KR19980039635A - Omnidirectional Coaxial Imaging Device Using a Conical Mirror Pair - Google Patents

Abstract

The present invention relates to an omnidirectional coaxial image pickup device using a pair of cone mirrors in which the image of the assembly is coaxially picked up in all directions using a cone mirror pair to analyze the relative error during assembly. will be. Conventionally, since it was not suitable to obtain omnidirectional error information necessary for assembling a component having a complicated cross section, a measuring device for simply measuring an omnidirectional error was required. The present invention is a principle that the image of the assembly and the object to be assembled is reflected to the cone mirror pair and then incident to the camera through a pair of plane mirror, because the cone mirror can cover the omnidirectional direction of the assembly object omnidirectional image of the object Can be obtained. The apparatus of the present invention can be used for automatic PCB insertion, small device component assembly, semiconductor chip surface mounting, and the like.

Description

Omnidirectional Coaxial Imaging Device Using a Conical Mirror Pair

The present invention relates to an image pickup device for a component assembly machine. More specifically, the present invention omnidirectional coaxial image using a pair of conical mirrors to analyze the relative error during assembly by capturing the image of the assembly object in all directions coaxially using a pair of conical mirrors. It relates to an imaging device.

Part assembly is a positioning process as a step in the manufacturing process. Errors such as position or angle that occur during assembly work cause very large reaction forces between the assembly parts, which hinders assembly and often damages the robot or parts. In order to overcome this difficulty, the position and angle error between the assembly parts should be corrected, and the measurement is most important when the error is corrected. In the case of a component having a simple symmetrical cross section, it is possible to analyze the circumferential error by using local error information alone. Is needed. Therefore, there is a need for a sensor that can easily measure errors in all directions, not only for simple symmetrical components but also for complex asymmetrical shapes.

Conventionally, there are two main methods for measuring an error using a visual sensor. One is the camera fixing method as in FIG. 1 and the other is the camera repositioning method as in FIG.

The camera fixing method is a method of measuring error information on relative positions and postures between assembly parts by installing a camera at a fixed position as shown in FIG. However, in this method, since the viewing angle is fixed, it is inevitable to generate an occlusion area in which the assembly object opposite to the assembly object is not visible. Therefore, the error in the front direction of the assembly parts is not known, and only partial error information on the direction facing the installation direction of the camera is obtained, so that the application of the complicated object is difficult.

The camera repositioning method is a method of obtaining omnidirectional information by varying the imaging angle by increasing or relocating the number of sensors (here, cameras) as shown in FIG. 2 to overcome the problem of blind spots. However, this method increases the cost and installation space according to the increase in the number of sensors, or increases the amount of movement and information processing due to the reorientation of the direction and position of the sensor. have.

Yasushi Yagi et al. Has proposed a device that can be used to drive a mobile robot by capturing an image of the surrounding environment from the sensor outward using a single outer cone mirror and a camera (see Yasushi). Yagi et al., IEEE Trans. On Robotics and Automation, 10 (1), 1994), which do not relate to machinery for assembly of parts.

As described above, the conventional method is not suitable for obtaining omnidirectional error information necessary for assembling a component having a complicated cross section, and thus a measuring device for measuring an omnidirectional error is required.

Accordingly, the present inventors have diligently researched to solve the problems of the conventional device assembly error measuring device, and as a result of measuring the error occurring when assembling the part, the conical mirror pair and the flat mirror pair are used to 360 ° around the part. By imaging the omnidirectional coaxial image of, it has been confirmed that the omnidirectional error can be quickly measured without the blind area, thereby completing the present invention.

After all, it is an object of the present invention to provide an omnidirectional coaxial imaging device capable of imaging an omnidirectional coaxial image of an assembly using a pair of conical mirrors and a flat mirror pair.

1 is a perspective view showing a conventional camera-fixed imaging device.

2 is a perspective view showing a conventional camera repositioning imaging device.

3 is an assembly view showing the omnidirectional coaxial imaging device according to the present invention, where (a) is a left side view, (b) is a front view, and (c) is a right side view.

4 is an exploded perspective view showing the concept of the present invention.

5 is a diagram for theoretically explaining the concept of the present invention.

6 is a diagram showing an example of an image of an object measured using the omnidirectional coaxial image capturing apparatus according to the present invention.

Explanation of symbols for main parts of the drawings

1: camera 2: camera control unit

3: lens 4: first plane mirror

5: mirror second mirror 6: outer conical mirror

7: inner cone mirror 8: transparent plate

9: shock absorber 10: gripper

11: Assembly parts (eg peg) 12: Assembly target parts (eg hole)

11 ': Peg image 12': Hall image

13: annular LED light 14: halogen light

15: Robot tip 16: Force / torque sensor

Hereinafter, with reference to the accompanying drawings, the configuration and operation of the omnidirectional coaxial image pickup device (hereinafter, abbreviated as "the device of the present invention") using a cone mirror pair according to the present invention will be described.

3, the apparatus of the present invention includes a gripper (10, gripper) for picking up the component (11) to be assembled to the component to be assembled (12); A compliant unit 9 for damping vibrations according to the operation of the apparatus of the present invention; A transparent plate 8 installed horizontally on an upper portion of the buffer part 9; An annular conical mirror (7, hereinafter referred to as an "inside conic mirror") formed on the transparent plate (8) and having a reflecting surface formed therein; A conical mirror (6, hereinafter referred to as an "outside conic mirror") having a reflective surface formed on the outer surface thereof, coaxially installed in the inner conical mirror 7; A first flat mirror 4 installed on the inner conical mirror 7; A second flat mirror 5 installed at a position opposite to the first flat mirror 4; And a lens 3 and a camera 1 provided vertically above the second plane mirror 5. In the apparatus of the present invention, lighting devices 13 and 14 are placed underneath the transparent flat plate 8 so as to compensate for the amount of light incident on the camera 1 and to avoid shadows around the parts 11 and 12. The second flat mirror 5 is attached to the rear surface of the second flat mirror 5 so that the second flat mirror 5 can be finely moved in the 45 ° direction. In addition, a fine adjustment unit 2 for maintaining the position and posture of the camera 1 at six degrees of freedom is attached to the side of the camera 1.

In FIG. 3, reference numeral “15” denotes a robot end-effector and “16” denotes a force / torque sensor.

In the above configuration, the transparent plate (8) serves to transmit the image of the objects (11, 12) to the reflective surface of the inner conical mirror (7) while supporting the inner conical mirror (7) and outer conical mirror (6). However, it is preferable to use a solid transparent acrylic plate as the transparent flat plate 8. The shock absorbing portion 9 is made of an elastic member such as a spring, and serves to attenuate interference and vibration between machines in the vertical direction.

In the apparatus of the present invention, in order to deepen the depth of the lens 3 and reduce the influence of spherical aberration or the like, it is preferable to make the aperture of the lens as small as possible to make it as a pin-hole. However, at this time, since the amount of light incident on the camera 1 is insufficient, the light source shining on the component needs to be very bright. In addition, it is important to prevent the shadow of the object because the omnidirectional image must be captured. Therefore, double lighting apparatuses were used as the lighting apparatuses 13 and 14. One is an annular lamp 13 using high brightness LEDs, and the other is four halogen lamps 14 arranged at right angles to each other. The halogen lamp 14 is installed so as to be able to move in the vertical direction within the range of 0 ~ 90 °, this lighting device is also preferably adjusted automatically the brightness and irradiation angle in consideration of the reflectance of the parts.

Hereinafter, the operation of the apparatus of the present invention configured as described above will be described with reference to the accompanying drawings. FIG. 4 is a conceptual diagram showing the basic principle of the apparatus of the present invention, which shows that an omnidirectional coaxial image of an assembly can be obtained by using a pair of cone mirrors 6 and 7 and a pair of plane mirrors 4 and 5, and FIG. FIG. 5 shows a myriad of fine planar mirror models for explaining that an omnidirectional image can be obtained by the inner cone mirror 7, and FIG. 6 is a measurement example of the omnidirectional coaxial image of the assembly taken by the apparatus of the present invention. Is a picture.

First, with reference to FIG. 4 and FIG. 5, the basic principle of the apparatus of this invention is demonstrated.

4, the image of the assembly 11 and the object to be assembled 12 is reflected by the inner conical mirror 7 and then by the outer conical mirror 6 to reflect the first and second flat mirrors 4 and 5. It can be seen that the incident to the camera 1 through. Intuitively, it can be seen that the inner cone mirror 7 can cover the omnidirectional direction of the assembly 11 and the assembly object 12 so that an omnidirectional image of the object can be obtained. That is, since the inner and outer conical mirrors 7 and 6 have the same effect as the infinitely arranged plane mirrors on a circumference of a certain size, the surroundings of the measurement object can be seen without a square through them.

The reason for installing the flat mirror pairs in addition to the conical mirror pairs is a problem of mechanical mounting, and since the camera 1 cannot be installed in the vertical coaxial direction with the inner and outer conical mirrors 7 and 6, The position is shifted to one side and the first and second plane mirrors 4 and 5 are used to change the light path.

Under this concept, the principle of the apparatus of the present invention will be explained theoretically with reference to FIG. If, as in Figure 5, X²+ Y²= R²On the circumference represented by the circle, the width is ΔW = γΔφ and the normal vector is

Assume that N (= 2π / φ) small planar mirrors are installed at intervals of φ. In this case, the effect of photographing can be obtained with different angles. However, since a finite mirror arrangement, blind spots occur between the mirror and the mirror.

Therefore, in order to remove this blind spot, the mounting interval is set to φ = Δφ and the circumferential plane mirror number is If you increase the width, eventually Infinite mirrors are arranged in an endless array on the circumference. As a result, the placement of this mirror is normal

And a cone mirror with a vertex angle of α. In Fig. 5, the half width of the cone angle of the cone mirror is represented by α / 2.

According to this principle, the device of the present invention used an annular truncated mirror as an inner cone mirror. As a result, the circumferential shapes of the assembly 11 and the assembly object 12 are projected onto both inner mirror mirrors 7 surrounding these components 11 and 12, and the omnidirectional image as shown in FIG. (2π image) can be obtained. Referring to FIG. 6, it can be seen that two images, eg, a peg image 11 ′ and a hole image 12 ′, are shifted by a predetermined angle. Instead of processing these two-dimensional images, the estimation of the error from these projection images is divided into Ν _line (= 2π / φ) radial lines corresponding to a specific azimuth angle φ with respect to the center. This can be done simply by analyzing the one-dimensional image of the image.

Finally, the operation of the apparatus of the present invention is summarized with reference to FIG. When the device of the present invention is mounted and operated on the robot tip 15, the gripping portion 10 picks up the parts 11 to be assembled. It can be controlled by a control device (not shown) via the robot tip 15 of the device of the invention. The images of the assembly part 11 and the object to be assembled 12 are reflected by the inner conical mirror 7 and then reflected by the outer conical mirror 6 therein, so that the first flat mirror 4 and the second flat mirror are The path is changed by (5) to enter the camera 1 through the lens 3.

The image incident on the camera 1 is converted into an image signal and processed into an analysis device (not shown). The analysis device is connected to the device of the present invention (on-line) to perform the error analysis at the same time as the assembly operation.

Structurally, it can be seen from FIG. 6 that the inner and outer conical mirrors 7 and 6 and the assembly parts 11 and 12 are coaxial with each other, but the camera 1 is laterally biased from them. . However, since the optical axis of the camera 1 becomes the same as the optical axis of the inner and outer conical mirrors 7 and 6 and the assembly parts 11 and 12 by the first and second plane mirrors 4 and 5, eventually. Since the above elements are all coaxially located, a coaxial image can be obtained by the apparatus of the present invention.

As described above, while the apparatus of the present invention is in operation, light is emitted to the assembly parts 11 and 12 using the lamps 13 and 14 to increase the amount of light entering the camera 1 and to surround the assembly parts 11 and 12. To suppress shadow formation. In addition, the camera adjusting unit 2 is operated to finely adjust the position and posture of the camera 1, which may be adjusted manually but is preferably electronically controlled. The second flat mirror 5 can also be moved by the fine adjustment 17 to finely adjust its position, which is also preferably controlled automatically. Interference or vibration between the mechanical elements generated by the operation of the apparatus of the present invention can be alleviated by the buffer 9 to achieve more accurate image measurement.

On the other hand, as another application of the device of the present invention, since the distortion of the image formed on the inner surface mirror mirror 7 occurs according to the height of the object under measurement, analyzing the distortion degree can calculate the distance to the object. Gripping can be facilitated. In addition, since the height of the assembly varies depending on the component, it is preferable that the lens has an auto zoom and auto focusing function. As such, it will be apparent to one of ordinary skill in the art that the basic principles of the present invention are not limited to the devices of the present invention.

As described above, according to the apparatus of the present invention, the relative error between the assembly parts can be analyzed by one imaging over 360 ° without a rectangular area, and only one-dimensional image processing is performed instead of two-dimensional image processing. Since error estimation is possible, there is an effect that the error processing can be performed at a short time even in a component having a complicated cross section. In addition, since the distance to the assembly can be estimated, the assembly of the assembly can be gripped easily and accurately.

The apparatus of the present invention makes it easy to assemble an assembly having a complex asymmetric cross section, to automatically insert a component into a printed circuit board (PCB), and to assemble a surface mount component (SMD) in a semiconductor field. In addition, since the image obtained by the apparatus of the present invention is a coaxial image, it is easy to convert the measured image information into the movement information of the robot, and there is an effect that the error can be corrected online at the same time as the work.

Claims (10)

Holding means for picking up an object assembled to a specific object; A transparent flat plate installed horizontally on the holding means; An inner surface mirror having an annular truncated cone shape having a reflection surface formed on the inner surface of the transparent flat plate; An outer surface mirror having a reflection surface formed on an outer surface thereof coaxially with an inner central axis of the conical mirror; A first planar mirror mounted on the truncated mirror; A second planar mirror installed at a position opposite to the first planar mirror; And a visual sensing means provided vertically above the second plane mirror. The omnidirectional coaxial imaging apparatus according to claim 1, further comprising illumination means provided on a side of the gripping means to emit light to an assembly object. 3. The omnidirectional image capturing apparatus according to claim 2, wherein the lighting means comprises an LED and a halogen bulb. 4. The omnidirectional coaxial imaging apparatus according to claim 3, wherein the LED forms an annular light, and the halogen bulbs are arranged at right angles to each other and move vertically in a range of 0 to 90 degrees. The omnidirectional coaxial imaging apparatus according to claim 1, wherein the gripping means comprises a gripping portion for picking up an assembly object and a buffer portion for attenuating interference and vibration between machines in the vertical direction. The apparatus of claim 4, wherein the buffer part has an elastic structure. The omnidirectional coaxial imaging apparatus of claim 1, wherein the transparent flat plate is a transparent acrylic plate. The omnidirectional coaxial image capturing apparatus of claim 1, wherein the second planar mirror includes a fine adjustment unit and is finely adjusted. The omnidirectional coaxial imaging apparatus according to claim 1, wherein the visual sensing means comprises a lens, a camera for processing an image coming through the lens, and an adjusting unit for adjusting the position and attitude of the camera. The omnidirectional coaxial image capturing apparatus of claim 9, wherein the lens has auto zoom and auto focusing functions.