JP3068325B2 - 3D position measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional position measuring device used for controlling an industrial robot or the like.

[0002]

2. Description of the Related Art In an industrial robot, when performing its work, it is necessary to measure the position of a tip portion with a tool or a hand and move the tip portion of the robot to a target location. At this time, the simplest method is to measure the rotation angle of each joint of the robot and obtain the position of the tip from the information. However, in this method, deflection occurs due to the weight of the robot itself, and accurate position calculation may not be performed.

Therefore, conventionally, as shown in FIG. 3, the position of the tip is measured using two television cameras 11 and 12. That is, the object 10 attached to the robot tip
Is captured by the first television camera 11 and the second television camera 12. The captured images are sequentially input to the image coordinate detector 4 by the switch 9. Image coordinate detector 4
Then, the position of the target object 10 on the captured image is detected.

In order to simplify the processing in the image coordinate detector 4, if an element such as a light emitting diode, which is sufficiently brighter than the surrounding environment, is used for the object 10, the area of the object 10 can be easily formed by the binarization processing. And is performed by determining the center of gravity of the region. The method of detecting the center of gravity is a known technique.

When the position of the object 10 on the image is detected from each of the two images, the distance between the positions is 2.
Since there is a parallax corresponding to the interval between the two television cameras 11 and 12, the coordinate calculator 6 uses
The three-dimensional position of the object 10 is calculated. This calculation method is a known technique. The calculated three-dimensional position is displayed on the display 7.
Will be displayed.

[0006] The television cameras 11 and 12 are mounted on the rotation mechanism 2, and the rotation mechanism 2 is rotated by the drive circuit 5 to change the orientation of the television cameras 11 and 12. The rotation angle of the rotation mechanism 2 is detected by the angle detector 3, and the detected rotation angle is sent to the coordinate calculator 6.

[0007]

However, according to the prior art, only the range in which both of the two television cameras 11 and 12 can capture an image can be measured. For this reason, when measuring the target object 10 whose position or movable range is unknown, it is necessary to provide the rotation mechanism 2 for rotating the two television cameras 11 and 12 so that the target object 10 can be searched for. Further, in order to calculate the three-dimensional coordinates, each of the television cameras 11 and 12 is required.
It is necessary to determine the position and the mounting angle in advance, but there is a problem that the calibration work becomes complicated because there are two television cameras.

An object of the present invention is to provide a high-precision three-dimensional position measuring apparatus which is simple in configuration and calibration work in view of the above prior art.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a configuration of the present invention comprises a rotating mechanism and a single unit which is rotated by the rotating mechanism and captures an image including an object every time a predetermined rotation angle is reached. A television camera, an angle detector for detecting a rotation angle of the television camera by a rotation mechanism, and an image for processing each output image output from the television camera for each imaging to detect a position of an object on the image A coordinate detector for calculating three-dimensional coordinates of the object from the position of the object on an image obtained for each image and the rotation angle of the television camera at the time of each image; It is characterized by the following.

[0010]

According to the present invention, the television camera is rotated by the rotation mechanism, and its imaging position is sequentially changed. At this time, an image is captured at an arbitrary rotation angle. Further, when an image is captured at another rotation angle, there is a parallax corresponding to the moved rotation angle between the image captured earlier and the image captured earlier. Therefore, when the position of the target on the captured image is detected by the image coordinate detector, the three-dimensional coordinates of the target can be obtained together with the rotation angle at that time.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

As shown in FIG. 1, in a three-dimensional position measuring apparatus according to an embodiment of the present invention, a television camera 1 includes a mounting jig 2.
2 attaches to the rotation mechanism 2. An angle detector 3 is connected to a rotation shaft of the rotation mechanism 2. The output image of the television camera 1 is connected to the image coordinate detector 4, and the position of the object 10 on the image is detected. As shown in an example of the prior art, a method of detecting a position on an image can be easily realized by using a well-known technique of binarization processing and gravity center detection when a light emitting diode is used for the object 10.

When detecting the position of the object 10 on the image, the image coordinate detector 4 issues a command to the drive circuit 5. The driving circuit 5 rotates the rotating mechanism 2 according to a predetermined moving amount.
To rotate. The coordinate calculator 6 calculates the three-dimensional coordinates of the object 10 from the outputs of the image coordinate detector 4 for a plurality of times and the respective output angles of the angle detector 3 when the images are captured.

The calculated three-dimensional coordinates are displayed on the display 7 and notified to the robot operator or directly to the robot controller to control the robot.

Next, the processing in the coordinate calculator 6 will be described in detail with reference to FIG. FIG. 2 shows an optical system according to the present invention. As shown in the figure, the world coordinate system 20, which is a reference for three-dimensional coordinates, is OXYZ, and the rotation axis of the rotation mechanism 2 is parallel to the Y axis.

On the rotation axis, in the lens of the TV camera 1
Heart O_VA point at the same height as the rotation center O_R(X_R, Y_R,
Z_R). Rotation center O_RHalf a rotation perpendicular to the rotation axis from
The center O of the lens at a position separated by the diameter L_VExists
become. The television camera 1 has a rotation angle θ of the rotation mechanism 2.
At 0 °, the center O of this lens _VCentering on the X axis,
Ω, φ, κ times about Y axis and Z axis respectively
It is assumed that the image is inverted.

At this time, a visual coordinate system 21 is defined by O _V xyz, where the z-axis is the direction opposite to the line of sight of the television camera 1, the x-axis is the horizontal direction of the imaging device 8, and the y-axis is the vertical direction. .
It is assumed that the image sensor 8 captures an image perpendicularly to the line of sight at a position separated by the screen distance C from the center O _{V of} the lens so that the line of sight passes through the center of the image sensor 8. In addition, the visual coordinate system 21 becomes θ around the rotation axis by the movement of the rotation mechanism 2.
Only rotate.

In the above optical system, the position (X ₀ , Y ₀ , Z ₀ ) of the center O _V of the lens is given by the following equation (1).

[0019]

(Equation 1)

The point P of the object is represented by (x _p ,
y _p , z _p ), and (X, Y,
Z), the following equation (2) holds.

[0021]

(Equation 2)

Here, the matrix A is as follows.

[0023]

(Equation 3)

The following equations (4) and (5) are obtained from the condition that the points P, p and O _V are on a straight line.

[0025]

(Equation 4)

Since the matrix A is a rotational coordinate transformation, the above equations (4) and (5) can be rewritten as the following equations (6) and (7).

[0027]

(Equation 5)

Since the above equations (6) and (7) are equations of a straight line passing through the points P and O _V , the position (x, y) of the object 10 on the image at the rotation angle θ of the rotation mechanism 2 ) For a plurality of sheets, the three-dimensional coordinates (X,
Y, Z) can be calculated.

[0029]

According to the present invention, the position of an object can be measured in the direction of 360 ° with respect to the rotation axis by using only one television camera, and the configuration of the apparatus is simplified.

Further, since only one TV camera is used, the calibration work is simplified and labor saving can be achieved.

Further, in the conventional method using two television cameras, since only two images can be used to calculate the three-dimensional coordinates of the object, the position of the object on the image is detected. Although it is easily affected by errors and it is difficult to improve the accuracy, according to the present invention, it is possible to calculate the three-dimensional coordinates of the target object using a large number of images, thereby canceling the position detection error on the images. Therefore, the industrial utilization effect is extremely large, for example, high accuracy can be achieved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a three-dimensional position measuring device according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining a method of calculating three-dimensional coordinates according to the present invention.

FIG. 3 is a configuration diagram showing a conventional three-dimensional position measuring device.

[Explanation of symbols]

 1, 11, 12 TV camera 2 Rotating mechanism 3 Angle detector 4 Image coordinate detector 5 Drive circuit 6 Coordinate calculator 7 Display 8 Image sensor 9 Switcher 10 Object 20 World coordinate system 21 Visual coordinate system 22 Mounting jig

Continuation of front page (56) References JP-A-5-314243 (JP, A) JP-A-4-62676 (JP, A) JP-A-63-92211 (JP, U) (58) Fields investigated .Cl. ⁷ , DB name) G01B 11/00-11/30 102 G06T 1/00 G06T 7/00 G06T 7/60

Claims (1)

(57) [Claims] 1. A rotation mechanism, one television camera which is rotated by the rotation mechanism and captures an image including an object each time a predetermined rotation angle is reached, and a rotation angle of the television camera by the rotation mechanism is detected. An angle detector, an image coordinate detector that processes each output image output from the television camera each time an image is captured, and detects a position of an object on the image, and an image detector that obtains each image. A three-dimensional position measuring device, comprising: a coordinate calculator for calculating three-dimensional coordinates of an object from the position of the object and each rotation angle of the television camera when each image is taken.