JP3112405B2 - Vehicle position detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a vehicle position detecting device used for a vehicle-mounted navigation device.

[0002]

2. Description of the Related Art A navigation device calculates a route on which a moving object such as an automobile has traveled, and displays a current position of the vehicle on a map screen displayed on a display device.
It is a device that assists the driver. The current position of the vehicle is measured by, for example, a GPS (Global Positioning System). GPS cannot be used in places such as tunnels where signals from positioning satellites cannot be received. Therefore, it is difficult for the GPS receiver alone to always detect the current position and traveling direction of the vehicle.

In recent years, a so-called hybrid type position detecting device including a position detecting mechanism using a GPS receiver and a position detecting mechanism for performing dead reckoning navigation, which has two systems, has been used in a navigation device. Many hybrid position detecting devices have a configuration in which when it is difficult for one position detecting device to accurately detect a position, the other position detecting device compensates for the position detection. For example, mainly using a position detection mechanism using a GPS receiver,
When the reception condition of the S receiver is deteriorating, or when the error of the measured current position is large, the current position of the vehicle is measured by dead reckoning navigation. Dead reckoning is a method of estimating a relative current position of a vehicle from a traveling distance and a relative traveling direction. The traveling direction is a direction along the traveling direction of the vehicle when passing through the current position.

In some cases, dead reckoning is mainly used, and an error in a relative position estimated by dead reckoning is converged by using an absolute position measured by a GPS receiver. Furthermore, in addition to a GPS receiver and a position detecting mechanism such as dead reckoning, there is an apparatus that performs a position correction process called a map matching process. In the map matching process, the traveling locus of the vehicle is detected, the traveling locus is compared with the road shape around the current position of the vehicle, and the current position of the vehicle is corrected on a road having a similar traveling locus and road shape. . That is, the position of the vehicle is corrected on the assumption that the vehicle always travels on the road.

Japanese Patent Laid-Open Publication No. Sho 62-272115 discloses a technique for correcting an azimuth signal measured by a magnetic compass using GPS. GP of the present invention
In the S-navigation device, when the traveling speed exceeds a set value while the moving body is traveling, the azimuth information from the GPS reception position calculation device and the azimuth information from the magnetic compass are compared. When there is an error in the two azimuth information, the magnitude of the azimuth signal output from the magnetic compass is adjusted based on the azimuth signal output from the reception position calculation device, and the information error is corrected to be zero.

Japanese Unexamined Patent Publication No. Hei 3-23491 discloses a technology related to an on-vehicle navigation device provided with a geomagnetic sensor for detecting the traveling direction of the vehicle and a GPS device for detecting the absolute position of the vehicle. In the in-vehicle navigation device of this publication, when it is detected that the output data of the geomagnetic sensor is abnormal, the output data of the geomagnetic sensor is taken in as a correction data after the output data of the geomagnetic sensor is stabilized after the abnormality is detected. Further, the absolute azimuth of the vehicle is obtained based on the output data of the GPS device, and the output data of the geomagnetic sensor is corrected using the correction data and the absolute azimuth. The abnormality in the output data of the geomagnetic sensor is determined, for example, based on whether or not the azimuth difference between the traveling azimuth of the vehicle detected by the geomagnetic sensor and the absolute azimuth detected by the GPS device exceeds a predetermined value.

[0007] Such a navigation device and GP
The S-navigation device detects the traveling direction of the vehicle using geomagnetism such as a geomagnetic sensor and a geomagnetic compass. The geomagnetic sensor generates an error when the geomagnetism is disturbed by a large vehicle passing on the side of the vehicle. Also, an error occurs when the vehicle passes over a ferromagnetic material such as a railroad crossing. Furthermore, when the body of the vehicle is magnetized, an error always occurs. As described above, when the traveling direction is detected using geomagnetism, there is a large possibility that an error due to an external factor occurs.

The applicant of the present application has proposed in Japanese Patent Laid-Open Publication No. 4-172214 a technique relating to an azimuth sensor that uses a geomagnetic sensor and a rate type azimuth sensor in combination and maintains a good detection angle over a long time range. I have. The azimuth sensor calculates a corrected azimuth by performing a weighted average of the azimuth output from the geomagnetic sensor and the azimuth output from the rate type azimuth sensor. This corrected direction is used as a reference direction of the rate type direction sensor. The rate type azimuth sensor detects the rotation speed, calculates the rotation speed from the reference azimuth, adds the rotation to the given reference azimuth, and outputs the azimuth. The weighting coefficient in the weighted average is determined based on a function of the traveling time of the object to which the direction sensor is attached. The weighting coefficient is obtained by a function using the temperature of the direction sensor or the temperature around the direction sensor as a parameter.

Japanese Unexamined Patent Publication No. Sho 59-218913 discloses a moving direction detecting system in which a geomagnetic sensor and a rate sensor are provided side by side, and the outputs of the sensors are weighted and then combined to detect the moving direction of the moving body. Is disclosed. In the detection method disclosed in this publication, a detection angle detected by a rate sensor and a detection angle detected by a geomagnetic sensor are weighted using a correction coefficient and then combined. The time variation of the correction coefficient is set in advance in accordance with, for example, the moving state of the automobile. Further, when the non-stop running time of the automobile becomes longer, the ratio of the rate sensor in the angle synthesis of the rate sensor is reduced and the ratio of the geomagnetic sensor is increased in proportion to the non-stop running time.

[0010]

The rate sensor (gyro) used in the moving direction detecting method described above is
Characteristics such as the offset of the output signal change with time due to a temperature change or the like. In order to remove this offset, the gyro according to the prior art detects that the vehicle speed of the vehicle has become zero, and performs zero correction based on the value of the output signal at that time. At this time, if the vehicle speed to be detected by the vehicle speed sensor cannot be obtained, the gyro zero point correction cannot be performed. If the zero point correction is not performed, the offset of the output signal will continue to change with time, and the gyro error will increase. In gyro,
Since the relative azimuth is estimated by accumulatively adding the measured turning amounts, a minute error included in each turning amount is accumulated, and the error increases.

The vehicle speed sensor is mounted, for example, near an axle that applies a rotational force to wheels of the vehicle. The travel distance is calculated from the number of pulses output when the axle rotates by a predetermined rotation angle and the unit travel distance of the vehicle per pulse. At this time, the number of pulses output per one rotation of the tire differs depending on the vehicle type. Also, in the same vehicle type, if the size of the tire to be mounted is different, the unit movement distance is different. Therefore, before obtaining the travel distance, it is necessary to drive the vehicle in advance to learn the unit travel distance, or to set the unit travel distance by the user of the navigation device.

In order to perform dead reckoning navigation, it is necessary that the gyro for detecting the relative azimuth of the vehicle has reached a state where the gyro can detect the azimuth. Further, it is necessary that the vehicle speed sensor that detects the traveling distance of the vehicle is in a state where the traveling distance can be detected. As described above, it is difficult to perform dead reckoning when the gyro and the vehicle speed sensor are not in a state where they can be used reliably.

It is an object of the present invention to provide a vehicle position detecting device capable of detecting a current position of a vehicle even when a configuration required for performing dead reckoning such as a gyro and a vehicle speed sensor cannot be used.

[0014]

SUMMARY OF THE INVENTION The present invention relates to an absolute position detecting means for detecting an absolute current position of a vehicle, and an absolute position detecting means for detecting an absolute traveling direction corresponding to the traveling direction of the vehicle at the current position. An azimuth detecting means, a traveling distance detecting means for detecting a traveling distance traveled by the vehicle, and a relative azimuth detecting means for detecting a relative traveling azimuth corresponding to the traveling direction; A vehicle position detecting device having a function of estimating a current position and a traveling direction of a vehicle in response to outputs from a vehicle, a traveling distance detecting device, and a relative bearing detecting device, wherein a traveling distance is calculated based on a detection value from the absolute position detecting device. When the difference between the traveling distance and the traveling distance detected by the traveling distance detecting means is equal to or larger than a predetermined value, it is determined that the detection value from the traveling distance detecting means is not valid. And determining the current position and heading of the vehicle based only on the outputs from the absolute position detecting means and the absolute azimuth detecting means when it is determined that the detection value from the traveling distance detecting means is not valid. And a position and orientation estimating means. According to the present invention, the vehicle position detecting device determines the current position and the traveling direction of the vehicle based on the output of the detecting means. For example, the vehicle position detecting device includes an absolute position detecting unit, an absolute azimuth detecting unit, a traveling distance detecting unit, and a relative azimuth detecting unit. The absolute position detecting means is realized by, for example, a GPS, and detects a current position which is an absolute current position of the vehicle. The absolute azimuth detecting means is realized by, for example, a GPS and a geomagnetic sensor,
An absolute heading, which is an absolute heading heading, is detected. The traveling direction indicates the traveling direction of the vehicle at the moment when the vehicle has passed the current position, and corresponds to the traveling direction of the vehicle. The travel distance detecting means detects a travel distance traveled by the vehicle. The travel distance is detected based on the amount of rotation of the vehicle wheels, for example, using a vehicle speed pulse signal output from a vehicle speed sensor.
The relative azimuth detecting means detects a relative azimuth which is a relative traveling azimuth corresponding to the traveling direction. The relative azimuth is obtained by detecting a turning amount when the vehicle turns, and accumulating the turning amount. The vehicle position detecting device estimates the current position and traveling direction of the vehicle based on the outputs of these detecting means. This device mainly uses a traveling distance detecting means and a relative azimuth detecting means, and corrects outputs from these detecting means by outputs of the absolute position detecting means and the absolute azimuth detecting means. That is, the vehicle position detecting device performs so-called dead reckoning navigation, and corrects the guessed result based on the absolute position and the absolute azimuth. When a configuration pre-mounted on a vehicle is used as the traveling distance detecting means, the format of an output signal output from the configuration corresponding to the traveling distance may differ from vehicle to vehicle. For example, when a vehicle speed sensor is used, the number of pulses output during one rotation of the wheel may differ for each vehicle speed. Therefore, when the vehicle position detecting means performs position detection using the vehicle speed sensor, it is not possible to calculate an accurate traveling distance until a unit traveling distance per pulse is set. The relative azimuth detecting means detects, for example, the amount of turning in the turning operation of the vehicle, and detects the relative azimuth by cumulatively adding the amount of turning. In this detection means, unless the absolute azimuth of the vehicle is given at least once as a reference, a traveling azimuth based on, for example, north cannot be specified. In a gyro, the turning amount is often output in accordance with the level change of the electric signal. Depending on the configuration of the gyro, the reference point at this level changes with time, so the reference point is sometimes corrected. Although the correction of the reference point is generally performed when the vehicle is stopped, on a highway or the like, the time interval at which the vehicle stops is long and the reference point correction is not easily performed. Therefore, the deviation of the reference point increases, and the output error increases. In the vehicle position detecting device of the present invention, the validity of the detected value from the traveling distance detecting means or the relative azimuth detecting means is determined by comparing the detected values from the respective detecting means. That is, it is determined whether or not the relative position and relative orientation obtained by dead reckoning are correct enough to be used for navigation. The position / azimuth estimating means estimates the current position and heading of the vehicle based only on the outputs from the absolute position detecting means and the absolute azimuth detecting means when the determining means determines that the detection value from the traveling distance detecting means is not valid. I do.
As described above, the vehicle detection device of the present invention estimates the current position and the traveling direction of the vehicle by correcting the relative position and the relative direction obtained by dead reckoning with the absolute position and the absolute direction. When dead reckoning cannot be performed, the current position and the traveling direction of the vehicle are estimated based only on the absolute position and the absolute direction. As a result, for example, even when the reference azimuth and the unit traveling distance required for performing dead reckoning are not given to the device, the current position and the traveling azimuth of the vehicle can be estimated. Further, for example, even when the gyro reference point is not corrected for a long time, the current position and the traveling direction of the vehicle can be estimated. Therefore, the current position and the traveling direction can always be presented to the user regardless of the state of each detecting means of the device.

[0015]

The determining means first calculates the traveling distance based on the detection value from the absolute position detecting means. Next, a difference between the traveling distance and the traveling distance detected by the traveling distance detecting means is obtained, and it is determined whether or not the difference is equal to or larger than a predetermined value. When the difference is equal to or greater than a predetermined value, it is determined that the detection value from the traveling distance detecting means is not valid.
For example, the traveling distance is detected from the rotation amount of the wheel based on the fact that the rotation amount of the wheel is proportional to the traveling distance. Therefore, when the vehicle travels on a gravel road or a snowy road and the wheels slip, the rotation amount of the wheels and the traveling distance are not proportional. Therefore, an error occurs in the traveling distance. The mileage obtained based on the absolute position is considered to substantially match the actual mileage of the vehicle. Therefore, the difference between the travel distance obtained based on the absolute position and the travel distance obtained from the travel distance detection means is regarded as an error of the travel distance of the detection means. When this error is large, it is considered that the error of the relative position obtained using this traveling distance also becomes large. At this time, the determining means determines that the detection value from the traveling distance detecting means is not valid. As a result, the position / azimuth estimating means can stop the estimating operation of the position / azimuth using the dead reckoning navigation and the absolute position and the absolute azimuth, and perform the estimating operation of the position / azimuth based only on the absolute position and the absolute azimuth. Thus, it is possible to converge the error of the current position of the vehicle accumulated up to the estimation operation. Therefore, it is possible to prevent the error from diverging due to an infinite increase in the error.

Further, the present invention provides an absolute position detecting means for detecting an absolute current position of the vehicle, an absolute azimuth detecting means for detecting an absolute traveling direction corresponding to a traveling direction in which the vehicle is traveling at the current position, A traveling distance detecting means for detecting a traveling distance traveled by the vehicle; and a relative bearing detecting means for detecting a relative traveling bearing corresponding to the traveling direction, the absolute position detecting means, the absolute bearing detecting means, and the traveling distance detection. A vehicle position detecting device having a function of estimating a current position and a traveling direction of the vehicle in response to outputs from the means and the relative azimuth detecting means, wherein the mileage detecting means detects a running state of the vehicle, and And a distance detection element that outputs a signal corresponding to the distance detection element, using a distance coefficient that is corrected based on a detection value from the absolute position detection means for an output signal of the distance detection element. A distance calculating means for calculating a line distance, wherein when the distance coefficient is outside a predetermined range, a determining means for determining that a detection value from the running distance detecting means is not valid; and And a position / azimuth estimating means for estimating the current position and traveling direction of the vehicle based only on the outputs from the absolute position detecting means and the absolute azimuth detecting means when it is determined that the detected value is not valid. It is a vehicle position detecting device. According to the invention, the traveling distance detecting means has a distance detecting element and a distance calculating means. The distance calculation element detects a traveling state of the vehicle and outputs a signal corresponding to the traveling distance. The distance detecting element is, for example, a vehicle speed sensor, and when an axle transmitting torque to the wheels rotates by a predetermined rotation angle,
Output pulse. The distance calculating means counts, for example, the number of pulses of the output signal of the distance detecting element, and calculates the travel distance using the distance coefficient. The distance coefficient is, for example, a conversion coefficient for converting an output signal indicating the amount of rotation of the wheel by the number of pulses into a travel distance. As described above, between the mileage detected by the mileage detection means and the actual mileage,
There are gaps due to wheel slips. Wheel slip varies depending on, for example, the state of the road on which the vehicle travels. For example, there are many slips on gravel roads and snowy roads. It also depends on whether the road is uphill or downhill. In order to take such changes into account, the distance coefficient is calculated based on the travel distance calculated based on the absolute position from the absolute position detection means, for example, every time the position and orientation estimation operation is performed. Corrected and updated. Therefore, when the distance coefficient is out of the predetermined range, that is, when the obtained value is abnormal, it is considered that the error of the obtained traveling distance increases. When this error is large,
It is considered that the error of the relative position obtained using this traveling distance also increases. Therefore, when it is determined that the distance coefficient corrected based on the detection value from the absolute position detection unit is outside the predetermined range, the determination unit determines that the detection value from the traveling distance detection unit is not valid. by this,
The position and direction estimating means can stop the operation of estimating the position and orientation using the dead reckoning navigation, the absolute position and the absolute direction, and perform the operation of estimating the position and orientation based only on the absolute position and the absolute direction. Thereby, even when the distance coefficient is out of the predetermined range, the operation of estimating the position and orientation can be executed.

The present invention also provides an absolute position detecting means for detecting an absolute current position of the vehicle, an absolute azimuth detecting means for detecting an absolute traveling direction corresponding to a traveling direction in which the vehicle is traveling at the current position, A traveling distance detecting means for detecting a traveling distance traveled by the vehicle; and a relative bearing detecting means for detecting a relative traveling bearing corresponding to the traveling direction, the absolute position detecting means, the absolute bearing detecting means, and the traveling distance detection. A vehicle position detecting device having a function of estimating a current position and a traveling direction of the vehicle in response to outputs from the means and the relative direction detecting means, wherein the relative direction detecting means detects a turning state of the vehicle and changes an angle of the vehicle. Azimuth detecting element that outputs a signal corresponding to the minute, and for the output signal of the azimuth detecting element,
Azimuth calculating means for calculating a relative azimuth using a sensitivity coefficient corrected based on the detection value from the absolute azimuth detecting means, when the sensitivity coefficient is outside a predetermined range,
Determining means for determining that the detection value from the relative bearing detecting means is not valid; and outputting from the absolute position detecting means and absolute bearing detecting means when the determining means determines that the detection value from the relative bearing detecting means is not valid. And a position and azimuth estimating means for estimating the current position and the traveling azimuth of the vehicle based solely on the vehicle position detecting device. According to the present invention, the relative azimuth detecting means further includes an azimuth detecting element and an azimuth calculating element. The azimuth detecting element is, for example, a gyro, and detects a turning state of the vehicle, and outputs a signal whose signal level increases or decreases in accordance with the angle change. The azimuth calculating means converts a signal level change into an angle change of the vehicle by using a sensitivity coefficient with respect to the output signal of the azimuth detecting element. This angle change is cumulatively added to the past relative azimuth to calculate the relative azimuth. The sensitivity coefficient is a so-called conversion coefficient. In a gyro, for example, if the temperature environment of the place where the gyro is installed changes, its characteristics may change. To take such changes into account,
The sensitivity coefficient is corrected and updated based on the absolute azimuth every time the position and azimuth estimation operation is performed. When the sensitivity coefficient is out of the predetermined range, that is, when the value of the update result is abnormal, it is considered that an error occurs in the converted relative orientation. When this error is large, it is considered that the error of the relative position obtained using this relative azimuth also becomes large. Therefore, when it is determined that the sensitivity coefficient corrected based on the detection value from the absolute azimuth detection means is outside the predetermined range, the determination means determines that the detection value from the relative azimuth detection means is not valid. As a result, the position / azimuth estimating means can stop the estimating operation of the position / azimuth using the dead reckoning navigation and the absolute position and the absolute azimuth, and perform the estimating operation of the position / azimuth based only on the absolute position and the absolute azimuth. Thus, even when the sensitivity coefficient is outside the predetermined range, the operation of estimating the position and orientation can be performed.

[0019]

FIG. 1 is a block diagram showing a functional configuration of a navigation device 1 according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating an electrical configuration of the navigation device 1. 1 and 2 will be described together.

The navigation apparatus 1 gives the estimated current position and the heading of the vehicle estimated by the position / azimuth estimating unit 3 at predetermined intervals to the map matching processing unit 4. The map matching processing unit 4 reads the road data related to the road near the estimated current position from the storage device 5 and places the estimated current position on the road represented by the road data and having a road shape similar to the traveling locus of the vehicle. Is performed in order to correct the map. The display map stored in the storage device 5 is read out separately from the road data, and is visually displayed in the visual display area of the display device 6. In addition, on the display map visually displayed, for example, a predetermined figure is displayed so as to be superimposed on a position corresponding to the corrected current position, which is a matching result of the estimated current position of the vehicle. Thereby, the current position of the vehicle recognized by the navigation device 1 is presented to the user of the device 1.

The position / azimuth estimating unit 3 includes, for example, an orientation sensor 11, a distance sensor 12, a GPS receiver 13, and a sensor signal processing circuit 14.

The direction sensor 11 detects the relative traveling direction of the vehicle and outputs its output to a sensor signal processing circuit 14.

The azimuth sensor 11 is realized by a device that outputs the rotation speed or rotation angular speed of a rotating body inside the device, such as a vibration gyro, an optical fiber gyro, and a gas rate sensor. When an output is provided from such a device, the sensor signal processing circuit 14 calculates the rotation angle or the rotation angular velocity from the reference point based on the output, and obtains the traveling azimuth by adding the rotation angle or the rotation angular velocity to the reference angle. When the vibrating gyroscope, the optical fiber gyroscope, the gas rate sensor, and the like are used, the calculated traveling direction is a relative direction. This relative orientation is given to the sensor signal processing circuit 14.

The distance sensor 12 is realized by, for example, a vehicle speed sensor. The vehicle speed sensor derives to the sensor signal processing circuit 14 a vehicle speed pulse signal that outputs a pulse every time the vehicle travels a predetermined unit traveling distance. The vehicle speed sensor
For example, it is mounted near a configuration such as an axle that applies torque to the wheels of a vehicle, and outputs a predetermined number of pulses per rotation per vehicle corresponding to the rotation angle at which this configuration rotates. . Sensor signal processing circuit 14
Counts the number of pulses of the output vehicle speed pulse signal by a counter, and determines the traveling distance of the vehicle based on the counted number of pulses. The mileage is determined by the sensor signal processing circuit 1
4 given.

The GPS receiver 13 measures the position coordinates of the current position of the vehicle. The GPS receiver 13 receives signals from at least four or more positioning satellites 15 out of a plurality of positioning satellites 15 orbiting the earth, and obtains the distance between each satellite 15 and the vehicle from a difference in arrival time of the signals. . From the obtained distance, absolute position coordinates such as the latitude and longitude of the current position of the vehicle are obtained based on triangulation. Therefore, GP
The current position of the vehicle output from the S receiver 13 is the absolute position of the vehicle.

Further, the GPS receiver 13 uses the Doppler effect in which the frequency of the signal from the positioning satellite 15 changes according to the moving direction when the vehicle is traveling at a speed higher than a predetermined speed. The absolute azimuth, which is the proper azimuth, is determined. That is, the absolute azimuth of the vehicle is determined from the positions of the vehicle and the positioning satellite 15 and the amount of change in the frequency of the signal. Further, the absolute azimuth of the vehicle may be measured by detecting a terrestrial magnetism on the earth using, for example, a terrestrial magnetism sensor. The absolute position and absolute azimuth determined in this way are given to the sensor signal processing circuit 14.

In the sensor signal processing circuit 14, when outputs from the sensors 11, 12 and the GPS receiver 13 are provided at predetermined intervals, a relative position which is a relative current position of the vehicle, and Estimate relative orientation.

The central processing unit 16 and the memory 17 include the sensor signal processing circuit 14 and the map matching processing unit 4
Also serves as a configuration. The outputs from the sensors 11 and 12 and the GPS receiver 13 and the estimated current position and traveling direction of the vehicle provided from the position and direction estimating unit 3 to the map matching processing unit 4 are stored in the memory 17. The central processing unit 16 performs various calculations using these input results and the road data from the storage device 15.

The storage device 5 records road data corresponding to various maps on a road data recording medium 19 for recording road data. The recording medium 19 also records the map data of the display map described above. The road stored in the recording medium 19 is simplified and represented as a line segment indicating only the length of the road and the direction in which the vehicle can travel. The direction in which the road can travel is referred to as a road direction. A road is configured by connecting a plurality of links that are line segments. The link has both ends, for example, at a corner of a road and an intersection, and this end is called a node.

The recording medium 19 is a CD-ROM, an IC,
This is realized by a configuration such as a card that is detachable from the storage device 5. Further, a non-detachable configuration such as a disk of a hard disk device may be used. The road data recorded on the recording medium 19 is read out using the road data reading device 20 and is read by the central processing unit 16 of the map matching processing unit 4.
Given to.

FIG. 3 is a flowchart for explaining the position / azimuth estimating operation performed in the sensor signal processing circuit 14 of the navigation device in FIG. In the navigation device 1 of the present embodiment, the absolute position of the current position of the vehicle and the absolute azimuth of the traveling direction of the vehicle are detected from the output of the GPS receiver 13. Further, based on the outputs from the direction sensor 11 and the distance sensor 12, the relative direction and travel distance of the traveling direction of the vehicle are detected. Sensor signal processing circuit 14
Then, the current position and the traveling direction of the vehicle are estimated by correcting the traveling distance and the relative direction with the absolute position and the absolute direction and performing dead reckoning using the correction result. Dead reckoning is a method of estimating a relative current position of a vehicle from a traveling distance and a relative traveling direction. When dead reckoning cannot be performed, the position and azimuth is estimated using only the absolute azimuth and the absolute position.

When the navigation device 1 is powered on and started, the process proceeds from step a1 to step a2. In step a2, initial setting of the estimation operation is performed. In the determination described later, 0 is substituted for each of the counters C1, C2, and C3 for counting the number of times an abnormality has occurred, and reset. The values of the counters C1, C2, and C3 are determination indices for determining whether to perform dead reckoning.
When the initial setting is completed, steps a2 to a3
Proceed to.

At step a3, it is determined whether or not the vehicle speed V of the vehicle is higher than a predetermined vehicle speed Vc. The vehicle speed V is obtained based on the absolute position and the absolute direction, that is, the output from the GPS receiver 13. The predetermined vehicle speed Vc is, for example, 10 km / h. Vehicle speed V
Is equal to or lower than the predetermined vehicle speed Vc, it is considered that the vehicle is almost stopped. When the vehicle speed falls below the predetermined vehicle speed Vc, the amount of change of the frequency of the signal from the positioning satellite 15 received by the GPS receiver 13 decreases,
It becomes difficult to detect the absolute azimuth. Therefore, when the vehicle is not running at a vehicle speed equal to or higher than the predetermined vehicle speed Vc, it is preferable to obtain the traveling direction of the vehicle by dead reckoning navigation. When the vehicle speed V of the vehicle is higher than the predetermined vehicle speed Vc and the absolute azimuth can be detected using the GPS receiver 13, the process proceeds from step a3 to step a4.

At step a4, it is determined whether or not the pulse number S of the vehicle speed pulse signal output from, for example, the direction sensor 11, which is a vehicle speed sensor, is zero. The pulse number S is, for example, the number of pulses included in the vehicle speed pulse signal output from the immediately preceding estimation operation to the latest estimation operation. When the pulse number S is 0, it is considered that the distance sensor 12, which is a vehicle speed sensor, is not normally operating. Also, some types of vehicles do not have a terminal for providing a vehicle speed pulse signal from a vehicle speed sensor attached to the vehicle to the navigation device. Also at this time, the pulse number S is counted as 0. If it is determined that the pulse number S is 0, the process proceeds from step a4 to step a5.

At step a5, the counter C1 is updated by adding 1 to it. The counter C1 is a counter for counting the number of times that it is determined that there is no vehicle speed input during traveling of the vehicle. When the counter C1 is updated, the process proceeds from step a5 to step a6. In step a6, it is determined whether the value of the counter C1 is larger than a predetermined value C1c.

For example, when the vehicle is stopped, GP
The vehicle speed V based on the output of the S receiver 13 may be erroneously higher than the predetermined vehicle speed Vc. G in such a case
When an estimation operation using only the output of the PS receiver 13 is performed,
The correct current position and heading of the vehicle cannot be estimated. Therefore, the sensor signal processing circuit 14 of the present embodiment
Then, it is determined that there is no vehicle speed input only when the vehicle runs at a vehicle speed Vc or higher and the number of times that the number S of vehicle speed pulses is 0 is equal to or greater than a predetermined number C1c. At this time, the position and orientation are estimated based only on the output of the GPS receiver 13.

When the vehicle speed V is equal to or lower than the predetermined vehicle speed Vc in step a3, and when the pulse number S is at least 1 in step a4,
Proceed to step a7. In step a7, it is determined that the vehicle speed has been input, and 0 is substituted for the counter C1 to reset. When the reset of the counter C1 ends, the process proceeds from step a7 to step a8. When the value of the counter C1 is equal to or smaller than the constant C1c in step a6, the process also proceeds to step a8.

At step a8, it is determined whether or not the moving distance Lg obtained based on the output from the GPS receiver 13 is longer than a predetermined moving distance Lgc. The movement distance Lg is, for example, a travel distance traveled by the vehicle between the immediately preceding estimation operation and the latest estimation operation. When the moving distance Lg is larger than the predetermined moving distance Lgc, it is determined that the output from the GPS receiver 13 can be used for estimating the position and orientation.

That is, the moving distance Lg is an index for determining the reliability of position detection using the GPS. Only when the reliability of the position detection using the GPS is high and the detected absolute position and absolute direction are determined to be valid, the GPS
Position detection based on only the output from the receiver 13 is allowed. When it is determined that the moving distance Lg is larger than the predetermined moving distance Lgc, the process proceeds from step a8 to step a9.

In step a9, it is determined whether or not the value of the distance difference ΔL is larger than a predetermined difference ΔLc. The distance difference ΔL is represented by the following equation.

ΔL = | Lg−Lv | (1) Lg is a moving distance calculated based on the output from the GPS receiver 13. Lv is the moving distance calculated based on the output from the distance sensor 12. These movement distances Lg and Lv are the travel distances that the vehicle has moved from the immediately preceding estimation operation to the latest estimation operation. When the distance difference ΔL is larger than the predetermined difference ΔLc, the distance sensor 12
Output is abnormal, and it is determined that the traveling distance is not correctly obtained. At this time, it is determined that the output from the distance sensor 12 is abnormal, and the process proceeds from step a9 to step a10.

For example, the distance sensor outputs a vehicle speed pulse in accordance with the rotation angle of the axle that applies a rotational force to the vehicle wheels. The sensor signal processing circuit 14 counts the number of output vehicle speed pulses, and determines the traveling distance on the assumption that the traveling distance is proportional to the rotation angle. At this time, if the wheels slip, the actual running distance of the vehicle and the rotation angle of the wheels are not proportional. At this time, the moving distance Lg of the GPS receiver 13 and the moving distance Lv of the distance sensor 12 are greatly different. Such a difference often occurs on a slippery road such as a gravel road or a snowy road.

At step a10, the counter C2 is updated by adding 1 to it. The counter C2 is a GPS receiver 13
Is a counter for counting the number of times the output from the distance sensor 12 is valid and the output from the distance sensor 12 is determined to be abnormal. When the updating of the counter C2 is completed, the process proceeds from step a10 to step all.

At step a11, it is determined whether or not the value of the counter C2 is larger than a predetermined constant C2c. If it is determined that the value of the counter C2 is equal to or smaller than the predetermined constant C2c, the process proceeds from step all to step a11.
Proceed to 13. In the sensor signal processing circuit 14, the counter C
2 only when it is determined that the value of 2 is larger than the constant C2c and the output of the distance sensor 12 is abnormal plural times continuously.
The position and orientation are estimated based only on the output from the PS receiver 13.

In step a8, the moving distance Lg
Is less than or equal to a predetermined moving distance Lgc, and when the value of the distance difference ΔL is less than or equal to a predetermined difference ΔLc,
Proceed to step a12. At this time, the traveling distance output from the distance sensor 12 is determined to be correct. Step a
At 12, the value of the counter C2 is substituted with 0 and reset. When the reset of the counter C2 is completed, step a
The process proceeds from step 12 to step a13.

When the output from the distance sensor 12 is given to the sensor signal processing circuit 14 and the traveling distance detected by the distance sensor 12 is judged to be correct, the step a13 is executed.
, A vehicle speed coefficient αn is obtained. The vehicle speed coefficient αn is a conversion coefficient for converting the traveling distance of the vehicle from the number of pulses of the vehicle speed pulse signal output from the distance sensor 12. The vehicle speed coefficient αn is represented by the following equation.

[0047]

(Equation 1)

Αn is a vehicle speed coefficient used in the latest estimation operation. α (n−1) is the vehicle speed coefficient used in the estimation operation immediately before the latest estimation operation. S is the number of pulses of the vehicle speed pulse signal output from the distance sensor 12 from the immediately preceding estimation operation to the latest estimation operation. Lg is a moving distance obtained based on the output from the GPS receiver 13. K1 is a weight coefficient.

As described above, the vehicle speed coefficient αn is updated each time the position and orientation estimation operation is performed. The vehicle speed coefficient αn is a unit moving distance corresponding to one pulse of the vehicle speed pulse signal, and differs for each vehicle type, for example. In addition, even in the case of the same vehicle type, if the diameters of the wheels to be mounted are different, they differ. Furthermore, the traveling distance converted from the number of pulses of the vehicle speed pulse signal may not match the actual traveling distance of the vehicle due to wheel slip or the like.

Therefore, in the sensor signal processing circuit 14, the moving distance Lv of the distance sensor 12 and the moving distance Lg of the GPS receiver 13 are weighted and added, respectively, and this addition result is divided by the pulse number S to obtain the latest. The vehicle speed coefficient αn in the estimation operation is obtained.

At this time, the weight coefficient K1 is set to 1 or less. When the position detection using the GPS receiver 13 cannot be performed, such as when the vehicle is stopped or when the signal from the positioning satellite 15 cannot be received, the weight coefficient K1 is set to 1. Furthermore, the weight coefficient K1 is set to increase as the traveling distance increases, for example. In addition, GPS receiver 1
The weight coefficient K1 may be increased as the reliability of the position detection performed by 3 increases. GP
The reliability of the S receiver 13 can be determined by a determination signal output from the GPS receiver 13, for example. The determination signal is determined based on, for example, the apparent position of the positioning satellite 15 that has received the position measurement signal, the received electric field strength of the signal, the number of positioning satellites 15 that have received the signal, and the like.

When the vehicle speed coefficient αn cannot be calculated, or when the calculated vehicle speed coefficient αn is uncertain, the estimation operation based on only the GPS receiver 13 may be performed. The vehicle speed coefficient αn is uncertain,
For example, when the value of the vehicle speed coefficient αn is out of the predetermined range. Also, when the parameters required for calculating the vehicle speed coefficient αn, such as the weight coefficient K1, the number of pulses S, and the moving distance Lg, cannot be obtained, it is also determined that the obtained vehicle speed coefficient αn is indeterminate.

When the calculation of the vehicle speed count is completed, step a
The process proceeds from step 13 to step a14. In step a14,
It is determined whether the azimuth difference Δθ is larger than a predetermined difference Δθc. The azimuth difference Δθ is obtained by the following equation.

Δθ = | θg−θv | (3) θg is the absolute azimuth of the vehicle obtained based on the output from the GPS receiver 13. θv is the relative azimuth of the vehicle obtained based on the output from the azimuth sensor 11.
When the azimuth difference Δθ is larger than a predetermined difference Δθc,
It is determined that the output from the direction sensor 11 is abnormal and the measured relative direction is not correct. At this time, GP
The operation of estimating the position and orientation is performed based on the output from the S receiver 13.

The direction sensor 11 is realized by, for example, a vibration gyro. Gyro-detected relative heading and GPS
Comparing the stability with the absolute direction detected by the receiver 13, the relative direction of the gyro is more stable in a short time. In a long time, the absolute azimuth from the GPS receiver is more stable. In addition, although the running azimuth detected by the gyro has a small error in one detection, if the detection is continued for a long time, the error is accumulated and increases. Although the GPS receiver 13 does not accumulate and increase the heading error, the GPS receiver 13 may not be able to measure when it reaches a position such as a tunnel where a signal from a positioning satellite cannot be received. In the sensor signal processing circuit 14, the direction sensor 1
The relative azimuth of No. 1 is corrected by the absolute azimuth of the GPS receiver 13, and the traveling azimuth of the vehicle is estimated.

When it is determined in step a14 that the azimuth difference Δθ is larger than the difference Δθc, the azimuth sensor 11
Is determined to be abnormal. At this time,
The process proceeds from step a14 to step a15. Step a
At 15, the counter C3 is updated by adding 1 to it. The counter C3 is a counter for counting the number of times that the output from the direction sensor 11 is determined to be abnormal. When the counter C3 is updated, the process proceeds from step a15 to step a16.

In step a16, it is determined whether the value of the counter C3 is larger than a predetermined constant C3c. When the value of the counter C3 is equal to or smaller than the constant C3c, the process proceeds to step a18.

When it is determined in step a14 that the azimuth difference Δθ is equal to or smaller than the predetermined difference Δθc, the process proceeds from step a14 to step a17. Step a17
Then, it is determined that the relative orientation of the orientation sensor 11 is correct. At this time, 0 is substituted for the counter C3 to reset. When the counter C3 is reset, step a1
The process proceeds from Step 7 to Step a18. When it is determined in step a16 that the value of the counter C3 is equal to or smaller than the predetermined constant C3c, the process also proceeds to step a18.

In step a18, the relative direction of the direction sensor 11 is corrected by the absolute direction of the GPS receiver 13. The corrected relative orientation θvn is obtained by the following equation.

Θvn = K2 × (θv (n−1) + Δθv) + (1−K2) × θg (4) θvn is the corrected relative azimuth of the latest vehicle. θv (n
-1) is the corrected relative orientation of the vehicle detected in the immediately preceding estimation operation. Δθv is an angle change of the relative orientation output from the orientation sensor 11 in the latest estimation operation. K2 is a weight coefficient. Thus, the latest corrected relative azimuth of the vehicle is the preceding traveling azimuth θv (n−
The relative azimuth is calculated by adding the latest angle change to 1), and the relative azimuth and the absolute azimuth θg of the GPS receiver 13 are calculated by weighting. At this time, the weight coefficient K2 is set to 1 or less. The weighting coefficient K2 is the same as the weighting coefficient K1 used for obtaining the vehicle speed coefficient αn.
May be changed according to the reliability of the data.

The output from the azimuth sensor 11 is given as, for example, an electric signal whose level increases or decreases around a predetermined value. Sensor signal processing circuit 1
4 converts the electrical signal into an angle using a conversion coefficient called a sensitivity coefficient. At this time, depending on the configuration of the direction sensor 11, the offset of the predetermined value serving as the center may change with time.

The azimuth sensor 11 performs zero point correction so that the output from the azimuth sensor 11 when the vehicle stops and the vehicle speed is 0 is set to a predetermined center value. When such zero point correction is not performed for a long time, the error of the output from the direction sensor 11 is considered to be extremely large. Therefore, when the zero point correction of the direction sensor 11 is not performed in a predetermined section, the position and direction may be estimated based on only the output from the GPS receiver 13. Further, even when a conversion coefficient such as a sensitivity coefficient is not determined, the position / azimuth estimation operation based on only the output from the GPS receiver 13 may be performed.

When the calculation of the bearing is completed, step a18
From step a19. In step a19, the position and orientation are estimated by dead reckoning navigation. First, step a
Using the vehicle speed count αn obtained in step 13, the pulse number S of the vehicle speed pulse signal is converted into the travel distance of the vehicle, and cumulatively added to the past travel distance to obtain the travel distance. The current position and the traveling direction of the vehicle are estimated based on the obtained traveling distance and the corrected relative direction θvn of the vehicle obtained in step a18. When the current position and traveling direction of the vehicle are obtained, the process returns from step a19 to step a3,
Next, it waits for outputs from the sensors 11 and 12 and the GPS receiver 13 to be given.

When the value of the counter C3 is larger than the predetermined constant C3c in step a16, it is determined that the relative direction of the direction sensor 11 is abnormal. In this case, the process proceeds from step a16 to step a20. The process also proceeds to step a20 when it is determined in step a6 that the value of the counter C1 is larger than the constant C1c, and when it is determined in step a11 that the value of the counter C2 is larger than the constant C2c. In step a20, the current position and traveling direction of the vehicle are estimated based only on the output from the GPS receiver 13. That is, the current position and the traveling direction of the vehicle are estimated from the absolute position and the absolute direction of the vehicle. When the estimation of the position and orientation is completed, the process returns to step a3.

As described above, in the sensor signal processing circuit 14,
When the outputs from the distance sensor 12 and the direction sensor 11 are abnormal, the position and direction are estimated using only the GPS receiver 13. Thus, even when the direction sensor 11 and the distance sensor 12 cannot be used, the current position and the traveling direction of the vehicle can be detected.

In dead reckoning navigation, the current position and traveling direction of the vehicle estimated in the past guessing operation are used as a reference.
Estimate the latest position and orientation. In the sensor signal processing circuit 14 of the present embodiment, the direction sensor 11 and the distance sensor 12
When the error of the output from the GPS receiver 13 increases, the mode is switched to the estimation of the position and orientation using the output from the GPS receiver 13. That is, when the error included in the current position and the traveling direction of the past vehicle becomes large, the current position and the traveling direction of the vehicle are estimated again from the absolute position and the absolute direction from the GPS receiver 13. Therefore, the latest current position and traveling direction serving as references in the next estimating operation do not include errors accumulated in the previous estimating operation. As a result, it is possible to prevent accumulation of errors and occurrence of error divergence. Therefore, the present position and traveling direction of the vehicle can be correctly estimated even when traveling on a rough road such as a snowy road or a gravel road where wheels are likely to slip.

[0067]

As described above, according to the present invention, the vehicle position detecting device has a plurality of detecting means, and corrects the relative position obtained from the traveling distance and the relative azimuth with the absolute position, thereby obtaining the current position of the vehicle. Guess. At the same time, the relative azimuth is corrected with the absolute azimuth, and the traveling azimuth of the vehicle is estimated. When the traveling distance becomes ineffective due to a large difference from the actual traveling distance or the like, the current position and the traveling direction of the vehicle are estimated based only on the absolute position and the absolute direction. That is, when the difference between the estimated relative position and the actual current position of the vehicle becomes so large that it cannot be used for navigation, the estimation of the position and orientation is performed based on the absolute position and the absolute orientation output from the detecting means with less error. Do.

Accordingly, even when the means for detecting the traveling distance cannot output a correct value,
The current position and traveling direction of the vehicle can be estimated.
Therefore, the current position and the traveling direction can always be presented to the user regardless of the state of each detecting means of the device.

[0069]

The determining means obtains a difference from the running distance from the running distance detecting means based on the running distance calculated based on the absolute position. When this difference is equal to or greater than a predetermined value and the error in the traveling distance from the detection means is large,
The operation of estimating the position and orientation is performed based only on the absolute position and the absolute orientation. Thus, in the next estimating operation, the current position is estimated based on the absolute position regarded as having a small error. Therefore, the error of the current position of the vehicle accumulated up to the estimation operation can be converged. Therefore, it is possible to prevent the error from diverging due to an infinite increase in the error. As a result, even when traveling on a road on which wheels are likely to slip, such as a snowy road and a gravel road, it is possible to reliably estimate the current position and traveling direction of the vehicle and continue navigation.

According to the invention, the traveling distance detecting means converts the output signal output from the distance detecting element by using the distance coefficient corrected based on the detection value from the absolute position detecting means, and Find the distance. When the corrected distance coefficient used for this conversion is out of the predetermined range, it is considered that the error of the obtained traveling distance increases and the relative position shifts. At this time, the operation of estimating the position and orientation using the dead reckoning navigation and the absolute position and the absolute direction is stopped, and the operation of estimating the position and orientation is performed based only on the absolute position and the absolute direction.
Therefore, even when a reliable traveling distance cannot be obtained, the operation of estimating the position and orientation can be performed. This allows navigation to continue.

Further, according to the present invention, the relative azimuth detecting means converts the angle signal output from the azimuth detecting element using a sensitivity coefficient corrected based on the detection value from the absolute azimuth detecting means, Obtain the angle change of the vehicle. By accumulatively adding the angle change, the traveling direction of the vehicle is obtained. When the corrected sensitivity coefficient used for this conversion is out of the predetermined range,
It is considered that an error occurs in the converted relative orientation, the error of the relative position increases, and the relative position shifts. At this time, the operation of estimating the position and orientation using the dead reckoning navigation and the absolute position and the absolute direction is stopped, and the operation of estimating the position and orientation is performed based only on the absolute position and the absolute direction. Therefore, even when a reliable traveling direction cannot be obtained, the operation of estimating the position and direction can be executed. Thereby, navigation can be continued.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a functional configuration of a navigation device 1 according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an electrical configuration of the navigation device 1.

FIG. 3 is a flowchart for explaining a position / azimuth estimating operation performed in the navigation device 1.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 navigation device 3 position / azimuth estimating unit 4 map matching processing unit 5 storage device 6 display device 11 direction sensor 12 distance sensor 13 GPS receiver 14 sensor signal processing circuit 19 road data recording medium 20 road data reading device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-311045 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01C 21/00-21/24

Claims (3)

(57) [Claims] 1. An absolute position detecting means for detecting an absolute current position of a vehicle, an absolute azimuth detecting means for detecting an absolute traveling direction corresponding to a traveling direction of the vehicle at the current position, and And a relative azimuth detecting means for detecting a relative traveling direction corresponding to the traveling direction. The absolute position detecting means, the absolute azimuth detecting means, the traveling distance detecting means and the relative In a vehicle position detecting device having a function of estimating a current position and a traveling direction of a vehicle in response to an output from an azimuth detecting means, a mileage is calculated based on a detection value from the absolute position detecting means, Determining means for determining that the detected value from the traveling distance detecting means is not valid when a difference from the traveling distance detected by the detecting means is equal to or greater than a predetermined value; When it is determined that the detection value from the traveling distance detecting means is not valid, a position and direction estimating means for estimating the current position and the traveling direction of the vehicle based only on the outputs from the absolute position detecting means and the absolute direction detecting means. A vehicle position detecting device comprising: 2. An absolute position detecting means for detecting an absolute current position of the vehicle, an absolute direction detecting means for detecting an absolute traveling direction corresponding to a traveling direction in which the vehicle is traveling at the current position, and the vehicle traveling And a relative azimuth detecting means for detecting a relative traveling direction corresponding to the traveling direction. The absolute position detecting means, the absolute azimuth detecting means, the traveling distance detecting means and the relative In a vehicle position detecting device having a function of estimating a current position and a traveling direction of a vehicle in response to an output from a direction detecting unit, the traveling distance detecting unit detects a traveling state of the vehicle and corresponds to the traveling distance. A travel distance is calculated by using a distance detection element that outputs a signal, and a distance coefficient that is corrected based on a detection value from the absolute position detection means with respect to the output signal of the distance detection element. Determining means for determining that a detection value from the traveling distance detection means is not valid when the distance coefficient is outside a predetermined range; and a detection value from the traveling distance detection means by the determination means. And vehicle position estimating means for estimating the current position and traveling direction of the vehicle based only on the outputs from the absolute position detecting means and the absolute direction detecting means when it is determined that the vehicle position is not valid. apparatus. 3. An absolute position detecting means for detecting an absolute current position of the vehicle, an absolute direction detecting means for detecting an absolute traveling direction corresponding to a traveling direction in which the vehicle travels at the current position, and the vehicle traveling. And a relative azimuth detecting means for detecting a relative traveling direction corresponding to the traveling direction. The absolute position detecting means, the absolute azimuth detecting means, the traveling distance detecting means and the relative In a vehicle position detecting device having a function of estimating a current position and a traveling direction of a vehicle in response to an output from a direction detecting unit, the relative direction detecting unit detects a turning state of the vehicle and responds to an angle change. A relative direction using a sensitivity coefficient corrected based on a detection value from the absolute direction detecting means with respect to an output signal of the direction detecting element. Azimuth calculating means for calculating, when the sensitivity coefficient is out of a predetermined range, determining means for determining that the detection value from the relative azimuth detecting means is not valid, and detecting value from the relative azimuth detecting means by the determining means And vehicle position estimating means for estimating the current position and traveling direction of the vehicle based only on the outputs from the absolute position detecting means and the absolute direction detecting means when it is determined that the vehicle position is not valid. apparatus.