JPH03199988A - Position locating apparatus - Google Patents

Abstract

PURPOSE:To enhance locating accuracy to a large extent by mounting the correction means provided to the receiving part of a master station correcting the return signals from respective suboffices corresponding to an elapse time so that the amplitudes thereof become constant. CONSTITUTION:A sensitivity Time Control (STC) circuit 41 and a comparing circuit 42 are provided between the preamplifier 20 and demodulator 21 in a master station 10A and reference voltage V0 is supplied to the circuit 42 from a reference voltage generator 43. The circuit 41 corrects the return signal received from respective suboffices through a transmitting- receiving antenna 19 and the preamplifier 20 corresponding to the elapse time from the start of transmission so that the amplitudes thereof become constant to output the same to the circuit 42 of the next stage. The circuit 42 compares the level of the return signal outputted from the circuit 41 with that of the voltage V0 generated from the generator 43 and outputs the same to the demodulator 21 when the level of the return signal is equal to or more than that of the voltage V0. By this constitution, the effect of a reflected wave is removed by the circuits 41, 42 to make it possible to subject only a direct wave to the measurement of a distance and a distance measuring error is reduced to make it possible to improve locating accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a position locating device applied to automatic guided vehicles, movable carts, and the like.

[Conventional technology]

In recent years, automation of factory lines and transportation of goods to dangerous areas, etc.
Research into automatic guided vehicles is being actively conducted with the aim of saving labor and preventing danger. Currently, automated guided vehicles need to set a travel route in advance and are unable to travel outside of the predetermined route, so they lack flexibility, and there is a growing demand for high-performance automated guided vehicles that can autonomously travel along arbitrary routes. . To perform such autonomous driving.

It is essential to recognize the relative position within the driving area.

As shown in FIG. 5, the conventional positioning device is composed of a main station 10 and a plurality of slave stations 30tL to 30n.
The distance between the main station 10 and the slave stations sob to 30n is calculated from the round trip time of the radio waves from when 0 emits a transmission radio wave to receiving the reply radio waves from the slave stations 30IL to 30n, and the position of the self (master station) is calculated. It is something. The operation of the device will be described in detail below.

In the main station JO, a timing circuit 1 is a circuit for determining the start of orientation, and is connected to a counter 12 and an arithmetic circuit 3. This arithmetic circuit 13 includes an external ink-7
External device J5 is connected via Ace 14. The arithmetic circuit 13 receives the timing pulse from the timing circuit 12 and sends encoded information corresponding to a specific slave station to the modulator 16. This encoded information is modulated into an analog waveform by a modulator 16 so that it can be emitted as a radio wave, and is then modulated into an analog waveform by a power amplifier 17. The signal is transmitted to the slave station via the circulator 181 and the transmitting/receiving antenna 19. The circulator 18 controls the flow of signals, and the signal from the power amplifier 17 is output to the antenna 19, and the signal from the antenna 19 is output to the preamplifier 20, but the signal from the power amplifier 12 is not output to the preamplifier 20. Transmission and reception signals can be separated, and the antenna 19 can be used for both transmission and reception.

In the slave stations 30 to 30n, the transmission radio waves from the master station are received by the transmitting/receiving antenna 31, inputted to the demodulator 32 via the circulator 32, demodulated into encoded information by the demodulator 32, and then encoded by the decoder 34. The decoded information is compared with the decoded information of the local station.

Different decoding information is assigned in advance to the decoder 34 of each slave station 30g to 3θn, and when it matches the encoded information from the master station 10, it is recognized that the own station has been selected, and the encoded information is sent to the modulator 35 again. and sends a reply to the main station 10.

In the main station 10, the antenna 19 receives a return radio wave from one selected specific slave station, and after demodulating it in the demodulator 2 via the circulator 18 and preamplifier 2o, it outputs it to the arithmetic circuit 13. The arithmetic circuit 13 decodes the reply signal, and if it matches the encoded information it has encoded, the arithmetic circuit 13 decodes the corresponding slave station 301L to 3.
It determines that the signal is from 0n and outputs a pulse indicating completion of orientation to the counter 12. The counter 12 measures the time between the first orientation start pulse and the orientation end pulse, and transfers the result to the arithmetic circuit 13 again. The measurement time of the counter 12 is the sum of the time for the radio wave to travel back and forth between the main station JO and the slave stations 30a to 30jOn and the delay time of the electronic circuit, but since the delay time of the electronic circuit can be corrected in advance, the linear equation The distance between the master station and the slave station is calculated inside the arithmetic circuit 13.

here.

t: Distance between master station and slave station (-1o; Radio wave round trip time between master station and slave station (lI) C: Radio wave propagation speed 3 x 108 (m/a) t: Counter 12
measurement time (slΔt: delay time inside the electronic circuit (
It is sl.

As described above with reference to FIG. 5, the conventional position locating device is capable of measuring the distance between the master station and the slave station selected by the master station.

Next, by measuring each distance between the master station and multiple slave stations,
The principle of locating the position of the main station will be explained using FIG. In FIG. 6, for example, three slave stations 301 to 30c are installed in the measurement area 36 (!1+3'1) e (
12e F2) e (3:5+73), and the main station 10 is at (x(, yo)), ("11y1) + (X2aY2
) e (X5+73) is a known position, while b (!o;7(,) is an unknown target position.
- In the figure, if the distance between the main station 10 and each slave station 30a to 30a is tl z t2 * tM, then the target position (x
l) ty(1) is the intersection of three circles whose centers are at the positions of the respective slave stations 30a to 30c and whose radius is the distance from the master station 10.

Assuming that each circle is 11 yen, 21 yen, and 3, the equation inside the can is as follows. Solving equation (2) above, we can find the intersection of the three circles (xO*
) to y.

becomes. Here, the variable AK * BKe C1 (K=1
+ 2 e 3 ) is.

6-. Note that when the number of slave stations is three or more, it is clear that the accuracy of the oriented position (xo+yo) is improved by performing the calculation of equation (3) multiple times.

As explained above, the conventional positioning device.

The position of the main station 10 is determined by determining each distance from the time taken for the radio waves to travel back and forth between the main station 10 and the plurality of slave stations 30h to 30son.

[Problem to be solved by the invention]

However, in the above conventional position locating device, when an obstacle 37 exists between the main station 10 and the slave station 30m as shown in FIG. 4, the direct wave originally used for distance measurement is blocked by the obstacle 37.
Distance measurement will be performed using reflected waves A, B, etc., and the correct distance will not be obtained.

The above will be explained with reference to FIGS. 3(al) and (bl).

Figure 3 (ml indicates the transmission radio wave (transmission signal) transmitted by the master station and the reply radio wave (reply signal) from the slave station;
bl represents the output of the demodulator 2 for the signal in (a) above. When there are no obstacles between the master station and the slave station, the earliest timing t with respect to the transmission signal (straight wave) from the master station 1o, as shown by the broken line in the figure. (corresponding to distance to), a reply signal from the slave station is received.

However, if there is an obstacle between the main station and the slave station, the direct wave will not be received by the obstacle and the timing 1.1 will include a delay due to one reflection. (corresponding to distance t1), the reply signal (reflected wave A) from the slave station is received. For this reason, 1 originally t. At a timing that includes a delay of t with respect to the timing of , a distance error of 1.-1°, which corresponds to a time of 1l-1o, will occur.

Furthermore, there are many propagation paths for one reflected wave other than those mentioned above.

For example, reflected wave B, which is generated by reflection from a wall surface opposite to reflected wave A, is one of them. However, in either case, as with 1 reflected wave A, it is for a direct wave.

It includes a delay time determined from the propagation path of the reflection, and when the direct wave is out of visual line of sight with conventional positioning equipment,
There was a problem that distance measurement was inaccurate.The present invention was made in view of the above points.1It is possible to exclude the influence of reflected waves and measure only direct waves, which can greatly improve location accuracy. The purpose is to provide a position locating device.

[Means to solve the problem]

The present invention provides a receiving section of a master station with an STC (8 snsitivity T1m
5Control) circuit is provided, and a comparison circuit is provided at the next stage of the STC circuit to constitute a position locating device.

[Effect]

Since the positioning device of the present invention is configured as described above, the return signal received by the master station from the slave station is amplified in the STC circuit to compensate for the attenuation of radio waves due to the distance between the master station and the slave station. After that, it is output to the next stage comparison circuit. The comparison circuit compares the reply signal with the output of the reference voltage generator installed inside the main station.If the reply signal is a reflected wave, there is attenuation of the reflection in addition to the attenuation of the radio wave. Base 9 - If the voltage is below the standard voltage, the comparator circuit will not output a signal to the next stage demodulator. On the other hand, when the reply signal is a direct wave, it is only the attenuation of the radio wave, so it becomes higher than the reference voltage, and the comparison circuit outputs the reply signal to the demodulator at the next stage.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the present invention provides an STC circuit 41 and a comparison circuit 42 between the preamplifier 2θ and the demodulator 21 in the main station 10 in addition to the circuit shown in FIG. The circuit 42 is configured to supply a reference voltage from a reference voltage generation circuit 43. The rest of the circuit is the same as the circuit shown in FIG. 5, so the same parts are denoted by the same reference numerals and detailed explanation will be omitted. The above STC circuit 4 is as follows.

The amplitude of the return signal from each slave station received via the transmitting/receiving antenna 19 and preamplifier 20 is corrected according to the elapsed time from the start of transmission so that the amplitude is constant.

It is output to the comparison circuit 42 at the next stage. This comparison circuit 42 is
The reply signal outputted from the STC circuit 4 is the reference voltage V generated by the reference voltage generation circuit 43.

The response signal is the reference voltage V. If it is above, it is output to the demodulator 21.

Next, the operation of the 8TC circuit 41 will be explained with reference to FIG.

Fig. 2 (at is the output signal of the preamplifier 20,
is the signal when it passes through the STC circuit 4], and fcl in the figure is the signal when it passes through the STC circuit 4].
The time variation of the gain, which is a characteristic of the TC circuit 41, is shown in the same figure (di
represents the distance attenuation of radio wave propagation. When there are no obstacles on the propagation path, the propagation characteristics of radio waves are attenuated in proportion to the square of the propagation distance, that is, the elapsed time from the start of transmission, as expressed by the following equation. )).

4πr LP = (7) 2 (4) here.

L: γ: Therefore.

Attenuation in free space Propagation distance +m3 Wavelength (- Due to the propagation characteristics of radio waves.

As shown in Figure 2 (a), when the elapsed time is short (when the distance between the master station and the slave station is short), the amplitude of the reply signal A1 received by the master station 1 OA from the slave station is large; is long (main station/
(when the distance between slave stations is long), the amplitude of the reply signal A3 becomes small. For this reason, as shown in Figure 2 [el], as the elapsed time increases,
If the gain of the amplifier of the TC circuit 41 is increased, the amount of attenuation (formula (4)) due to the propagation characteristics of radio waves can be corrected.
1, the amplitude of the reply signals (B1 to BJ) remains constant regardless of the elapsed time.

In the position locating device configured as described above.

As shown in Figure 3, when there is no obstacle between the master station and the slave station, the direct wave has a constant amplitude V regardless of the distance between the master station and slave station due to the STC circuit 4, and the reference voltage is generated. Vessel 43
The reference voltage V. is set lower than the constant amplitude V, the comparator circuit 42 outputs a reply signal (direct wave) to the demodulator 21 at the subsequent stage.

On the other hand, if there is an obstacle between the master station and slave station.

Reflected wave A and reflected wave B are attenuated by one reflection in addition to the attenuation of the radio wave propagation characteristics corrected by the amplification of STC circuit 4, so the amplitude of the signal input to comparator circuit 42 is based on the standard. Voltage V. The following is a reply signal (reflected wave A and reflected wave B) to the demodulator 21 after the comparison circuit 42.
is not output.

Then, the signal outputted from the comparison circuit 42 is sent to the arithmetic circuit 13 via the demodulator 2, and orientation processing to the main station 10 is performed.

〔Effect of the invention〕

As explained above, according to the present invention, the 870 circuit and the comparison circuit can exclude the influence of reflected waves and use only direct waves for distance measurement, thereby reducing errors in distance measurement. The location accuracy can be greatly improved.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a position locating device according to an embodiment of the present invention, Fig. 2 is a diagram for explaining the operation of the 870 circuit which is a feature of the present invention, and Fig. 3 shows the effects of the present invention. Figure 4 is a signal waveform diagram for explaining transmission and reception operations, Figure 4 is a layout diagram of the device when an obstacle exists between the master station and slave station, Figure 5 is a circuit diagram showing a conventional position locating device 13-. FIG. 6 is a diagram showing the principle of location using the position location device. 10k...Main station, 11...Timing circuit, 12.
... Counter, 13... Arithmetic circuit, J4... External interface, 15... External device, 17... Power amplifier. 18... Circulator, 19... Transmitting/receiving antenna. 20...Preamplifier, 41...870 circuit, 42.
...Comparison circuit, 43...Reference voltage generator.

Claims (1)

[Claims] The master station emits transmission radio waves to multiple slave stations, and the distance between the master station and slave stations is determined from the round trip time of the radio waves from the time the radio waves are emitted until receiving the reply radio waves from each slave station, and the position of the master station is determined. In a position locating device, a correction means is provided in the receiving section of the main station and corrects the amplitude of the return signal from each slave station according to the elapsed time from the start of transmission so that the amplitude is constant, and A comparison circuit that compares the level of the response signal with a reference voltage and outputs the response signal when the level is equal to or higher than the reference voltage, and means for locating the position of the main station based on the response signal output from the comparison circuit. A position locating device characterized by comprising: