JPH06149344A - Robot control method - Google Patents

Abstract

PURPOSE:To provide a robot control method which can handle a robot with a high degree of coincidence with the desired contents by teaching the robot the change-with-time data on the position of a tool tip point against a specific part of the robot that has the fixed relation with a carried subject. CONSTITUTION:A cylindrical work W is fixedly held against an arm which can rotate around an axis passing the final wrist point H. Meanwhile three fixed points T1, T2 and T3 set by the movements of a torch T are fixedly held, and the points set on a welding line I successively arrive at a position close to or coincident with the point T1. Thus the arc welding treatment is carried out. Under such conditions, the points T1-T3 are set as the tool tip points respectively and the calculating method acquired based on these tip points is previously stored in a robot controller. Then the position data on a key point hand coordinate system SIGMAH are taught to a robot together with the change with time. Thus the teaching jobs of the robot are possible when the data coupled directly to the actual images of the job contents are designated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a robot for industrial use, and more specifically, it is of a type for controlling the position and posture of a work with respect to a tool fixed at a fixed position in a work space. The present invention relates to a robot control method that is particularly useful when using a robot for an application.

[0002]

2. Description of the Related Art Conventionally, when a robot is used for an application of a type in which a position and a posture of a work are controlled with respect to a tool fixed at a fixed position in a work space, such as a handling type arc welding work. , The robot is taught by using a specific point of the work held by the robot hand as the tool tip point.

That is, with respect to the change with time of the position and posture of a work to be taken with respect to a fixed tool, several position data regarding a specific point on the work are taught as teaching point data, and between the teaching points. Specify the speed of the robot,
It was customary to determine the position and orientation by an interpolation method.

In other words, data of a fixed point on the base coordinate system defined in relation to the fixedly arranged tool is taught to the robot as tool tip point data, and based on this, data of the workpiece gripped by the robot hand is taught. A method of controlling the motion of the robot in a manner that determines the change in position and posture over time has not been adopted.

[0005]

Problems of the prior art will be described with reference to FIGS. 1 and 2 which conceptually show an example of using a robot for handling welding. In FIG. 1, R is a robot and W is a cylindrical workpiece designated by a robot hand. The robot R has a rotation pair 1, a translation pair 2, and the like, and the final wrist point is indicated by the symbol H. Between the translational even number 2 and the final wrist point, an appropriate number of unillustrated pairs are present, and the robot R as a whole has six axes of freedom of movement.

A cylindrical work W having J as an axis is fixedly gripped in an illustrated posture with respect to an arm rotatable about an axis passing through a final wrist point H. T is a torch for sequentially performing arc welding along the welding line I on the outer peripheral surface of the work W, T1 is a specific position near the tip of the torch (supply wire), T2 is the base of the torch, and T3 is the torch. A fixed point (representative point) corresponding to the rotational position around the axis of the torch is located at a specific position off the axis of.

ΣH = H-xyz represents a hand coordinate system, which is a three-dimensional orthogonal coordinate system with the final wrist point H as the origin. This coordinate system is a coordinate system that moves integrally with the final arm G. The final arm G and the y-axis are parallel to each other, and the central axis J and the x-axis of the work W are also parallel to each other.

On the other hand, ΣB = O-XYZ is a base coordinate system whose origin is the installation position O of the robot R, and is set as an absolute coordinate system in the work space. This coordinate system is also a three-dimensional orthogonal coordinate system.

When performing arc welding by the handling method, three fixed points T1, T2, T associated with the torch are used.
3 is kept immobile, and the points on the welding line L successively reach the position close to or facing T1 and arc welding is performed. That is, the points T1, T2 and T3 are fixed points on the base coordinate system ΣB, but the hand coordinate system Σ
It becomes a fixed point on H.

In the course of the welding process along the welding line I, the angle Ψ of the torch T with respect to the outer peripheral surface of the work W.
(There are three degrees of freedom including the twist angle of the work with respect to the axis of the torch), that is, the relative attitude of the work W with respect to the torch T is also controlled at the same time, and is generally changed sequentially.

When controlling the motion of the robot to realize such movement of the work W, in the conventional method, a fixed point P is set on the work W and the point P is a so-called tool tip point (tool point, tool point). , A gripping point or a handling center point), teaches an appropriate number of teaching point data for this tool tip point P, interpolates the position and orientation between the teaching points, and further A method of designating the P point as the displacement speed of the posture has also been adopted. Contrary to the point T1, the point P is a fixed point on the hand coordinate system ΣH and a moving point on the base coordinate system ΣB.

Therefore, the teaching of the motion to the robot is performed in the form of teaching the position / orientation on the base coordinate system with respect to the tool coordinate system having the point P and the point P as the origin.

However, since the relative position between the working point close to the point T1 and the tool tip point P changes as the welding process progresses, the robot is controlled so as to realize a desired and proper welding process. Was actually difficult. Particularly, it is not easy to stably realize a desired value for the moving speed of the processing point.

The reason will be briefly described with reference to FIG. FIG. 2 is a diagram showing a change in the position-posture relationship between the work and the torch in FIG. 1 as seen from the direction of the axis J. The work indicated by W at a certain time t is a time after a lapse of some time. At t ′, a case is shown in which robot control is required so as to change to the state indicated by W ′ as the welding process progresses.

That is, at the time t, the ◯ mark portion of the work is being welded at the position Q, and the X mark portion at the position Q ′ close to the ◯ mark portion is in an unmachined state. It is assumed that the torch T is required to have an angle close to a right angle with respect to the surface of the work as shown in the figure. Then, from this state, while gradually letting the torch T relatively lie, the machining point is moved toward the x-marked portion at a constant speed v along the circumferential direction of the work, and at time t ′, the welding of the x-marked portion is performed. Assume a case where it is required to execute in the state as shown at the point Q.

Since the torch T is immovable (on the base coordinate system), in order to meet such a request, the workpiece is rotated about the machining point (as viewed on the base coordinate system) while being rotated. It is necessary to make a motion such that a slight translational motion is superimposed on it. In order to achieve the robot control that realizes this movement by the conventional method, it is necessary to teach the data for realizing the movement that matches the tool tip point P.

Here, if the tool tip point is present at a position close to the processed portion (o, x portions) in FIG. 2 from time t to t ', the moving direction and moving speed of the point P are relatively large. Although similar, the moving direction of the point P (P → P ′) and the moving speed (distance between PP ′) are generally in the moving direction of the processing point (Q ′ → Q or Q → Q ″) and moving speed v (Q′Q or QQ ″)
(Distance)) is completely different.

Moreover, when the machining point moves along the circumferential direction as in this example, the positional relationship between the machining point and the point P also largely changes. Therefore, the difference in the direction and speed is not constant at all. This tendency becomes even more pronounced when the work is twisted around the torch axis.

Therefore, even if an optimum sequence for welding or the like (movement path and movement speed of the machining point, laying angle of the torch with respect to the work surface, change over time of twist angle, etc.) is given, the P point or the matching P point can be given. It is extremely difficult to teach the contents of changes in the position / orientation with respect to point P over time. In particular, regarding the moving speed v of the processing point, it is difficult to realize it with high accuracy even with the most basic control of keeping this constant. To forcefully realize accurate control, the number of teaching points must be increased, which requires many complicated calculations, resulting in a significant decrease in work efficiency.

Such a problem is not limited to the above-mentioned arc welding work, but is performed when a work of a type in which a robot or the like handles an object such as a work while being associated with a particular position or a particular region in the work space. It is a property that occurs in common.

The problems to be solved by the present invention occur in common when an object such as a work is handled by a robot to perform a work while being associated with a specific position or a specific region in a work space. Is to overcome the problem.

[0022]

According to the present invention, when controlling a robot for handling an object carried by a robot in association with a specific position or a specific region in a work space, the specific position or the specific region is controlled. One or a plurality of specific points representing a specific area are set as tool tip points, and time-dependent change data of the tool tip points with respect to a specific portion of the robot having a fixed relationship with the carried object is obtained. The above problem is solved by teaching the robot and controlling the robot.

Further, according to the present invention, the above requirements are satisfied in the case where the specific position or the specific area in the work space corresponds to the arrangement position or the arrangement area of the means placed in the work space. A control method for a robot that performs control is provided.

[0024]

The feature of the robot control method of the present invention is that, in the example of FIG. 1, the representative points P on the workpiece are not set as the tool tip points, but the representative points T1 to T3 of the torch T are set as the tool tip points. The point is to set and control the robot. Therefore, the principle of achieving desired handling by such a tool tip point setting method will be described with reference to FIG.

FIG. 3 conceptually shows the mutual relationships among the representative points T1, T2, T3, the base coordinate system ΣB (origin O), the hand coordinate system ΣH (origin H), etc. in the arrangement shown in FIG. It is shown in an enlarged scale.

Since the points T1, T2 and T3 are fixed points on the base coordinate system ΣB, the position vectors <T1> B, <T2> B and <T3> B originating from the origin O are constant vectors. . The XYZ components are (X1, Y1, Z1) (X
2, Y2, Z2) (X3, Y3, Z3). These values represent a point representing the torch T fixedly arranged at a specific position or area in the work space on the base coordinate system set as a fixed coordinate system in the same work space. , Here are all constants.

On the other hand, the position vectors <T1> H, <T2> H, <T3> H starting from the final wrist point H are vectors that change with the progress of the welding process. Each component represented on the hand coordinate system ΣH is (x1, y1, z1)
(X2, y2, z2) (x3, y3, z3). These values change every moment in response to changes in the processing position or the processing posture (workpiece direction).

Hand coordinate system Σ seen on the base coordinate system ΣB
The position of the origin of H is the position vector <OH> = (XH, YH
, ZH), and the posture of the hand coordinate system ΣH seen on the base coordinate system ΣB can be represented by a coordinate rotation matrix [R] BH of 3 rows and 3 columns representing coordinate rotation. With this relationship,
The coordinate value (Xk, on ΣB) of each representative point Tk [k = 1,2,3]
The relationship between Yk, Zk) and the coordinate values (xk, yk, zk) on ΣH is expressed by the following equations (1) to (3). Further, by taking the difference between the equations, equations (4) to (6) are obtained.

[0029]

[Equation 1]

[0030]

[Equation 2] Here, as described above, each constant vector <T1> B, <
XYZ components of T2> B and <T3> B, (X1, Y1,
Z1), (X2, Y2, Z2), (X3, Y3, Z3)
Is a constant, and the number of components of the coordinate rotation matrix [R] BH is 3 × 3 = 9. Therefore, all the representative points T1, T
2, given the component data on the hand coordinate system ΣH of T3, the equations (4) to (6) can be combined to solve the equation in which the nine components of the coordinate rotation matrix [R] BH are unknowns. I can. Specifically, for example, the difference of each component in each coordinate system is calculated as follows: Δ (X) ij = Xi-Xj, δ (X) ij = xi-
xj, ... .DELTA. (Z) ij = Zi-Zj, .delta. (Z) ij = zi
-Zj, etc., define the matrices [Δ] B and [δ] H represented by equations (7) and (8), and the equation; [Δ] B =
[R] BH ・ [δ] H ・ ・ ・ Solve (9), then [R]
By calculating BH = [Δ] B · inv. [Δ] H (10), all nine components of the matrix [R] BH can be determined. Here, inv. [A] represents the inverse matrix of the matrix A.

[0031]

[Equation 3] If all the elements of the matrix [R] BH are determined, equation (1),
The vector <O based on either one of (2) and (3)
Each component of H>, that is, the coordinate value of the final wrist point M on the base coordinate system ΣB can be determined.

As can be seen from the above description, if the values of both the base coordinate system and the hand coordinate system are determined as the data representing the position / orientation of the torch T, the base of the hand coordinate system ΣH with the final wrist point M as the origin. The position and orientation seen on the coordinate system ΣB are completely determined.

Therefore, the three representative points T1 and T of the torch T are
2, T3 is set as the tool tip point, and the above-described calculation method is stored in the robot controller in advance.
Position data of these representative points on the hand coordinate system ΣH (x
If we teach k, yk, zk) [k = 1,2,3], point T1,
Robot control can be realized with T2 and T3 set as the tool tip points.

The method of teaching the position data (xk, yk, zk) [k = 1,2,3] of the representative point on the hand coordinate system ΣH including the change over time (movement velocity) is the conventional method. P in FIG.
It is a much more rational method than teaching point change data over time. This is because, in view of the nature of the work of handling the position or area where the torch T is present, it is common to set the representative point (T1, etc.) at a position where the relationship with the machining point is clear. On the other hand, it is easy for the work W itself to specify or grasp on the hand coordinate system the position of the processing point (welding position), the relative attitude of the torch with respect to the work, or their temporal changes (speed). Because it is fixed on the system ΣH, it is customary to do it reasonably if the work content is clear.

In the above example, as long as arc welding is performed, the loci and movement speeds of the welding points to be drawn on the work W, and the data of the relative attitude with respect to the torch corresponding to each welding point or the welding time point are used for the welding operation. It should always be given as basic data, and it is generally not difficult to convert it into data on the hand coordinate system ΣH in which the work W is fixed. Further, if the method of designating the basic data specifying the welding work contents from the beginning by the hand coordinate system data regarding the representative points T1 to T3 is adopted, the conversion work can be omitted.

If, in the form of data on the hand coordinate system ΣH, information about the locus and movement speed of the welding point to be drawn on the workpiece W, and information on the relative posture with respect to the torch T corresponding to each welding point or welding time point is given, Immediately after making a minute correction in consideration of the gap ε between the processing point Q and T1, T1, T2,
The data represented on the hand coordinate system ΣH of T3 can be obtained.

In the case where the gap ε is not required to change with time, ε = 0, that is, T1 is set so as to match the machining point Q, so that the above correction becomes unnecessary. When the gap ε needs to change over time, it is reasonable to set ε = ε (t), match the processing point Q at the start of welding (t = 0) with T1, and set ε (0) = 0. Target. Gap ε
Is generally defined as a vector quantity. (A more detailed specific example of the correspondence between the work content and the representative point data teaching will be described in the Example section.) Here, a particularly important fact is that the point P in FIG. 1 is designated as the tool tip point. Unlike the above method, according to the control method of the present invention in which the representative points T1 to T3 are taught as tool tip points, the representative point (T1) which can be brought close to or coincide with the machining point is represented on the hand coordinate system ΣH. This means that the time-dependent change substantially coincides with the time-dependent change (moving speed) on the workpiece at the processing point Q. Further, it is also one of the salient features of the present invention that the temporal change in the posture (angular velocity of the posture change) substantially coincides with the posture change of the remaining representative points (T2, T3) in the hand coordinate system ΣH. Is.

In other words, by the tool tip point setting method adopted in the control method of the present invention, data directly connected to the actual image of the work content (in particular, the moving speed of the processing point or the angular velocity of the attitude change) is designated. Since the teaching work of the robot can be performed in the form described above, the robot control that realizes the motion that exactly matches the intended work content can be performed without complicated work.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As one specific example of the work to which the robot control method of the present invention is applied, the present invention is assumed by assuming the case shown in FIG. 4 in which the arrangement shown in FIG. 1 is extracted and enlarged. An example will be described. First, how to give data when the representative points T1, T2 and T3 are set as tool tip points will be described.

The work W, of which only a part is shown in FIG. 4, is a hand coordinate system ΣH as a cylindrical object to be welded with a radius d.
It is supported parallel to the x-axis of the. Axis J is point J0
It intersects with the y-axis at (0, Jy, 0). Although the outline of the torch T itself is not shown, a triangle Γ on the plane defined by the points T1, T2, and T3 representing the region where the torch T exists.
(T) is displayed as a spot pattern. This surface Γ (T) is a fixed triangle on the base coordinate system ΣB (not shown),
It is not fixed on the hand coordinate system ΣH.

FIG. 4 shows a state where welding is started from the point Q0 by the torch. Starting from this state,
It is assumed that the work is completed by drawing the welding line I so as to sequentially pass through Q1, Q2, Q3 ... Qn, Qn + 1 ... And finally return to Q0. Welding start point Q0
Is located at the intersection with the surface of the work W when a straight line parallel to the z-axis is established from the point where the x coordinate on the axis J is α0. The coordinate value of the point Q0 is (α0, Jy, d). Hereinafter, generally, the coordinates of the point Qn are represented by (αn, βn, γn). This value indicates that the workpiece W is in the hand coordinate system ΣH.
Since it is fixed above, it does not change at all as the welding process proceeds.

A representative point serving as the first tool tip point near the tip of the torch T is set as T1, and this T1 is set so as to coincide with the welding point Q0 at the start of welding. Then, of course, T
The initial coordinate value of 1 is T10 = (α0, Jy, d).
On the other hand, as the initial value of the attitude of the torch T with respect to the work W, the initial coordinate values of T2 and T3 corresponding to the torch attitude to be realized at the start of welding T20 = (x20, y20, z2
0) and T30 (x30, y30, z30) are set as the data of the second and third tool tip points.

Here, it should be noted that
This means that the three tool tip points T1 to T3 cannot be designated completely independently. That is, a constraint condition is imposed on the three points to form one constant triangle Γ (T) shown by a speckled pattern.

Therefore, when designating the concrete data of the tool tip points T2 and T3, T2 must be observed while complying with the above conditions.
, T3 are taught directly on the hand coordinate system ΣH, or the data is taught in such a manner that the above-mentioned constraint condition is automatically satisfied by devising the setting position of T2 and T3 and the method of designating the coordinate data. Either method is adopted.

Explaining one of the devised methods,
First, the direction cosines (ex, ey, and y) of the vector <T1 T2>
ez) on ΣH, and the length D (= T1 T of the vector)
2 distance) is used to determine the value of T2. And T3
For, consider a sphere Λ with a radius D centered at T1 as shown, set T3 on the arc corresponding to the equator when T1 is the center of sphere Λ, and T2 is one pole, and the vector The coordinate value of T3 is fixed by designating one component of the direction cosine f = (fx, fy, fz) of <T1 T3>, for example, the x component (fx), and teaching is performed.

That is, the vectors <T1 T2> and <T1 T3
> Have lengths D and are orthogonal to each other.
Since the two independent conditional expressions (9) and (10) represented by (10) are satisfied, if three components of e have already been designated, only one component of f needs to be designated. The remaining two components are unconditionally determined.

[0047]

[Equation 4] Here, the above-mentioned one component is the y component fy, and its initial value is f
The point T3 is set on the spherical surface R so that y0 = 0. After all, the initial values of T1 to T3 are expressed by the following equations (11) to (1
It becomes like 3). The specific numerical values of the x and z components of f are based on the numerical values of the x and z components of e based on the equation (1
4) and (15) may be solved and set.

[0048]

[Equation 5] Next, an example of how to specify the tool tip point data corresponding to the nth point Qn on the welding line after Q0 = T10 will be described. As the welding process progresses, the nth point Qn becomes Q0 in FIG.
Assuming that the point has been reached, if the gap ε between the point T1 and the welding point Qn remains 0, the coordinate of Qn becomes T1n. However, since ε is not always 0, it is necessary to correct the value of Qn by εn. As described above, εn is a vector quantity.

Once T1n is determined, three components of the direction cosine of the vector <T1nT2n> en = (exn, eyn, ezn) and the y component of the direction cosine f of the vector <T1nT3n> are determined in the same manner as in the case of T20 and T30. The data of the three tool tip points T1n, T2n, T3n may be determined and taught through designation of fyn. The equations that define T1n, T2n, and T3n are (16)-
It becomes like (20).

[0050]

[Equation 6] The outline of the teaching procedure of the position data of the tool tip points T1 to T3 is as described above, but in order to properly execute the welding work, the movement speed of the welding point with respect to the torch is controlled as close as possible to the desired value. That is also extremely important. According to the method of the present invention, since the tool tip point T1 can be set at a position close to the welding point, the hand coordinate system ΣH
It can be considered that the moving speed of T1 above is substantially equal to the moving speed of the welding point on the work W.

Therefore, as the velocity of the tool tip point T1,
It is only necessary to teach the moving speed of the welding point to be realized. (It is needless to say that a correction may be made in order to perform more strict speed control.) Specifically, each teaching point Ti-1 Ti (i
= 1,2, .. N), the speed v i should be taught sequentially as being equal to the welding speed to be realized. At that time, for example, there is almost no movement (change) in T1, and the torch T
For a section in which the relative posture of the workpiece W is significantly changed, a sufficiently small velocity v is taught to avoid a sudden posture change of the workpiece W and prevent excessive load on the robot wrist. You can take action.

Next, a robot controller used for executing the teaching according to the above-described method and controlling the robot based on the teaching will be described with reference to FIG. 5, which is a block diagram showing a main part thereof.

In FIG. 5, a robot controller 10 represented by reference numeral 10 has a central processing unit 11 (hereinafter referred to as a CPU), and the CPU 11 has a memory 12 including a ROM in which a control program is stored, A memory 13 including a RAM for storing various set values, teaching data, etc., teaching data for teaching the robot to operate, various commands, calculation programs, etc. are input, and the contents stored in the memories 12, 13 are output or A robot axis control unit 15 for controlling each axis of the robot main body R via a teaching operation panel 14 having an input / output / display function such as displaying, and a servo circuit 16.
Are respectively connected via the bus 17.

Although the above-mentioned configuration is basically the same as that of the conventional robot controller, when this robot controller is used to carry out the robot control method of the present invention, it is inputted from the teaching operation panel 4. Calculate the coordinate value data of T2 and T3 based on the coordinate value data of the tool tip point T1 and the direction cosine data ex, ey, ez, fy (or fx, fz) of T2 and T3 and the distance D between T1 and T2. Equations (14), (15), (1
9) to (22) and the like, and a calculation program for executing the calculation for solving the equations corresponding to the formulas (10) and (1) based on the calculation result are RAM.
13 or ROM 12 is different from the conventional one in that it is stored in advance.

1 to 4, the robot controller is used to teach the robot in accordance with the above-described method, and the robot is controlled based on the taught program. An example will be described with reference to the flowcharts shown in FIGS. 6 and 7.

First, the teaching procedure will be described. The power of the robot controller 10 is turned on, the program screen is called to start the teaching operation (teaching start), and the teaching point index j is reset to j = 0 (step S1). . Next, when fixed point data <T1> B <T2> B <T3> B on the base coordinate system ΣB representing the position or existence area of the torch T is input from the operation teaching board 14 and stored in the RAM 3 (step S2), Immediately according to a command from the CPU 1, D = T
The distance between 1 T 2 = the distance between T 1 and T 3 is calculated, and the data of the calculation result is also stored in the RAM 3 (step S
3). How to select the setting positions of T1 to T3 is as described above (see FIG. 4).

As a starting point of data teaching regarding the tool tip point, first, the coordinate value T10 on the hand coordinate system ΣH of T1 is taught. Since T10 is set to coincide with the welding start point Q here, T10 = (α0, Jy, d)
Is input from the teaching operation panel 14 (step S4).

Next, data of T2 and T3 are taught as tool tip point data corresponding to the attitude of the torch T. Since the method of designating the direction cosine described above is adopted here, the direction cosine data of T2 (ex0, ey0, ez0)
Is input first (step S5).

For the initial value T20 of T2, the above equation (1)
The calculation corresponding to 4) is executed by the instruction of the CPU 11, and the RAM 1 is in the form of coordinate value data on the hand coordinate system ΣH.
3 (step S6). When the input of the data of T2 is completed, one component of the direction cosine f, here the value of fy0 is designated and input as the data of T3. This data may be considered as posture data regarding the twist of the torch T. The CPU 1 immediately substitutes the value of fy designated in the equations (16) and (17) to determine fz = fz0, and based on that, executes the calculation corresponding to the equation (15) to execute the hand coordinate system of T3. The coordinate value on ΣH is confirmed and stored in the RAM 13 (step S8).

The tool tip points T1, T2, T3
Since the teaching of the position data at the start of welding is finished, the process proceeds to step S9, and the moving speed v = v0 of the robot between the teaching points is taught. The first speed teaching is performed by instructing a proper value as the moving speed in the route (not shown) from the standby position (home position) of the robot carrying the work W to the welding start position shown in FIG. Just enter it. The robot's moving speed is taught in various forms, such as specifying the speed value (eg, mm / sec) itself, specifying the ratio (%) to the maximum speed, or specifying the required travel time (sec). Not to mention getting it.

At step S10, the teaching contents of the tool tip point data corresponding to the welding start point are confirmed by using the display function of the teaching operation panel 14 or the like, and 1 is added to the teaching point index j (step S11). Returning to step S4, teaching of position data T11, T21, T31 of the next teaching point is started.

First, considering the gap ε = ε1 between T1 and the welding point Q1 to be realized, n in the equation (18) is satisfied.
= 1 is input (step S4). here,
The data of α1, β1, γ1 and the x, y of the gap ε1,
The data of each z component should be given as the data of the welding work content. Next, the three components of the direction cosine e are input as the data of T2 corresponding to the welding point Q1 (step S5), the equation (19) is calculated under the condition of n = 1, and T21 on the hand coordinate system ΣB is calculated. The value is stored in the RAM 13 (step S6).

Then, as in the case of j = 0, the y component fy1 of the direction cosine is designated for T3 (step S3).
7), equations (21) and (22) are combined to solve the simultaneous equations, and the data on the hand coordinate system of T31 is stored in the RAM 13 (step S8). The speed specified in the next step S9 is realized when the robot carrying the work W actually moves and the welding point Q1 moves from the position shown in FIG. 4 to the position shown by Q0. Speed v1
Should be specified. Since this speed can be regarded as being substantially the same as that grasped as the relative speed of the welding point with respect to the torch T fixed in the work space, it was intended to be realized at the time of teaching when executing the teaching program. There is almost no fear that the actual welding operation will be performed at a speed far from the welding speed value. This feature is
The same applies to the velocities v2, v3, ... VN in the other sections.

Now, again, confirm the teaching contents in step S9,
After the steps of adding the teaching point index in step S10 and checking the unset teaching point in step S12,
Returning to step 4, T1, T2, T3 corresponding to the next welding point Q2
The teaching work of is repeated.

In the example shown in FIG. 4, since the welding line I makes one round and returns to Q0 and QN = Q0, step S
By repeating the cycle from 4 to step S12 a total of N + 1 times, a YES determination is made in step S12. Finally, the program name, program code number K, etc. are registered (step S13), and the teaching operation is completed.

With respect to the robot for which the data input of the above teaching program is completed, the program is reproduced and executed,
An example of the process of the CPU 11 when controlling the robot will be described below with reference to the flowchart shown in FIG.
At the time of starting the operation, the robot is in the standby state at the home position.

The operator operates the teaching operation panel 4 to select the program reproduction mode to start the robot control operation (start). First, when the program code number K is designated, the taught program is called (step M1), and the teaching point index j is reset to j = 0 (step M2).

Then, one block of the program is read (step M3), and the RAM 13, T10, T20, T is read.
Each data of 30 is read out, and according to the calculation procedure described in the section of the description of the action [in particular, see the formula (10)],
j = 0, that is, a matrix RBH-j representing the posture of the hand coordinate system ΣH on the base coordinate system ΣB at the start of welding is calculated (step M4). Then, based on the result [see especially equation (1)], the hand coordinate system Σ corresponding to j = 0
The coordinate value (XH, YH, ZH) j = 0 of the origin of H (final wrist point H) on the base coordinate system ΣB is calculated (step M5).

Interpolation calculation is performed to move to the teaching point corresponding to j = 0 (step M6), and based on the result, the movement to [XH, YH, ZH; RBH] j = 0 is executed. (Step M7). In the first cycle, the section [j-1, j] is assumed to be between the robot's current position (home position) and the teaching point corresponding to j = 0. Therefore, the data required for the interpolation calculation can be obtained from the current position data of the robot. If the movement is of a nature that does not require interpolation calculation such as simple straight line translation, it is possible to proceed directly to step M7 without performing interpolation calculation and move to [T10, T20, T30].

When the movement is completed, 1 is added to the teaching point index (step M8) and it is judged whether or not the final target point is reached (step M9). If j is not N + 1, it means that it has not been reached. Therefore, the process returns to step M3 to read the next one block of the program, and for j = 1, the processes of steps M3 to M9 are performed. Similarly, for j = 1, 2, 3, ...
3 to step M9 are repeated to return to the state shown in FIG. 4, which is the final target point, and the program reproduction execution operation is ended (END).

The above embodiment is an example in which the robot control method of the present invention is applied to handling type arc welding, but the scope of application of the present invention is not limited to the arc welding work as in this embodiment. It can be applied to all types of work for handling an article in association with a specific position or a specific area. For example, mechanical processing means fixedly arranged in the work space, coating means, marking means, light irradiation means (its light irradiation area), radiation irradiation means (its irradiation area), heating means, photographing means (camera field of view). ) Etc. can be considered as handling for accessing a specific part of the work.

If the degree of freedom of movement required in accordance with the nature of the work is small, two or only one tool tip point is set instead of setting three tool tip points. It is possible to teach. In the example described above, if the degree of freedom corresponding to the twist of the torch T is not required, the setting of T3 is essentially unnecessary. In addition, if the posture of the torch T does not matter, the robot can be controlled by setting only T1.
However, even in such a case, after setting T1, T2 and T3, the direction cosines ex, ey and ez at the time of data teaching.
Alternatively, it goes without saying that a fixed value can be designated as the data of fy (or fx, fz).

[0073]

According to the present invention, in a work of a type for handling an object carried by a robot in association with a specific position or a specific area where the processing means or various processing means in the work space is present, One or more specific points representing a specific position or the specific area is set as a tool tip point, and the tool tip point of a specific portion of the robot having a fixed relationship with the carried object is set. By teaching position change data over time to the robot, handling with a very high degree of coincidence with desired contents can be realized.

The change over time represented on the hand coordinate system ΣH of the tool tip point that can be brought close to or coincide with the specific position or area is the change over time (moving speed) of the target point such as machining or processing on the object. Since they substantially coincide with each other, it is possible to perform the teaching work of the robot by designating the data directly connected to the actual image, particularly regarding the moving speed of the processing point and the angular velocity of the posture change. Therefore, when the program is reproduced and the robot is actually operated, it is extremely unlikely that a trajectory or moving speed different from what was intended at the time of teaching is displayed.

The present invention is a handling method, and processing (welding) in a specific one or region by mechanical processing means, coating means, marking means, light irradiation means, radiation irradiation means, heating means, photographing means (field of view of camera), etc. Cutting, gluing,
It can be widely applied to work such as perforation) or treatment (painting, marking, light irradiation, radiation irradiation, imaging, etc.), and the above outstanding features are surely exhibited when applied to any application. Therefore, it is extremely useful in improving the accuracy and efficiency of these operations.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of an arrangement when a robot control method of the present invention is applied to a handling type arc welding work.

FIG. 2 is a conceptual diagram for explaining the problems of the conventional technology.

FIG. 3 is a conceptual diagram for explaining the principle of realizing desired handling based on the tool tip point setting method used in the robot control method of the present invention.

FIG. 4 is a diagram showing a part of the arrangement drawn in FIG. 1 in an enlarged manner in order to explain an embodiment in which the robot control method of the present invention is applied to a handling type arc welding work.

FIG. 5 is a principal block diagram showing a robot controller used when implementing the control method of the present invention.

6 is a flowchart showing a teaching process in an embodiment in which the present invention is applied to the handling type arc welding operation shown in FIG.

7 is a flow chart showing a process when the program taught according to the flow chart of FIG. 6 is reproduced to execute the arc welding work of the handling system shown in FIG.

[Explanation of symbols]

W, W'Workpiece J, J'Workpiece W, W'axis d Workpiece W radius R Robot I Welding line Q Welding point Q0 Welding start point T Torch T1, T2, T3 Tool tip point (torch existence area representative point) Γ (T) Constant triangle H Final wrist point (hand coordinate system ΣH origin) G Arm P, P ′ Fixed point on work W O Origin of base coordinate system ΣB Sphere 1, 2 Pair 10 Robot controller 11 Central processing unit (CPU) ) 12 memory (ROM) 13 memory (RAM) 14 teaching operation panel 15 robot axis control unit 16 servo circuit

Claims (2)

[Claims] 1. A robot control method for handling an object carried by a robot in association with a specific position or a specific area in a work space, wherein one or a representative of the specific position or the specific area is provided. A plurality of specific points are set as tool tip points, and position change data over time of the tool tip points with respect to a specific portion of the robot having a fixed relationship with the carried object is taught to the robot. A method for controlling the robot, which is characterized in that 2. The robot control method according to claim 1, wherein a processing means for the object carried by the robot is arranged at a specific position or a specific region in the work space.