JPH10122897A - Generating method of judgment waveform - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a generating method in which an upper-limit judgment waveform is generated so as not to mistake a normal operation for an abnormal operation by a method in which, when a prescribed interval is applied to the arbitrary position of a reference waveform, a maximum value within the prescribed interval is used as its position, the central position of the prescribed interval is used as its position and a position to which the prescribed interval is applied is changed sequentially. SOLUTION: A current which flows to a motor 1 is detected by a current detector 2, and an analog signal which indicates the envelope of the current flowing to the motor 1 is supplied to the input terminal 4 of a waveform monitoring device 3. The current change waveform of the motor 1 in an operating state is input while it is being sampled by a CPU 7 via a filter 5 and an A/D conversion circuit 6 at a prescribed interval of one cycle portion. The waveform is compared respectively with an upper-limit judgment waveform and a lower-limit judgment waveform which are stored in a memory 8. When the input waveform is larger than the upper-limit judgment waveform or smaller than the lower-limit judgment waveform, it is outside a tolerance. As a result, an output device 12 is operated via an output interface 11, and a warning operation is performed in such a way that a lamp is blinked or that a buzzer is sounded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveform monitoring method for determining whether a signal waveform falls within a predetermined allowable range, and more particularly, to generating a determination waveform serving as a reference for determination. On how to do it.

[0002]

2. Description of the Related Art For example, in an automatic machine tool, various processes are performed on a work as a work process proceeds. For example, in a drilling device, a drill is connected to a motor and automatically drilled as needed to sequentially drill a predetermined portion of a workpiece. At this time, the current flowing through the motor changes depending on the processing location of the work or the type of drill, but in the same work process for the same type of work, the waveform of the change in current in each work process is the same. Here, the waveform of the current change means a waveform indicating the envelope of the current.

[0003] Therefore, it is performed to detect the current flowing through the motor and compare the waveform of the change of the detected current with a reference waveform to determine whether the machine tool is operating normally. That is, an upper-limit determination waveform and a lower-limit determination waveform are generated around the reference waveform, and it is determined whether or not a change in the detection signal is between the upper-limit determination waveform and the lower-limit determination waveform, that is, whether the waveform is within an allowable range. If it is out of the allowable range, it is determined that the operation of the machine is abnormal and an alarm is issued.

In order to determine the quality of the change in the detection signal, it is necessary to first create a reference waveform, and then form an upper limit determination waveform and a lower limit determination waveform from the reference waveform.

FIG. 10 is an explanatory diagram for explaining a conventional judgment waveform generation method. In a conventional waveform monitoring method, a machine is operated in a normal state, and a signal generated at that time is stored in a storage device as a reference waveform R. next,
The reference waveform R is vertically moved upward by a predetermined amount and stored as an upper limit determination waveform JMAX, and the reference waveform R is vertically moved downward by a predetermined amount and stored as a lower limit determination waveform JMIN. Then, the waveform of the detection signal is the upper limit determination waveform J
If the signal does not exist between MAX and the lower limit determination waveform JMIN, it is determined that an abnormality has occurred.

[0006]

However, as described above, when the reference waveform R is moved up and down in the vertical direction to create the upper limit judgment waveform JMAX and the lower limit judgment waveform JMIN, there is a margin in the amplitude direction. However, at the rising and falling portions of the signal, there is no margin in the time axis direction, so that even if the waveform of the change of the detection signal slightly changes in the time axis direction, there is no problem in practice. However, there is a disadvantage that a warning is issued because the operation is regarded as an abnormal operation.

Therefore, the present invention creates upper and lower limit determination waveforms having a margin in the time axis direction even at the rising portion and the falling portion of a signal so that a normal operation is not erroneously regarded as an abnormal operation. That is the task.

[0008]

According to the present invention, when a specified interval having a predetermined width is set with respect to a reference waveform, and when the specified interval is applied to an arbitrary position of the reference waveform, a maximum value within the specified interval is obtained. The value is set as the value, the position of the center of the specified interval is set as the position, and the position to which the specified interval is applied is sequentially changed to generate the upper limit determination waveform.

Further, according to the present invention, when a specified interval having a predetermined width is set with respect to a reference waveform, and the specified interval is applied to an arbitrary position of the reference waveform, the minimum value within the specified interval is set to the value. And the center position of the specified interval is defined as the position, and the lower limit determination waveform is generated by sequentially changing the position to which the specified interval is applied.

[0010]

FIG. 1 is a block diagram showing an example of a waveform monitoring apparatus to which a judgment waveform generation method according to the present invention is applied.

The current flowing through the motor 1 is detected by a current detector 2, and an analog signal indicating the envelope of the current flowing through the motor 1 is supplied to an input terminal 4 of a waveform monitoring device 3.
The signal supplied to the input terminal is converted into a digital signal by an A / D conversion circuit 6 after noise is removed by a filter 5. The value of this digital signal is sequentially read at predetermined time intervals by the CPU 7 and stored in the memory 8. Various instructions are input to the CPU 7 from the input device 10 via the input interface 9. Although details will be described later, the CPU 7 first creates upper and lower limit determination waveforms based on the detection signal supplied to the input terminal 4,
Next, the waveform of the detection signal is monitored based on the created upper and lower limit determination waveforms. If the waveform of the detection signal does not exist between the upper and lower limit determination waveforms, it is considered that an abnormality has occurred. An alarm signal is supplied to the output device 12 via the output interface 11 to perform a warning operation such as blinking of a lamp, sounding of a buzzer, or display of a warning character.

The operation of the above-described waveform monitoring device will be described below step by step.

<Generation of Reference Waveform> FIG. 2 is a flowchart for explaining a reference waveform generation operation in the waveform monitoring apparatus shown in FIG.

A waveform of a change in current of the motor 1 operating in a normal state is input while sampling one cycle at predetermined intervals (step 101), and the maximum value at each sampling time is stored (step 102). Then, the minimum value at each sample time is stored (step 103). Step 1
The process from 01 to 103 is repeated for a predetermined cycle (step 104). By this processing, as shown in FIG. 3, a waveform RMAX indicating the maximum value of the reference waveform and a waveform RMI indicating the minimum value of the reference waveform during the normal operation.
N is required.

<Generation of Upper and Lower Limit Waveforms> FIG. 4 is a flowchart for explaining the operation of generating the upper and lower limit waveforms in the waveform monitoring apparatus shown in FIG.

First, from the waveform RMAX indicating the maximum value of the reference waveform in the normal state operation shown in FIG. 3, an upper limit lateral movement waveform is generated in the following procedure.

As shown in FIG. 5 (a), when a specified interval P having a certain width is set and the specified interval P is applied to an arbitrary position of the maximum reference waveform RMAX, the maximum value within the specified interval P is obtained. The value is set as the value, and the position of the center of the specified interval P is set as the position.

For example, in the example shown in FIG. 5A, the prescribed interval P is equally divided into four regions by five boundary lines, and the reference waveform is represented by y = f (x). I do. The x coordinate of each boundary line is n-2, n-1, n, n + 1, n +
2 and the corresponding y coordinate is f (n−
2), f (n-1), f (n), f (n + 1), f (n
+2). Here, the maximum value (y (n + 2) in the example of FIG. 5A) of the above five y values is represented by x
= Plotted at position n. Note that the number of boundary lines is an odd number of 3 or more.

By performing the above-described processing over one cycle of the maximum reference waveform RMAX while sequentially changing the position to which the specified interval P is applied, the upper limit lateral movement as shown by the dotted line in FIG. A waveform RMAXH is obtained (Step 201).

Next, the calculation of a · f (x) + b is performed on the upper-limit lateral movement waveform RMAXH to obtain an upper-limit determination waveform JMAX as shown by a dotted line in FIG. 6B (step 202). However, a ≧ 1 and b ≧ 0.

Next, as shown in FIG. 5B, when a specified interval P is applied to an arbitrary position of the minimum reference waveform RMIN, the minimum value within the specified interval P is set to the value, and the specified interval P is set. Let the position of the center of P be that position.

By performing this processing over one cycle of the minimum reference waveform RMIN while sequentially changing the position to which the specified interval P is applied, the lower limit horizontal movement waveform as shown by the broken line in FIG. RMINH is obtained (step 203).

Next, the calculation of cf (x) -d is performed on the lower limit lateral movement waveform RMINH to obtain a lower limit determination waveform JMIN as shown by a broken line in FIG. 6D (step 204). . However, c ≦ 1, d ≧ 0.

By the above-described processing, as shown in FIG. 7, it is possible to generate an upper limit judgment waveform JMAX and a lower limit judgment waveform JMIN having a margin in both the amplitude direction and the time axis direction with respect to the reference waveform R. In FIG. 7, the maximum reference waveform RMAX and the minimum reference waveform RMIN are shown at the same position.

Note that the specified interval P cannot be secured for the first and last portions of the waveform, so that the above-described algorithm cannot be applied. Therefore, as shown in FIG. 8, in a range where the specified interval P cannot be ensured, the value of the full scale is set when the upper limit waveform is generated.
That is, the maximum value of the inputtable voltage range is set as the upper limit waveform. In generating the lower limit waveform, the minimum value of the inputtable voltage range is used as the lower limit waveform.

The upper limit determination waveform J created as described above
MAX and the lower limit determination waveform JMIN are stored in the memory 8.

<Waveform Monitoring> FIG. 9 is a flowchart for explaining the waveform monitoring operation in the waveform monitoring apparatus shown in FIG. First, the waveform of the change in the current of the motor 1 in the operating state is passed through the filter 5 and the A / D conversion circuit 6,
An input is made while sampling at predetermined intervals for one cycle by the CPU 7 (step 301). Then, the input waveform is converted to the upper limit determination waveform JMA stored in the memory 8.
X and the lower limit determination waveform JMIN are compared (steps 302 and 304). Input waveform is upper limit judgment waveform JMAX
If the value is larger than the lower limit determination waveform JMIN or smaller than the lower limit determination waveform JMIN, the output device 12 is operated via the output interface 11 and blinks a lamp, sounds a buzzer, and displays a warning character. Perform a warning action.

At the time of this waveform monitoring, as shown in FIG. 4, the waveform monitoring is performed using the upper limit judgment waveform JMAX and the lower limit judgment waveform JMIN, which have a margin in the time axis direction at the rising portion and the falling portion of the signal. Therefore, the normal operation is not mistakenly regarded as an abnormal operation.

[0029]

As described above, it is possible to form an upper limit judgment waveform and a lower limit judgment waveform having a margin in the time axis direction even at the rising portion and the falling portion of the signal. The normal operation is not mistakenly regarded as an abnormal operation.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a waveform monitoring device to which a determination waveform generation method according to the present invention is applied.

FIG. 2 is a flowchart for explaining a reference waveform generation operation in the waveform monitoring device shown in FIG. 1;

FIG. 3 is a waveform RMAX indicating the maximum value of the reference waveform and a waveform RMI indicating the minimum value of the reference waveform during normal operation.
It is explanatory drawing which shows N.

FIG. 4 is a flowchart for explaining an upper limit and lower limit waveform generation operation in the waveform monitoring device shown in FIG. 1;

FIG. 5 is an explanatory diagram showing a procedure for generating upper and lower limit horizontal movement waveforms.

FIG. 6 is an explanatory diagram showing a procedure for generating upper and lower limit determination waveforms.

FIG. 7 is an explanatory diagram showing a relationship between an upper limit determination waveform JMAX and a lower limit determination waveform JMIN with respect to a reference waveform R.

FIG. 8 is an upper limit determination waveform JM in the first part of the waveform.
FIG. 9 is an explanatory diagram showing an AX and a lower limit determination waveform JMIN.

9 is a flowchart for explaining a waveform monitoring operation in the waveform monitoring device shown in FIG.

FIG. 10 is an explanatory diagram for describing a conventional determination waveform generation method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Motor, 2 ... Current detector, 3 ... Waveform monitoring device, 4 ...
Input terminal, 5: filter, 6: A / D conversion circuit, 7: C
PU, 8 ... memory, 9 ... input interface, 10 ...
Input device, 11 output interface, 12 output device

Claims (4)

[Claims] When a specified interval having a predetermined width is set with respect to a reference waveform, and the specified interval is applied to an arbitrary position of the reference waveform, a maximum value within the specified interval is set as the value, and A method of generating a determination waveform, wherein a center position of a specified interval is set as the position, and an upper limit determination waveform is generated by sequentially changing positions to which the specified interval is applied. 2. The method according to claim 1, wherein the maximum value of the reference waveform is set to the maximum value of the inputtable voltage range at an initial portion and an end point of the reference waveform. 3. When a specified interval having a predetermined width is set with respect to a reference waveform, and when the specified interval is applied to an arbitrary position of the reference waveform, the minimum value within the specified interval is set as the value, and A determination waveform generating method, wherein a lower limit determination waveform is generated by sequentially changing a position to which the specified interval is applied, with a center position of the specified interval as the position. 4. The determination waveform generation method according to claim 3, wherein a minimum value of the inputtable voltage range is used as a lower limit determination waveform at a first portion and an end point of the reference waveform.