JPH04161814A - Two-dimensional position and direction measuring apparatus for moving object - Google Patents

Abstract

PURPOSE:To correct cumulative errors of an autonomous type running type while facilitating the building of a half-fixed path type guidance system by using a reflection target comprising two reflection mirrors in combination with a laser rotary projecting/receiving beam. CONSTITUTION:When an automatically conveying truck 1 as traveling straight from a position Q to R reaches the position R, an angle of a laser light incident into a target 2 is thetam2 and a photodiode 14 receives a laser light 15 reflected with a flat mirror 3B. A distance (d) to the position R from the position Q is determined with a wheel tachometer mounted on the truck 1. When this operation is utilized for a semi-fixed path type, a plurality of targets 2 (21, 22... and 2n) are arranged at a proper interval along a guidance path WO. If so, the truck 1 is corrected in direction from the position and direction (x, y, phi) determined at a first position/direction detecting point D1 and runs freely to the subsequent position/direction detecting point. In the utilization for an autonomous type, the position and direction as measured are replaced with those measured autonomously thereby enabling the deletion of cumulative errors.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a two-dimensional position and direction measuring device for a moving object, which is applied to guiding automatic guided vehicles used in various production lines and the like.

BACKGROUND OF THE INVENTION In recent years, automation in the manufacturing industry has progressed, and automation of position measurement of moving objects such as automatic guided vehicles in production lines has become very important. Furthermore, there are many moving objects that require non-contact position measurement.

Conventionally, for example, fixed route guidance systems such as electromagnetic induction and optical guidance have been adopted for guiding automatic guided vehicles.

Problems to be Solved by the Invention However, in the case of these fixed-route guidance systems, it is difficult to change the travel route, so it is important to put into practical use a semi-fixed route type or an autonomous traveling type that allows the travel route to be easily set and changed. is requested. Semi-fixed path types have been devised that use lasers or markers, but they are difficult to implement, and self-supporting types that use wheel rotation measurement or gyros have been devised, but All of these self-propelled types have a method of accumulating errors, so
It is necessary to periodically correct cumulative errors.

On the other hand, as shown in Japanese Unexamined Patent Publication No. 62-254007, the angle between three corner cubes placed apart from a moving object is conventionally measured using a laser beam.

A method of position detection has also been proposed, but in this case, a corner cube, which is a very expensive optical element, is used, so the problem is that the corner cube accounts for most of the material cost of this system. Also, by using three corner cubes, three angles must be measured.

The influence of measurement errors cannot be avoided.

The present invention was made in view of the above circumstances, and uses a reflective target consisting of two reflective mirrors instead of a corner cube to reduce costs and reduce the influence of errors in angle measurement. Therefore, it is an object of the present invention to provide a two-dimensional position and direction measuring device for a moving object that is compatible with semi-fixed path guidance systems and that can easily correct accumulated errors in self-propelled systems.

Means for Solving the Problems In order to achieve the above objects, 1) the moving object according to the present invention; 2)
The dimensional position and direction measuring device consists of a reflective target composed of two reflective mirrors perpendicular to the position measurement plane of a moving object, and a reflective target provided on the moving object that measures the two reflective targets by irradiating the reflective target with a laser beam. A rotating laser projector/receiver that receives the reflected laser beam from the reflecting mirror and detects the angle between the traveling direction of the moving object and the reflecting target, and a rotating laser projector/receiver that is installed on the moving object and receives the reflected laser beam from one of the reflecting mirrors. and means for detecting the moving distance from the position where the moving object is received to the position receiving the reflected laser beam from the other reflecting mirror, and is configured to calculate the position and direction of the moving object from the detected angle and distance.

According to the present invention, by irradiating a reflective target with a laser beam from a laser rotating projector/receiver provided on a moving object and receiving the reflected laser beam, the traveling direction of the moving object and the reflective target can be determined. The angle made is detected. On the other hand, when a moving object moves, the distance it moves while receiving the reflected laser light from the two reflecting mirrors of the reflective target is detected, and the position and direction of the moving object are automatically measured from this movement distance and the above detection angle. be done.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram showing a two-dimensional position needle and direction measuring device for a moving object, which is an embodiment of the present invention.

In the figure, l is an automatic guided vehicle as a moving object whose position is measured. 2 is a reflective target installed at a two-dimensional arbitrary position (xo, yo) (coordinate values are known) away from the automatic guided vehicle l, and is a reflective target placed in an L-shape as shown in Figure 2. It consists of a reflecting mirror, for example, plane mirrors 3A and 3B, each of which has a reflecting surface of π/2-0 1,
It has an angle of π/2-0-2 and is installed perpendicular to the position measurement plane (XY plane) 4. Therefore, the laser light that is incident on the reflection target 2 at angles of θ1 and θ112 with respect to the X axis is reflected in the direction of incidence. Further, the size of the reflective target 2 used is smaller than the position measurement accuracy.

The automatic transport vehicle 1 is equipped with a rotary laser projector/receiver 5 that irradiates the reflective target 2 with a laser beam 8 and receives a reflected laser beam 15. The configuration of this laser rotary projector/receiver 5 is shown in FIG.

In FIG. 3, 7 is a laser oscillator that emits a laser beam 8, 9 is an L-shaped mount that is driven to rotate at high speed around the optical axis of the laser beam 8 by a motor 10, and a half mirror 11 is 4
It is supported at an angle of 5°. 12 is a collimator lens that converts the laser beam 8 from the laser oscillator 7 into parallel light, and 13 is a cylindrical lens that spreads the laser beam from the collimator lens 12 in one direction.

Reference numeral 14 denotes a photodiode as a light-receiving element fixed to a vertical piece of the pedestal 9, and is adapted to receive reflected laser light 15 when the laser light 8 is irradiated onto the reflective target 2.

Reference numeral 16 denotes an angle detection device attached to the motor 10, which detects the direction of the reflective target 2 from the angle detection signal output from the photodiode 14.

After receiving the reflected light 15 from the one plane mirror 3A, the automatic guided vehicle l receives the reflected light 15 from the other plane mirror 3B.
A wheel tachometer 17 is attached as a means for measuring the travel distance d until the wheel 5 is received.

Next, the operation of the above configuration will be explained.

It is assumed that an automatic guided vehicle 1, which is a position detection object and is equipped with a rotating laser projector/receiver 5, travels as indicated by an arrow O in FIG. In the laser rotary projector/receiver 5, a laser beam 8 from a laser oscillator 7 is converted into parallel light by a collimator lens 12, and then expanded in one direction by a cylindrical lens 13, and a half mirror rotated by a motor 10. 11
As a result, the reflection target 2 is irradiated.

When the automatic guided vehicle l is at the MP position as shown in FIG.
When the automatic guided vehicle 1 reaches position Q, the angle of the laser beam 8 incident on the reflective target 2 becomes θ 1, so the photodiode 14 is detected by the plane mirror 3A. Reflected laser beam 1
5 is received, and an angle detection signal is output. If the angle at this time is measured by the angle detection device 16, the automatic guided vehicle 1
The angle θ between the traveling direction 0 and the direction of the reflective target 2
is found.

It is assumed that the automatic guided vehicle 1 moves straight from position Q to position MR, and no angle detection signal is output during this time.

When the automatic guided vehicle l reaches position WR, the angle of the laser beam 8 incident on the reflection target 2 becomes θI12, so the photodiode 14 receives the laser beam 15 reflected from the plane mirror 3B.
receives light. The distance d from the position MQ to the position R is determined from a wheel rotation meter (not shown) attached to the automatic guided vehicle l.

On the other hand, the following relational expression can be obtained from the geometrical relationship shown in FIG.

) N= X2- d COSφ ・・・・・・(
1) y+= y2- d sinφ...
・・・(2)φ=θ1−θ ・・・・・・
(3)...(4)...(5) By substituting the above detection angle θ and distance d into equations (3) to (5), the automatic guided vehicle at position H can be calculated. Position/direction (
X2. y2. φ) can be obtained.

When using this in a semi-fixed path type, as shown in Figure 4, multiple targets 2 (2+, 22°...
..., 2n) at appropriate intervals along the guide route WO, the automatic guided vehicle 1 can obtain the position/direction (x, y, φ) determined at the first position/direction detection point D1. ), the automatic guided vehicle 1 travels along the guide route WO in a trajectory indicated by W by repeating the same process of freely traveling toward the next position/direction detection point.

At the curve point, it is assumed that the required angle is turned without control at a preset radius. This rotation does not require much precision.

In addition, when using it in a self-supporting type, position P in Figure 1.
Then, by replacing the position and direction measured as described above with the position and direction measured independently, the cumulative error can be eliminated.

In this way, the relatively simple configuration using the reflection target 2 consisting of two plane mirrors 3A and 3B can be used in a semi-fixed path type automatic guided vehicle guidance system, and the cumulative It becomes possible to correct errors. In particular, the reflective target 2 allows a configuration that does not require the use of corner cubes, so material costs are low and manufacturing can be done at low cost, and only one reflective target 2 is required to be attached to a fixed point. Therefore, the position measurement of the fixed point can be simplified, and since it is only necessary to measure one angle for position measurement, angle measurement errors can be reduced and high accuracy can be obtained.

By the way, if the height of the laser rotary projector/receiver 5 of the automatic guided vehicle l is not constant due to the influence of the suspension, etc., and it is difficult to receive the laser beam 15 reflected by the reflective target 2, The same effect can be obtained by using a cylindrical mirror instead and installing it in the same direction as a plane mirror so that the laser beam 15 reflected by the cylindrical surface spreads in the direction perpendicular to the position measurement plane 4.

Effects of the Invention As described above, according to the present invention, a semi-fixed path guidance system can be easily configured using a reflecting target consisting of two reflecting mirrors and a simple configuration used in combination with a laser rotating projector/receiver. In particular, it eliminates the need to use corner cubes, which reduces costs, and reduces the number of corners to be measured, achieving higher measurement accuracy. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a two-dimensional position and direction measuring device for a moving object according to an embodiment of the present invention, FIG. 2 is a diagram showing the arrangement relationship of a reflection target consisting of two reflection mirrors, and FIG. FIG. 4 is a configuration diagram showing a rotating light projector/receiver, and is an explanatory diagram when the present invention is applied to a semi-fixed path type automatic guided vehicle guiding device. 1... Moving object, 2... Reflective target, 3A. 3B...Reflector, 4...Position measurement plane, 5...Laser rotating projector/receiver, 8...Laser light, 15...Reflected laser light, 17...Movement distance detection means, d ...Distance traveled, θ...Angle.

Claims (1)

[Claims] (1) A reflective target composed of two reflective mirrors perpendicular to the position measurement plane of the moving object, and a laser beam irradiated to the reflective target provided on the moving object to detect the position of the moving object from the two reflective mirrors. a rotating laser projector/receiver that receives the reflected laser beam and detects the angle between the traveling direction of the moving object and the reflective target; a means for detecting a moving distance to a position receiving reflected laser light from a reflecting mirror, the moving object being configured to calculate the position and direction of the moving object from the detected angle and distance. 2D position and direction measurement device.