JPH05215564A - Position measuring device for vehicle - Google Patents

Abstract

(57) [Summary] [Purpose] Installation angle error of INS (Inertial Navigation System),
Minimize the measurement error based on the scale factor error of the odometer (vehicle speed detector). [Structure] The vehicle runs straight for several tens of meters for several tens of seconds and then stops, and its starting point and arrival point are respectively INS.
Position, elevations N, E, and H calculated from the detected azimuth angle ψ, attitude angle θ, and the detected rotation number n of the odometer 24 multiplied by the scale factor, and the position measured by the GPS receiver 25. , The altitudes NG, EG, and HG are respectively compared and calculated, and the azimuth angle and attitude angle error δψ, δθ,
Obtain the scale factor error δA, and calculate INS with δψ and δθ.
The measured azimuth angle and posture angle ψ, θ are corrected respectively, and the scale factor is corrected by δA to be used for the subsequent position and altitude calculation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a vehicle in which an inertial navigation device for detecting an azimuth angle and an attitude angle, and a vehicle speed detector for detecting the rotational speed of wheels are mounted on a vehicle to measure the position of the vehicle. Position measuring device.

[0002]

2. Description of the Related Art First, an inertial navigation system mounted on a vehicle, a so-called INS, will be described with reference to FIG. 3A. INS
Is 3 gyros 11, 12, 13 and 3 accelerometers 1
4, 15 and 16 are attached to three orthogonal axes, respectively, and these gyro accelerometers are collectively referred to as a sensor 17. In addition to the sensor 17, the computer 18 and an interface 19 with an external device, and a power supply unit 21 for supplying power supply power necessary for operating each internal unit.

The gyros 11 to 13 detect the rotational angular velocity of the INS, and the accelerometers 14 to 16 detect the acceleration.
The computer 18 performs the following arithmetic processing on the obtained angular velocity and acceleration information. Calculation of posture angle θ = ∫ω _a dt + θ ₀ ω _a : Angular velocity in posture direction detected by INS gyro, θ ₀ : Calculation of initial posture angle and azimuth angle ψ = ∫ω _b dt + ψ ₀ ω _b : INS Azimuth angular velocity detected by gyro, ψ ₀ : initial azimuth angle horizontal acceleration a _H , vertical acceleration a _V calculation a _H = a _B cos θ a _V = a _B sin θ a _B : INS accelerometer The body-direction acceleration detected in step 3B is shown in FIG. 3B.
And the relationship between horizontal and vertical accelerations a _H and a _V in FIG.
Shown in B.

Calculation of horizontal velocity V _H V _H = ∫a _H dt Calculation of current position P P = ∫V _H dt + P ₀ P ₀ : Calculation of initial position vertical velocity V _V V _V = ∫a _V dt Calculation of altitude H H = ∫V _V dt + H ₀ H ₀ : Initial altitude In this way, the current position P and the altitude H can be measured only by INS. However, since the sensor 17 has an inherent error, the errors of velocity, position, and altitude increase with time due to the above-described integral calculations. Therefore, INS
The position error per hour is 1000m
Since it increases every 2000 m, it is not suitable for measuring vehicle position and altitude.

Therefore, it has been proposed to use the INS in combination with a vehicle speed detector, a so-called odometer. The odometer detects the number of rotations of the wheel,
Multiplying the circumferential length of the wheel gives the distance traveled. Using the mileage ΔL per unit time and the azimuth angle ψ and the attitude angle (pitch angle) θ detected by the INS, the northward distance ΔN, the eastward distance ΔE and the vertical distance ΔH per unit time.
Are calculated by the following calculations. These relationships are shown in Figure 3.
As shown in C and D.

ΔL _H = ΔL cos θ ΔH = ΔL sin θ ΔN = ΔL _H cos ψ ΔE = ΔL _H sin ψ ΔL _H : horizontal distance When these north distance ΔN and east distance ΔE are integrated,
A northward travel distance N and an eastward travel distance E from the starting point are obtained, respectively.

N = ∫ΔN dt (1) E = ∫ΔE dt (2) Similarly, when the vertical distance ΔH is integrated, the altitude change distance H from the starting point is obtained. These relationship diagrams are shown in FIG. 4A,
Shown in B. The above-mentioned calculations are performed by the computer 18 in the INS.
You can go in.

H = ∫ΔH dt ……… (3)

[0009]

SUMMARY OF THE INVENTION As described above, the conventional vehicle position elevation measuring apparatus has the azimuth angle ψ,
The position / elevation is calculated by regarding the attitude angle θ as the traveling direction of the vehicle. Therefore, when the INS has a mounting angle error with respect to the vehicle, an error occurs in the position / elevation measurement as described below. That is, as shown in FIG. 4C, when the INS is attached to the vehicle with an azimuth error δψ, the detected azimuth of the INS indicates δψ instead of 0 even if the vehicle travels to true north.
The calculation result of the position when the vehicle goes to the point A shows the point B. If the moving distance is L _H , the coordinates of point A are (0,
L _H) in spite of the position output (L _H sin δ
ψ, L _H cos δψ).

Further, as shown in FIG. 4D, when the INS is attached to the vehicle with an attitude angle error δθ, even if the vehicle travels horizontally, the detected attitude angle output of the INS shows δθ instead of 0. When the vehicle goes to the point C, the altitude calculation result shows the point D. If the moving distance is L, the altitude error is L sin δθ. On the other hand, it goes without saying that if there is an error in the scale factor (running distance per one revolution) of the odometer, an error will occur in the position output.

The present invention provides a vehicle position / altitude measuring device capable of highly accurately measuring position / elevation by automatically measuring and correcting the mounting angle error of the INS and the scale factor error of the odometer. To do.

[0012]

According to the present invention, a vehicle is equipped with a satellite navigation device (GPS: Global Positioning System), and the position measured by the GPS and the INS and the vehicle speed detector (odometer) are used for measurement. At least one of the mounting error angle of the INS and the scale factor error of the odometer is calculated from the calculated position by the error calculating means, and the calculated mounting error angle is IN.
The azimuth angle and the attitude angle detected in S are respectively corrected, and the scale factor of the vehicle speed detector is corrected by the calculated scale factor error. The position is calculated from the corrected azimuth angle and attitude angle, the scale factor, and the rotation speed detected by the vehicle speed detector.

[0013]

[Operation] A GPS receiver and a GPS antenna are mounted on the vehicle at least when measuring the mounting angle error of the INS and the scale factor error of the vehicle speed detector. Drive straight for a few tens of seconds from any given starting point and stop at any arriving point. At this time, by comparing the respective differences between the positions and altitudes measured by GPS at the two points with the respective differences between the positions and altitudes measured at the INS and the vehicle speed detector, the mounting angle error The magnitude of the scale factor error of the vehicle speed detector is calculated.

The GPS measurement position / elevation error is several tens of meters
There are several hundred meters. However, when the vehicle travels for several tens of seconds, the movement is only for several hundreds of meters. Therefore, if the GPS has an error of several tens of meters, the accuracy may be insufficient even if compared with the above, but it is solved by the following means. It First, GP
Since S satellites are far away from the ground, there are several 10
The measurement position and elevation error at two points 0 m apart are equal. In addition, the position / elevation error fluctuates slowly due to the movement of the satellite. However, in several tens of seconds, the magnitude of the fluctuation can be ignored. Therefore, the position and elevation error values at the start point and the arrival point are equal.
In order to measure the mounting angle error of the INS and the scale factor error of the vehicle speed detector, it suffices to know the relative position / elevation difference between the starting point and the arrival point, so that the absolute magnitude of the error does not matter. For that purpose, it is necessary to travel a long distance in a short time as much as possible.

[0015]

1A shows an embodiment of the present invention. In the present invention, a GPS receiver 25 and its antenna 26 are mounted on the vehicle in addition to the INS 23 and the vehicle speed detector (hereinafter referred to as odometer) 24. The sensor 17 of the INS 23 is shown in FIG.
About gyro 11-13, accelerometer 14-1
6 is provided, the posture of the
The azimuth calculation means 27 calculates the azimuth ψ of the INS and the attitude angle (pitch angle) θ. These ψ and θ are attached by the attitude and orientation mounting error correction calculation means 28, and the mounting error angles δθ and δψ.
Are respectively added and corrected.

Θ ′ = θ + δθ ψ ′ = ψ + δψ On the other hand, the rotational speed n of the wheel detected by the odometer 24
(Rotation / second) is multiplied by the scale factor (wheel diameter) of the odometer 24 in the scale calculation means 29 to obtain the speed of the vehicle (travel distance ΔL per unit time). In the normal case, the odometer 24 branches the cable from the engine to the speedometer to detect the number of revolutions of the propeller shaft. Therefore, the rotation speed n detected by the odometer 24
Different from the wheel rotation speed, it is necessary to correct the magnification for that purpose, but here, in order to facilitate understanding, it is assumed that the odometer 24 detects the wheel rotation speed. Further, the error δA of the scale factor A of the odometer 24 is corrected when the vehicle speed ΔL is calculated. Therefore, the following formula is calculated.

ΔL (m / s) = (1 + δA) A · n Using this vehicle speed ΔL and the corrected attitude angle θ ′ and azimuth angle ψ ′, the position / elevation calculation means 31 (1),
The vehicle position N, E, and altitude H are calculated by calculating the equations (2) and (3).
Are obtained and output. GPS receiver 25, GPS
The antenna 26 may be generally commercially available. The position output of an ordinary commercially available GPS receiver is performed in latitude and longitude, but the latitude and longitude can be easily converted to north and east coordinates. Therefore, the position N is north and east from the GPS receiver 25.
The G and EG and the altitude HG are output.

The outputs of this GPS receiver 25 are NG, EG,
HG and position, N, E, H calculated by the altitude calculation means 31
And the error δθ, δψ,
δA is calculated as follows. (1) Since the values of δθ, δψ, and δA are initially unknown, δθ = δ
Let ψ = δA = 0. (2) A position at an arbitrary starting point, N = N1, E = E1, and H = H1 are entered as initial output values of the altitude calculating means 31. The output of the GPS receiver 25 is NG = NG1, EG =
Record EG1, HG = HG1.

(3) Next, make the vehicle as straight as possible,
It runs for several hundred meters in a second and stops. At this time, the vehicle azimuth and pitch angle at the starting point must be the same as that of the vehicle at the arriving point. (4) Position at arrival point, output of altitude calculation means 31 N = N
2, E = E2, H = H2, and the output N of the GPS receiver 25
Record G = NG2, EG = EG2, HG = HG2.

(5) The error calculating means 32 performs the following calculation. These relationships are shown in FIGS. 1B and 1C.

[0021]

[Equation 1]

[0022]

[Equation 2] (6) The δθ, δψ, δA obtained in the item (5) are given to the posture / azimuth mounting error correction calculation means 28 and the scale calculation means 29, respectively, and used for the correction calculation. After that, highly accurate position and altitude data can be obtained without GPS. If the wheel mounting location is the same as the GPS antenna 26 mounting location, the wheel movement amount and the GPS antenna movement amount are always equal. However, as shown in FIG. 2A, the wheel 34 of the vehicle 33 and the antenna 26 are separated from each other, and the azimuth or pitch angle direction of the vehicle 33 is different between the starting point and the arriving point during traveling. The moving amount L of the wheel 34
_B (including the direction) is different from the moving amount L _A of the GPS antenna 26. The speed detected by the odometer 24 is the speed at the intermediate point between the left and right rear wheels.

In this case, the estimation accuracy of the INS mounting angle error and the odometer scale factor error naturally deteriorates. This problem can be solved by converting the position / elevation data of the output of the GPS receiver 25 into the position / elevation data of the wheel mounting location. That is, this conversion is performed by the conversion calculation means 35 as shown in FIG. 2B and given to the error calculation means 32.

As shown in FIG. 2C, the GPS antenna 26
The distance between the vehicle and the wheel location 36 is Y in the front-rear direction of the vehicle and X in the left-right direction. Output of GPS receiver 25 NG, EG, HG
Data NG ', EG', H converted to the wheel location 36
Assuming G ′, NG ′ and EG ′ can be obtained by the calculation of the following equation. NG ′ = NG−Y cos ψ + X sin ψ EG ′ = EG−Y sin ψ−X cos ψ Note that this equation does not consider the inclination of the vehicle 33.

If the height difference between the wheel location 36 and the antenna 26 is Z as shown in FIG. 2D, HG 'can be calculated by the following equation. HG ′ = HG−Y sin θ−Z cos θ Note that there is no inclination of the vehicle 33 in the roll direction.
By performing the above conversion, GPS data at the wheel location 36 can be obtained regardless of the azimuth and inclination of the vehicle 33.

Although both the INS mounting angle error and the odometer scale factor error have been corrected in the above description, only one of them may be corrected in some cases. Further, in the above description, the position of the vehicle and the altitude are measured, but only the position may be measured.

[0027]

As described above, according to the present invention, the GPS can be used to measure the mounting angle error of the INS or the scale factor error of the odometer, and can be corrected in the subsequent traveling. Therefore, highly accurate position / elevation Measurement becomes possible. It should be noted that if GPS is available, INS and odometer may be unnecessary, but as described above, GPS accuracy is several tens of meters or more.
The accuracy is several hundred meters, especially for inexpensive ones.
There is also. However, according to the present invention, even if such a low-precision GPS is used, the position / elevation error is 0.1% of the mileage.
It is possible to achieve high accuracy of 10m or less when traveling below, that is, 10km.

[Brief description of drawings]

FIG. 1A is a block diagram showing an embodiment of the present invention, B,
C is a diagram showing plane coordinates and vertical plane coordinates of the relationship between each calculation result of the position / elevation calculation means 31 at the starting point and the arrival point and each measurement value of the GPS receiver.

FIG. 2A is a diagram showing a difference in movement amount between a wheel and a GPS antenna, FIG. 2B is a block diagram showing a configuration for correcting an error based on the difference, and C and D are wheel locations and GPS antenna mounting, respectively. It is the top view and side view which show the relationship with a position.

FIG. 3A is a block diagram showing an outline of INS, and B is IN.
The figure which shows the relationship between the acceleration in the S body direction, and its horizontal and vertical components, C and D are the figures which show the vehicle speed (DELTA) L and its vertical component, the north component, and the east component, respectively. ..

[FIG. 4] A and B are diagrams showing a north component, an east component, and an altitude component which have respectively moved, and C and D are INS, respectively.
5 is a diagram showing a measurement position / elevation error based on the mounting angle error of FIG.

Claims (3)

[Claims] 1. Use of an azimuth angle and an attitude angle from an inertial navigation device mounted on a vehicle, and vehicle speed information obtained from a rotation speed of a wheel of the vehicle detected by a vehicle speed detector mounted on the vehicle. Then, in the vehicle position measuring device for measuring the position of the vehicle, the satellite navigation device mounted on the vehicle, the position measured by the satellite navigation device, the inertial navigation device and the vehicle speed detector are used. Error calculating means for calculating the mounting error angle of the inertial navigation device to the vehicle from the position, and means for correcting the azimuth angle and the attitude angle from the inertial navigation device using the calculated mounting error angle. And a vehicle position measuring device. 2. Use of an azimuth angle and an attitude angle from an inertial navigation device mounted on a vehicle, and vehicle speed information obtained from a rotation speed of a wheel of the vehicle detected by a vehicle speed detector mounted on the vehicle. Then, in the vehicle position measuring device for measuring the position of the vehicle, the satellite navigation device mounted on the vehicle, the position measured by the satellite navigation device, the inertial navigation device and the vehicle speed detector are used. Error calculating means for calculating the scale factor error of the vehicle speed detector based on the calculated position, and means for correcting the scale factor of the vehicle speed detector with the calculated scale factor error. Vehicle position measuring device. 3. The position data from the satellite navigation device is calculated from the relative position data of the antenna of the satellite navigation device and the wheels of the vehicle, and the azimuth angle and the attitude angle from the inertial navigation device. 3. The vehicle position measuring device according to claim 1, further comprising means for converting the position data into position data, and the converted position is used for calculation by the error calculating means.