JPS62236655A - Origin detecting device for position control machine - Google Patents

Abstract

PURPOSE:To set a precise origin by shifting a shift member from a coarse origin by the adjustment shift quantity stored in a memory means and further shifting it until an output monitor signal is detected. CONSTITUTION:A position control machine M is composed of a drive mechanism 4 supported by a base 5 and interlocked with a motor 1 and a shift section 3 spline-coupled with this drive mechanism 4. The rotary shaft of the motor 1 rotating the drive mechanism 4 is directly connected to an incremental encoder 2 to shift the shift section 3. The output of the incremental encoder 2 is fed to a precise origin detecting circuit, and this output is further fed to a control circuit 10. The excitation and excitation direction of the motor 1 is controlled by a motor drive circuit 9. The motor drive circuit 9 is controlled by the output of the control circuit 10. A coarse origin detecting circuit 7 detects that the shift section 3 has reached a coarse origin from the motor drive circuit 9 and feeds it to the control circuit 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an origin detection device for a position control machine that sets a precise origin based on a coarse origin, and relates to origin detection at startup.

[Conventional technology]

Generally, a precision origin detection device for a position control machine using incremental control includes a coarse origin detector and a precision origin detector.

To detect this precision origin, it is common to first detect the coarse origin position at startup, move the mechanical moving part from this position, and set the first detected reference pulse of the incremental encoder as the precision origin. be.

However, as shown in FIG.
has an error range 101 because its detection accuracy is low. Here, if the reference pulse of the second incremental encoder is included in the error range 101, the position of the detected fine origin will differ depending on the rough origin detection position. That is, in the case of E in FIG. 8, the pulse 20B of the reference pulse train 200 of the incremental encoder is set as the precision origin detection position, and in the case of F, the pulse 207 is set as the precise origin detection position.

Therefore, a different precise origin is detected each time the origin detection operation is performed.

[Problem that the invention seeks to solve]

In view of the above problems, it is an object of the present invention to detect the same precise origin even when the output of an incremental encoder is detected within the coarse origin error range.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention includes a movable member movably provided in a position control coordinate system, a drive source for moving the movable member, and each time the movable member is moved by a constant movement distance DC. a movement amount detecting means for outputting a monitor signal to the moving member; and a coarse origin detecting means for detecting that the moving member is within a coarse origin detection error range DE in the position control coordinate system and outputting a coarse origin detection signal; a storage means for storing an adjustment movement amount DO (DO≧DB) until the moving member is moved from the coarse origin by more than a detection error range DH of the coarse origin; and a storage means for receiving the coarse origin detection signal and the monitor signal. When the movable member is moved from the rough origin by the adjustment movement amount DO stored in the storage means and then further moved and the next output monitor signal is detected, the movable member is moved by the position control. A technical means is adopted that includes a precision origin detection means that outputs a precision origin detection signal indicating that the coordinate system is at the precision origin.

[Effect]

In the apparatus of the present invention, the coarse origin detection means first detects that the moving member is within the coarse origin detection error range DE, and outputs a coarse origin detection signal. Then, the moving member moves from the position where this coarse origin detection signal is output to an adjustment movement 11DO (Do≧D) beyond the rough origin detection error range DE stored in the storage means.
E) is moved. The moving member is further moved from the position moved by this DO, and the precision origin detection means detects the monitor signal of the movement amount detection means that is output next,
The position of the moving member at this time is assumed to be the precision origin of the position control coordinate system, and a precision origin detection signal is output.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an embodiment of the present invention will be explained in detail below based on the drawings.

In FIG. 2, M is a position control machine. The position control machine M includes a drive mechanism 4 supported by a base 5 and interlocked with the motor 1, a moving section 3 spline-coupled to the drive mechanism 4, a mechanical dock 6a provided on the moving section 3, and a mechanical dock 6a provided on the moving section 3. It is composed of a mechanical stopper 6b that comes into contact with this mechanical dock 6a at one limit of movement. In order to move the moving part 3, the rotating shaft of the motor 1 that rotates the drive mechanism 3 is directly connected to the incremental encoder 2. The output of the incremental encoder 2 is input to the precision origin detection circuit 8, and this output is further input to the control circuit 1.
It is input to 0. The motor 1 is driven by a motor drive circuit 9.
The presence or absence of energization, the direction of energization, etc. are controlled. This motor drive circuit 9 is controlled by the output of a control circuit 10. The coarse origin detection circuit 7 detects from this motor drive circuit 9 that the moving section 3 has reached the coarse origin, and outputs this to the control circuit 10. The control circuit 10 is composed of a microcomputer, and its memory 11 stores data such as the free running distance and the total moving distance.

Note that the contents of this memory remain non-volatile even when the power to the apparatus of this embodiment is turned off.

In this embodiment, an RA with a battery backup function is used.
Constructed by M.

FIG. 3 shows the motor drive circuit 9 and motor l shown in FIG.
FIG. 2 is an actual wiring diagram of the rough origin detection circuit 7. The motor drive circuit 9 includes four switching elements 91, 92, 93, and 94 on each side of the bridge circuit, and drives the motor 1 between a pair of opposing connection points and drives the motor 1 between the other pair of connection points. Connect the voltage to the switching elements 92 on two adjacent sides
．． Resistors 95 and 96 are connected in series with each of 94. Each of these switching elements is controlled by a signal from a control circuit. The coarse origin detection circuit 7 amplifies this voltage drop across the resistor 95.96 with the operational amplifier 71,
Compare the voltage drop of the reference resistor 73 with the comparator 72,
The results are input to the control circuit. The reference resistor 73 is a variable resistor, and can adjust the voltage drop that becomes the reference voltage of the comparator 72.

FIG. 4 is a block diagram of the precision origin detection circuit 8 of FIG. 2. The pulses of the incremental encoder 2 that are input to the precision origin detection circuit 8 are A-phase.

There are B phase and C phase, and the C phase pulse is a pulse for each rotation of the incremental encoder 2, and the A phase and B phase pulses are a pulse for each rotation of the incremental encoder 2. The pulses for the A phase and B phase are divided into one rotation, and one rotation of the incremental encoder 2 generates 500 pulses. Generates a pulse. These A-phase and B-phase pulses are out of phase with each other, and based on this, it is determined whether the incremental encoder 2 is running in a normal or reverse direction.

ψ The A-phase and B-phase pulses are made into 2000 pulses per rotation of the incremental encoder 2 by a quadruple reverberation 81 to improve control accuracy. This output is the positive and negative pulse distribution 82
is input to the reference pulse detection timing selection 83, the former is for determining whether the incremental encoder 2 is running in the normal or reverse direction, and the latter is for selecting whether to detect the reference pulse at the rising edge of the pulse or at the falling edge. In the reference pulse detection 84, a reference pulse is detected from the C-phase pulse at the timing selected in the reference pulse detection timing selection 83. Then, the output of the positive/negative pulse distribution 82 and the output of the reference pulse detection 84 are sent to the control circuit 10. The pulse described in the following description of this embodiment is the output pulse of this reference pulse detection 84.

In the configuration of this embodiment described above, the drive source is the motor l, the movement amount detection means is the incremental encoder 2, and the monitor signal is sent to the incremental encoder 2.
The storage means is a memory 11, and the precision origin detection means is composed of a precision origin detection circuit 8 and a control circuit 10.

The adjusted movement amount DO stored in the storage means corresponds to the empty running distance stored in the memory 11.

Next, the operation of this embodiment will be explained in detail based on the drawings. FIG. 5 is a flowchart of the precise origin detection operation of this embodiment. The flowchart shown in FIG. 5 is executed every time the position control machine is started, and the precision origin of the position control machine is detected. In step 501 of FIG.
controls the motor drive circuit 9 to rotate the motor 1 and move the moving section 3 to the cloth in FIG. Then step 50
At step 2, the dog 6a and the stopper 6b come into contact and the movable section 3 reaches the rough origin. The rough origin detection circuit 7 detects this from a voltage drop across the resistor 95 or 96 of the motor drive circuit 9 due to an overcurrent flowing when the motor 1 is restricted. When this is detected, the control circuit 10 temporarily stops the moving unit 3 in step 503. In step 504, control circuit 1
0 reads the free running distance stored in the memory 11,
The moving unit 3 is moved to the left in FIG. 2 by this empty running distance.

Then, in step 505, the control circuit 10 moves the moving part 3 to the left, and in step 506, the precision origin detection circuit 8 detects the pulse of each rotation of the incremental encoder 2 at the current position of the moving part 3, and the control circuit 10 moves the moving part 3 to the left. 10 sets the position where this pulse is first detected as the precision origin detection position. In step 507, the control circuit 10 stops the moving section 3 at this precise origin detection position. In step 508,
The control circuit 10 calculates a shorter next free running distance from the total movement distance from the coarse origin detection position detected in step 502 to the precise origin detection position detected in step 506, and calculates the next free running distance that is shorter than this. The distance is stored in the memory 11. The calculation of the next free running distance will be described in detail later. In the series of operations shown in FIG. 5, in the first origin detection operation after the machine is assembled, the memory 11 stores in advance a temporary free running distance of an appropriate value, and this embodiment The operation shown in Figure 5 is performed based on the value.

In the next origin detection operation, the operation shown in FIG. 5 is performed based on the next empty running distance set in the first origin detection operation.

Next, FIGS. 6, 7, and 8 are also used to explain the relationship between the coarse origin detection position, the precise origin detection position, and the free running distance according to the operation shown in FIG. I will explain it to you.

Figures 6, 7, and 8 are the coordinate axes of the moving direction of the position control machine M! The rough origin 100 on the top and this error range 10
1, the pulse train 200 for each rotation of the incremental encoder 2, each of the pulses 201 to 209, the initial temporary free running distance 300, and the precise origin detection positions 401 to 404 set by the control circuit 10. This is what is shown. AF indicates each case based on the coarse origin detection position, and a to d are search distances for precise origin detection from the initial tentative free running distance to the precise origin detection position. The error range 101 is actually not very large in each figure, and is less than 10% of the pulse interval of the pulse train 200.

First, in FIG. 6, if the pulse 201 of the incremental encoder 2 is within the error range 101 of the coarse origin, the conventional technique shown in FIG. becomes inaccurate. However, in the present embodiment shown in FIG. 6, even in cases A and B in which the coarse origin is detected at both ends of the error range of the rough origin detection position, the distance from the coarse origin detection position is 300. Since detection of the precision origin starts from this point, in both cases A and B, the rising position of the pulse 203 is taken as the precision origin detection position. Then, the control circuit IO sets the next free running distance 300' and stores it in the free running distance storage means 11 so that the pulse 203 at the same position can be detected in the next precise origin detection operation. In this manner, the position of the rising edge of the pulse 20-3 is set as the precise origin detection position in subsequent precision origin detection operations as well.

Next, in the case of FIG. 7, the encoder 2 pulse 2
This is the case when there is 5. In case C, the position of the pulse 206 is set as the precision origin detection position, and in case D, the position of the pulse 205 is set as the precision origin detection position. However, in this embodiment, the control circuit 10 In the origin detection operation, the next idle running distance 300' is set in order to set the position of the same pulse as the precise origin detection position.

Therefore, in the case of C in FIG. 7, the next free running distance 300' is set to be longer than the temporary free running distance 300 so that the pulse 206 is detected in the next precision origin detection operation,
In the case of D, the next idle running distance 300' is set to be shorter than the temporary idle running distance 300 so that the pulse 205 is detected. Above A and B.

In cases C and D, the next idle running distance 300' is set to be shorter than the total moving distance from the rough origin detection position to the precise origin detection position by a distance that is greater than the error range 101 and smaller than the pulse interval. Assuming that the next free running distance is DO1, the total moving distance from the current coarse home detection position to the precise home detection position is Dt, the error range is DE, and the pulse interval is DC, these conditions must be satisfied: DC≧2XDE... ...(1)D
It is considered that o≧Dt −(DC−DH) (2).

As described above, in this embodiment, if the temporary idle running distance 300 interferes with the detection of the precise origin, in other words, the precise origin detection position may shift depending on the rough origin detection position, so the temporary idle running distance 300 is After correction, the next idle running distance 300' for the next origin detection operation is set and stored in the memory 11. The above-mentioned operation is performed by the idle running distance setting means as shown in step 508 in FIG. 5, or in other words, by the adjustment movement amount setting means.

In this way, by providing a setting means for setting the adjustment movement amount, and thereby setting the adjustment movement amount for the origin detection operation at the next startup every time the device is started, the apparatus of this embodiment can detect the coarse origin. No matter what the relative positional relationship between the detection error range and the monitor signal is, the same monitor signal can be detected as the precision origin every time the system waits for startup.

Due to the operation of this embodiment described above, the device of this embodiment can:
No matter what happens to the error range of the coarse origin and the position of the pulse in the origin detection operation, the same precise origin can be reliably detected every time the device is started.

Further, there is no need to adjust the relative position between the rough origin detection position and the precise origin detection position during machine design and assembly, and the work of designing and assembling the machine is simplified.

Furthermore, in this embodiment, by storing the total moving distance from the rough origin detection position to the precise origin detection position in the memory 11, deviations due to wear or deformation of the coupling between the moving part 3 and the drive mechanism 4 can be avoided. can be detected. For example, if the total distance traveled by the first origin detection operation after machine assembly is stored, coupling displacement can be detected by comparing this with the total distance traveled by the next origin detection operation.

Note that the rough origin detection in this embodiment is performed using the mechanical dock 6a.
The rough origin is detected by detecting the voltage drop across the resistor 95.96 due to an overcurrent flowing through the motor 1 when the mechanical stopper 6b comes into contact with the motor 1. There is.

In addition, in this embodiment, in the origin detection operation each time the position control machine waits for startup, a new empty running distance is set to be used in the next origin detection operation, but the origin point at the first startup after machine assembly is set. The idle running distance set in the detection operation may be used in the subsequent origin detection operation.

〔Effect of the invention〕

As is clear from the above description, the apparatus of the present invention performs an adjustment movement iiD within a coarse origin detection error range of 08 or more from the position of the moving member where the coarse origin detection signal is output.

The movable member is further moved from a position separated by a distance of 1,000 mL, and the position of the next monitor signal generated is detected as the precision origin.

Therefore, even if the monitor signal of the movement amount detection means is output within the rough origin detection error range DB, the detection position of the precision origin will not shift, and the same monitor signal will be detected as the precision origin. can do.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 3 shows the motor 1, coarse origin detection circuit 7, and motor drive circuit shown in FIG. 9, FIG. 4 is a block configuration diagram of the precision origin detection circuit 8 shown in FIG. 2, FIG. 5 is a flowchart of precision origin detection operation of one embodiment shown in FIG. 7 is a conceptual diagram showing the relationship between the coarse origin, the free running distance, and the precision origin. FIG. 8 is a conceptual diagram showing the relationship between the coarse origin and the precision origin according to the prior art. M...Position control machine, 1...Motor, 2...Incremental encoder, 3...Moving unit, 7...Rough origin detection circuit, 8...Precision origin detection circuit, 9... Motor drive circuit, 10... control circuit, 11... memory.

Claims (1)

[Scope of Claims] A moving member movably provided in a position control coordinate system; a drive source for moving the moving member; and outputting a monitor signal each time the moving member is moved by a constant DC distance. movement amount detection means; coarse origin detection means for detecting that the moving member is within the rough origin detection error range DE in the position control coordinate system and outputting a rough origin detection signal; a storage means for storing an adjustment movement amount D0 (D0≧DE) from the origin to the time when the coarse origin is moved by more than a detection error range DE; When the movable member is moved from the origin by the adjustment movement amount D0 stored in the storage means and then further moved and the next output monitor signal is detected, the movable member reaches the precision origin of the position control coordinate system. 1. An origin detection device for a position control machine, comprising: precision origin detection means for outputting a precision origin detection signal indicating that the origin is present.