JP2000141275A - Life testing method and device for industrial robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely test the life of a bearing of an industrial robot. SOLUTION: An electric current component ILh for longevity computation required for measurement of longevity of a bearing is extracted and found by detecting a load electric current IM of a motor for each of shafts of an industrial robot. Consequently, the electric current component ILh is found by finding a first electric current component 11 for rotation of a rotating part of a motor 2 itself and a second electric current component 12 for movement of a power transmission part by detecting angular acceleration wa of an output shaft 15 of the motor 2 and using this angular acceleration wa and deducting their sum (=11+12) from the load electric current IM. Torque working on the bearing is found by computing it from this electric current component ILh, a bearing load roughly in proportion to this torque is computed, rotational speed N of a shaft supported by the bearing is detected, and consequently, fatigue life Lh of the bearing corresponding to the cube of the electric current component ILh and rotational speed (n) is computed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring the life of components such as bearings in an industrial robot in which a plurality of axes are driven by motors.

[0002]

2. Description of the Related Art For example, industrial robots performing operations such as spot welding are required to have high reliability and to shorten the recovery time in the event of a failure. In the prior art, an hour meter is used to measure the cumulative power-on time of the control power supply of the industrial robot using the power meter, and based on the cumulative power-on time, maintenance such as replacement of components such as bearings is performed, and a failure is performed. It manages when it occurs.

In the prior art using the hour meter, it is impossible to quantitatively measure the usage history of the industrial robot, and therefore, it is necessary to replace parts during maintenance of the industrial robot with a high safety factor. Therefore, the cost is increased. In addition, it is difficult to determine the cause of a failure at the time of a sudden failure, and therefore it is difficult to take measures to prevent the recurrence of the failure, and it is difficult to maintain quantitative information for improving the reliability of the equipment.

Another prior art is US Pat. No. 2,535,366. In this prior art, a load current of a motor driving an axis of an industrial robot is detected, and a root-mean-square value thereof is calculated.
The square mean value is compared with the quantitative current and the ratio is output and displayed. The operator checks the ratio to confirm the appropriateness of the operation capability of the motor, and thereby corrects the robot operation program so that the operation of the joint axis can fully use the capability.

In this prior art, judging the appropriateness of the operating performance of the motor based on the root-mean-square value of the load current is suitable for evaluating the heat generation of the motor. However, it is not possible to evaluate the load condition of the bearing, which is one of the main life factors of the mechanical part of the industrial robot.

Further, in this prior art, since there is no function of calculating the life of components such as bearings, it is necessary for inspection and maintenance of components such as bearings of industrial robots, and for preventive maintenance of failures such as determination of parts replacement time. However, this prior art is not available.

The prior art for calculating the life of a driving system component such as a bearing of an industrial robot is disclosed in Japanese Utility Model Laid-Open No. 5-37490.
It is. In this prior art, when the average load sample value Fi is defined as Ki = torque constant from the current value Ii and the average rotation speed Ni sampled at a constant cycle, Fi = Ki ·
By using Ii, the average load F is calculated, and the estimated life of the components of the drive system is calculated. That is, this prior art discloses a method of calculating the life of a bearing from a time-varying force and a rotational speed. The above-described average load sample value Fi merely determines the motor torque.
Therefore, if a load acting on the bearing of the robot arm, which is actually a problem, is determined based on such an average load sample value Fi, only a very rough evaluation can be made.

The reason is that the motor torque includes the inertia torque of the motor itself and the mechanical element to be evaluated, for example, the drive system up to the bearing. Moreover, in industrial robots, acceleration and deceleration movements occupy most of the operation time in most cases. As described above, since the robot is a machine whose acceleration and deceleration are intense, it is inaccurate to evaluate the life of the bearing under actual use conditions based only on the current value Ii of the motor.

Assuming that the load estimation is calculated to be 30% excessive in order to avoid failure due to life, the bearing life becomes
Since the load is inversely proportional to the cube of the load or the cube of the load, the life is estimated to be shorter than half of the actual life.
Therefore, the user greatly mistakes the truly required maintenance period, which is not practical.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus for accurately measuring the life of components such as bearings constituting an industrial robot.

[0011]

SUMMARY OF THE INVENTION The present invention detects a load current IM of a motor for driving an axis of an industrial robot having a plurality of axes, and comprises, among the load current IM, a component constituting the industrial robot. Is calculated by calculating the sum of the current component IS corresponding to the static force FS acting on the current and the current component I3 corresponding to the dynamic force FD3 transmitted from the above-mentioned components. And calculating a calculated value related to the cube of the life calculating current component ILh, and calculating a life of a constituent element of the industrial robot based on the calculated value. It is a measuring method.

The present invention makes it possible to accurately measure the life of a component constituting an industrial robot, for example, by calculating the load actually acting on a bearing with high accuracy. To enable highly accurate estimation of life, the motor torque calculated based on the load current of the motor is subtracted from the motor itself and the inertia torque from the motor to the bearing that is the component to be evaluated. It is necessary to calculate the torque. Since the bearing life is inversely proportional to the cube of the load or the power of 10/3, if the accuracy of the load estimation is poor, the life estimation becomes a significantly different value and has no practical significance.

[0013] Of the load current of the motor, the motor current component related to the force acting on the bearing is a static force F
Only the current component IS corresponding to S and the current component I3 corresponding to the dynamic force FD3 subsequently transmitted from the bearing, and therefore the load on the bearing is calculated from the motor to the bearing. Of the driving system of the drive system, that is, the reduction ratio, the lever ratio, etc.
This improves the accuracy of the load estimation of the bearing. The same applies to the components other than the bearing.

According to the present invention, each axis of an industrial robot having a plurality of axes such as six axes is driven by a motor as an electric motor, and corresponds to a static force FS of the detected load current I. Only the sum of the current component IS and the current component I3 corresponding to the dynamic force FD3 subsequently transmitted from the component is calculated, and the sum is calculated as the life calculation current component ILh
Then, a calculation value related to the cube of the life calculation current component ILh is calculated, thereby calculating the life of a component such as a bearing. The calculated value is a life component current component IL.
The value of the cube of h or a value approximating the cube of the life component ILh, for example, 1 of the life component ILh
It may be a value of 0/3 power. The calculated value may be the life Lh of the bearing or the like, the ratio η or (1−η), the time W2, or the like, as described later, and includes other values. That is, the life of the bearing may be the fatigue life Lh, or may be a ratio η, which is an actual operation time W1 / life calculation time WL described later, and is (1-η). And the remaining time WL-W1 may be included, and may include other life-related values. The components may be bearings as described above, but also include gears, links, arms, shafts and the like.

Further, the present invention calculates a bearing load F corresponding to the calculated value, detects a rotation speed N of a shaft supported by the bearing, and calculates the calculated bearing load F, the rotation speed N, and the bearing speed. Bearing life Lh based on the rated load C of
Is calculated.

According to the present invention, the life Lh of the bearing can be obtained by calculation based on the bearing load F, the rotation speed N, and the rated load C. The rotational speed N of the shaft supported by the bearing may be determined by directly detecting the rotational speed N of the supported shaft. However, the rotational speed of the output shaft of the motor is determined, and the rotational speed of the output shaft is determined. The rotation speed N of the supported shaft may be obtained by, for example, multiplying the rotation speed of the output shaft by a proportional constant.

The present invention also measures the operating time ti of each of a plurality of types of operating states of an industrial robot, calculates an average speed Nm for each operating state, and calculates the average speed Nm obtained by the calculation. Is used to calculate the average value Fm of the fluctuating bearing load to calculate the life Lh of the bearing.

According to the present invention, when a plurality of types of operating conditions, for example, operating conditions change, or a plurality of robot operation programs change, an average value Fm of the fluctuating bearing load is calculated, and thereby the bearing load is calculated. The life Lh can be calculated.

Further, according to the present invention, the angular acceleration ωa of the output shaft of the motor is detected, and the first current component I1 necessary for rotating the rotating portion including the output shaft of the motor itself is detected using the angular acceleration ωa. The second current component I2 required to move the power transmission from the output shaft of the motor to said components.
(= I1 + I2), and the thus obtained first
The current component for life calculation ILh is obtained by subtracting the sum of the first and second current components I1 and I2 from the load current IM of the motor.

According to the present invention, the load current IM that can be measured by the motor includes the current component IS corresponding to the static force FS constituting the life calculation current component ILh, and the load component IM transmitted from the above components. Not only the sum with the current component I3 corresponding to the dynamic force FD3, but also the first and second current components I3
1, I2 are also included, and the life component current component IL
h alone cannot be measured separately from the first and second current components I1 and I2. The sum of the first and second current components I1 and I2 (= I1 + I2) accounts for a large proportion of the entire load current IM of the motor, for example, 30 to 50.
Account for%. In the present invention, the first and second current components I1 and I2 are calculated based on the angular acceleration ωa of the output shaft of the motor. The angular acceleration ωa of the output shaft of the motor can be obtained by calculating the time change rate of the rotation speed of the output shaft of the motor. In this way it is easily possible to increase the accuracy of the momentary force calculation itself.

The present invention also provides a current detecting means for detecting a load current of a motor for driving an axis of an industrial robot having a plurality of axes, and a current component calculating means for calculating a life. A current component IS corresponding to a static force FS acting on components constituting the industrial robot;
Means for calculating a life component current component ILh by calculating the sum of a current component I3 corresponding to a dynamic force FD3 transmitted from the component and thereafter, and a life calculation current component A current calculating means responsive to an output of the calculating means for calculating a calculated value related to the cube of the life calculating current component ILh; A life measuring device for an industrial robot, comprising: a life calculating means for calculating; and a notifying means for displaying or outputting acoustically the life calculated by the life calculating means.

According to the present invention, of the load current of the motor detected by the current detecting means, a life calculation current component ILh is calculated and obtained, and the life calculation current component ILh is calculated.
The calculated value related to the cube of is calculated by the current calculating means, whereby the life of the components such as the bearings constituting the industrial robot is calculated by the life calculating means, and is visually displayed on a cathode ray tube or a liquid crystal display panel. Means or a notifying means comprising a speaker for outputting a sound signal generated by the sound synthesizing circuit.

Further, the present invention includes a rotational speed detecting means for detecting a rotational speed N of the shaft supported by the bearing, wherein the current calculating means calculates a torque corresponding to the life component current component ILh, and calculates a life calculating means. Is characterized in that the life Lh of a bearing is calculated from a bearing load F corresponding to the torque, a rotation speed N detected by a rotation speed detecting means, and a predetermined rated load C of the bearing.

According to the present invention, the current calculation means calculates a torque corresponding to the life calculation current component ILh. For example, this torque is almost directly proportional to the life calculation current component ILh. Corresponding to the bearing load, for example, the bearing load is almost directly proportional to the torque, and the torque is a value corrected by the inertia torque corresponding to the rotation speed of the shaft, and the bearing load corresponding to the corrected torque is calculated. Thus, the life Lh of the bearing can be calculated.

According to the present invention, there is further provided a means for determining a plurality of types of operating states of an industrial robot, and an operating time measuring means for measuring an operating time ti of each operating state in response to an output of the operating state determining means. The life calculating means includes a means for calculating the average speed Nm of the shaft in response to the output of the operating time measuring means, and calculating an average value Fm of the varying bearing load using the calculated average speed Nm. , Calculating the life Lh of the bearing.

According to the present invention, a plurality of types of operating conditions are determined by the determining means, the operating time ti is measured by the operating time measuring means, the average speed Nm is obtained, and the average load Fm is calculated. The life Lh of the bearing can be calculated.

The present invention also includes means for detecting the angular acceleration ωa of the output shaft of the motor. The life component current component calculating means responds to the output of the angular acceleration detecting means and converts the detected angular acceleration ωa. A first current component I1 required to rotate a rotating part including an output shaft of the motor itself, and a second current component necessary to move a power transmission part from the output shaft of the motor to the component. Sum with I2 (= I1 +
I2) is obtained, and the current component ILh for life calculation is obtained by subtracting the sum of the first and second current components I1 and I2 obtained from the load current IM of the motor.

According to the present invention, in order to extract and calculate the life calculation current component ILh from the motor load current IM,
Since the angular acceleration ωa of the output shaft of the motor is detected and the sum of the first and second current components I1 and I2 is calculated based on the angular acceleration ωa, the accuracy of the momentary force calculation itself can be easily increased. Will be possible.

[0029]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention. Each axis of the industrial robot 1 having a plurality of (for example, six) axes is driven by a motor 2 such as a servomotor or a pulse motor. An operation such as spot welding is performed by the industrial robot 1. The motor 2 drives a base, an arm, a wrist, or the like. The rotation position of the output shaft of the motor 2 is detected by the encoder 3.

The control device 4 for controlling the industrial robot 1 includes a processing circuit 5 realized by a microcomputer or the like and driving means to which a position and speed command signal for each axis from the processing circuit 5 is given. It includes a certain servo amplifier 6 and a rotation speed detecting means 7 which receives an output from the encoder 3 and detects the rotation speed of the output shaft 15 of the motor 2. The angular acceleration calculation means 16 responds to the output from the rotation speed detection means 7 and calculates and detects the angular acceleration ωa, which is the rate of time change of the rotation speed of the output shaft 15. The outputs of the rotation speed detecting means 7 and the angular acceleration detecting means 16 are provided to the processing circuit 5, and the output of the load current detecting means 14 described later is also provided to the processing circuit 5. Processing circuit 5
Performs servo control of the motor 2. The processing circuit 5 further includes one processing circuit 8, an input / output interface 9, a man-machine interface 10, a read-only memory 11, and a random access memory 12.
Are connected. The man-machine interface 10 includes a display unit 13. This display means 13
Visual display means for realizing visual display realized by a cathode ray tube or a liquid crystal display panel, or acoustic display means including a voice synthesis circuit and a speaker may be used. Further, a combination of visual display means and sound means may be used. The servo amplifier 6 includes a load current detecting unit 14 for detecting a load current of the motor 2.

Teaching data including the position and speed of each axis of the industrial robot 1 is stored in the memories 11 and 12. In this way, a plurality of programs are sequentially selected and executed, whereby operations such as spot welding are sequentially performed.

FIG. 2 is a perspective view schematically showing a path for transmitting power from the motor 2 to a driven body 17 such as an arm or a wrist driven by a movement such as rotation by the motor 2. It is. The bearing 18 whose life is to be measured according to the invention supports a shaft 19. Bearing 18
In measuring the life of the motor 2, under the condition of the dynamic force, the dynamic force FD3 transmitted from the bearing 18 and thereafter (rightward in FIG. 2) is obtained separately from the dynamic torque of the motor 2. A dynamic torque component necessary to rotate the rotating part 21, which includes the output shaft 15 of the motor 2 itself, and a speed reducer 24 connected to the output shaft 15 of the motor 2
The dynamic torque component required to move the power transmission portion 22 to the bearing 18, including such as, must be subtracted. Under static force conditions, a static torque of the motor 2 is required for measuring the life of the bearing 18.

FIG. 3 is a flowchart for explaining the operation executed by the processing circuit 8 for measuring the life of the industrial robot of the present invention. A program that executes this flowchart is stored in the memories 11 and 12.
The process proceeds from step a1 to step a2, where the load current IM of the motor 2 is detected. The load current IM of the motor 2 is expressed by a current component I corresponding to a static force, as shown in the following equation 1.
It is the sum of S and the current component ID corresponding to the dynamic force.

IM = IS + ID (1) Here, the current component ID corresponding to the dynamic force is divided into the following three components I1, I2, and I3.

ID = I1 + I2 + I3 (2) In the above equation 2, the first current component I1 is a current component necessary for rotating the rotating part 21 including the output shaft 15 of the motor 2 itself. . The second current component I2 is a current component necessary for causing the power transmission portion 22 from the output shaft 15 of the motor 2 to the bearing 18 to make a motion such as rotation. The third current component I3 is a current component corresponding to the dynamic force FD3 transmitted from the bearing 18 thereafter. In measuring the life of the bearing 18, the motor current components related to the force acting on the bearing 18 are only the current component IS corresponding to the static force FS and the third current component I3. However, of the load current IM detected by the load current detection means 14, it is not possible to separate and measure only the life calculation current component ILh which is the sum of the current components IS and I3.

ILh = IS + I3 (3) Therefore, in the present embodiment, the first and second current components I
1, I2 is determined as follows, and the life component current component ILh is determined by subtracting it from the load current IM of the motor 2, thereby improving the accuracy of the load estimation of the bearing 18.

At step a3, the rotation speed detecting means 7 detects the rotation speed N0 of the output shaft of the motor 2. The angular acceleration calculating means 16 obtains the time change rate of the rotation speed N0, and obtains the angular acceleration ωa in step a31.
Further, in step a32, the first and second current components I1 and I2 are calculated and obtained based on Expressions 4 and 5.

I1 = K1 · J1 · ωa (4) I2 = K2 · J2 · ωa (5) ILh = IM− (I1 + I2) (6) where K1 and K2 are constants. J1 is the moment of inertia of the rotating part 21. J2 is the moment of inertia of the power transmission portion 22.

Therefore, in step a33, the life component current component ILh is calculated by subtracting the sum of the first and second current components I1 and I2 from the load current IM based on the equation (6). In step a4, a torque T _M corresponding to the life calculation current component ILh is calculated and obtained.

T _M = K _M · ILh (7) where K _M is a torque constant.

The bearing load P acting on the bearing 18 supporting the shaft 19 driven by the output shaft 15 of the motor 2 is determined by the input torque Ti of the shaft 19 supported by the bearing 18.
It is almost proportional to

P∝Ti (8) This input torque Ti is proportional to the torque T _M.

Ti∝T _M (9) In step a5, the rotational speed N0 (rpm) of the shaft 19 supported by the bearing 18 whose life is to be measured is calculated and obtained.

N = R · N0 (10) Here, R is a reduction ratio of a configuration including a drive system 22 such as a speed reducer driven by the output shaft 15 of the motor 2.

In step a8, a bearing load F is calculated and obtained. F∝T _M (11) In this way, the bearing load F corrected in consideration of the inertia torque of the motor 2 and the like can be obtained.

In step a9, the fatigue life L of the bearing
h is expressed by Expression 12, where C is the dynamic load rating of the bearing, F is the actual load acting on the bearing, and N is the rotation speed of the shaft 19 supported by the bearing 18.

[0047]

(Equation 1)

Here, q is q = 3 for a ball bearing, and q = 10/3 for a roller bearing. The unit of the life Lh is time, and the unit of the load is Newton or k.
gf.

In step a10, the ratio η of the actual operation time W1 to the life Lh of the bearing is calculated and obtained.

Η = W1 / Lh (13) The actual operation time W1 is obtained, for example, by measuring the drive time of the motor 2 by time measurement means in step a2 or the like.

In step a11, the remaining ratio (1-η) until the life of the bearing is determined, and the remaining time W2
Is calculated.

W2 = (1−η) Lh = Lh−W1 (14) In step a12, as shown in Table 1, for example, the life Lh,
Elapsed ratio η, remaining ratio (1−η) and remaining time W
2 is visually displayed, for example, in a table format. In another embodiment of the present invention, the contents of Table 1 may be displayed by the display means 13 in audio.

[0053]

[Table 1]

Although the embodiment described in connection with FIG. 2 describes the case where the load and speed of the shaft supported by the bearing whose life is to be measured are constant, another embodiment of the invention is described. Here, (a) when the load and speed fluctuate, and (b) when the operating conditions change in the middle, for example, when there is a change in teaching, and when a plurality of programs are selected in order or executed by an external command For example, the operation shown in FIG.
The processing is performed by the processing circuit 8. B1 to b13 in FIG.
b31, b32, and b33 correspond to step a1 in FIG.
To a13, a31, a32, and a33, respectively. Particularly in this embodiment, in step b21,
It is determined whether the operating state i has changed and the operating state i has started. The change of the operation state i is, for example, as described above, (a) when the load and speed fluctuate, and (b) when the operating conditions change and the teaching content changes during the course, or when a plurality of teaching conditions change. This is the case when the programs are executed sequentially, or when another program is executed by an external command. After the operation state i is changed and started, step b
Steps b8, b31 and b32 are executed. The rotational speed of the shaft supported by the bearing whose life is to be measured for each operating state i is denoted by the reference Ni, and the bearing load for each operating state i is denoted by the reference i.

In step b81, the aforementioned step b2
It is determined whether the operation state i started in step 1 has ended. That is, whether or not the load and the speed have changed, and if the operating condition has changed in the middle, it is determined, and the process proceeds from step b81 to the next step b82. In step b82, the operation time ti in the operation state i is measured from step b2 described above. Step b
At 83, the average speed Nm of the shaft is calculated.

[0056]

(Equation 2)

Thus, the load Fm is obtained by Expression 16.

[0058]

(Equation 3)

In step b9, the fatigue life Lh of the bearing can be calculated and obtained by substituting the above-mentioned average load Fm as the bearing load F in the above-mentioned equation (12). The ratio η is obtained, and in step b11, the remaining ratio (1−η) and the remaining time W2 can be calculated and obtained. The life Lh, η, (1−η) and W2 obtained in this manner are displayed on the display unit 1.
3 and the series of operations is terminated in step b13.

According to the present invention, the life is measured based on a value corresponding to the third or almost the third power of the load current of the motor, not only for bearings but also for other components constituting an industrial robot. can do.

[0061]

According to the first aspect of the present invention, it is possible to evaluate the load condition of the bearing, which is one of the main life factors of the mechanical part of the industrial robot. Preventive maintenance for occurrence of failures, such as determination of the timing of maintenance and replacement of parts such as bearings, can be reliably performed.

Since the use history of the industrial robot can be quantitatively determined in this manner, the safety rate of component replacement during maintenance of the industrial robot can be reduced, and the maintenance cost is reduced. In this way, effective preventive maintenance can be performed, and reliability can be improved and maintenance costs can be saved without excess or shortage.

Further, according to the present invention, it is easy to find out the cause of a failure at the time of a sudden failure of an industrial robot, and thereby it is easy to prevent the failure from reoccurring. This also improves the maintenance reliability. Quantitative maintenance becomes easy.

Further, according to the present invention, it is possible to implement the present invention simply by changing the computer program, using the configuration originally provided in the control device of the industrial robot as it is. The implementation of the present invention is easy.

According to the present invention, not only the bearing, which is a component of the industrial robot, but also the life of the other components is improved.
The calculation can be performed based on a calculation value related to the cube of the load current.

In particular, according to the present invention, only the life component ILh required for measuring the life of components such as bearings is extracted and obtained from the load current IM, and the life is calculated by this. , The life of the component can be accurately measured. This allows the user to know exactly what maintenance period is really needed.

According to the second aspect of the present invention, the life L of the bearing
h is the bearing load F, the rotational speed N, and the rated load C of the bearing.
Thus, the life of the bearing can be accurately calculated and obtained.

According to the third aspect of the present invention, when the operating state of the industrial robot changes, for example, when the load and speed of the industrial robot change, or when the industrial robot changes,
When the operating conditions change, for example, when the contents of teaching change, or when a plurality of programs are selected or executed in sequence or by an external command, the load current, rotation speed, and operating time in each operating state Thus, the average value Fm of the varying bearing load can be calculated, and the life Lh of the bearing can be calculated from the average value Fm thus obtained. Thus, even when the bearing load fluctuates, the present invention can calculate the life Lh of the bearing.

According to the fourth aspect of the present invention, the load necessary for measuring the life of the component is determined based on the angular acceleration ωa of the output shaft of the motor, based on the first and second current components I1, I2.
2, the life component current component ILh can be easily extracted and obtained from the load current IM. As a result, the accuracy of the load estimation can be easily improved.

According to the fifth aspect of the present invention, the load current of the motor is detected by the current detecting means, and the calculated value related to the cube of the load current is calculated by the current calculating means. The life of the element is calculated, and the calculated life is reported by visual or acoustic notification means.As described above, the load conditions of components such as bearings are evaluated, and the Preventive maintenance of the occurrence of failures such as inspection of components, maintenance, and determination of parts replacement time can be reliably performed.

According to the present invention, the current calculation means calculates the torque corresponding to the load current, thereby obtaining the bearing load F, and calculating the life Lh of the bearing from the rotation speed N and the rated load C. Thus, the calculation of the life of the bearing can be performed accurately.

According to the seventh aspect of the present invention, when the load acting on the bearing varies, the average load is determined so as to have a life equal to the fatigue life of the bearing under the varying load conditions. Calculate and know the bearing life accurately.

According to the present invention, the accuracy of estimating the load acting on the component whose life is to be measured is estimated based on the angular acceleration ωa of the output shaft of the motor. , I2, the accuracy of the load estimation can be easily improved.

In the present invention, not only the bearing but also other components may be used. In the components other than the bearing, only the calculation formula for calculating the life Lh is different. It can be obtained by an operation value related to the power.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of an embodiment of the present invention.

FIG. 2 is a simplified perspective view showing a path through which power is transmitted from a motor 2 to a driven body 17 such as an arm or a wrist driven by a movement such as rotation by the motor 2.

FIG. 3 is a flowchart for explaining an operation executed by a processing circuit 8 for measuring the life of the industrial robot of the present invention.

FIG. 4 is a flowchart for explaining the operation of another embodiment executed by the processing circuit 8 for measuring the life of the industrial robot of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Industrial robot 2 Motor 3 Encoder 4 Control device 5, 8 Processing circuit 6 Servo amplifier 7 Rotation speed detection means 10 Man-machine interface 11 Read-only memory 12 Random access memory 13 Display means 14 Load current detection means

 ──────────────────────────────────────────────────の Continuation of the front page (71) Applicant 000003470 Toyota Koki Co., Ltd. 1-1-1, Asahi-cho, Kariya-shi, Aichi (72) Inventor Kenkazu Sonoda 1-1-1, Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries, Ltd. Inside the Akashi Plant (72) Inventor Kazushige Suita 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Kiyoshi Kaniya 1-1-1 Fujikoshi Honcho, Toyama City, Toyama Prefecture Fujikoshi Inn ( 72) Inventor Kuniyuki Niwa 1-1-1, Asahi-cho, Kariya-shi, Aichi F-term (reference) 3F059 CA00 DA07 DC00 GA00 5H269 AB33 BB17 NN04 NN07 9A001 BZ03 HH19 HZ34 KK31 KK37

Claims (8)

[Claims] 1. A load current IM of a motor for driving an axis of an industrial robot having a plurality of axes is detected, and a static force FS of the load current IM acting on a component constituting the industrial robot is detected. Current component IS corresponding to
And a dynamic force FD3 subsequently transmitted from said component
Is calculated by calculating the sum of the current component I3 and the current component I3, and a calculated value related to the cube of the life calculation current component ILh is calculated based on the calculated value. A method for measuring the life of an industrial robot, comprising calculating the life of components constituting the robot. 2. A bearing load F corresponding to the calculated value is calculated, a rotation speed N of a shaft supported by the bearing is detected, and the calculated bearing load F, the rotation speed N, and a rated load of the bearing are calculated. 2. The method for measuring the life of an industrial robot according to claim 1, wherein the life Lh of the bearing is calculated based on C. 3. An operating time ti of each of a plurality of types of operating states of the industrial robot is measured, an average speed Nm is calculated for each operating state, and the average speed Nm obtained by the calculation is used. 3. The method for measuring the life of an industrial robot according to claim 2, wherein the life of the bearing is calculated by calculating an average value Fm of the varying bearing load. 4. Detecting an angular acceleration ωa of an output shaft of the motor, and using the angular acceleration ωa, a first current component I1 necessary for rotating a rotating portion including an output shaft of the motor itself, The sum (= I1) of the second current component I2 necessary to move the power transmission portion from the output shaft to the component.
+ I2), and a current component for life calculation ILh is obtained by subtracting the sum of the first and second current components I1 and I2 obtained from the load current IM of the motor. 4. The method for measuring the life of an industrial robot according to one of the three aspects. 5. A current detecting means for detecting a load current of a motor driving an axis of an industrial robot having a plurality of axes, and a current component calculating means for calculating a life, wherein the load current I
Of M, a current component IS corresponding to a static force FS acting on a component constituting the industrial robot and a current component I3 corresponding to a dynamic force FD3 transmitted from the component thereafter. Calculate the sum to calculate the life component current component ILh
A current component calculating means for calculating the life component of the current component ILh in response to the output of the life component calculating current component calculating means, An industrial robot comprising: a life calculating means for calculating a life of a constituent element of an industrial robot in response to an output; and a notifying means for displaying or acoustically outputting the life calculated by the life calculating means. Life measuring device. 6. The rotation speed N of a shaft supported by a bearing.
The current calculation means calculates a torque corresponding to the life calculation current component ILh, and the life calculation means includes a bearing load F corresponding to the torque,
6. The device for measuring the life of an industrial robot according to claim 5, wherein the life Lh of the bearing is calculated from the rotation speed N detected by the rotation speed detecting means and a predetermined rated load C of the bearing. 7. An operating robot comprising: means for determining each of a plurality of operating states of an industrial robot; and operating time measuring means for measuring an operating time ti of each operating state in response to an output of the operating state determining means. The calculating means responds to the output of the operating time measuring means, calculates an average speed Nm of the shaft, and calculates an average value Fm of the fluctuating bearing load using the calculated average speed Nm. 7. The device for measuring the life of an industrial robot according to claim 6, wherein the life Lh is calculated. 8. A motor further comprising means for detecting an angular acceleration ωa of an output shaft of the motor, wherein the life component calculating current component calculating means responds to an output of the angular acceleration detecting means and uses the detected angular acceleration ωa to A first current component I1 required to rotate a rotating portion including an output shaft of the motor itself, and a second current component I2 necessary to move a power transmission portion from the output shaft of the motor to the component. Sum (= I1
+ I2), and calculating the life component ILh by subtracting the sum of the first and second current components I1 and I2 obtained from the load current IM of the motor. 8. The device for measuring the life of an industrial robot according to claim 7.