JP2000148224A - Controller for machining robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the controller for the machining robot which makes the best use of the capability of a tool and which makes specific operation proceed efficiently in a system which carries out deburring and machining by using various tools and cutting tools. SOLUTION: When the state wherein a measured value of a load reacting to a tool, etc., is between a specific set value based upon a target load and a unloading value through the process in a step S12 is detected, the 'upper-limit' level as the level of the load which autonomously and temporarily stops before the machining robot enters a complete stop position is reduced through the process in a step S14 corresponding to the feed speed, and then the speed command is set above 100% through the process in a step S15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a machining robot, and more particularly, to a control device for an industrial robot which is useful when applied to a machining robot for performing deburring and cutting using various tools and blades. .

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing a machining robot according to the prior art for performing deburring, cutting, and the like using various tools and blades. In the figure, 1 is a robot body, 2
Is a robot controller of a teaching playback system, 3 is a continuous feed speed control unit, 4 is a high-frequency electric tool attached to the arm of the robot main body 1, and 5 is an inverter device used as a power supply of the high-speed electric power tool 4. A drive motor of the high-frequency electric tool 4, for example, an induction motor 4M is connected to an output terminal of the inverter device 5, and a load current and a voltage thereof are detected and used as an input of a load transducer (power converter) 6.

The robot controller 2 has a management CP
U2-1, data memory 2-2, control CPU 2-3, position detection interface 2-4, servo interface 2-5, servo driver 2-6, and I / O interface unit 2-7. The I / O interface unit 2-7 includes a D / I interface 2-7A, a D / O interface 2-7B, and an A / D
It has a converter 2-7C.

[0004] The CPU 2-1 has a function of performing an inching operation for moving the robot to an arbitrary position, a teaching operation (man-machine interface), and storing and reproducing teaching data. Also, depending on the condition of each input / output signal,
Perform adaptive control to change the operation speed. Data memory 2
-2 stores teaching data and control parameters. The control CPU 2-3 controls each axis of the arm based on the teaching position data provided from the management CPU 2-1. The position detection interface 2-4 gives a pulse from an absolute (ABS) encoder attached to the servomotor of each axis to the control CPU 2-3. The servo interface 2-5 converts each axis operation angle command from the control CPU 2-3 into pulse data 5 to be given to the servo driver 2-6. The servo driver 2-6 drives the motor of each axis. The D / I interface 2-7A inputs a digital signal. The D / O interface 2-7B outputs a digital signal. A / D converter 2-7C converts an analog signal into a digital signal.

[0005] The robot controller 2 in this embodiment is provided with an A / D converter 2-7C as an I / O interface of a general teaching playback system controller.
And the voltage signal is set to 0 V to 0 to full scale.
It can be handled by converting it to 100% internal data.

[0006] The continuous feed speed control unit 3 is provided with a fuzzy (FUZZY) calculation CPU 3-2, an A / D converter 3-3, and a D / A converter. A device 3-4, a D / O (digital output device) 3-5, and a D / I (digital input device) 3-6 are connected by a data path.

The load transducer 6 measures the input power of the tool 4 and outputs a voltage proportional thereto. This output voltage is input to the A / D converter 3-3 of the continuous feed speed control unit 3.

In the above configuration, it is possible to set a load which exerts the maximum performance on the tool 4 irrespective of rotation and vibration. In this example, in order to always follow the load, the load deviation and the rate of change of the deviation are constantly monitored.
It is characterized in that the acceleration is calculated by FUZZY inference according to the change, integrated, fed to the robot controller 2 as a speed command, and the load of the tool 4 is adjusted by changing the feed speed. As a result, the prior art is
It has a high ability to cope with burrs and is useful as a technology for improving the processing efficiency of industrial robots and automatic machines.

FIG. 3 is a flowchart showing the flow of basic signal processing of the machining robot. The operation of the processing robot will be described with reference to FIG. The continuous feed speed control unit 3 stores in advance an initial set value and knowledge required for FUZZY control. When the power is turned on, first, the target load value A _s and other parameters are set (step S1). Subsequently, the output voltage signal of the load transducer 6 is converted into internal data by the A / D converter 3-3 of the continuous feed rate control unit 3 (S2). The converted data is pre-processed by the CPU 3-1. In other words, it calculates a load deviation .DELTA.A _i from the load measured values A _i by subtracting the target load value A _s (S3). To match the input range of the membership function, ΔA _i is multiplied by the gain G ₁ to calculate ΔA _{IN P} (S4). The change rate Δa _{i of the} deviation is calculated by subtracting ΔA _i−1 calculated in the previous processing from ΔA _i (S5). To match the input range of the membership function, calculating a .DELTA.a _INP is multiplied by the gain G ₂ in Δa _i (S6). After that, the FUZZY calculation CPU 3-2
Performs FUZZY inference (S7). Where FU
In order to obtain an inference result using knowledge of ZZY control (rules and membership functions), a centroid method which is a general method of FUZZY inference may be used.

The calculation result in step S7 is output as the acceleration ΔV _OUT of the speed command. Then, the gain G _{3 is} added to the acceleration ΔV _OUT so that the amount of increase and decrease becomes optimum.
The multiplied calculates the [Delta] V _i (S8), which adds to the speed integrated value V _i-1 output in the previous process (integration) and a velocity command value V _i to (S9). Velocity command value V _i is output to the robot controller 2 through the D / A converter 3-4 (S10). In the robot controller 2, the analog input voltage is converted to 0 to 100% by the A / D converter 2-7C (S11). By multiplying this output value by the designated speed at the time of teaching, the feed speed at the time of machining is changed.

The continuous feed speed control unit 3 monitors the operation state of the tool 4 with the load transducer 6, and outputs a "grinder abnormal" signal to the robot controller 2 when it is determined that the tool 4 has failed. Further, when the load increases so rapidly that even the above control cannot complete the processing, a signal for stopping the robot 1 is output to protect the tools / cutting tools and the robot.

[0012]

The prior art as described above is useful as a technique for improving the processing efficiency of industrial robots and automatic machines, but the following problems remain in the prior art. .

After detecting an overload, a stop signal or a deceleration command voltage is applied to the scale unit CPU of the robot controller.
And there is always an increase in overload due to a delay caused by signal processing until the robot actually stops or decelerates.

The same applies to the case where continuous feed control is performed.
Due to the delay with respect to the deceleration command voltage and the stop signal, there is a limit to the feed speed specified by the robot controller (when the deceleration command voltage is 100%), and the set value is set to the maximum value that can be controlled without locking the tool. (When using 5kw electric angle grinder, 50mm / sec
c).

Since the size of the burrs of the casting is generally unstable, even if the burrs may be generally large, the burrs may fall off during the sand removal process and may not be attached. In this case, the speed designation is set low in order to assume that a large burr will occur. Even if the load is small, the speed command voltage has an upper limit of 100%, so that the speed cannot be further increased and the efficiency is reduced.

The present invention has been made in view of the above-mentioned conventional technology, and in a system for performing deburring and machining using various tools and cutting tools, a predetermined work can be efficiently performed by maximizing the capability of the tool. It is an object to provide a control device for a processing robot.

The structure of the present invention that achieves the above object detects the load on the tool and changes the feed rate so that the load becomes the target load. The change in the feed rate is based on the deviation of the tool load from the target load. In the control device of the machining robot, which performs the fuzzy inference based on the change rate and controls the tool to move at the feed speed determined by the fuzzy inference, the measured value of the load is a predetermined set value based on the target load. When the speed command is between 100% and no load, the speed command is set to 100% or more, and at the same time, the speed command is set to 100%
In the case specified above, control is performed so that the highest level, which is the level of the load that temporarily suspends before the machining robot completely stops, is reduced in accordance with the feed rate. Features.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a flowchart showing a processing procedure in the control device of the processing robot according to the embodiment of the present invention. The processing shown in the figure is realized by the processing robot shown in FIG. 2, and many processings are the same as those in the flowchart of FIG. Therefore, the same processes as those in FIG. 3 are denoted by the same reference numerals, and redundant description will be omitted.

As shown in FIG. 1, the present embodiment is obtained by adding steps S12 to S15 after the step S9. Specifically, (target load A _s + α) ≧
It is determined whether or not (measured load value A _i )> (no load) (step S12). As a result, when the load measurement value A _i is the target load A _s + α (α offset values for expected variations that can follow the target load by the action of the control.) Greater than, since already in the region of the overload, step Proceeding to the processing of No. 13, the same processing as the conventional one shown in FIG.
The speed command value _{V i MAX (= 100%)} . Similarly,
If the measured load value _Ai is zero (= no load), the workpiece is not being machined by the tool in this case, but is moving to the next machining position.
Is performed. This is because the operation speed in this case is too fast unless it is as specified by the program.

On the other hand, if (target load A _s + α)> (measured load value A _i )> (no load), the process proceeds to step S14 and then to step S15. Specifically, first, at step 14, reduce the level of "an uppermost" load according to the magnitude of the velocity command value V _i. This is because, due to a delay in signal processing due to a sudden increase in load, the amount of load increase from the detection of overload to the actual stop increases according to the magnitude of the feed speed, and the upper limit set value remains the same. This is because there is a risk that the tool will stop, and if the level of the "maximum limit" is lowered, it is possible to increase the margin before the tool exceeds the capability and locks.
Here, the “maximum limit” level refers to a load level at which the processing robot temporarily suspends spontaneously before completely falling into a stopped state. The maximum value of the velocity command value V _i in this embodiment is set to 200%, and can specify up to twice the speed of the feed rate specified by the program. Maximum value of the velocity command value V _i in this case the robot controller 2 (FIG. 2
reference. ) Can be easily changed by the parameter of (2), and is not limited to 200% as in the present embodiment.

The signal after the processing in step S13 or S15 is completed is processed in the same manner as in the prior art (steps S10 and S11).

The robot controller 2 (see FIG. 2) used in this embodiment is a general teaching playback type, and its I / O interface 2-7.
(See FIG. 2), an A / D converter can be added, and the voltage signal is 0 V to 0 to 10 with respect to full scale.
Although it could be handled by converting it to 0% internal data, it was improved so that the conversion rate could be changed. As a result, the feed speed at the time of machining is changed by applying the designated speed at the time of teaching. In an actual operation, since the operation is performed at a speed obtained by multiplying the speed set by the program of the robot controller 2 by the internal data, the speed is reduced in the case of 0 to 100%,
In the case of 00 to 200%, an operation of increasing the speed can be realized. Note that after reset the maximum value of the load in correspondence to the speed command value V _i, again (target load A _s + alpha)> (load measurements A _i)> If the condition of (no load) is satisfied In
Reset it. This is to prevent the state where the “maximum upper limit” level remains lowered.

[0024]

As described above in detail with the embodiments, the present invention has the following effects. If the load during processing satisfies a certain condition, the feed rate can be increased to a value higher than the value specified by the program by setting the speed command ratio to 100% or more, so that predetermined processing can be performed efficiently. When the control is performed, the level of the "upper limit" is lowered in accordance with the speed, so that even if the feed speed increases, a margin can be provided even for a sudden increase in load. As a result, it is possible to improve the processing efficiency without stopping the apparatus.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a processing procedure according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a processing robot to which the control device of the present invention is applied.

FIG. 3 is a flowchart showing a processing procedure according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Robot main body 2 Robot controller 3 Continuous feed speed control unit 4 High frequency electric tool

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 3F059 AA06 BA10 CA01 FA01 FC02 5H004 GA16 GB15 HA08 HA16 HA20 HB07 HB08 HB14 JA13 JA23 JB09 JB18 KD02 KD24 5H269 AB07 AB33 BB05 EE01 NN07 NN17 PP15 QC10 9A001 FF07 KK07

Claims (1)

[Claims] A feed rate of a tool is detected and a feed rate is changed so that the load becomes a target load. The feed rate is changed using fuzzy inference based on a change rate of a deviation between a tool load and a target load. In the control device of the processing robot, which controls the tool to move at the feed speed obtained by the fuzzy inference, when the measured value of the load is between a predetermined set value based on the target load and no load Is the load level at which the speed command is set to 100% or more, and at the same time, when the speed command is set to 100% or more in this way, the machining robot temporarily stops temporarily before completely falling into a stopped state. A control device for controlling the processing robot so as to reduce the uppermost level corresponding to the feed speed.