JPH0727558A - Calculating method for reducing error in connecting three-dimensionally measured coordinate - Google Patents

Abstract

PURPOSE:To correct the error of the connectively measured three-dimentional measurement result. CONSTITUTION:The connective measuring method utilizing connection points B1, B2 via the first machine point A1 and the second machine point A2 is one of the measuring methods of a three-dimensional measuring apparatus. The angle difference dtheta between a reference line X-X shown by measurement stations P1, P2... before connective measurement and a temporary reference line Xa-Xa shown by measurement stations P5a, P6a after the connective measurement is reflected on the three-dimensional coordinates after the connective measurement for angle correction, thereby the error of the connective measurement is corrected. The connective error contained in the measurement by the second machine point A2 after the connective measurement is corrected, and the measurement precision of the three-dimensional measurement can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a calculation method (algorithm) at the time of joint measurement in the calculation of three-dimensional coordinate values of three-dimensional measurement.

[0002]

2. Description of the Related Art First, a joint measuring method which is one of the measuring methods of a coordinate measuring machine will be described. With a coordinate measuring machine,
The Z direction is always right above the vertical direction, and the joining error before and after the joining is small. Therefore, in order to simplify the description, only the horizontal plane (XY plane) will be described.

Measuring points P1, P2, P3, P shown in FIG.
4, P5, P6 (hereinafter collectively referred to as P)
Coordinate values (x1, y1: x2, y
2: ... x5, y5: x6, y0) will be described as an example. A1 and A2 shown in FIG. 6 are set as three-dimensional measuring machine installation points (hereinafter referred to as machine points). However, the first machine point A1
It is assumed that the coordinate values are accurately measured in advance (or the coordinate value of the machine point A1 is used as a reference). First, the measurement points P1, P2, P3, and P4 are measured from the machine point A1, the coordinate values are determined, and then the coordinate measuring machine is moved to the second machine point A2 for measurement. However, the second machine point A2 is
It is an arbitrary point suitable for measuring the measurement points P5 and P6. In order to obtain the coordinate value of the machine point A2, the machine point A1
After installing the first connecting point B1 and the second connecting point B2 in a place where it can be measured from both A and A2 and measuring from the first machine point A1, move the machine point to A2 and measure the connecting points B1 and B2, By processing the coordinate values of B1 and B2 before moving the machine point and the coordinate values of B1 and B2 after moving the machine point as the same point, the coordinate system of the second machine point A2 is also the same as the coordinate system of the first machine point A1. Then, the measurement points P5 and P6 are measured at the second machine point A2, and the measurement is completed.

This method is called joint measurement, and when the measurement target is a long distance longer than the measurable distance of the measuring machine, or even if it is a short distance, there is an obstacle in the middle of the measurement and all the measurement points are measured from one machine point. Used when it is not possible.

[0005]

Here, the second machine point A2
When measuring the connecting point at, the error occurs and the second connecting point B2
2a is measured, the line connecting B1 and B2 and B
The line connecting 1 and B2a has a small angle dθ (see FIG. 7). At this time, measurement points P5 and P6 from the second machine point A2
Is calculated as P5a and P6a in the coordinate system of Xa-Xa deviated from the coordinate system of the first machine point A1 by a small angle dθ (FIG. 8), different from the actual coordinate value (FIG. 6),
It was supposed to include an error. Further, this error cannot be detected by the coordinate measuring machine, and there is a drawback that the error becomes larger as the measurement distance after connection becomes longer. In view of these points, the present invention has an object to reduce the error in the three-dimensional measurement result of the joint measurement.

[0006]

The calculation method for reducing the error associated with the coordinate linkage of the three-dimensional measurement of the present invention for achieving the above object is one of the measurement methods of the three-dimensional coordinate measuring machine. In, the angle difference between the reference line indicated by the measurement point before the joint measurement and the reference line indicated by the measurement point after the joint measurement,
The gist of the invention is to reduce the error in the joint measurement by reflecting the three-dimensional coordinates after the joint measurement and correcting the angle.

[0007]

[Operation] The reference line of the measurement point measured from one machine point is calculated, and after the joint measurement, the above measurement point is measured again from the other machine point to obtain the reference line. The angle difference between the two reference lines is calculated, this is reflected in the measured value after connection, and the measured value is corrected.

[0008]

[Examples] The present invention makes it possible to eliminate the error at the time of joining by performing the following work at the time of joining measurement of three-dimensional measurement. (1) Two connection points B for data connection after connection measurement
In addition to 1 and B2, two or more points are measured at the already measured measurement point P. (2) The angle difference between the reference line before the joint measurement and the temporary reference line after the joint measurement is detected from the coordinate values of the two measurement points. (3) The measured value after the joint measurement is corrected by correcting the detected angle according to the item 2) above.

Next, the measuring procedure will be described based on the concrete examples shown in FIGS. The actual measurement points are the same as in the previous example.
P1, P2, P3, P4, P5, and P6 are described, and the case where the machine point is moved from the first machine point A1 to the second machine point A2 position as shown in FIG. However, FIG. 1 is a final process diagram (fifth process diagram), and FIGS. 2 to 5 are process diagrams thereof. (1) First, since the coordinate systems are connected in the first step, the measurement points P1, P2, P are changed from the first machine point A1 before the movement as usual.
3 and P4 are measured, and the machine point A1 to the connection point B
1 and B2 are measured (FIG. 2). (2) Next, as a second step, the coordinate measuring machine is moved to the second machine point A2. (3) And from the second machine point A2 to the connection point B as before
Measure 1 and B2, and connect the coordinates. At this time, the second
It is assumed that the connection point B2 has an error and is measured as B2a (FIG. 3). (4) Next, as a third step, two or more points measured in the coordinate system before connection are measured, and also from the second machine point A2 after connection. Here, for the sake of explanation, it is assumed that the measurement points P3 and P4 are remeasured. However, since an error has occurred with respect to the connecting point B2, the coordinate positions of the measurement points after the remeasurement are set to P3a and P4a, respectively. (Fig. 4). (5) Next, as a fourth step, the provisional X-direction reference line Xa-Xa for P3a and P4a is arranged in the same positional relationship as the X-direction reference line XX (hereinafter referred to as standard reference line) for P3 and P4.
(Hereinafter referred to as a temporary reference line) is obtained (FIG. 5). (6) The intersection Q between the standard reference line XX and the temporary reference line Xa-Xa is obtained and used as the corrected origin. (7) Angle d between the standard reference line XX and the temporary reference line Xa-Xa
Find θ. (8) Next, as the fifth step, the measurement points P5 and P6 are measured with the second machine point A2 as a reference. This position is P5a, P
6a (FIG. 1). This measurement result is calculated by using a coordinate value in which the angle is corrected by the angle dθ around the corrected origin as a correction value. That is, the present invention obtains the angle difference dθ, corrects the distance from the second machine point A2 after the connection to the measurement points P5a, P6a, and corrects the coordinate values of the measurement points P5, P6. It is calculated.

[0010]

As described above, according to the present invention, the angle difference between the standard reference line indicated by the measuring point before the joint measurement and the temporary reference line indicated by the measuring point after the joint measurement is obtained to obtain the measured value after the joint. Since the correction is performed, the connection error included in the measurement after the connection is corrected, so that the measurement accuracy of the three-dimensional measurement can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory view of a fifth step according to the method of the present invention.

FIG. 2 is an explanatory diagram of the first step.

FIG. 3 is an explanatory view of the same second step.

FIG. 4 is an explanatory view of the same third step.

FIG. 5 is an explanatory view of the same fourth step.

FIG. 6 is an explanatory diagram of a conventional joint measurement procedure.

FIG. 7 is an explanatory diagram of a measurement error at a connecting point.

FIG. 8 is an explanatory diagram of an error due to a conventional joint measurement.

[Explanation of symbols]

 A1 1st machine point A2 2nd machine point B1 1st connection point B2 2nd connection point P Measurement point XX Standard reference line Xa-Xa Temporary reference line dθ Angle difference

Claims (1)

[Claims] 1. A joint measuring method which is one of the measuring methods of a coordinate measuring machine, wherein an angle difference between a reference line indicated by a measuring point before the joint measuring and a temporary reference line indicated by the measuring point after the joint measuring is calculated by A calculation method for reducing an error associated with coordinate connection in three-dimensional measurement, which is characterized by reducing an error in connection measurement by reflecting the angle on the three-dimensional coordinate after the connection measurement and correcting the angle.