JPH0145002B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field to Which the Invention Pertains) The present invention relates to a device for detecting the position of a moving object using a photoelectric method.

(Problem to be solved by the invention and its characteristics) The position of the moving object is detected by emitting a laser beam from a fixed light source to a light receiving plate installed on the moving object and detecting the position of the irradiation point using a photoelectric element. The technology is known.

Then, on the radius of a disk rotating at a constant speed,
The distance from the laser beam irradiation point to the center of the disk is detected by arranging multiple light receiving and detecting elements that each emit a different signal depending on the distance from the center of the disk, and also detecting the baseline of the light receiving and detecting element when receiving light. There is a conventional example in which the rotational displacement angle from
This conventional example has the disadvantage that the accuracy of detecting the distance from the laser beam irradiation point to the center of the disk depends on the number of light receiving detection elements, and if you try to improve the accuracy, the number of light receiving detection elements and signal lines increases. There is.

The object of the present invention is to provide a photoelectric position detection device for a moving object that does not have the drawbacks of the conventional example, and its structural features are as described in the claims. be.

That is, the device of the present invention detects the distance from the laser beam irradiation point to the center of the disk based on the light reception time of the rod-shaped photodetector (the length of the light reception signal emitted when the photodetector crosses the laser beam irradiation point). The light receiving signal from the photodetector can be sent to the arithmetic unit through one signal line.

(Explanation with drawings) A disk 1 is rotatably installed at a suitable location on a moving object (for example, a shield for tunnel excavation) (not shown) via a rotating shaft 4, and a rod-shaped photodetector 2 is arranged on the radius of the disk 1. is installed.

Although not shown, a light beam source is installed at a fixed point (for example, the ceiling of a tunnel) and emits a beam toward the disk 1 which is rotating in one direction at a constant speed.

When the photodetector 2 crosses the irradiation point P of the laser beam, the photodetector 2 emits a light reception signal, and this light reception signal is sent to an arithmetic unit (not shown) via a signal line 3 and a slip ring 5. There is.

Since the moving speed of a point on the rotating disk 1 is proportional to the distance from the center O of the disk 1, the light reception time of the photodetector 2 is inversely proportional to the distance r from the irradiation point P to the center O. Therefore, the distance r can be calculated based on the length (light reception time) of the light reception signal emitted by the photodetector 2, and this calculation is performed by the arithmetic unit.

On the other hand, in the illustrated embodiment, a rotary encoder 6 is provided as a means for detecting the rotation angle θ of the photodetector 2 from the base line OX when the photodetector 2 emits a light reception signal, and its detection signal is also It is now sent to the arithmetic unit.

In this way, the position of the irradiation point P can be determined using polar coordinates (r, θ) with the center O of the disk 1 as the coordinate origin, but the position of the moving body can be determined from the position of the irradiation point P, for example. , may be the same as the conventional example,
The calculations necessary for this can be performed by the arithmetic unit.

(Effects of the Invention) The device of the present invention is as described above, in which a single rod-shaped light beam moves across the laser beam irradiation point to change the distance from the laser beam irradiation point to the center of the disk. Since detection is performed based on the light receiving time of the detector, there is an advantage that only one signal line is required for the photodetector.

[Brief explanation of drawings]

The drawings are main part diagrams of one embodiment of the present invention, and the first
The figure is a front view of the disk, and FIG. 2 is a plan view showing how the disk is installed. In the figure, 1: disk, 2: photodetector, 3: signal line, 4: rotating shaft, 5: slip ring, 6: rotary encoder.

Claims (1)

[Claims] 1. A disk that is installed on a moving body to rotate at a constant speed and has a rod-shaped photodetector attached to its radius, a fixed light source that irradiates the disk with a laser beam, and the photodetector. A computing unit that calculates the distance from the irradiation point of the laser beam to the center of the disk based on the light reception time, and a means for detecting the rotation angle from the base line of the photodetector at the time of light reception. A position detection device for a moving object.