JP2000230971A - Optical position judging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an apparatus consume power considerably small and safe, and prevent the apparatus from applying a load to a battery even when the apparatus is mounted on a motor-driven unmanned transfer vehicle or the like by calculating a coordinate of its own position on the basis of an identification code of each light house and information on the angle of rotation of a reflecting plate of each light house included in signals, and coordinate data or each light house stored in a memory part. SOLUTION: The apparatus consists of a plurality of light houses TX each including a rotary type reflecting plate 2 having a reflecting face symmetric in right and left to a rotary axis and a light-emitting element of a nondirectional radiation pattern and arranged at a predetermined position, and a receiver with a light-receiving part including a photodetector, an operating part and a memory part. The light house TX always transmits the angle of rotation of the reflecting plate 2 while rotating the reflecting plate 2 and a self identification code as signals. The receiver receives signals from the plurality of light houses TX and input to the operating part. The operating part calculates a coordinate of its own position based on the identification code of each light house TX and information on the angle of rotation of the reflecting plate of each light house TX which are included in the signals and coordinate data of each light house TX stored in the memory part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

2. Description of the Related Art In a predetermined area such as a factory, an automatic guided vehicle is generally widely used for transporting a cargo or the like from a specific place to another specific place. The automatic guided vehicle travels unmanned according to a predetermined route. As a guide method for running the route determined by the automatic guided vehicle, a line such as a white line is previously laid on the floor with a tape or paint, and the line is optically identified and traced. Or lay a magnet or magnetic tape on the floor along the route,
A tracing method using a magnetic sensor is generally used.

However, in the above-mentioned method, it is necessary to redraw the line or re-embed the magnets in accordance with the route change, and there is a problem that the route cannot be easily changed.
Therefore, in recent years, a system has been developed in which the vehicle travels along a programmed route by combining self-sustained traveling with a position determination device. As an example of an automatic guided vehicle according to this method, there is an unmanned guided vehicle described in Japanese Patent Application Laid-Open No. Hei 5-341836. In the automatic guided vehicle, a device that determines the position of the vehicle using a laser beam (hereinafter, referred to as a position determination device) is disclosed.

[0003] The system of the position discriminating apparatus described in the above publication is composed of a light emitting / receiving unit mounted on an automatic guided vehicle and a plurality of reflectors installed at predetermined positions in an area where the automatic guided vehicle travels. Be composed. The light emitting / receiving unit includes a turntable that is rotated by a motor, and a laser light source that emits laser light in a horizontal direction on a top surface of the turntable, and a laser light receiver that receives retroreflected light of the laser light. Are mounted substantially parallel to each other. Further, a rotary encoder for detecting the rotation angle of the turntable is provided. The outputs of the laser beam receiver and the rotary encoder are input to a position / azimuth calculator. On the other hand, the reflector is configured by arranging a corner cube mirror having reflecting mirror surfaces arranged at right angles to each other in a cylindrical shape, whereby laser light emitted from the laser light source is returned to the laser receiver. Can be reflected.

The position discriminating device detects the current position according to the procedure described below. The initial position of the automatic guided vehicle and the position coordinates of each reflector are previously input to the position azimuth angle calculation unit. Here, the turntable is rotated, and the output of the rotary encoder when the retroreflected light of the laser light emitted from the laser light source by the reflector is detected by the laser light receiver is read. Then, the position and azimuth angle calculation unit calculates the current position of the automatic guided vehicle by using the principle of triangulation based on the output from the rotary encoder and the previously input position coordinates of each reflector. be able to.

[0005]

In the automatic guided vehicle described above, the device for determining the position of the vehicle is a laser light source and a motor for rotating a turntable on which the laser light source and the laser light receiver are mounted. And is usually
When mounted on an automatic guided vehicle driven by a battery,
There is a problem in that the load on the power supply increases, and it is not desirable to extend the operation time of the automatic guided vehicle as much as possible. Further, if the laser light is irradiated to the eyes for a long time, it may adversely affect the visual acuity, which is not preferable in terms of safety. In addition, even if it does not actually affect the human body, the use of a device that irradiates laser light may put a psychological burden on workers near the automatic guided vehicle. There was a problem that there were many restrictions. further,
The laser device is expensive, and there is also a problem that the total cost of the position determining device increases when a large number of automatic guided vehicles are driven. In addition, the above-described position determination device always needs data of the current position of the own vehicle. If the current position of the own vehicle is lost due to a trouble or the like, return the automatic guided vehicle to the initial position or correct the current position. There was a problem that the position data had to be re-entered.

[0006]

In order to solve the above-mentioned problems, an optical position discriminating apparatus according to the present invention comprises a rotating reflector having a reflecting surface symmetrical with respect to a rotation axis and a non-directional reflector. A plurality of lighthouses provided with a light-emitting element having a radiation pattern and installed at a predetermined position, and a receiver including a light-receiving unit having a light-receiving element, a calculation unit, and a memory unit, the lighthouse is always, The rotation angle of the reflector and the identification code of the reflector are transmitted as a signal while rotating the reflector, and the receiver receives signals from the plurality of lighthouses by the light receiving unit and inputs the signals to the arithmetic unit. And the operation unit includes:
Based on the identification code of each lighthouse included in the signal, the information on the rotation angle of the reflector of each lighthouse, and the coordinate data of each lighthouse stored in the memory unit, calculate the coordinates of its own position. Features.

[0007]

Embodiments of the present invention will be described below in detail. FIG. 1 schematically shows the structure of a lighthouse TX used in the optical position detecting device of the present invention. Reference numeral 1 in the drawing denotes a light emitting element having an omnidirectional radiation pattern in a horizontal plane. In this embodiment, an infrared light emitting diode that emits infrared light is used. The infrared light emitting diode 1 is connected to a control circuit 6 to be described later, and transmits an identification code of the lighthouse TX and information of a rotation angle of the reflector 2 to be described later as a pulse signal by blinking. In the vicinity of the infrared light emitting diode 1, a reflector 2 that rotates about the infrared light emitting diode 1 is provided. The reflection plate 2 is fixed on an annular rotary table R rotatably arranged around the infrared light emitting diode 1. The reflecting plate 2 has a curved reflecting surface which is symmetrical with respect to the rotation axis, reflects light emitted from the infrared light emitting diode 1, and gives the emitted light directivity. Play a role. Further, on the turntable R, a shielding plate 3 is provided on the opposite side of the reflecting plate 2 with the infrared light emitting diode 1 interposed therebetween. The shielding plate 3 shields the light emitted from the infrared light emitting diode 1 other than the light reflected by the reflecting plate 2. The rotary table R is driven to rotate by the motor 4 via the gear train A. The rotary table R is connected to a rotary shaft 5a of the rotary encoder 5 via a gear train B so as to transmit a rotational force. The rotary encoder 5 transmits a signal in accordance with the rotation of the rotary table R, that is, the reflection plate 2. Output. As the rotary encoder 5, both an incremental rotary encoder that outputs a pulse signal in accordance with the rotation of the rotary shaft 5a and an absolute rotary encoder that outputs the absolute value of the rotation angle of the rotary shaft 5a as a code signal can be used. it can. An output from the rotary encoder 5 is input to a control circuit 6, where a position information signal to which a lighthouse identification code and the like are added is generated. The position information signal is transmitted to the control circuit 6
Is transmitted as a pulse signal by the blinking of the infrared light emitting diode 1 connected to.

The case where an incremental type rotary encoder is used as the rotary encoder 5 will be described. The incremental type rotary encoder outputs a signal of one pulse every time the rotating shaft rotates by a predetermined angle. For example, in the case of outputting a signal of 1800 pulses in one rotation, a signal of one pulse is output every time the rotation axis rotates 0.2 degrees. Further, since the rotary table R and the rotary shaft 5a are connected via the gear train B, for example, if the rotation of the rotary table R is increased by 10 times by the gear train B and transmitted to the rotary shaft 5a, Since a signal of one pulse is output every time R rotates 0.02 degrees, the resolution of the rotation angle of the turntable R can be improved. In addition, an origin detection device that outputs an origin pulse signal each time the rotary table R makes one rotation is separately configured to detect the origin position of the rotary table R. The pulse signal from the rotary encoder 5 and the origin pulse signal from the origin detection device are input to the control circuit 6, respectively. In the control circuit, the rotation angle from the origin position of the turntable R, that is, the reflection plate 2, is calculated by counting the pulse signals after the input of the origin pulse signal. Explaining with the above example, when the count value of the pulse signal from the origin pulse signal is 2000 pulses, 0.02 (degrees / pulse) × 2
000 (pulse) = 40 (degrees), which means that the reflection plate 2 is rotated by 40 degrees from the origin position. The angle information thus calculated is converted into a binary code signal, and the code signal is added with a lighthouse identification code signal and a start signal indicating the start of the signal to obtain a position information signal. As another method, the count value of the pulse signal from the origin pulse signal may be directly converted into a binary code signal, and an identification code signal and a start signal may be added to the code signal to generate a position information signal. In this case, the rotation angle of the reflector 2 may be calculated from the count value on the receiving side. The generation and transmission of the position information signal are performed for each pulse. That is, the lighthouse keeps transmitting the rotation angle from the origin position of the reflector and its own identification code while constantly rotating the reflector.

Next, a case where an absolute type rotary encoder is used as the rotary encoder 5 will be described. The absolute type rotary encoder outputs the absolute value of the rotation angle of the rotation shaft as a code signal. Therefore, the gear train B has a speed ratio of 1, and is connected such that the rotation of the rotary table R and the rotation of the rotary shaft 5a correspond one-to-one. The code signal is input to the control circuit 6,
In the control circuit, an identification code signal and a start signal are added to the code signal to obtain a position information signal. The generation and transmission of the position information signal are performed each time the code signal from the rotary encoder 5 changes, and while the reflector is constantly rotated, the rotation angle of the reflector from the origin position and the self identification code are continuously transmitted.

FIG. 2 schematically shows a configuration of a receiver used in the optical position detecting device of the present invention. The receiver RX includes a light receiving unit 7, a calculating unit 8, and a memory unit 9. The position information signal from each lighthouse TX received by the light receiving unit 7 and the coordinates of each lighthouse TX stored in the memory unit 9. The data of (installation position) is input to the calculation unit 8, and the current position of the receiver RX is calculated by a method described later using the position information signal and the coordinate data. As shown in FIG. 2, the light receiving unit 7 includes a substantially conical reflecting mirror 701 installed with its central axis set in a vertical direction, and the reflecting mirror 7.
It is composed of one light receiving element 702 located on the vertex side of 01 and on an extension of the central axis, and a transparent cylindrical member 703 supporting the reflection mirror 701. With this configuration,
Since the reflection mirror 701 reflects the signal light from all directions in the horizontal direction toward the light receiving element 702, one light receiving element can receive the signal light from all directions in the horizontal direction. Of course, like the light receiving section 7 'shown in FIG. 3, a plurality of light receiving elements 702, 702,.
May be arranged in different directions to receive signal light from all directions in the horizontal direction.

Next, a method of determining the position of the optical position detecting device according to the present invention will be described. Basically, this apparatus is installed at a predetermined position with the origin of the reflector facing the same direction, and a plurality of lighthouses TX having different identification codes.
, TX2, TX3,... And one receiver RX, and calculates the position of the receiver RX based on position information signals from two or more lighthouses. Hereinafter, a case where two lighthouses are used will be described for the sake of simplicity. As shown in FIG. 4, the lighthouses TX1 and TX2 each have a predetermined coordinate (x ₁ ) in the xy plane with the origin position of the reflection plate facing the negative direction of the y-axis (the direction indicated by the dotted line in the drawing). , Y ₁ ), (x
₂ , y ₂ ). The coordinates of each lighthouse TX1, TX2 are stored in the memory unit 9 of the receiver RX in association with the identification code of each lighthouse. Now, the receiver when the receiver RX is referred to as being any coordinates (x, y), the receiver RX is, the position information signal from the lighthouse TX1 when reflector rotation angle theta ₁ lighthouse TX1 (signal light) ( receiving), and will receive a location information signal from the lighthouse TX2 when _two reflector rotation angle of the lighthouse TX2 is theta (signal light) (light receiving). Actually, as shown in FIG. 5, the signal light provided with directivity by the reflector does not have complete beam directivity, but has directivity having _a certain angle range θa. Here, since the reflector of the lighthouse TX is bilaterally symmetrical with respect to its rotation axis, when the receiver RX starts receiving signal light (FIG. 5A), the rotation angle of the reflector is 0 ', and the receiver RX Is the rotation angle θ of the reflector just before the signal light is no longer received (FIG. 5b), the rotation angle θ of the reflector when the optical axis A of the reflector faces the receiver RX from the following equation. Can be requested.

[0012]

[Formula 1]

FIG. 6 is a graph showing the relationship between the rotation angle of the reflector and the intensity of the signal light reaching the receiver RX.
When the distance between the lighthouse TX and the receiver RX is short, FIG.
When the distance between the lighthouse TX and the receiver RX is long, the pattern becomes as shown in FIG. 6B. Note that S is the lower limit of the light intensity that can be detected by the light receiving element of the receiver RX. As can be seen from the graph, since the reflecting surface of the reflecting plate is symmetrical with respect to the rotation axis, the distribution of the intensity of the signal light reaching the receiver RX is independent of the distance between the lighthouse TX and the receiver RX. It is always kept symmetrical about the optical axis of the reflector (that is, the angle θ in FIG. 6). Accordingly, the distance between the lighthouse TX and the receiver RX, that is, regardless of the intensity of the signal light reaching the receiver RX, the rotation angle θ ′ of the reflector when the receiver RX starts receiving the signal light, From the rotation angle θ ″ of the reflector immediately before the receiver RX stops receiving the signal light, the optical axis of the reflector is changed to the receiver RX.
It can be understood that the rotation angle θ of the reflector when facing in the direction of is accurately obtained.

When signal lights from a plurality of lighthouses TX, TX,... Simultaneously enter the receiver RX, a plurality of position information signals are superimposed, and it is possible to correctly receive each position information signal. Therefore, it is desirable to rotate the reflectors of each lighthouse in a synchronized manner so that signal lights from a plurality of lighthouses do not simultaneously enter the receiver RX. Since the signal light from the lighthouse TX has _a certain angle range θa as described above, even if the rotation of the reflector of each lighthouse is synchronized, two light sources may theoretically be provided depending on the position of the receiver RX. It is conceivable that the signal light from the above lighthouse enters the receiver RX. However, the position where the signal light from two or more lighthouses is incident is a position far away from the lighthouse, so the signal light is diffused at such a position, and the light receiving element of the receiver RX is Since the light intensity becomes smaller than the lower limit of the detectable light intensity, the above-described problem does not actually occur.

A line connecting the lighthouse TX1 and the receiver RX, and
Lines connecting the lighthouse TX2 and the receiver RX are represented by the following equations, respectively.

[0016]

[Formula 2]

[Equation 3]

The coordinates (x, y) of the receiver RX are

And a straight line represented by

Since it is the intersection with the straight line represented by the equation (3), by solving the simultaneous linear equations of the above two equations, θ ₁ , θ
₂ , x ₁ , x ₂ , y ₁ , y ₂ . That is, the respective position information signals (the rotation angle of the reflection plate + identification code) transmitted from each of the lighthouses TX1 and TX2 and each of the lighthouses TX1 and TX2 obtained by referring to the identification code in the memory unit 9 of the receiver RX. From the coordinates of the receiver RX.

As described above, the optical position discriminating apparatus according to the present invention determines the current position of the receiver from the position information signal transmitted from the lighthouse and the coordinate data of each lighthouse stored in the memory unit of the receiver. Since the system is a calculation system, there are the following merits. That is,

2. Description of the Related Art In a position discriminating apparatus using a laser beam and a reflector described in the section, since no information is contained in the retroreflected light from the reflector, only the retroreflected light is received. In this case, it is not possible to specify at which position in the area the reflector is located. In order to specify the reflector, the approximate position of the vehicle (light emitting / receiving unit) must be known in advance. Need to be. Therefore, in the above-described conventional device, it is necessary to perform an initial setting such as starting from a determined initial position or inputting data of the current position. If the current position is lost, the correct current position may not be able to be determined even after receiving the retroreflected light. Therefore, in order to return the position discriminating device, it is necessary to return to the determined initial position or to input data of the current position again. On the other hand, in the position determination device according to the present invention, even if the current position is lost due to a trouble or the like, the current position can be determined only by receiving the position information signal from the lighthouse again, and the position determination device is returned. There is no need for the above-mentioned troubles, and it is very convenient.

Furthermore, in addition to the above-mentioned advantages, the receiver of the optical position discriminating apparatus according to the present invention has no moving parts and consumes little power, so that it takes the form of a portable terminal as shown in FIG. Is also easy. In the figure, reference numeral 7 denotes a light receiving unit, reference numeral 10 denotes a housing containing a computing unit, a memory unit, a battery and the like, and reference numeral 11 denotes a display for displaying a current position. For example, if a necessary number of lighthouses are installed in a predetermined position in a department store or event venue in advance, the visitor can easily know his / her current position by lending the portable terminal to the visitor. Visitors only need to turn on the terminal and receive the location information signal from the lighthouse when they want to know their current location. Suitable for.

[0020]

As described above, in the optical position discriminating apparatus according to the present invention, as the lighthouse, the light emitting element having the omnidirectional radiation pattern and the rotating light having the reflecting surface symmetrical with respect to the rotation axis are used. Combined with a reflective plate,
By transmitting the rotation angle of the reflector and its own identification code as a signal while rotating the reflector,
An expensive system such as a laser is not required, and a system capable of accurately determining the position can be constructed using an inexpensive light source such as an infrared light emitting diode. In addition, since a laser or the like is not used, there is no adverse effect on the human body (eyes), and there is no psychological burden on workers near the lighthouse. On the other hand, the receiver is composed of only a light receiving section having a light receiving element, an arithmetic section and a memory section, so that the power consumption is extremely small, and a load is imposed on the battery even when the receiver is mounted on an electric automatic guided vehicle or the like. Without
The operating time can be made as long as possible. Further, since the receiver can be configured at a very low cost, for example, when traveling a large number of automatic guided vehicles in the same area,
The total cost can be reduced as compared with the conventional position determination device. Furthermore, the optical position discriminating apparatus according to the present invention has a mechanism for calculating the coordinates of the current position based on the position information signals transmitted from the plurality of lighthouses and the coordinate data of each lighthouse stored in the memory unit. Therefore, even if the current position is lost due to a trouble or the like, the current position can be immediately determined by receiving the position information signal from the lighthouse again. Therefore, there is no restriction on the use such as starting from the determined initial position or inputting the data of the current position as the initial setting, and the usability is very good. In addition, by utilizing the above-listed advantages, it is possible to realize a portable position determining device for rental at an event venue or the like, which is difficult with a conventional position determining device.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a structure of a lighthouse used in an optical position detecting device of the present invention.

FIG. 2 is a schematic diagram showing a configuration of a receiver used in the optical position detecting device of the present invention.

FIG. 3 is a perspective view showing another embodiment of the light receiving section of the receiver used in the optical position detecting device of the present invention.

FIG. 4 is an explanatory diagram illustrating a method of position determination.

FIG. 5 is an explanatory diagram illustrating a method for detecting a rotation angle of a reflector of a lighthouse.

FIG. 6 is an explanatory diagram illustrating a method of detecting a rotation angle of a reflector of a lighthouse.

FIG. 7 is an external view of a portable terminal.

[Explanation of symbols]

 TX lighthouse RX receiver 1 Infrared light emitting diode 2 Reflector 3 Shield 4 Motor 5 Rotary encoder 6 Control circuit 7, 7 'Light receiver 701 Reflector mirror 702 Light receiver 703 Cylindrical member 8 Operation unit 9 Memory unit 10 Housing 11 Display A, B Gear train R Rotary table

Claims (5)

[Claims] 1. A plurality of lighthouses, comprising: a rotating reflector having a reflecting surface symmetrical with respect to a rotation axis; and a light emitting element having an omnidirectional radiation pattern; The lighthouse constantly transmits the rotation angle of the reflector and its own identification code as a signal while rotating the reflector, the receiver comprising a light receiving unit having an element, an arithmetic unit, and a memory unit. The receiver receives signals from the plurality of lighthouses by the light receiving unit and inputs the signals to the arithmetic unit. The arithmetic unit includes an identification code of each lighthouse included in the signal and a reflector of each lighthouse. An optical position discriminating device which calculates coordinates of its own position based on the information on the rotation angle of the light source and the coordinate data of each lighthouse stored in the memory unit. 2. The optical position determining device according to claim 1, wherein said light emitting element is an infrared light emitting diode. 3. The light plate according to claim 1, wherein the reflectors of the lighthouses rotate in synchronization with each other so as to face the same direction, so that signals from two or more lighthouses do not enter the receiver at the same time. The optical position discriminating apparatus according to claim 1. 4. A light-receiving unit comprising: a conical reflection mirror provided with its central axis set in a vertical direction; and one light-receiving unit located on the vertex side of the conical reflection mirror and on an extension of the central axis. The optical position discriminating apparatus according to claim 1, comprising an element. 5. The optical system according to claim 1, wherein the light receiving section is constituted by a plurality of light receiving elements installed in different directions from each other. Position determination device.