JPS6237853B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting the position of a moving body using guided radio.

In the automatic operation of moving objects that move along a fixed route, such as railway vehicles, various types of transportation, or industrial transport facilities, it is essential to continuously and periodically know the position of the moving object on the ground at all times. The most typical example is a linear motor car.

A typical technique that meets this demand will be explained with reference to FIG. 1, 2, and 3 are conductors, each of which is bent into a waveform with a period P, and mutually P/
The guided radio line 4 is formed by laying the wires on a plane with the wires shifted by three. Therefore, line 4
has a repeating structure with a period P, and when a high frequency current (50 to 200 kHz) is applied to the antenna 5 mounted on a moving object, a three-phase sinusoidal voltage will be induced on the track 4 as the moving object moves. . The z-axis is taken in the longitudinal direction of the line 4, and the coordinate of the antenna 5 is z,
Assuming that the voltages induced between conductors 1 and 2, 2 and 3, and 3 and 1 are V ₁₂ , V ₂₃ , and V ₃₁ , respectively, these can be expressed by the following equations.

V ₁₂ =kcos(2π/P)z……(1) V ₂₃ =kcos(2π/P){z+(P/3)} =kcos{(2π/P)z+(2π/3)}…( 2) V ₃₁ =kcos(2π/P){z+(2P/3)} =kcos{(2π/P)z−(2π/3)}…(3) k is a constant determined by the structure of the line 5, etc. be.

Here, for each voltage in equations (1) to (3), the positive phase voltage V _p and the negative phase voltage V _o are defined by the following equation.

V _p =V ₁₂ +e ^-j2 〓 ^/3 V ₂₃ +e ^j2 〓 ^/3 V ₃₁ ...(4) V _o =V ₁₂ +e ^j2 〓 ^/3 V ₂₃ +e ^-j2 〓 ^/3 V ₃₁ ...(5) Substituting equations (1) to (3) into equations (4) and (5) and rearranging them gives the following equations.

V _p = (3/2) ke ^j2 〓 ^z/P ………(6) V _o = (3/2) ke ^-j2 〓 ^z/P ………(7) The phase difference between V _p and V _o When φ is assumed, φ=∠V _p −∠V _o =4πz/P (8). Note that ∠ is a symbol representing the argument of a complex quantity.

That is, every time z increases by P/2, φ also shows a linear increase of 2π, and by knowing the value of φ, the position of the moving object (the position of the antenna 5) can be changed to P/2.
This means that continuous measurement can be performed in 2 cycles.

However, when the line 4 and the antenna 5 are brought close to each other to reduce coupling loss, or when the antenna 5 has dimensional restrictions, the coupling distribution is distorted and odd-order spatial harmonic components are Occur. For example, V ₁₂ can be expressed as follows.

(n=0, 1, 2, 3, ......, C _2o+1 : Fourier coefficient) In this case, in a three-phase three-conductor system, there is a phase difference of 2π/3 between V ₁₂ , V ₂₃ , and V ₃₁ harmonic components that are integral multiples of 3, such as 3rd, 9th, etc., are not included in the signal processing circuit due to reasons such as However, since other odd-order harmonic components cannot be eliminated, there is a problem in that errors occur in position measurement.

The present invention has been made based on the above, and aims to provide a moving body position detection method that enables error-free position detection by eliminating spatial harmonic components.

In the position detection method of the present invention, the length l of the guided radio line in the longitudinal direction of the antenna mounted on the mobile object is calculated as follows: l=mP/(2s+1) (m is any integer, s=-1, 2, -4, 5, −
7, 8, -10, ......).

Alternatively, the half angle θ _a when viewing both sides of the antenna mounted on the mobile object from the center of the guided radio line is θ _a = mπ/(2s+1) (m is any integer, s = -1, 2, -4, 5, -
7, 8, -10, ......).

Hereinafter, the present invention will be explained in detail based on FIGS. 1 and 2.

The antenna 5 is a rectangular loop having longitudinal sides AD, BC of length l and axial sides AB, CD of length b, and the line 4 has a width of 2a and its center line (in the figure dotted line) on the z-axis. Moreover, the positional relationship in the cross section between the line 4 and the antenna 5 is as follows:
As shown in Figure 2, the z-axis is upright on the paper, conductors 1, 2, and 3 are in the yz plane, and the plane of the antenna 5 is in a plane parallel to the yz plane. It is assumed that the center lines of 5 are completely aligned.

First, the mutual inductance between the line 4 and the antenna 5 will be considered. It is assumed that a normal sequence current (or a negative sequence current) is passed through the line 4 according to the reversibility theorem, and at this time, the mutual inductance between the two may be determined from the magnetic flux interlinking with the antenna 5.

The currents in conductors 1, 2, and 3 are respectively I ₁ , I ₂ , and I ₃ , and I ₁ = I ......(10) I ₂ = e ^j2 〓 ^/3 I ...... (11) I ₃ = e ^{- j2} 〓 ^/3 I ......(12). This current is the positive sequence current of line 4.

Since the width 2a of the line 4 is usually small compared to the period P, only the z component of each conductor current is dominant,
The part perpendicular to this can be ignored. Therefore, the vector potential of the magnetic field generated by I ₁ only needs to consider its z component A _1z , and is: 〓 ² A _1z = 0 ...... (13) [〓 ² = (∂ ² / ∂x ² ) + (∂ ² /∂y ² )+(∂ ² /∂
z ² )] must be satisfied.

Since the phase amplitude of the current I ₁ in the conductor 1 is independent of z and its shape changes periodically with a period P, A _1z at point E is considered to have the following form.

Here, r, θ are the coordinates of point E, K _o (2nπr/
P) is an nth-order modified Bessel function of the second kind, and C _o is a constant determined by the shape and dimensions of the conductor.

Similarly, the z components A _2z and A _3z of the vector potential of the magnetic field generated by I ₂ and I ₃ have the following form.

The z component of the vector potential as a whole is becomes.

Here, n=-1, 2, -4, 5, -7, 8, -
In the case of 10, 11, -13, 14, ......, 1 + 2 cos2 (n + 1) π / 3 = 3 ...... (18), and if n is an integer value other than the above, 1 + 2 cos2 (n + 1) π/3=0 ......(19) Therefore, A _z can be rewritten as:

Here, 〓 is 1+2cos2(n+1)π/3=3
This symbol means that addition is performed only for n that satisfies the function.

The coordinates of the AD part of antenna 5 are (r _a , θ _a ),
Let the coordinates of the BC part be (r _a , -θ _a ), and the antenna 5
Letting the coordinates of the center of z _a and the number of turns of the antenna coil be N _a , the mutual inductance M between the antenna 5 and the line 4 is given by the following equation.

M=(N _a /I)∫ ^za+l/2 _za-l/2 {A _z (r
_a , θ _a ) −A _z (r _a , −θ _a )}dz ......(21) Substituting equation (20) into equation (21) and integrating this term by term, M Obtain a general expression for .

As mentioned above, the structure of the track 4 is flat, and the track 4
If the shape of the antenna 5 is symmetrical, the shapes of the two match, and geometric symmetry is ensured in the relative positional relationship between the two, then the even-order term of n appears in equation (22). First, only odd terms need to be considered. Therefore, M becomes as follows.

In addition, 〓 is s=-1, 2, -4, 5, -7, 8,
−10,……(2s+1=−1, 5, −7, 11, −
This symbol means to add only s of 13, 17, -19, ......). On the right side of equation (23), the term s=-1 (2s+1=-1) is the fundamental wave, and the other terms are higher-order harmonics that cause position measurement errors.

Here, (2s+1)πl/P=mπ……(24) [l=mP/(2s+1)] Or, (2s+1)θ _a =mπ……(25) [θ _a =mπ/(2s+1) ] When any of the following relationships holds true, the (2s+1)th harmonic becomes 0. Note that m=1, 2, 3,...
It is...

As is clear from the above description, according to the present invention, by specifying the shape and dimensions of the antenna, any unnecessary harmonic components can be canceled out, making it possible to detect a position without error.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams of one embodiment of the present invention, with FIG. 1 being a plan view and FIG. 2 being a side view. 1, 2, 3: conductor, 4: guided radio line, 5: antenna.

Claims (1)

[Claims] 1. A guided radio line consisting of N conductors (N is 3 or an integer greater than 3) arranged so as to have a repeating structure with a predetermined period P along a moving path. This guided wireless line is excited by an antenna mounted on a mobile object to induce an N-phase sinusoidal voltage, and the position of the mobile object is detected from the phase difference between the positive-sequence voltage and the negative-sequence voltage determined from these voltages. In the method of
7, 8, -10, . . . ). 2. A guided wireless line consisting of N conductors (N is 3 or an integer greater than 3) arranged so as to have a repeating structure with a predetermined period P is laid along the moving path, and this guided wireless line is In a method of inducing an N-phase sinusoidal voltage by exciting the line with an antenna mounted on a mobile object, and detecting the position of the mobile object from the phase difference between the positive-sequence voltage and the negative-phase voltage obtained from these voltages, inductive wireless The half angle θ _a when viewing both sides of the antenna mounted on the mobile object from the center of the track is θ _a = mπ/(2s+1) (m is any integer, s = -1, 2, -4, 5, -
7, 8, -10, . . . ).