JP2002022816A - Deviation measuring apparatus and deviation speed measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute a deviation measuring apparatus and a deviation speed measuring apparatus wherein the problem of a drift by an acceleration sensor is solved, a reference station is not required and the deviation amount or the deviation speed of a moving body can be measured with high accuracy. SOLUTION: The change amount of the carrier frequency of radio waves received from a satellite for positioning is observed in every prescribed observation cycle. The movement of the satellite in the observation cycle and the drift position of the carrier frequency of the satellite are subtracted. The change amount of the carrier phase due to the movement of a receiving point is found. Regarding four or more satellites, deviation amounts of their receiving points are found on the basis of change amounts of carrier phases due to movements of the receiving points, they are integrated, and the integrated deviation amount of the receiving points is found. The deviation speed is found on the basis of the deviation amount per unit time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for receiving a radio wave transmitted from a positioning satellite such as a GPS satellite on a mobile body.
The present invention relates to a device for measuring a displacement amount or a displacement speed of a moving body.

[0002]

2. Description of the Related Art Conventionally, in a ship, for example, which measures the depth of the seabed or the seafloor topography with a sounding device, the change in the vertical direction of the ship is measured in order to perform the measurement without being affected by the vertical movement of the ship. Heave gauge is used. The heave meter is provided with an acceleration sensor for detecting a vertical acceleration.

[0003]

However, as in a conventional heave meter, the displacement of a moving body is measured by double integrating the output signal of an acceleration sensor for detecting acceleration.
An expensive and high-accuracy acceleration sensor is required, and the measurement error of the amount of displacement of the moving object largely depends on the accuracy of the acceleration sensor. In addition, since errors accumulate due to integration, it has been difficult to measure the displacement of a moving body that oscillates in a long cycle with high accuracy.

Therefore, it is conceivable to use GPS without using such an acceleration sensor. For example, if the height of the receiving point is obtained by an RTK (real-time kinematic positioning) method for performing relative positioning of the carrier phase, this can be used instead of the heave meter.

However, in order to perform measurement by the RTK method using GPS, it is necessary to provide a reference station on land, and its service area is also about 20 km from the reference station, and measurement at a point further away from the land is not possible. Can not. Note that G
With the PS code differential system, the service area is widened, but high positioning accuracy cannot be obtained.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the problem of drift caused by an acceleration sensor, eliminate the need for a reference station, and measure the displacement or displacement speed of a moving object with high accuracy. It is to provide a position velocity measuring device.

[0007]

A displacement measuring apparatus according to the present invention receives a radio wave transmitted from a positioning satellite such as a GPS satellite and superimposed on the radio wave, for example, a C / A code or the like. And a means for observing the carrier phase change amount DR of the radio wave in the observation cycle from the previous observation to the current observation. Further, the carrier phase change DRa due to the movement of the positioning satellite with respect to the position of the measured receiving point and the carrier phase change DRb due to the drift of the carrier frequency of the radio wave transmitted from the positioning satellite in the above-described observation cycle are calculated as described above. The means for obtaining the change amount DR ′ of the carrier phase due to the movement of the reception point by subtracting the change amount DR ′ of the carrier phase due to the observation, and the change amount DR ′ of the carrier phase obtained for four or more positioning satellites, Means for determining the amount of deviation of the receiving point in the observation period;
Means for integrating the amount of deviation of the receiving point in the observation period to obtain an integrated amount of deviation of the receiving point.

Further, the displacement velocity measuring device of the present invention is provided with a means for obtaining the displacement of the receiving point per unit time, that is, the displacement velocity of the moving body, from the displacement of the receiving point in the observation period.

As described above, the amount of change in the distance from the receiving point to each satellite is determined by using the amount of change in the carrier phase of the radio wave transmitted from each positioning satellite. Based on the direction cosine of the satellite,
The displacement amount and the displacement speed in the dimensional direction are measured.

According to the present invention, since a conventional acceleration sensor is not required, the size and cost can be reduced. Also,
A large accumulated error does not occur, and high-precision measurement can be performed. Further, since no base station is required, the whole system does not become large and the service area is not restricted.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of a displacement measuring device and displacement speed measuring device for a moving object according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing the configuration of the entire apparatus. In FIG. 1, reference numeral 1 denotes a GPS antenna, and 2 denotes a signal from the GPS antenna 1 as an intermediate frequency signal I.
The down-converter 3 for converting the signal into F is a received signal processing section for processing the intermediate frequency signal to obtain information on the C / A code phase and the carrier phase. Reference numeral 4 denotes a positioning operation unit that obtains a deviation amount and a deviation speed of a reception point based on information obtained under the control of the reception signal processing unit 3.

The down-converter 2 performs frequency conversion by mixing a reference oscillator 21 for generating a reference frequency signal with the reference frequency signal, and further converts the data into digital data of a predetermined number of bits. And a circuit 22 including a D converter and the like.

The received signal processing section 3 multiplies a C / A code generator, a code NCO for numerically controlling the code phase thereof, three C / A codes having a predetermined code phase shift, and an input signal, and Is provided with a correlator that obtains a correlation by integrating each of the values. The positioning operation processing unit 4 obtains a C / A code phase from these correlation results, and performs tracking thereof. Also, the reception signal processing unit 3
Includes a carrier NCO that generates carrier signals having phases of 0 ° and 90 °, and a correlator that multiplies the carrier signal by an input signal and integrates the respective results to obtain a correlation. In addition, the received signal processing unit 3 includes a phase counter that accumulates and counts the correction amount (tracking amount) of the carrier phase of the input signal, thereby obtaining the carrier phase and tracking the same.

The positioning operation unit 4 includes a CPU 41, a ROM 4
2, RAM43, RTC (real-time clock) 4
4. Interface 4 for outputting data to outside
5 and an interface 46 for inputting and outputting data to and from the received signal processing unit 3. The positioning calculation unit 4 controls the phase of the code NCO based on the correlation value regarding the code phase obtained by the reception signal processing unit 3 and controls the frequency of the carrier NCO based on the correlation value regarding the carrier phase. Tracking of phase and carrier phase is performed. Further, the integrated count value of the carrier phase is read, and a change in the wave number (carrier phase change amount DR) including the phase angle corresponding to the fraction of the wavelength in the observation period is obtained.

As will be described later, a three-dimensional displacement amount and a displacement speed of a receiving point (the center of the GPS antenna 1) are calculated and output to the outside.

FIG. 2 is a flowchart showing a processing procedure of the positioning operation unit 4. First, single positioning is performed based on the code phases of a plurality of currently tracking satellites (n1). The position of the receiving point obtained by the sole positioning is used to obtain the direction cosine from the receiving point to each satellite. Next, the reception signal processing unit 3
The integrated count value of the correction amount (tracking amount) of the carrier phase obtained by the above is read, and the difference from the previous value is obtained as the carrier phase change amount DR (n2 → n3). Subsequently, a change DRa in the carrier phase caused by the movement of the satellite in the observation cycle from the previous observation to the current observation is calculated (n4). Specifically, the position of the receiving point, the position of the satellite at the time of the previous observation, and the position of the satellite at the time of the current observation are calculated backward. In addition, the carrier phase change DRb due to the drift of the reference oscillator included in each satellite is determined by the GP in the navigation message.
It is calculated from the S time correction coefficient (n5). Then, the carrier phase change DRa due to the movement of the receiving point is subtracted from the carrier phase change DRa due to the satellite movement and the carrier phase change DRb due to the drift of the reference oscillator of the satellite from the carrier phase change DR. (N6).

Thereafter, from the DR 'obtained for each of the four or more satellites and the current position of each satellite, a change in the distance from the receiving point to each satellite is obtained. An equation is established from the direction cosine and the deviation amount of the receiving point in the three-dimensional direction is obtained. That is, it is determined by the product of the inverse matrix of the direction cosine and the matrix of the distance change amount between the receiving point and the satellite. At this time, the fourth unknown is obtained as the drift of the reference oscillator of the receiver (n7). Since the amount of deviation of the receiving point is the amount of deviation from the time of the previous observation to the time of the current observation, the accumulated amount of deviation is obtained by integrating this amount of deviation with the accumulated value so far. This is output (n8). Also, from the amount of deviation of the receiving point during the observation period,
The displacement amount per second is obtained, and this is output as the displacement speed per second (n9).

Thereafter, the flow returns to the process of step n1, and the above process is repeated for each predetermined observation cycle. For example, 0.
By repeating every two seconds, the integrated deviation amount and deviation speed of the receiving point are obtained in a period of 0.2 seconds.

According to this embodiment, the amount of deviation of the receiving point is obtained from the amount of change in the carrier phase, and the amount of deviation is integrated with the amount of deviation independently of the result of the single positioning. Since it is determined sequentially, the accumulated error can be kept small when the receiving point reciprocates around a certain average position.

For example, when observing the vertical movement of a ship due to waves, a heave meter using a conventional acceleration sensor requires 20 meters.
Approximately 30% of the position error occurs per second, which is not suitable for detecting a long-period change exceeding 20 seconds. On the other hand, according to the present invention, for example, even if integration is continued for about one minute,
A positioning accuracy of about ± 5 cm can be obtained. That is, a long-period vertical movement of about 1 minute can be observed.

Further, the conventional one using an acceleration sensor is expensive at several million yen. However, according to the present invention, only the GPS receiver and the positioning calculation unit are required. It can be configured for around 10,000 yen.

The invention of the present application can also measure the rolling of a ship in a similar manner besides the heave meter. Further, in general, the present invention can be similarly applied to, for example, measuring the motion of the upper end of a pole-shaped member having a fixed lower end, the motion of a pendulum-shaped member, the motion of a member that swings in a seesaw shape, and the like. It works.

[0023]

According to the present invention, since no acceleration sensor is required, a large accumulated error does not occur and high-precision measurement can be performed. Further, since the reference station is not required, the whole system does not become large and the service area is not restricted.

Further, since the accuracy of measuring the amount of deviation at each observation can be improved, the accumulated error caused by integrating the amount of deviation can be suppressed. In particular, when the receiving point reciprocates, the accumulated error is totally canceled,
Long-period motion can be measured with high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a displacement measuring device and a displacement speed measuring device.

FIG. 2 is a flowchart showing a processing procedure in a positioning calculation unit of the apparatus.

[Explanation of symbols]

 1-GPS antenna

Claims (2)

[Claims] 1. A positioning means for receiving a radio wave transmitted from a positioning satellite and obtaining a position of a receiving point from a phase of a code superimposed on the radio wave, Means for observing the carrier phase change amount DR of the radio wave in the observation cycle, and calculating the carrier phase change DRa in the observation cycle due to movement of the positioning satellite with respect to the position of the reception point obtained by the positioning means. The carrier phase change DRa due to the carrier phase drift DRb and the carrier phase change DRb due to the drift of the carrier frequency of the radio wave are subtracted from the carrier phase change DR due to the observation to obtain the carrier phase change DR ′ accompanying the movement of the reception point. From the carrier phase change amount DR 'obtained for four or more positioning satellites in the observation period. A deviation measuring device comprising: means for calculating a deviation amount of a trust point; and means for integrating a deviation amount of a reception point in the observation period to obtain an integrated deviation amount. 2. The method according to claim 1, further comprising the step of integrating the amount of deviation of the receiving point to obtain an integrated amount of deviation, and calculating the number of receiving points per unit time from the amount of deviation of the receiving point in the observation cycle. A displacement speed measuring device provided with a means for calculating a displacement amount.