JP2743368B2 - Industrial robot control method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the tip of an arm of a general industrial robot, and particularly to a method for performing continuous linear interpolation (hereinafter referred to as linear CP operation). The present invention relates to a passing point control method for an industrial robot when a point is designated as a passing point.

2. Description of the Related Art Conventionally, when performing a straight line CP operation continuously, it is used for a special purpose such as a shortening of a moving time or a coating operation. Therefore, a method of designating a folding point as a passing point is often used. At this time, the following two methods are often used as the passing point control method. The first method is a method of interpolating a trajectory near a break point between two continuous straight line CP operations using a parabola or an arc. The second method is a continuous 2
In two straight line CP operations, a vector in the direction of the turning point that monotonically decreases from just before the turning point so that the speed becomes zero at the turning point, and the speed monotonically increases from zero from the turning point to the next point This is a method of performing interpolation by combining vectors in directions.

Problems to be Solved by the Invention However, in the first method in the conventional method, (1) a large amount of calculation is required to obtain a contact point with a parabola or an arc near a break point of a continuous straight line CP operation, and Poor.

(2) It is not guaranteed against speed change and vibration of the trajectory.

Further, the second method has a number of problems, such as giving a stronger impact to the transmission mechanism when the turning point is an acute angle than when the passing point control is not performed.

The present invention has been made in view of the above problems, and provides a method of realizing a smooth speed / position displacement near a turning point which is an intermediate point of a continuous linear CP operation, and realizing a smooth passing point control. .

Means for Solving the Problems In order to solve the above problems, the present invention provides a process of obtaining a reference vector for bisecting the angle formed by the path of the tip of the robot arm at a folding point from basic vectors before and after the folding point, And a step of obtaining a correction vector based on the data table and the reference vector, correcting the target point, and performing a continuous motion of the robot arm tip path near the turning point.

Further, in the second invention, in addition to the first invention, when the path is corrected near the turning point, the correction start point is variably set.

In the third invention, in addition to the first invention, the correction data table is switched according to the state of the robot arm.

Operation The present invention provides a reference vector that divides the angle formed by the path of the robot arm tip at the break point into two before and after the break point, which is a passing point of the continuous linear CP operation,
By using a predetermined correction data table, the amount of calculation is reduced, and smooth and flexible passing point control is performed.

Embodiment Hereinafter, a passing point control method for an industrial robot according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a principle diagram in an embodiment of the present invention. In the figure, AB and BC are continuous linear CP operations, B is a breakpoint specified by a passing point, ₁ is a command vector per sampling time in AB linear CP operation, and ₂ is a BC straight line
4 shows a command vector per sampling time in a CP operation. If A _o is the correction start point and B _o is the correction end point, A
_n and B _n (n = 1,2, ...) are the straight line CP for each sampling time
It corresponds to the target point of the operation. If not corrected, the next target point A ₃ is B ₄ (A _4), the direction of the vector changes rapidly in the order and makes the position of the B ₄ of B _3, causing vibration. Therefore, in the present invention, the positions of A _n and B _n are corrected with a correction vector, and A _n ′,
The direction of the vector is gradually changed as B _n '. FIG. 2 shows a principle for determining a correction vector, and FIG. 3 shows a flowchart thereof. In step 1, the reference vector as shown in FIG. Is calculated. In step 2, the target point A _n (n = 1,2 ...)
_Is calculated as A _{o An} / A _o B, and a correction constant α is searched in step 3 from a table as shown in Table 1 using the values as parameters.

This gives the correction vector Required by At this time, if the reference vector calculated in step 1 is used, equation (2) can be expressed as follows: = A _{o An} * α * (3)

Since _An is the n-th target point from the start of the correction, it can be replaced by A _{o An} = n * | ₁ |... (4). , = N * | ₁ | α * (5) This was calculated in the step 4, the target point A _n to calculate the corrected A _n 'using in step 5. The same repetition is continued until the correction is completed in steps 6 and 7. As can be seen from equation (5), all numerical values used to derive the correction vector are the normal straight line CP.
It is a known numerical value, such as | ₁ |, ₁ , ₂ , or the like, necessary for performing control, and a correction vector can be obtained without any new numerical value that needs to be derived.

Further, since the correction start point _Ao can be set from the distance of _AoB set on the memory, the setting can be arbitrarily changed.

Also, by having several types of correction data tables, it is possible to correct the passing point portion along an arbitrary route as shown in Table 2 and FIG. The trajectory of the CP control using α and α ′ shown in Table 2 is indicated by a line A and a line B
It is.

As described above, in the present invention, in a continuous straight line CP operation, a reference vector that bisects the angle formed by the path of the robot arm tip at a break point and a correction data table are used in the vicinity of the break point. By correcting the route, it is possible to perform a smooth speed and position change by a simple calculation of a numerical value used for normal linear CP control.

In addition, since the correction start point can be arbitrarily changed, the curvature of the passing point portion can be easily and arbitrarily changed, so that optimum passing point control can be performed depending on the application.

Also, by having several types of correction data tables and switching them arbitrarily, it becomes possible to perform optimal passing point control according to the robot state such as the angle of the folding point B. In particular, in the case of a multi-joint robot, the table can be switched according to the working posture, so that vibration can be suppressed and control can be performed without imposing excessive force on the motor and the transmission mechanism.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a passing point control method of an industrial robot in one embodiment of the present invention, FIG. 2 is an explanatory diagram for determining a correction vector, FIG. 3 is a flowchart thereof, and FIG. FIG. 5 is an explanatory diagram showing a difference in a correction path due to a difference in a correction table.

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tatsuya Kawamura 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-61-157909 (JP, A) JP-A-61- 97708 (JP, A) JP-A-60-193015 (JP, A) JP-A-59-36811 (JP, A) JP-A-58-51305 (JP, A)

Claims (3)

(57) [Claims] 1. A method for controlling an industrial robot by performing a continuous linear interpolation operation using a turning point as a passing point, wherein a reference vector for bisecting an angle formed by a path of a robot arm tip at the turning point is set as a turning point. A step of obtaining a correction vector based on the preceding and following basic vectors and a step of obtaining a correction vector based on the correction data table and the reference vector, correcting the target point, and performing a continuous motion near the folding point on the robot arm tip path. Industrial robot control method. 2. When the route is corrected in the vicinity of a break point, the distance from the correction start point to the break point and the distance are stored, and the correction start point can be arbitrarily set using a storage device that can be arbitrarily rewritten. 2. The method for controlling an industrial robot according to claim 1, wherein the method can be set to: 3. The method according to claim 1, wherein when the correction data table is used, a shape of a path near the turning point is switched by using a determination function of switching between several types of correction data tables according to the state of the robot arm. 2. The method for controlling an industrial robot according to claim 1.