JP3340606B2 - Guidance method and guidance system for mobile robot - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a system for running an unmanned mobile robot on a designated route by relying on landmarks (guide signs) installed on the traveling route.

[0002]

2. Description of the Related Art As a method for guiding a mobile robot, various landmarks (guidance signs) are installed at key points in a route, and the robot travels on a designated route depending on the signs. is there. The present invention provides a method for constructing a sign in such a method for guiding a mobile robot, a method for detecting and recognizing the sign, and a method for accurately measuring and correcting the position and direction of the robot using the sign.

There are two methods of navigation for an autonomous mobile robot: guidance by landmarks and dead reckoning (route navigation). The latter has a major drawback that it gradually moves away from a predetermined route due to accumulation of errors. . The following must be considered as the conditions of the landmark object. (1) Easy to distinguish from surrounding objects (2) Simple structure, small size and light weight (3) Able to show accurate position to robot (4) Data is not lost due to dirt or damage

The conventional guidance method using landmarks has the following problems. (1) In order to install a magnetic tape or light reflective tape on the floor, it is necessary to stick the tape on the entire route, and the tape may be stepped on by humans or the robot itself, deformed or damaged, or lose magnetism. (2) A system equipped with a CCD camera has complicated image processing and may possibly misidentify a sign. (3) Since a plurality of signs are required to measure the position of the robot, installation is complicated. Is

[0005] Japanese Patent Publication No. 5-70844, "Reading device for light reflection tape for guiding automatic guided vehicles and detecting information" includes:
Although an unmanned guidance system using a light reflecting tape and an optical fiber cable is disclosed, there is a disadvantage that the light reflecting tape laid on the floor is easily stained and easily damaged. In Japanese Patent Application Laid-Open No. 4-346107, "light guiding line detection device", even if there is a metal piece on the floor, or if the light reflecting tape installed on the floor is dirty or damaged,
Although the binarized signal is arithmetically processed to determine the position of the guide line, signal noise is generated due to disturbance such as unevenness of the floor surface, so that there is a disadvantage that reliability is lacking. JP-A-4-42014 "Method and apparatus for detecting the self-position of a moving object"
Describes a method for guiding a moving body using laser light by the present inventors.

[0006]

SUMMARY OF THE INVENTION It is a main object of the present invention to provide a guidance method for facilitating the installation of a sign for guiding a mobile robot, and also for identifying a marker and measuring a relative position between the marker and the mobile robot. It is to provide a device. It is another object of the present invention to minimize the number of guidance signs, prevent malfunctions, and achieve an accurate guidance method.

[0007]

According to a first aspect of the present invention, there is provided, in accordance with the first aspect, two or more types of light reflection devices having different light reflection characteristics in a path along a traveling direction of a mobile robot. A marker in which objects are arranged in a predetermined order and at a predetermined interval is installed, a laser beam is radiated from the laser source mounted on the mobile robot to the marker, and the marker is reflected by the reflected light receiving device mounted on the mobile robot. And the light on the marker is detected by the reflected light receiving device.
Detects the location of the marker by detecting the arrangement of reflective objects,
A plurality of grounds on the marker by the reflected light receiving device;
Measure the angle between the point and the reference point on the mobile robot, and
Calculate the position and orientation of the mobile robot with respect to the
Marker address / position of mobile robot / mobile robot
A method for guiding a mobile robot is provided, wherein the mobile robot is guided based on three types of information on the direction of the mobile robot.

[0008] This guidance method is also used for traveling a long distance.
In this case, a method of guiding while detecting multiple markers in order
Steps can be included. The present invention provides, as a second aspect thereof, a guidance system for performing the above-described guidance method.

As a specific configuration, the present invention uses the following method. (1) Two or more types of objects having different light reflection characteristics are arranged in an appropriate order, and a unique code (or number) is given to each sign by a pattern based on a combination of arrangement methods. In addition, at least three or more boundaries where objects having different light reflection characteristics are arranged are provided, and these boundaries are used as reference points. However, it is assumed that the size of the object constituting the marker is known, and the distance between the reference points is known.

(2) The sign detecting device mounted on the robot irradiates the object constituting the sign with appropriate light and detects the difference in the reflection characteristic of the reflected light, thereby detecting the reflection characteristic of the object constituting the sign. The differences are identified, thereby identifying the pattern of the sign, that is, the sign unique to the sign. At the same time, the boundary where objects having different light reflection characteristics are arranged, that is, the above-mentioned reference point is detected from the change in the reflection characteristics of the reflected light. However, the angle of the light emitting direction from the reference direction of the robot can be measured.

(3) The robot knows its own position on the map by checking the sign of the sign obtained as described above with the sign of the sign on the map previously given to the robot. Do). However, this alone indicates that the robot is near the sign, but the exact position and orientation of the robot are unknown. However, since the angle of the light emission direction from the reference direction of the robot can be measured, the angle from the reference direction of the robot when the above-mentioned reference point is viewed from the robot can be determined. Can be used to determine the position and orientation of the robot with respect to the sign based on the principle of triangulation. Thereby, the robot can accurately perform its own positioning or correction.

As a preferred example of the sign, two types of polarizing films whose polarization directions are different, for example, vertical and horizontal, are arranged in an appropriate order on a light-reflecting object (for example, a reflecting tape). A unique code (or number) is given to each marker by a pattern based on the combination of Here, when non-polarized light enters the polarizing film, the reflected light reflected by the reflecting object and transmitted again through the polarizing film is polarized light corresponding to the polarization direction of the polarizing film.

The sign detection device mounted on the robot is composed of a part for scanning an appropriate non-polarized light and a part for detecting a difference in the polarization direction of reflected light from the sign. When a semiconductor laser is used as a light source, since the semiconductor laser is linearly polarized, a quarter-wave plate is placed immediately after the light source and circular polarization is used, so that it can be considered practically non-polarization.

The reflected light detecting section has two light receiving sections, and at the head of each light receiving section, the same two kinds of polarizing films as those used for the signs are respectively installed. Thereby, each light receiving section responds only to the specific polarized light. When the difference signal of the output of each light receiving unit is taken, since the reflected light from the object other than the sign is unpolarized, the output of both light receiving units is small and equal, so the difference signal becomes zero, and the reflected light from the sign is the polarization film. + Or-output depending on the polarization direction. As a result, the presence of the marker and the pattern of the marker, that is, the sign, can be detected, and the change point of the difference signal from + to-and from-to + is detected as the reference point.

In the present invention, it is not necessary to install landmarks continuously, but only at corners or reference points. Therefore, the number of landmarks is minimized, malfunction is prevented, and an accurate guidance method is provided. Achieved. Hereinafter, preferred embodiments according to the present invention will be described with reference to the accompanying drawings.

[0016]

FIG. 1 shows an example of a moving path of a mobile robot 10. As shown in FIG. Mobile robot 1 along such a route
When navigating 0, the dead reckoning operation alone by the robot's internal sensor may cause the robot to go off course due to accumulation of position detection errors during traveling. Therefore, markers (guidance signs) 20 and 21 are provided at points that require high-precision self-position detection and positioning, such as around corners, elevator doors, and work places 14, and the robot itself detects the map by detecting them. Be able to recognize where you are above.

Further, by providing the marker itself with an optical feature, the marker is detected and identified at the same time, and the angle between a plurality of points on the marker and a reference point on the mobile robot is measured. It is possible to know the exact self-position and direction of the mobile robot, and to construct a more accurate robot guidance system.

FIG. 2 shows a specific example of the marker 20. For example, a reflective tape 24 that reflects light in the incident direction is applied to a thin aluminum plate 22 having a width W of 200 mm and a height H of 40 mm by using an adhesive or the like. , And two types of polarizing films 31 to 38, which are vertically and horizontally, in which the transparent polarization directions are orthogonal to each other, are arranged and attached in parallel. The polarizing film itself may be of one type, and two types are formed, one being cut vertically and one being cut horizontally. The overall thickness of the marker is about 2 mm, and it is thin and light, so that even if it is installed on a wall, it does not hinder the progress of humans and does not need to be connected to a power supply. Since no additional equipment such as a light source or cord is required, it can be easily mounted on a wall or the like.

Since the polarizing films 31 to 38 are transparent, if the address information is written on the reflective tape 24 by numbers, the information of the marker 20 can be read by a human, and it becomes a sign that can be simultaneously identified by the human and the robot. If "emergency exit" or the like is described on the reflective tape 24, it can also serve as a guide sign, which is convenient.

FIG. 3 shows a mobile robot 40 and a marker reading device mounted thereon. The base portion 42 of the mobile robot 40 houses a power source and a running motor 43 in the same manner as a conventional autonomous mobile robot,
The vehicle drives the wheels 45 and 46 and runs while being steered by the front wheels 47.

The marker reading device includes a laser light source 5
0, a scanning unit 55, and a reflected light receiving device 60. Light of a 20 mW semiconductor laser is circularly polarized as a collimating light source and used as apparently unpolarized light. The light 51 emitted from the semiconductor laser is scanned on a horizontal plane by a reflection mirror 58 attached at a 45-degree inclination on a turntable 57 driven by a motor 56, and is rotated toward a marker 70 on the wall surface 12. Is done. The rotation speed may be, for example, about 10 rps.

A reflected light receiving device 60 is mounted on the same turntable 57, and its rotation angle is measured by an optical rotary encoder 59 mounted coaxially. In the light receiving device 60, two photodiodes 63 and 64 attached to the rear side of two polarizing films 61 and 62 having orthogonal polarization directions are used. The light receiving device 60 can simultaneously measure the polarization direction and the intensity of the light reflected from the marker 70 or the like.

A personal computer 80 is further mounted on the mobile robot 40. The personal computer 80 is preliminarily input with map information of a moving route, and based on information from a marker reading device, the current state of the mobile robot is determined. The position is calculated, and a command to move in the next direction is issued to a traveling device such as the traveling motor 43.

The mobile robot 40 according to the present invention is configured as described above, and the non-polarized light 51 emitted from the laser source 50 is scanned horizontally on the marker 70 in the Q direction. The reflected light R is reflected light polarized in each direction by the polarizing films 71 to 74 (FIG. 4) arranged on the marker 70 and the reflecting tape.

As shown in FIG. 4, assuming that two types of polarized light directions (vertical and horizontal directions) are P-polarized light and S-polarized light, the reflected light R from the marker 70 shown in FIG.
Polarized light-P polarized light-S polarized light. The reflected light is P-polarized light, S
The photodiodes 63 and 64 on the light receiving device 60 on which the polarization films 61 and 62 for polarization are attached are photoelectrically converted and detected.

At this time, objects other than the marker ((wall surface 1
2 or the reflected light from the reflecting object 76) is non-polarized light, so that the output of the photodiode (P element) provided with the P-polarized polarizing film and the output of the photodiode (S element) provided with the S-polarized polarizing film are almost the same. It shows the same value and there is almost no difference in output. On the other hand, when light polarized in either direction is reflected, only the output of either the P element or the S element increases, and the output difference (P−
Taking S) indicates a plus or minus value, and it is possible to determine whether the light reflection location is a location where a P-polarized film is applied or a location where an S-polarized film is applied. At the same time,
It can also be easily recognized that the place where the value of (PS) shows a certain threshold M or more is the marker existence area.

In this way, when polarizing films are arranged in various patterns on the marker and each pattern has address information on the map, the mobile robot that detects the information can determine its own position on the map. You can know. In addition, since the method detects P-polarized light and S-polarized light from the output difference between the two photodiodes, the detection device has a high S / N ratio.

Further, since the dimensions of the polarizing film disposed on the marker are known in advance, the boundaries between the respective patterns of the polarizing film are detected, and the angle between the boundaries as viewed from the robot is determined by the rotation axis of the marker reading device. When the measurement is performed by the rotary encoder 59 attached to the robot, the position and orientation of the robot with respect to the marker can be calculated based on the principle of triangulation.

That is, in the XY coordinate system as shown in FIG. 5, the boundary of the polarizing film of the marker 70 is defined as A, B, C.
(For example, assuming that the boundary between the polarizing films 31 and 32 in FIG. 2 is A, the boundary between 34 and 35 is C, and the boundary between 37 and 38 is B), their coordinates are known, and the position T (X, Y) and the direction θ _r can be obtained by the following equations. _{x r = x a (1 +} Kcotβ) / (1 + K 2) y r = Kx r θ r = tan -1 (y r / x r) - θ c _{However, α = θ c - θ b} β = θ a - θ c _{K = (x a - x b} ) / (- x b cotα-x a c
otβ) However, when (−x _b cot α−x _a cot β) = 0, x _r = x _a / tan α y _r = 0.

Here, θ _a , θ _b , and θ _c are the angles of boundaries A, B, and C desired from the reference point of the robot. From this figure, it can be seen that the self-position measurement is possible if there are at least three boundaries, so that the robot self-position measurement is possible if there are at least two polarizing films per marker.

FIG. 6 is a block diagram showing a mobile robot guidance system according to the present invention. Laser light is emitted from the semiconductor laser by the laser oscillator, is rotationally scanned by a rotating mirror 58 attached to a DC motor 56 driven by a DC motor driver, and irradiates the polarization marker 70 with the laser light. Light reflected from the marker 70 is polarized light films 61 and 62 of P-polarized light and S-polarized light.
And photoelectrically converted by the photodiodes 63 and 64. The converted electric signal is selected and amplified by a tuner amplifier, binarized, and only a value exceeding a threshold value is extracted through a binarization filter. Sent to computer 80.

On the other hand, the rotary encoder 59 detects the irradiation angle of the laser beam from the rotation angle of the DC motor 56,
Sending a signal to the A / D converter via the clock generator,
Further, a signal is sent to the personal computer 80. The personal computer 80 calculates the current position of the mobile robot from the map information of the moving route input in advance, and issues a command to a traveling device such as the traveling motor 43 to move the mobile robot in the next direction.

As described above, when a marker of a known size is arranged at a known location on the movement route, the self-position on the map is known from the marker arrangement pattern, and the corner formed by the pattern is detected. Since the user can know the coordinates and the azimuth which are the self-positions with respect to, the mobile robot can be guided accurately.

The method for guiding a mobile robot according to the present invention comprises:
It can be widely applied to an assembly line robot at an FMS factory, an automobile navigation system in a specific section, a postman robot, a security patrol robot, an amusement park attraction vehicle, a garbage collection robot in a building, and the like.

[0035]

As described in detail above, according to the present invention, (1) a robot guidance system using a light reflective marker can be used to determine the accuracy of the robot's own position and azimuth at any position where the marker can be detected. High measurement is possible (2) Measurement error is small because high S / N ratio can be detected. (3) Markers are small and lightweight and do not require a power source, so they are easy to install and move. (4) Multiple markers are used. It can be installed at a low cost because it is separated and installed. (5) By adding characters to the marker, the information can be visually checked and it can be used as a guide plate. Some of the technical effects are extremely remarkable.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating a traveling route of a mobile robot according to the present invention.

FIG. 2 is a front view of a polarization marker that reflects light.

FIG. 3 is a perspective view showing reflection of a laser beam and a marker from a mobile robot.

FIG. 4 is a waveform chart illustrating a method of measuring the reflection intensity from a marker.

FIG. 5 is a coordinate plan view illustrating a method of calculating a position of a mobile robot from a marker.

FIG. 6 is a block diagram illustrating a connection method of components and a signal flow.

[Explanation of symbols]

 10, 40 Mobile robot 12 Wall surface 20, 21, 70 Marker 22 Aluminum plate 24 Reflective tape 31-38 Polarized film 43 Running motor 50 Laser source 56 Motor 57 Turntable 58 Rotating mirror 59 Encoder 61, 62 Polarized film 63, 64 Photo Diode 71-74 Polarized film 80 PC

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kazuhiro Mima 1798 Oshidate, Inagi-shi, Tokyo (72) Inventor Koetsu Tanaka 2-4-1 Yotsuya, Shinjuku-ku, Tokyo Inside Shinryo Corporation (56) Reference Document JP-A-61-169908 (JP, A) JP-A-2-80991 (JP, A) JP-A-3-171304 (JP, A) JP-A-58-129609 (JP, A)

Claims (4)

(57) [Claims] 1. A marker in which two or more types of light reflecting objects having different light reflection characteristics are arranged in a predetermined order and at a predetermined interval along a path along a traveling direction of a mobile robot, and mounted on the mobile robot. Laser light is emitted from the laser source to the marker, the marker is detected by a reflected light receiving device mounted on the mobile robot, and the reflected light object on the marker is detected by the reflected light receiving device.
By detecting the arrangement, the address of the marker is identified, and a plurality of locations on the marker are detected by the reflected light receiving device.
The angle between the point and the reference point on the mobile robot is measured, the position and orientation of the mobile robot with respect to the marker are calculated , and the address of the marker, the position of the mobile robot, and the mobile robot are calculated.
A method for guiding a mobile robot, wherein the method guides the mobile robot based on three types of information on the direction of the mobile robot. 2. When traveling a long distance, a plurality of
Including a step of inducing markers while detecting them sequentially
The guidance method according to claim 1. 3. A system for guiding a mobile robot to a sign placed in a path along the traveling direction of the mobile robot, wherein the two or more types of lights are installed in the path and have different light reflection characteristics. A marker in which reflective objects are arranged in a predetermined order and at a predetermined interval; a laser scanning means for scanning while rotating the laser light from a mobile robot; and detecting light reflected by the laser light hitting the marker And a reflected light receiving device mounted on the mobile robot, wherein the reflected light receiving device is a rotary encoder and a computer.
The reflected light receiving device is arranged on a marker.
Can be detected to identify the address of the marker, and the reflected light receiving device can detect a plurality of locations on the marker.
By measuring the angle between the point and the reference point on the mobile robot,
Guidance system of the mobile robot, which is a possible exit compute the position and orientation of a mobile robot for manufacturers. 4. A character that can be viewed by a human is displayed on the marker, and information on the marker is readable by a mobile robot and character information is obtained by a human.
4. The guidance system according to claim 3, wherein the guidance system is capable of performing the following.