JPS5853283B2 - Position detection method of moving object and its device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and device for detecting the position of a moving body using an open transmission line.

A conventional example of a system for detecting the position of a moving body using an open transmission line, for example, a leaky coaxial cable, will be described with reference to FIG.

Leaky coaxial cape with leaky slot 2 with one period P/
L/1 is installed along the travel path (Z-axis) of the moving object, and two antennas 3as 3b are mounted on the moving object.
The antennas 3a, 3b are each adapted to couple with a separate electric field or frequency component.

The signals received by antennas 3a and 3b are transmitted to amplifiers 4a and 4.
It enters the position pulse generator 5 via b.

The position pulse generator 5 generates position pulses in response to changes in the plate width, phase, etc. of the received signal as the moving object moves, and the position pulses are counted by a counter 6 to determine the position of the moving object. You can know.

If the received signals of the antennas 3a, 3b fall below a certain level, the position pulseless cost generator 5 will not operate correctly, and will not be counted during that time, resulting in a position detection error.

This point will be explained with reference to the graph shown in FIG.

Time T is plotted on the horizontal axis, and distance Z is plotted on the vertical axis.

It is assumed that when Z1≦26Z2, the signals received by the antennas 3a and 3b fall below a certain level, making it impossible to detect the position, and the moving object moves in the Z direction as shown by curve A.

Before entering the position detection impossible zone (KZI), the position pulse generator 5 generates position pulses t1 to t4 at times T1 to T4.
occurs, and when the position becomes impossible to detect (21≦Z≦Z2), the position pulse is no longer generated, and the position information as a whole becomes like the broken line B. When Z>Z2, there is a gap between the actual position and the position information. Errors will occur, and if there are many sections where position detection is not possible, these errors will accumulate and become non-negligible.

The present invention has been made in view of the above, and compensates for the shortcomings of the conventional method in which a position detection error occurs for a certain section when the level of the received signal of the antenna on the mobile object falls below a certain value, and eliminates the error. Another object of the present invention is to provide a position detection method for a moving body and a device thereof that can reduce errors to the extent that position detection accuracy is not affected.

The present invention makes it possible to realize a method and an apparatus for constantly storing information on the position pulse generation interval during normal operation, and performing position detection based on the position pulse generation interval information in the section where position detection is impossible. Embodiments of the present invention will be described below with reference to FIG.

The signals received by antennas 3a, 3b are transmitted to amplifier 4
a, 4b to the position pulse generator 5 and amplitude discriminator γ.

The position pulse generator 5 generates position pulses in response to changes in the properties (changes in amplitude, phase, etc.) of the output signals from the amplifiers 4a and 4b.

When the output signals from the amplifiers 4a and 4b are above a certain level, the amplitude discriminator γ emits a normal signal, which causes
The pulse generator 11 operates according to the position pulse generator 5, and the memory 9 stores the position pulse generator 5 and the timing pulse generator 12.
The pulse interval information calculated by the pulse interval measuring device 8 from the signal from the pulse interval measuring device 8 gradually increases.

The stored contents of the memory 9 are constantly replaced, so that it is possible to provide position transition information immediately before entering the position detection impossible section.

When entering the position detection impossible zone (Z, ≦26Z2), amplifier 4
The outputs of a and 4b are below a certain level, and the amplitude discriminator T
emits an abnormal signal.

At this time, the stored contents of the memory 9 are fixed, and the pulse interval generator 10 starts operating.

The pulse interval generator 10 calculates and generates an optimal position pulse based on the output of the timing pulse generator 12 and the output of the memory 9.

The pulse generator 11 operates according to the pulse interval generator 10 in the case of an abnormal signal.

If the moving object is moving at a constant velocity, it is possible to completely eliminate position detection errors, but if the moving object is moving at an uneven velocity as shown in curve A in Figure 3, it is difficult to obtain accurate position detection information. It gets weird.

However, position undetectable section length 5 = lZ2-211
is generally short, and the traveling speed cannot be suddenly reduced due to the inertia of the moving object. Therefore, if the position detection information immediately before entering the position detection impossible zone is used, the position can be detected with almost no error.

In the above embodiment, two signals are used and the case where the output signal becomes below a certain level is explained, but the present invention can also be applied to position detection using one signal without using two signals. Since it is applicable, it is necessary to set the criterion for abnormality to be, for example, when a low level continues for a certain period of time or more.

Periodic leakage structures (slots, etc.) are suitable for open transmission lines.
Even if it is not a parallel line or a single-braided coaxial line, any line that can detect the position based on the phase change in the electric field in the Z direction may be used.

Lines with a periodic leakage structure include not only leaky coaxial cables but also cross-guide lines and the like.

As described above, according to the present invention, it is possible to obtain a position detection system for a moving object and a device thereof that can eliminate errors or reduce errors to the extent that position detection accuracy is not affected even in areas where position detection is impossible.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a conventional example, Fig. 2 is an explanatory diagram of an embodiment of the present invention, and Fig. 3 shows the actual moving state of the moving body and the position detection error using coordinates of distance Z and time T. FIG. 1: Leaky coaxial cable, 2 slot, 3: Antenna,
4: Amplifier, 5: Position pulse generator, 6: Counter, γ
: Amplitude discriminator, 8: Pulse interval measuring device, 9: Memory, 1
0: Pulse interval generator, 11: Pulse generator, 12: Timing pulse generator.

Claims (1)

[Claims] 1. An open transmission line, preferably an open transmission line having a periodic leakage structure, is laid along the travel path of the moving object, and the electromagnetic field generated by the open transmission line is utilized. In the method for detecting the position of a moving object, the position of the moving object is estimated based on pre-stored position pulse generation interval information during normal operation in a section where the strength of the electromagnetic field is below a certain level. A method for detecting the position of a moving object. 2. In a position detection method for a mobile body that is equipped with an antenna that receives signals from an open transmission line and generates and counts pulses according to changes in the properties of the received signal, the interval between the pulses is A pulse interval measuring device that calculates pulse intervals using timed pulses, a memory that constantly stores pulse interval information, and a pulse interval generator that calculates new pulse intervals from the pulse intervals from this memory and issues a pulse generation command using the timed pulses. and a pulse generator that selects one of two pulse generation commands and operates in accordance with the command.