JPH03170283A - Apparatus for controlling robot - Google Patents

Abstract

PURPOSE:To automatically teach with a small number of teaching points at high accuracy a working orbit of a robot for optimizing a working state of a tool against a workpiece consisting of curves by providing a means for correcting the teaching points while a robot is actually run. CONSTITUTION:When there is a portion which is not suitable with respect to a matrix 50 shape on a working orbit interpolated from a teaching point, a stroke amount of a floating cylinder device 20 fluctuates at the portion to be out of a specific threshold value. The unsuitable portion out of the specific threshold value is stored in an NG section storing means 4 as NG sections per section corresponding to an interpolating point, and the interpolating point of the section is compensated by a correcting means 5 after completion of running of the working orbit. A second running is done by a new working orbit based on the compensated interpolating point, and thereafter running of a robot 10 and compensation of each teaching point are repeated until the stroke amounts in all sections are within the specific threshold value.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industry-12 Application Fields" The present invention relates to industrial robots, and more particularly to a robot control device that can automatically teach motion trajectories. The device of the present invention is suitable for application to a cobot that performs polishing work.

``Prior art'' Generally, when a robot is moved along a predetermined trajectory to perform polishing work, a sensor is installed at the tip of the robot to detect the pressing force of the grindstone, as shown in Japanese Patent Application Laid-open No. 60-20858, for example. , apply a certain pressing force to the work start point and end point of the workpiece to be polished, and a predetermined position on the line connecting these two points, input the coordinate data, and check the coordinates. Based on the data, select linear interpolation or circular interpolation according to the shape of the workpiece, create interpolation data, and complete teaching. After this, the grindstone was moved from the created teaching date and the polishing work was performed while correcting the trajectory so that a constant pressing force was applied to the grindstone.

``Problem to be solved by the invention'' By the way, in the teaching described in 4: If the workpiece is a ▼ surface, the line between the work start point and the work end point can be drawn by linear interpolation. There is no need to input coordinate data of points for interpolation into the line -12 connecting the points. However, in the case of a curved surface, even if simple circular interpolation is used, the coordinates of multiple interpolation points must be memorized in order to accurately determine the curvature, making it difficult to perform teaching work. There was a problem in that the workload on the workers increased.

3. The present invention has been made to solve the problems mentioned in 2. The purpose of the present invention is to create a motion trajectory that conforms to actual machining with a small number of points, regardless of whether the workpiece is a curved or flat surface. An object of the present invention is to provide a robot 1 to a control device that can be automatically taught.

"Means for Solving the Problem" In order to achieve the above object, in the present invention, as shown in FIG. a floating cylinder mount W 20 that is held at one time; a distance sensor 28 that detects the stroke amount of the floating cylinder mount 20;
From the output of the distance sensor 28, the stroke amount is determined to be 1.
NG determination means 1 that determines that the deviation from the target value exceeds a predetermined threshold value and outputs an NG signal; teaching point storage means 2 that stores the target motion locus of the robot 10 as a teaching point; and interpolation between the teaching points. a traveling means 3 for causing the robot 10 to travel along a target motion trajectory; NG section memory 4 for remembering every section 4, correction step 5 for correcting the teaching point in order to move the interpolation point of the section where the NG signal occurs in the direction to make the stroke amount appropriate, and all of the above. There is provided a robot control device characterized in that it comprises a repetition means 6 for repeatedly executing the 1,000-stage traveling step 3, the NG section storage means 4, and the correction means 5 until no NG signal is generated in the section. .

In the robot control device configured as described in Section 2, each teaching point is first stored in the teaching point memory 2 by rough teaching. Next, the tool 27 is actually used as a model base material 5.
The robot l.10 is moved in a state in which it is in contact with the point 0, and the two teaching points are interpolated to correct the complementary and equal points.

In other words, if there is a location in the motion locus interpolated from the teaching point that is not appropriate for the shape of the base material 50, the fu n-
The stroke amount of the bearing cylinder device 20 fluctuates and deviates from the predetermined threshold value. Inappropriate points that are outside the predetermined threshold are stored as NG sections in the NG section memory 1,000 stages 4 for each section corresponding to the complementary equalization point, and after the movement trajectory has finished traveling, the interpolation point of the section is changed to the axis by the correction 1,000 steps 5. tE is done. Then, a second run is performed using a new motion trajectory based on the compensated +E interpolation points, and the robot continues to move until the stroke amount falls within a predetermined threshold in the entire area.
- 10 runs and correction of each teaching point are repeated.

Therefore, the initially roughly taught teaching point is such that the tool 27 contacts the base material 50 with a predetermined pressing force and the stroke amount of the floating cylinder assembly W 20 becomes a constant value within a predetermined threshold value over the entire operation trajectory. This is corrected by automatic operation.

“Embodiment 1 An embodiment of the present invention will be explained with reference to the drawings.
The figure is a perspective view without showing the robot 10.

This robot is a multi-jointed robot with 6 self-height degrees, and performs polishing work using a rotating grindstone 27 attached to the tip of the arm. The workpiece is an automobile frame, and the bead where the biller and roof are joined by arc welding is polished to ensure a smooth finish.

The structure of the IV pot will be explained. Fixed base].
]-1 A trapezoidal swing head 12 is rotatably supported in a horizontal plane about a vertical first axis A1, and is driven to swing by a first shaft drive motor M1. A first arm 13 is supported on the swing base 2 so as to be swingable about a horizontal second axis A2, and is swingably driven by a second axis drive motor M2. A cylindrical second arm 14 is supported by the first arm 1342 so as to be swingable about a horizontal third axis A3, and is swingably driven by a third axis drive motor M3 (not shown). At the tip of the second arm 14, twist squirrels 1 to 15 are rotatably supported around a fourth axis A4 at the center of the second arm 14, and are rotationally driven by a fourth axis drive motor M4. A pend wrist 16 is supported on the twist wrist I.15 so as to be pivotable about a fifth axis A5, and is driven to pivot by a fifth axis drive motor M5. The fifth axis A5 is provided in a direction inclined with respect to the fourth axis A4.

7 That Bendris? - 1 6 J-, swivel squirrel
17 is supported so as to be able to rotate around the sixth axis A6, and is driven to rotate by a sixth axis drive motor M6 (not shown). C) The axis A6 is provided in a direction inclined with respect to the fifth axis A5. On the swivel squirrel 1, 17, a floating cylinder arrangement 20 is attached (floated).

Each shaft drive motor M1-M6 is a pulse motor, and each is equipped with a pulse encoder E1-E6 for detecting {i'Z M.

Each of the motors M1 to M6 and pulse encoders E] to E6 are connected to and controlled by a robot controller 30.

FIG. 3 is a diagram showing the floating cylinder device 20. The floating cylinder device 20 has an air cylinder structure. A piston 22 is fitted into a cylinder body 21 fixed on a swivel wrist l7 of the robot 10, and a piston rod 23 is urged in a direction of retreating by compressed air. Inside the cylinder is a piston 22
A continuity sensor 24 is provided so as to be able to come into contact with. Continuity 8 The sensor 24 connects the piston 22 to the
It also serves as a floating cylinder device and detects electrical continuity through contact with the piston 22.
Detect the low end.

E is connected to the screw l/n mouth 23 via brackets 1 and 25.
A tool head 26 is attached. The tool head 26 is equipped with a tool 27 made of a four-wheeled grindstone.The cylinder body 21 is also provided with a distance sensor 28, and the tool head 26 is provided with a distance sensor 28.
The sliding amount of the floating cylinder device 20 is detected by detecting the distance from the piston 22 with light. is located at the end of the stroke that is pressed against the continuity sensor 24. When the tool (rotary grindstone) 27 is pressed against the work piece 50, the piston 22 and the piston IV rod 23 move against the urging force of compressed air. That is, the pressing force with which the tool 27 presses the abrasive material 50, which is the crop, is determined by the urging force of the compressed air.

FIG. 4 is a block diagram showing the robot control device 30. The control unit W 30 for the robot 1 includes a CPU 31 (central processing unit!ffi3), a memory 32, a C R 'l' console 33 that has a display and a keyboard integrated, and an operating box 3 that is a portable operation panel.
/1, and servo drive unit for each axis l-1) 1 to D
6, a programmable controller (PC) 36, and a tool drive unit 37.
NG determination time 1? It is equipped with three auxiliary control sections consisting of lt38.

The robot control unit 35 is a part that mainly controls the movement trajectory of the robots 1 to 1.
The teaching points taught by the J O G operation are stored in the memory 32, and based on the information, compensation calculations are performed to calculate interpolation points, which are stored in the memory 32. From this interpolation point, each axis J1 to Set the target position of J6 and set each axis servo drive unit T-1)]. -・1) 6 is the target position θ1, θ2...
・Shift the output of θ6. Servo drive unit for each axis
~D6 are each equipped with a CPU for servo control, and detect 10 position signals from pulse encoders E1~E6 to move to the commanded target position θ1 and θ6.
Each shaft drive motor M1 to M6 is controlled to achieve this.

The auxiliary control unit 39 includes a programmable controller I roller (P
c) Performs auxiliary control such as tool drive unit 36 and control of 37, as well as robot control C r) U
In other words, the NG discrimination circuit 38 sends and receives data to and from the floating cylinder device 20 according to the output from the distance sensor 28. It is determined whether or not it is within the threshold value, and a determination signal of NG, OK, or NG is output. I
'C36 secures an NG section storage area in its internal memory, and stores +NG for each section divided between the interpolation points.
, OK, -NG determination signals are stored. The section in which the robot 10 is currently running can be determined by input from the CPU 3.
The I'C 36 is informed by the section discrimination signal. End of run
Afterwards, the CPU 3 ] reads out the discrimination signal stored in the internal memory of the C 3 6 and performs processing such as correction of the motion locus.

Further, a signal from the continuity sensor 24 is also transmitted to the CPU 31 via the PC 36.

In this embodiment, the NG discrimination stage 1 is realized by the NG discrimination circuit 38, the teaching point storage means 2 and the NG section storage means 4.
is realized by the processing of the CPU 31 and the memory 32 of the robot control unit 35. Further, the traveling 1,000 steps 3, the modified 1,000 steps 5, and the repeating 1,000 steps 6 are realized by processing in the CPU 3 ].

The operation will be explained based on the configuration shown in -4- below.

FIG. 5 is a plan view (a), a physical view (b), and a cross-sectional view (c) showing a base material that is a workpiece. The base material 50 is a sheet metal member having a curved surface shape, and has a bead portion 51 formed by brazing welding. Cut this bead portion 51 with a tool (
By polishing using the rotating grindstone 27, the base material 50 is removed without causing distortion, and a smooth curved surface is obtained.

In order to teach the motion trajectory of the robot 10, the bead portion 51
Master base material 50 showing an ideal profile after removal of
Prepare. First, the machined surface 27 of the grindstone 27 is brought close to the master base material 50 without rotating the tool (rotary grindstone) 27.
A is brought into contact and the contact position is detected as the master base material position. Contact detection is performed by the continuity sensor 24. Measurement points 52 and 53 for contact detection are appropriately selected from the shape of the base material. Then, the checked master base material position is stored as a teaching point.

Next, arithmetic processing is performed to shift each teaching point by 1InII1 in the direction in which the floating cylinder device 20 is pushed. This is because the shape of the master base material is detected at the contact position of the cutting tool 27, but in order to apply a constant pressing force to the tool during sharpening work, the cutting cylinder device 20
is exactly 1. Is it mm? -) This is to determine a target motion trajectory so that the vehicle travels in a pushed-in state.

Next, based on the shifted teaching points, the teaching points are interpolated to find the interpolation point, and the robot (10) is actually run.
The degree of contact of the tool 27 with the master base material 50 is measured.

This is done by running the robot 10 with the tool 27 in contact with the master base material 50 without rotating it, and checking whether or not an NG signal from the NG discrimination path 38 is output for each section divided into each complementary point. This is done by memorizing the If even one NG signal is output in the section, the interpolation point is corrected to appropriately adjust the stroke amount of the floating cylinder W20, and the robot 1.0 is run again to insert the tool into the mask wire 50. Measure the degree of contact. By repeating traveling and correcting interpolation points many times, the stroke amount of the floating cylinder device 20 is reduced to 1 in the entire traveling section.
．． mm: l-0. Each interpolation point is modified to fall within the 1 mm threshold.

In this way, each teaching point giving the target motion trajectory is not simply a sampled point, but the continuous motion trajectory itself is automatically taught as a trajectory along the master base material 50.

FIGS. 6 and 7 are flowcharts showing processing in the CPU that realizes the above control idea.

When the teaching point measurement process is started (Step 100), first, the measurement points 52 and 53 of the base material 50 are positioned at a position where the measurement points 52 and 53 can be approached, and the posture is determined (Step 01).
. Next, the roach 14 starts roaching the base material 50 and waits for the crown tool 27 to come into contact with the base material 50 (
Steps 102 103). Contact with the base material 50 is detected when electrical continuity of the continuity sensor 24 is broken. Immediately after contact of the tool 27 with the aggregate 50 is detected, the robot 10 is stopped (step 1.04). The coordinates θ1, θ, . . . θ6 of each joint at that time are memorized to memorize the position of the contact point (step 105). By repeating the above process at each measurement point 5253 (step 106). The teaching point is stored as data consisting of a large number of contact point positions.

When contact detection for all measurement points is completed, step 10
Proceed to step 7 and set the teaching point consisting of the many contact point positions to 71.
1-Ting cylinder installation F? 2 Make a correction by shifting 0 in the direction of pushing 11. This completes the teaching point measurement process.

Next, the trajectory correction process shown in FIG. 7 is started.

Once the process is started (step 200), step 20
1, compensation calculations are performed between the measured teaching points, interpolation points are determined and stored in the memory 32, and the mouthbot 10 runs along a trajectory connecting the interpolation points. At this time,
The tool 27 is not rotated.

During this running operation, the CPU 3 1 successively outputs processing section discrimination signals to the PC 36 to inform it of which section the vehicle is currently running. The PC 36 receives 10 NG, OK, - from the NG discrimination circuit 38 for each section according to the processing section discrimination signal.
The NG signals are stored one after another in the internal memory.

When one cycle of running operation consisting of a series of running operations is completed, in step 202, the CPU 31 reads the internal memory of the PC 36 and checks whether there is a section in which ten NG signals or one NG signal are stored. If there is a section in which at least one NG signal is stored, the process proceeds from step 203 to step 204, in which the interpolation point of the section in which the NG signal is stored is corrected by a predetermined minute amount depending on whether it is 10 NG signals or 1 NG signal. Then, the process returns to step 201 and the running operation is repeated from the beginning.

If only the OK signal exists in all sections, the process advances from step 203 to step 205 and ends the process.

As explained above, in this embodiment, the tool 27 is directly connected to the base material 5.
0 to detect the teaching point, and move the tool 27 to 4U.
The target motion trajectory is traveled based on the interpolation points calculated from the teaching points while in contact with the material 50, and the interpolation points at the defective locations are corrected. For this reason, robot l-
1 to 10 can be automatically corrected, and the operating trajectories of the robots 1 to 10 that move by always applying the tool 27 to the base material 50 having a curvature at a constant angle can be set with an accuracy of ±0.1+Ilm. I was able to do that.

The application of the present invention is not limited to the robot 1 for polishing work. By applying it to a robot using a deburring force sensor, it is also possible to automatically set a motion trajectory with a constant pressing force.

"Effects of the Invention" The present invention has the above-mentioned configuration and is equipped with a means for correcting the teaching point by actually moving the robot, so that the contact of the tool with the workpiece having a curved surface is made appropriate. This has the excellent effect of being able to automatically teach the robot's motion trajectory with high precision using a small number of teaching points. Also, tools (
Since the rotary grindstone is brought into direct contact with the base material to detect the position of the base material and correct the target trajectory, it is possible to correct the wear of the grindstone at the same time.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a configuration diagram showing the structure of the invention, FIG. 2 is a perspective view showing the 0-bore, FIG. FIG. 5 is a block diagram showing the robot control device, FIG. 5 is a diagram showing the brushing material, and FIGS. 6 and 7 are flow charts showing the actual processing. 10. ．． ．． Robot, 20. ．． ．． Floating cylinder device, 24. ．． ．． Continuity sensor, 2 6
．． ．． ．． Tool head, 2 7. ．． ．． Tools (rotary abrasive:
I), 28. Distance sensor, 30. ．． ．． Robot control device, 31.
CPU, 35. ．． ．． Robot control unit, 3
6. PC (programmable controller), 38.
．． ．． NG discrimination circuit (N (E discrimination means), 3 9 ..
．． Auxiliary Control 18 Control Department, 5 0. ．． ．． Base material, 5 1. ．． Bead part, 5 2 5 3. ．． measurement point.

Claims (1)

[Claims] A floating cylinder device attached to the tip of a robot that biases and holds a tool in a certain direction with a predetermined pressing force, a distance sensor that detects the stroke amount of the floating cylinder device, and a distance sensor that detects the stroke amount of the floating cylinder device. NG determination means for determining from the output that the stroke amount has deviated from a predetermined target value by more than a predetermined threshold value and outputting an NG signal; a teaching point storage means for storing a target motion trajectory of the robot as a teaching point; and the teaching point. a traveling means for causing the robot to travel a target motion trajectory by interpolating between the teaching points, and each section divided by interpolation points obtained by interpolating between the teaching points to determine whether or not the NG signal is generated during the traveling. NG section storage means for storing the NG section for each section; correction means for correcting the teaching point so as to move the interpolation point of the section where the NG signal occurs in a direction to make the stroke amount appropriate; and the NG signal is generated at all the sections. 1. A robot control device comprising: repeating means for repeatedly executing the traveling means, the NG section storage means, and the correcting means until they no longer occur.