JP3244761B2 - Method of generating interpolation between teaching points of PTP type robot - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for generating interpolation between teaching points of a PTP type robot.

[0002]

2. Description of the Related Art Compensation between teaching points of a conventional PTP type robot.
The method for generating the interval will be described with reference to FIG. Along a certain route
A plurality of teaching points P for the robot arm
₀, P ₁, P_TwoThe teaching method that gives
The arithmetic processing device (not shown) that has₀Teaching from
Point P₁Multiple interpolation points to move at a constant speed v up to
H_{1 (1)}, H_{1 (2)}... H_{1 (n)}, Is obtained in advance, with an arithmetic processing unit
The robot can be stored in the storage
Make it work. Also, the teaching point P₁To P_TwoInterpolation point H up to
_{2 (1)}, H_{2 (2)}... H_{2 (n)}The same applies to.

[0003] That is, the interpolation generating method between the teaching of the conventional PTP robot interpolates the distance from the teaching point P ₀ to the teaching point P ₁ such that the velocity v in accordance with the sampling time, each interpolation point H _{1 (1)} , H _{1 (2)} ... H _{1 (n)} are operated or sampled from the storage unit and operated so as to be at the position, and at the next teaching point P ₁ , the next teaching point P Similarly interpolation points towards the ₂ H _{2 (1),} move with reference to _{H 2 (2) ... H 2} (n). Therefore, interpolation points H _{1 (1)} , H _{1 (2)} ... H _{1 (n)} , H
The distance s between _{2 (1)} , H _{2 (2)} ... H _{2 (n)} is always constant and is expressed by the following equation. s = v × Δt where v is the speed of the robot and Δt is the sampling time.

[0004]

In the above-described conventional interpolation generating method, since the distance between interpolation points is given at equal intervals,
It is possible to operate the arm of the robot at a constant velocity v, but the control problems can occur in the case of turning the robot At a teaching point P _1. In other words, the teaching point P _0, the straight line connecting the teaching points P _1, the teaching point P ₁ linear and varies greatly connecting the teaching points P ₁ and the teaching point P _2, vibration is generated impact to the robot itself Or it may lead to a breakage accident.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and provides an interpolation generating method between teaching points of a PTP type robot capable of decelerating at teaching points for changing directions.

[0006]

According to the structure of the present invention for achieving the above object, the teaching points P _i−1 , P _i , P _{i + 1} are given, and a straight line connecting the teaching points P _i−1 , P _i is formed. teaching point P _i, obtains an angle theta _i at the intersection of a line drawn from P i _{+ 1,} the two interpolation points between the teaching points P _i of the teaching point _{P i + 1 H i (j} ), H i ( This is a method for generating an interpolation between teaching points of a PTP type robot, wherein a distance s _{i (j )} between _{j + 1)} is calculated based on the following equation. _{s i (j) = v i} × Δt × k i (j) However, v _i is the teaching point P from the teaching point P _i of the robot arm
moving speed between _{i + 1,} Delta] t is the sampling time, k i _(j) is the section which moves at a velocity v _i is set to 1, turning
In interpolation around the teaching point to perform, depending on the angle theta _i
Is a correction coefficient represented by the following equation. k _{i (j)} = f (j, θ _i )

[0007]

The interpolation point between the teaching points is determined in accordance with the direction change angle at the teaching point. For example, the distance between the interpolation points near the teaching point where the direction is largely changed is set shorter than when the direction is changed smaller. As a result, the robot in the vicinity of the teaching point where the direction is largely changed decelerates, and therefore, the impact can be reduced.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
This will be described in detail with reference to FIG. FIG. 1 shows an embodiment of the present invention.
You. This embodiment is applied to, for example, a painting robot.
Things. That is, the PTP method for the robot arm
Teaching point P_i-1, P_i, P_{i + 1}When giving ...
The position (not shown) is the teaching point P_i-1, P_iMultiple interpolation between
Point H _{i (1)}, H_{i (2)}... H_{i (m)}By the following procedure
You.

(1) A straight line connecting the teaching point P _i-1 and the teaching point P _i is defined as L _i-1 , a straight line connecting the teaching point P _i and the teaching point P _{i + 1} is defined as L _i , and the straight line L _i- angle θ _i of intersection between the ₁ and the straight line L _i
(deg).

(2) A correction coefficient k _{i (j)} is obtained. In this embodiment, the correction coefficients are k _{i (1)} = θ _i / 180 and k _{i (m)} = θ
_{i +} 1/180, and others were set to k _{i (j)} = 1. That is, the correction coefficient k _{i (j)} of the interpolation point (j ≒ 1, m) which is a section that moves linearly.
Is set to 1 and an interpolation point (j =
1, m), the correction coefficient is k _{i (j)} = θ _i / 180,
θ _{i +} 1/180. In any case, the interval between the interpolation points near the teaching point at which the direction is changed is shorter than the interpolation points which are the other sections that move linearly. Further, the correction coefficient k _{i (j)} is the straight line L when _i-1 and the straight line L _i intersection angle theta _i of is large, and large since the robot hardly turning, straight Conversely L _i-1 and the straight line L _i When the intersection angle θ _i is small, the direction is largely changed, so that it is set small.

(3) Next, the interpolation points H _{i (j)} and H
_i a _{(j + 1)} the distance between s _{i (j)} is calculated based on the following equation. _{s i (j) = v i} × Δt i × k i (j) where, v _i is the teaching point P from the teaching point P _i of the robot arm
The moving speed to _{i + 1} , Δt _i is the sampling time.

The interpolation position H _{i (j)} obtained by the above equation
The robot operates in the following manner. First, the robot moves from the teaching point P _i-1 to the distance s _{i-1 (j)} (= v _i-1 × Δt _i-1 × k _{i-1 (j )} )
, H _{i-1 (1)} , H _{i-1 (2)} ,... H _{i-1 (j)} , H
_{i-1 (j + 1)} ... H _{i-1 (n)} follows. Here, the interpolation point H
_{Since the operation from i-1 (2)} to the interpolation point H _{i-1 (n-1)} can be performed in a straight line, there is no problem even if the operation speed is increased. Therefore, the correction coefficients _{Ki-1 (1)} , _{Ki- 1 (2)} , ... _{Ki-1 (j)} , K
The distance s between the interpolation points, where _{i-1 (j + 1)} and k _{i-1 (n-1)} are set to 1.
Calculate _{i-1 ( j)} .

However, it is necessary to reduce the speed as approaching the teaching point P _i. Therefore, when j = n, the distance s between the interpolation points is calculated using the correction coefficient k _{i-1 (n)} = θ _i / 180.
_{i−1 (n)} (= v _i−1 × Δt _i−1 × ki _{-1 (n)} ) is calculated.
That is, the interval between the interpolation points near the teaching point at which the direction is changed is shorter than that of the interpolation points which are other linearly moving sections. Then, although directed from the teaching point P _i to the next teaching point P _{i + 1,} the interpolation point H _{i (1)} in the vicinity of the teaching point P _i be the using the correction coefficient _{k i (j) = θ i} / 180 Distance s between interpolation points
to calculate the _{i (j) (= v i} × Δt i × k i (j)). This allows the robot to reduce the speed near the bend teaching point.

The robot can move at a constant speed in a straight line with respect to the interpolation point obtained by the interpolation formula, and can operate at a reduced speed near the teaching point where the direction changes. Therefore, the impact at the teaching point where the direction changes can be reduced as compared with the related art. In addition, the bending angle θ _i
In the case where is small, in the past, the direction was changed considerably before the bend teaching point due to the delay of the servo mechanism, but according to the interpolation point method of the present invention, it is possible to decelerate immediately before the teaching point.

In this embodiment, both the acceleration side and the deceleration side are used.
The coefficients were changed, in this case θ_iIs P_{i + 1}Until is confirmed
Because it is not decided by H_{i-1 (n)}There is a disadvantage that is not determined. So
As a countermeasure for_{i-1 (n)}= 1, k_{i (1)}= Θ_i/ 180 and
Then, P_iH at the same time as confirmation _{i-1 (n)}Is determined and k
_{i (1)}The value can reduce the impact.

[0016]

As described above in detail with reference to the embodiment, according to the method of generating interpolation between teaching points of the PTP type robot according to the present invention, the impact is reduced by decelerating near the teaching point where the direction changes. Since the movement can be eased, more accurate movement can be performed as compared with the related art.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an arrangement of interpolation points with respect to teaching points in one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a conventional arrangement of interpolation points with respect to teaching points.

[Explanation of symbols]

_Pi-1 , _Pi , _{Pi + 1} Teaching points _{Hi-1 (1)} , _{Hi-1 (2)} , ... _{Hi-1 (n)} , _{Hi (1)} , _{Hi (2)} ,…
_{Hi (m)} interpolation point

────────────────────────────────────────────────── ─── Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G05B 19/18-19/46 B25J 3/00-3/04 B25J 9/10-9/22 B25J 13 / 00-13/08 B25J 19/02-19/06

Claims (1)

(57) [Claims] 1. A teaching point P _i−1 , P _i , P _{i + 1} is given, and an intersection of a straight line connecting the teaching points P _i−1 , P _i and a straight line connecting the teaching points P _i , P _{i + 1.} obtains the angle theta _i at, two interpolation points H _i between the teaching points P _i of the teaching point _{P i + 1 (j),} H i (j + 1) the distance between s _{i (j)} the formula A method for generating an interpolation between teaching points of a PTP type robot, wherein the interpolation is performed based on the following. _{s i (j) = v i} × Δt × k i (j) However, v _i is the teaching point P from the teaching point P _i of the robot arm
moving speed between _{i + 1,} Delta] t is the sampling time, k i _(j) is the section which moves at a velocity v _i is set to 1, turning
In interpolation around the teaching point to perform, depending on the angle theta _i
Is a correction coefficient represented by the following equation. k _{i (j)} = f (j, θ _i )