JPH0259909A - Truck guiding device - Google Patents

Abstract

PURPOSE:To improve detecting accuracy and to reduce the cost of the title truck guiding device by providing the device with a bandlike magnet arranged along a traveling course and a magnetic sensor fixed to a truck and arraying plural magnetic resistance elements at a fixed interval. CONSTITUTION:The magnet tape 1 arranged on a floor 2 along the traveling route is uniformly magnetized in the thickness direction. An antenna part 4 is formed on the lower face of the truck 3 in its advancing direction and the MR elements 8a to 8h are arranged on the antenna part 4 at the prescribed interval. When a control signal is outputted from a control means inputting a detecting signal from a magnetic sensor consisting of the MR elements 8a to 8h to a steering mechanism, the steering angle of the steering is changed and the truck 3 is kept at a normal state. Consequently, the cost of the device can be reduced, mutual elements are not allowed to interfare with each other and the reliability of the device can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bogie guiding device for guiding a bogie along a predetermined travel route.

In order to make conventional mobile carts unmanned, it is necessary to have a guide device for the carts to move within a factory or warehouse according to a preset route.

As such an 81'271 device, a method in which a cart is run on a rail, or an electromagnetic induction method in which a high-frequency current is passed through a guide wire stretched on the floor are generally known. However, the former method involves high construction costs, and the latter method has problems such as being susceptible to electromagnetic noise.

Therefore, as shown in Japanese Unexamined Patent Application Publication No. 59-154511, magnetic strips are arranged on the floor according to the traveling route, and a plurality of saturable coils are provided at the bottom of the truck. Something that would run on top of the vehicle has been proposed.

However, in the above conventional structure, it is necessary to create a saturable coil by winding the coil around a saturable core.
It takes time to manufacture the saturable coil, which increases the cost. Further, even when the coil is mechanically wound, the winding operation becomes complicated, which also results in an increase in cost.

In addition, the thickness of the coil increases the size of the saturable coil. In this case, it is necessary to arrange a large number of saturable coils in parallel in a narrow space, so the spacing between the saturable coils becomes narrow, causing interference between the coils. As a result, there have been problems such as poor detection accuracy.

Therefore, the present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a low-cost trolley guiding device that can improve detection accuracy.

In order to achieve the above-mentioned object of the present invention, the present invention provides a bogie guiding device for guiding a bogie along a predetermined running route, and a belt-shaped magnet disposed along the running route, a magnetic sensor attached to the magnetic sensor, in which a plurality of magnetic resistance elements are arranged at regular intervals, and a control means for controlling a steering mechanism of a cart traveling along the magnet based on a detection signal from the magnetic sensor. It is characterized by having

Fraud - November 1 With the above configuration, when the trolley runs outside of its normal state, the resistance value of the magnetic resistance element will change depending on the degree of deviation, so the The detection signal changes. Therefore, a control signal is outputted to the steering mechanism from the control means into which this detection signal is input, and the steering angle of the steering wheel is changed. As a result, the truck can be returned to its normal state.

Since such control operations are performed constantly while the trolley is running,
It becomes possible to reliably run the trolley along the travel route.

One embodiment of the present invention will be described based on FIGS. 1 to 11.
This will be explained below.

As shown in Figures 1 and 2, the magnetic tape (width: 50mm, thickness 0.8+n) 1 placed on the floor 2 according to the running route is placed in the thickness direction (perpendicular to the floor). It is magnetized like -. A cart 3 is provided on the magnetic tape 1, and the left and right wheels 3a . . . run along the magnetic tape 1 while straddling the magnetic tape 1. As shown in FIG. 3, an antenna section 4 is provided on the lower surface of the truck 3 on the traveling direction side so as to be perpendicular to the traveling direction of the truck 3. This antenna section 4 has 10
Eight MR elements 8a to 8h are provided at intervals of mm. As shown in FIG. 4, the MR elements 8a to 8h each have two differential output pins 9a+49a.
z ~9h, H9hz are provided, and the MR element 8a
When a DC voltage (+Vcc) is applied to 8h to 8h, a DC voltage proportional to the strength of the magnetic field is output from the differential output pins 9a+9az to 9h+ and 9h2, as shown in FIG. Further, the distance between the MR elements 8a to 8h and the magnetic tape 1 is 30±10M, and each of the MR elements 8a to 8h is provided with a detection circuit 1.
0a to 10h are connected.

Here, the detection circuit 10a includes an analog switch Il.
a, a capacitor C1a, an AC amplifier 12a, a capacitor C2a, a synchronous rectifier circuit 13a, and a comparator 14a15a.

The analog switch lla converts the DC voltage from the differential output pins 9a, 9az of the MR element 8a into an AC signal by switching in synchronization with the clock of the oscillator 16.

The AC amplifier 12a amplifies a weak AC signal proportional to the magnetic field. - The capacitor C1a and the capacitor C2a remove DC components of the signals from the analog switch lla and the AC amplifier 12a, respectively.

The synchronous rectifier circuit 13a demodulates only the signal 4 component that is synchronized with the clock and noise components that are asynchronous with the clock (for example, offset and drift of the AC amplifier 12a).
is removed, and a signal demodulated to the detection signal of the MR element 8a is output.

The comparators 14a and 15a are connected to the synchronous rectifier circuit 13.
The signal from a is compared with a reference voltage applied via resistors R1a to R2a, and if the absolute value of the signal output is higher than the absolute value of this reference voltage, an ON signal is output.

Here, in the above description, the detection circuit 10a was described, but the detection circuits 10b to 10h have a similar configuration.

Next, the detection circuits 10a to 10h are connected to a control circuit 17. In this control circuit 17, the detection circuits 10a to 1
According to the detection signal from 0h, the positional relationship between the magnetic tape 1 and the truck 3 is determined, and a control signal is output to the steering mechanism 18 of the truck 3. This steering mechanism 18
Then, the steering angle of the steering wheel is changed according to the above control signal.

In the above configuration, the bogie guiding device of the present invention operates as follows.

First, when a bogie running switch (not shown) is turned on, a DC voltage is applied to the MR elements 8a to 8h, and a DC voltage proportional to the strength of the magnetic field is output from the differential output bins 9a, 9a2 to 9h+9hz. . This DC voltage is
As shown in FIG. 6, there is a drift, but this can be removed by the capacitor C1a. Next, the analog switches lla to llb are connected to the clock signal from the oscillator 16 (shown in FIG. 5). Accordingly, the DC voltage is switched to output an AC signal to the capacitor C1a.

The reason for converting a DC signal into an AC signal in this way is that the output voltage of the MR elements 8a to 8h is a few millivolts, which is very small, so amplifying it with a DC amplifier would not yield a high S/N ratio. I can't. Therefore, in order to obtain a high S/N ratio and to remove the drift of the MR elements 8a to 8h, the signals are converted into AC signals. Incidentally, the duty cycle of the clock signal of the oscillator 16 is configured to be 50% in order to obtain a high S/N ratio. Next, the DC component of the AC signal is removed by the capacitors C1a to C1h, and a signal having the waveform shown in FIG. ) is output. This AC amplifier 12a~
After the DC component of the signal from 12h is removed by capacitors C2a to C2h, it is applied to synchronous rectifier circuits 133 to 13h. The synchronous rectifier circuits 13a-13h rectify according to the clock signal from the oscillator 16, demodulate only signal components that are synchronized with the clock, and demodulate noise components that are asynchronous to the clock (for example, the offset of the AC amplifiers 12a-12h). (drift) are removed. As a result, as shown in FIG.
It is output at 4h and 15h. This comparator 14a1
5a to 14h and 15h, the signal from the synchronous rectifier circuit 13a and the reference voltage given through the resistors R1a to R2a are compared, and if the signal is higher (or lower) than the reference voltage, an ON signal is output. do. Thereafter, the positional relationship between the magnetic tape 1 and the cart 3 is determined according to this signal. This determination is performed as follows.

That is, as shown in FIG. 9(a), the MR elements 8a to 8h
When the distance d between the magnetic tape 1 and the magnetic tape 1 is 3ON, the upper surface of the magnetic tape l is the north pole, and the trolley 3 is running normally, the control circuit 1 is output from the comparators 14c to 14f.
An ON signal is output to 7. As a result, the control circuit 17
A control signal is output from the steering mechanism 18 to maintain the steering angle as it is. On the other hand, Fig. 9(b)
As shown in (C), d = 30 + u, the upper surface of the magnetic tape 1 is the N pole, but if the trolley 3 is traveling shifted to one side, the four comparators output the same as above. However, comparator 1 outputs when normal.
It is output from a different comparator from 4c to 14f.

For example, when an ON signal is output from the comparators 14a to 14d or the comparators 14e to 14h to the control circuit 17, the control circuit 17 outputs the ON signal to the steering mechanism 18.
A control signal is output that causes the steering angle to be in the opposite direction to the direction of deviation. After that, when the bogie 3 returns to normal running and the ON signal is output from the comparators 14C to 14f to the control wholesale circuit 17, a control signal is output from the control circuit 17 to the steering mechanism 18 to maintain the steering angle as it is. Ru. In this way, the trolley 3 can be made to travel along a preset route.

Incidentally, depending on the deviation of the truck 3, a corrected steering angle as shown in Table 1 below is given.

[Margin below]

Distance d between Table 1, Table 2 8h and magnetic tape 1 = 30 **
However, the cart can be guided normally even within the range of d=30*±10mm. In this case, as shown in Table 2 below, 0N-
The number of bits is different.

[Margin below]

In the case of d = 15 + u, it is preferable because the number of 0N-bits changes (for example, 6) when the antenna section 4 is moved left and right.
This is not desirable. Therefore, d=30■Maro±
A range of 10 mm is preferred.

Further, in the above embodiment, the antenna section 4 is installed perpendicular to the traveling direction of the trolley 3, but the structure is not limited to this. For example, as shown in FIG. 10, the antenna section 4 may be installed parallel to the running direction of the trolley 3, or as shown in FIG. It is also possible to do so. However, in this case, it should be noted that the number of 0N-bits is different and that the MR elements 8a to 8h should be arranged so that the distances from the floor 2 are all the same.

As described above, according to the present invention, it is possible to reliably run the trolley along the travel route. At this time, the magnetoresistive element used in the bogie guidance device does not require winding a coil like a saturable coil. Therefore, complicated work becomes unnecessary, and the manufacturing cost of the device can be reduced. Furthermore, since there is no coil, there is no interference between the elements.

Therefore, there are effects such as being able to improve the reliability of the bogie guidance device.

[Brief explanation of the drawing]

FIG. 1 is a plan view schematically showing the bogie guidance device of the present invention, FIG. 2 is an enlarged side view of FIG. 1, FIG. 3 is an enlarged plan view of FIG. 1, and FIG. 4 is a plan view of the bogie guide of the present invention Block diagram of the device, No. 5
The figure is the waveform diagram of the oscillator, Figure 6 is the characteristic diagram of the MR element, and Figure 7 is the waveform diagram of the oscillator.
The figure is a characteristic diagram when a magnetic field is applied to the MR element, Figures 8 (a) to (d) are waveform diagrams in the detection circuit, and (a) is a waveform diagram of the signal output from the capacitor C1a, Figure (b) is a waveform diagram of the signal output from the AC amplifier, Figure (c) is a waveform diagram of the signal output from the synchronous rectifier circuit,
Figure 9 (b) is a waveform diagram of the signal output from the comparator, Figures 9 (a) to (C) are explanatory diagrams showing the relationship between the magnetic tape and the antenna section, and Figures 10 and 11 are the antenna section. It is an explanatory view when the installation angle of is changed. 1...Magnetic tape, 3...Dolly, 8a-8h
...MR element, 10a to 10h...detection circuit, ll
a~llh...Analog switch, 12a~12h・
...AC amplifier, 13a-13h...synchronous rectification circuit,
14 a to 14 h, 15 a to 15 h - comparator, 17... control circuit, 18... steering mechanism. Patent applicant: Murata Machinery Co., Ltd.

Claims (1)

[Claims] (1) In a bogie guidance device that guides a bogie along a predetermined running route, a strip-shaped magnet arranged along the running route and a plurality of magnetic resistance elements attached to the bogie are arranged at regular intervals. A bogie guidance device comprising: magnetic sensors arranged at intervals; and a control means for controlling a steering mechanism of a bogie running along the magnets based on detection signals from the magnetic sensors.