JPH0352003A - Offline teaching device for industrial robots - 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 an offline teaching device for industrial robots,
In particular, the present invention relates to an offline teaching device suitable for use in industrial robots that do not have an acceleration/deceleration control function.

``Conventional technology'' Traditionally, teaching/reproduction type industrial robots have been used as automatic machines that perform tasks such as painting and welding in place of humans, and can flexibly handle a variety of workpieces by changing their operating programs. ing.

In such industrial robots, the operating speed of the robot body is set for each teaching point in a motion program, and the robot body is controlled according to this motion program. Therefore, at the teaching point where the speed changes, infinite acceleration is required from kinematics, and problems such as vibration of the robot body or movement deviating from the predetermined trajectory occur. It was possible.

Furthermore, if the set speed of the operating program changes frequently, this may lead to damage to parts constituting the robot body.

Specifically, for example, when an action as shown in FIG. 8(a) is performed, kinematically it is accompanied by a velocity change as shown in FIG. 8(b). A large acceleration was occurring as shown in C). Note that FIG. 8 shows the displacement in one dimension for the convenience of explanation, and in reality, the displacement has as many dimensions as the degrees of freedom of the robot.

For this reason, conventionally, the above-mentioned problems have been prevented by providing an acceleration control function in the control device of the robot body or by modifying the operation program to one that does not cause large speed changes.

``Problem to be solved by the invention'' However, each of these preventive measures had its own problems. That is, in the former case, since extra processing is performed in the control device, the control device becomes complicated and expensive both in terms of hardware and software. In addition, in the latter case, the operator must modify the motion program based on intuition and experience, which requires time and effort to create the motion program, and it is not possible to reliably limit the acceleration.

The present invention has been made in view of the above-mentioned conventional circumstances, and it is an object of the present invention to provide an offline teaching device for an industrial robot that can easily modify an operation program so that the acceleration of the robot body is limited to a certain value or less. The purpose is

``Means for Solving the Problems'' The offline teaching device for an industrial robot of the present invention is an offline teaching device for an industrial robot that creates a motion program from a plurality of teaching points. The present invention is characterized in that it includes a calculation means having a function of creating a plurality of points from a plurality of teaching points as new teaching points so as to have a predetermined value.

Further, the acceleration value can be arbitrarily set when causing the calculation means to execute the function.

Further, the calculation means performs, for each of a plurality of teaching points, a first calculation that calculates the time required for a speed change as a multiple of the sampling time when the speed change before and after the teaching point is performed at a constant acceleration; A second calculation is performed to calculate the posture change of the robot body at the time of the speed change from the time obtained by the calculation as position data for each sampling time, and the position data obtained by this second calculation is used to calculate the position of the new teaching point. It is characterized in that it performs the process of registering it as data.

"Operation" According to the off-line teaching device for an industrial robot of the present invention, a motion program consisting of teaching points created by the function of the calculation means is such that the speed change before and after the teaching point of the original motion program is The motion program is performed step by step according to the number of generated points along the speed change due to acceleration. Therefore, as the number of points increases, the speed change before and after the point becomes much smaller than the speed change before and after the original teaching point. Therefore, the acceleration generated at the speed change point can be reduced, and by setting the number of points to a sufficient value, the acceleration generated approximately can be made equal to the predetermined acceleration.

``Example'' An example of the present invention will be described below with reference to FIGS. 1 to 7.

FIG. 1 is a diagram showing the configuration of an offline teaching device according to an embodiment of the present invention and a teaching/reproduction type industrial robot to which the device is applied.

In the figure, the symbol l indicates an offline teaching device. This offline teaching device 1 includes a display device 2, a calculation device 3 (calculation means), a floppy disk device 4 for external storage and program data input/output, an input device 5 for system operation, and a printer 6 for information output. It is composed of a figure output block 7.

Here, the arithmetic device 3 obtains position data for a plurality of points in time for changing the velocity before and after the teaching point at a predetermined acceleration according to a flowchart shown in FIG. The present invention has a function of generating operation program data in which the points in FIG.

Further, reference numeral 9 indicates the robot body. The robot body 9 is of a 6-axis articulated type with 3 main axes and 3 axes at the wrist 9a, and is controlled by a control device 8 to move a tool attached to the tip of the wrist 9a to a workpiece 10. The work is done by moving the robot in multiple dimensions. Here, the control device 8 controls the robot body 1 according to an operation program created or modified by the offline teaching device fill and input via the floppy disk 11, and the robot body 1 moves between teaching points at a constant speed. It is controlled so that

According to the industrial robot configured as described above, the robot main body 9 can be operated to perform a desired work based on the operation program created by the offline teaching device 1. If it is desired to limit the acceleration generated in this operation to a predetermined value, the operation program data and the acceleration setting value are input to the calculation device 3, and a new value is generated from these human input values by creating the acceleration limiting program or function. What is necessary is to create operation program data and operate the robot body 9 based on this operation program data.

Hereinafter, the program data generation operation in the acceleration limiting program creation function performed within the arithmetic device 3 will be described in detail. First, the relational expressions that are the basis of the calculations executed in this operation and the symbols used therein will be explained.

The origin of the wrist coordinates of the robot body 9 (coordinates fixed to the wrist part 9a of the robot body 9) as seen from the robot base coordinates (coordinates fixed to the installation surface of the robot body) (base end position of the wrist part 9a) ) is the position vector, and the rotation matrix representing the rotation between the robot base coordinates and the wrist coordinates is, then the relationship between the robot base coordinates and the wrist coordinates representing the posture of the robot body 9, that is, the position data is ? = co. ,o■ e3, 0-, es,e
a], the transformation between this joint angle 0 and the matrix T(R, I) is expressed as R+ x = Trans (e) and e = Invtrans <R* x).

Also, in the two rotation matrices R,, R, Rl
Rot(n.φ")= R r-'-R *= R r
Represented by T-Rt.

Furthermore, for example, if the data of the original motion program consisting of teaching points P1 to P, performs the motion shown by the polygonal line (A) in FIG. An operation can be considered in which the velocity changes around a point are performed at a constant acceleration (hereinafter referred to as "uniform acceleration operation").In this uniform acceleration operation, as shown in Fig. 2, the uniform velocity movement time ?Tv If half of the previous accelerated travel time is τ., and half of the subsequent accelerated travel time is τ6, then T=T, +τ■+τ. (1)
This relationship holds true. In addition, each teaching point shown in Figure 2 (
P-1~pt) x, R, τ. 1, τ. When the data of is given as shown in FIG. 3, the velocity vectors between the teaching points are as follows.

Also, The rotation axis and rotation angle between the rotation matrices are and The rotational angular velocity is It is.

Also, Boyd P. Let t be the time from the time of passing through point P. The matrix R,x representing the posture of the robot body in a constant velocity movement region (2) between and point P, a constant acceleration region (2) before this constant velocity region, and a constant acceleration region (2) after this constant velocity region is as follows.

In addition, let Pt(+) be the output value of the position detection field, which is the raw data regarding the posture of the mouth pot body registered in the original motion program, and the value for the i-th teaching point, and let the joint angle be 0. The transformation between θ=Angle (P t(
i)) P = (i) = DAC (e).

In addition, as a limit value of the acceleration input to the calculation device 3,
The maximum angular acceleration of each axis of the robot is α. ．． ．． (j) [jl
~6] and the maximum acceleration of the wrist portion 1a is aaaX.

Also, the sampling time when the control device 8 controls the robot body 9 is T. shall be.

Then, as shown in FIG. 4, the arithmetic device 3 executes the acceleration limiting program creation function by performing the arithmetic processing of steps sp1 to sp21 below.

[Step SPII: Substitute the initial value "l" to the variable K representing the number of teaching points to be generated, and proceed to STEP SP2.

[Step SP2] 4++ Ha! Ikllr: I. 〃Nino cord early fortune telling 8 wealth,“
1”J,,? Step SP3 to Step S for each teaching point
The process of P20 is repeated, and when the process of teaching point number 1 is completed, the process proceeds to step sp21.

[Step SP3] If the teaching point number i is "l", that is, the first teaching point (
operation start point), perform the following calculations ■ and ■,
Proceed to step SP4.

■Output value P of the position sensor at the starting point of operation. The joint angle of the robot body is calculated from (t) and becomes 0. , e. As well as assigning this 0. The position vector and rotation matrix representing the posture of the robot body are calculated from Ionχ. and R. ，
Substitute into R.

■ Va+ω. ,φ. ＋ fL Or T VO* M
Assign the initial value "O" to each of (2).

[Step SP4] If the teaching point number i is the final teaching point I of the process, the teaching point ■
Calculate the joint angle ^ngle(P-(1)) and substitute it to 0. If not, calculate the joint angle ^ngle(Pt(++1)) of the next teaching point after teaching point i and set it to 0. , is assigned to . Soshippu Fu-S. ．． ．． -/cD
e: + - ; Busy 1? Step sp5: Calculate the position vector and rotation matrix from the joint angle 0, and calculate the I■R. Assign to . Also, Rot(n ., φ
1) = R I-'·R, rL l rφ1 is calculated, and the process proceeds to step SP6.

[Step SP6] The teaching speed v (i) from teaching point i to teaching point ill is 0. If it is greater than jllm+/s, assign v(i) to V, otherwise 0. Assign Ola/s to v1.

Then, the process advances to step SP7.

[Step SP7] Calculate the time required to move between the points represented by the position vector Iwχ (i.e., the wrist position of the robot body 9) at the speed v1, and calculate T. Assign to .

Then, the process advances to step SP8.

[Step SP8] Angle change O*(j)-e of each axis (j = 1 to 6) when the posture of the robot body 9 changes from joint angle 0 to 0.
．． The values obtained by dividing (j) by the maximum angular velocity ωmaxF) of each axis are assigned to T and U), respectively. Then, the process advances to step SP9.

Here, the maximum angular velocity ωmaxF) is a constant set for each robot and input into the calculation means 3 in advance.

[Step SP9] Assign the maximum value in Tel T-(J) to T v,
The velocity vector for moving from the position vector I+ to the point I in this time TVl is calculated and substituted into {circle around (2)}.

Similarly, the angular velocity for rotating by angle ψ1 at time Tv1 and the angular velocity for rotating from joint angle Ol to 0 are calculated and substituted into φ1 and ω1, respectively.

Then, the process advances to step SPIO.

[Step SPIO] Limit value a +max of acceleration at the wrist of the robot
The velocity of the wrist is V. The time required to change from v1 to v1 is calculated and substituted into Taffi. Then proceed to Stenop SPII.

[Step SPII] Limit value α of angular acceleration of each axis. ．． ．． In (j), the angular velocity of each axis is ω. (Calculate the time required to change from D to ω1(j) and substitute it for T.(j). Then, proceed to step S?l2.

[Step SPl2 open T. , T. Half of the maximum value in (J) is calculated and substituted for τ■, and the process proceeds to step sp13.

[Step SP13] τ, which is half of the acceleration time at the teaching point i. , τ■ which is half of the acceleration time at teaching point i-1, and teaching point i
Based on the travel time T''vo from -1 to the teaching point i, the constant velocity travel time from the teaching point i-1 to the teaching point i is calculated using the basic equation (1) described above and substituted into TV. and,
Proceed to step spl4.

Here, τ4. is determined from M■ by the following formula.

τ1,2M■・T. [Step sp14 TV and twice τ6 are respectively set as sampling times T. in the control system of the robot. Divide by , round off to the nearest whole number, and round up to the nearest integer. Then, the calculation results are substituted into M V l r M a t respectively, and the process proceeds to step SP15.

[Step SP15] When M y1 is smaller than "l", "1" is newly assigned to M vl and the process proceeds to step SP16.

[Step SPl6] From the M Vl+ Mat determined in Step SPl4 and Step SPl5, the teaching point il is determined by the following formula.
Calculate the travel time from T to teaching point i. Assign to .

'r(1=T'a (Mv, +0.5 (M.++M
．． t)) Then, at this time T0, the position vector I. Velocity vector and angle ψ for changing from to rI. Calculate the angular velocity for the change by V, respectively. ,φ0
Assign to . Then, the process advances to step SP17.

[Step SP17] If K=l, V. and M y. and V. (K-1
) and S. (K-1) on behalf of each other, step S
Proceed to Pl8.

[Step S P l 8] Ma. The sampling time T. Then, the value obtained by multiplying by 172 is assigned to τ. Then, proceed to step SP19.

? Stenop SP19 acceleration time τ ■Position vector I. Rotation matrix R I + velocity vector V. , v1, rotation axis n. , n. Angle φ. , φ1, the speed change before and after the teaching point i is the set acceleration (a a+aXlα...(j)
) is obtained at each sampling time.

That is, L=O to M. Increase L by one until 1, and perform the following calculations each time in the following order.

t'=T. -L-τ, 1+=(τt-t')"/4 τ,t,-
(τ, + t')”/4τ, r””X++ L IV
o+ttVA! =R 1'ROt[n Or t
+φo]−Rot[n l+ t tφ,]e=inv
trans(I, 7'i')P. (K)=DAC(
e) S. (K)=1V. (K)=V.

D,(k)-Dk(i) K = K −+− 1 ? Then, the process proceeds to step S P20.

[Step sp20] Substitute each value as shown in the following formula and return to step SP3. However, when 1=[, the process proceeds to step sp21.

xI=x*+ f3l=f3tr Rr=Rt* v
o=v++ωO:ωIIMal” Mat, T v
o=TVI+no o=nI+ψ0-ψ1 [Step SP21] Decrease the value of K by "1" and end the process.

Through the above processing from step SPI to step sp21, the velocity change before and after the teaching point (Vo"V++ω
.・The time it takes for ωl) to be performed at a smaller acceleration than the set acceleration (a8, αx(j)) and at a constant acceleration is the sampling time T. It is found as a multiple of MM,
Furthermore, based on this time, the sampling time T. The posture information of the robot body 9 (i.e., the output value P.(K) of the position detector) for each time is calculated, and the intermediate point position data of the new program (the newly generated program for the teaching point of the original program) is calculated. The teaching point of is called the intermediate point.). The number of intermediate points is M for one teaching point of the original program.

The total number becomes +1, and the total number becomes the value of K after completing the -E processing.

Also, the speed data at this intermediate point is S. (K),
V. (K), and the I/O data is D. (K). In addition, S. (K) is the travel time to the next intermediate point at sampling time T. It is expressed as a multiple of .

That is, as shown in FIG. 5, for example, a new intermediate point (indicated by "●" in the figure) is generated for the teaching point (indicated by "○" in the figure) of the original program. It should be noted that FIG. 5 shows the displacement in one dimension for convenience of explanation, and in reality, in this embodiment, the displacement is six-dimensional.

Then, the speed data of the newly created intermediate point is 1(K
)=1 and the sampling time T. This is the value for moving between intermediate points.

Also, in steps SP7 to SP9, the angular velocities of the respective axes are changed to the respective allowable maximum angular velocities ω, . a
In the teaching program so as not to exceed x (J)? A process is being performed to downwardly correct the determined speed V(i) and determine each speed (V,, ω1, φ1) for each axis to move in the same time T,.

Then, when the robot is operated according to the operation program data generated by the above processing, the robot operates so that the trajectory is slightly shifted in time from the original teaching point, as shown in FIG. As shown in (b) of the figure, the speed changes step by step by the number of intermediate points. At this time, the acceleration generated at the intermediate point, which is the point of change in speed, is the speed change ΔV (
v+VO or ω1−ω. > compared to conventional i/M. t
Since it is twice as small, it becomes smaller as shown in FIG. 6(C). That is, the sampling time T. If is set to a sufficiently small value, the robot will move approximately with uniform acceleration motion as shown in FIG. 7, and the generated acceleration will be approximately equal to the set value a. ■Or α■. (j) The following is true.

According to the offline teaching device of this embodiment, the operation program can be changed so that the acceleration generated during the operation of the robot body 9 is approximately equal to or less than a predetermined acceleration.

Therefore, there is an effect that the acceleration of the operation of the robot body 9 can be easily and reliably limited without making any modifications to the robot system consisting of the robot body 9 and the control device 8.

Moreover, since the changed operating program has not changed in any way in its data format, the changed operating program can be modified in the same manner as before.

In addition, since the processing for limiting acceleration can be performed within the offline teaching device, all work related to the motion program, such as teaching work (creating a small program), correction work, and motion simulation, can be performed offline. The effect is that it can be done.

Note that, as mentioned above, according to the operation program created by the offline teaching device l, there is a possibility that the robot body will not pass through the original teaching point;
This can be avoided by teaching twice.

Further, in the above embodiment, the acceleration limit program creation function is provided in the offline teaching device 1, but it may also be provided in the control device 8 of the robot body 9, for example.

[Effects of the Invention] According to the offline teaching device for an industrial robot of the present invention, the operation program can be changed so that the acceleration generated during the operation of the robot body 9 is approximately equal to or less than a predetermined acceleration. Therefore, by controlling the robot using this operation program, it is possible to easily and reliably limit the acceleration of the robot body's motion without making any modifications to the robot system consisting of the robot body, the control device, and the like.

Therefore, it is possible to easily improve the operational accuracy of the robot and extend the life of the parts constituting the robot body.

[Brief explanation of drawings]

1 to 7 are diagrams for explaining an embodiment of the present invention, and FIG. 1 is a perspective view showing the overall configuration of an industrial robot and an offline teaching device. Moreover, FIGS. 2 and 3 are diagrams for explaining basic formulas used in the calculation processing of the calculation device, respectively, and FIG. 2 is a diagram showing the relationship between time and displacement, and FIG. 3 is a diagram showing the relationship between time and displacement. It is a figure which shows the data of each teaching point. Further, FIG. 4 is a PAD diagram showing arithmetic processing of the arithmetic device. In addition, Fig. 5 shows -
FIG. 3 is a diagram for explaining program data generated by the above process, and is a diagram showing the relationship between time and displacement. Also, Figure 6. FIG. 7 is a diagram for explaining the operation of the robot body according to each generated program, and FIGS. 6 and 7 (a) are diagrams showing the relationship between time and displacement, respectively. and (b) of FIG. 7 are diagrams each showing changes in velocity, and (c) of FIGS. 6 and 7 are diagrams each showing changes in acceleration. Further, FIG. 8 is a diagram for explaining the prior art, in which (a) in FIG. 8 is a diagram showing the relationship between time and displacement, and (b) in FIG. 8 is a diagram showing changes in velocity. , FIG. 8(C) is a diagram showing changes in acceleration. 1...offline teaching device, 3...computing device (computing means), 9...
robot body.

Claims (3)

[Claims] (1) An off-line teaching device for industrial robots that creates a motion program from multiple teaching points, and which creates new points from the multiple teaching points so that the acceleration at the multiple teaching points becomes a predetermined value. 1. An offline teaching device for an industrial robot, characterized by comprising a calculation means having a function of creating a teaching point. (2) The off-line teaching device for an industrial robot according to claim 1, wherein the value of the acceleration can be arbitrarily set when causing the calculation means to execute the function. (3) The calculation means performs a first calculation for each of a plurality of teaching points, which calculates the time required for a speed change as a multiple of the sampling time when the speed change before and after the teaching point is performed at a constant acceleration; A second calculation is performed to calculate the posture change of the robot body at the time of the speed change from the time obtained by the calculation as position data for each sampling time, and the position data obtained by this second calculation is used to calculate the position data of the new teaching point. 2. The offline teaching device for an industrial robot according to claim 1, wherein the offline teaching device for an industrial robot performs a process of registering the information as position data.