JPH04245308A - Fault prediction device - Google Patents

Abstract

PURPOSE:To predict a fault by capturing a case wherein variation in operation state from a reference value increases gradually by a mechanism such as a robot and a manipulator. CONSTITUTION:The actuator, etc., is controlled to places the mechanism in specific operation, for example, without any load and the degree of speed variation at this time is measured. For the degree of speed variation, the variation width of a rotating speed signal and its variation quantity are measured. The measured values are compared with reference values in a normal state to predict a fault from how many times the permissible variation width is exceeded, the tendency of excess of the permissible variation width, and the permissible limit of acceleration.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for predicting failures in mechanisms such as robots and manipulators driven by motors.

0002

BACKGROUND OF THE INVENTION For example, when a robot or the like is used for a long period of time, the gears and the like that make up the drive force transmission system wear out, which affects its movement and control accuracy. In general, the effects described above cannot be easily confirmed from the outside, and the effect gradually increases without the operator knowing it, and eventually gears, etc. break, causing the robot to fail. It will suddenly stop. Therefore, the present invention has been devised in view of the above-mentioned circumstances, and is capable of detecting changes in the influence that gradually become larger as described above as an abnormality, and detecting changes in the influence that gradually become larger as described above, and detecting the change in the influence as an abnormality until the mechanism of a robot or the like becomes in a failure state and stops. The object of the present invention is to provide a failure prediction device that can predict failures in advance.

0003

[Means for Solving the Problems] In order to achieve the above object, the main means adopted by the present invention is a failure prediction device for a mechanism driven by an actuator, which controls the actuator. an operating means for causing the mechanism to operate in a predetermined manner; a memory means for storing a reference value representing a state when the mechanism operates normally; and an operating means for controlling the actuator by the operating means to cause the mechanism to operate in a prescribed manner. a measuring means for measuring the degree of speed fluctuation during the operation, and comparing the measured value by the measuring means with the reference value stored in the storage means, and based on the result, an abnormality occurs in the mechanism. This is a failure prediction device comprising a determination means for predictively determining whether or not.

0004

[Operation] In the failure prediction device according to the present invention, the actuator is controlled to cause the mechanism to operate in a predetermined manner, for example, in a no-load state, and the degree of speed fluctuation at this time is measured. The degree of this speed fluctuation is measured as the fluctuation range of the rotational speed signal and its slope (acceleration). Then, the measured value is compared with a reference value that represents the state when the above mechanism operates normally under no load, and based on the result,
It is predictively determined whether or not an abnormality will occur in the mechanism.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples embodying the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention. It should be noted that the following examples are examples of embodying the present invention, and are not intended to limit the technical scope of the present invention. Here, FIG. 1 is a flowchart showing a procedure for predictively determining whether or not an abnormality will occur in a robot, for example, in a failure prediction device according to an embodiment of the present invention, and FIG. Reference signal (A) and measurement signal (B) used
).

The failure prediction device according to this embodiment includes an operating means for controlling, for example, a servo motor to move each operating axis of the robot in one direction or both directions with no load, and an operating means that controls each operating axis of the robot in one direction or both directions with no load. a storage means for storing a waveform of a feedback signal of, for example, a rotational speed corresponding to a reference value representing a state of normal operation in a state of a measuring means for measuring the degree of speed fluctuation (for example, the width of speed fluctuation in a feedback signal of the motor's rotational speed, the acceleration representing the tendency of the fluctuation, or the number of times these values exceed a reference value); and the measuring means For example, a measured value such as a feedback signal of the rotational speed measured by the above-mentioned storage means is compared with a feedback signal of the rotational speed in a normal state which is the reference value stored in the storage means, and based on the result, the operation axis is and determining means for predictively determining whether or not an abnormality will occur.

[0007] In the apparatus of this embodiment, each of the above-mentioned means is constructed by software within a control device for controlling a robot equipped with the operating axis. The above-mentioned software that constructs this failure prediction device, for example, apart from the normal teaching/playback mode,
It is provided as a failure prediction check mode and is executed at appropriate intervals during normal work. By the way, when each operating axis of a robot is operated one by one in one direction, the rotational speed of the servo motor that drives the operating axis is normal, as shown in Figure 2 (A). The feedback signal of the rotational speed appears almost constant. However, if the gears that make up the driving force transmission system wear out and abnormalities begin to occur in this transmission system, then Fig. 2 (B)
As shown in FIG. 2, for each rotation of the servo motor, a speed fluctuation phenomenon (uneven rotation) occurs, for example, once. At this time, vibrations also occur in the robot.

[0008] Due to the above-mentioned abnormalities, the robot will eventually fail and have to stop, but in the device of this embodiment, this failure prediction is carried out in the following procedure. That is, as shown in Fig. 1, in the failure prediction check mode, each operating axis is sequentially driven by a servo motor in one direction or both directions with no load, and a check is performed for each operating axis ( Step S1). That is, during the operation of each operating axis, the degree of variation in the rotational speed, such as the number of times the permissible speed fluctuation range is exceeded or the number of times the permissible acceleration limit is exceeded, is counted in the feedback signal of the rotational speed of the servo motor. The reference value in this case is determined in advance based on the value detected when each operating axis is operated in an ideal state, and is stored in the memory in advance.

[0009] In this case, instead of counting the number of times as described above, it is simply checked whether the permissible speed fluctuation range has been exceeded or not.
Alternatively, each motion axis may be checked depending on whether the allowable acceleration limit has been exceeded. A check is performed on each operating axis as described above, and it is determined whether the value exceeds the reference value (step S2). If it is determined that the value exceeds the reference value, a failure will occur in that operating axis. Since it is clear that this occurs, an error is displayed for that axis of motion (step S3).
. The failure prediction device according to this embodiment is configured as described above.

[0010] Therefore, by using the failure prediction device, it is possible to detect in advance an abnormal situation in which the robot breaks down and suddenly stops, and maintenance can be carried out as appropriate. As mentioned above, since maintenance can be performed on robots before they break down, it is possible to minimize damage in terms of material, time, or cost, which can greatly contribute to improving the operating rate of production lines. It is.

[0011]

[Effects of the Invention] As described above, the present invention is a failure prediction device for a mechanism driven by an actuator. a storage means for storing a reference value representing a state when the actuator is operated; a measuring means for measuring the degree of speed fluctuation when the actuator is controlled by the operating means to operate the mechanism in a predetermined manner; and a determination means for comparing the measured value with the reference value stored in the storage means and predictingly determining whether or not an abnormality occurs in the mechanism based on the result. By using this failure prediction device, it is possible to avoid abnormal situations where a mechanism such as a robot suddenly stops due to a failure, and for example, it can be used to improve the operating rate on a production line. It can make a big contribution.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing a procedure for predictively determining whether or not an abnormality will occur in a robot, for example, using a failure prediction device according to an embodiment of the present invention.

FIG. 2 is a graph showing a reference signal (A) and a measurement signal (B) used in the failure prediction device.

Claims (1)

[Claims] 1. A failure prediction device for a mechanism driven by an actuator, comprising operating means for controlling the actuator to cause the mechanism to operate in a predetermined manner, and a reference value representing a state when the mechanism operates normally. a storage means for storing, a measuring means for measuring the degree of speed fluctuation when the actuator is controlled by the operating means to operate the mechanism in a predetermined manner, and a measured value measured by the measuring means and the storing means are stored. A failure prediction device comprising: a determination means for comparing the stored reference value with the reference value and predictingly determining whether or not an abnormality will occur in the mechanism based on the result.