JP2006098246A - Vehicle position detection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle position detection system which can perform correction processing in accordance with the reliability of a GPS signal and perform high-precision vehicle position detection. <P>SOLUTION: The vehicle position detection system comprises a GPS receiver 2 for receiving the GPS signal, a first calculation means for calculating a GPS position A(t) on the basis of the GPS signal, a distance detection means for detecting a travel distance of a vehicle, a direction detection means for detecting a travel direction of the vehicle, and a second calculation means for calculating a relative position R(t) on the basis of the travel distance detected by the distance detection means and the travel direction detected by the direction detection means. The vehicle position detection system further comprises a decision means for calculating the reliability of the GPS position and a correction means for correcting the relative position R by the GPS position A(t) in consideration of the reliability by the decision means and a calculation time by the first calculation means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle position detection device that measures the position of a host vehicle on a vehicle using a GPS (Global Positioning System) that receives radio signals from positioning satellites.

  Conventional methods for detecting the current position and traveling direction of a vehicle include a GPS positioning method and dead reckoning navigation (self-contained navigation). The GPS positioning method is a method of detecting the current position and traveling direction of a vehicle by receiving GPS signals sent from three or more satellites, and the accuracy of the GPS signal itself and the positional relationship between the artificial satellite and the vehicle are good. If so, an accurate current position and traveling direction can be obtained. Dead reckoning, on the other hand, detects the travel distance and travel direction of a vehicle based on various information obtained from detection means such as a vehicle speed sensor and a gyroscope, and based on those data, This is a method of detecting a current position by specifying a travel route of a vehicle by map matching.

Also, dead reckoning has a problem that the detection error accumulates as the travel distance increases because an error occurs in the sensor. Thus, dead reckoning navigation using the information (current position) obtained by the former GPS positioning method has occurred. There has been proposed a vehicle position detection device that corrects the current position obtained by the above (see, for example, Patent Document 1).
Japanese Patent Publication No.7-92388

  However, since such a vehicle position detection device requires a predetermined time from the reception of the GPS signal from each artificial satellite to the calculation and output of information such as the current position and the traveling direction, the information based on the GPS positioning method is used. If the current position is corrected by dead reckoning, the calculation error of the current position is increased due to the movement of the vehicle for the predetermined time.

  In addition, there is a problem that the reliability of the information by the GPS positioning method varies depending on the number and arrangement of positioning satellites, the level of signals (transmitted radio waves), and the like.

  Accordingly, an object of the present invention is to focus on the above-described problems, and is a vehicle position detection device that can perform highly accurate position detection by a correction process according to information reliability. Is to provide.

  The vehicle position detection device according to the present invention includes, as described in claim 1, a GPS reception unit that receives a GPS signal, a first calculation unit that calculates a first vehicle position based on the GPS signal, Based on the distance detection means for detecting the travel distance of the vehicle, the orientation detection means for detecting the travel direction of the vehicle, the travel distance detected by the distance detection means, and the travel direction detected by the orientation detection means. A vehicle position detection device comprising: a second calculation means for calculating a second vehicle position; a determination means for calculating the reliability of the first vehicle position; the reliability by the determination means; Correction means for correcting the second vehicle position based on the first vehicle position in consideration of the calculation time of the first calculation means.

  In addition, as described in claim 2, in the vehicle position detection device according to claim 1, the determination unit includes the first vehicle according to a moving speed of the GPS reception unit and an arrangement state of positioning satellites. The reliability of the position is calculated.

  Further, as described in claim 3, in the vehicle position detection device according to claim 1, the correction unit includes the reliability of the first vehicle position calculated by the determination unit, and the distance detection unit. The second vehicle position is corrected by performing a Kalman filter process using a Kalman gain calculated according to the travel distance of the vehicle and the traveling direction of the bearing detection unit. .

  The present invention includes a GPS receiving means for receiving a GPS signal, a first calculating means for calculating a first vehicle position based on the GPS signal, a distance detecting means for detecting a travel distance of the vehicle, and the vehicle Direction detecting means for detecting the traveling direction of the vehicle, second calculating means for calculating the second vehicle position based on the traveling distance detected by the distance detecting means and the traveling direction detected by the direction detecting means With respect to the vehicle position detection device including the above, position detection with high accuracy can be performed by the correction process according to the reliability of information.

  Hereinafter, as an embodiment of the present invention, an example applied to a car navigation device will be described with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing an electrical configuration of the car navigation apparatus. The car navigation device is mounted on a vehicle, and includes a vehicle speed sensor (distance detection means) 1, a GPS receiver (GPS reception means) 2, a gyro sensor (azimuth detection means) 3, a storage medium 4, and a control means 5. , And display means 6.

  For example, the vehicle speed sensor 1 is attached to a transmission of a vehicle, generates a predetermined number of pulse signals per one rotation of a pinion for a speedometer, and outputs the pulse signal to the control means 5. The control means 5 calculates the travel speed of the vehicle by detecting the number of pulses or the pulse period per unit time output from the vehicle speed sensor 1, and calculates the travel distance of the vehicle by counting the number of pulses. To do.

  The GPS receiver 2 is a receiver that receives a GPS signal emitted from an artificial satellite, and detects the current position and traveling direction of the vehicle based on the received GPS signal. A GPS reception antenna and an amplification circuit are provided, and a signal obtained by amplifying a transmission radio wave as position information from an artificial satellite received by the reception antenna as a high frequency signal is output to the control means 5.

  The gyro sensor 3 detects the turning angular velocity of the vehicle and outputs it to the control means 5. The control means 5 calculates the turning angle of the vehicle based on the turning angular velocity detected by the gyro sensor 3, and further calculates the traveling direction of the vehicle by integrating the turning angle. In addition, the traveling direction of the vehicle calculated based on the output of the gyro sensor 3 can be corrected in a timely manner based on the accurate traveling direction of the vehicle detected by the GPS receiver 2.

  The storage medium 4 is configured by a CD-ROM, DVD-ROM, hard disk, or the like, and is a storage device that stores road map data. The road map data is used when processing described later by the control means 5 is performed. The control means 5 counts the output pulse signal of the vehicle speed sensor 1 to detect the travel distance of the vehicle, detects the travel direction of the vehicle based on the turning angular velocity of the gyro sensor 3, and based on the travel distance and travel direction. To calculate the running trajectory. Then, the control means 5 compares the travel locus with the road map data read from the storage medium 4 and performs map matching to calculate the estimated position of the vehicle.

  The control means 5 can be a microcomputer, and includes a ROM that stores a control program for arithmetic processing operations, a RAM that temporarily stores arithmetic values, an EEPROM that stores various preset values, and the control It is mainly configured by a CPU for executing a program and an input / output interface circuit. The input / output interface circuit is a circuit for establishing an electrical connection with the vehicle speed sensor 1, the GPS receiver 2, the gyro sensor 3, the storage medium 4, and the display unit 6. The control means 5 outputs a control signal to the display means 6 based on the input from each mechanism (1 to 4) and the control program, and prompts a desired display. The control means 5 can perform arithmetic processing as first and second calculation means, distance detection means, azimuth detection means, determination means, and correction means in a control program described later.

  The display means 6 is composed of, for example, a display device composed of a TFT-type liquid crystal display panel and a display drive circuit composed of an IC or LSI for driving the display device. The display means 6 performs a desired display such as a road map based on a signal from the control means 5.

  With the above configuration, the control means 5 calculates the travel distance, traveling direction, and position coordinates of the vehicle based on the detection of the vehicle speed sensor 1, the gyro sensor 3, and the GPS receiver 2, and around the estimated position of the vehicle. Corresponding road map data can be read from the storage medium 4 and displayed on the display means 6.

  Next, the calculation process of the estimated position of the vehicle by the control means 5 will be described with reference to FIGS. FIG. 2 is a flowchart showing a control program by the control means 5 when a GPS signal is received. FIG. 3 is a diagram showing a locus of the relative position R used when calculating the estimated position P of the vehicle. The relative position R is calculated from the GPS position A calculated from the GPS signal, the relative movement vector V calculated from the travel distance and the traveling direction, the past estimated position P, and the past relative position R. In this case, 1 Updated every second. Further, the relative position R and the relative movement vector V calculated within a predetermined time are stored in the RAM of the control means 5 as needed.

  As a first calculation means, the control means 5 requires a predetermined time (for example, about 3 seconds) from the reception of the GPS signal by the GPS receiver 2 and is a GPS position (first vehicle position) that is the absolute position of the vehicle. A (t) is calculated (step S1).

  The control means 5 counts the pulse signal output from the vehicle speed sensor 1 as the distance detection means, calculates the travel distance, and integrates the turning angular velocity output from the gyro sensor 3 as the direction detection means. The turning angle is calculated, the turning angle is added to the previously calculated traveling direction to calculate the current traveling direction, and the relative movement vector V (t) is calculated based on the travel distance and the traveling direction information. (Step S2).

  Further, the control means 5 serves as a determination means, the value of the relative movement vector V (t) calculated in step S2, the DOP (Dilution of Precision) value calculated based on the GPS signal, and the GPS receiver 2. Based on the moving speed, a Kalman gain is calculated in consideration of the reliability of the GPS position A (t) (step S3).

  Note that the greater the vehicle travel distance and rotation angle, which are the parameters of the relative movement vector V (t), the greater the measurement error that occurs in the vehicle speed sensor 1 and the gyro sensor 3, and the greater the rotation angle such as a sharp curve or right / left turn. In this case, the GPS signal reception state becomes unstable, and the reliability of the GPS signal received at this time is lowered. The DOP value is obtained by the reciprocal of the area of the polyhedron with each positioning satellite and the GPS receiver 2 as vertices, and the GPS position (absolute position) at which the positioning is performed around the true position of the vehicle varies. Represents. Therefore, the reliability of the GPS position A (t) decreases as the DOP value increases. Also, the smaller the moving speed of the GPS receiver 2, the smaller the deviation of the tuning frequency of the GPS signal due to the Doppler effect, so the error in absolute position calculation increases and the reliability of GPS position A (t) decreases. End up. In step S <b> 3, the control unit 5 calculates the Kalman gain using a calculation formula that takes into account the degree of decrease in the reliability of the GPS signal as described above.

  Next, the control unit 5 serves as a correction unit with respect to the relative position R (t−3) calculated before a predetermined time (for example, 3 seconds) among the relative positions R stored in the RAM and calculated in the past. Then, the Kalman filter process is used to correct by using the Kalman gain calculated in step S3 to obtain the relative position R ′ (t−3) (step S4). Note that the control means 3 considers the calculation time of the GPS signal A (t) in step S1, and uses the relative position R (t-3) calculated at a time close to the time of receiving the GPS signal as a correction target. .

  The control means 5 uses the relative movement vectors V (t−2), V calculated in the past (2 seconds before and 1 second before) with respect to the relative position R ′ (t−3) corrected in step S4. (T-1) is read from the RAM of the control means 5 and added to obtain the relative position R (t-2) two seconds ago and the relative position R (t-1) one second ago (step S5). .

  In addition, the control means 5 uses the vehicle existence probability (probability at the time of map matching) at the estimated position P (t−1) calculated last time, the estimated position counter (counter of the number of probable determinations), and step S2. Based on the calculated relative movement vector V (t), a Kalman gain for the relative position R (t−1) is calculated (step S6).

  Next, the control means 5 corrects the position of the relative position R (t−1) obtained in step S5 based on the Kalman gain obtained in step S6 (step S7). In this case, the position is corrected to the relative position R ′ (t−1) obtained by moving the position corresponding to the correction amount δ. Further, the relative position R ′ (t−2) obtained in step S6 is corrected by the correction amount δ to obtain the relative position R ′ (t−2), and the relative position R ′ (t−1). ) And stored in the RAM of the control means 5.

  As the second calculation process, the control means 5 adds the relative movement vector V (t) calculated in step S2 to the corrected R ′ (t−1) obtained in step S7. The relative position R (t) is calculated (step S8).

  The control means 5 reads the road map data of the storage medium 5 and considers the relative position (second vehicle position) R (t) calculated in step S8 and the distance to each road, the traveling direction, and the like. Then, the map matching process is performed to obtain an estimated position P (t) with a high probability that an actual vehicle exists (step S9).

  By repeating the control program described above, it is possible to obtain a more probable estimated position P while correcting the past relative position R in consideration of the GPS signal for the position of the vehicle. Further, each time the estimated position P is updated, the control means 5 can draw a road map corresponding to the estimated position P and display it on the display means 6.

  Such a car navigation apparatus includes a GPS receiver 2 that receives a GPS signal, a first calculation means (control means 5) that calculates a GPS position A (t) based on the GPS signal, and a travel distance of the vehicle. Distance detecting means (control means 5) for detecting, direction detecting means (control means 5) for detecting the traveling direction of the vehicle, travel distance detected by the distance detecting means, and traveling direction detected by the orientation detecting means And a second calculation means (control means 5) for calculating the relative position R (t) based on the determination means (control means) for calculating the reliability of the GPS position. 5) and correction means (control means 5) for correcting the relative position R with the GPS position A (t) in consideration of the reliability of the determination means and the calculation time of the first calculation means. . Accordingly, it is possible to perform a correction process according to the reliability of the GPS signal while considering the calculation time from when the GPS receiver 2 receives the GPS signal until the absolute position (GPS position A) is calculated, A vehicle position detection device capable of detecting the position of the vehicle with high accuracy is provided.

  In the embodiment of the present invention, description has been given by taking as an example the case where each step of the control program is performed by the same control means 5, but the microcomputer is mounted on a separately provided circuit board. The control program may be distributed, for example, the GPS position, the DOP value, the moving speed of the GPS receiver, etc. are calculated by a microcomputer built in the GPS receiver and output to the control means. It may be a configuration.

The block diagram which shows the electrical structure in embodiment of this invention. The flowchart which shows the control program in embodiment same as the above. The figure which shows the locus | trajectory of the estimated position and relative position in embodiment same as the above.

Explanation of symbols

1 Vehicle speed sensor (distance detection means)
2 GPS receiver (GPS receiving means)
3 Gyro sensor (direction detection means)
5 Control means A GPS position (first vehicle position)
R Relative position (second vehicle position)
V relative movement vector

Claims (3)

GPS receiving means for receiving a GPS signal; first calculating means for calculating a first vehicle position based on the GPS signal; distance detecting means for detecting a travel distance of the vehicle; and detecting a traveling direction of the vehicle And a second computing means for computing the second vehicle position based on the travel distance detected by the distance detecting means and the traveling direction detected by the azimuth detecting means. A position detecting device,
The second vehicle position is determined by the first vehicle position in consideration of the determination means for calculating the reliability of the first vehicle position, the reliability by the determination means and the calculation time by the first calculation means. Correction means for correcting the vehicle position detection means.   The vehicle position detection device according to claim 1, wherein the determination unit calculates the reliability of the first vehicle position according to a moving speed of the GPS reception unit and an arrangement state of positioning satellites. The correction means is a Kalman calculated according to the reliability of the first vehicle position calculated by the determination means, the travel distance by the distance detection means, and the traveling direction by the direction detection means. The vehicle position detection device according to claim 1, wherein the second vehicle position is corrected by performing a Kalman filter process using a gain.

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