JPS6341489B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting the position of a moving object such as a vehicle, a ship, or an aircraft, and more particularly to a method for detecting the position of a moving object using a laser beam.

Several conventional methods for detecting the position of moving objects using radio waves have been put into practical use, but all of these methods require large-scale equipment and cannot be easily detected in any location. The drawback was that it could not be implemented.

In addition, position measuring devices using lasers have been put into practical use, but these measuring devices measure the position of a fixed point that is almost stationary, and do not measure the instantaneous position of a moving object one after another. It wasn't.

Therefore, we installed a laser light source that sequentially emits laser beams in different directions on a moving object, and measured the acceptance angle of the reflected light that was reflected back from three corner cube prisms installed at predetermined positions. , a system for measuring the position of the moving object has been considered based on the principle of triangulation.

With this system, the position of a moving object can be easily measured using one laser light source and three corner cube prisms with a simple structure, but since the laser light source is installed on the moving object, Accurate position measurement is extremely difficult.

In other words, while measuring the acceptance angle of the reflected light from the three corner cube prisms, the moving object serving as the measurement point moves, making it impossible to accurately measure the position. Due to the inclination and vibration of the body, the laser beam could not be applied to the corner cube prism, resulting in the inconvenience that reliable position measurement could not be performed.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a method for detecting the position of a movable body that can reliably and accurately detect the position of the movable body.

In order to achieve the above object, the method for detecting the position of a moving object according to the present invention includes a sequence in which the scanning speed of the laser light source emitted from the laser light source in the horizontal direction is performed at low speed rotation for the first time and at high speed rotation for the second time. The laser beam is repeatedly rotated, and the scan angle in the vertical direction of the laser beam is increased during the first low-speed rotation, and the scan angle in the vertical direction is decreased during the second high-speed rotation.

Due to the above characteristic structure, the following excellent effects have been achieved.

In other words, when emitting laser beams in different directions one after another, the first time the laser beam is scanned vertically and then horizontally at a low speed to ensure that the laser beam is emitted by the corner cube prism. The vertical direction range in which each corner cube prism exists is detected in advance and memorized so as to be reflected.
The second time, the vertical scanning angle of the laser beam is made small based on the memorized vertical direction range, and the scanning is performed at high speed in the horizontal direction, so in both cases, the circumferential speed is high overall. The light reception time of the corner cube prism can be kept relatively long regardless of the angle of the corner cube prism, and the reflected light from the corner cube prism can be reliably received, and three horizontal direction light reception angle information with little time difference between the two times can be obtained. This made it possible to detect the position of a moving object more accurately.

In other words, since the above-mentioned second horizontal laser beam scan is performed at high speed, the effect of the distance traveled by the moving object during this time can be minimized to the extent that it can be ignored on the position measurement accuracy. .

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a lawnmower V, which is an example of a moving object.
A lawn mower 4 has a disc-shaped cutting blade installed in the middle part of a vehicle body 1 having front wheels 2, 2 and rear wheels 3, 3.
is suspended so as to be vertically movable, and a laser light source A having a configuration described later is provided on the upper part of the vehicle body 1.

The laser light source A, as shown in FIG.
The laser beam emitted from the laser emitter 5 is configured to be scannable vertically over a range of a predetermined angle θ by an optical scanner 6, and can be rotated in a horizontal plane by D and C motors 7. It is placed on a rotating table 8.

The laser emitter 5 is also provided with a light receiver 9 that receives reflected light from the corner cube prisms B, C, and D, with its light receiving surface facing the direction in which the laser beam is emitted. Integrally, the optical scanner 6 and the motor 7
The direction of the optical axis can be changed by changing the direction of the optical axis. A rotary encoder 10 is attached to the motor 7 to detect the azimuth angle θ indicating the direction in which the laser beam is emitted.

Then, the entire laser light source A is
1 is fixed to a supporting frame 12,
This support frame 12 is attached to the vehicle body 1 via a damper member 13 made of an elastic material such as rubber, and prevents vibrations and shaking of the vehicle body 1 from being transmitted to the laser light source A. The laser light source A is configured to always remain horizontal.

The optical scanner 6, as shown in FIG.
The axis P of the rotor 17 is located at the center of the magnetic force of
An optical mirror 18 is fixed on the top, and a position where the rotational force generated in response to the strength of the current I flowing through the drive winding 14 and the torsional torque of the control spring 19 attached to the rotor 17 are equal. The rotor 17, ie, the optical mirror 18, is configured to remain stationary.

The laser beam emitted from the laser emitter 5 is reflected in a predetermined direction by an optical mirror 18 provided on the axis P of the rotor 17, and the direction of reflection is determined by the input current of the drive winding 14. It is controlled in any direction by I.

Hereinafter, a system for measuring the position of the lawn mower V using the laser light source A having the above configuration will be explained.

As shown in FIG. 4, corner cube prisms B, C, and D as ground facilities are installed at three fixed points, and a laser light source A installed on the lawnmower V is used as an optical scanner 6 as described above. Therefore, a laser beam is emitted that scans in a horizontal plane while scanning vertically at a predetermined angle θ. When the laser beam hits the corner cube prisms B, C, and D, it travels in the opposite direction, returns to the light source A from which the laser beam was emitted, and is received by the light receiver 9. Then, the rotary encoder 10 detects the directions θ ₁ , θ ₂ , θ ₃ of the photo receiver 9 at the time when each of the laser beams is received by the photo receiver 9 , and the detected directions θ ₁ , θ ₂ , θ ₃ are detected by the rotary encoder 10 . Based on this, the position P of the lawn mower V is calculated based on the principle of triangulation.

On the other hand, as described above, the driving current of the optical scanner 6 at the time when the light receiver 9 receives the reflected light from the corner cube prisms B, C, and D during the first horizontal scan of the laser light source A. By sampling I ₁ , I ₂ , I ₃ ,
The positional relationship (scan angle in the vertical direction) between the laser light source A and the corner cube prisms B, C, and D in the vertical direction is measured in advance.

Then, during the second scan in the horizontal plane,
Detection direction θ ₁ of the rotary encoder 10,
In the near future of θ ₂ and θ ₃ , the sampled drive current
A slight deviation is added to I ₁ , I ₂ , and I ₃ to drive the optical scanner 6 with a current to ensure that the laser beam hits the corner cube prisms B, C, and D.

[Brief explanation of the drawing]

The drawings show an embodiment of the method for detecting the position of a moving object according to the present invention, and FIG. 1 is an overall side view of a lawn mowing vehicle;
Figure 2 is a schematic diagram showing the configuration of the laser light source, Figure 3 is a schematic diagram showing the configuration of the laser light source.
This figure is a schematic diagram showing the configuration of the optical scanner, and FIG. 4 is an explanatory diagram of moving body position detection. V...Moving object, A...Laser light source, B, C,
D... Corner cube prism, θ ₁ , θ ₂ , θ ₃ ...
...azimuth angle, θ...scan angle.

Claims (1)

[Claims] 1 Laser beams are emitted sequentially in different directions from a laser light source A provided on a moving body V, and are reflected back by at least three corner cube prisms B, C, and D provided at predetermined positions. is received by the light receiver 9 provided on the light source A, and by measuring the direction of the laser light source A at that time, each azimuth angle θ ₁ , formed by the laser light source A and the corner cube prisms B, C, and D is determined. This is a position detection system for a moving body that measures the position of a moving body V from θ ₂ and θ ₃ , and the scanning speed in the horizontal direction of the laser beam emitted from the laser light source A is determined by rotating at a low speed the first time and by rotating at a low speed the second time. As well as repeating the sequence of high-speed rotation,
A method for detecting the position of a moving body, characterized in that during the first low-speed rotation, the vertical scan angle θ of the laser beam is made large, and during the second high-speed rotation, the vertical scan angle θ is made small.