JP2011058967A - Correction device for acceleration sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a correction device capable of correcting accurately an output value of an acceleration sensor loaded on a vehicle. <P>SOLUTION: This correction device (navigation device) 200 for an acceleration sensor connected to an acceleration sensor 221 for measuring a first acceleration applied to the vehicle 20, and to a position detection means 220 or a speed sensor installed on the vehicle, includes a control means 210 and a storage means 222. The control means 210 calculates a second acceleration based on output from the position detection means 220 or the speed sensor, and stores a difference determined from the first acceleration and the second acceleration, or a parameter such as an inclination of the vehicle, successively in the storage means 222. When the accumulated mileage of the vehicle reaches a prescribed value, the control means 210 calculates the mean value of stored parameters, and corrects the acceleration sensor 221 by using the mean value as a correction value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a correction device for correcting an error caused by a deviation in the mounting angle of an acceleration sensor installed in a vehicle or an output error caused by secular change, and in particular, an average of road surface angles obtained from an acceleration sensor. The present invention relates to a method for calculating a correction value based on a value.

  In general, an acceleration sensor attached to a vehicle outputs acceleration when the vehicle accelerates or decelerates. Based on the output of the acceleration sensor, it can detect gravity, vibration or movement, and impact applied to the vehicle. it can.

  When the vehicle travels on a hill or the like, the vehicle tilts. At that time, the direction of the gravitational acceleration applied to the acceleration sensor changes, so that the tilt of the vehicle can be detected. Moreover, it is possible to operate various functions provided in the vehicle, such as an airbag, by detecting a specific vibration or impact applied to the vehicle.

  When the acceleration sensor is attached to a predetermined part of the automobile, the attachment state of the acceleration sensor may slightly change over time, or the characteristics of the acceleration sensor itself may change. For this reason, the output value of the acceleration sensor shifts with time.

  For this purpose, there is conventionally known an apparatus that detects an output value of an acceleration sensor when the vehicle is stopped and determines a correction amount so that the output value becomes zero. This is because when the vehicle is in a stopped state, the vehicle is not subjected to front / rear / right / left acceleration, so that the acceleration sensor mounted on the vehicle is naturally not subjected to acceleration and the output value becomes zero. It is based on the principle that it should be.

  However, even when the vehicle is stopped, the road surface is not necessarily horizontal, and may be inclined in the front-rear direction or may be inclined left and right. In such a case, the output value of the acceleration sensor is naturally influenced by such inclination, and the acceleration in the front-rear or left-right direction is reflected. The output value at this time is inappropriate for use as a correction value for the acceleration sensor.

  Therefore, the following Patent Document 1 (Japanese Patent Laid-Open No. 7-301641) judges that the vehicle is stopped on a flat ground when the output value of the acceleration sensor when the vehicle is stopped is equal to or less than a predetermined value. Disclosed is a “vehicle acceleration sensor correction device” that performs zero point correction of an acceleration sensor and, when an output value exceeding a predetermined value is output, assumes that the vehicle is stopped on an inclined road and does not perform zero point correction. is doing.

  In the invention of the “vehicle acceleration sensor correction device”, when the output value of the acceleration sensor is measured, the inclination angle in the output value is calculated assuming that the output value is caused by the inclination of the stop road surface. Then, it is determined whether the inclination angle is larger or smaller than a predetermined value. When it is determined that the inclination angle is small, it is determined that the vehicle is stopped on a substantially flat road surface, and the above-described output value is stored as a correction amount. On the other hand, when the value calculated from the output value is larger than the predetermined value, the output value is not stored as a correction value.

JP 7-301641 A

  In the invention of the “vehicle quantity acceleration sensor correcting device” disclosed in Patent Document 1, when the output value is equal to or less than a predetermined value, it is always considered that the vehicle is stopped on a flat ground. Actually, the output value should be different between when the road surface is horizontal and when it is slightly inclined. However, the output values of both are regarded as being stopped on a horizontal road surface, and are adopted as correction values for the acceleration sensor. For this reason, the correction device of Patent Document 1 cannot obtain an accurate correction value.

  Accordingly, an object of the present invention is to provide a correction device that accurately corrects an output value of an acceleration sensor mounted on a vehicle.

  A further object of the present invention is mounted on a vehicle regardless of whether the vehicle is located on a horizontal road surface or an inclined road surface, and whether the vehicle is running or stopped. An object of the present invention is to provide a correction device that obtains an accurate correction value of an acceleration sensor.

  In order to achieve the above object, an acceleration sensor correction apparatus according to claim 1 of the present application includes an acceleration sensor for measuring a first acceleration applied to a vehicle, and a position detection means or a speed sensor installed in the vehicle. An acceleration sensor correction apparatus connected to the acceleration sensor correction apparatus, the acceleration sensor correction apparatus including a control unit and a storage unit, wherein the control unit is based on an output from the position detection unit or the speed sensor. A second acceleration is calculated, parameters obtained from the first acceleration and the second acceleration are sequentially stored in the storage means, and when the cumulative travel history of the vehicle reaches a predetermined value, the storage is performed. A correction value is calculated based on the set parameter, and the acceleration sensor is corrected using the correction value.

  The invention according to claim 2 of the present application is the acceleration sensor correcting device according to claim 1, wherein the parameter is a difference between the first acceleration and the second acceleration.

  The invention according to claim 3 of the present application is the acceleration sensor correction device according to claim 2, wherein the control means calculates an average value of the parameters as the correction value.

  According to a fourth aspect of the present invention, in the acceleration sensor correction device according to the first aspect, the parameter is an inclination of the vehicle obtained from a difference between the first acceleration and the second acceleration. It is characterized by being.

  According to a fifth aspect of the present invention, in the acceleration sensor correction device according to the fourth aspect, the control means obtains an arc sine from a difference between the first acceleration and the second acceleration. The inclination of the vehicle is calculated.

  In the invention according to claim 6 of the present application, in the acceleration sensor correction device according to claim 4 or 5, the control means calculates an average value of the calculated vehicle inclination, and the calculated vehicle The correction value is calculated by obtaining a sine from the average value of the slopes of the above.

  Further, the invention according to claim 7 of the present application is the acceleration sensor correction device according to any one of claims 1 to 6, wherein the control means is based on an output from the position detection means or the speed sensor. The parameter is calculated from the first acceleration and the second acceleration when it is detected that the speed of the vehicle is equal to or higher than a predetermined speed.

  The invention according to claim 8 of the present application is the acceleration sensor correction device according to any one of claims 1 to 7, wherein the cumulative travel history includes a cumulative travel distance, a cumulative travel time, and a cumulative parameter number. Any one or more are included.

  With the above configuration, the present invention has the following excellent effects. That is, according to the invention of the correction device for acceleration sensor according to claim 1, the acceleration sensor for measuring the first acceleration applied to the vehicle, and the acceleration sensor connected to the position detecting means or the speed sensor installed in the vehicle. The acceleration sensor correction apparatus includes a control unit and a storage unit, and the control unit calculates a second acceleration based on an output from the position detection unit or the speed sensor. Then, parameters obtained from the first acceleration and the second acceleration are sequentially stored in the storage means, and when the cumulative travel history of the vehicle reaches a predetermined value, correction is performed based on the stored parameters. A value is calculated, and the acceleration sensor is corrected using the correction value. As a result, the correction value of the acceleration sensor mounted on the vehicle is obtained regardless of whether the vehicle is positioned on a horizontal road surface or an inclined road surface, and whether the vehicle is running or stopped. It becomes possible.

  According to a second aspect of the present invention, in the acceleration sensor correction device according to the first aspect, the parameter is a difference between the first acceleration and the second acceleration. As a result, it is possible to easily calculate a parameter as a basis for obtaining the correction value.

  According to a third aspect of the invention, in the acceleration sensor correction apparatus according to the second aspect, the control means calculates an average value of the parameters as the correction value. Thus, a correction value can be obtained, and the acceleration sensor can be corrected by using this correction value.

  According to the invention of claim 4, in the acceleration sensor correction device according to claim 1, the parameter is an inclination of the vehicle obtained from a difference between the first acceleration and the second acceleration. is there. As a result, a parameter as a basis for obtaining the correction value can be obtained as an angle value.

  According to the invention of claim 5, in the acceleration sensor correction apparatus according to claim 4, the control means obtains an arc sine from the difference between the first acceleration and the second acceleration. The inclination of the vehicle is calculated. Thereby, the inclination of the vehicle can be accurately obtained.

  According to the invention of claim 6, in the acceleration sensor correction apparatus according to claim 4 or 5, the control means calculates an average value of the calculated vehicle inclination, and the calculated vehicle The correction value is calculated by obtaining a sine from the average value of the slopes. Thus, a correction value can be obtained, and the acceleration sensor can be corrected by using this correction value.

  According to a seventh aspect of the present invention, in the acceleration sensor correction device according to any one of the first to sixth aspects, the control unit is configured to output the vehicle based on an output from the position detection unit or the speed sensor. The parameter is calculated from the first acceleration and the second acceleration when it is detected that the speed is equal to or higher than a predetermined speed. This is because if the vehicle speed is low, the output error of the position detection means, the acceleration sensor, etc. becomes large, so the parameter is calculated by calculating the parameter from the first acceleration and the second acceleration when the vehicle speed exceeds the predetermined speed. Parameters can be obtained.

  According to an eighth aspect of the present invention, in the acceleration sensor correction device according to any one of the first to seventh aspects, the cumulative travel history is any one of a cumulative travel distance, a cumulative travel time, and a cumulative parameter number. Contains one or more. Thereby, when the accumulated travel history such as the accumulated travel distance reaches a predetermined value, the acceleration sensor can be corrected. This is an application of the fact that the total and average values of the stored parameters converge to zero when the cumulative travel history such as the cumulative travel distance becomes large.

FIG. 1 is an explanatory diagram of the correction principle of the acceleration sensor. FIG. 2 is an internal block diagram of the navigation apparatus according to the present embodiment. FIG. 3 is an operation flowchart showing correction value determination of the acceleration sensor in the navigation device 200.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best mode for carrying out the present invention will be described in detail below with reference to the drawings together with embodiments. However, the embodiment described below illustrates a navigation device as an acceleration sensor correction device for embodying the technical idea of the present invention, and the present invention is specified to this navigation device. The present invention is not intended and can be equally applied to other acceleration sensor correction devices without departing from the technical idea shown in the claims.

  First, the principle of the acceleration sensor correction apparatus of the present invention will be described with reference to FIG. FIG. 1 is an explanatory diagram of the correction principle of the acceleration sensor. FIG. 1A shows a state where a vehicle 20 equipped with an acceleration sensor 30 is stopped on a horizontal road surface 10A. Here, for the sake of simplicity, it is assumed that the acceleration sensor 30 outputs an acceleration only in the traveling direction of the vehicle 20, and a direction component perpendicular to the traveling direction of the vehicle 20 is not output. Since the vehicle 20 is stopped, the acceleration sensor 30 does not detect any acceleration. The gravitational acceleration g is ignored because it is a direction component perpendicular to the traveling direction of the vehicle 20.

FIG. 1B shows a state where the same vehicle 20 is traveling while accelerating at an acceleration a ₀ on a horizontal road surface 10A. In this case the acceleration sensor 30, detects the acceleration of a _0. As in FIG. 1A, the gravitational acceleration g is ignored because it is a direction component perpendicular to the traveling direction of the vehicle 20.

Reference is now made to FIG. 1C. FIG. 1C shows a state where the same vehicle 20 is stopped on an inclined road 10B inclined at θ degrees with respect to the horizontal direction. At this time, since the vehicle 20 is tilted along the ramp 10B, the acceleration sensor 30 mounted on the vehicle 20 is also tilted by θ degrees from the horizontal direction. Then, the traveling direction component of the vehicle 20 of the gravitational acceleration g ignored on the horizontal road surface 10A is detected by the acceleration sensor 30. In other words, the gravitational acceleration g applied to the acceleration sensor 30 can be decomposed into g · sin θ that is a traveling direction component of the vehicle 20 and g · cos θ that is a vertical direction component with respect to the traveling direction of the vehicle 20. Among them, since the vertical component with respect to the traveling direction of the vehicle 20 is not output and is ignored, the acceleration a ₀ detected by the acceleration sensor 30 corresponds to g · sin θ.

Still referring to FIG. 1D. FIG. 1D shows a state where the same vehicle 20 is traveling while accelerating in the X direction at an acceleration a on an inclined road 10B inclined at θ degrees with respect to the horizontal direction. Here, the X direction means a direction parallel to the ramp 10B. The acceleration a at this time is in the road surface direction of the inclined road 10B, that is, in the X direction, and this direction coincides with the traveling direction of the vehicle 20. The acceleration a ₀ detected by the acceleration sensor 30 at this time is the sum of the traveling acceleration a of the automobile 20 and the road surface direction component of the gravitational acceleration applied to the acceleration sensor 30, and is expressed by the following equation (1). Is done.

a ₀ = a + g · sin θ (1)
The following relationship is derived from Equation (1).

θ = sin ⁻¹ ((a ₀ −a) / g) (2)
According to equation (2), it can be seen that the inclination angle θ of the ramp 10B is obtained from the output of the acceleration sensor 30 and the running acceleration of the automobile. The running acceleration of the automobile is obtained from the equation (3).

a = dV / dt = d ² X / dt ² (3)
Here, V is the traveling speed of the automobile, and X is the displacement of the automobile. Accordingly, the traveling acceleration can be calculated by differentiating the output value of the speed sensor mounted on the automobile 10. Alternatively, the travel acceleration can be obtained by receiving a signal from a GPS satellite in a GPS receiver mounted on the automobile 10 and second-order differentiation of the displacement of the current position calculated based on the measurement result.

  Here, when the road surface angle is periodically accumulated along with the traveling of the automobile and the sum is taken, it should converge to 0 as the traveling distance of the automobile becomes longer. However, in practice, the road surface angle may not be converged to 0 degrees due to an error caused by a shift in the mounting angle of the acceleration sensor 30 or an output error caused by the secular change of the acceleration sensor 30. The deviation from 0 degree of the road surface angle that occurs when the travel distance becomes longer can be used as the correction value of the acceleration sensor 30, and the output value of the acceleration sensor measured after that can be corrected appropriately. It becomes.

An embodiment in which the principle of acceleration sensor correction described above is applied to the navigation apparatus 200 will be described below. In the following description, as described with reference to FIG. 1, the acceleration applied to the automobile, that is, the acceleration detected by the acceleration sensor is defined as a _0, and the traveling acceleration obtained from the displacement of the position of the automobile is defined as a. . FIG. 2 is an internal block diagram of the navigation device 200 according to the present embodiment. The navigation device 200 is specifically a car navigation device mounted on an automobile, and includes a control unit 210, a GPS receiver 220, an acceleration sensor 221, a storage unit 222, a map storage unit 223, a display unit 224, and an input unit 225. The audio output means 226 is provided.

  The control means 210 is for controlling and supervising the operation of each part of the navigation device 200. The control means 210 is composed of a processor including a CPU, a RAM, a ROM, etc., and the operation of each part is executed by executing a control program stored in the ROM. Control and control. The control unit 210 further includes a speed / distance calculation determination unit 211, an acceleration calculation unit 212, a road surface angle calculation unit 213, a route search unit 214, and a route guidance unit 215 as functional blocks.

  The GPS receiver 220 receives a signal from a GPS satellite and calculates a current position. The GPS receiver 220 detects the current position at a predetermined time interval, for example, one second interval. The calculated current position is temporarily stored in the storage unit 222 described later.

The acceleration sensor 221 detects the acceleration a ₀ applied to the automobile to which the navigation device 200 is attached. The acceleration sensor 221 is a triaxial acceleration sensor, for example, and can detect not only the acceleration in the traveling direction of the vehicle but also the vertical component in the traveling direction. By detecting the acceleration applied to the automobile, the current position of the automobile can be determined by using the detected acceleration even when there is an obstacle such as a tunnel or a building street and a signal from a GPS satellite cannot be received. It is possible to detect. The acceleration detected by the acceleration sensor 221 corresponds to the “first acceleration” in the claims.

  The storage means 222 is composed of a RAM, a ROM, a hard disk drive, or the like, and stores a current position calculated by the GPS receiver 220, a speed calculated from a displacement of the current position described later, a traveling acceleration, a road surface angle, and the like. is there.

  The map storage means 223 stores road data including road node data obtained by converting nodes such as intersections and branch points of each road into nodes, and road link data obtained by converting routes connecting the nodes as links. ing. Road node data includes node numbers, position coordinates, number of connected links, intersection names, etc., road link data includes node numbers as starting and ending points, road types, link costs, link attributes such as bridges and tunnels, etc. Is included. The map storage means 223 further stores background data such as coastlines, lakes, river shapes, administrative boundaries, and facilities.

  The display unit 224 is configured by a liquid crystal display panel or the like, and plays a role as a man-machine interface for displaying a map image and an optimum route image so that the user can visually recognize the map image and the optimum route image.

  The input unit 225 includes keys, operation buttons, switches, and the like, and is used by the user to input a departure place, a destination, and other conditions while visually recognizing a selection menu displayed on the display unit 224. The display means 224 and the input means 225 may be constituted by a touch panel type liquid crystal display unit.

  The voice output means 226 has a speaker, and when the vehicle reaches a predetermined point before a guide point such as an intersection on the guidance route, the voice output means 226 outputs a voice of the traveling direction of the vehicle along with the name of the intersection and the distance to the intersection. is there. The voice output means 226 is also used when outputting operation guidance for the navigation device 200 and various warnings / notifications by voice.

The speed / distance calculation determination unit 211 of the control unit 210 calculates the speed based on the current position calculated by the GPS receiver 220 and stored in the storage unit 222. The calculation of the current position by the GPS receiver 220 is performed, for example, every second, and the speed / distance calculation determination unit 211
Each time the current position is calculated, the speed from the current position calculated last time to the current position calculated this time is calculated, and the speed can be obtained by differentiating this displacement with time. The speed / distance calculation determination unit 211 calculates the accumulated travel distance by storing the calculated displacement in the storage unit 222. Although the method for calculating the speed based on the current position calculated by the GPS receiver 220 has been described here, a speed sensor is provided in the navigation device 200 in place of the GPS receiver 220, and the output value of the speed sensor is set. It may be used. The cumulative travel distance can also be calculated by integrating the calculated speed and storing it in the storage means 222.

  The acceleration calculating means 212 obtains the running acceleration a of the automobile by further time-differentiating the speed value calculated by the speed / distance calculation determining means 211 described above. The calculated traveling acceleration is stored in the storage unit 222. Here, the traveling acceleration is an acceleration when only the moving direction of the automobile is taken into consideration, and corresponds to a “second acceleration” in the claims.

  The road surface angle calculation unit 213 obtains the road surface angle from the above equation (2) based on the travel acceleration calculated by the speed / distance calculation determination unit 211 and the acceleration value output by the acceleration sensor 221. The calculated road surface angle is stored in the storage unit 222.

  The route search means 214 searches the road data stored in the map storage means 223 for a route from the identified starting point or current position to the destination point by operating the input means 225, and the link cost. Is determined as the optimum route, and road data related to the optimum route is stored in the storage unit 222.

  The route guidance means 215 creates a route guidance screen based on the road data related to the optimum route stored in the storage means 222 and displays it on the display means 224, or in accordance with the road data relating to the optimum route, by the GPS receiver 220. The driving of the automobile is monitored while receiving the position, and guidance guidance or the like is notified using the voice output means 226 at an appropriate position.

  Next, with reference to FIG. 3, the flow of operation for determining the correction value of the acceleration sensor in the navigation device 200 described above will be described. FIG. 3 is an operation flowchart showing determination of the correction value of the acceleration sensor in the navigation device 200.

In step S <b> 301 of FIG. 3, the acceleration sensor 221 mounted on the vehicle measures the acceleration a _{0 applied} to the vehicle and stores the value in the storage unit 222. The acceleration when the automobile is stopped may be measured and stored in advance, and the stored acceleration may be subtracted from the acceleration a ₀ as a gravitational acceleration component depending on the mounting angle of the navigation device 200 or the acceleration sensor 221. .

  In subsequent step S <b> 302, signals from GPS satellites are received by the GPS receiver 220, the current position is calculated based on those signals, and temporarily stored in the storage unit 222. This current position is calculated every second, for example. Each time the current position is calculated, the speed / distance calculation determination unit 211 calculates the displacement from the current position calculated last time, calculates the speed of the automobile in the subsequent step S303, and stores it in the storage unit 222. Further, the displacement for each calculation is accumulated and stored in the storage means 222, whereby the accumulated travel distance can be obtained.

  In step S304, the speed / distance calculation determination unit 211 determines whether or not the speed of the automobile is equal to or higher than a predetermined speed, for example, 20 km / h or more (5.56 m / s or more). If it is less than 20 km / h, the process returns to step S301 and the above process is repeated. If it is determined that the vehicle speed is 20 km / h or higher, the process proceeds to the subsequent step S305. The reason why the speed of the automobile is 20 km / h or more is that when the speed is as low as 20 km / h or less, the moving distance becomes short and the accuracy of the current position detected by the GPS receiver 220 becomes low. .

  In step S <b> 305, the acceleration calculation unit 212 calculates the vehicle running acceleration a based on the change in the vehicle speed stored in the storage unit 222. That is, the running acceleration of the automobile is obtained by obtaining the amount of change between the currently calculated speed stored in the storage unit 222 and the previously calculated speed. The calculated traveling acceleration is stored in the storage unit 222.

In step S306, the road angle calculating means 213 and the acceleration a ₀ are applied to the motor vehicle measured by the acceleration sensor 221, calculates a difference between the traveling acceleration a of the motor vehicle calculated based on GPS positioning, the subsequent step In S307, the inverse sine of these is obtained, and the road surface angle θ is calculated. The road surface angle θ is obtained by the above equation (2).

  In step S <b> 308, the obtained road surface angle θ is stored in the storage unit 222.

  In subsequent step S309, the speed / distance calculation determination unit 211 refers to the accumulated travel distance stored in the storage unit 222 and determines whether or not the vehicle has traveled a predetermined distance since the previous correction value calculation. The predetermined distance is set to a relatively long distance such as 1000 km or 2000 km, for example. If it is assumed that there is no error in the acceleration sensor 221 when the vehicle travels such a long distance, the total and average values of the stored road surface angles should converge to zero, and the correction value of the acceleration sensor 221 is calculated. Convenient.

  In the above description, it is described whether or not the cumulative travel distance has reached the predetermined distance. However, the present invention is not limited to the above, and the number of cumulative road surface angle data stored in the storage unit 222 has reached the predetermined number. It may be determined whether or not. For example, the number of accumulated road surface angle data may be set as 360000. In this case, since road surface angle data is accumulated every second, it means that the vehicle has traveled 100 hours at a speed of 20 km / h or more, so the cumulative travel distance is at least 2000 km. Further, in addition to the number of data of the cumulative travel distance and the cumulative road surface angle, it may be determined whether or not the cumulative travel time has reached a predetermined time. The cumulative travel time is the time when the navigation device 200 is turned on. However, like the number of data of the accumulated road surface angle, only the time when it is detected that the speed is 20 km / h or more may be stored, and the accumulated traveling time may be used for determination.

  If it is determined in step S309 that the accumulated travel distance has not reached the predetermined distance, the process returns to step S301, and the processes from step S301 to step S309 are repeated.

  If it is determined in step S309 that the cumulative travel distance has reached the predetermined distance, the process proceeds to step S310, and the road surface angle calculating means 213 calculates the average value of the road surface angles. This is obtained by dividing the total value of road surface angles by the number of road surface angle data stored in the storage means 222.

  Next, the acceleration is calculated from the average value of the road surface angles calculated in step S311. The acceleration is expressed by the following equation (4).

a ₁ = g · sin θ ₁ (4)
Here, θ ₁ is an average value of the road surface angle.

The acceleration a ₁ obtained here corresponds to an error in acceleration detected when the automobile is traveling on a horizontal road surface, and corresponds to the correction value of the acceleration sensor to be obtained in this embodiment. In step S <b> 312, the calculated acceleration is stored in the storage unit 222 as a correction value of the acceleration sensor 221 and reflected in the subsequent processing or directly reflected in the output of the acceleration sensor 221. For example, the correction value is reflected by adding the calculated acceleration a ₁ to the output of the acceleration sensor 221.

  As described above, according to the navigation device of the embodiment, from the first acceleration detected by the acceleration sensor, the displacement of the current position detected by the GPS receiver or the like, or the change of the speed detected by the speed sensor. A parameter obtained from the calculated second acceleration is sequentially stored, and when the cumulative travel distance of the vehicle reaches a predetermined value, an average value of the parameter is calculated to obtain a correction value of the acceleration sensor. Can do. These are applied to accumulate the difference parameters obtained from the first acceleration and the second acceleration, and the more the vehicle travels, the more they converge to zero. As a result, the correction value of the acceleration sensor mounted on the vehicle is obtained regardless of whether the vehicle is positioned on a horizontal road surface or an inclined road surface, and whether the vehicle is running or stopped. It becomes possible.

In the above embodiment, the acceleration obtained from the average value of the calculated road surface angle is used as the correction value of the acceleration sensor. However, the present invention is not limited to this. For example, the acceleration is measured by the acceleration sensor without calculating the road surface angle. The same effect can be obtained by using the average value of the difference between the acceleration a _{0 applied} to the automobile and the running acceleration a of the automobile calculated based on GPS positioning as the correction value of the acceleration sensor.

DESCRIPTION OF SYMBOLS 20 Vehicle 200 Navigation apparatus 210 Control means 211 Speed / distance calculation determination means 212 Acceleration calculation means 213 Road surface angle calculation means 214 Route search means 215 Route guidance means 220 GPS receiver 221 Acceleration sensor 222 Storage means 223 Map storage means 224 Display means 225 Input means 226 Audio output means

Claims (8)

An acceleration sensor for measuring a first acceleration applied to a vehicle, and a correction device for an acceleration sensor connected to a position detection means or a speed sensor installed in the vehicle,
The acceleration sensor correction apparatus includes a control unit and a storage unit.
The control unit calculates a second acceleration based on an output from the position detection unit or the speed sensor, and sequentially stores parameters obtained from the first acceleration and the second acceleration in the storage unit. When the cumulative travel history of the vehicle reaches a predetermined value, a correction value is calculated based on the stored parameter, and the acceleration sensor is corrected using the correction value. Correction device.   The acceleration sensor correction device according to claim 1, wherein the parameter is a difference between the first acceleration and the second acceleration.   The acceleration sensor correction apparatus according to claim 2, wherein the control unit calculates an average value of the parameters as the correction value.   The acceleration sensor correction device according to claim 1, wherein the parameter is an inclination of the vehicle obtained from a difference between the first acceleration and the second acceleration.   The acceleration sensor correction apparatus according to claim 4, wherein the control unit calculates an inclination of the vehicle by obtaining an arc sine from a difference between the first acceleration and the second acceleration.   The said control means calculates the said correction value by calculating the average value of the calculated vehicle inclination, and calculating | requiring the sine from the calculated average value of the vehicle inclination. 5. The correction device for an acceleration sensor according to 5.   The control means determines the parameter based on the first acceleration and the second acceleration when detecting that the speed of the vehicle is equal to or higher than a predetermined speed based on an output from the position detecting means or a speed sensor. The correction device for an acceleration sensor according to claim 1, wherein the correction device for acceleration sensor is calculated.   The acceleration sensor correction apparatus according to claim 1, wherein the cumulative travel history includes one or more of a cumulative travel distance, a cumulative travel time, and a cumulative parameter number.

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