JPH0981215A - Robot control device and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device capable of monitoring the arrival of a real replacing period of parts, calculating remaining durable time and detecting various maintenance and inspection periods by providing the device with an operation means for inputting a 1st signal outputted from a monitoring means and outputting a 2nd signal for computing the accumulated damage degree of each power transmission means. SOLUTION: Respective joints J1 to J3 (power transmission means) of a manipulator 10 are driven by respective motors M1 to M3 controlled by a control device 20. Namely the outputs of respective motors M1 to M3 are decelerated by a speed reducer and then applied to respective joints J1 to J3 through the transmission mechanisms to drive them. An operation part 23 provided in the device 20 finds out the accumulated damage degree of respective joints J1 to J3 based upon the monitored result of a monitor part (monitoring means) 25 and operation signals applied from an encoder to respective joints J1 to J3. The maintenance periods, remaining durable time or replacing time of respective joints J1 to J3 are detected based upon the accumulated damage degree and informed through a display part 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot control apparatus and control method for informing maintenance time of rotating parts and the like.

[0002]

2. Description of the Related Art Reduction gears used for manipulators,
The load capacity of a power transmission component such as a bearing or a gear has been determined so as not to be damaged for a predetermined period, assuming that the component continuously operates in an operation pattern determined at the time of design. At the same time, the maintenance and the timing of the maintenance were decided uniformly regardless of the actual operating conditions.

[0003]

Needless to say, in the above-mentioned prior art, since the actual usage condition and usage frequency of each component are not taken into consideration, it is necessary to know the true replacement time (this is called the life). I can't. Therefore, even for parts that are infrequently used and have a long service life, maintenance or replacement is unavoidable at regular intervals less than the true life.
There is a problem that maintenance man-hours and parts are wasted.

The present invention has been made under such a background, and it is possible to monitor the arrival of the true replacement time of parts, calculate the remaining durable time, and detect and notify various maintenance inspection times. An object of the present invention is to provide a control device and a control method of a robot that are possible.

[0005]

In order to solve the above-mentioned problems, in the invention described in claim 1, a motor for driving each part of the robot through a power transmission means, and a drive power to the motor. Monitoring means for monitoring the operating state of the motor based on the above, and a calculation for inputting a first signal output by the monitoring means and calculating a cumulative damage degree of the power transmission means to output a second signal. And means.

According to a second aspect of the present invention, in the robot controller according to the first aspect, the monitoring means is configured to detect the torque generated by the shaft of the motor based on the drive power. The rotation speed of the shaft of the motor is detected and output.

According to the third aspect of the invention, there is provided a first stroke for inputting a first signal indicating a driving state of a motor for driving each part of the robot via the power transmission means, and the first stroke. The second step of obtaining the limit repetitive rotation speed of the power transmission means based on the above signal, and the degree of damage per unit time of the power transmission means based on the first signal and the above-mentioned limit repetitive rotation speed. Comparing the cumulative damage degree with a predetermined reference value; and the fourth step for obtaining the cumulative damage degree of the power transmission means by integrating the damage degree calculated every predetermined time. And a fifth step, wherein the first step to the fifth step are sequentially repeated.

[0008]

According to the present invention, the calculating means calculates the degree of damage per unit time of the power transmitting means from the torque of the motor shaft and the rotation speed of the motor shaft which are detected and output by the monitoring means for monitoring the operating state of the motor. In addition, the maintenance time, the remaining life time, or the replacement time of the power transmission means is detected based on the accumulated damage degree, and the display means gives a notification.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

A. Configuration An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an overview of a robot (a generic term for manipulators and control devices) to which an embodiment of the present invention is applied. The robot described in this embodiment is, for example, a robot used in a coating process of an automatic manufacturing line.

In FIG. 1, each joint J1, J2 and J3 (power transmission means) of the manipulator 10 is a motor M1, M2 or M3 controlled by a controller 20.
(Not shown). That is, each motor M1
The outputs of M3 to M3 are decelerated by the speed reducer, and then drive the joints M1 to M3 via a transmission mechanism (all not shown).

FIG. 2 is a block diagram showing an outline of the connection of the control system of the robot shown in FIG. In FIG. 2, 23 provided in the control device 20 is a CPU (Central Pr).
ocessing unit: a computing unit (computing means) including a central processing unit). This calculation diagram 23 shows the cumulative damage degree of each of the joints J1 to J3 based on the monitoring result by the monitor unit (monitoring means) 25 described later and the operation signal from the encoder of each joint J1 to J3 (not shown). Ask. The information on the cumulative degree of damage is, for example, CRT (Cathode Ray Tub).
e: Display unit (display means) 2 including a cathode ray tube
Displayed by 6.

The arithmetic unit 23 also calculates a control amount required for each of the motors M1 to M3 based on the feedback value from the encoder, and outputs a control signal to the driving unit (driving means) 2
4 The drive unit 24 is composed of a power amplifier or the like for driving the motors M1 to M3, and drive power is supplied to the motors M1 to M3 and the monitor unit 25.
The monitor unit 25 is composed of a current sensor, a voltage sensor and the like, and monitors the operating state (torque, speed, etc.) of each of the motors M1 to M3 from this information.

B. Control Method Next, from the operating state of each motor M1 to M3 (hereinafter, referred to as a motor Mn), each joint J1 to J3 corresponding thereto
A method for obtaining a cumulative damage degree (hereinafter, referred to as the joint Jn) will be described. It should be noted that, unless otherwise specified, the following description will refer to any one joint. The description of the other joints is omitted, but the same as the following description.

FIG. 5 is a flowchart showing an algorithm of a robot control method according to the first embodiment of the present invention. The calculation unit 23 has a counter function (not shown) for counting the count value i at each sampling time Δt therein.
The following processing is performed for each t. In addition, the calculation unit 23
Resets the count value i of the counter to 0 when the robot starts.
(Step Sa1).

In the present embodiment, the limit number of revolutions R with respect to the torque T for any one motor Mn is
The relationship is as shown in FIG. 3 as an example. The limit in this case is defined arbitrarily,
For example, the standard is a load that causes damage to the parts used for the joint Jn, or a state in which the performance deteriorates above a certain level.

According to the present invention, the limit number of revolutions is calculated according to the linear damage law, which is generally used as a guideline for cumulative fatigue damage, and the fatigue state of parts is judged based on whether or not this cumulative value reaches a predetermined value. To do.

Assuming that the fatigue damage progresses linearly with the revolving speed regardless of the magnitude of the torque T, the value of the limit revolving speed R with respect to the torque T can be obtained by the following equation.

[Equation 1] However, in the above equation, C1 and C2 are arbitrary positive real numbers.

Next, the calculation section 23 reads the torque Ti and the rotation speed ωi of the motor Mn from the monitor section 25 (step Sa2), and obtains the limit repetitive rotation number Ri for Ti based on the above equation (1) (step Sa2). Sa3).

In step Sa3, when the rotational speed ωi of the joint Jn and the limit rotational speed Ri are known, the damage degree di per predetermined time (sampling time Δt) is obtained. This damage degree di is calculated by the following equation.

[Equation 2]

That is, the calculation unit 23 obtains the damage degree di of the joint Jn per predetermined time based on the equation (2) (step Sa4). If i is 0 in the next step Sa5, the process proceeds to step Sa11 described later.

Now, at a certain time i when the robot is in operation, the torque Ti and the rotation speed ωi of the motor Mn are shown in FIG.
If the change occurs as shown in (a) or FIG. 4 (b),
The cumulative damage level dp is as shown in FIG. That is, the cumulative damage level dp can be expressed by the following equation.

(Equation 3) The calculation unit 23 calculates the cumulative damage level d based on the equation (3).
p is calculated (step Sa6).

According to the linear damage law of the present invention, when the dp becomes 1, the cumulative rotation speed up to that point and the critical repetition rotation speed match, that is, the life is reached. Therefore, the control device 20 is configured to monitor whether or not the cumulative damage level dp is 1 or less and display a message such as maintenance or replacement time according to the value.

For example, in the case of the speed reducer of the second shaft driven by the motor M2, when dp reaches 0.5, it can be determined that the period corresponds to half the life. That is, the calculation unit 23
Is determined to be 0.5 (step Sa
7). If dp reaches 0.5 here, the computing unit 23 prompts the robot administrator to inspect the display unit 2.
Display "Please replace the grease of the 2nd axis reducer" by step 6 (step Sa8), and then step Sa
Go to 11.

When the standard life time is 10 years, when dp is 0.9, the total operating time has passed 9 years. That is, the calculation unit 23 determines whether dp has reached 0.9 (step Sa9). If dp reaches 0.9, the computing unit 23 informs the user that the parts are about to be replaced, and the display unit 26 displays "This robot can be operated for one year in the existing usage condition. Will be displayed (step Sa10), and the next step S
Proceed to a11.

In the next step Sa11, after waiting for a predetermined time (sampling time Δt), 1 is added to the count value i of the counter included in the arithmetic unit 23. In step Sa12, it is determined whether the cumulative damage level dp has reached 1. If dp is less than 1, the process returns to step Sa2.

In step Sa12, the arithmetic unit 23
When it is determined that the cumulative damage level dp has reached 1, it is determined that the life of the component forming the joint Jn is reached as described above, the manipulator 10 is stopped, and the control process ends.

As described above, in the present embodiment, since the cumulative damage level dp is obtained according to the usage status and usage frequency of each joint Jn, the maintenance inspection time can be reasonably determined.

FIG. 6 is a flow chart showing an algorithm of a robot control method according to the second embodiment of the present invention. In the present invention, when the robot is configured to reproduce the taught data based on the taught data in advance, a value obtained by multiplying the cumulative damage degree dt for each teach data by the number of times N of reproduction of the teach data is repeated. , Can be regarded as the total cumulative damage level dp. That is, it is not necessary to monitor only the number of reproduction repetitions N and newly calculate the cumulative damage level when reproducing the teaching data.

That is, in this case, the counter included in the arithmetic unit 23 counts the number N of repeated reproductions of the teaching data.
First, the arithmetic unit 23 sets the count value N to 0 at the time of teaching, finds and stores dt corresponding to the cumulative damage level dp as in the first embodiment described above (step Sb).
1). On the other hand, since the life is reached when the cumulative damage level dt is 1, the number of reproduction cycles Ne with respect to the life is obtained as the reciprocal of the cumulative damage level dt (step Sb2).

After that, the calculation section 23 first confirms whether or not the number of reproduction repetitions N has reached 0.5 · Ne (step Sb).
3) If it has reached, the display 26 will display "Please replace the grease of the second axis reducer" (step S
b4) and then proceeds to the process of step Sb7 described later.

Further, the arithmetic unit 23 confirms whether or not the number of reproduction repetitions N has reached 0.9 · Ne (step Sb).
5) If it has reached, the display unit 26 displays "This robot has been used up to now and can operate for another year" (step Sb6), and proceeds to the next step Sb7.

In step Sb7, the arithmetic unit 23 adds 1 to the count value of the counter, and then in step Sb8, it is determined whether N has reached Ne. If N is less than Ne in step Sb8, the calculation unit 23 returns to step Sb3. On the other hand, in step Sb8, when N has reached Ne, it is determined that the life of the component forming the joint Jn is reached, and the manipulator 10
To stop the control processing.

As described above, in this embodiment, Ne
Is used as a reference value, and the maintenance and inspection time is examined based on the number of regeneration cycles N up to that point.

In the above embodiment, the manipulator 10 having a structure having three motors and three joints.
However, the number of motors and joints of the present invention is not limited to the number shown in this embodiment.

Further, the numerical values (0.5 and 0.9) which are the criteria for judging maintenance and replacement of parts are merely examples, and these values are determined by the use and material of the parts and maintenance items. Therefore, the values are not limited to the values shown in this embodiment. Needless to say, the text displayed on the display unit 26 is also an example for explaining the present invention.

[0036]

As described above, according to the present invention, the calculating means detects the power of the power transmission means from the torque of the motor shaft and the rotation speed of the motor shaft which are detected and output by the monitoring means for monitoring the operating state of the motor. The damage level per unit time is calculated, and the maintenance time, the remaining life time, or the replacement time of the power transmission means is detected based on the cumulative damage level and is notified by the display means. It is possible to realize a robot control device and control method capable of monitoring the arrival of the replacement time, calculating the remaining durable time, and detecting and notifying various maintenance inspection times.

That is, according to the present invention, firstly, the cumulative damage degree of the power transmission component of the robot can be determined without using a special measuring instrument (eg, ultrasonic flaw detector, AE measuring instrument, etc.).
Inspection costs can be reduced. Secondly, since the cumulative damage level is required with high precision, maintenance and inspection costs can be reduced by rationally determining maintenance and inspection times, and accidents when used under severe conditions can be prevented. . Thirdly, since the remaining life time is accurately required, it is possible to accurately predict the parts replacement time and reduce the waste of capital investment costs.
Fourthly, in the teaching reproduction type robot, since the lifespan of the parts can be examined only by obtaining the cumulative damage degree for each teaching data, the computing time can be shortened, and accordingly, the computing means can be simplified and the cost can be reduced. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a perspective view showing an overview of a robot to which an embodiment of the present invention is applied.

FIG. 2 is a block diagram showing an outline of connection of a control system of the robot shown in FIG.

FIG. 3 is a diagram showing an example of a relationship between a torque T and a limit repetitive rotation speed R with respect to the motor Mn in the embodiment.

FIG. 4 is a diagram showing a torque Ti of a motor Mn in the embodiment.
FIG. 6 is a diagram showing how the rotation speed ωi changes and the cumulative damage level dp for the change.

FIG. 5 is a flowchart showing an algorithm of a robot control method according to the first embodiment of the present invention.

FIG. 6 is a flowchart showing an algorithm of a robot control method according to the second embodiment of the present invention.

[Explanation of symbols]

 10 Manipulator 23 Calculation part 24 Drive part 25 Monitor part M1 to M3 motor J1 to J3 joint

Claims (3)

[Claims] 1. A motor for driving each part of a robot via a power transmission means, a monitoring means for monitoring an operating state of the motor based on driving power to the motor, and a first output by the monitoring means. A control device for a robot, comprising: a signal input and a calculation unit that calculates a cumulative damage degree of the power transmission unit and outputs a second signal. 2. The monitoring means detects and outputs the torque generated by the shaft of the motor and the rotation speed of the shaft of the motor based on the drive power. A control device for the described robot. 3. A first step of inputting a first signal indicating an operating state of a motor for driving each part of the robot via the power transmission means, and a limit of the power transmission means based on the first signal. A second step of obtaining a repetitive rotation speed, a third step of calculating the degree of damage per unit time of the power transmission means based on the first signal and the limit repetitive rotation speed, and at a predetermined time interval The fourth step includes a fourth step of accumulating the calculated damage degrees to obtain a cumulative damage degree of the power transmission means, and a fifth step of comparing the cumulative damage degree with a predetermined reference value. The method of controlling a robot, characterized in that the steps from the above to the fifth step are sequentially repeated.