JP2008039562A - Method and device for detecting position of mobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To safely and precisely detect the position of a mobile by clearly distinguishing a region of which the mobile has already completed inspection from a non-inspected region. <P>SOLUTION: A position detection device includes: a transmission coil 5 for transmitting magnetism provided at the mobile A; the reference tool 6, where a plurality of reception coils 61, 62 for receiving magnetism transmitted from the transmission coil 5 are arranged discretely in the same plane shape; and a computing means for computing the distance from respective reception coils 61, 62 to the transmission coil 5 based on magnetic information received by the reception coils 61, 62, and determining and outputting the coordinates position of the transmission coil 5 based on each obtained distance information. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a position detection method and apparatus for a moving body.

  A position detection system for a moving object such as a person or a vehicle is composed of a plurality of wireless LAN systems. A method of detecting the position of a terminal by performing triangulation using arrival times or arrival time differences of radio signals reaching a plurality of wireless LAN terminals from a wireless LAN terminal is known (Patent Document 1).

Further, as a position detection means for a moving body that does not depend on radio, a travel meter such as a motor encoder or a gyroscope is known in the field of autonomous traveling robots, automatic guided vehicles, and the like (Patent Document 2).
JP 2005-274364 A Japanese Patent Laid-Open No. 8-21936

  In the field of non-destructive inspection in which buried objects are detected and steel frames on the walls of buildings and floors are investigated, it is necessary to inspect a moving body equipped with a detection sensor while moving in order to cover all areas to be inspected. Moving to an uninspected area may involve the risk of the inspector, and the equipment used to reduce the inspector's mental and physical stress must be thin and light, and wood, earth and concrete -There is a need to make it less susceptible to substances that disturb inspection accuracy, such as moisture.

  An object of the present invention is to solve such a conventional problem, and it is possible to clearly distinguish the area where the moving body has already been inspected from the uninspected area, and to move the moving body safely and accurately. It is an object of the present invention to provide a position detection method and a detection apparatus for a moving body that can detect the position of the moving body.

  A moving body position detection method that realizes the object of the present invention is to receive a magnetic signal transmitted from a transmitting coil on a moving body side by a plurality of receiving coils that are spaced apart from a reference device, and to receive the magnetic flux received by each receiving coil. The position of the moving body is specified by distance information based on density.

  A first configuration of a moving body position detecting device that realizes the object of the present invention is such that a transmitting coil that transmits magnetism provided on a moving body and a plurality of receiving coils that receive magnetism transmitted by the transmitting coil are coplanar. The distance from each receiving coil to the transmitting coil is calculated on the basis of magnetic information received by the plurality of receiving coils and the reference tool spaced apart in the shape, and the coordinates of the transmitting coil based on the obtained distance information And calculating means for determining and outputting the position.

  A second configuration of the position detection apparatus for a moving body that realizes the object of the present invention is characterized in that the transmission coil is formed of a printed board.

  In the above-described invention, first, in order to avoid a risk associated with movement to an uninspected area, in order to identify an inspection area or a safe area, a plurality of receiving coils are used as a reference tool which is a rod-shaped device. It is possible to use the reference tool as a boundary between the inspected area that is safe and the uninspected area that is dangerous.

  Second, pay attention to magnetism that is not easily affected by substances other than metal, and a plurality of receiving coils are arranged in the reference tool and placed in the inspection area.

  Third, a light transmitting coil is placed on the moving body, and the magnetic field irradiated by the transmitting coil is received by the reference tool by scanning so as not to contact the inspection area, and the receiving coil built in the reference tool The position of the moving body can be specified by calculating the triangulation by converting the intensities of the plurality of signals detected in step 1 into a distance from a reference table prepared in advance.

  According to the present invention, the position detection method using magnetism is less affected by non-metallic materials such as wood, soil, concrete, moisture, water surface, etc., and can be realized thinly and lightly.

  In addition, it is easy for the inspector to visually determine the distinction between the examination execution area or the safety area and the non-inspection area with the reference tool, and an effect of reducing mental and physical stress can be obtained.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings.

  1 to 4 show an embodiment of a moving body position detection system according to the present invention. FIG. 1 is a block diagram showing a schematic configuration of the entire system, FIG. 2 shows a reference table for converting a signal received by the receiving coil in FIG. 1 into a distance and a supplementary diagram thereof, and FIG. 3 shows signal processing of the system It is a flowchart to explain.

  In FIG. 1, the controller 1 transmits a control signal so that the D / A converter 2 generates a 1 kHz sine wave. The D / A converter 2 receives a control signal from the controller 1 and transmits a sine wave electric signal to the amplifier 3. The amplifier 3 receives the sine wave electric signal from the D / A converter 2 and amplifies it, and then suppresses the high-frequency component by the LPF 4 and is provided in the moving body A that is hand-held by the operator via the transmission cable 21. The amplified sinusoidal electric signal is transmitted to the transmission coil 5.

  The transmission coil 5 receives an amplified sine wave electrical signal from the LPF 4, so that a current flows and generates an AC magnetic field omnidirectionally in a horizontal plane.

  The reference tool 6 has a configuration in which two receiving coils 61 and 62 are built in a cylindrical body 63 formed in a cylindrical shape having a length of, for example, about 80 cm and having a constant interval, and is transmitted from the transmitting coil 5. The AC magnetic field received by the two receiving coils 61 and 62 incorporated in the cylinder 63 is received.

  The two receiving coils 61 and 62 transmit the received signals converted into voltage values to the amplifiers 7 and 8 after converting the received magnetic field into electric signals. The amplifiers 7 and 8 amplify the sine wave electrical signals received from the receiving coils 61 and 62 of the reference tool 6 and transmit them to the LPFs 9 and 10.

  The LPF 9 and the LPF 10 transmit received signals to the A / D converters 11 and 12 after suppressing high frequency components (noise) of the sine wave electrical signals received from the amplifiers 7 and 8.

  The A / D converters 11 and 12 receive sine wave electrical signals from the LPFs 9 and 10, capture the electrical signals at a sampling interval of 16 kHz, convert them from analog signal values to digital signal values, and send them to the controller 1. Send data.

  The flow up to this point is indicated by step (hereinafter referred to as S) 1 in the flowchart of FIG.

  For signals A / D converted by the A / D converters 11 and 12, the controller 1 uses 16 points per wave as data points and stores data for 8 waves (data amount: 16 points × 8 waves) in an internal memory ( (Not shown) and these are subjected to quadrature detection calculation (S2). The equation for the quadrature detection calculation is expressed as Equation (1) and Equation (2), where T is the period of the sine wave.

  Here, T indicates the period of the sine wave. The controller 1 transmits the data subjected to the quadrature detection calculation to the calculator 13. The computing unit 13 receives the data transmitted from the controller 1 and performs a square-square process shown in Expression (3) (S3).

  The computing unit 13 uses a reference table (described in FIG. 2) for converting signals received by the receiving coils 61 and 62 into distances, and a distance r1 from the center of the receiving coils 61 and 62 to the center of the transmitting coil 5. And r2 are calculated (S4).

  The center position (xo, yo) of the transmission coil 5 from the distances r1 and r2 is as follows when the distance (base line length) between the reception coils 51 and 52 is d and the center of the reception coil 61 is the coordinate origin: It is calculated (S5).

  The calculating part 13 transmits the data calculated by Formula (4) and Formula (5) to the display 15 (S6).

  The display 14 displays the coordinates of the data received from the calculator 13 as shown in FIG. 4 to be described later, and transmits the position information of the moving body to the operator of the moving body A.

  With reference to FIG. In FIG. 2, the horizontal axis represents the magnetic flux density Bs (unit T “Tesla”) when the receiving coils 61 and 62 receive the magnetism transmitted from the transmitting coil 5 in the air, and the vertical axis represents the distance r (cm). . In FIG. 2, the characteristic line indicating the relationship between the magnetic flux density and the distance shows a downward trend, and the distance r decreases as the magnetic flux density Bs increases. This characteristic is obtained by the following calculation formula when the transmission coil 5 is a rectangular ABCD and the position of the reception coil 61 (or 62) is a point P.

  In FIG. 2, the magnetic field H in the case where the current I flows through the AB line segment L of the transmission coil 5 has an angle formed by PA and the line segment L as θ1, PB, and line as shown in FIG. When the angle formed by the minute L is θ2, it is obtained as shown in Equation (6).

Here, when the coordinates of the point P are (x, y) = (xo, yo), the magnetic field H _AB that the point P receives from the line segment L _AB is obtained as shown in Expression (7).

Similarly, the equation (8) is similarly obtained for the magnetic field HBC from the line segment BC.

Similarly, the equation (9) is similarly obtained for the magnetic field HCD from the line segment CD.

Similarly, the magnetic field HDA from the line segment DA is similarly obtained by the equation (10).

Thus, the magnetic field HP at the observation point P (xo, yo) is expressed by the equation (11).

Therefore, the calculated magnetic flux density BP is expressed by Expression (12).

Where μo is the relative permeability of vacuum (4π × 10 ⁻⁷ ), and t is the number of turns of the transmission coil.

  This calculation is also for determining the dimensions and the number of turns of the coil with respect to the measurement range by design. In this embodiment, the range within which the operator can reach the measurement range is (x, y) = (− 100 mm to 1100 mm). , 0 mm to 400 mm), and the settings are as shown in Table 1.

The setting of Table 1 is based on the setting value of the receiving coil shown in Table 2 and the setting value of the system of this embodiment shown in Table 3, and the thermal noise BN calculated from Expression (13) is 3.3 × 10 ⁻¹² ( T), and the intensity of the magnetic flux density BP from the transmission coil calculated by the equation (12) is sufficiently large (FIG. 2A), and a sufficient signal-to-noise ratio S / N (= BS / BN) is ensured. It has come to be.

Here, k is the Boltzmann constant (= 1.38 × 10 ⁻²³ (J / K)), B is the bandwidth of the receiver (= 10 kHz), and T is the temperature (= 300 K).

  The reference table shown in FIG. 2A has a conversion error due to manufacturing accuracy and the shape of the transmission coil 5. Therefore, in the present invention, the conversion correction coefficient α is provided, and the calculation unit 12 matches the calculated value BS and the actually measured value VP according to the conversion formula shown by the formula (14), and the reference table is used flexibly.

  Further, the strength of the magnetic flux density BP and the actually measured value VP sequentially change depending on the positional relationship between the transmission coil and the reception coil. In order to replace the distances r1 and r2, a method using an approximation function and a method using an interpolation function can be mentioned. In this embodiment, a method using an interpolation function is adopted in consideration of the ease of system adjustment.

  The coordinate position of the transmission coil 5 is obtained by the above-described method, and the data is displayed on the display 14.

  In this embodiment, the operator arranges the reference tool 6 in front of him so that the receiving coil 61 is on the left side and the receiving coil 62 is on the right side. Then, holding the moving body A in the hand, the moving body A is moved in the left-right direction from the front side, and when one scan corresponding to the length of the reference tool 6 is completed, the moving body A is shifted forward by a predetermined length. Now move from right to left. Such an operation is repeated until, for example, the operator's hand is fully extended.

  FIG. 4 shows the movement trajectory when the above-mentioned operator scans the moving object A in a zigzag shape. The trajectory indicated by the solid line is the actual movement trajectory (course), and the trajectory indicated by the * mark is the data received by the receiving coil. The calculated position is shown.

  In order to confirm the effectiveness of the present invention, a reference tool 6 (FIG. 1) is installed at a ground altitude of 30 mm on a flat sand ground assuming detection of a buried object, and a transmission coil 5 (FIG. 1) at a ground altitude of 5 cm in front of it. 1) was installed.

  Then, the moving body A is moved left and right (scanning direction) and back and forth (traveling direction) while the ground altitude of the transmission coil 5 is kept constant, and the position of the moving body (in this experiment, the transmission coil 5) is obtained by calculation. A test was conducted.

  In the figure, the horizontal axis represents the scanning direction x (mm), and the vertical axis represents the traveling direction y (mm). The solid line in the figure is a test course when moving the transmission coil, and the data indicated by * indicates the detected position. The detected position follows the test course well, and the positional accuracy is within 3 cm. In the field of non-destructive inspection for investigating buried objects, building walls and floor steel frames, etc., it is considered that an error of 3 cm or less is allowed, and the present invention enables inspection while moving the entire inspection area.

  In addition, the transmission coil is made of a multilayer printed board, so that it is thin and light (about 300 g in this embodiment), reduces the mental and physical stress of the scanner, and makes the scanner safe. Since it can proceed with the reference tool as a boundary while checking, the danger associated with the uninspected area can be avoided.

  Furthermore, the use of magnetism as the transmission medium between the transmission coil 5 (FIG. 1) and the reception coils 61 and 62 (FIG. 1) makes it less susceptible to influences other than metals such as wood, earth, concrete and moisture. ing.

System diagram. The reference table for converting the signal received with the receiving coil into distance, and its supplementary figure. The flowchart explaining the signal processing of a system. Diagram showing the detection position for the test course

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Controller 2 ... D / A converter 3, 7, 8 ... Amplifier 4, 9, 10 ... Low pass filter (LPF)
5 ... Transmitting coil 6 ... Reference tool 61, 62 ... Receiving coil 11, 12 ... A / D converter 13 ... Calculator 14 ... Display

Claims (3)

  Receiving magnetic signals transmitted from the transmitting coil on the moving body by a plurality of receiving coils arranged apart from the reference tool, and specifying the position of the moving body based on distance information based on the magnetic flux density received by each receiving coil. The position detection method of the moving body characterized by these. A transmission coil for transmitting magnetism provided on the moving body;
A reference tool in which a plurality of receiving coils that receive magnetism transmitted by the transmitting coil are arranged in the same plane;
Calculation means for calculating the distance from each receiving coil to the transmitting coil based on the magnetic information received by the plurality of receiving coils, determining the coordinate position of the transmitting coil based on the obtained distance information, and outputting it When,
A position detection apparatus for a moving body, comprising:   The position detector for a moving body according to claim 2, wherein the transmission coil is formed of a printed board.