first acquisition means for acquiring gradient information indicating an actual gradient at a zero point correction execution point obtained by measurement, a second acquisition means for acquiring a table indicating the relationship between the actual gradient and a correction value, a first correction means for performing zero point correction of the acceleration sensor based on the table, a determination means for determining whether the vehicle is in an empty state or an occupied state, and a determination result of the determination means after the zero point correction by the first correction means. As a result and second correction means for performing zero point correction of the acceleration sensor based on the acceleration sensor value. [Effects of the Invention]

[0011] According to the present invention, it is possible to perform zero point correction suited to the state, whether the vehicle is empty or loaded, thereby reducing the influence of the presence or absence of a load on the zero point correction. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram illustrating the configuration of a road gradient detection device including an acceleration sensor correction device according to an embodiment of the present invention. [Figure 2] 10 is an example of a table showing the relationship between the gradient of an offset point and a correction value. [Figure 3] 2 is a schematic diagram of a correction operation performed by the acceleration sensor correction device shown in FIG. 1. [Figure 4] 2 is a schematic diagram of a correction operation performed by the acceleration sensor correction device shown in FIG. 1. [Figure 5] 2 is a flowchart of the operation of the acceleration sensor correction device shown in FIG. [Figure 6] 1 is a schematic configuration diagram of an operation recording device according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment of the present invention will now be described with reference to the drawings. Fig. 1 is a basic configuration diagram of a road gradient detection device 20 equipped with an acceleration sensor correction device according to an embodiment of the present invention. As shown in the figure, the road gradient detection device 20 includes a CPU 1, an EEPROM 2, an acceleration sensor 14, a power supply circuit 4, an IGN (ignition) 5, an input I / F circuit 6, output I / F circuits 8 and 9, dials 12 and 13, and a gradient information storage unit 15. The road gradient detection device 20 receives a vehicle speed pulse 7 and outputs an up-signal monitor 10 and a down-signal monitor 11.

[0014] An ON signal is input to CPU 1 from IGN (ignition) 5 via power supply circuit 4. When the vehicle starts running, a vehicle speed pulse 7 is supplied to CPU 1 via input I / F circuit 6. When CPU 1 determines that the road surface on which the vehicle is running is a slope, it outputs a slope signal as an up signal monitor 10 and a down signal monitor 11 via output I / F circuits 8 and 9. CPU 1 also performs zero point correction processing for acceleration sensor 14, which will be described later.

[0015] The EEPROM 2 has a program storage area that stores processing programs executed by the CPU 1, a work area used in various processing steps in the CPU 1, and a data storage area that stores various data, and is provided so that it can be read and written freely.

[0016] The acceleration sensor 14 measures (detects) the acceleration acting on the vehicle, for example, in the traveling direction, and the inclination of the vehicle itself.

[0017] The dials 12 and 13 set a threshold value for determining whether the road surface on which the vehicle is traveling is a slope (gradient) or not. In this embodiment, the threshold value is set to, for example, 2.5%.

[0018] The gradient information storage unit 15 stores the relationship between the gradient and the correction value. The gradient information stored in this gradient information storage unit 15 is registered as the accurate gradient value measured with a level and the correction value corresponding to that gradient. The gradient information may be registered as the raw measured value, or the relationship between the measurement and the correction value may be registered as a map, table, or the like. An example of a table is shown in FIG. 2.

[0019] Fig. 2 is an example of a table showing the relationship between gradient (%) and correction value. In Fig. 2, the gradient is divided into 0.5% increments and correction values ​​are set, but the gradient may be further divided into smaller increments. That is, the table shown in Fig. 2 is a correction value data structure according to this embodiment, and the gradient information is a table of correction value information for each gradient value used when performing zero point correction processing of the acceleration sensor depending on whether the vehicle is in an empty state or an occupied state, as will be described later.

[0020] In this embodiment, a gradient of zero (flat) does not only mean completely flat zero degrees or zero percent, but also includes a gradient of a degree that can be regarded as flat and calculated when correcting the acceleration sensor 14, which will be described later, for example, within 0±0.5%.

[0021] In this embodiment, the gradient information is stored in advance in the actual gradient information storage unit 15, but it may be configured to be downloaded from an external server, for example.

[0022] In the above-described configuration, the CPU 1, the acceleration sensor 14, and the gradient information storage unit 15 constitute an acceleration sensor correction device 100 according to one embodiment of the present invention.

[0023] In this embodiment, the actual gradient at the point where zero point correction processing is performed (offset point) is measured with a level, and correction is performed based on the measurement value (Figure 3). It is preferable to perform zero point correction processing on a flat road, but even on roads and points that are considered to be flat, the actual gradient may not necessarily be zero. Therefore, in order to perform accurate zero point correction processing, the actual gradient is measured and correction is performed according to the measurement value.

[0024] In addition to the correction based on the actual gradient, in this embodiment, a determination is made as to whether the vehicle is empty (state) or occupied (state), and the inclination difference is corrected according to whether the vehicle is empty or occupied (Fig. 4). As shown in Fig. 4, for example, in the case of a truck, if there is cargo in the trunk, the cabin in which the acceleration sensor 14 and other components are installed will tilt, causing an error during zero point correction. Therefore, a determination is made as to whether the vehicle is empty or occupied, to identify whether there is cargo, and a correction appropriate for each state is made.

[0025] Next, the operation of the acceleration sensor correction device 100 configured as described above will be described with reference to the flowchart in Fig. 5. The flowchart shown in Fig. 5 is executed by CPU 1. Furthermore, the flowchart in Fig. 5 can be configured as a computer program executed by CPU 1, for example, to create an acceleration sensor correction program.

[0026] First, CPU 1 reflects gradient information at the offset point (step S11). In step S11, the actual gradient of the road surface at the current location (offset point) is measured using a spirit level, and based on the measurement results, a correction value is obtained using the table shown in FIG. 2 to perform zero point correction processing. The correction processing itself may be a well-known zero point correction method such as adding or subtracting a correction value from the output value of acceleration sensor 14. In other words, CPU 1 functions as first acquisition means that acquires gradient information at the current location and first correction means that performs zero point correction based on the gradient information. CPU 1 also functions as second acquisition means that acquires a table showing the relationship between gradient and correction value.

[0027] Next, CPU 1 determines whether the vehicle is one for which cabin tilt difference correction is to be performed (step S12). That is, the determination is made if the vehicle type is one for which determination of an empty state or an occupied state is to be performed. Whether the vehicle is one for which cabin tilt difference correction is to be performed can be determined by setting a flag, a setting value, or the like in advance, and by referring to the setting value, or the like. Vehicles for which cabin tilt difference correction is to be performed are, for example, trucks, minivans, vans, buses, and other vehicles primarily for commercial use that are equipped with an operation management device, and in which a difference in cabin tilt occurs depending on the presence or absence of heavy objects other than the driver, such as cargo, and the detection value of acceleration sensor 14 is affected.

[0028] Note that step S12 and subsequent steps may be performed at a different location from step S11, provided that they are performed at a location after step S11. Step S11 is performed while the vehicle is stationary in order to measure using a spirit level placed on the road surface as described above, but step S12 and subsequent steps may be performed while the vehicle is moving, as will be apparent from the following explanation. Therefore, step S11 and step S12 and subsequent steps may be performed independently.

[0029] If the vehicle is one for which cabin tilt difference correction is to be performed (step S12; Y), the CPU 1 determines whether the vehicle is empty (step S13). The empty state determination can be performed, for example, in conjunction with an empty / occupied switch on a digital tachograph (operation recording device). In other words, the acceleration sensor correction device 100 can obtain a switching signal or the like in response to the operation of a switch for switching between empty and occupied status provided on the digital tachograph, and make a determination. Of course, the acceleration sensor correction device 100 may have input means, and the driver or the like may input whether the vehicle is empty or occupied through the input means. In other words, the determination means makes the determination by obtaining information indicating the vehicle's empty or occupied status.

[0030] In this embodiment, an empty vehicle refers to a state in which there are no heavy items such as cargo (passengers in the case of a bus, etc.) loaded in the luggage compartment, and a loaded vehicle refers to a state in which there are heavy items such as cargo loaded in the luggage compartment.

[0031] Furthermore, the determination of the empty vehicle state is not limited to the above-mentioned method linked to a digital tachograph or a method directly input by the driver, etc. For example, since the vibration state of the cabin (interior) of a vehicle changes depending on whether it is empty or occupied, a method of determining whether the vehicle is empty or occupied may be used. The reference point may be a point that the vehicle normally passes through during operation, such as a point on a road facing a company's entrance / exit gate. The specific condition may be, for example, a traveling speed that is a predetermined value. The vibration pattern (output waveform of the acceleration sensor 14) when the vehicle passes through a reference point under specific conditions is measured in advance, and the vibration pattern is compared with the vibration pattern during actual driving to determine the empty / occupied state.

[0032] If step S13 determines that the vehicle is empty (step S13; Y), an inclination correction process (zero point correction process) is performed by referring to a previously determined empty vehicle equivalent value (correction value) (step S14). The previously determined empty vehicle equivalent value is a correction value for the inclination state of the cabin when the vehicle is empty. When the vehicle is empty, the cabin hardly inclines, but by measuring it in advance as a reference value, the accuracy of the zero point correction can be improved. Note that the correction process itself in steps S13 and S14 can be a well-known method, as in step S11.

[0033] On the other hand, if it is determined in step S13 that the vehicle is not empty (actual vehicle state) (step S13; N), tilt correction processing (zero point correction processing) is performed by referring to a previously determined actual vehicle equivalent value (correction value) (step S15). The previously determined actual vehicle equivalent value is a correction value for the cabin tilt state when the vehicle is actually in motion. In this case, the correction value corresponding to the tilt value can be obtained from the table of FIG. 2 used in step S11. In other words, the zero point correction processing can be performed by obtaining a correction value corresponding to the cabin tilt value (%) from the table. The cabin tilt value can be obtained from an inclinometer or the like installed in the cabin.

[0034] Also, if it is determined in step S12 that the vehicle does not require cabin tilt difference correction (step S12; N), the process ends without executing the processing from step S13 onwards.

[0035] As is clear from the description of steps S13 to S15, CPU 1 functions as a determination means for determining whether the vehicle is in an empty state or an occupied state, and also functions as a second correction means for performing zero point correction of acceleration sensor 14 based on the determination result of the determination means after the zero point correction by the first correction means.

[0036] After the execution of the above-described flowchart, the process may return to the well-known slope detection process using the acceleration sensor 14. The well-known slope detection process using the acceleration sensor 14 may involve, for example, the CPU 1 subtracting a value corresponding to the actual acceleration obtained from the detected vehicle speed based on the vehicle speed pulse 7 from the output value of the acceleration sensor 14 while the vehicle is traveling, and detecting the road gradient from the output of the acceleration sensor 14 after the subtraction. Furthermore, when detecting the road gradient, a threshold value set by the dials 12 and 13 may be used to determine whether or not there is a gradient. In other words, the CPU 1 functions as a road gradient detection unit.

[0037] According to this embodiment, the acceleration sensor correction device 100 is equipped with an acceleration sensor 14 that is mounted on a vehicle and detects the acceleration acting on the vehicle, and a CPU 1 that determines whether the vehicle is in an empty state or an occupied state and performs zero point correction of the acceleration sensor 14 based on the determination result.

[0038] The acceleration sensor correction device 100 configured as described above can perform zero point correction appropriate for either the empty vehicle state or the loaded vehicle state, thereby reducing the influence of the presence or absence of a load on the zero point correction.

[0039] Furthermore, before determining whether the vehicle is in an empty or occupied state, the CPU 1 acquires gradient information about the current location and performs zero point correction based on the gradient information, separate from the zero point correction performed in step S13 or S14. This reduces errors due to the inclination of the terrain at the current location and the zero point deviation of the acceleration sensor 14.

[0040] Furthermore, the CPU 1 acquires a table showing the relationship between gradient information measured by a measuring instrument such as a level and its correction value, and performs zero point correction based on the table. By doing so, it is possible to use pre-calculated correction values, thereby reducing the correction processing load.

[0041] Furthermore, the CPU 1 may determine whether the vehicle is in an empty or occupied state based on the vibration pattern detected by the acceleration sensor at a preset reference point. In this case, the determination can be made automatically without the driver or other person having to input the empty or occupied state.

[0042] Furthermore, the CPU 1 determines whether the vehicle is in an empty or occupied state by acquiring information indicating the vehicle's empty or occupied state, so that the CPU 1 can reliably determine whether the vehicle is in an empty or occupied state.

[0043] Furthermore, the CPU 1 determines whether the vehicle is in an empty state or an occupied state when the vehicle is one for which cabin tilt difference correction is to be performed, and therefore does not need to determine whether the vehicle is in an empty state or an occupied state for vehicles for which cabin tilt difference correction is not required, thereby enabling efficient processing.

[0044] Furthermore, since the road gradient detection device 20 is equipped with the acceleration sensor correction device 100 configured as described above, it is possible to suppress a decrease in the detection accuracy of the acceleration sensor, which is one of the factors that reduces the detection accuracy of road gradients. Furthermore, when it is necessary to correct the cabin tilt, zero point correction is performed using a correction value that suits the state of either an empty vehicle or an occupied vehicle, so it is possible to suppress the influence of the presence or absence of a load, etc., on the zero point correction.

[0045] The road gradient detection device 20 described in the above embodiment may also be provided in a vehicle operation recording device. An example in which the road gradient detection device 20 is provided in an operation recording device is shown in Fig. 6. Fig. 6 is a schematic configuration diagram of an operation recording device 200 equipped with the road gradient detection device 20. The operation recording device 200 is also called a digital tachograph, and sequentially records driving information such as vehicle speed and engine RPM, and information related to operation conditions such as entering and leaving a parking lot, along with the time of occurrence.

[0046] The operation recording device 200 includes a road gradient detection device 20 and an operation recording unit 201. The operation recording unit 201 collects various operation information such as the vehicle speed, engine RPM, entering and leaving the vehicle, and records the information in an SD card 202. Note that the information need not necessarily be recorded in the SD card, but may also be transmitted to an external server or the like.

[0047] 6 is equipped with the road gradient detection device 20, it is possible to acquire gradient information detected with high accuracy. Therefore, it is possible to associate whether or not the vehicle is traveling on a slope with the traveling information, and it is possible to perform appropriate operation management that reflects the traveling state.

[0048] Furthermore, the present invention is not limited to the above-described embodiments. In other words, those skilled in the art can implement various modifications in accordance with conventionally known knowledge without departing from the gist of the present invention. Even with such modifications, as long as the acceleration sensor correction device, road gradient detection device, operation recording device, acceleration sensor correction program, and correction value data structure of the present invention are still included within the scope of the present invention. [Explanation of symbols]

[0049] 1 CPU (determination means, first correction means, first acquisition means, second correction means, second acquisition means) 7 Vehicle speed pulse 14 Acceleration sensor 15 Gradient information storage unit (storage unit) 20 Road gradient detection device 100 Acceleration sensor correction device 200 Operation Recording Device

Claims

1. an acceleration sensor mounted on a vehicle to detect acceleration acting on the vehicle; A first acquisition method for acquiring gradient information indicating the actual gradient at the zero point correction execution point obtained by measurement. Step by step, a second acquisition means for acquiring a table showing the relationship between the actual gradient and the correction value; a first correction means for performing zero point correction of the acceleration sensor based on the table; a determination means for determining whether the vehicle is in an empty state or an occupied state; a second correction means for performing a zero point correction of the acceleration sensor based on a determination result of the determination means after the zero point correction by the first correction means; An acceleration sensor correction device comprising:

2. 2. The acceleration sensor correction device according to claim 1, wherein the determining means makes a determination based on a vibration pattern detected by the acceleration sensor at a preset reference point.

3. 2. The acceleration sensor correction device according to claim 1, wherein the determining means makes the determination by acquiring information indicating the empty state or the occupied state of the vehicle.

4. an acceleration sensor mounted on a vehicle to detect acceleration acting on the vehicle; a first acquisition means for acquiring gradient information indicating an actual gradient at a zero point correction execution point obtained by measurement; a second acquisition means for acquiring a table showing the relationship between the actual gradient and the correction value; a first correction means for performing zero point correction of the acceleration sensor based on the table; a confirmation means for confirming whether or not the type of the vehicle is a target for execution of a preset determination after the zero point correction by the first correction means; a determination means for determining whether the vehicle is in an empty state or an occupied state when the type is the execution target; a second correction means for performing zero point correction of the acceleration sensor based on the determination result of the determination means; An acceleration sensor correction device comprising:

5. 5. A road gradient detection device comprising: a road gradient detection unit that detects the gradient of a road on which the vehicle is located based on the acceleration detected by the acceleration sensor corrected by the acceleration sensor correction device according to claim 1.

6. 6. A driving recorder for collecting driving information of the vehicle, comprising the road gradient detection device according to claim 5.

7. An acceleration sensor correction program for performing zero point correction of an acceleration sensor mounted on a vehicle and detecting acceleration acting on the vehicle, a first acquisition means for acquiring gradient information indicating an actual gradient at a zero point correction execution point obtained by measurement; a second acquisition means for acquiring a table showing the relationship between the actual gradient and the correction value; a first correction means for performing zero point correction of the acceleration sensor based on the table; a determination means for determining whether the vehicle is in an empty state or an occupied state by externally acquiring information indicating the vehicle's empty state or occupied state; a second correction means for performing a zero point correction of the acceleration sensor based on a determination result of the determination means after the zero point correction by the first correction means; and causing a computer to function as an acceleration sensor correction program.

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