JPS61164488A - Position detecting method of linear motor - Google Patents

Abstract

PURPOSE:to accurately detect the position by synchronizing and outputting the output signal of a trailing position sensor with that of a preceding position sensor. CONSTITUTION:When an encoder (not shown) generates an output signal A2, the value of a signal A2 of the falling time of a waveform shaping signal S1 is stored in a latch circuit LC1, and the value of a signal A2 of the rising time is stored in a latch circuit LC2. Comparators CO1, CO2 compare the outputs of latch circuits LC1, LC2 with the signal A2, and apply signals V1, V2 to an EOR circuit. The output of a flip-flop FF is inverted by the rise of the output EO of the EOR circuit to obtain a signal S2''. A selector SELEC switches input signals S1, S2'' by a select signal SS.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for detecting the position of a linear motor.The present invention relates to a method for detecting the position of a linear motor. In particular, the present invention relates to a method of detecting the position of a linear motor, which is suitable for improving the position accuracy.

[Background of the invention]

Conventional linear motors are equipped with a rotary pulse generator, etc. on the pile mover to detect the position and speed of the mover, as described in Japanese Patent Application Laid-Open No. 57-166874. Therefore, wiring is connected from the mover to the control circuit, and long-distance movement is not considered, and contact-type encoders do not take into account high-speed movement.

[Purpose of the invention]

An object of the present invention is to provide a method for detecting the position of an IJ near motor that enables long-distance movement, high-speed running, and highly accurate position detection.

[Summary of the invention]

A method for detecting the position of a linear motor according to the present invention includes a position sensor such as an encoder that detects the position of a movable element, and a switch that switches between the position sensors.
In a device that outputs an output signal of a position sensor such as a subsequent encoder in synchronization with an output signal of a position sensor such as a previous encoder, in order to synchronize the output signal of the subsequent position sensor, The waveform is shaped and synchronized at each position of the value of the analog output signal, which is the basis of the output signal of the subsequent position sensor, at the edge of the output signal of the previous position sensor.

In addition, the following points are to be noted.

In order to achieve the above object, the present invention provides an analog output of the position sensor at the time of switching from the rising edge and falling edge of the position sensor in order to synchronize with the previous signal to be switched when switching the position sensor. The waveform is shaped and synchronized using the value as a reference value.

[Embodiments of the invention]

An embodiment of the method for detecting the position of a linear motor according to the present invention will be described with reference to the drawings.

FIG. 1(a) is a schematic side view parallel to the traveling direction of a linear motor used for implementing an embodiment of the present invention, and FIG.
B) is an enlarged view of the part α in (A), Figure 2 is a block diagram of the control circuit, Figure 3 (A) is a layout diagram of each part, and (B) is the switching FIG. 4 is a block diagram of the position correction circuit, and FIG. 5 is a signal timing chart at the time of encoder switching.

In other words, (a) in Fig. 1 is an overall configuration diagram. First, there are n sets (n≧1.integer) of teeth 3 UI l with 1 set of 3 phases.
v, , Wl ~3tLa, Vm, wa,
Carp #4U+ l v,, Wl ~4UM, Vl,
wa, magnetic pole position detector 5 U 1 , V + , W
+~5U,.

v-, VV-, and linear encoder sensor LS+ ~L
It is composed of S. 3.4.5 in the figure is a generic term for the set of teeth, coil, and magnetic pole position detector.

The linear encoder sensors L8+ and LSx are
The position of the encoder etc. before and after detecting the position of the movable element 1 has been improved, and the magnetic pole position detector 5V+ ~ 5W
1, 5V2 to 5W2 also serve as switches related to sensors.

The mover 1 is supported by a support mechanism (not shown) so that a constant gap is maintained parallel to the teeth 3,
It is possible to move freely. Further, the magnet 2 is arranged in the movable element 1, and the linear encoder magnetized plate 6 is arranged in a place where it is not affected by the leakage magnetic flux of the magnet 2.

This linear encoder magnetized plate 6 includes linear encoder sensors LS1 to L8. All detection elements of the magnetic pole position detector 5 are held parallel to the magnet 2 with a constant gap.

Therefore, to explain the case where n=1, mover 1
The magnet 2 provided in 2 has N poles and 8 poles arranged alternately at a pitch of π, and teeth 3 U+, V+.

It is magnetized (magnetized) perpendicularly to the upper surface direction of Wl and mover 1,
The magnetic pole position detectors 5V+ + 50+ and 5W+ are each arranged at a pitch of 2π/3 at the positions shown in the figure.

Teeth 3U+ to 3W are arranged with a width of π and a pitch of 4π/3.

FIG. 2 shows a block diagram of the control circuit, and the operation of the above-described configuration will be explained next.

That is, the coil 4 for driving the mover 1
U+, V+, and VV+ are connected to an inverter 7, and a DC power source 13 is connected to the drive power source of the inverter 7. An amplifier 8 is also connected to the inverter 7, and controls the duty of the current flowing through the inverter 7 based on the difference between the signal from the current detector 14 and the first-rate command signal from the calculation section 11.

The calculation unit 11 includes a magnet 2 provided on the movable element 1,
The magnetic pole position is detected by the magnetic pole position detector 5VI.

5U+ and 5Wl are used to detect the signals, and the magnetic pole position distributor 9 generates signals for each phase to be energized to the coil 4.

The magnetic pole position detector 5 is adjusted so that it outputs "H" when there is no magnetic flux from the magnet 2 and when the magnetic pole is the south pole, and outputs "L" only when it is the north pole.

The output of the linear encoder sensor LS+ is caused by the linear encoder magnetized plate 6 attached to the movable element 1 moving together with the movable element 1, and the output of the linear encoder sensor LS+ is generated by the pattern magnetized on the linear encoder magnetized plate 6. This device obtains a synchronous analog output such as a sine wave, and by shaping this signal, outputs of 0H" and "L" are alternately output in the form of pulses.

In the case shown in FIG. 2, the linear encoder sensor L
The output of S2 is uncertain in the n Hn or "L" state and does not become a pulse output.

However, when the mover 1 moves to the right side in the figure, the linear encoder magnetized plate 6 overlaps both the linear encoder sensors L8+ and LS2, and the linear encoder sensor L
S, and L 82 A pulse output is obtained, but since the ON pole of the magnet 2 attached to the mover 1 comes to the magnetic pole position detector 5Vz, the output of the magnetic pole position detector 5V2 is '
When L'', the output of the linear encoder sensor L S x is selected by the linear encoder switch 10 according to the output of the magnetic pole position distributor 9.
is input.

The command unit 12 commands the current to be applied to the coil 4, and the speed of the movable element 1 is proportional to the current to be applied, and is inputted to the calculation unit 11 as a speed command.

The flow has been briefly explained above, but it will be explained in more detail with reference to FIG.

FIG. 3A shows the arrangement of the magnet 2 provided on the movable element 1, the magnetic pole position detector 5, the linear encoder magnetized plate 6, and the linear encoder sensor L8.

Also, (b) is the switching waveform diagram, where:
The magnetic pole position signal waveforms from Ul to W2 correspond to the magnetic pole position detectors 5U1 to 5W2, the signal waveforms of Sl and 82 correspond to the linear encoder sensors LSs and LS2, respectively, and the signal waveform S is as follows. S! And S! It is created by using the logical sum of or a gate circuit such as a selector.

Therefore, when the movable element 1 is located at the position shown in FIG.
L'', ``H'' at the S pole, V! at the position where Ul changes from H'' to ``L''! is “L”.

W+ is in the lHII state.

In addition, a magnetic pole position detector 5 that is not affected by the magnetic field of the magnet 2
V2, 5Ul, 5W2 are in the H'' (7) state, and as the movable element 1 moves to the right, the magnetic pole position signal U+=Wz changes as shown in the figure.

one! 7'c, the encoder output signal Sl of the IJ near encoder sensor LSl is output from the corresponding magnetic pole position detector s
The magnetic pole position signal Ul is 3 output signals from V+ to 5W.
The encoder output signal S2 is selected when the logical product of three -Wl is 'L', and the encoder output signal S2 is the magnetic pole position signal U2 to W2.
is selected when the logical product is "L".

However, in the span SP section shown by the dashed line, the encoder output signals SI and S2 are prioritized so that the output of the linear encoder sensor in the moving direction of the movable element 1 (in this case, the encoder output signal 82) is not selected at the same time. Alternatively, the priority may be set depending on the magnitude relationship of n.

Further, although the above description is for up to n=2, the same applies to the case where n>2.

Furthermore, the above description is based on the encoder output signal SL of the linear encoder sensor LS1 and the linear encoder sensor L.
It can be used with high accuracy when the encoder output signal S2 of S2 is synchronized, but in order to synchronize these two encoder output signals 81 and 82, the linear encoder sensor must be installed with high precision. There is a problem that cannot be solved.

FIG. 4 is a circuit diagram that takes the above-mentioned problem into account, and can be countered by adopting the method described below.

To explain its configuration, an analog output signal At of the linear encoder sensor LSI is connected to a comparator CO.

The output of this comparator CO is the waveform-shaped 'L''
It is connected as an input to the selector 8ELEC with a logic signal of "H", and the latch circuits LC+ and LC
2 as a clock input.

Moreover, the analog output signal A2 of the linear encoder sensor Ls2 is connected to the comparator co2, the comparator CO1, and the A/D converter AD, respectively.

The output signal of the A/D converter AD is sent to the latch circuits LC and L.
C2, and converts the analog output signal A2 of the linear encoder sensor LS2 into a digital signal.

The outputs of latch circuits LC+ and LCz are each D/A
Through converters DA+ and DAz, comparator Cot
, Co2, and the output of the comparator CO+, CCh is connected to the input of EOR, whose output is J/
Flip-flop circuit FF such as flip-flop circuit
The output of the flip-flop circuit FF is connected as the other input of the selector 5ELEC.

The select signal SS that selects the input of the selector 5ELEC is
The pull-up resistor R pulled up to the power supply V is connected to the switch T.
I am creating this by switching over.

This select signal SS includes magnetic pole position signals U+ -W+ and U2 to W, which are related to the output signal of the magnetic pole position detector 5 described above.
It is equal to the logical AND with 2.

The signal selected by this select signal SS is output as the output signal sO of the selector 8ELEC.

Next, the operation will be explained using FIG. 5.

Linear encoder sensor L8*, LS2 (Daf.

The output signals A, , A, are sinusoidal as shown in the figure. In the example in this figure, the analog output signal A
With respect to I, Doujin 2 has a delayed phase of π15,
This shows a case where a mechanical positional deviation occurs in the linear encoder sensor LS2 with respect to L S t, and also shows when the linear encoder sensor is switched.

As mentioned above, SL and S2 are waveform shaping output signals,
The analog output of the linear encoder is waveform-shaped at the zero cross position, and SI is the linear encoder sensor L.
8+ corresponds to the output, and 8t corresponds to the output of the linear encoder sensor L8z.

In fact, the signal output that is most necessary when switching from linear encoder sensor LSs to LS2 is as shown by the output signal SO, even if there is a mechanical positional deviation of linear encoder sensor LS2 with respect to LSI. , the phase shift between the analog output signals Al and A2 related to the linear encoder sensor output must be corrected by the switching point P.

The signal Sz' shows the case without phase correction.

In this case, the amount of phase shift is added to the time L'' at the switching point (9) P, causing an error with respect to the actual position.

Next, phase correction will be explained.

When the analog output signal A2 is generated at the linear encoder sensor L S t, the rise of the waveform shaping output signal S+ υ
At the falling edge of the waveform shaping output signal S1, the voltage value of the analog output signal A2 of the linear encoder LSg is converted to digital using the A/D converter AD shown in FIG. and the start-up value in the launch circuit LC2, respectively, and the D/A converters DA and DA2.
By setting the analog output signal A2 related to the linear encoder analog output as the reference value (in this case, negative input) of the connected comparator, the comparator CO
The output signals of V+ and Vz in FIG. 5 are obtained at the outputs of + and Cot.

Furthermore, by passing the output of the comparator CO+ + COz shown in FIG. 4 through the EOR circuit R, it is possible to obtain the output signal of EO shown in FIG. The lower shed can be synchronized with the zero cross position of the analog output signal A1 of the linear encoder.

Furthermore, since the output of the EOR circuit R is input to the flip-flop circuit FF, the output EO of the EOR circuit
By inverting the output of the flip-flop circuit FF at the rising edge of FF, B, // shown in FIG. 5 is obtained.

By the above operation, the input signals S+ and S2" of the selector circuit 5ELEC are switched by the select signal 88, and even if there is a mechanical positional deviation in the linear encoder sensor LSz at the switching point) P, the position It is possible to obtain a signal that has been corrected.

In addition to the above, the present invention is an m-phase IJ near motor (m is an integer) using n sets of coils, teeth, a magnetic pole position detector, a linear encoder, etc. Corrects mechanical positional deviations that occur when switching linear encoder sensors, making switching easy
There is a changeable effect. As a result, it is possible to expect the effect that an infinite length linear encoder can be constructed with high accuracy.

〔Effect of the invention〕

According to the present invention, by using one short linear encoder magnetized sheet metal and a plurality of sensors to construct a linear encoder, a long-distance linear encoder can be constructed with high precision. At the same time, the position can be detected with high precision.

[Brief explanation of drawings]

FIG. 1(a) is a schematic side view parallel to the traveling direction of a linear motor used for implementing an embodiment of the present invention, and FIG.
B) is an enlarged view of the part α in (A), FIG. 2 is a block diagram of the control circuit, FIG. 3 (A) is a layout diagram of each part, and (B) is a switching waveform diagram. , FIG. 4 is a block diagram of the position correction circuit, and FIG. 5 is a signal timing chart at the time of encoder switching. 1...0T mover, 2...Magnet, 3...Teeth,
4... Coil, 5... Magnetic pole position detector, 6... Linear encoder magnetized plate, 7... Inverter, 8...
Amplifier, 9...Magnetic pole position distributor, 10...Linear encoder switch, 11...Calculation section, 12...Command section, 13...DC power supply, 14...Current detector, LS・
...Linear encoder Sen (other, noun)

Claims (1)

[Claims] 1. Equipped with a position sensor such as an encoder that detects the position of the movable element and a switch that switches between these position sensors, and the output signal of the position sensor such as the encoder that follows the output signal of the position sensor such as the encoder that follows. In a device that outputs signals in synchronization, in order to synchronize the output signals of the subsequent position sensors, the output signal of the subsequent position sensor at the edge of the output signal of the previous position sensor is A method for detecting a position of a linear motor, characterized in that the waveform is shaped and synchronized at each position of the value of a base analog output signal.