JPH0810129B2 - Automatic measurement method of posture and dimension of target object - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to assembly of parts in automobiles and home appliances,
The present invention relates to a method for automatically measuring a position shift, an attitude angle, and a dimension of an object for mounting an IC on a substrate.

[Prior Art] Various types of pattern recognition technology have been conventionally developed in order to automate work in a production factory. Such pattern recognition technology attempts to determine the shape of the object itself by some means, and the device used for pattern recognition is usually relatively complicated and expensive. .

However, when assembling work in various factories, for example, in assembling engines, batteries, fuel tanks, etc. to automobile bodies, assembling various parts to the body of home appliances, and assembling ICs to boards, etc., The pattern recognition technique as described above is not necessarily required. That is, the body of an automobile, the body of an electric home appliance, the IC substrate, etc., which is the target of recognition, etc., usually have a constant shape, so it is not necessary to determine their shape again, but simply the recognition target It suffices to measure the displacement of the object with respect to the reference position and the inclination of the attitude angle with respect to the reference attitude, and it is often the case that products of different sizes are mixed. Is sufficient, which makes it possible to significantly simplify the device itself and provide it at low cost.

[Problems to be Solved by the Invention] An object of the present invention is to attach a simple mark to an object without using a general pattern recognition technique in the assembling work in the above-mentioned factory and to perform it. It is to make it possible to measure the positional deviation, the attitude angle and the dimension by using a simple and inexpensive device by utilizing or by using a reference hole or the like instead of the mark.

[Means for Solving the Problems] In order to achieve the above-mentioned object, in the measuring method of the present invention, the posture and the dimension are set at a separated position on the object to be measured,
Three reference marks of arbitrary shape are attached, and on a plurality of objects with different dimensions, at least two of the reference marks used for dimension measurement are separated by different distances according to the object. The coordinates of the barycentric position of each reference mark are measured from the image of the object obtained by the image input device arranged at a distance, and the two adjacent marks selected from these three reference marks are selected. The posture angle of the target object is calculated by calculation based on the coordinate value of the center of gravity position, and the position shift of the target object is calculated by calculation based on the coordinate value of the center of gravity position of the two marks selected from the three reference marks. , And for dimension measurement on an object having different dimensions by calculation based on the barycentric position of one reference mark arbitrarily selected from the three reference marks, the posture angle calculated above, and the positional deviation Measuring the coordinate axis of the distance between the reference marks, it employs a technical means that.

[Effect of the Invention] According to the measuring method of the present invention as described above, it is not necessary to perform complicated processing on the image of the object obtained by the image input device, and each reference can be obtained from the image by simple processing. By measuring the coordinates of the barycentric position of the mark and performing a simple calculation based on those coordinate values and the like, it is possible to easily measure the positional deviation of the object, the posture angle, and the size of the reference portion.

Further, since it is possible to easily measure in this way, not only is it easy to implement a device for processing an image signal from the image input device as hardware, but also real-time processing of the image signal becomes possible. Therefore, it is very suitable for use in a factory production line.

[Examples] The method of the present invention will be described in more detail below with reference to the drawings.

As shown in FIG. 1, an xy coordinate system having an origin O at the center of the object A _{0 at} the reference position is now set in the space in which the measurement object A regarding the positional deviation, posture angle, and dimensions exists. To do. The measurement object A may be, for example, a two-dimensional view of the inside of the hood of an automobile, the body of the automobile, or an IC substrate or the like. Further, here, in order to simplify the description by the following mathematical formula, the object A at the reference position is the origin of the xy coordinate system.
The case where the origin is set to the center will be described, but the origin can be set to an appropriate position.

In the present invention, it is assumed that a plurality of large and small objects are mixed as the object A, and three reference marks 1, 2, and 3 are provided on each of the objects. Of these reference marks, the reference marks 1 and 2 are provided at positions symmetrical with respect to the y-axis of the xy coordinate system, and the reference mark 3 is with respect to the center of the reference mark 1 and the object A. Although they are provided at positions symmetrical with respect to a point, they are not necessarily limited to such an arrangement, and can be provided at appropriate positions within the range of various restrictions described later.

The plurality of objects having different sizes, or at least the reference marks on the plurality of objects having different sizes of the reference position of the product, are preferably installed at similar positions according to the size of the product, but at least The two reference marks used for the dimension measurement may be arranged at different distances under a certain restriction such as disposing the two reference marks at similar positions according to their sizes. Further, it is desirable in terms of measurement accuracy that the positions of the reference marks 1, 2, and 3 are provided at intervals as far as possible within a range that does not interfere with the image input device described later. Furthermore, the shape and size of each of the reference marks can be selected as appropriate.

These reference marks 1, 2, and 3 can be drawn by a paint on the object A, or can be attached by attaching a label to the object A.
The tangible object above, such as the head of a bolt or an existing hole, can be used as it is as the reference mark. However, it is desirable to prevent erroneous recognition that there is no similar shape around it, and if they are unavoidable, use colored marks to facilitate classification. Is effective.

When the object A is transferred by a belt conveyor or the like and reaches the measurement range of the posture and dimensions, as shown in FIG. 1, there is an arbitrary amount of positional deviation with respect to the reference position and an arbitrary amount of posture angle inclination. ing. That is, the center of the object A is Δx in the x-axis and y-axis directions with respect to the origin O of the coordinate system.
And Δy, and is inclined by an angle θ with respect to the reference posture of the object.

Therefore, for the above measurement, first, an image input device such as an ITV camera captures the reference marks 1, 2, and 3 as images. This image input device may use a common one for each of the reference marks 1, 2 and 3, but may be used individually for each mark, in which case the image input device is placed close to the reference mark. By taking an image by performing the imaging, the resolution can be increased and the measurement accuracy can be improved.

In this way, the image signal of the reference mark input by the image input device is processed by the image processing device to measure the barycentric positions P ₁ , P ₂ and P ₃ of the reference marks ₁ , _2, and _3. It The measurement of the position of the center of gravity can be easily performed by a known means, but an example thereof will be briefly described. If the reference mark is placed on the XY rectangular coordinate system, the coordinates of the position of the center of gravity will be described. (XG, YG) is The calculation device for performing this calculation may be connected to the image input device. However, ds is a minute area of the figure.

The barycentric position P ₁ , of the reference marks 1, 2 and 3 measured by the above
P ₂ and P ₃ have coordinates when viewed from the xy coordinate system, respectively, P ₁ (x ₁ , y ₁ ), P ₂ (x ₂ , y ₂ ), P ₃ (x ₃ , x ₃ ), their coordinate values are Represented by

At least one of W and H in the above equation is a dimension used as a reference for distinguishing a plurality of types of objects on the object A at the reference position, and W is two reference marks 1 and a reference mark. 2 or 3 separation distance in the x-axis direction, H
Is a separation distance in the y-axis direction between the two reference marks 1 or 2 and the reference mark 3.

Therefore, γ = (y ₁ −y ₂ ) / (x ₂ −x ₁ ) is defined, and the coordinate value P ₁ (x ₁ , y ₁ ), P of the barycentric position measured for the adjacent reference marks 1 and 2 is defined. _When calculated and arranged from ₂ (x ₂ , y ₂ ), γ = −tan θ, and from this equation, θ can be obtained from θ = tan ⁻¹ (−γ).

The value of γ represents the inclination of the straight line connecting the barycentric positions of the two reference marks, and it is necessary that this γ be calculated independently of W and H. When attached, it is necessary to install them at a position where γ can be calculated independently of W and H.

Further, the positional deviations Δx and Δy of the center position of the object A in the x-axis and y-axis directions are the coordinate values P ₁ (x ₁ , y ₁ ), P ₃ (x of the center of gravity measured with respect to the reference marks 1 and 3. ₃ , y ₃ ), It can be obtained by a simple calculation.

Of course, this positional deviation can be relatively easily obtained from the coordinate values of other reference marks.

The barycentric position of the reference marks 1 and 2 is not at the coordinates (x ₁ , y ₁ ), (x ₂ , y ₂ ) and (x ₃ , y ₃ ) in the xy coordinates but at the reference position. The relative position of the reference mark on the object A with respect to the center of gravity, that is, the positional deviations in the x-axis and y-axis directions (dx ₁ , dy ₁ ), (dx ₂ , dy ₂ ), (dx ₃ ,
dy ₃ ) can also be obtained, and the above Δx and Δy can be similarly easily obtained by these values.

Further, since the reference dimensions for distinguishing large and small types of objects, that is, the values of W and H are known from the above-mentioned values of Δx, Δy, and θ, for example, the center of gravity of the reference mark 2 is determined. Position coordinates, The basis, W = 2 {- (X 2 cosθ + Y 2 sinθ) + (Δxcosθ + Δysinθ)} H = 2 - can be obtained by _{{(X 2 sinθ + Y 2} cosθ) + (Δxsinθ + Δycosθ)}.

As is clear from the above description, the position shift, posture angle and dimension of the object can be easily measured by simple calculation, and such calculation is performed by using the barycentric position P of the reference marks 1, 2 and 3. It can be realized by connecting a simple arithmetic circuit to the image processing apparatus for measuring ₁ , P ₂ and P ₃ .

As described above in detail, according to the automatic measuring method of the present invention, in the assembling work and the like in which the shape of the object is predetermined, the object is not complicated and expensive and the pattern recognition technique is not used. It is possible to easily and inexpensively measure the misalignment, posture angle, and dimension by using the reference mark attached to the object without performing complicated processing on the image, and process the image signal. The device can be easily implemented as hardware, and the real-time processing of the measurement can be performed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a measuring method according to the present invention. 1,2,3 …… Reference mark, A …… Target object.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeo Toda 4-7-1 Kajiwara, Kamakura City, Kanagawa Prefecture Nomura Research Institute, Ltd. (56) Reference JP-A-59-81768 (JP, A) JP-A-SHO 60-165503 (JP, A)

Claims (1)

[Claims] 1. Three reference marks of arbitrary shape are attached at spaced positions on an object whose posture and dimensions are to be measured, and on a plurality of objects having different dimensions, of the reference marks, At least two reference marks used for dimension measurement are arranged at different distances according to the object, and the coordinates of the barycentric position of each reference mark are measured from the image of the object obtained by the image input device. , The posture angle of the object by calculation based on the coordinate values of the barycentric positions of two adjacent marks selected from these three reference marks,
The displacement of the object is respectively measured by calculation based on the coordinate values of the barycentric positions of the two marks selected from the above three reference marks, and one selected arbitrarily from the three reference marks. The object characterized by measuring the distance in the coordinate axis direction between the reference marks for dimension measurement on the object having different dimensions by the calculation based on the position of the center of gravity of the reference mark, the posture angle calculated above, and the positional deviation Method of automatic measurement of posture and dimensions.