JPH03100411A - Abnormality deciding device of position detector - Google Patents

Abstract

PURPOSE:To execute the abnormality decision corresponding to positioning with high accuracy, and also, to prevent the abnormality decision from being executed oversensitively by changing an allowable error in accordance with a moving state of a position detecting object. CONSTITUTION:An allowable error changing means M5 changes an allowable error in accordance with a moving state such as whether a position detecting object M1 is stopping or moving, etc., an abnormality deciding means M4 executes an abnormality decision basing on the allowable error corresponding to this moving state. Also, at the time of executing the abnormality decision, it is allowable to convert the present position of the object M1 from a detection value of a relative position variation quantity detecting means M3 and to compare it with a detection value of an absolute position detecting means M3, and it is also allowable to convert the detection value of the means M3 to the absolute value variation quantity and to compare it with the detection value of the means 2. Moreover, if only both the detection values can be compared, use of any method for conversion and comparison is allowable.

Description

[Detailed description of the invention] Precise [Industrial application field] The present invention (part 1) relates to an abnormality determination device for a position detector, in which the difference in position or position change amount determined by two detection means exceeds a permissible error. The present invention relates to a device that determines an abnormality when a case occurs.

[Prior Art] For example, Japanese Patent Laid-Open No. 54-40374 is known as a device for determining abnormality in a position detector.

The device described in this publication (tomo) has an incremental position detector that detects the displacement of a moving table of a machine tool and an absolute position detector that detects the absolute position of the moving table that are installed side by side. If the difference between the integrated value and the detected value of the absolute type position detector exceeds the allowable error (top). Tomo: Based on the accuracy ±α necessary for machine tool control, add the measurement error Δα caused by the detection timing shift and phase shift of each detector while the table is moving, and calculate the value increase (α + Δα). [Problem to be solved by the invention] However, it is necessary to maintain accuracy ±α when the moving table is stopped, and the conventional technology ( Friend: In order to prevent sensitive judgments during movement (Friend: it is necessary to sacrifice this accuracy ±α), it is therefore impossible to detect judgments of 1 or higher in machine tools at an early stage. Anomaly determination device for position detector
The purpose is not to overly judge abnormalities.

[Means for Solving the Problems] An abnormality determination device for a position detector according to the present invention (as illustrated in FIG. relative position change amount detection means M2; and absolute position detection means M for detecting the absolute position of the position detection object M with a resolution coarser than that of the relative position change amount detection means M2.
3, and each of the detection means M2. A position detector comprising an abnormality determination means M4 that converts and compares the amount of change in relative position and absolute position detected by M3, and determines that there is an abnormality if the result of the conversion and comparison exceeds a predetermined tolerance. The abnormality determination device may include a tolerance changing means M5 for changing the tolerance according to the moving speed of the position detection target object M or a moving state such as whether it is stopped or moving. Features.

[Operation] In the abnormality determination device for a position detector of the present invention (table tolerance changing means M5 changes the moving speed of the position detection object M1, whether the position detection object M1 is stopped or moving, etc.) The allowable error is changed according to the moving state of the motor, and the abnormality determining means M4 executes abnormality determination based on the allowable error corresponding to the moving state.

In abnormality determination], the current position of the position detection object M1 may be converted from the detection value of the relative position change amount detection means M2 and compared with the detection value of the absolute position detection means M3;
The detected value of the absolute position detecting means M3 may be converted into an absolute value change amount and compared with the detected value of the relative position change amount detecting means M2. Any method of conversion and comparison may be used as long as the ground rain detection values can be compared.

[Examples] Next 1'-Examples embodying the present invention will be described in detail based on the drawings.

FIG. 2 shows a schematic configuration of an embodiment in which the present invention is applied to a moving mechanism for a work table 1 of a numerically controlled machine tool. In addition,
For simplicity, a case is shown in which the work table 1 moves along one axis.

This machine tool includes a work table 1, a feed screw 3 screwed onto the work table 1, a motor 5 that drives the feed screw 3 in forward and reverse rotation, and an encoder 7 directly connected to the rotating shaft 6 of the motor 5. A moving mechanism is constructed centering on a numerical control device 11 which receives a detection signal from an encoder 7 and outputs a drive signal to the motor 5 via a drive device 9.

Encoder 7 (as shown in Fig. 3 above, includes an incremental signal generating section 15 consisting of slits arranged at equal intervals on the outer circumference of a disk 13, and a predetermined pattern on the inner circumferential side of the incremental signal generating section 15). An absolute signal generating section which generates an 11-bit absolute signal by a combination of the slits arranged in [7] is provided, and a detection signal is output by a light source and a photosensor (both not shown) arranged at a predetermined position. Incidentally, Table 1 shows the resolution of the incremental signal generator 15. Absolute signal generator 17
The resolution is set higher than that of the absolute signal generator]7, and the position can be detected eight times more precisely than the absolute signal generator]7.

Numerical control device 1] (includes a drive control circuit 19, a comparison/judgment circuit 21, and a drive control circuit 9. A signal Sl detected by an incremental signal generator 15 (hereinafter referred to as an inflation signal) is input to the drive control circuit 9. Comparison/judgment circuit 21
A signal SA (hereinafter referred to as an absolute signal) detected by the absolute signal generating section 17 is inputted via the absolute position detection device 23.

The drive control circuit 19 integrates the input inflation signal S1 to obtain the current position P1 of the work table 1, and outputs a control signal to the drive device 9 based on this current position P1. The current position P1 is sent to the comparison/judgment circuit 21. On the other hand, the absolute position detection device 23
Table 1 An absolute position PA having an accuracy of 178 with respect to the current position P1 of the work table 1 is determined from the input absolute signal SA and the number of rotations of the encoder 7. In addition,
Absolute position detection device 23 (friend) Absolute position PA even after power is cut off
The information is backed up to be retained. The current position P1 and the absolute position PA thus determined are input to the comparison/judgment circuit 21. As shown in FIG. 4, an abnormality determination for the position detection is executed.

One abnormality determination process: Executed by interruption every predetermined time.

When the process is started, the current position P1 and absolute position PA of the work table 1 determined as described above are read (steps Sl, S2; hereinafter, the steps are simply referred to as Sl, 32, etc.).

Next 1: Determine whether the motor 5 is being driven (S
3). Even if the motor 5 is driving (Dai), the tolerance Q in the following abnormality determination is the precision of the control position required for processing by the machine tool, the deviation of the detection timing from each signal generator 15, 17, and the position calculation timing. A value Ql is set in consideration of the deviation, etc. of the motor 5 (S4).
When the machine is not driven, the allowable error Q is a value Q2 determined based on the accuracy of the control position of the machine.
is set (S5). Note that the value Q1 is a larger numerical value than the value Q2.

Next, the absolute value IPI-FAI of the difference between the current position P1 and the absolute position PA is determined as the error R between the detected value by the incremental signal generating section 15 and the detected value by the absolute signal generating section 17 (S6), and this error is It is determined whether R exceeds the allowable error Q (S7). When the error R exceeds the allowable error Q (upper incremental signal generator 1
The detected value No. 5 is determined to be abnormal and an error signal SEP is generated (S8).

The error signal 5ER1 is sent to the alarm device 25 connected to the comparison/judgment circuit 21 and appears as an alarm such as a buzzer sound or a flashing signal. The error signal 5ERf is also sent to the drive control circuit 19. In response to this, the drive control circuit 19
stops the drive of the motor 5.

As described above, 1: In this embodiment, the drive control of the motor 5 is executed based on the relative movement amount of the work table 1 detected by the high-resolution incremental signal generator 15, and the high-precision positioning is performed. However, the detection signal of the incremental signal generator 15 may be disturbed due to some reason such as the influence of noise or the loss of the detection signal, and the actual position ( If the error R between the absolute position PA (corresponding to the absolute position PA) and the control position (corresponding to the current position P1) exceeds the allowable error Q, it is determined to be an abnormality, and the motor 5 is immediately stopped and work is performed by a buzzer sound, flashing signal, etc. inform the person.

As a result, according to the present embodiment (f), by using the detection signal from the highly reliable absolute signal generating section 17, the reliability problem of the incremental signal generating section 15 can be solved and the position control can be performed with high precision. In addition, a large value Q1 is set as an allowable error while the motor 5 is being driven, and the difference in the detection timing between the inflation signal S1 and the absolute signal SA and the calculation timing of the current position P1 and absolute position PA can be avoided. This prevents the error signal SEP from being generated too sensitively based on the misalignment.
is stopped (above) The allowable error Q is set to a small value Q2 to correspond to the accuracy truly required for control.

From this, it is possible to prevent the error signal SEP from being generated too sensitively without sacrificing the accuracy of the control position when the motor 5 is stopped, and it is possible to perform optimal abnormality determination for the position detector. , it is possible to detect malfunctions at an early stage.

Furthermore, in this embodiment, since both the inflation signal S1 and the absolute signal SA can be obtained from the slits provided in the - discs 13, the incremental position detector and the absolute position detector can be used. Unlike the case where these are provided separately, there is no need to take into account errors based on the relationship between the mounting positions, and therefore extremely reliable abnormality determination can be performed.

In addition, although the example has been explained for convenience in a work table that moves in one axis direction, it can also be applied to a work table that moves in the X-orbit or Y-axis direction, and furthermore, it can be applied to a work table that moves in the X-orbit or Y-axis direction. Similar effects can be obtained with a similar configuration.

Further, in the embodiment, the allowable error is set to be large or small depending on whether or not the motor 5 is being driven, but it may be set more finely depending on the driving speed of the motor 5. In addition, the abnormality determination may not be performed while the motor is being driven; in this case, this is equivalent to a configuration in which the allowable error Q is set to infinity.

Further 1: In the embodiment, the current position P1 and the absolute position P^ are compared and determined, but the amount of change in the absolute position is calculated from the absolute signal SA and directly compared with the inflation signal S1.
It is also possible to have a configuration in which the determination is made.

In addition, in this embodiment, the abnormality determination is performed using the absolute value l PI −PA of the difference between the current position P1 and the absolute position PA. 〇a~+ob, -Qc while motor is driving
The allowable error may be set according to the direction of deviation, such as −Qd.

Although the present invention has been described in detail above, the present invention is not limited thereto and may be modified in various ways without departing from the gist thereof, such as a configuration in which a resolver is used as the l'L incremental position detector. Can be adopted.

l Hole base 41 As explained above 1: According to the present invention (subsection) Since the configuration is adopted in which the tolerance is changed according to the moving state of the object to be detected, it is possible to perform control in a stopped state where high accuracy is originally desired. Despite not sacrificing positional accuracy, oversensitive abnormality judgment is not performed.As a result, abnormality judgment of the position detector can be performed optimally, and malfunctions can be detected early. It is possible to do so.

[Brief explanation of drawings]

FIG. 1 is a block doctor illustrating the configuration of the present invention. FIG. 2 is a block doctor showing a schematic configuration of an embodiment. FIG. 3 is a front doctor showing the configuration of an encoder used in the embodiment. FIG. 4 is an example of abnormality determination processing. It is a flowchart which shows. 21...Comparison/judgment circuit 23...Absolute position detection device 25...Alarm device

Claims (1)

[Claims] 1. Relative position change amount detection means for detecting the amount of change in the relative position of a moving object to be detected; The absolute position detection means for detecting the position is converted and compared with the amount of change in relative position and the absolute position detected by each of the detection means, and if the result of the conversion and comparison exceeds a predetermined tolerance, it is abnormal. An abnormality determination device for a position detector, comprising: an abnormality determination means for determining that the permissible error is changed according to a moving speed of the position detection target or a moving state such as whether it is stopped or moving. 1. An abnormality determination device for a position detector, comprising a tolerance changing means.