In-vehicle device and program

Abstract

To accurately determine whether a road is an uphill or downhill slope without requiring complex processing, even when zero point correction of an acceleration sensor cannot be performed under ideal conditions. [Solution] The on-board device is equipped with a slope detection function that calculates a gradient value based on the vehicle acceleration measured by an acceleration sensor and determines whether the vehicle is on a slope by comparing it with thresholds S0 and S1, and is equipped with a counting unit that counts the number of uphill and downhill judgments for each vehicle trip, and a threshold correction unit that corrects the thresholds S0 and S1 based on the number of uphill and downhill judgments counted by the counting unit, and the threshold correction unit calculates the rate of agreement between the outbound trajectory and the return trajectory for each vehicle trip, and weights the number of uphill and downhill judgments for each vehicle trip counted by the counting unit so that the higher the rate of agreement, the greater the weighting, and corrects the thresholds S0 and S1 based on the ratio X of the number of uphill and downhill judgments over multiple vehicle trips.

Description

[Technical Field]

[0001] The present invention relates to an in-vehicle device and a program. [Background technology]

[0002] A known in-vehicle device equipped with a road gradient detection function using an acceleration sensor is one that suppresses the issuance of an engine over-rev warning when it determines that the road is on a slope based on the detected road gradient (see, for example, Patent Document 1). Another known in-vehicle device equipped with a road gradient detection function using an acceleration sensor is one that has a zero point correction function for the acceleration sensor (see, for example, Patent Document 2). Patent Document 2 describes a method of measuring the actual gradient at a point where zero point correction processing of the acceleration sensor is performed using a level, and performing zero point correction according to the actual gradient using a table that shows the relationship between the zero point correction value and the actual gradient.

[0003] Another known method for calibrating an acceleration sensor provided in an on-board device is to correct the measurement value of the acceleration sensor when the train is stopped on a slope, using information indicating the relationship between the gradient and acceleration at that position (see, for example, Patent Document 3).Another known method for calibrating an acceleration sensor provided in an on-board device is to correct the measurement value of the acceleration sensor depending on the agreement between the gradient obtained from a server and the gradient determined from the measurement value of the acceleration sensor when the train is traveling on a slope (see, for example, Patent Document 4). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-190232 [Patent Document 2] Japanese Patent Publication No. 2022-190463 [Patent Document 3] Japanese Patent Application Laid-Open No. 2017-147825 [Patent Document 4] Patent Publication No. 2021-99374 Summary of the Invention [Problem to be solved by the invention]

[0005] In the on-board device described in Patent Document 1, if an error occurs in the zero-point correction of the acceleration sensor, a bias will occur in the slope determination based on the road gradient detection results. For example, a situation may occur in which an uphill slope is determined to be a slope even if it is gentle, while a downhill slope is not determined to be a slope if it is gentle, and is not determined to be a slope unless it is steep, thereby reducing the reliability of the slope determination. Furthermore, even when traveling on a route where the number of uphill slopes and the number of downhill slopes should be the same, such as a round-trip route, a discrepancy may occur between the number of uphill slopes and the number of downhill slopes determined. For this reason, the accuracy of the zero-point correction of the acceleration sensor is important.

[0006] To ensure the accuracy of zero-point correction of an acceleration sensor, it is necessary to perform zero-point correction by moving the vehicle to a location with as little gradient as possible and as few unevenness as possible. However, in the case of a typical flat-paved parking lot, the road surface has a water gradient, as well as depressions, unevenness, and roughness that develops over time. Therefore, when measuring the road surface gradient with a level as described in Patent Document 2, the measured value of the road surface gradient varies depending on the measurement position even within the range of a single vehicle's gradient. Therefore, currently, in order to perform zero-point correction by moving the vehicle to a location with as little gradient as possible and as few unevenness as possible, it is necessary to perform this in a dedicated environment such as a vehicle inspection center, which is inefficient.

[0007] On the other hand, the acceleration sensor installed in the vehicle-mounted device is used for other functions such as collision detection in addition to the slope detection function. Therefore, if the acceleration sensor measurement value is corrected or the acceleration sensor zero point is corrected to improve the reliability of the slope detection function, deviations will occur in the reference values ​​for the judgments of the other functions. Here, it is possible to correct the acceleration sensor measurement value for each function, but this would complicate the processing.

[0008] In view of the above circumstances, the present invention aims to provide an on-board device and a program that can accurately determine whether a road is on an uphill or downhill slope without requiring complex processing, even when zero point correction of an acceleration sensor cannot be performed under ideal conditions. [Means for solving the problem]

[0009] The vehicle-mounted device of the present invention is an on-board device equipped with a slope detection function that calculates a gradient value based on the vehicle acceleration measured by an acceleration sensor and determines whether the vehicle is on a slope by comparing it with a slope determination threshold, and is equipped with a counting unit that counts the number of uphill slope determinations and the number of downhill slope determinations for each operation of the vehicle, and a threshold correction unit that corrects the slope determination threshold based on the number of uphill slope determinations and the number of downhill slope determinations counted by the counting unit, and the threshold correction unit calculates the rate of agreement between the outbound trajectory and the return trajectory for each operation of the vehicle, weights the number of uphill slope determinations and the number of downhill slope determinations for each operation of the vehicle counted by the counting unit so that the higher the rate of agreement, the higher the weighting, and corrects the slope determination threshold based on the ratio between the number of uphill slope determinations and the number of downhill slope determinations over multiple operations of the vehicle.

[0010] The program of the present invention is a program for causing an on-board device to execute a slope detection function that calculates a gradient value based on the vehicle acceleration measured by an acceleration sensor and determines a slope by comparing it with a slope determination threshold. The program causes the on-board device to execute a counting procedure that counts the number of uphill slope determinations and the number of downhill slope determinations for each operation of the vehicle, and a threshold correction procedure that corrects the slope determination threshold based on the number of uphill slope determinations and the number of downhill slope determinations counted in the counting procedure. In the threshold correction procedure, the agreement rate between the outbound trajectory and the return trajectory for each operation of the vehicle is calculated, and the number of uphill slope determinations and the number of downhill slope determinations for each operation of the vehicle counted in the counting procedure are weighted so that the higher the agreement rate, the higher the weighting, and the slope determination threshold is corrected based on the ratio between the number of uphill slope determinations and the number of downhill slope determinations over multiple operations of the vehicle. [Effects of the Invention]

[0011] According to the present invention, even when the zero point correction of the acceleration sensor cannot be performed under ideal conditions, it is possible to accurately determine whether the road is on an uphill or downhill slope without requiring complex processing. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a block diagram showing the configuration of an in-vehicle device according to one embodiment of the present invention. [Figure 2] FIG. 2 is a diagram for explaining a method of calculating a gradient value using the acceleration sensor shown in FIG. [Figure 3] FIG. 3 is a flowchart illustrating a method for calculating a gradient value using the acceleration sensor shown in FIG. [Figure 4] FIG. 4 is a flowchart showing the procedure of the automatic calibration function executed by the CPU shown in FIG. [Figure 5] FIG. 5 is a diagram for explaining an embodiment of the automatic calibration function executed by the CPU shown in FIG. [Figure 6] FIG. 6 is a diagram for explaining another embodiment of the automatic calibration function executed by the CPU shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described below in accordance with preferred embodiments. Note that the present invention is not limited to the embodiments shown below and can be modified as appropriate without departing from the spirit of the present invention. In addition, in the embodiments shown below, some components are omitted from illustration and description, but for the details of the omitted technologies, publicly known or well-known technologies are applied as appropriate within the scope of not causing any contradictions with the content described below.

[0014] FIG. 1 is a block diagram showing the configuration of an in-vehicle device 10 according to one embodiment of the present invention. The in-vehicle device 10 shown in this figure is a driving recorder such as a digital tachograph or a drive recorder that also has the functionality of a digital tachograph, and is installed in a vehicle that is the subject of driving management (hereinafter referred to as a managed vehicle). The in-vehicle device 10 has a function (hereinafter referred to as a recording function) for recording driving data, events related to the driving of the managed vehicle, etc. Examples of driving data include time of entry and exit, distance traveled, driving time, and driving speed. Examples of events include speeding, sudden acceleration, sudden deceleration, frequent use of the foot brake 41 on downhill slopes, and engine over-revving.

[0015] Here, when a managed vehicle travels uphill, the engine speed increases even if the driving does not constitute reckless driving. Furthermore, when a vehicle travels downhill, the engine speed increases even if the driver performs appropriate driving by shifting gears and applying the engine brake to prevent frequent use of the foot brake 41. Therefore, the vehicle-mounted device 10 of this embodiment is equipped with a function to detect a slope based on the measurement value of the acceleration sensor 1 (hereinafter referred to as the slope detection function), and suppresses recording of the engine overspeed when an uphill or downhill slope is detected. This allows the vehicle-mounted device 10 of this embodiment to optimize the evaluation of the engine overspeed.

[0016] The slope detection function of the vehicle-mounted device 10 calculates the gradient value S of the road based on the measurement value of the acceleration sensor 1, compares the calculated gradient value S with thresholds S0 and S1, and detects a slope if the calculated gradient value S exceeds the thresholds S0 and S1. Therefore, if there is a deviation in the zero point of the acceleration sensor 1 (hereinafter referred to as an offset error), an error will occur in the calculation result of the gradient value S, and unless some countermeasure is taken, it will be easy to detect either an uphill or downhill slope, and it will be difficult to detect the other (i.e., there will be a bias in the determination of whether the road is an uphill or downhill slope).

[0017] Here, in a case where the entry and exit points of a managed vehicle are within the same area and the trajectories (routes) on the outbound and return journeys are the same, an uphill slope on the outbound journey becomes a downhill slope on the return journey, so the number of uphill slope determinations and the number of downhill slope determinations should be the same. However, in such a case, if there is a bias in the determination of uphill slopes and downhill slopes, there is a possibility that the number of uphill slope determinations and the number of downhill slope determinations will differ. Therefore, in this embodiment, when the entry and exit points of a managed vehicle are within the same area, the vehicle-mounted device 10 corrects the thresholds S0 and S1 (executing the automatic correction function) according to the rate of agreement between the trajectory on the outbound journey and the trajectory on the return journey (hereinafter referred to as the trajectory agreement rate) and the ratio of the number of uphill slope determinations to the number of downhill slope determinations.

[0018] The vehicle-mounted device 10 includes a CPU (Central Processing Unit) 11, a memory 12, an interface (hereinafter, I / F) 13 to which signals output from various sensors and the like are input, and a GPS (Global Positioning System) receiver 14. The vehicle-mounted device 10 also includes a card interface (hereinafter, card I / F) 15, a communication unit 16, and a real-time clock (hereinafter, RTC) 17.

[0019] The CPU 11 controls each part of the vehicle-mounted device 10, and in particular executes the above-mentioned recording function, slope detection function, automatic calibration function, etc. according to a program. The CPU 11 includes a calculation unit 111, a slope determination unit 112, a counting unit 113, a recording unit 114, and a threshold correction unit 115.

[0020] The calculation unit 111 calculates the gradient value S of the road based on the measurement value of the acceleration sensor 1. The slope determination unit 112 performs slope determination by comparing the gradient value S calculated by the calculation unit 111 with threshold values ​​S0 and S1. The counting unit 113 counts the number of times the slope determination unit 112 determines an uphill slope and the number of times it determines a downhill slope during operation of the managed vehicle. Here, the counting unit 113 counts the number of times the slope determination unit 112 determines an uphill slope and the number of times it determines a downhill slope for each operation of the managed vehicle.

[0021] The recording unit 114 records the number of uphill judgments and the number of downhill judgments for each trip of the managed vehicle counted by the counting unit 113 in the memory 12. The recording unit 114 also records the location information (GPS location information, described later) of the managed vehicle in the memory 12 from the time of departure to the time of entry. Here, if both the number of uphill judgments and the number of downhill judgments for each trip of the managed vehicle are equal to or greater than a threshold value (for example, 5 times), the recording unit 114 records the number of uphill judgments and the number of downhill judgments for that trip in the memory 12. On the other hand, if at least one of the number of uphill judgments and the number of downhill judgments for each trip of the managed vehicle is less than the threshold value, the recording unit 114 does not record the number of uphill judgments and the number of downhill judgments for that trip in the memory 12.

[0022] The threshold correction unit 115 weights the number of times an uphill judgment is made and the number of times a downhill judgment is made for each trip of the managed vehicle based on the trajectory match rate for each trip of the managed vehicle. Using the weighted number of times an uphill judgment is made and the number of times a downhill judgment is made, the threshold correction unit 115 corrects the slope judgment threshold based on the ratio X of the number of times an uphill judgment is made to the number of times a downhill judgment is made over multiple trips of the managed vehicle (hereinafter referred to as the uphill / downhill ratio). Details of the processing by the calculation unit 111, slope judgment unit 112, counting unit 113, recording unit 114, and threshold correction unit 115 will be described later.

[0023] The memory 12 is a non-volatile memory that stores programs executed by the CPU 11. The programs executed by the CPU 11 include programs for executing the above-mentioned recording function, slope detection function, and automatic calibration function, as well as a program for executing an alarm function that issues an alarm by audio, video, or the like when an event occurs.

[0024] Memory 12 stores calibration information used in the execution of the automatic calibration function. Here, when a managed vehicle leaves the depot, GPS location information is recorded in memory 12 by recording unit 114, and while the managed vehicle is in operation, the GPS location information is continuously recorded in memory 12 by recording unit 114. Then, when the managed vehicle enters an area specified by the GPS location information recorded in memory 12 at the time of departure, the trajectory match rate for that operation and the number of times an uphill slope was detected and the number of times a downhill slope was detected for that operation are recorded in memory 12 by recording unit 114 as calibration information.

[0025] The operating route for obtaining calibration information is the operating route during normal operation, and it is sufficient that the departure point and the arrival point are within the same area, and it is not necessary for the operating route to be one in which the outbound trajectory and the return trajectory are completely the same.

[0026] The I / F 13 is connected to an acceleration sensor 1, an engine rotation speed sensor 2, a vehicle speed sensor 3, a brake switch 4, a handy numeric keypad (hereinafter referred to as H / T) 5, an in-vehicle camera 6, a switch unit (hereinafter referred to as SWU) 7, a navigation system 8, etc.

[0027] The acceleration sensor 1 detects the acceleration in the vehicle's traveling direction and outputs an acceleration signal to the I / F 13. The engine rotation speed sensor 2 detects the engine rotation speed of the managed vehicle and outputs a rotation speed signal to the I / F 13. The vehicle speed sensor 3 detects the speed of the managed vehicle and outputs a vehicle speed signal to the I / F 13. The brake switch 4 detects the driver's operation of the foot brake 41 and outputs a brake signal to the I / F 13.

[0028] The H / T 5 has various buttons (not shown) arranged thereon, such as an exit button, an ON / OFF button for the automatic calibration function, a button for specifying the outbound / return route, and a button for specifying the occupied / empty vehicle, and outputs operation input signals to the I / F 13. The in-vehicle camera 6 takes images of the area in front of the managed vehicle and outputs image signals to the I / F 13. The SWU 7 also has various buttons (not shown) arranged thereon, such as an exit button, an entry button, an ON / OFF button for the automatic calibration function, a button for specifying the outbound / return route, and a button for specifying the occupied / empty vehicle, and outputs operation input signals to the I / F 13. The navigation system 8 also outputs map information to the I / F 13.

[0029] The GPS receiver 14 is connected to a GPS antenna 141 and receives GPS signals transmitted from GPS satellites (not shown). These GPS signals include GPS position information and GPS time information.

[0030] An external recording medium 151 such as a memory card is detachably attached to the card I / F 15. Operation data and events are recorded in the external recording medium 151 connected to the card I / F 15 by the recording unit 114. The above-mentioned calibration information may also be stored in the external recording medium 151.

[0031] The communication unit 16 communicates with a server and an office PC (both not shown) via a wide area communication network. The RTC 17 keeps track of the current time based on the GPS time information received by the GPS receiver .

[0032] Fig. 2 is a diagram for explaining a method for calculating the gradient value S (%) using the acceleration sensor 1 shown in Fig. 1. As shown in this figure, when a managed vehicle in operation travels on a slope with a gradient value S (%), the gradient value S (%) is calculated using the following formula (1).

number

[0033] The angle θ of the inclined surface satisfies the following formulas (2) to (4).

number

[0034] Fig. 3 is a flowchart for explaining the procedure of the slope detection function executed by CPU 11 shown in Fig. 1. As shown in this flowchart, CPU 11 repeats the processes of steps S21 to S32 while the slope detection function is being executed. While the slope detection function is being executed, calculation unit 111 of CPU 11 calculates gradient value S (%) using formula (1) above every time the management vehicle travels a certain distance (for example, 20 m).

[0035] The slope determination unit 112 of the CPU 11 determines whether the gradient value S (%) calculated by the calculation unit 111 is equal to or greater than a positive threshold value S0 (e.g., +3%) (step S21). If the gradient value S (%) calculated by the calculation unit 111 is equal to or greater than the positive threshold value S0 (YES in step S21), the slope determination unit 112 determines whether the gradient value S (%) calculated by the calculation unit 111 is equal to or greater than the positive threshold value S0 a predetermined number of times (e.g., two times) in succession (step S22).

[0036] If the gradient value S (%) calculated by the calculation unit 111 is equal to or greater than the positive threshold value S0 a predetermined number of times (e.g., twice) in succession (YES in step S22), the slope determination unit 112 turns on the uphill flag (step S23). While the uphill flag is ON, the slope determination unit 112 determines whether the gradient value S (%) calculated by the calculation unit 111 is less than the positive threshold value S0 (step S24). While the gradient value S (%) calculated by the calculation unit 111 is equal to or greater than the positive threshold value S0 (NO in step S24), the slope determination unit 112 keeps the uphill flag ON and returns to step S24. On the other hand, if the gradient value S (%) calculated by the calculation unit 111 is less than the positive threshold value S0 (YES in step S24), the slope determination unit 112 determines whether the gradient value S (%) calculated by the calculation unit 111 has been less than the positive threshold value S0 a predetermined number of times (e.g., two times) in a row (step S25). If the gradient value S (%) calculated by the calculation unit 111 has been less than the positive threshold value S0 a predetermined number of times in a row (YES in step S25), the slope determination unit 112 turns the uphill flag OFF (step S26). On the other hand, if the gradient value S (%) calculated by the calculation unit 111 has been less than the positive threshold value S0 for less than the predetermined number of times (e.g., once) (NO in step S25), the slope determination unit 112 keeps the uphill flag ON and returns to step S24.

[0037] If the slope determination unit 112 makes a negative determination in steps S21 and S22, or if the uphill flag is turned OFF (step S26), the slope determination unit 112 determines whether the gradient value S (%) calculated by the calculation unit 111 is equal to or less than a negative threshold value S1 (e.g., −3%) (step S27). If the gradient value S (%) calculated by the calculation unit 111 is equal to or less than the negative threshold value S1 (YES in step S27), the slope determination unit 112 determines whether the gradient value S (%) calculated by the calculation unit 111 is equal to or less than the negative threshold value S1 a predetermined number of times (e.g., two times) in succession (step S28).

[0038] If the gradient value S (%) calculated by the calculation unit 111 is equal to or less than the negative threshold value S1 for a predetermined number of consecutive times (YES in step S28), the slope determination unit 112 turns on a downhill flag (step S29). While the downhill flag is on, the slope determination unit 112 determines whether the gradient value S (%) calculated by the calculation unit 111 is greater than the negative threshold value S1 (step S30). While the gradient value S (%) calculated by the calculation unit 111 is equal to or less than the negative threshold value S1 (NO in step S30), the slope determination unit 112 keeps the downhill flag on and returns to step S30. On the other hand, if the gradient value S (%) calculated by the calculation unit 111 is greater than the negative threshold value S1 (YES in step S30), the slope determination unit 112 determines whether the gradient value S (%) calculated by the calculation unit 111 is greater than the negative threshold value S1 for a predetermined number of consecutive times (e.g., two times) (step S31). If the gradient value S (%) calculated by the calculation unit 111 is greater than the negative threshold value S1 for a predetermined number of consecutive times (YES in step S31), the slope determination unit 112 turns the downhill flag OFF (step S32). On the other hand, if the gradient value S (%) calculated by the calculation unit 111 remains greater than the negative threshold value S1 for less than a predetermined number of times (for example, once) (NO in step S31), the slope determination unit 112 keeps the downhill flag ON and returns to step S30. If the slope determination unit 112 makes a negative determination in steps S27 and S28 or turns the downhill flag OFF (step S32), it executes the process of step S21.

[0039] Fig. 4 is a flowchart showing the procedure of the automatic calibration function executed by CPU 11 shown in Fig. 1. As shown in this flowchart, after a managed vehicle leaves the warehouse, CPU 11 records the travel path and counts the number of times an uphill slope is determined and the number of times a downhill slope is determined, and after the managed vehicle enters the warehouse, corrects threshold values ​​S0 and S1.

[0040] The recording unit 114 of the CPU 11 determines whether or not the managed vehicle has left the warehouse based on whether or not the leave button on the H / T 5 or SWU 7 has been operated (step S1). If the recording unit 114 determines that the managed vehicle has left the warehouse (YES in step S1), it starts recording the GPS location information in the memory 12 (step S2). Note that the recording unit 114 may also determine whether or not the managed vehicle has left the warehouse based on the GPS location information.

[0041] Next, the counting unit 113 of the CPU 11 starts counting the number of times the slope determination unit 112 has determined that the road is an uphill slope and the number of times the slope determination unit 112 has determined that the road is a downhill slope (step S3). On the other hand, if the managed vehicle has not left the garage (NO in step S1), the counting unit 113 maintains the standby state (step S14).

[0042] The recording unit 114 of the CPU 11 determines whether a managed vehicle has entered the warehouse based on whether the entry button on the H / T 5 or SWU 7 has been operated (step S4). If the entry button has been operated (YES in step S4), the recording unit 114 compares the GPS location information at the time of the exit button operation recorded in the memory 12 with the GPS location information at the time of the entry button operation to determine whether the entry and exit are within the same area (step S5). If the distance between the two points specified by the GPS location information at the time of the exit button operation and the GPS location information at the time of the entry button operation is equal to or less than a predetermined value, the recording unit 114 determines that the exit point and the entry point are within the same area.

[0043] If the departure point and arrival point of the managed vehicle that has completed its operation are within the same area (YES in step S5), the recording unit 114 determines whether the number of uphill judgments and the number of downhill judgments for that operation are both equal to or greater than a threshold value (e.g., 5 times) (step S6). If the number of uphill judgments and the number of downhill judgments for that operation are both equal to or greater than the threshold value (YES in step S6), the recording unit 114 records the number of uphill judgments and the number of downhill judgments for that operation in memory 12 (step S7). On the other hand, if at least one of the number of uphill judgments and the number of downhill judgments for that operation is less than the threshold value (NO in step S6), the recording unit 114 proceeds to step S9 without recording the number of uphill judgments and the number of downhill judgments for that operation in memory 12. Furthermore, if the departure point and arrival point of the managed vehicle that has completed its operation are not within the same area (NO in step S5), the recording unit 114 proceeds to step S9.

[0044] The threshold correction unit 115 calculates the trajectory match rate for the operation, and the recording unit 114 records the calculated trajectory match rate in the memory 12 (step S8). In step S8, the threshold correction unit 115 divides the trajectory of the managed vehicle, identified by the GPS position information recorded in the memory 12 during the operation, into an outbound trajectory and a return trajectory. For example, the threshold correction unit 115 identifies a turnaround point between the outbound and return trajectories based on the GPS position information at the time when a button specifying the outbound / return route is operated, and divides the trajectory of the managed vehicle into the outbound trajectory and the return trajectory with the turnaround point as the boundary. Note that the threshold correction unit 115 may identify the turnaround point between the outbound and return routes based on the GPS position information at the time when a button specifying the occupied / empty vehicle or a button specifying the work input is operated, or may identify the point farthest from the entry / exit point as the turnaround point between the outbound and return routes.

[0045] In step S8, the threshold correction unit 115 determines that the outbound trajectory and the return trajectory match when the distance between them is less than a predetermined value (for example, 5 m), and determines that the outbound trajectory and the return trajectory do not match when the distance between them exceeds the predetermined value. The threshold correction unit 115 calculates a trajectory match rate. The trajectory match rate is the ratio of the round-trip distance to the distance of the section where the outbound trajectory and the return trajectory match.

[0046] The threshold correction unit 115 weights the number of uphill judgments and the number of downhill judgments for each trip of the managed vehicle based on the calculated trajectory match rate, and the recording unit 114 records the weighted number of uphill judgments and the number of downhill judgments in the memory 12 (step S9). The threshold correction unit 115 then calculates an uphill / downhill ratio X, which is the ratio between the total number of uphill judgments and the total number of downhill judgments over multiple trips of the managed vehicle, and the recording unit 114 records the calculated uphill / downhill ratio X in the memory 12 (step S9). The uphill / downhill ratio X is the value obtained by dividing the total number of uphill judgments by the total number of downhill judgments. Note that the uphill / downhill ratio X may also be the value obtained by dividing the average number of uphill judgments by the average number of downhill judgments.

[0047] Fig. 5 is a diagram for explaining one embodiment of the automatic calibration function executed by CPU 11 shown in Fig. 1. As shown in this diagram, for trips (e.g., the first, second, and fourth trips) in which the number of uphill judgments and the number of downhill judgments are both equal to or greater than a threshold value (e.g., five times), the number of uphill judgments and the number of downhill judgments are recorded in memory 12 by recording unit 114. Then, for multiple trips (e.g., three trips) recorded in memory 12, the number of uphill judgments and the number of downhill judgments are weighted based on the trajectory match rate for each trip of the managed vehicle, and the weighted number of uphill judgments and the number of downhill judgments are used to calculate the uphill / downhill ratio X for the multiple trips of the managed vehicle.

[0048] When the calculated up / down ratio X exceeds the threshold value Y or is less than the threshold value Z (= 1 / Y) (X > Y or X < Z), automatic calibration (correction of threshold values S0 and S1) is executed. Here, the threshold value Y satisfies 1.0 < Y ≤ 2.0, for example, 1.4 ≤ Y ≤ 2.0. Also, the threshold value Z satisfies 0.5 ≤ Z < 1.0, for example, 0.5 (= 1 / 2.0) ≤ Z ≤ 0.7 (≈ 1 / 1.4). On the other hand, when the up / down ratio X is between the threshold value Z and the threshold value Y (Z ≤ X ≤ Y), the threshold values S0 and S1 are not corrected.

[0049] In the embodiment shown in FIG. 5, for a run where the trajectory matching rate is equal to or higher than a predetermined value (for example, 80%), the run is regarded as having been executed twice, and the total value of the number of uphill slope determination times and the total value of the number of downhill slope determination times in multiple runs of the management vehicle are calculated.

[0050] In the example shown in FIG. 5, when the number of uphill slope determination times and the number of downhill slope determination times are not weighted, the total value of the number of uphill slope determination times is 30, the total value of the number of downhill slope determination times is 20, and the ratio of the number of uphill slope determination times to the number of downhill slope determination times is 1.50. On the other hand, when the number of uphill slope determination times and the number of downhill slope determination times are weighted, the total value of the number of uphill slope determination times is 30, the total value of the number of downhill slope determination times is 21, and the up / down ratio X is 1.43. When the threshold value Y is 1.40, in either case, correction of the threshold values S0 and S1 is required.

[0051] When the number of uphill slope determination times and the number of downhill slope determination times in two runs of the first run and the second run are weighted and the weighted values are used to calculate the up / down ratio X, the total value of the number of uphill slope determination times is 30, the total value of the number of downhill slope determination times is 23, and the up / down ratio X is 1.30. In this case, since the up / down ratio X is between the threshold value Z and the threshold value Y, correction of the threshold values S0 and S1 is not required.

[0052] FIG. 6 is a diagram illustrating another example of the automatic calibration function executed by the CPU 11 shown in FIG. 1. In the example shown in this figure, for a journey in which the trajectory matching rate is equal to or greater than a first predetermined value P1% (e.g., 80%), the number of uphill judgments and the number of downhill judgments are multiplied by α (1<α<2, e.g., 1.5 times). For a journey in which the trajectory matching rate is less than the first predetermined value P2% (e.g., less than 30% and less than 80%), the number of uphill judgments and the number of downhill judgments are multiplied by β (0<β<α, e.g., 1.0 times). For a journey in which the trajectory matching rate is less than a third predetermined value P3% (e.g., less than the second predetermined value P2, e.g., less than 30%), the number of uphill judgments and the number of downhill judgments are multiplied by γ (0<γ<β, e.g., 0.5 times).

[0053] In the example shown in FIG. 6, if the number of uphill judgments and the number of downhill judgments are not weighted, the total number of uphill judgments is 30, the total number of downhill judgments is 20, and the ratio between the number of uphill judgments and the number of downhill judgments is 1.50. If threshold Y is 1.40, correction of thresholds S0 and S1 is necessary. In contrast, if the number of uphill judgments and the number of downhill judgments are weighted, the total number of uphill judgments is 30, the total number of downhill judgments is 21.5, and the uphill / downhill ratio X is 1.40. If threshold Y is 1.40, the uphill / downhill ratio X does not exceed threshold Y, so correction of thresholds S0 and S1 is not necessary.

[0054] 4, the threshold correction unit 115 determines whether the uphill / downhill ratio X for multiple (e.g., three) trips of the managed vehicle exceeds the threshold Y (step S10). If the uphill / downhill ratio X exceeds the threshold Y (YES in step S10), the threshold correction unit 115 corrects the threshold S0 for determining an uphill slope and the threshold S1 for determining a downhill slope so that the uphill / downhill ratio X approaches 1 (the number of times an uphill slope is determined and the number of times a downhill slope is determined become equal) (step S11). For example, the threshold correction unit 115 increases the threshold S0 for determining an uphill slope by an amount corresponding to the uphill / downhill ratio X (e.g., +0.5%), and increases the threshold S1 for determining a downhill slope by an amount corresponding to the uphill / downhill ratio X (e.g., +0.5%). In other words, the threshold correction unit 115 increases the absolute value of the threshold S0 for determining an uphill slope by an amount corresponding to the uphill / downhill ratio X (for example, 0.5%), and decreases the absolute value of the threshold S1 for determining a downhill slope by an amount corresponding to the uphill / downhill ratio X (for example, 0.5%).

[0055] If the uphill / downhill ratio X is equal to or less than the threshold Y (NO in step S10), or after executing step S11, the threshold corrector 115 determines whether the uphill / downhill ratio X is less than the threshold Z (step S12). If the uphill / downhill ratio X is less than the threshold Z (YES in step S12), the threshold corrector 115 corrects the threshold S0 for determining an uphill slope and the threshold S1 for determining a downhill slope so that the uphill / downhill ratio X approaches 1 (step S13). For example, the threshold corrector 115 reduces the threshold S0 for determining an uphill slope by an amount corresponding to the uphill / downhill ratio X (for example, -0.5%), and reduces the threshold S1 for determining a downhill slope by an amount corresponding to the uphill / downhill ratio X (for example, -0.5%). In other words, the threshold correction unit 115 decreases the absolute value of the threshold S0 for determining an uphill slope by an amount corresponding to the uphill / downhill ratio X (for example, 0.5%), and increases the absolute value of the threshold S1 for determining a downhill slope by an amount corresponding to the uphill / downhill ratio X (for example, 0.5%).

[0056] After the CPU 11 corrects the threshold value S0 for determining an uphill slope and the threshold value S1 for determining a downhill slope in step S13, or after a negative judgment is made in steps S1 and S12, the CPU 11 transitions to a standby state (step S14).

[0057] As explained above, in the vehicle-mounted device 10 of this embodiment, the counting unit 113 of the CPU 11 counts the number of uphill and downhill judgments for each trip of the managed vehicle, and the threshold correction unit 115 of the CPU 11 corrects the thresholds S0 and S1 based on the number of uphill and downhill judgments counted by the counting unit 113. This makes it possible to correct the thresholds S0 and S1 for determining slopes, and to make even judgments about uphill and downhill slopes, even in situations where zero point correction of the acceleration sensor 1 cannot be performed in an ideal environment where zero point correction of the acceleration sensor 1 is performed, such as a vehicle inspection center.

[0058] Here, the threshold correction unit 115 calculates the trajectory match rate, which is the rate of match between the outbound trajectory and the return trajectory, for each trip of the managed vehicle, and weights the number of uphill judgments and the number of downhill judgments for each trip of the managed vehicle counted by the counting unit 113 so that the higher the trajectory match rate, the greater the weighting.The threshold correction unit 115 then corrects the thresholds S0 and S1 based on the ratio between the number of uphill judgments and the number of downhill judgments over multiple trips of the managed vehicle.

[0059] This allows the number of times an uphill slope is determined and the number of times a downhill slope is determined counted by the counting unit 113 during the trip to be included in the information for correcting the thresholds S0 and S1, even when the managed vehicle travels on a route with different trajectories on the outbound and return journeys. This also ensures the reliability of the information for correcting the thresholds S0 and S1. This ensures ample opportunities to obtain information for correcting the thresholds S0 and S1 and correct the thresholds S0 and S1, and also enables the correction of the thresholds S0 and S1 to be performed with high accuracy.

[0060] Furthermore, although the acceleration sensor 1 is used for other functions such as collision detection in addition to the slope detection function, the measurement values ​​of the acceleration sensor 1 are not corrected, which prevents deviations from occurring in the reference values ​​for the judgments of other functions. In addition, complex processing such as correcting the acceleration sensor 1 for each function can be avoided.

[0061] Furthermore, while the offset error of the acceleration sensor 1 may occur due to the influence of the environment such as temperature and the vehicle state such as vibration, the threshold values ​​S0 and S1 are corrected in a state that takes into account the influence of the environment, vehicle state, etc. This ensures the accuracy of slope determination regardless of the influence of the environment during driving, vehicle state, etc.

[0062] Furthermore, the accuracy of slope detection can be ensured by correcting the thresholds S0 and S1 for the offset error of the acceleration sensor 1, thereby expanding the allowable range of the offset error of the acceleration sensor 1. Therefore, the accuracy of slope detection can be ensured without requiring a high-precision, high-cost acceleration sensor 1 with little offset error, or without adding another sensor for calibrating the acceleration sensor 1.

[0063] Furthermore, by being able to properly determine whether the road is an uphill or downhill slope, it is possible to properly determine whether the engine is over-revving.

[0064] Furthermore, in the vehicle-mounted device 10 of this embodiment, the recording unit 114 records the number of uphill and downhill determinations in the memory 12 for each trip, excluding trips in which at least one of the number of uphill and downhill determinations is below the threshold. Therefore, the threshold correction unit 115 corrects the thresholds S0 and S1 based on the trajectory match rate and the uphill / downhill ratio X for multiple trips, excluding trips in which at least one of the number of uphill and downhill determinations is below the threshold. In other words, for trips in which the number of uphill and downhill determinations is relatively low, the calibration information acquired for that trip is removed as noise. This improves the reliability of slope detection.

[0065] Also, in the vehicle-mounted device 10 of the present embodiment, when the up / down ratio X in multiple runs satisfies the condition of X > Y or X < Z (where 1.0 < Y ≤ 2.0, 0.5 ≤ Z < 1.0), the threshold values S0 and S1 are corrected. Thereby, the correction of the threshold values S0 and S1 can be executed only when the deterioration of the accuracy of the slope determination due to the offset error of the acceleration sensor 1 exceeds the allowable range, and an excessive processing load can be avoided.

[0066] Also, in the vehicle-mounted device 10 of the present embodiment, when the up / down ratio X exceeds the threshold value Y, the absolute value of the threshold value S0 for determining an uphill is increased, and the absolute value of the threshold value S1 for determining a downhill is decreased. On the other hand, when the up / down ratio X is less than the threshold value Z, the threshold value correction unit 115 decreases the absolute value of the threshold value S0 for determining an uphill and increases the absolute value of the threshold value S1 for determining a downhill. Thereby, the ratio of the number of uphill determinations to the number of downhill determinations can be made closer to 1.

[0067] As described above, the present invention has been described based on the above-described embodiments. However, the present invention is not limited to the above-described embodiments, and modifications may be made without departing from the gist of the present invention, or known and well-known techniques may be appropriately combined.

[0068] For example, in the above-described embodiment, the threshold value correction unit 115 corrects the threshold values S0 and S1 when the up / down ratio X satisfies the condition of X > Y or X < Z. However, the threshold value correction unit 115 may correct the threshold values S0 and S1 according to the up / down ratio X regardless of whether the up / down ratio X satisfies the condition of X > Y or X < Z.

[0069] Furthermore, in the above-described embodiment, the acceleration sensor 1 is provided in the vehicle-mounted device 10. However, the acceleration sensor 1 only needs to be vehicle-mounted and may be provided in a vehicle-mounted device different from the vehicle-mounted device 10, or may be provided in a vehicle.

Explanation of Reference Numerals

[0070] 1: Acceleration sensor 10: Onboard equipment 113:Counting section 115: Threshold correction unit S: Gradient value S0, S1: Threshold (slope determination threshold) X: Uphill / Downhill Ratio (the ratio of the number of times an uphill slope is detected to the number of times a downhill slope is detected)

Claims

1. An in-vehicle device having a slope detection function that calculates a gradient value based on the acceleration of a vehicle measured by an acceleration sensor and determines whether the vehicle is on a slope by comparing the gradient value with a slope determination threshold, a counting unit that counts the number of times an uphill slope is determined and the number of times a downhill slope is determined for each operation of the vehicle; a threshold correction unit that corrects the slope determination threshold based on the number of times the uphill slope has been determined and the number of times the downhill slope has been determined counted by the counting unit; Equipped with The threshold correction unit calculating a coincidence rate between the outbound trajectory and the inbound trajectory for each trip of the vehicle; weighting the number of times the uphill slope has been determined and the number of times the downhill slope has been determined for each operation of the vehicle counted by the counting unit so that the higher the coincidence rate, the greater the weighting; The slope determination threshold is corrected based on the ratio of the number of times the vehicle has been determined to be an uphill slope to the number of times the vehicle has been determined to be a downhill slope during multiple trips of the vehicle. Onboard equipment.

2. The vehicle-mounted device according to claim 1, wherein the threshold correction unit corrects the slope determination threshold in accordance with the ratio of the number of times the vehicle has determined that it has an uphill slope to the number of times the vehicle has determined that it has a downhill slope during multiple trips of the vehicle, except when at least one of the number of times the vehicle has determined that it has an uphill slope and the number of times the vehicle has determined that it has a downhill slope is less than the threshold.

3. 3. The vehicle-mounted device according to claim 1, wherein the threshold correction unit corrects the slope determination threshold when a ratio between the number of times the vehicle has determined that it is an uphill slope and the number of times the vehicle has determined that it is a downhill slope satisfies a predetermined condition defined by the following formula: X>Y or X<Z X is the ratio of the number of times an uphill slope is determined to the number of times a downhill slope is determined during multiple trips of the vehicle. Y is in the range of 1.0<Y≦2.

0. Z is in the range of 0.5≦Z<1.

0.

4. The threshold correction unit If X>Y, the absolute value of the slope determination threshold for determining an upslope is increased, and the absolute value of the slope determination threshold for determining a downslope is decreased; 4. The vehicle-mounted device according to claim 3, wherein, when X<Z, the absolute value of the slope determination threshold for determining an uphill slope is decreased, and the absolute value of the slope determination threshold for determining a downhill slope is increased.

5. A program for causing an in-vehicle device to execute a slope detection function that calculates a gradient value based on the acceleration of a vehicle measured by an acceleration sensor and determines whether the vehicle is on a slope by comparing the gradient value with a slope determination threshold, a counting step of counting the number of times an uphill slope is determined and the number of times a downhill slope is determined for each operation of the vehicle; a threshold value correction step of correcting the slope determination threshold value based on the number of times the vehicle has been determined to be an uphill slope and the number of times the vehicle has been determined to be a downhill slope counted in the counting step; The vehicle-mounted device executes the above. In the threshold correction step, calculating a coincidence rate between the outbound trajectory and the inbound trajectory for each trip of the vehicle; weighting the number of times the uphill slope determination is made and the number of times the downhill slope determination is made for each trip of the vehicle counted in the counting step so that the higher the coincidence rate, the higher the weighting; The slope determination threshold is corrected based on the ratio of the number of times the vehicle has been determined to be an uphill slope to the number of times the vehicle has been determined to be a downhill slope during multiple trips of the vehicle. program.

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