JPH0241843A - How to teach by tracing the work trajectory - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method of teaching an industrial Kawaguchi bot and a working machine to follow the work trajectory using a teaching playback method.
In particular, the present invention relates to a method of teaching by tracing a work trajectory suitable for reducing the burden on the operator required for teaching work.

[Conventional technology]

-iD The basics of the teaching playback method is to teach the robot in some way the procedure for the work you want the robot to do in advance. One of the contents of the teaching is position control information for each axis that determines the position and orientation of the work tool housed in the wrist of the robot Yl. As a method for teaching this position information, there is a tracing control method in which the work tool is moved along the work trajectory on the workpiece surface. There are two methods: teaching while holding the handle and moving the robot body directly, and controlling the robot body remotely using a teaching box or the like.

There is also an offline teaching method that uses a CAD computer, and a method that uses a three-dimensional shape measuring machine or the like to obtain data information about the shape of the workpiece and perform teaching.

[Problem to be solved by the invention]

In any of the conventional scanning teaching methods described above, the target position is taught by relying on human vision, so there is a problem in that it requires a great deal of effort and time for fine movement of the robot. In addition, the offline teaching method can shorten the teaching time by using CAD data, etc.
The data must be known information about the shape of the workpiece, and furthermore, errors between the known information and the actual shape of the workpiece cannot be avoided.

Even when obtaining workpiece shape data using a two-dimensional shape measuring machine or the like, if the measurement information is input as is, teaching data will be excessive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of teaching by tracing a work trajectory, which can reduce the burden on the operator required for teaching work and improve work efficiency.

[Means to solve the problem]

The above purpose is to provide a multi-axis force sensor that detects the reaction force applied to the work tool, and to measure the reaction force applied to the work tool at that time by using the point where the work tool first contacts the workpiece surface as the first reference point. It is detected by an axial force sensor, and the normal vector of the workpiece surface at the reference point is calculated from the force signal, and
The teaching data is stored in the storage device with the reference point as the teaching starting point, the work tool is moved a certain distance on the working trajectory in the tracing direction, and the workpiece surface vector at the contact point at that time is similarly calculated, and then the reference point is Calculate the angular difference between the workpiece surface vector direction at the point and the workpiece surface normal vector direction at the current contact point, and if the value is less than the preset angle, move the work tool again and change the workpiece surface normal vector direction in the same way. The angular difference in the vector direction is calculated, and if the angular difference in the vector direction normal to the work surface exceeds the set angle, the current contact point is set as a new reference point, and at least the new reference point is stored as the teaching point. This is achieved by a teaching method for tracing a work trajectory, which is characterized by storing the work trajectory in the device.

Here, if the angle difference in the direction of the work surface normal vector I - exceeds the set angle, if the contact point one before the new reference point is not the first reference point, the t previous contact point The teaching data is stored in the storage device using both the contact point and the new reference point as teaching points, and if the contact point is one point before the point or the first reference point, only the new reference point is stored. Teach data can be stored in a storage device as a teach point.

Further, if the angular difference in the normal vector direction of the workpiece surface exceeds the set angle, if the contact point one before the new store H (r point is not the first reference point and the one contact point before the new point If the angle difference between the workpiece surface vector direction of the new reference point and the workpiece surface normal vector direction of the new reference point exceeds the preset angle, both the previous contact point and the new reference point are used as the teaching point and the teaching data is is stored in the storage device, and in other cases, teaching data can be stored in the storage device with only the new reference point as the teaching point.

[Effect]

In the present invention configured as described above, if the angular difference between the workpiece surface vector direction of the first reference point and the workpiece surface normal vector direction at the current contact point exceeds a preset angle, the current contact point By using the new reference point as a new reference point and storing the teaching data in the storage device with at least the new reference point as the teaching point, the teaching point is automatically generated just by moving the work tool along the work trajectory, and the teaching operation is performed. can be done.

Therefore, there is no need to teach the target position by relying on human vision, and there is no need for an operation to store the teaching data, so the operator's labor and time required for teaching can be significantly reduced.

In addition, by storing teaching data in the storage device with both the contact point one before the new reference point and the new reference point as teaching points, the contact point one before the new reference point and the first reference point can be The contact points between the two are used as teaching points, and no teaching data is stored, so the number of teaching data can be reduced. Furthermore, for work trajectories that are straight or nearly straight from the first reference point to the contact point one before the new reference point, not only the new reference point but also the previous contact point is generated as a teaching point. A straight or nearly straight work trajectory can be taught accurately.

Note that if only the new reference point is used as a teaching point, the number of teaching data can be further reduced.

Furthermore, by determining whether the angular difference between the workpiece surface vector direction of the contact point one point before the new reference point and the workpiece surface normal vector direction of the new reference point exceeds a preset angle, It is possible to automatically determine whether the work trajectory from the point to the contact point one before the new reference point is a straight line or almost straight line, or a work trajectory with curvature or continuously changing.In the former case, the new standard The above-mentioned teaching method of storing the teaching data in the storage device with both the contact point one point before the new reference point and the new reference point as teaching points is carried out, and a straight line work trajectory from the new reference point to the contact point one point before the point is executed. In the latter case, by storing the teaching data in the storage device with only the new reference point as the teaching point, it is possible to avoid reducing the number of teaching data, and it is possible to use a teaching method suitable for each work trajectory. I can make a practical argument.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 4.

In FIG. 1, a robot 1 has a work tool 3 that moves over a workpiece 2 having an arbitrary curved surface shape, and the work tool 3 has a multi-axial force that detects the force applied to the work tool 3. Sensor 4 is installed. The robot 1 operates according to control signals output from the controller 5. The controller 5 has a storage device 6 as an external memory, and information is transmitted from a teaching box 7 operated by an operator to the controller 17-5 to control the robot 1. The controller 5 creates a control signal to be output to the robot 1 according to a preset program based on the information obtained from the teaching box 7 and the information obtained from the multi-axis force sensor 4 and the robot soto 1. Calculates teaching data. The teaching data is stored in W
6. In addition, the controller 5 has internal memory,
As shown in FIG.
It has a data memory area 5b and a second data memory area 5C.

Next, a working locus tracing teaching method according to an embodiment of the present invention, which is performed using the above-described apparatus, will be further described with reference to FIGS. 3 and 4. FIG. 3 is a flowchart showing the control procedure of the program set in the controller 5, and FIG. 4 shows a cross section of the work trajectory taught by this embodiment, with the tracing direction of the work trajectory taken as the X axis. In parallel, the direction of pressing of the working tool is parallel to the two axes.

First, before starting the teaching work, the memory areas 5a, 5b, 5c of the controller 5 and the memory of the storage device 6 are initialized (step 10).

Move the work tool 3 to the point PO on the work surface and move the work tool 3 to the point PO on the work surface.
(Step 11), the force applied to the work tool 3 is detected by the multi-axis force sensor 4, and the workpiece surface normal vector NO at point PO is calculated from the force signal (Step 1).
2). This calculation is performed, for example, by unitizing the force vector, since the direction of the force detected by the force sensor 4 approximately coincides with the direction of the workpiece surface normal vector NO. Then, store the teaching data in a memory bag with point PO as the teaching starting point! 6, and also stores No data in the reference point data memory area 5a with point PO as the first reference point (step 13).

Next, the work tool 3 is moved in the tracing direction on the work trajectory by a preset distance Δ'' (step 14), the workpiece surface normal vector N1 at the next contact point P1 is calculated, and the reference point PO The direction angle difference α between the normal vector No. of the workpiece surface and the workpiece surface normal vector No. is calculated (step 15). Next, it is determined whether the angle difference α exceeds a preset angle (step 16). Here, assuming that the angle difference α is less than or equal to the set angle, the teaching data at the contact point P1 is
data memory area" or 5b (step 17), and moves again by Δ to the next contact point P2 (step 14).
). Thereafter, the work tool 3 is moved on the work trajectory until the angle difference α exceeds the set angle.

At this time, the data stored in the first data memory area 5b will be transferred to the second data memory area 5c when the data is imported next time.
The data stored in the second data area 5C is sequentially erased (step 17).

At the contact point Pl, if the direction angle difference α between the work surface normal vectors Nn+ and No exceeds the set angle, it is assumed that Pn-1 from the contact point PO on the work trajectory is a straight line or almost a straight line, After determining whether the contact point Pl-1 matches the first reference point PO (step 18), if they do not match, the point Pn+-1 is set as the teaching point (step 19), and the first The teaching data stored in the data memory area 5b is stored in the teaching data storage device 6 (one step). If the contact point P n-1 coincides with the reference point PO, the teaching data at the point P n-1 is stored. Since the teaching data has already been stored in the storage device 6, it is not stored at this point, and the contact point Pm is generated as a teaching point and the teaching data is stored in the teaching data storage device 6.Step 19.
20), the contact point Pm is set as a new reference point and the data of the workpiece surface normal vector Nn is stored in the reference point data memory area 5a (step 21). At this time, the first reference point PO
The data of the workpiece surface normal force vector NO is deleted from the reference point data memory area 15a.

Repeat the above operations until the end point of the work trajectory (step 22)
, the contact point at the end point is set as the end point of the tracing teaching, the teaching data is stored (step 23), and the tracing teaching operation is completed.

In this way, in this embodiment, by simply moving the work tool 3 along the work trajectory, the workpiece surface vector NO at the first reference point PO and the workpiece surface vector N at the contact point PI are
If the directional angle difference α exceeds the set angle, the teaching point P
Since n-1 and Pi or the teaching point PI are automatically generated and the teaching data is stored, there is no need to teach the target position by relying on human vision, and there is no need for an operation to store the teaching data. This can significantly reduce the labor involved.

Furthermore, the time required for teaching can be reduced. In addition, the contact point between the first reference point PO and the last contact point Pn-1, where the direction angle difference α between the workpiece surface normal vector N0 does not exceed the set angle, is not used as a teaching point, and the teaching data is Since it is not stored, the number of teaching data can be minimized.

Furthermore, in this embodiment, the first reference point PO and the contact point P n
-1, the previous contact point Pm-1 is generated as a teaching point as well as the new reference point Pl. A straight line or nearly a straight line between the lines can be taught accurately.

Although the above explanation was two-dimensional, this embodiment can be similarly applied even if the workpiece surface has a three-dimensional shape. This will be explained with reference to FIG.

In FIG. 5, the work locus indicated by a broken line is a straight line parallel to the X-axis, or the workpiece surface is inclined about the axis of the work locus along the way. In this case, when the workpiece surface normal vector Nrg at the contact point Pm and the workpiece surface normal vector NO at the first contact point PO are projected onto the x-z plane, the direction angle difference becomes 0, or when projected onto the y-z plane, There will be a difference in direction and angle. Therefore, by calculating the solid angle difference between the work surface normal vectors NO and Nl as the directional angle difference, the teaching data can be stored in the storage device 6 with the point Pm as the new reference point in the same way as described above.

Another embodiment of the invention will be described with reference to FIGS. 6 and 7.

In the L-recording example, in order to accurately teach a straight or nearly straight work trajectory between point PO and point Pn-1, as described above, the new reference point Pn+ and the previous contact point Pn -1 were generated as teaching points. However, in the case of a curved surface where the workpiece surface shape has no such straight line or almost straight line part in the work trajectory and whose curvature changes relatively continuously,
It is not necessary to generate the contact point P l-1 immediately before the new reference point P1 as a teaching point, and it is sufficient to use only the new reference point Pm as a teaching point.

FIGS. 6 and 7 show an embodiment incorporating this idea.

That is, the surface shape of the workpiece, which is the target of the scanning teaching method of this embodiment, has a curvature that continuously changes as shown in FIG. When teaching the workpiece surface in this way, as shown in FIG. directly generates only the contact point Pli as a teaching point and stores the teaching data in the teaching data storage device 6 (Step 19), and sets the contact point P1 as a new reference point P.
Store the data of the workpiece surface normal vector Nrm as O in the reference point data memory area 5a (step 21);
The teaching operation other than this is the same as the embodiment shown in FIG.

According to this embodiment, it is possible to perform copying teaching with a smaller number of teaching points than in the embodiment shown in FIG. 1, which has the effect that the number of teaching data can be further reduced.

A further embodiment of the pond according to the present invention will be described with reference to FIGS. 8 and 9.

As described above, the embodiment shown in FIG. 7 can be applied when the curvature of the workpiece surface changes continuously, but for this purpose, the shape of the workpiece surface must be known in advance. Further, depending on the workpiece, the workpiece may have both a straight or nearly straight working trajectory and a working trajectory in which the curvature changes continuously. Therefore, it would be convenient if the teaching operation could be performed while automatically determining which category the workpiece surface shape belongs to. FIGS. 8 and 9 show such an embodiment.

That is, in FIGS. 8(a) and 9, the direction angle difference α between the workpiece surface normal vector Nll1 and NO at the contact point Pm
If it is determined that the angle exceeds the set angle (step 1
6), further calculate the workpiece surface normal vector j·le Nl-1 of the contact point Pl-1 immediately before the contact point Pra, and calculate the workpiece surface normal of the contact point Pl shown in FIG. 8(b). Vector N1
1 and the workpiece surface vector N t-1 of the contact point P l-1
Step 18A1 Next, it is determined whether the angular difference α° exceeds a preset angle (Step 18B). Here, if the angular difference α° is less than the set angle, the first Considering that the angular difference α that exceeds the set angle of the work surface normal vector NO, Nn between the reference point PO and the contact point P1m does not occur between the contact points Pn-1 and Pm, It is assumed that the curvature is continuously changing between , and the teaching data is stored in the storage device 6 with only the point PI as the teaching point (step 20). If the angular difference α exceeds the set angle considers that the angular difference α that exceeds the set angle of the work surface normal vector No, Nl between the first reference point PO and the contact point Pm occurs between the contact point P n-1 and PI, and from the point PO to the point After assuming that the line up to P l-1 is a straight line or almost a straight line, and determining whether or not the contact point P l-1 coincides with the first base point PO (step 18
), if they do not match, the teaching data is stored in the storage device 6 with both point P I-1 and point Pl as teaching points (one step). The subsequent steps are the same as in the embodiment shown in FIG.

In this way, in this embodiment, even if the workpiece surface shape is not known in advance, or even if the workpiece surface shape has a mixture of straight lines and curves, the shape of the workpiece trajectory is automatically determined and the first It is possible to implement a teaching method suitable for the work trajectory of either the embodiment shown in the figure or the embodiment shown in FIG.

Note that in the same way as explained with reference to FIG. 5, in the embodiments shown in FIGS. 6 and 7 and the embodiments shown in FIGS. 8 and 9, the work surface has a three-dimensional shape. It is applicable even if you have.

In addition, in the following embodiments, the calculation of the workpiece surface normal vector NO is performed by assuming that the direction of the force detected by the force sensor 4 almost coincides with the direction of the workpiece surface normal vector NO, and using the force vector as a unit. It was done by making
When the work tool comes into contact with the workpiece, there is an effect of frictional force,
Since the direction of the force detected by the force sensor 4 may not exactly match the direction of the workpiece surface normal vector NO,
In order to calculate a more accurate workpiece surface normal vector NO, the influence of frictional force may be removed. For example, there is a method of correcting the direction of the force detected by the force sensor by assuming a constant dynamic friction coefficient. The effect of frictional force can also be eliminated by making the working tool itself out of a glove with low friction.

〔effect〕

According to the present invention, teaching points are automatically generated and teaching operations can be performed simply by moving the work tool along the working trajectory, thereby significantly reducing the operator's labor and time required for teaching. Can be shortened.

Also, if the teaching data is stored in the storage device with both the contact point before the new reference point and the new reference point as teaching points,
It is possible to do this without reducing the number of teaching data, and to accurately teach a straight or nearly straight work trajectory.

Furthermore, when determining whether the angular difference between the workpiece surface vector direction of the contact point one before the new reference point and the workpiece surface normal vector direction of the new reference point exceeds a preset angle, it is necessary to It is possible to automatically determine whether the work trajectory is a straight line or a work trajectory with continuously changing curvature, and to perform teaching operations suitable for each.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram w1 showing an apparatus for carrying out a working locus tracing teaching method according to an embodiment of the present invention;
The figure is a schematic diagram showing the memory area and teaching data storage device of the controller of the device, FIG. 3 is a flowchart showing the copying teaching method, and FIG. 4 is a work trajectory for explaining the copying teaching method. FIG. 5 is an explanatory diagram when the same tracing teaching method is applied to a three-dimensionally changing workpiece surface, and FIG. FIG. 7 is a sectional view of a work trajectory for explaining the teaching method, and FIG. 7 is a flowchart showing the tracing teaching method, and FIG. 8(a) and FIG.
b) is a sectional view of a work trajectory for explaining a teaching method for tracing a work trajectory according to still another embodiment of the present invention;
FIG. 9 is a flowchart showing the tracing teaching method. Explanation of symbols■...Robot 2...Workpiece 3...Work tool 4...Multi-axis force sensor 5...Controller 6...Storage device Fig. 1

Claims (3)

[Claims] (1) A multi-axis force sensor that detects the reaction force applied to the work tool is provided, and the point where the work tool first contacts the workpiece surface is used as the first reference point, and the reaction force applied to the work tool at that time is measured by the multi-axis force sensor. Detected by a force sensor, the workpiece surface normal vector at the reference point is calculated from the force signal, the teaching data is stored in the storage device with the reference point as the teaching start point, and the work tool is moved in the tracing direction on the work trajectory. After moving by a certain amount and calculating the workpiece surface vector at the contact point in the same way, calculate the angular difference between the workpiece surface vector direction at the reference point and the workpiece surface normal vector direction at the current contact point. If the value is less than the preset angle, move the work tool again and calculate the angular difference in the direction of the workpiece surface normal vector in the same way, and if the angular difference in the direction of the workpiece surface normal vector exceeds the set angle. If the current contact point is a new reference point, the teaching data is stored in a storage device using at least the new reference point as a teaching point. (2) If the angular difference in the normal vector direction of the workpiece surface exceeds the set angle, if the contact point one before the new reference point is not the first reference point, the contact point one before the new reference point. The teaching data is stored in the storage device with both the new reference point and the new reference point as the teaching point, and if the contact point one before the new reference point is the first reference point, the teaching data is stored with only the new reference point as the teaching point. 2. The method for teaching tracing of a work trajectory according to claim 1, wherein the method is stored in a storage device. (3) If the angular difference in the normal vector direction of the workpiece surface exceeds the set angle, the contact point one before the new reference point is not the first reference point and If the angular difference between the workpiece surface vector direction and the workpiece surface normal vector direction of the new reference point exceeds the preset angle, the teaching data will be set using both the previous contact point and the new reference point as the teaching point. 2. The work locus tracing teaching method according to claim 1, wherein the teaching data is stored in a storage device, and in other cases, the teaching data is stored in the storage device using only the new reference point as a teaching point.