JPH05233065A - Precise positioning device - Google Patents

Abstract

PURPOSE:To easily and accurately execute positioning by measuring the perpendicularity data of the X axis of a robot as discrete data and calculating the corrected value of a position by using the differential coefficient of data subjected to spline correction. CONSTITUTION:In the case of measuring the locus of the top of a parts sucking head 5, the perpendicularity data of an X axis 2 of the robot are measured/ recorded as discrete data by a correction calculating means 17. The correction calculating means 17 calculates the corrected value of the position by using the differential coefficient of data obtained by executing spline correction to these discrete data. When mounting parts, the positions of recognizing points 15 and 16 on a printed board 14 are recognized by a camera 4 for recognition, and robot coordinates at that time are calculated. The correction calculating means 17 calculates the robot coordinates in the case of mounting parts with the recognizing points 15 and 16 as references with the correction based on this coordinate and repeats the correction until error is made less than an allowable value. Thus, positioning to a target point and mounting can be easily and accurately executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a positioning device having a correction calculation means for precise positioning.

[0002]

2. Description of the Related Art In recent years, absolute position accuracy has been required in electronic component assembling apparatuses. 4 and 5 show a positioning robot used in a component assembling apparatus, in which 1 is a robot Y axis, 2 is an X axis, 3 is a bracket attached to a ball screw nut integrated slider 13, 4,
Reference numeral 5 denotes a recognition camera attached to the bracket 3 and a component suction head. The robot Y-axis 1 includes a motor 6, a ball screw 7, a linear guide 8, and a ball screw nut integrated slider 9. The rotation of the motor 6 is transmitted to the ball screw 7,
The rotation is converted into a linear movement by the ball screw / nut integrated slider 9, and the ball screw / nut integrated slider 9 moves along the linear guide 8. In the robot X-axis 2, the rotation of the motor 10 is transmitted to the ball screw 11, and the rotation is converted into a linear motion by the ball screw nut integrated slider 13, and the bracket 10 attached to the ball screw nut integrated slider 13 becomes the linear guide 12. Move along. The recognition camera 4 recognizes the positions of the recognition points P _s 15 and P _e 16 on the printed circuit board 14 of FIG.
7 calculates the positional relationship between the XY coordinates of the robot and the XY coordinates on the printed circuit board, and corrects the position of the robot according to the flow shown in FIG. First, the robot is positioned at the robot coordinates R1 (R1 _x , R1 _y ) and the printed board coordinates P1 (P1 _x , P) of the component suction head 5 at that time are positioned.
1 _y ) is measured with a laser measuring instrument. This measurement is repeated many times to create a correspondence table between the robot coordinates and the printed board coordinates of the component suction head 5, and the correction calculation means 17 stores it. Since this correspondence table is a discrete value, a method of correcting a point in the middle thereof will be described below by taking the X-axis direction as an example. Letting P (P _x , P _y ) be the point at which the component is to be mounted, the _{i that satisfies} R _ix ≤P _x ≤P _{(i + 1) x} is found from the above correspondence table. When the robot coordinate corresponding to P _ix is R _ix and the robot coordinate corresponding to P _{(i + 1) x} is R _{(i + 1) x} , the robot whose R _x obtained by (Equation 1) corresponds to P _x Let's say it's coordinates. The same applies to the Y-axis direction.

[0003]

[Equation 1]

[0004]

However, the above configuration requires an expensive device such as a laser measuring device for measuring the coordinates of the head when creating the correspondence table between the robot coordinates and the coordinates on the printed circuit board. Moreover, the measurement requires a long time. In addition, since the discrete data P _i is proportionally distributed during correction, it is necessary to increase the number of discrete data in order to improve the correction accuracy, which further increases the measurement time.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a precision positioning device that can perform positioning easily and accurately.

[0006]

In order to achieve the above object, the precision positioning apparatus of the present invention uses spline interpolation of discrete data of straightness of a target axis and uses a derivative of the obtained curve. There is provided a correction calculation means for calculating the position of the target point by repeating the interpolation calculation until the position error becomes equal to or less than the allowable value.

[0007]

By the above means, the influence of straightness error caused by the distortion of the shaft center is eliminated.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The external appearance of the hardware configuration of the precision positioning device of the present invention is the same as the conventional one shown in FIGS. 4 and 5, but the function of the correction calculation means 17 is different from the conventional one. FIG. 1 is a flowchart of the position correction calculation performed by the correction calculation means 17 provided in the precision positioning device of the present invention.
The positioning in the X-axis direction is described as an example as in the case of the related art. First, the locus of the tip of the component suction head 5 is measured while moving the robot. The locus should be straight along the X-axis, but in reality it is somewhat curved as in FIG. The correction calculation means 17 records the discrete value of the straightness data and corrects this data by the spline interpolation method as follows. When the robot mounts the parts, the recognition camera 4 moves to the recognition point 1 on the printed circuit board as shown in FIG.
The positions of 5 (P _s ) and the recognition point 16 (P _e ) are recognized, and the robot coordinates at that time are R _s (R _sx , R _sy ) and R _{e, respectively.}
(R _ex , R _ey ). Coordinate P based on the above recognition point
The robot coordinates when the component is mounted on (P _x , P _y ) are obtained by the following procedure. First, a tentative R _x is obtained by (Equation 2).

[0009]

[Equation 2]

When the robot coordinate is R _x , the coordinate P _x ′ of the point where the component is mounted is (Equation 3).

[0011]

[Equation 3]

If the difference between P _x 'and P _x is greater than or equal to the predetermined value ε, R _x is changed to the value of (Equation 4).

[0013]

[Equation 4]

Then, the flow returns to (Equation 3) and P _x ′ is obtained again. This calculation is repeated until the difference between P _x ′ and P _x becomes smaller than the predetermined value ε. When the robot is positioned at the point of the robot coordinate R _x calculated in this way, the component can be mounted at the target point P _x . In this embodiment, spline interpolation was performed to correct the straightness data,
It is also possible to use other interpolation methods.

[0015]

As is clear from the above description, the precision positioning device of the present invention measures the straightness of the positioning device as discrete data by the measurement that can be performed relatively easily, and the correction data of the discrete data is finely divided. By providing the correction calculation unit that repeats the position correction using the coefficient until the error becomes equal to or less than the allowable value, it is possible to easily perform the positioning that guarantees the absolute position accuracy.

[Brief description of drawings]

FIG. 1 is a flowchart of position correction calculation performed by a correction calculation unit included in a precision positioning device of the present invention.

FIG. 2 is a diagram illustrating straightness measurement.

FIG. 3 is a flowchart of conventional positioning calculation.

FIG. 4 is a perspective view of a positioning robot.

FIG. 5: Top view of positioning robot

[Explanation of symbols]

 1 Y-axis 2 X-axis 4 Recognition camera 5 Suction head 15, 16 Recognition point 17 Correction calculation means

Claims (1)

[Claims] 1. A precision positioning device equipped with correction calculation means for measuring straightness data of a positioning device as discrete data and calculating a position correction value using a differential coefficient of the data obtained by correcting the discrete data. ..