JPS62242201A - Controlling method for industrial robot - Google Patents

Abstract

PURPOSE:To accurately perform high precision work by correcting each acting course position according to the amount of flexure of moving parts at the time of teaching, correcting halfway course position at the time of reproduction according to the amount of flexure of the moving parts, and correcting acting course position again when moving to the next acting course position. CONSTITUTION:Angle of flexure DELTAtheta, DELTApsi of the first and second arms 3, 5 are calculated respectively for each acting course position at the time of teaching, and each acting course position is corrected according to calculated angles of flexure DELTAtheta, DELTApsi. At the time of reproduction, a predetermined halfway course position is determined from the corrected acting course position and acting course position to be moved next, and angles of flexure DELTAtheta, DELTApsi of the first and second arms 3, 5 are calculated at each halfway course position, and respective halfway course position is corrected according to the calculated angles of flexure DELTAtheta, DELTApsi. The next acting course position is further corrected according to the calculated amounts of flexure at the time of shifting from the final position of corrected halfway course position to the next acting course position and moved to corrected acting course position.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the control force "a" of an industrial robot that controls the movement of a motion part according to a pre-stored motion path position, and in particular improves the accuracy of the motion path. This invention relates to a control method suitable for improving the control method.

[Conventional technology]

Conventional industrial robots are configured to sequentially memorize the path positions on which the robot should move during teaching, and to control the movement of the robot in accordance with the memorized movement path positions when regenerating the robot.

However, in such industrial robots, the operating parts are considered and controlled as being completely rigid, so in each operating path, the position command value commanded at the time of teaching and the position command value read from the position detector at the time of regeneration are Even if the calculated target value matches, as shown in FIG. 5, the operating part 5 is deflected by the weight, so the control point S' is the position where the control is performed while the deflection actually occurs. There is a problem that the controlled point S, which is the position that should originally be controlled, does not match.

To solve this problem, there is a known technique disclosed in Japanese Patent Publication No. 53-44746, for example. This known technique is configured so that the position command value and the target value match at each motion path position, and furthermore, the actual control point S' and the controlled point S match at the time of regeneration.

[Problem that the invention seeks to solve]

By the way, in the above-mentioned conventional technology, although the control point S' and the controlled point S match at each movement path position, the control point S' and the controlled point S at the intermediate path position match between each movement path position. There is an error in this. That is, there is an error on the interpolation path.

If there is an error in such an interpolation path, there is a problem in that it is difficult to accurately perform operations that require precision, such as welding, sealing, painting, etc.

The object of the present invention is to solve the problems of the prior art described above.

An object of the present invention is to provide a control method for an industrial robot that can improve the accuracy of interpolation paths and perform high-precision work accurately.

[Means for solving problems]

In the present invention, the amount of deflection of the operating portion is calculated in advance for each stored motion path position, and each motion path position is corrected in accordance with the deflection amount.

When regenerating, the amount of deflection of the operating part at that position and the position to be re-corrected according to the amount of deflection are calculated at the corrected movement path position, which is the corrected initial position, and the correction is made to this re-corrected movement path position. do.

Next, predetermined intermediate route positions are determined from the distance between the re-correction operation route position and the next correction operation route position, and for each intermediate route position, the amount of deflection of the operating part at that position and the A position to be corrected is calculated according to the amount of deflection, and the operating section is sequentially interpolated and moved to the corrected intermediate path position.

Thereafter, at the time of moving from the corrected intermediate path position, which is the corrected final position, to the corrected movement path position to be moved to the corrected movement path position, re-correction is made according to the amount of deflection of the operating part at that corrected movement path position and the amount of deflection. The operating section is then moved to this re-corrected operating path position.

Then, the processing of interpolation movement of the operating section and the processing of movement of the re-corrected operating path position are sequentially repeated until the operating section reaches the final operating path position.

[Effect]

In the present invention, each movement path position is corrected according to the amount of deflection during teaching, and when regenerating, the initial corrected movement path position is re-corrected according to the amount of deflection, so that the movement path position is adjusted to this re-corrected movement path position. The positioning of the parts can be controlled. Furthermore, when moving from the initial re-correction movement path position to the next correction movement path position, the intermediate path position between the two is calculated, and each intermediate path position is corrected to the correction path position according to the amount of deflection. Actual control points and controlled points on the interpolation path can be matched.

Furthermore, when moving from the correction intermediate path position of the final position to the next correction operation path position, the operating part is moved to this re-correction operation path position after the correction operation, so even when moving from the interpolation path to the operation path, the control point The controlled point can be matched with the controlled point. Therefore.

As a result, the operating part can be moved with high precision not only on the operating path but also on the interpolation path, especially for welding.

Works that require interpolated path accuracy, such as sealing, painting, etc., can be performed accurately.

〔Example〕

An embodiment of the present invention will be described below with reference to the accompanying drawings. 1st
- The figure is an overall view of an articulated robot to which the method of the present invention is applied, Figure 2 is an explanatory diagram of deflection in the articulated robot, and Figure 3 is an illustration of deflection in the articulated robot.
FIG. 4 is a flowchart showing an embodiment of the method of the present invention.

In the articulated robot to which the method of the present invention is applied, the swivel table has a swivel axis 1 that rotates vertically, a first arm 3 is attached to the swivel table via a first rotation axis 2, and the first arm 3 A second arm 5 is attached to the tip of the rotating shaft 4 via the second rotating shaft 4, and the first arm 3 is located at the center position O of the first rotating shaft 2.
The second arm 5 rotates around the second rotation axis 4.
It is configured to rotate around the center position o2.

In the articulated robot configured in this way, since the weight acts on each of the first and second arms 3 and 5, the eleventh and second arms 3 and 5 are bent. Specifically, the second arm 5 is affected by the total weight of the second arm 5, that is, the weight of the second arm 5 and the weight of the workpiece to be attached to it, so as shown in FIG. Six deflection angles corresponding to the weight are generated with respect to the line 6. On the other hand, the fjSl arm 3 is affected by the full weight of the second arm 5 in addition to its own weight, so as shown in FIG. 7, a deflection angle Δ0 corresponding to its weight occurs. Note that the deflection angle Δθ is the first
As shown in the figure, the reference line 7 of the first arm 3 is at an angle O with respect to the vertical line This is the case where the reference line 6 of the angle P is the angle P, and these deflection angles Δ0.
The Δdoors differ depending on the angles of the first and second arms 3 and 5, respectively.

Therefore, in the method of the present invention, first, when teaching each motion path position at the time of teaching, the first . The deflection angles Δ0°ΔP of the 27th beams 3 and 5 are calculated, and the respective operating path positions are corrected according to the calculated deflection angles of 6096.

The deflection angles Δθ and Δdoor are calculated by adding the bending moment of the first arm 3's own weight to W, LG, the bending moment of the second arm 5's own weight to W2LG2, and the weight of the workpiece to the dead weight of the second arm 5. The total weight of 27-45, which is the value, is Ml, the work weight is Ml, the length of 17-43 is L+, the length of second arm 5 is L2, the spring constant of first arm 3 is, 2
If the spring constant of arm 5 is Kz, it can be obtained from the following formula.

Furthermore, in the method of the present invention, when regenerating, a predetermined intermediate route position is determined from between the corrected operation route position and the next operation route position to be moved, and the first . Calculate 〇 and ΔP to the deflection angles of the second arms 3 and 5, respectively, and calculate the calculated deflection angle ΔO28? Each intermediate route position is corrected according to the calculated deflection amount, and when moving from the final position of the corrected intermediate route position to the next operation route position, the next operation route position is further corrected according to the calculated deflection amount. Then, it is moved to the corrected movement path position.

Next, an embodiment of the method of the present invention will be described in detail with reference to FIGS. 3 and 4.

When teaching, first input the workpiece weight M2.SL
), then the angle ε of the teaching point which is the initial motion path position,
θ and p are detected (s2). This is detected by the position detector. It is obtained by detecting the angle of the second drive shafts 2 and 4.

And the first. Deflection angle Δθ of each of second arms 3 and 5
, ΔP are calculated using equation (I) (s3).

Note that in equation (I), W, LG, , W2LG2, and LlyL2 are set in advance, and the weight scale is determined based on the input Ml.

Deflection angle Δ0. After calculating ΔAshi, the first. The angle of the second drive shaft 2°4 (θ
', r'), that is, the first. The corrected positions of the second arms 3 and 5 are determined (s4).

As a result, each motion path position is corrected as a corrected motion path position.

After the correction, the orthogonal coordinates of the control point S are calculated from the following equation (3) (S5), and this value is stored as teaching data (S6).

Note that the reason for executing the process in S5 is that the articulated robot has a joint coordinate format that is controlled by the rotation angle of the drive shaft, so it is necessary to convert the joint coordinates to Cartesian coordinates. It's for a reason.

After that, it is determined whether all teaching processing has been completed (S7
), if the process is not completed, the processes from S2 onwards are repeatedly executed until the process is completed.

As a result, each correction operation path position is corrected in consideration of the deflection angle.

On the other hand, during regeneration, as shown in Figure 4(a),
First, after the workpiece weight M2 is input (S8), teaching data between two adjacent points along the moving direction is obtained. That is,
The distance between two points A and B between the first teaching data and the next teaching data stored at the time of teaching is calculated (S9).

Here, the first teaching data A is (X++ yI+ z+
), and the next teaching data B is (X2+yZ+22), then the distance can be found from the following equation (4).

L= JCx+ xz)'+(y+ yz)'+(
zl-zz)' (4) That is, the distance between the initial correction movement path position A and the correction movement path position B to be moved next is determined from equation (4).

Next, the number n of commands for intermediate route positions is calculated from the distance. For example, assuming that the command value of the robot is commanded once every m seconds and the moving speed is V, the number of commands n between the teaching data A and B can be determined from the following equation (5).

As a result, the route position along the way can be determined from the distance between the two points A and B.

Then, after setting the counter (Sll), the orthogonal coordinates to the initial intermediate route position are calculated (812).

This is inversely transformed to create the rotation axis and the first. The angle of the second drive shaft is determined (S13). This is shown in equation (6).

K1=K,"+Z" K4=JKx
x, 20H': x≧013'≧0→O X≧0 + y < O→π xku0. y〉0→O x < O* y < O→π ・The first. Second drive shaft 2゜4
is the angle of the first intermediate route position, for example, the second
The arm 5 is at the control point S' as shown in FIG.

However, since the position of point S' is considered to be completely rigid, it differs from the controlled point S that is actually controlled when the deflection angle of the second arm 5 is taken into account. Therefore, the first step is the first step. Deflection angle Δ03 at the intermediate path position of the second arms 3 and 5. ΔPi is determined (S14), and this deflection angle Δ03
．． Δdoor, according to the 1° angle of the second drive shaft 2.5 'i,
Calculate Oi and Pi (S tS).

In this case, the deflection angle Δ01. Δr is found from the above equation (I), and the angle εi+J+Pi is found from the following equation (7).

Then, after S15, count +1 (516), S
1 according to the angle calculated in step 15. Second drive shaft 2.5
is commanded and driven (S17). Thereby, from the initial re-correction operation path position P1 to the initial correction intermediate path position ε2.
Rotating axis 1 and 1st and 2nd arms 3 and 5 at θ+yPi
moves.

Furthermore, after S17, it is determined whether the predetermined number of times has been reached, and when the predetermined number of times has been reached, the process moves to the next process, and if the predetermined number of times has not been reached, the processes from S12 onwards are repeatedly executed. As a result, the first . second arm 3,
Since the position No. 5 is corrected, it becomes the corrected intermediate route position.

After that, the teaching point B to be moved next is read out and inversely transformed, and the first . Calculating the angle εBe OBs PB of the second drive shafts 2, 4, the first . Deflection angle ΔOB of second arms 3 and 5
Calculate tΔ9'n520), the deflection angles ΔOB, Δ
The pivot axis 1 and the 1st . Calculate the angle εB+ OBs Pa of the second drive shafts 2, 4 (521), and calculate the angle ε[1+ OBs PB of the rotation axis 1 and the first drive shaft 521).
The second drive shafts 2 and 4 are controlled (S22).

As a result, when moving from the final correction intermediate path position to the correction movement path position B between the two movement path positions A and B, the deflection angle ΔO at the correction movement path position B
Since the motion path position is re-corrected in consideration of BtΔPB,
At this re-corrected motion path position B, the swivel base and the first. Movement of the second arms 3 and 5 is controlled.

And the first. The processes from S2 onwards are sequentially repeated until the second arms 3, 5 reach the final position of the movement path. (S23).

Therefore, at the time of regeneration, the actual control point S' at each operation path position A to P matches the controlled point S, and the actual control point S at an intermediate path position between each operation path position and the controlled point S', the motion path and interpolation path can be made highly accurate.

As a result, operations that require interpolation path accuracy, such as welding, sealing, painting, etc., can be performed accurately.

In addition, when the workpiece weight M2 is input when it is possible,
Each intermediate route position is corrected according to the deflection angle based on the input workpiece weight M2.

Since the actual control point S' and the controlled point S always match, if the workpiece weight M2 is different from that at the time of teaching, that is, the weight of the welding torch, the weight of the sealing torch, and the weight of the painting gun are Even if the movement path position and the intermediate path position change, the positions of the movement path position and the intermediate path position are always constant, so that no teaching is required.

〔Effect of the invention〕

As described above, the method of the present invention can be used at the time of teaching.

Each movement path position is corrected according to the amount of deflection of the movement part, and when regenerating, each intermediate path position found between the corrected movement path position and the movement path position to be moved next is calculated. , is corrected according to the amount of deflection of the operating part, and when moving from the corrected final intermediate route position at that operating route position to the next operating route position, the operating route position is corrected again to create this corrected operating route. Since the movement of the operating unit is controlled according to the position, the operating path and the interpolation path can be made highly accurate, and as a result, work requiring interpolation path accuracy can be performed accurately.

[Brief explanation of drawings]

FIG. 1 is an overall view showing an articulated robot to which the method of the present invention is applied; FIG. 2 is an explanatory diagram of deflection in the articulated robot;
FIG. 3 is a flowchart at the time of teaching showing an embodiment of the method of the present invention, FIGS. 4(a) and (b) are flowcharts at the time of regeneration, and FIG. 5 is an explanation of the relationship between control points and controlled points. It is a diagram. 1... Swivel base, 2... First drive shaft, 3... First
Arm, 4... Second drive shaft, 5... Second arm, ΔO... Deflection angle of first arm, Δr... Deflection angle of second arm. Representative Patent Attorney Tadashi Akimoto Figure 2, Figure 3

Claims (1)

[Scope of Claims] 1. A method for controlling an industrial robot, which sequentially stores path positions along which the movement section should move during teaching, and controls the movement of the movement section according to the stored movement path positions during regeneration. (I) At the time of teaching, calculate the amount of deflection of the operating part at each of the memorized motion path positions at that position, and correct each motion path position according to the amount of deflection, (II ) At the time of regeneration, at the corrected operation path position which is the corrected initial position, calculate the amount of deflection of the operating part at that position and the position to be re-corrected according to the amount of deflection, and correct to this re-corrected operation path position. (III) Determine each predetermined intermediate route position from the distance between the re-correction operation route position and the next correction operation route position, and calculate the operation unit at that position for each intermediate route position. (IV) After calculating the amount of deflection of At the time of moving to the corrected motion path position to be moved next, calculate the amount of deflection of the moving part at that corrected motion path position and the position to be re-corrected according to the deflection amount, and move the moving part to this re-corrected motion path position. (V) A method for controlling an industrial robot, characterized in that the steps (III) and (IV) are sequentially repeated until the operating section reaches the final operating path position.