JPS61169910A - Detecting method of positional shift - Google Patents

Abstract

PURPOSE:To correct the variation of a detected output due to the variation of the height of a detected body and to improve the detecting accuracy of positional shift by controlling the gain of a signal processing system so that the sum of the output voltages of two detecting coils fitted to the detected body is always fixed. CONSTITUTION:The AC output voltages a1, a2 of the detecting coils 1, 2 are amplified by pre-amplifier circuits A1, A2 and their outputs b1, b2 are converted into DC voltages c1, c2 by a rectifier smoothing circuits B1, B2 and then inputted to AGC amplifier circuits C1, C2. The outputs d1, d2 of the circuits C1, C2 are added by an adder D and its output (e) is fed back to the circuits C1, C2. The circuits C1, C2 control their gain at an equal rate so that the feedback signal (e) coincides with a reference value (r). Although the signal (e) is changed in accordance with the height between the coils 1, 2 and the detected body, the variation of the outputs d1, d2 due to the height (h) can be corrected by controlling the gain of the circuits C1, C2 so that the signal (e) is kept at a fixed value.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a device that detects the amount of positional deviation from a detected object, and is mounted on an unmanned vehicle, for example, to detect the amount of positional deviation from a guide. Regarding equipment.

(Prior Art and Its Problems) Conventionally, as a method for guiding unmanned vehicles, methods using a guide cable, a band-shaped metal plate, or a magnetic plate as a guide have been proposed, and some of them have been put into practical use. (Automatic transportation technology: P268 published by Triceps, Japanese Patent Application Laid-Open No. 59-059808) The guidance of an unmanned vehicle is to determine how far the vehicle body moves in the left or right direction with respect to guides that are installed substantially continuously along the driving path. It detects the deviation and performs steering by an appropriate amount in the direction opposite to the deviation. When an induction cable is used as the object to be detected, that is, the guide, an alternating current is passed through the induction cable, and the magnetic field generated is detected by a detection coil mounted on an unmanned vehicle. Further, when a metal plate or a magnetic body is used as a guide, an excitation coil is provided in addition to the detection coil, and the change in the alternating current magnetic field generated by the excitation coil due to the metal plate or magnetic body is detected by the detection coil.

In either case, in order to know the amount and direction of deviation from the guide, two detection coils 1.2 are installed on the unmanned vehicle, one each on the left and right sides of the guide, as shown in Figure 4. be installed on. Since the output of each detection coil has output characteristics as shown in Figure 5, the amount of positional deviation can be determined according to the output of the detection coil, and the direction of deviation (
left or right). Another commonly used method is to rectify the output voltage of the rain detection coil, then electrically calculate the difference between the two, and obtain the magnitude and direction of the deviation from the magnitude and polarity of the difference signal.

As described above, in the conventional method, the magnitude of the output voltage of the detection coil is used to determine the amount of positional deviation. However, the output voltage of the detection coil changes not only due to the horizontal displacement from the object to be detected, but also due to the vertical direction, that is, the height variation.

FIG. 6 shows the differential value of the outputs of the two detection coils shown in FIG. 4. The magnitude of the differential output changes depending on the height between the detection coil and the object to be detected. Therefore, for example, in an unmanned vehicle, if the height of the chassis changes due to its bounce or the weight of the load, the output voltage of the detection coil will not be constant. As a result, there is a drawback that an appropriate amount of steering cannot be obtained and accurate driving cannot be achieved.

(Object of the Invention) In view of the above-mentioned drawbacks, the present invention corrects fluctuations in the detection output due to height fluctuations between the positional deviation detection device and the detected object, and corrects the output voltage for horizontal positional deviation. The purpose of the present invention is to maintain the output voltage constant regardless of the above-mentioned height fluctuation (Structure of the invention). This positional deviation detection method is characterized by controlling the gains of signal processing systems connected to both coils so that the sum of amplitudes is always constant.

(effect) The present invention will be explained in detail with reference to FIG. 4.7.

When the magnetic field created by the current flowing through the cable 3 is detected by the two detection coils 1 and 2 as shown in FIG. 4, the voltage obtained across both coils becomes K as shown in FIG. 7.

As can be seen from this figure, the detection voltage of the detection coil 1.2 has a normal distribution characteristic whose magnitude changes depending on the height h from the cable 3. The range indicated by M in the figure means a range that can be approximated by a straight line among the output voltages of the rain detection coils 1 and 2 when the cable is between the two detection coils 1 and 2. In this range of M, rain detection coil 1,
The output of No. 2 can be approximated by a straight line having the same slope and different polarity with respect to the horizontal positional deviation X. Therefore, within the range M, the sum of both output voltages is constant regardless of the value of the positional deviation X. As the height h of the detection coil changes, the slope of the output voltage with respect to the horizontal positional deviation xK changes, but the sum of the outputs of both coils remains a certain constant value in this case as well.

Therefore, by controlling the gains of the two amplifier sections in the two signal processing systems connected to the rain detection coils at equal rates so that the sum of their outputs always remains constant, it is possible to reduce the amount of noise from the cable. Changes in the output voltage of the detection coil due to changes in height h can be corrected.

The above has described the case of detecting the magnetic field created by the current flowing through the cable, but in addition to the two detection coils, it is also possible to detect the distribution of the magnetic field generated by the excitation coil installed in the middle of one detection coil. Even when detecting changes caused by certain metals or magnetic materials, the output of the rain detection coil has the same detection characteristics as shown in Figure 5, and the above method can correct output fluctuations due to the height of the detected object. can.

(Embodiment) FIG. 1 is a block diagram showing a basic embodiment of the present invention. AC output voltage of detection coil 1.2 al tal
is amplified by preamplifier circuits AI and A2 to an amplitude that can be rectified. Further, if there is a difference in output level due to a difference in the characteristics of the detection coil 1.degree.2, it can be corrected by the preamplifier circuit.

Furthermore, the rectifier/smoothing circuits Bl and B2 convert the outputs b1 l b of the preamplifier circuits AI and A2 into DC voltages els
After converting to C1, an amplifier circuit whose gain can be controlled externally (hereinafter referred to as AGC amplifier circuit: Auto Ga1nCo
This is called a ntrol amplifier circuit. ) is input to C1,c.

The output d1+G of the AGC amplifier circuit C, , C, is the adder circuit D
K large input, its output e (5=d1+ds) is AGC
It is fed back to the amplifier circuits C, , C, as a gain control signal. The two AGC amplifier circuits C1, C, set K so that this feedback signal e becomes equal to the reference value r.
, the gains of both are controlled in equal proportions. As shown in FIG. 5, the feedback signal e changes depending on the height between the detection coil 1.2 and the detected object, but the KAGC is used to keep the feedback signal e constant as described above.
By controlling the gain of the amplifier circuit C1°C1, its output d1. The variation due to the height hK of dl can be corrected.

FIG. 2 shows the detection signal according to the present invention (AGC in diagram t41).
2 shows the differential value of the output voltages dt, ds) of the amplifier circuit. As is clear from a comparison with FIG. 6, according to the present invention, the detection output based on the height hK can be corrected, and the value of the horizontal position shift can be detected with high accuracy from this output voltage.

Note that the preamplifier circuits AI and A2 in FIG. 1 can be omitted if the output of the detection coil 1.2 is sufficiently large.

In addition, the preamplifier circuits AI and A2 are AGC amplifier circuits,
The AGC amplifier circuits ci and C2 after the rectifying and smoothing circuit can also be omitted.

In addition, when an excitation coil is provided in addition to the detection coil 1.2, the detection coil 1.2 directly detects the magnetic field generated from the excitation coil even when there is no detected object.
This causes errors in the correction method according to the present invention. In this case, as shown in FIG.
, B2 rear stage (or front stage) K bias adjustment circuit El
, E2 is connected and there is no detected object, DC output voltage C
It is sufficient to adjust so that 1°C1 becomes zero.

In the above embodiment, an adder circuit and an AGC amplifier circuit are used to keep the sum of the outputs of the two detection coils constant.
However, it is also possible to zero-convert the DC voltage after the rectifying and smoothing circuit and obtain the same effect on software using a microcomputer or the like.

The positional deviation detection device according to the present invention is not only useful as a sensor for detecting the guide of an unmanned vehicle, but also can be applied to, for example, detecting the position of a magnetic body as a buried metal body.

(Effects of the Invention) As described above, according to the present invention, fluctuations in the detection output due to fluctuations in height between the positional deviation detection device and the detected object are corrected, and the detection output voltage with respect to horizontal positional deviation is corrected. In other words, the accuracy of detecting positional deviation can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a basic embodiment of the present invention;
FIG. 2 is a diagram showing changes in the height of the differential value of the output voltage shown in FIG. The figure shows the conventional positional deviation detection method, Figures 5 and 6 show the detection voltage of each detection coil and the differential value of both voltages, and Figure 7 shows the height of the detection voltage of the detection coil. In the figure, 1.2 indicates the detection coil, and 3 indicates the cable. -~ Fig. 2 -~ 74 Fig. 3 Cable V+a, b: Detection coil \I--L- Height h of the coil! When V2O mouth. V2Ob: However, when #h2, when h3, h+<h2<h3

Claims (3)

[Claims] (1) In a method of magnetically detecting positional deviation with the detected object using two detection coils, each detection A positional deviation detection method characterized by controlling the gain of a signal processing system connected to a coil. (2) Positional deviation detection according to claim 1, wherein the object to be detected is made of an electric wire, and the two detection coils detect a magnetic field created by an alternating current flowing through the electric wire. Method. (3) The object to be detected is made of metal or magnetic material,
The two detection coils detect changes in the distribution of the alternating current magnetic field generated by the excitation coil separately provided between the two coils, due to the object to be detected. Positional deviation detection method.