JPS6346844B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an articulation teaching device for an articulated robot. Normally, when teaching the motion of a playback robot, it is necessary to actually move the robot and memorize the position in the robot.However, conventionally, there were two forward/reverse instruction switches on the console for each axis of the robot's movement, and one axis I moved it every time, adjusted its position, and taught it indirectly. Therefore, when positioning the robot at a required point, it was necessary to use switches on all axes separately to move the robot, which required skill and a great deal of time to adjust the position.
In addition, restrictions may occur on the robot's movement trajectory due to obstacles or when inserting a workpiece into a hole during assembly, and if the movement of each axis is inconsistent, it may not be possible to teach the robot in a state similar to the actual work. This caused an inconvenience in the teaching work. The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to improve the functionality and simplify the indirect operation when teaching the motion of a playback robot, and to improve the teaching operation and shorten the working time required for teaching. An object of the present invention is to provide an indirect teaching device for an articulated robot. That is, in order to achieve the above object, the present invention provides an articulated robot having at least three degrees of freedom, which includes a drive means for driving each joint, and a position detection means for detecting the amount of rotation of each joint, and has at least three degrees of freedom. an angle/orthogonal transformation matrix means for converting the angular displacement amount of each joint detected by the means into position coordinates of an internal reference orthogonal coordinate system for each sample; and an origin change or hand posture movement for instructing an origin change or hand posture movement. Drive the instruction switch and the driving means to move the joint, position it at the reference position of any teaching Cartesian coordinate system, and operate the origin change or hand posture movement instruction switch to move the joint when it is positioned as described above. orthogonal coordinates for teaching, in which the amount of displacement of the reference orthogonal coordinate system from the reference position is detected by the position detecting means or the angle/orthogonal transformation matrix means, and the value is stored in the storage means to set the orthogonal coordinate system for teaching; system setting means, an axial direction instruction switch for instructing each axis direction of the coordinates to move the articulated robot, and unit vector generation means for sequentially generating a unit movement amount for each sample by operating the axial direction instruction switch; The amount of displacement from the reference position stored in the storage means of the orthogonal coordinate system setting means for teaching is read out, a first transformation matrix is calculated based on this amount of displacement, and this calculated first transformation matrix and the above a first transformation matrix means that sequentially obtains the unit movement amount of the internal reference orthogonal coordinate system by multiplying the unit movement amount sequentially created by the unit vector generation means; Add the position coordinates of the internal reference orthogonal coordinate system at the position and the unit movement amount of the internal reference orthogonal coordinate system obtained by the first transformation matrix means, and multiply this added value by the second transformation matrix. and calculation means for sequentially calculating the rotation angle of each joint to the next target position, and driving the driving means to obtain the rotation angle sequentially calculated by the calculation means to move each joint to the next target position. An articulated robot characterized in that the hand of the articulated robot is positioned at a teaching point by operating the robot, and the position data of each joint is stored in a storage means based on the rotation angle of each joint obtained from the position detection means. It is an indirect teaching device. In particular, an internal reference orthogonal coordinate system is set with the axis of the swivel table installed vertically as the Z axis, and the X and Y axes installed in the horizontal direction orthogonal to this Z axis, and the teaching coordinate system is Shared with the Z axis, set a predetermined angle θ ₁ in the horizontal direction with respect to the above X and Y axes. However, it is characterized by being able to teach straight lines indirectly. Also, set the internal reference orthogonal coordinate system in the same way as above, set the teaching coordinate system with the Z′ axis in the direction the wrist is facing, and set the X″ and Y″ axes perpendicular to the Z″ axis. death,
It is characterized by being able to indirectly teach a straight line along an object placed tilted on a horizontal plane. The present invention will be specifically described below based on embodiments shown in the drawings. FIG. 1 is a diagram showing a schematic configuration of an apparatus for carrying out the indirect teaching method for an articulated robot according to the present invention. 1 is a console used for indirect teaching operations of the playback robot. Here, it is assumed that the industrial robot has six degrees of freedom. Indication switches 2a, 2b, 3a, 3
b, 4a, 4b, 5a, 5b, 6a, 6b, 7
There are a total of 12 a and 7b for indicating forward and reverse directions for X, Y, Z, α, β, and γ. Conventionally, a pair of these forward/reverse instruction switches could only move the corresponding operating axis of the robot. In the present invention, when the axis unit instruction switch 8 is pressed, the above operation is enabled. The difference from the conventional method lies in the provision of an origin change instruction switch 9 and a hand posture movement instruction switch 10. By the way, FIG. 2 shows an example of an articulated robot among industrial robots. That is, 20 is the base, 21
Reference numeral 22 indicates a swivel base which can be rotated at an angle of θ ₁ by a drive motor 16a around the Z-axis perpendicular to the base 20, and 22 is driven around an axis pointing in the X-axis direction with respect to the swivel base 21. θ ₂ by motor 16b
23 is a forearm connected to rotate at an angle of θ 3 by a drive motor 16c around an axis pointing in the X-axis direction with respect to the upper arm 22; 24 is a forearm connected to rotate at an angle of θ ₃ ; The upper half of this forearm 23 is rotated by a drive motor 16d around the axis to θ ₄
The lower half of the forearm is connected to rotate at an angle of
25 is a wrist connected to the tip of the lower forearm 24 so as to rotate at an angle of θ ₅ by a drive motor 16e around an axis pointing in the X-axis direction; 26 is a wrist connected to the tip of this wrist 25; Drive motor 16f around the axis
The fingers are connected so as to rotate at an angle of θ ₅ . The hand 26 is provided with a chuck for grasping parts to be assembled or processed, or a chuck for attaching a tool. Further, 11 is an interface circuit, 12 is a microcomputer, and 13 is an input/output terminal. Further, 14a to 14f are A/D conversion circuits, 15a to 15f are drive circuits that drive each drive motor, 16a to 16f are drive motors that drive each degree of freedom of the articulated robot via a reducer,
17a to 17f are rotary encoders (position detection means) connected to each drive motor 16a to 16f;
18a to 18f are rotary encoders 17a to 1
This is a counter circuit that counts the output pulse train of 7f and extracts the angular coordinate values (θ ₁ to θ ₆ ) of the degrees of freedom (each axis). Therefore, when moving the hand of a multi-axis articulated robot by drawing a trail such as a straight line, the robot's internal reference rectangular coordinate system [X, Y,
Z, α, β, γ] is usually assumed and used. The relationship is shown in FIG. α,
β and γ are angles corresponding to swinging, bending, and twisting of the hand 26. That is, α corresponds to θ ₁ shown in FIG. 2, β corresponds to θ ₂ , θ ₃ , and θ ₅ shown in FIG. 2, and γ corresponds to θ ₄ and θ ₆ shown in FIG. 2. For example, in Figure 2
When moving the robot's hand 26 from _point P ₁ to P ₂ , the angle of each axis P ₁ [θ ₁
~ θ ₆ ] to P ₂ [θ ₁ to θ ₆ ], the hand 26 moves in a random trajectory. This is expressed as the robot internal reference rectangular coordinate system X, Y,
Set Z, P ₁ [X, Y, Z, α, β, γ], P ₂
If the PQ for each sample [X, Y, Z, α, β, γ] is calculated and moved using [X, Y, Z, α, β, γ], the hand 26 can be moved linearly, for example. It becomes possible. PQ represents the robot's current position.
In this case, the orthogonal coordinate system PQ [X, Y, Z, α, β,
γ] and PQ [θ ₁ to _{θ 6} ] drive each axis by calculating the following equation (1) for each sample using a coordinate transformation matrix [TXA]. PQ [θ ₁ ~ _{θ 6} ] = [TXA] PQ [X, Y, Z, α, β, γ]
...(1) The coordinate transformation matrix [TXA] is obtained from the degrees of freedom of each robot, arm length, etc. This method is used when using articulated robots for welding, etc.
This method is widely used as a point-to-point teaching interpolation continuous path drive method. When this method is used for indirect teaching operation, for example, the instruction switches 2a and 2b of the console 1 in FIG.
〜7a, 7b, the unit movement vector M[±
Δx, ±Δy, ±Δz, ±Δα, ±Δβ, ±Δγ],
When the robot is driven by calculating equation (2) for each sample, the robot can move linearly or move the hand 26 on the internal reference rectangular coordinate system X, Y, Z shown in FIG. While holding the position, hand 2
It becomes possible to change the posture of 6. PQ (t) [θ ₁ ~ θ ₆ ] = [TXA] {PQ (t-1) [
X, Y, Z, α, β, γ] PQ (t) [θ ₁ ~ θ ₆ ] = [TXA] {PQ (t-1) [
X, Y, Z, α, β, γ] +M [Δx, Δy, Δz, Δα, Δ
β, Δγ〕} ...(2) By taking the control system one step further and pressing the origin change instruction switch 9, the operator can conveniently change the internal reference orthogonal coordinate system to the Z-axis centered on the Z-axis as shown in Figure 3. It is now possible to change the teaching coordinate system to X', Y', and Z' which are rotated (tilted) by θ1Q. This is properly [internal reference rectangular coordinate system] =
Although it is possible to perform the calculation by setting up the formula of [TM (θ1Q)] [teaching coordinate system], in the present invention, the calculation is performed as follows. First, after operating each axis switch 8, each instruction switch 2a, 2b to 7a, 7b is operated appropriately, and the unit movement amount [Δx, Δy, Δz, Δα, Δβ, Δγ] is calculated by the unit vector generating means 47. The gate circuit 4 generates unit movement amounts sequentially for each sampling.
5 and 46 are turned on and input to the calculation means 48, each drive motor 16a to 16f is driven to rotate the swivel base 21 as shown in FIG. By moving to a position rotated by a displacement θ1Q from the position (Y axis) and operating the origin change instruction switch 9, the displacement θ1Q detected from the rotary encoder (position detection means) 17a and stored in the counter circuit 18a is detected. is stored in the memory (storage means) 41 of the microcomputer 12. As a result, the orthogonal coordinate system for teaching X′, Y′,
This means that Z' (however, Z and Z' are common) has been set. Thereafter, in the orthogonal coordinate system for teaching, by operating the instruction switches 2a, 2b, 3a, and 3b, the unit vector generating means 47 of the microcomputer 12 generates unit movement amounts ±Δx′, ±Δy for each sample based on the sample signal. ' is generated and input to the conversion matrix means 51 through the gate circuit 43. The conversion matrix means 51 reads out the displacement amount θ1Q stored in the memory (storage means) 41 and converts it into a first conversion matrix.

[Formula] is calculated, and the calculation process shown in the following equation (3) is performed using the calculated first transformation matrix and the created unit movement amount, and M (±Δx, ±
Δy) The unit movement amount ^T is sequentially output. At the same time, the memory 49 of the microcomputer 12
Then, the position coordinates PQ (t-1) [X, Y, Z, α, β, γ] of the point PQ (t-1) before sampling are
PQ(t-1) [θ ₁ to θ ₆ ] is inversely transformed by the calculation means 48 and stored in memory. The calculation means 48 further calculates the position coordinates PQ(t-1) [X,
Y, Z, α, β, γ] and conversion matrix means 5
Unit movement amount [Δx, Δy,
Δz, Δα, Δβ, Δγ] and the second transformation matrix [TXA], the rotation angle θ ₁ of each joint is calculated as follows:
The next target position PQt [θ _{1 ~}
θ ₆ ] is sequentially calculated, and based on the sequentially calculated results, the D/A conversion circuits 14a to 14f and the drive circuit 1
Drive motors 16a to 16f via 5a to 15f
is driven. PQt [θ ₁ ~ θ ₆ ] = [TXA] {PQ (t-1) [X, Y,
Z, α, β, γ] + M [Δx, Δy, Δz, Δα, Δβ,
Δγ]} Note that 50 converts [θ1 (t-1) to θ6 (t-1)] output from the counter circuits 81a to 18f to [X(t
-1), Y(t-1), Z(t-1), α(t-1),
β(t-1), γ(t-1)]. As a result, when the conversion matrix means 51 performs the conversion of the above equation (3) for each sample h, and the calculation means 48 performs the calculation, the unit movement vector M of the above equation (3) is calculated as if the operator 31 were to use the console 1 The articulated robot is drawn in the worker's mind by operating the instruction switches 2a, 2b to 7a, 7b in the possible movement directions in the teaching coordinate system X', Y', Z' (Z) of the worker area 32. It can be converted to move in the directions (X' direction, Y direction). The angular coordinate values [θ ₁ , θ ₂ , θ ₃ , θ ₄ , θ ₅ , θ ₆ ] moved in this way and stored in the counter circuits 18a to 18f
]
If this is stored in memory for each sample, the trajectory of the robot's motion will be indirectly taught. By the way, converting only the (Y, Y) axis is (Z,
This is because the α, β, γ) axes do not need to be converted because the directions in which the console buttons move do not change visually even if the work area changes. As a result, the robot can be moved by modifying only the movement vector M without modifying the data of the robot's internal reference coordinate system. Therefore, the second transformation matrix, the coordinate transformation matrix [TXA], is not changed;
Since it can be used under fixed conditions, the program has the advantage of being simple. This is because [TXA] is a huge calculation formula (program). Although the above is a modification of the axis of the swivel base 21, other axes can be changed in the same way. Next, the case where the above algorithm is applied to the hand 26 will be explained. First, the articulated robot is moved in the same manner as in the previous embodiment and positioned at the reference position of the new teaching Cartesian coordinate system X'', Y'', Z''.Then, by operating the hand posture movement instruction switch 10, the rotary Encoder (position detection means)
Detected from 17d to 17f, the counter circuit 18
The displacement amounts θ ₃ to _{θ 6} stored in d to 18f are converted from the reference position of the internal reference orthogonal coordinate system by the conversion matrix means 50 to the teaching orthogonal coordinate system X″, Y″,
Current displacement amount of Z″ to the reference position [αθ, βθ, γθ]
to store the data in the memory (storage means) 42,
The orthogonal coordinate system for teaching X″, Y″, Z″ is set. At the same time, the gate circuit 44 is turned on, and the unit movement amounts Δx″, Δy″, Δz″ generated for each sample by the unit vector generating means 47 are set. is input. The conversion matrix means 52 reads out the displacement amounts [αθ, βθ, γθ] stored in the memory (storage means) 42, calculates a first conversion matrix, and teaches it as shown in the following equation (4). The unit movement amounts Δx″, Δy″, Δz″ generated for each sample by the unit vector generating means 47 in the internal reference orthogonal coordinate system are multiplied by the first transformation matrix to perform movement vector transformation, and Unit movement amount M
Calculate (Δx, Δy, Δz). Then, the calculation means 48 calculates Pt[θ ₁ to _{θ 6} ]=[TXA]
PQ (t-1) [X, Y, Z, α, β, γ] + M
[Δx, Δy, Δz, Δα, Δβ, Δγ]}, and based on the calculation results, the D/A conversion circuit 1
4a to 14f, via drive circuits 15a to 15f,
Drive motors 16a to 16f are driven. Note that the initial X, Y, Z, α, β, and γ are inputted in the memory 49 using X〓, Y〓, Z〓, α〓, β〓, and γ〓,
Thereafter, the calculation means 48 converts θ ₁ to _{θ 6} into X, Y, Z, α, β, and γ, and uses the values. However, PQ (t-1) [X, Y, Z, α, β,
γ] indicates the position coordinate in the internal reference orthogonal coordinate system at the time of the previous sampling. In this way, the articulated robot moves on the (X″, Y″, Z″) axes that are imaged in the posture of the hand 26. This teaching coordinate system (X″, Y″, Z″) is shown in Figure 2. . That is, the axis of the hand 26 is the Z'' axis, and the direction perpendicular to this Z'' axis and perpendicular to the length of the arm member shown in FIG. 3 is the X'' axis.
The axis perpendicular to the Z″ axis and the X″ axis is designated as Y″. This is convenient when teaching the work of inserting a workpiece into a hole. In other words, the postures of the workpiece and hand are usually perpendicular and parallel. This means that the posture of the workpiece can be kept constant and it can be moved along the axes of the workpiece (X'', Y'', Z'' (in this case, the orthogonal coordinate system of the workpiece). For example, when inserting a workpiece into an inclined hole, etc. At this time, align the axis of the workpiece with the axial direction of the hole, and turn the hand posture instruction switch 10.
By pressing , the workpiece can be inserted into the hole by indirect operation during teaching as well as during playback by single-axis switch operation, and the operator can teach the robot by making the actual playback and robot movements the same during teaching. can. The three modes of each axis, the origin coordinate system, and the hand posture coordinate system are distinguished by lamps on the console 1. Further, 53 shown in FIG. 4 is a timer wait provided in the computer 12, and 54 is an operation button provided on the console 1. As explained above, according to the present invention, the following effects are achieved. (1) By allowing the operator to move the robot's fingertips (hands) according to the work area, operations can be made simpler and indirect teaching can be performed more easily. (2) The robot's movement is in the direction of the worker's movement.
Since it matches the coordinate system, it is possible to eliminate operational errors. (3) Even when there are restrictions on the movement trajectory, such as when inserting a workpiece into a hole, the robot can move the workpiece and draw the necessary trajectory through indirect operation, making it easier to perform the actual work. can be taught according to the instructions. (4) The robot can be moved to the target position with a few switch operations. (5) It is expected that (1) to (4) will simplify the operation of the playback robot and reduce the teaching time.
The effect of improving the efficiency of robot operating time can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of an apparatus for implementing the indirect teaching method for an articulated robot of the present invention, and FIG. 2 is a diagram showing the configuration of the articulated robot, an internal reference Cartesian coordinate system,
FIG. 3 is a diagram showing another example of the teaching coordinate system, and FIG. 4 is a configuration diagram showing the teaching apparatus of FIG. 1 in more detail. Explanation of symbols, 8...Each axis switch, 9...Origin change instruction switch, 10...Hand posture movement instruction switch, 12...Microcomputer, 41,
42, 49...Memory, 43, 44, 45, 46
... gate circuit, 51, 52, 56 ... conversion matrix means, 47 ... unit vector generation means,
48... Calculating means, 15a-15f... Drive circuit, 16a-16f... Drive motor.

Claims (1)

[Claims] 1. In a teaching playback type articulated robot having at least three degrees of freedom, which is equipped with a driving means for driving each joint and a position detection means for detecting the amount of rotation of each joint, the position of each joint detected by the detection means is An angle/orthogonal transformation matrix means for converting the amount of angular displacement into position coordinates of an internal reference orthogonal coordinate system for each sample, an origin change or hand posture movement instruction switch for instructing an origin change or hand posture movement, and the driving means. Drive the joint to operate it, position it at the reference position of any teaching Cartesian coordinate system, and operate the origin change or hand posture movement instruction switch to move from the reference position of the internal reference Cartesian coordinate system when it is positioned above. a teaching orthogonal coordinate system setting means for detecting the displacement amount from the position detection means or the angle/orthogonal transformation matrix means and storing the value in a storage means to set a teaching orthogonal coordinate system; and an articulated robot. an axial direction instruction switch for instructing each axis direction of the coordinates in order to move the axis direction in each axis direction of the coordinates; a unit vector generating means for sequentially generating a unit movement amount for each sample by operating the axial direction instruction switch; The amount of displacement from the reference position stored in the storage means of the orthogonal coordinate system setting means is read out, a first transformation matrix is calculated based on this amount of displacement, and the calculated first transformation matrix and the unit vector are combined. a first transformation matrix means that sequentially obtains the unit movement amount of the internal reference orthogonal coordinate system by multiplying the unit movement amount sequentially created by the generation means; and a previous position obtained from the angle/orthogonal transformation matrix means. The position coordinates of the internal reference rectangular coordinate system are added to the unit movement amount of the internal reference rectangular coordinate system obtained by the first transformation matrix means, and this added value is multiplied by the second transformation matrix. 1. An indirect teaching device for an articulated robot, comprising: calculation means for sequentially calculating and determining the rotation angle of each joint to the next target position, and driving the driving means based on the calculation results.