JP3084533B2 - Azimuth angle measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an azimuth angle measuring device for detecting an azimuth angle, a position, a speed and the like of a navigating body such as a ship or a car.

[0002]

2. Description of the Related Art In recent years, as a system for constantly detecting the position of a navigating body such as a ship, a GP using satellite radio waves has been used.
S (Global Positioning System)
em) Navigation has been proposed. This is to always measure the position of the navigator three-dimensionally based on data from three or more satellites, and the launch of the satellite is completed in 1990.
In the age, it is expected to be operated using C / A code which is a private code. However, above
In the GPS signal processing by the normal measurement of the above, it was only possible to measure the position of the navigating body, and it was not possible to measure the azimuth due to a large position measurement error. On the other hand, there has been disclosed a method of calculating the azimuth of a navigation body by a two-position difference high-accuracy simultaneous measurement method for measuring the phase difference of satellite radio waves, which has been used in surveying called differential GPS.

The principle of measurement will be described below with reference to FIG. In FIG. 4, reference numerals 1 and 2 denote reception antennas attached to a navigation body (not shown) such as a ship, for example, and the distance L between the antennas 1 and 2, which is the base line length, is assumed to be known. . The radio waves from the antennas 1 and 2 are supplied to the GPS azimuth calculation unit 3 and calculate the azimuth component ψ of the navigation body by the calculation described below. Now, consider a case where radio waves from one satellite 7 are received simultaneously by antennas 1 and 2 as shown in FIG. At this time, due to the position L of the satellite 7 and the distance L between the antennas 1 and 2, there is a distance difference D between the radio wave received by the antenna 1 and the radio wave received by the antenna 2 in FIG. . This distance difference D can be measured as a phase difference (time difference) by focusing on a specific radio wave of a carrier wave. Therefore, by multiplying the phase difference by the wavelength of the radio wave, the distance difference D can be obtained. it can. If D is found, then L is known,

[0004]

Ψ = cos ^-1 (D / L)

[0005] As a result, the base line length L with respect to the observation satellite 7, that is, the azimuth component ψ of the navigation body can be obtained. In this measurement, it is not always necessary to demodulate the received code.

On the other hand, the azimuth θ between the line connecting the satellite 7 and the receiving antennas 1 and 2 and the true north N can be obtained as follows. That is, after receiving the radio wave from the satellite 7 with the antenna 1, the radio wave of at least two other satellites (not shown) is received. And C of these received radio waves
By demodulating the / A code and knowing the transmission time and reception time of the radio wave transmitted from the satellite, the propagation time of the radio wave from the satellite is obtained, and then multiplied by the wavelength of the radio wave,
The distance from the satellite to the antenna 1 and hence to the vehicle is determined. The position equidistant from one satellite is on a sphere whose radius is the distance.
The position of the receiving antenna 1 can be determined by determining the number of spherical surfaces and the intersection thereof. If the position of the antenna 1 is obtained, the position of the satellite 7 is known, and therefore, the azimuth angle θ can be obtained from the direction cosine of the position vector between the antenna 1 and the satellite 7.

An element for executing a process of calculating a position from reception of a radio wave for obtaining the position of the antenna 1 is a GPS position calculation unit 4 which receives a radio wave from the antenna 1.
The element for performing the above-described calculation of 演算 and the calculation of (ψ + θ) based on the position data and the reception data from the antennas 1 and 2 is the GPS azimuth calculation unit 3. In this way, the base line length L calculated by the GPS azimuth calculation unit 3, and hence the azimuth of the navigation body, becomes (θ + ψ), which is output as a digital signal.

[0008]

However, in the above-described azimuth angle measuring apparatus using the GPS phase difference, it takes too much calculation time to solve the ambiguity of the phase for azimuth angle measurement. However, there is a problem that the azimuth cannot be measured. For this reason, it has not been possible to connect to a device that requires azimuth data at high speed. In view of the above, an object of the present invention is to enable high-speed connection to a device that requires azimuth data.

[0009]

The azimuth angle measuring device of the present invention is, for example, as shown in FIG. 1, two or more satellite receiving antennas 1, 2 to be installed at a predetermined distance on a navigation body, and A calculating means 3 for calculating an azimuth angle based on a phase difference between satellite radio waves received by the antennas 1 and 2, and an output of the calculating means 3 as an input, and an azimuth angle estimating calculation is performed using a value of a past calculated output. An estimation operation unit 5 is provided.
Is an azimuth output.

[0010]

The present invention, according to the azimuth measuring device, the azimuth angle output interval, it is possible to Ku out force regardless of the reception interval of the satellite receiving radio waves, it is possible to continuously measure the azimuth, azimuth data at high speed can be contact communication to other devices requiring.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an azimuth angle measuring device according to the present invention will be described below in detail with reference to FIGS. In FIG. 1, parts corresponding to those in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 2 shows a time chart from reception of a radio wave from a GPS satellite to output of an azimuth angle. FIG. 2A shows a signal obtained by receiving the phase of the radio wave of the GPS satellite, and it is assumed that the time is the rising of a high level (hereinafter referred to as H-level). Based on this time, FIG. 2B shows that the time T ₁ for solving the phase ambiguity in the GPS azimuth calculation unit 3 and calculating the azimuth angle based on the output from the position calculation unit 4 is H−.
Expressed by level. Further, FIG. 2c is a time chart for outputting the aforementioned azimuth angle output is delayed by a time T ₂ from the reception reference time. It is assumed that the reception interval of the satellite radio wave is τ. At this time, the output value of the azimuth angle is measured as the delayed value by T _2. Satellite signal reception interval τ
Is extremely small, there is no problem with the output delay, but the actual azimuth calculation requires a calculation time of, for example, 500 msec. Therefore, for example, when the navigating body is 10
When turning at an angular velocity of ° / s, an azimuth error of 5 ° occurs.

In this example, as shown in FIG.
Using the output of the arithmetic unit 3, the azimuth output time interval is as follows:
An estimated azimuth calculation unit 5 for estimating the inside is provided. This
The estimated azimuth calculation unit 5 will be described with reference to FIG. GPS method
The output azimuth angle φ of the position calculation unit is output at the reception interval τ.
And the current time is t_x, Azimuth angle φ_xAnd this time
Reception time t before_nThe azimuth at φ_n, The previous one
The reception time and azimuth at the signal interval are t_n-1, Φ_n-1Toss
You. At this time, t_XAzimuth φ at_xIs φ_n-1, Φ _nFor
Stay

[0013]

(Equation 2)

It is estimated that The element that performs this calculation is the estimated azimuth calculation unit 5 shown in FIG. This output is displayed on the display 6 together with the position output from the position calculation unit. Note that in Equation 2,

[0015]

(Equation 3)

GDOP indicating the reception status of the satellite
(Geometric Dilution Of Pr
definition of the coefficients α and β as a function of
If the DOP is large and the phase error is considered to be large, the values of α and β may be reduced, and if the GDOP is small, the function may be set so that α ≒ 1 and β ≒ 1.

In this embodiment, the number of antennas is two, but by adding one more so that the base line length is perpendicular to the two antennas, in addition to the azimuth,
The roll angle and the pitch angle can be measured. Even in such a system, continuous roll angle and pitch angle outputs can be obtained by providing a roll angle and pitch angle estimation calculation unit as in the case of the azimuth angle. It should be noted that the present invention is not limited to the above-described embodiment, but can adopt various other configurations without departing from the gist of the present invention.

[0018]

As described above, according to the present invention, it is possible to continuously measure the azimuth of a navigating body such as a ship, and to obtain high-speed azimuth data from an autopilot or a collision prevention device. There is an advantage that it can be connected to equipment that requires.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of an azimuth angle measuring device of the present invention.

FIG. 2 is a diagram for describing the present invention.

FIG. 3 is a diagram for explanation of the present invention.

FIG. 4 is a configuration diagram for explaining a principle of measuring an azimuth angle;

[Explanation of symbols]

 1, 2 receiving antenna 3 azimuth calculation unit 4 position calculation unit 5 estimated azimuth calculation unit 6 display

Continued on the front page (72) Inventor Noriyuki Akabane 2-16-46 Minami Kamata, Ota-ku, Tokyo Inside Tokimec Co., Ltd. (72) Inventor Atsushi Kawakami 2-16-46 Minami Kamata, Ota-ku, Tokyo Co., Ltd. In Tokimec (56) References JP-A-60-244878 (JP, A) JP-A-63-29279 (JP, A) JP-A-55-117977 (JP, A) JP-A-59-88666 (JP, A) JP-A-60-188810 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01C 21/00-21/24 G01S 5/14 B60R 11/02

Claims (2)

(57) [Claims] An azimuth having two or more satellite receiving antennas to be installed at a predetermined distance from a navigation body, and arithmetic means for calculating an azimuth based on a phase difference between satellite radio waves received by the antennas. In the measuring device, an estimation calculation unit is provided for inputting the output of the calculation unit as an input, correcting a time delay of the output by using a value of the past calculation output, and outputting the output at an arbitrary time, and outputting the output of the estimation calculation unit to an azimuth angle. An azimuth angle measuring device characterized in that it is configured to be an output. 2. An arithmetic unit for providing three or more antennas and outputting a roll angle or a pitch angle other than an azimuth angle,
An estimation operation unit for inputting the output of the operation unit as an input, correcting the time delay of the output using the value of the operation output in the past, and providing an arbitrary time output, and outputting the output of the estimation operation unit as a roll angle or a pitch angle output The azimuth angle measuring device according to claim 1, wherein the azimuth angle measuring device is configured to be as follows.