JP2016161362A - Wireless coordinate measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure spatial coordinates of a point of interest in a spatial coordinate system with an arbitrary origin using a simple device configuration and method.SOLUTION: A coordinate measurement device measures coordinates of a point of interest by; providing a radio wave transmitter at a point of interest; providing a plurality of receivers positioned at known coordinates to receive the radio wave transmitted by the transmitter; receiving the radio wave transmitted by the transmitter using receiver pairs, each consisting of an arbitrary pair of receivers selected from the plurality of receivers; computing a travel path distance difference, or a difference between a distance from the transmitter to a first receiver and a distance from the transmitter to a second receiver, for one receiver pair; similarly computing a travel path distance difference for each of a plurality of receiver pairs; and computing coordinates of the transmitter from the known coordinates of the plurality of receivers and the travel path distance differences of the receiver pairs.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an apparatus for measuring the coordinates of a target point wirelessly in a coordinate system having an arbitrary point as an origin.

As means for obtaining the three-dimensional coordinates, there are various methods such as optical, ultrasonic, radio, mechanical, magnetic, and GPS (global positioning system). However, each system has advantages and disadvantages, and an inexpensive, easy-to-use and accurate system has not been put into practical use and does not exist as a product.

In the field of basic surveying in the construction industry such as housing, the surveying point is pointed by an indicator (such as a pole) equipped with a reflecting prism, and the reflecting prism is tracked by analyzing the image obtained from the built-in camera. There are products that derive three-dimensional coordinates from distance information obtained by laser measurement and angle information obtained from each built-in two-axis servo motor.

However, this method requires a very high-performance encoder, which increases the cost. In measurement, it is necessary to track the measurement point indicator using the motor as described above, and thus the indicator must be moved within a trackable range, which is inconvenient. In addition, it is impossible to simultaneously measure a plurality of locations by a plurality of people.

Accordingly, the inventor of the present application has made an invention to solve these problems, and has applied for Japanese Patent Application No. 2012-227909 (Japanese Patent Application Laid-Open No. 2014-081232) “Wireless Coordinate Measuring Device”.

JP 2014/081232 A

The technique of Patent Document 1 uses a wireless swept sine wave. The radio itself is less affected by obstacles and is one of the preferred means for performing three-dimensional coordinate measurement, but there is a problem of widening the frequency band used by sweeping the frequency. Coordinate measurement accuracy is greatly affected by the sweep frequency bandwidth, but an arbitrary frequency and bandwidth cannot be selected due to regulations such as the Radio Law.
Therefore, it is necessary to provide a restriction such as operation in an electromagnetically shielded field that is not affected by radio, and versatility is degraded.

Therefore, the present invention has been made to solve the above problems.
The coordinate measuring device according to the present invention is:
“A transmitter that transmits radio waves,
A plurality of receiving units that are arranged at known coordinates in an arbitrary spatial coordinate system and receive radio waves transmitted by the transmitting unit;
Based on the radio wave received by the receiving unit included in the receiving unit pair, a plurality of receiving unit pairs including any two receiving units of the plurality of receiving units, the first of the receiving unit pair from the transmitting unit A propagation path distance difference calculation unit that calculates a propagation path distance difference that is a difference between the distance to the reception unit and the distance from the transmission unit to the second reception unit of the reception unit pair;
A transmission unit coordinate calculation unit that calculates the coordinates of the transmission unit based on the known coordinates of the plurality of reception units and the propagation path distance difference calculated for each of the plurality of reception unit pairs;
With "
It is characterized by that.

In addition, the transmission unit of the coordinate measuring device of the present invention,
“Transmitter is separate from multiple receivers”
It is characterized by that.

Furthermore, the coordinate measuring apparatus of the present invention is
“Radio waves are sine waves of known frequency,
The transmitter unit and the receiver units have local oscillators with different frequencies. ''
It is characterized by that.

According to the present invention, three-dimensional coordinate measurement can be performed using only a single frequency sine wave.

Before the detailed description, common matters in the present specification will be described.
In the present invention, the radio wave transmitted by the transmitter is a radio wave defined by the Japanese Radio Law, and the coordinate means a coordinate in an orthogonal coordinate system in a three-dimensional (three-dimensional) space unless otherwise specified. To do.

It is a figure which shows the concept of this invention. It is a figure which shows the structure of a receiving part. It is a figure which shows the synthesis | combination with the radio wave received by the receiving part pair, and a local oscillation.

FIG. 1 illustrates the basic concept of the present invention.
The reference module is handled so as not to move during a series of coordinate measurements, and can be regarded as the origin (or specific coordinates) of the virtual coordinate system. The reference module has a plurality of receiving units, and in FIG. 1 there are five receiving antennas, but this is not a limitation.
The virtual coordinate system assumes that the horizontal direction is the X axis, the vertical direction is the Y axis, and the depth horizontal direction is the Z axis.
The measurement module includes a measurement point indicating unit that indicates a point whose coordinates are to be measured, a transmission antenna that transmits a radio wave, and a measurement result display unit that displays a result of coordinate measurement. The user moves with this measurement module, points to the point to be coordinate-measured by the measurement point instruction unit, and instructs the measurement module to start measurement by pressing a measurement start switch (not shown). The result of coordinate measurement (in the virtual coordinate system) is displayed on the measurement result display unit.

FIG. 2 shows the structure of the receiving part of the reference module.
First, a radio wave is transmitted from the transmission antenna of the measurement module. In FIG. 2, a 1 GHz sine wave is used as an example, but there is of course no reason limited to this. As is obvious, a 1 GHz local oscillator (not shown) is provided in the measurement module.
The reference module has five receiving units, which are the receiving antennas R1 to R5, respectively.
Each of the reception antennas R1 to R5 receives a radio wave transmitted from the transmission antenna of the measurement module.

The reference module is provided with a clock (local oscillator) of 1.00001 GHz (= 1 GHz + 10 kHz), and each mixer for each 1 GHz sine wave signal received by the receiving antennas R1 to R5 of the sine wave signal generated by the local oscillator. Mix with. Although the line lengths from the local oscillator to the mixer are all different in the figure, the circuits are actually adjusted so that the signals reach all the mixers at the same timing.
A signal mixed by each mixer is read by a microcomputer through an A / D (analog-digital) converter. The microcomputer processes the read signal as data.

FIG. 3 shows a waveform when a sine wave of 1 GHz and a sine wave of 1.00001 GHz (= 1 GHz + 10 kHz) are mixed by a mixer.
When two sine waves having similar frequencies are mixed, a signal whose amplitude varies with a frequency difference as a period (so-called “swell”) is obtained. Since the frequency difference is 10 kHz, the swell frequency is 10 kHz. The aforementioned microcomputer detects the envelope of this amplitude variation and analyzes the waveform.
Hereinafter, based on the above-mentioned prior art document (Japanese Patent Application No. 2012-227909 / Japanese Patent Application Laid-Open No. 2014-081232), common points will be treated only by reference and different points will be mainly described.

The gist of the prior art is to assume four receiving unit pairs, calculate the difference in distance between each of the two receiving units of the receiving unit pair and the transmitting unit, and calculate the transmitting unit with the difference in distance between the four receiving unit pairs. The three-dimensional coordinates are obtained.
In order to configure four receiver units, a method of arranging four receiver units in a triangular pyramid shape was adopted in consideration of cost reduction, but in the present invention, five receiver units are arranged in a quadrangular pyramid shape in order to improve measurement accuracy. It was set as the method to arrange in.
First, as described above, the signal mixed by the mixer has a beat of 10 kHz. By applying FFT (Fast Fourier Transform) processing to the envelope waveform of this signal by a microcomputer, the frequency of the envelope and the mixer The phase difference between the two signals mixed together can be obtained.

At this time, the frequency of the radio wave is f, the speed of light is c, the phase value of the reference signal among the signals mixed in the mixer is θ1, the phase value of the other signal is θn, and the signal of the transmitting antenna and θ1 is received. When the distance between the antennas is d1, and the distance between the transmitting antenna and the antenna that receives the θn signal is dn, the distance difference Dm = dn−d1 can be calculated by the following equation (m = 1 to 4).
The subscripts n and m frequently used in the following formulas are as follows.
n is a number indicating a specific one of a plurality of receiving units (receiving antennas). In the present embodiment, since there are five receiving units, n ranges from 1 to 5.
Of these, the receiving unit of n = 1 is mainly treated, and a receiving unit pair is configured by a combination with receiving units other than n = 1 (n = 2 to 5). In other words, when the receiving unit is expressed as Rn, there are four receiving unit pairs: “R1 pair R2”, “R1 pair R3”, “R1 pair R4”, and “R1 pair R5”. These four combinations of receiver pairs are denoted by m. For example, “R1 vs. R2” is m = 1. When there are five receiving units, m is in the range of 1-4. When written differently using m, it also means that the receiving unit pair “R1 vs. R (m + 1)” is shown.

From this, if the frequency f of the radio wave and the frequency of the local oscillator in the reference module (= determining the swell frequency when mixed by the mixer) are known, “one of the pair of the transmitting antenna and the receiving unit is determined. The difference D between the “distance from the receiving unit” and the “distance between the transmitting antenna and the other receiving unit of the receiving unit pair” is known.
Since the same can be said for the relationship with the signals of the other receiving units, the difference in distance between the receiving antennas R1 to R5 with respect to the transmitting antenna is obtained in the same way.

In the prior art, four receiving units are configured by four receiving units. However, in the present invention, four receiving unit pairs are configured by five receiving units, and therefore, a part corresponding to Equation 4 in the prior art document. Is as follows.

Based on the contents so far, a method for obtaining the coordinates of the transmitting antenna from the distance difference Dm will be described.
Let the coordinates of the transmitting antenna l be l (x, y, z).
The coordinates of the receiving antennas R1 to R5 are known and are set to Rn (x, y, z) (n = 1 to 5).
Let dn be the linear distance between the receiving antenna Rn and the transmitting antenna l (n = 1 to 5).
The difference (distance difference) between d1 and d2 to d4 is rm (m = 1 to 4).
Am (m = 1 to 4) is obtained by converting a known delay factor on the circuit generated between the receiving antennas R1 and Rn into a distance.
A phase value obtained by subjecting the mixer output waveform to A / D conversion and FFT is θn (n = 1 to 5).

At this time,
T1 = D1-A1
T2 = D2-A2
T3 = D3-A3
T4 = D4-A4
Then,
C, X, Y, and Z can be defined as intermediate variables as follows.

Based on the above-mentioned intermediate variables, the coordinates l (x, y, z) of the transmitting antenna are obtained by the following equations.

In this way, the coordinates of the transmitting antenna are obtained by substituting the known coordinates of the five receiving units and the propagation path distance difference measured in each pair of receiving units configured by each receiving unit into the mathematical formula. Is possible.

In the measurement module of FIG. 1, the part where the transmission antenna is present is the target of the three-dimensional coordinate measurement. Since the distance from the antenna to the measurement point instruction unit is known, the coordinates of the measurement point instruction unit can also be calculated.

Further, although the measurement is performed on the reference module side, the measurement result may be notified to the measurement module side by communication means. In the example shown in FIG. 2, the result of measurement using Bluetooth (registered trademark) is transmitted to the measurement module.

The present invention has been described with reference to preferred embodiments. However, the present invention is not limited to these embodiments, and many modifications can be made without departing from the spirit of the invention. Of course.

Coordinate measurement at a specific location can be easily performed using a transmitter and a receiver that can be mass-produced, and it has the effect of improving the efficiency of operations such as dimension measurement and surveying.

Claims (3)

A transmitter for transmitting radio waves;
A plurality of receiving units arranged at known coordinates in an arbitrary spatial coordinate system and receiving radio waves transmitted by the transmitting unit;
A plurality of receiving unit pairs each including any two receiving units of the plurality of receiving units, and based on a radio wave received by the receiving unit included in the receiving unit pair, the transmitting unit to the receiving unit pair; A propagation path distance difference calculation unit for calculating a propagation path distance difference that is a difference between the distance from the first reception unit and the distance from the transmission unit to the second reception unit of the reception unit pair;
A transmitter coordinate calculator that calculates the coordinates of the transmitter based on the known coordinates of the plurality of receivers and the propagation path distance difference calculated for each of the plurality of receiver pairs;
A coordinate measuring apparatus comprising: The coordinate measuring apparatus according to claim 1, wherein the transmitting unit is provided separately from the plurality of receiving units. The radio wave is a sine wave having a known frequency, and includes local oscillators having different frequencies on the transmitter side and the plurality of receiver sides, respectively. Coordinate measuring device.