Acceleration sensor correction device, road gradient detection device, and driving recorder

Abstract

To provide an acceleration sensor correction device, a road gradient detector, and an operation recorder that can more accurately correct the gradient detection based on an acceleration.SOLUTION: An acceleration sensor correction device 100 is boarded on a vehicle, comprising: an acceleration sensor 14 for detecting an acceleration applied to the vehicle; a wireless communication unit 3 for receiving information about an atmospheric pressure detected in the vehicle; and a CPU1 which determines whether or not the atmospheric pressure information can be received by the wireless communication unit 3, which determines, when the information can be received, whether or not a road on which an own vehicle is running is flat based on the atmospheric pressure information received by the wireless communication unit 3, and which performs, when it is determined that the road is flat, a zero-point correction of the acceleration sensor 14.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 located on a gradient, a road gradient detection device, and a driving recorder. [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 or not.

[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 subject to sudden changes in air pressure, such as when windows are opened and closed, when wind blows while driving, or when the environment changes suddenly.

[0004] There is also a known method for detecting gradients that uses an acceleration sensor. This method calculates the gradient of the road on which the vehicle is traveling by calculating the inclination of the vehicle body detected by the acceleration sensor and the G (acceleration) value received while traveling. However, to ensure detection accuracy, it is important to correct the offset deviation of the acceleration sensor (also called zero point correction).

[0005] Patent Document 2 describes that a gradient detection unit corrects the zero point of the G-sensor acceleration based on the change in G-sensor acceleration during a vehicle attitude learning period from door opening detection to door closing detection, according to the vehicle attitude that changes based on people and objects getting on and off. Patent Document 2 also describes that when constant speed driving on a flat road is detected, the gradient detection unit further corrects the zero point of the G-sensor acceleration based on the difference between the actual acceleration during constant speed driving on a flat road and the G-sensor acceleration. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2004-46439 A [Patent Document 2] JP 2010-107244 A Summary of the Invention [Problem to be solved by the invention]

[0007] The invention described in Patent Document 2 describes applying zero point correction to the G sensor acceleration in accordance with the vehicle attitude that changes based on people and objects getting on and off, but the places where people and objects get on and off are not always flat. For example, the vehicle attitude while stopped may differ between a sloping road such as a slope and a flat road, which may reduce the accuracy of the zero point correction.

[0008] In view of the above-mentioned problems, an object of the present invention is to provide an acceleration sensor correction device, a road gradient detection device, and a driving recorder that can correct gradient detection based on acceleration with higher accuracy. [Means for solving the problem]

[0009] The invention made to solve the above problem is an acceleration sensor correction device comprising: an acceleration sensor mounted on a vehicle and detecting acceleration applied to the vehicle; a first determination means for determining whether atmospheric pressure information detected within the vehicle can be received; a receiving means for receiving the atmospheric pressure information when it is determined that the atmospheric pressure information can be received; a second determination means for determining whether the road on which the vehicle is located is flat based on the atmospheric pressure information; and a correction means for performing zero point correction of the acceleration sensor when it is determined that the road is flat. Effect of the Invention

[0010] As described above, according to the present invention, when atmospheric pressure information is available, it is determined whether the road on which the vehicle is located is flat based on the atmospheric pressure information, and if the road is flat, zero point correction is performed, so that zero point correction can be performed reliably on a flat place, and thus gradient detection based on acceleration can be made more accurately. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram of a road gradient detection device including an acceleration sensor correction device according to an embodiment of the present invention; [Diagram 2] 4 is a flowchart of the operation of the acceleration sensor correction device shown in FIG. [Diagram 3] 1 is a schematic configuration diagram of a driving recorder according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] An embodiment of the present invention will be described below 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, a wireless communication unit 3, 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 map 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.

[0013] An ON signal is input to the CPU 1 from an IGN (ignition) 5 via a power supply circuit 4. When the vehicle starts to travel, a vehicle speed pulse 7 is supplied to the CPU 1 via an input I / F circuit 6. When the CPU 1 determines that the road surface on which the vehicle is traveling is a slope, the CPU 1 outputs a slope signal as an uphill signal monitor 10 and a downhill signal monitor 11 via output I / F circuits 8 and 9. The CPU 1 also performs zero point correction processing for an acceleration sensor 14, which will be described later.

[0014] The EEPROM 2 has a program storage area for storing processing programs executed by the CPU 1, a work area used in various processing steps in the CPU 1, and a data storage area for storing various data, and is provided so as to be freely readable and writable.

[0015] The wireless communication unit 3 wirelessly communicates with an information communication terminal 30 disposed outside the road gradient detection device 20. The wireless communication unit 3 acquires atmospheric pressure information from the information communication terminal 30. Note that, although the wireless communication unit 3 is connected to the information communication terminal 30 wirelessly in this embodiment, it may be connected by wire, for example, via a Universal Serial Bus (USB). That is, the wireless communication unit 3 functions as a receiving means for receiving atmospheric pressure information.

[0016] The acceleration sensor 14 measures (detects) the acceleration applied to 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 map information storage unit 15 stores map information such as road map data for the whole of Japan, facility data for various facilities associated with the road map data, and data for map matching. The road map data is provided as link data, which is made up of a road network in which roads on a map are represented by lines, and in which intersections, branching points, and the like are divided into a plurality of parts as nodes, and the parts between the nodes are defined as links. This link data includes data such as a link ID unique to the link, the link length, position data (longitude, latitude) of the start point and end point (node) of the link, angle (direction) data, road width, road type, and road attributes.

[0019] In addition, information (zero gradient information) indicating roads and points with zero gradient (flat roads) is added to the road map data. This zero gradient information corresponds to flat land information. Furthermore, the points indicated by the zero gradient information are not limited to roads, but may include points where vehicles can pass, such as parking lots. This zero gradient information may be included not only in the road map data, but also in facility data such as parking lots. Furthermore, it is preferable to investigate and set accurate zero gradient points using a spirit level or the like. Note that the zero gradient (flat) in this embodiment does not only refer to completely flat zero degrees or zero%, but also includes a gradient that can be calculated as flat when correcting the acceleration sensor 14 described later, such as within 0±0.5%.

[0020] In this embodiment, map information is stored in advance in the map information storage unit 15, but it may be configured to download map information from an external server or the like, or the map information of the car navigation device may include flat land information and the map information may be acquired from the car navigation device. Alternatively, the map information storage unit 15 may not be provided, and information consisting only of latitude and longitude information of zero-gradient points may be generated (acquired) as zero-gradient information (flat land information). Such zero-gradient information may be obtained by conducting a preliminary survey of roads that are normally used in operation, such as roads at the entrance and exit of a company's warehouse or bridges.

[0021] The information communication terminal 30 is configured, for example, by a smartphone or a tablet terminal. The information communication terminal 30 has built-in devices and circuits capable of measuring atmospheric pressure, such as an atmospheric pressure sensor. The information communication terminal 30 transmits the atmospheric pressure information measured by itself to the wireless communication unit 3. The information communication terminal 30 is disposed in a vehicle in which the road gradient detection device 20 is installed. This disposition is not limited to being fixed in the vehicle, but also includes, for example, being placed on a seat. Even if the information communication terminal 30 is fixed, it may be detachable so that it can be taken out of the vehicle.

[0022] The information communication terminal 30 does not have to be a terminal specialized for measuring atmospheric pressure, such as a smartphone, as described above. If a barometer is installed in the vehicle, however, atmospheric pressure information may be obtained from the barometer.

[0023] In the above-mentioned configuration, the CPU 1, the wireless communication unit 3, the acceleration sensor 14, and the map information storage unit 15 constitute an acceleration sensor correction device 100 according to one embodiment of the present invention.

[0024] Next, the operation of the acceleration sensor correction device 100 having the above-mentioned configuration will be described with reference to the flowchart of Fig. 2. The flowchart shown in Fig. 2 is executed by the CPU 1.

[0025] First, the CPU 1 performs zero offset processing (zero point correction processing) of the acceleration sensor 14 (step S11). The zero point correction processing in this step may be a well-known method of storing the output of the acceleration sensor 14 at the point where the gradient is zero as the output of the acceleration sensor at the gradient zero point. It is preferable to execute step S11 by investigating the accurate gradient zero point using a spirit level or the like. The corrected result (such as a voltage value corresponding to the zero point) is stored in, for example, the EEPROM 2 or the like.

[0026] Next, the CPU 1 determines whether atmospheric pressure information inside the vehicle can be obtained (step S12). That is, the CPU 1 functions as a first determination means for determining whether atmospheric pressure information measured (detected) inside the vehicle can be received. In step S12, it is determined whether the information communication terminal 30 is placed inside the vehicle (presence or absence). The presence or absence of the information communication terminal 30 can be determined by pairing the road gradient detection device 20 and the information communication terminal 30 in advance using, for example, Bluetooth (registered trademark) or the like, and if the paired information communication terminal 30 is detected, it can be determined that the information communication terminal 30 is present, that is, that atmospheric pressure information can be obtained inside the vehicle. In the case of a wired connection, the presence or absence of the wired connection can be detected.

[0027] If atmospheric pressure information can be acquired inside the vehicle (step S12; Y), the CPU 1 determines whether there is no change in atmospheric pressure during driving or whether it is within a specified range based on the acquired atmospheric pressure information (step S13). In step S13, a flat road is determined based on the atmospheric pressure information. The specified range indicates the range of change in atmospheric pressure that can be determined to be flat, and may be set appropriately. That is, the CPU 1 determines whether the road on which the vehicle is located is flat or not based on the atmospheric pressure information.

[0028] If it is not possible to obtain air pressure information inside the vehicle (step S12; N), or if the air pressure has changed during driving or is outside a specified range (step S13; N), the CPU 1 judges whether the vehicle is passing through a road or point with a zero gradient based on the map information stored in the map information storage unit 15 (step S14). If the judgment in step S13 is N, this means that there is no air pressure sensor, or that the air pressure sensor is not good at detecting elevation differences due to gradients or air pressure fluctuations, and is not suitable for detecting flat roads, so flat roads are detected by another means.

[0029] In step S14, the zero gradient information included in the map information is referenced to determine whether the current position acquired from a current position acquisition means (not shown) such as a GPS (Global Positioning System) is traveling on a zero gradient road or point. That is, when it is determined that the atmospheric pressure information cannot be received, the CPU 1 determines whether the road on which the vehicle is located is flat or not based on the flat ground information included in the map information. This method can also be used to make a similar determination using a GPS or the like when using independent flat ground information not included in the map information described above.

[0030] If there is no change in atmospheric pressure during driving or if it is within a specified range (step S13; Y), or if the vehicle is passing a road or point with a zero gradient (step S14; Y), the CPU 1 determines that the vehicle is driving on a flat road and performs additional correction processing for the acceleration sensor 14 (step S15). That is, the CPU 1 functions as a correction means for performing zero point correction of the acceleration sensor when it is determined that the road is flat.

[0031] The additional correction process in step S15 may be a well-known method of, for example, comparing the acceleration detected by the acceleration sensor 14 with the acceleration (actual acceleration) calculated from the time change in the detected vehicle speed based on the vehicle speed pulse 7, and correcting the zero point of the acceleration sensor 14 according to the difference (deviation) between the detected value of the acceleration sensor 14 and the actual acceleration. The corrected result (such as a voltage value corresponding to the zero point) is stored in, for example, the EEPROM 2.

[0032] After the additional correction process in step S15 is completed, or if the vehicle is not passing through a zero-gradient road / point (step S14; N), the CPU 1 returns to the normal slope detection process using the acceleration sensor 14 (step S16).

[0033] A slope detection process using a normal acceleration sensor 14 may be performed by using a well-known method, such as that described in Patent Document 2, in which a value corresponding to the actual acceleration obtained from the detected vehicle speed based on the vehicle speed pulse 7 while the vehicle 1 is traveling is subtracted from the output value of the acceleration sensor 14, and the road gradient is detected from the output of the acceleration sensor 14 after the subtraction. In addition, 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.

[0034] If the result of the determination in step S14 is that the vehicle is not passing through a zero-gradient road / point (step S14; N), the CPU 1 may issue a warning to perform a correction process of the acceleration sensor 14 taking into account the ambient temperature and changes over time before returning to the slope detection process in step S16. If the determination in step S14 is N, no additional correction process is performed, but since the correction result performed in step S11 is used, at least a decrease in detection accuracy is suppressed. However, it is known that the output of the acceleration sensor 14 varies depending on the ambient temperature and the results over time, and the detection accuracy of the acceleration sensor 14 can be improved by taking these factors into account.

[0035] The warning may be, for example, a warning sound or a warning message output from a speaker (not shown) or displayed by an indicator (not shown). The speaker, indicator, etc. serve as warning means. It is preferable that the driver or the like who receives the warning promptly executes the zero point correction process in step S11 (or the additional correction process in step S15).

[0036] Specifically, the ambient temperature of the acceleration sensor 14 can be detected by adding a temperature detection means such as a temperature sensor, and if the CPU 1 determines that the temperature is outside a predetermined temperature range (outside the predetermined range), a warning can be issued. In other words, a warning is issued if the ambient temperature is too high or too low. As for changes over time, a time detection means such as a timer or clock function built into the CPU 1 can be added to measure time, and a warning can be issued when a certain amount of time has passed since the previous zero point correction process. For example, at the same time as the warning, flat roads (roads / points with zero gradients) close to the current location can be displayed on a display device or the like based on map information.

[0037] According to this embodiment, the acceleration sensor correction device 100 is equipped with an acceleration sensor 14 mounted on a vehicle for detecting acceleration acting on the vehicle, and a wireless communication unit 3 for receiving atmospheric pressure information detected inside the vehicle. The acceleration sensor correction device 100 further includes a CPU 1 that determines whether atmospheric pressure information can be received by the wireless communication unit 3, and if so, determines whether the road on which the vehicle is located is flat based on the atmospheric pressure information received by the wireless communication unit 3, and performs zero point correction of the acceleration sensor 14 if it is determined that the road is flat.

[0038] By configuring the acceleration sensor correction device 100 as described above, it is possible to determine whether the road on which the vehicle is located is flat based on the atmospheric pressure information, and perform zero point correction if the road is flat, so that the zero point correction can be performed reliably on a flat place. Therefore, it is possible to more accurately detect gradient based on acceleration. In addition, since the atmospheric pressure information is only used to detect a flat road, an atmospheric pressure sensor included in an external device such as the information communication terminal 30 may be used instead of a dedicated atmospheric pressure sensor.

[0039] Moreover, the wireless communication unit 3 receives atmospheric pressure information via wireless communication from an information communication terminal 30 having an atmospheric pressure sensor arranged inside the vehicle. In this way, a device equipped with an atmospheric pressure sensor can be used, and since there is no need to install a dedicated expensive atmospheric pressure sensor, costs can be reduced.

[0040] The vehicle also includes a map information storage unit 15 that stores map information including zero gradient information, and the CPU 1 determines whether the road on which the vehicle is located is flat or not based on the zero gradient information included in the map information when the wireless communication unit 3 cannot receive atmospheric pressure information. In this way, even when atmospheric pressure information cannot be received, a flat road or the like can be identified based on the map information, and zero point correction can be performed on the identified flat road.

[0041] Furthermore, since the road gradient detection device 20 includes 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 causes a decrease in the detection accuracy of the road gradient. Furthermore, since zero point correction is performed when a flat road or the like is detected, it is possible to perform accurate gradient detection even when using an inexpensive acceleration sensor that is not highly accurate.

[0042] The road gradient detection device 20 described in the above embodiment may 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. 3. Fig. 3 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 the vehicle together with the time of occurrence.

[0043] 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 above-mentioned vehicle speed, engine RPM, entering and leaving the garage, and records it in an SD card 202. Note that the various information may not only be recorded in the SD card, but may also be transmitted to an external server or the like.

[0044] 3, the road gradient detection device 200 is equipped with the road gradient detection device 20, and therefore gradient information detected with high accuracy can be acquired. Therefore, it becomes possible to associate whether or not the vehicle is traveling on a slope with the traveling information, and appropriate operation management that reflects the traveling state can be performed.

[0045] Furthermore, the present invention is not limited to the above-mentioned embodiment. In other words, a person skilled in the art can implement various modifications according to the conventionally known knowledge without departing from the gist of the present invention. As long as such modifications still include the configuration of the acceleration sensor correction device, road gradient detection device, and driving recorder of the present invention, they are of course included in the scope of the present invention. [Explanation of symbols]

[0046] 1 CPU (first determination means, second determination means, correction means, road gradient detection unit) 3 Wireless communication unit (receiving means) 7 Vehicle speed pulse 14 Acceleration Sensor 15 Map information storage unit (acquisition means) 20 Road gradient detector 30 Information and communication terminals 100 Acceleration sensor correction device 200 Driving recorder

Claims

1. An acceleration sensor mounted on a vehicle to detect acceleration acting on the vehicle; a first determination means for determining whether atmospheric pressure information measured inside the vehicle can be received; a receiving means for receiving the atmospheric pressure information when it is determined that the atmospheric pressure information can be received; a second determination means for determining whether or not a road on which the vehicle is located is flat based on the atmospheric pressure information; a correction means for performing a zero point correction of the acceleration sensor when the road is determined to be flat; Equipped with The acceleration sensor correction device according to claim 1, wherein the receiving means receives the atmospheric pressure information by communication from an information communication terminal having an atmospheric pressure sensor arranged inside the vehicle.

2. An acquisition means for acquiring flat ground information, the second determination means, when it is determined that the atmospheric pressure information cannot be received, determines whether or not a road on which the vehicle is located is flat based on the flat ground information.

2. The acceleration sensor correction device according to claim 1,

3. An acceleration sensor correction device according to claim 1 or 2, a road gradient detection unit that detects a gradient of a road on which the vehicle is located based on the acceleration detected by the acceleration sensor; A road gradient detection device comprising:

4. 4. A driving recorder comprising the road gradient detection device according to claim 3 and which collects driving information of the vehicle.

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