JPS62203009A - Apparatus for detecting position of moving body - Google Patents

Abstract

PURPOSE:To enable positional detection and positioning with high accuracy, by counting the output of an encoder while an error is corrected at each time when the position of a body to be detected is detected. CONSTITUTION:Bodies 11 to be detected are arranged to a guide path 10 being a fixing means at an arbitrary interval and a moving body 20 is moved while guided by the guide path 10. A detection part 21 for detecting the bodies 11 to be detected and an encoder 22 for measuring a moving distance are provided to the moving body 20 and, further, a first position detecting circuit 23, an error detecting circuit 24 and a second position detecting circuit 25 are provided to said moving body 20. The circuit 23 counts the number of the bodies 11 to be detected which are detected by the detection part 21 to output a rough position signal and the circuit 24 takes AND with the output signal of the encoder 22 during a period when the detection part 21 detects the bodies 11 to be detected and outputs the detection signal to output an error signal. The circuit 25 subtracts the error signal from the output signal of the encoder 22 at a cycle being the timing detecting the bodies 11 to be detected to perform correction.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a position detection device for positioning a moving object.

B1 Summary of the Invention The present invention is for detecting the position of a moving object, in which a detected object is provided at an arbitrary interval along a guide path to indicate the position. A first position detection circuit that includes a detection section that detects the detected object and outputs a rough position detection signal by currenting the detected object; an error detection circuit that detects an error during a detection signal output period of the detection section; By providing a second position detection circuit that subtracts the error detection signal from the output signal of the encoder at intervals of the timing at which the body is detected, errors due to differences in the moving direction of the moving body are eliminated.

BACKGROUND OF THE INVENTION Conventionally, as a positioning device for a moving object, a rack and pinion system, as shown in FIG. 5, has been widely used. That is, a drive wheel 2 is provided which runs on a fixed rack 1 and meshes with this rack, and this drive wheel 2 is connected to a movable body 3. The drive wheel 2 is driven by a motor (not shown). To position the moving body 3, when a target position value is given to the motor by the control device, the motor rotates;
The movable body 3 moves completely above the rack 1 by rotating the drive wheel 2 connected to this rotating shaft. This movement is detected as the current position by the encoder 4 attached to the drive wheels 2 or the motor, and the moving body 3 is stopped at the point where the target value and the current position match.

Figure 6 shows a detection method used when the moving distance is relatively short.A code mark (detected part) 5 made of a reflective plate or a permanent magnet plate is provided on the side surface of the rack 1, which is the fixed side, and the moving object 3 is A detector 6 consisting of a reflected light sensor and a Hall element is provided on the side to detect the code mark 5, and the positioning is performed in the same manner as shown in Fig. 5 when the target value and the detected value of the current position match. The moving body 3 is stopped.

D0 Problems to be Solved by the Invention In the case shown in Fig. 5(a), backlash and so-called backlash in the drive system (mechanical system) always occur, resulting in errors even when stopping at the same target position. occurs. This state is shown in Figure 5(b), where the horizontal axis shows
~[Phase] indicates the stop position of the moving body 3. For example, if you move from position ■ to the right in the drawing and set position ■ as the target stop position, you will actually stop at point A due to play in the drive system, but if you set the same position ■ as the target stop position, position ■ If it moves further to the left, it will stop at point B. In other words, if the moving direction is reversed, even if an attempt is made to stop at the same target position, the stopping position will shift and the accuracy will be poor.

Further, when the moving distance is long, the processing of the rack 1 is complicated and requires a lot of man-hours, and since it is a contact type, there are also problems in terms of maintenance.

In addition, in the case of the method shown in Fig. 6, the coded detection parts 5t must be attached to the entire length of the rack 1, which complicates the work. Things have become extremely difficult.

Finally, a conventional position detection device for positioning moving objects! t has the problem of being unsuitable for relatively long-distance movement, particularly of several hundred meters.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a position detection device that can detect the position of a moving body moving over a relatively long distance with high precision.

E9 Means for Solving Problem This invention, as shown in FIG. 1, is a system in which objects to be detected 11, such as permanent magnets, are arranged at an arbitrary interval of several meters on a guide path 10, such as a rack, which is a fixed side. will be established.

The moving object 21, which moves while being guided by the guide path 10, is equipped with a detecting section 21 consisting of a Hall element, etc., for detecting the object 11 to be detected, and an encoder η for measuring the moving distance.
is provided. Furthermore, this moving body silver has a detection section 21.
During the period when the first position detection circuit n counts the number of detected objects 11 and outputs a rough position signal, and the detection section 21 detects the detected objects 11 and outputs the detection signal. an error detection circuit for correcting the error of the detected object 1;
A second position detection circuit 5 is provided which subtracts the error detection signal from the output signal of the encoder B for the entire timing period when 1 is detected.

Waveform A in Figure 2 shows the output signal of the first position detection circuit B, which is sequentially added to the n-th and n+1 detected objects 11 and output. Output (waveform B
) is set each time the detected object 11 is detected, and error correction is applied.

G. Example An embodiment of the present invention will be described in detail below with reference to the drawings.

Figure 3 shows the 1. FIG. 3 is a circuit diagram showing a specific example of the second position detection circuit n, 25 and the error detection circuit m.

That is, the first position detection circuit n includes an amplifier AMP1,
Comparator COMI with hysteresis characteristics to prevent chattering, NAND circuit NAND 1
, NAND 2 , rise detection circuit Ul , U2
, one-shot multivibrator M, up/down counter C01, AND circuit ANDI, AND2
, NOT circuits N0TI to N0T5, an R-S flip-flop FF, and OR circuits ORI and OR2.

The error detection circuit consists of a comparator C0M2, a /t circuit N0T6, N0T7, and an AND circuit AND3.
．． It has a NOR circuit NOR, a counter CO2, a latch circuit R9, and a digital-to-analog converter c1.

Further, the second position detection circuit 5 includes an amplifier AMP2, an AND circuit AND4, AND5, , /IF counter c
o31 Digital-to-analog converter C2, adder ADI
, AD2° multiplexer MP, comparator L/-Y C0M
3. It also has analog/digital converters C3, C4, and an analog switch As.

The operation of the present invention as described above will be explained.

Prior to explaining FIG. 3, the concept of the present invention will be explained using FIG. 4.

When a permanent magnet is used as the detected object 11, this permanent magnet has a width of W. In addition, since the hysteresis comparator COM 1 is used to prevent chattering as one element for detecting this magnet, the counter C
A position error occurs between the coarse position output of 01 and the output of encoder n during normal rotation and during reverse rotation. In other words, in FIG. 4(a), the counter COI at the time of stop rotation shown by waveform C
The output of encoder 4 is n+1 and the output of encoder 4 (waveform D) is Vo
The position at the time is x5, while the position at the time of reversal is /
When the COI output (waveform F) is n+1, the position when the encoder outputs (waveform G) Vo is X2, and a position error of distance Xw occurs.

Waveform A is the output of the Hall element (detection part) 21, B is the output of the comparator COMI during forward rotation, and E is the CO during reverse rotation.
The output of MI, H, is the output of comparator C0M2.

Therefore, in the present invention, in order to correct Xw, the correction is performed using the waveform H of C0M2 as a reference, as shown in FIG.

For example, now the target value is TEN −n, vE = V
1 (VXW (V1 < Vmax - Vxw)
When is given, the moving body force rotates normally as shown in (b),
There is no problem because position XII is outside the width W of the magnet 11 regardless of whether it is reversed. Here, vmax is the maximum output setting value of the encoder, and vXW is the encoder output during distance Xw.

Next, when it is between a certain position xo e X1 in W, depending on the direction of movement,
ax(2) N=n+1, O<vE<VXW02
There are two states.

So, f! tXot standard), the position error can be removed by setting N=n"l r O<Vg<Vxw in both forward and reverse rotations. To do this, during forward rotation, VE > Vmax- V when satisfying Vycw
Find g=■g'-(Vmax-Vxw)', N
= n+l.

FIG. 3 is based on the above idea, and the moving body moves along the guide path 1o in the right direction (forward rotation) or the left direction (reverse rotation). It generates an output (human waveform in Figure 4) when it passes nearby. This output is amplified by an amplifier AMP1 and then output to comparators COI and CO2, respectively. The signal of the hysteresis converter 200M1 is detected (waveform C in FIG. 4) and an output signal is applied to each gate of NAND 1 and NAND 2.

On the other hand, a positive signal is applied to terminal T during forward rotation, and a negative signal is applied during reverse rotation, and one of these signals is directly connected to N.
applied to the gate of AND 1, but the other one is N0
Through T3 to the gate of NAND 2, and further to OR2 →
It is applied to each gate of NAND 1 and N0T3→ORI→NAND 2. Therefore, when the movable body is moving in the forward rotation direction, NAND 1 generates an output, and the rising detection circuit U1 detects this and outputs N0TI.

The N0T4 is passed through to invert the 7th and 70th FF, and is applied to the up terminal of the counter COI through AND1 to count the detected object 11. This count value is a rough value that simply counts the number of detected objects 11 [signal N
(Waveform C in Figure 4). The same applies to the case of reverse rotation; in this case, NAND2, U2.

A signal is applied to the DOWN terminal of COI at the route of AND 2, and counter COI produces the output shown in FIG. 4C.

The detection signal of the detected object 11 amplified by the amplifier AMP 1 is output to the position X by the comparator C0M2 for error correction.
o (waveform C in Figure 4), and the signal is detected at position X1
The voltage continues for Xw, which covers the width W of the object 11 to be detected, and is applied to one gate of the AND circuit AND3.

The other gate of AND3 receives the ratio signal vE detected by the incremental encoder n, and the amplifier AMP2
Since it is applied through 'i+-, when C0M2 generates an output, AND3 turns on and the output is sent to counter C.
Apply O2. CO2 is reset by the signal from the NOT circuit NOT 6 when COM 2 is turned off, but it is not set when COM2 is turned on and counts the distance signal from the encoder n. This count value is latched to the latch circuit R on the condition that the detection signal Pi (or P2) of the rise detection circuits Ul and U2 is applied to the latch circuit R through the NOR circuit NOR and the NOT circuit N0T7i, and is The converter C1 generates the output Vxw of the encoder 22 over the distance Xw. A distance signal vxW from the encoder for distance Xw is applied to adder AD2. Since the maximum output setting value Vmaz of encoder n has been applied to adder AD2 in advance, this AD
The calculation of Vmax-Vxvr is performed in Z, and the analog output signal is converted into a digital signal by analog-to-digital converter C3 and output to multiplexer MP. Note that the signal Vmax-V:rw is also applied to the analog switch As and the comparator C0M3, and the signal VXW is also applied to MP through the analog-digital converter C4.

On the other hand, the output of the encoder 22 amplified by AMP2 is passed through the AND circuit AND4' to the up counter CO3.
Applied to the terminal. CO3 is the start-up detection circuit Ul,
It is loaded in synchronization with the detection signals PI and P2 of U2, that is, at position XO during forward rotation and at point Xl during reverse rotation, but at this time, the signal Xw from C4 is preset through MP during forward rotation. Also, at the time of reverse rotation, a signal of Vmax -Vxw is preset through C3t-. In this case, the moving object rotates in the normal direction, so Xwf is preset, and the value of CO3 is set using the digital-to-analog converter C2.
is converted into an analog signal vE and applied to the adder ADI, and is also applied to the comparator C0M3 and compared with Vmax - Vxw, so that Vr,'> Vm
At the time of ax -VXW, the analog switch AS is turned on and Vmax-VxW is applied to ADZ. Therefore, the second position detection circuit 5 outputs VF.

A position signal of = Vz' - (Vmax - VXW) is output, and this output vE has no error due to the movement direction difference Xw explained in FIG. 4 (&). That is, as shown by the dotted line portion of the encoder output in FIG. 4(b), it is considered as an extension of the solid line and errors due to directional differences are removed.

Note that the output of the comparator C0M3 is applied as a trigger to each of the first position detection circuits M;
This is to perform adjustment when the output N of l is between the positions Xo and X1.

■9 Effects of the Invention According to the present invention, a counter is set for counting the output of the encoder while correcting the error each time the position of the detected object is detected, so even if an error occurs, it will accumulate. Since this method does not occur, highly accurate position detection 1 positioning is possible, making it possible to apply it over long distances of several hundred meters or more.

In addition, the processing and installation work of racks that will serve as guideways will also be carried out in Section 5.6.
Compared to the one shown in the figure, it has the advantage of being very simple and maintenance-free since it is a non-contact type.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of the present invention, FIG. 2 is a configuration diagram of the present invention, FIG. 3 is a specific circuit diagram showing an embodiment of the present invention, and FIGS. 4(a) and (b) are For the purpose of explanation, FIGS. 5 and 6 are configuration diagrams showing conventional position detection devices, respectively. DESCRIPTION OF SYMBOLS 10... Guide path, 11... Detected object, addition... Moving body, 21... Detection part, n... Encoder, n...
First position detection circuit, 24...Error detection circuit, 5...
-Second position detection circuit. Figure 1 Figure 2 □□□---- Figure 3 Figure 4

Claims (1)

[Claims] An encoder is provided on a movable body moving along a guide path, and the position of the movable body is detected based on the output signal of the encoder, in which objects to be detected are provided at arbitrary intervals on the guide path, A detecting section that detects the detected object and generates an output signal is provided in the moving object, and the detection signal of the detecting section and the forward and reverse moving direction signals of the moving object are logically multiplied together to detect the detected object. an error detection circuit that detects the output of the object to be detected and, during the duration of the detection signal, obtains an AND with the output signal of the encoder to obtain an error signal. , this error signal is subtracted from the set maximum output value of the encoder to obtain a difference signal, and when the difference signal is smaller than the output signal of the encoder with the timing at which the detected object is detected as a period, the difference signal is calculated from the encoder output. A position detecting device for a moving body, comprising: a second position detecting circuit that performs subtraction and correction.