JP2013084192A - Self-position determination device for traveling object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the self-position determination device for a traveling object for easily matching an angle (azimuth) in the traveling direction of a traveling object at a start point of a position determination arithmetic operation with an angle (azimuth) set in an area where the traveling object actually travels with reducing an error.SOLUTION: Photoelectric sensors 12 and 13 are attached to both side faces of a traveling object 10 at a right angle to the traveling direction of the traveling object 10, and reflection boards 14 and 15 for reflecting the rays of light of the photoelectric sensors 12 and 13 are arranged at both sides of a storehouse entrance 1 of a traveling area so as to be faced to the optical axes of the photoelectric sensors 12 and 13. An operation time difference between the photoelectric sensors 12 and 13 when the traveling object 10 passes through the storehouse entrance 1 is used to calculate the angle of the traveling object in passage.

Description

  The present invention relates to a self-position determination device for a moving body based on a position detection method (hereinafter referred to as “odometry method”) using an angle sensor (gyro) and a rotation sensor (encoder).

2. Description of the Related Art Conventionally, an apparatus for determining the self-position of a moving body is used, for example, when managing the position of an item in a storage warehouse that is carried in and out by a transport vehicle or the like within a plane coordinate.
There are several methods for determining the self-position of a mobile body (for example, a transport vehicle that travels in a storage warehouse) that freely travels with a vehicle, a self-propelled robot, or the like, each having its own characteristics.

First, the GPS system is well known, but it cannot be used in a building surrounded by underground or reinforced concrete because radio waves do not reach it.
Also, a wireless LAN system (for example, see Non-Patent Document 1) has been proposed, but the position determination accuracy is as low as 1 m to 3 m, and for example, in an environment such as a low temperature warehouse, multiple antennas are installed in the warehouse. Difficult and not feasible.

  On the other hand, using the signal from the angular velocity sensor and the signal from the encoder that detects the rotation of the wheel of the moving body, the XY coordinate change amount obtained by calculating the angle and moving distance of the moving body is integrated, An odometry method for obtaining the self-position has also been proposed (see, for example, Non-Patent Document 2).

  The method using the odometry method solves the problems of the GPS method and the wireless LAN method, and can be supplemented in a tunnel in the GPS method and can be used in a low-temperature warehouse. In practical use.

  However, in the self-position determination apparatus based on the odometry method, there is a basic problem of cumulative error, and it is necessary to determine the start point of the self-position determination calculation of the moving body as an important use condition.

  For example, in a warehouse storage management system that recognizes the storage location of stored items in a warehouse using the self-location data of the transport vehicle, the self-installed in the transport vehicle is set as the start point of the self-position determination calculation. It is necessary to input the starting point coordinates of the transport vehicle corresponding to the plane coordinates of the warehouse and the starting point angle (azimuth) of the transport vehicle corresponding to the predetermined direction in the plane coordinates to the position determination device.

At this time, as a method of initially setting the starting point coordinates and the starting point angle (azimuth) at the start position of the transport vehicle (moving body), for example, the transport vehicle is temporarily stopped in front of the entrance door of the warehouse, and the driver It is conceivable to perform a reset operation with a switch of the arithmetic processing unit after setting the direction so as to go straight at right angles to the entrance door surface.
Alternatively, it is conceivable that a photoelectric sensor is provided at a position where the initial setting is performed, the photoelectric sensor signal is worked on the arithmetic processing unit, and the initial setting is automatically performed at a timing when the signal passes through the entrance door of the warehouse.

In any of the above initial setting methods, since there is no means for easily measuring the angle of the transport vehicle (moving body) on the mobile body side, the transport vehicle is placed at the warehouse entrance section in the plane coordinates set at right angles to the warehouse entrance. It is necessary to install without having an angle with respect to the approach direction coordinates and to forcibly set the angle to zero.
Or, it is possible to use a geomagnetic sensor to detect the self-orientation and convert it to the angle of the warehouse plane. However, it is difficult to obtain the angle with an accuracy of 2 ° or less, and in a reinforced concrete structure Since the detection accuracy decreases, it can be said that the geomagnetic sensor itself is not actually applicable.

Even if the driver installs the moving body in a straight direction, the driver can visually observe the degree of bending of the vehicle on which he / she is boarding from the driver's position, and the accuracy is 2 ° or less during a short time during transportation work. It is practically impossible to make adjustments.
Furthermore, it may be possible to determine the angle and position of the vehicle body outside the moving body and transmit it to the moving body wirelessly or the like to give initial position data. A time delay can reduce accuracy.

Hereinafter, the problems of the conventional apparatus will be described more specifically.
Here, as an example, when the vehicle approach angle (initial angle) with respect to the forward direction of the plane coordinates installed in the moving area is “2 ° to the right” at the start position of the moving body, Without being aware that the angle of the driving vehicle is tilted, the initial angle of the vehicle's self-positioning device is input to 0 ° at the start position (reset by operating the switch), and the vehicle An error when the vehicle travels straight in an angle of 0 ° will be described.

Under the above conditions, the following error occurs between the actual position when the vehicle travels straight in the direction of the plane coordinate angle 0 ° and the position coordinate of the vehicle obtained by the odometry method.
That is, at the start of travel after the reset operation, the driver unconsciously operates the steering wheel while visually observing the Y axis (straight forward) direction, and corrects the angle of the vehicle body by “2 ° to the left”. .

  Therefore, the actual vehicle body goes straight in the direction of 0 ° without causing an error with respect to the plane coordinates. However, the trend of the self-position coordinates of the vehicle body obtained by the odometry method causes the vehicle to move first. By dragging the angle movement of “2 ° leftward” at that time, the locus moves forward with an angle of 2 ° leftward.

FIG. 6 is an explanatory diagram showing the locus of the left front wheel under the above conditions as experimental data.
In FIG. 6, a broken line locus including a starting point P0, stop points P1, P2 (turnback point), and a return point P3 indicates a locus of the left front wheel when the moving body actually travels.
A solid line locus composed of the starting point P0, the stopping points P1 ′, P2 ′, and the return point P3 indicates the coordinate locus of the left front wheel of the self-position determination device based on the odometry method mounted on the moving body.

In FIG. 6, the origin (0, 0) corresponds to the center of the entrance of the plane coordinates set in the warehouse, and the Y axis indicates the straight direction from the entrance to the interior of the warehouse (backward direction).
The moving body makes a U-turn (or back turn) from the starting point P0 (X coordinate: -470 [mm]) through the stopping points P1 and P2, and returns to the return point P3 at the inlet.

  In FIG. 6, due to the initial angle error in the actual travel pattern (broken line trajectory), the self-position determination data (solid line trajectory) of the moving body by the odometry method is different from the plane (XY) coordinates set in the travel area. An error is generated between them, and in particular, the direction error of the X coordinate component increases in the vicinity of the stop points P1 ′ and P2 ′ at the tip in the traveling direction (Y-axis direction).

Although the initial angle error is about 2 °, since the XY axis scales [mm] are different from each other, the angle error in the X-axis direction with respect to the traveling direction is exaggerated.
Further, the position of the left front wheel at the return point P3 in the self-position determination data (solid line trajectory) is the X coordinate 470 [mm] because the vehicle is inverted, but is almost identical to the actual travel pattern (dashed line trajectory). Then, it has returned to the driving start position accurately.

  As described above, the position error of the self-position determination data (solid line trajectory) is more affected by the initial angle error with respect to the X-axis direction as the distance from the starting point P0 (entrance) to the Y-axis report increases. It can be seen that the management coordinates of the items stored in the back of the store are different from the actual ones.

However, the prior art does not provide any means for solving the above position determination error caused by the initial angle of the moving body. The technique simply sets the initial angle to zero, or the accumulated error by the odometry method. On the other hand, there is only a technique that focuses on correction by means of providing some absolute coordinates during traveling.
That is, in the prior art, since the moving body cannot detect its initial angle, the moving body is installed as straight as possible with respect to the plane coordinates, and the initial angle is forcibly set to zero.

"Enhanced functionality of wireless LAN location detection system" AirLocation II "" March 7, 2011, Hitachi, Ltd. "Odometry Experiment, Memorandum New version Kouhei's Homepage" July 12, 2010 (http://memo--randum.blogspot.com/2010/07/blog-post 12.htm)

A conventional self-positioning device for a mobile object based on the odometry method uses a photoelectric sensor means at the start point of the mobile body self-position determination calculation (for example, a warehouse entrance in the case of a warehouse transport vehicle). The timing of passing the point was detected, and the position coordinate data at the start point of the moving body that had been measured in advance was initially set, but the self-positioning coordinates resulting from the error in the travel start angle and the actual position in the warehouse There was a problem that the error between the plane coordinates could not be solved.
In addition, if the start angle detection device is separately installed, there is a problem that it is not practical because it causes a great increase in cost.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a mobile body self-position determination device that suppresses a mobile body position data error obtained by an odometry method. To do.

  A mobile body self-position determination device according to the present invention is a mobile body self-position determination device based on an odometry method, and includes two photoelectric sensors installed at symmetrical positions perpendicular to the traveling direction of the mobile body, and A current position recognizing device including an arithmetic processing unit for recognizing the current position of the moving body, and the current position recognizing device has two current position calculations at the start of the current position detection calculation of the moving body. Using the photoelectric sensor, the starting point coordinates and starting point angle of the moving body are calculated so as to match the coordinates and direction set in the moving area of the moving body.

  According to the present invention, in the self-position determination device for a moving body by the odometry method, the moving distance of the moving body is measured at a minute operating time difference of each photoelectric sensor that occurs when the moving body has an angle when entering the starting position. Thus, the driver of the moving body can enter the warehouse (coordinate management area where the position detection device based on the odometry method is installed and managed) without worrying about the approach angle, and at the time of passing the starting point A moving object with an initial angle is obtained by simply initializing (resetting the coordinates) the entry coordinates and entry angle at the start point of the position determination calculation (for example, warehouse entrance) in accordance with the detection signal of the photoelectric sensor, and starting the position calculation. The position error can be reduced.

It is a rear view which shows an external appearance when the self-position discrimination apparatus of the moving body which concerns on Embodiment 1 of this invention is seen from back. It is a side view which shows an external appearance when the mobile body in FIG. 1 is seen from the advancing direction left side. It is a block diagram which shows the function structure of the controller in FIG. It is explanatory drawing which shows typically the movement state of the photoelectric sensor in FIG. 1 with a top view. It is explanatory drawing which shows the change of each variable at the time of the movement of the photoelectric sensor in FIG. 1 with a table. It is explanatory drawing which shows a mode that the position error of the moving body resulting from the angle error of the conventional apparatus expands in the front-end | tip part of a advancing direction.

Embodiment 1 FIG.
FIG. 1 is a rear view showing an appearance of a self-position determining device for a moving body 10 according to Embodiment 1 of the present invention when viewed from the rear, and FIG. 2 is a view when the moving body 10 is viewed from the left side in the traveling direction. It is a side view which shows an external appearance.

In FIG. 1 and FIG. 2, as a specific example, a case where a platter type forklift vehicle is assumed as the moving body 10 and a warehouse enters from a warehouse entrance 1 having a freezer entrance slide door is shown. In addition, it is assumed that the moving body 10 itself is mounted with a system of a self-position determining device.
It should be noted that portions not directly related to the first embodiment of the present invention (for example, a means for recognizing a transported item for warehouse storage management) are not shown.

1 and 2, the moving body 10 has a left rear wheel 10rd for driving driving, an auxiliary right rear wheel 10r, a left front wheel 11, and a right front wheel (not shown). Photoelectric sensors 12 and 13 are provided on both left and right side surfaces 10 (symmetrical positions in a direction perpendicular to the traveling direction).
In addition, diffuse reflection type reflectors 14 and 15 are arranged in front of both sides of the opening and closing part of the warehouse entrance 1 so as to face the photoelectric sensors 12 and 13.

Each photoelectric sensor 12, 13 realizes a function as a reflective photoelectric sensor in cooperation with each reflector 14, 15.
A distance L1 (fixed length) between the two reflectors 14 and 15 is set to about 3 m (= 3000 mm) so that the moving body 10 can pass through the warehouse entrance 1.

  A collision preventing pole 28 and a support column 29 are installed on the front face of the door of the warehouse entrance 1, and the reflectors 14 and 15 irradiated with light emitted from the photoelectric sensors 12 and 13 are integrated with the pole 28. The support 29 is provided.

  In FIG. 2, an encoder 16 for detecting rotation is provided in the vicinity of the left front wheel 11, and a sensing ring 17 is attached to the wheel portion of the left front wheel 11 so as to face the encoder 16.

The encoder 16 detects alternating black and white stripe patterns formed on the sensing ring 17 and generates two pulse signals having a phase difference of 90 ° with each other according to the rotation of the left front wheel 11.
As long as the encoder 16 generates two pulse signals having a phase difference of 90 °, the encoder 16 is not limited to the above configuration, and other methods may be used.

In addition, the moving body 10 is provided with a battery 18 for supplying power to each part, an angle detection gyro 19, a controller 20 as a main part of the self-position determination device, and a display operation unit 30 of the controller 20. It has been.
The display controller 30 is disposed in the cab 10a of the moving body 10 and functions as a man-machine interface for the driver. The driver's cab 10a is completely surrounded by glass in a cold specification in order to protect the driver.

The gyro 19 detects a change in the angle of the plane and inputs an angle change value to an arithmetic processing unit (described later) in the controller 20 at regular time intervals.
As shown in the figure, the gyro 19 is installed horizontally with respect to the vehicle body of the moving body 10, but has a mechanism for canceling the influence of acceleration other than the change in the horizontal angle. It may be installed in the part.

FIG. 3 is a block diagram showing a functional configuration of the controller 20 according to the first embodiment of the present invention.
In FIG. 3, the controller 20 includes a power supply unit 21 that receives power from the battery 18 and a current position recognition device 22.
The current position recognition device 22 includes an arithmetic processing unit 23 including a CPU that operates by power supply from the power supply unit 21, a counter unit 24 that counts the number of pulses from the encoder 16, and an angle at which a detection signal from the gyro 19 is input. An arithmetic unit 25 and an input unit 26 for capturing detection signals from the photoelectric sensors 12 and 13 are provided.

Information through the counter unit 24, the angle calculation unit 25, the input unit 26, and the display operation unit 30 is input to the calculation processing unit 23. The arithmetic processing unit 23 notifies the driver of the self-position of the moving body 10 by displaying the calculation result on the display / operating device 30.
Note that the arithmetic processing unit 23 includes a data table 27 (described later) for calculating the angle θ of the moving body 10 as necessary.

Next, the operation according to the first embodiment of the present invention shown in FIGS. 1 to 3 will be described.
1 to 3 show only the characteristic part and its related part of Embodiment 1 of the present invention, and a device for recognizing a stored item in a warehouse, a communication device, and the like are omitted.

  First, the power supply unit 21 in the controller 20 is supplied with power from a battery 18 serving as a motive power source for the moving body 10 (forklift truck) and supplies a constant voltage power source necessary for the operation of the controller 20.

The counter unit 24 receives the pulse signal from the encoder 16, performs a reversible (up-down both directions) counting operation, and inputs the count value to the arithmetic processing unit 23.
The arithmetic processing unit 23 stores in advance movement distance data (see FIG. 5 described later) of the moving body 10 per pulse of the encoder 16 generated by the rotation of the left front wheel 11.
Note that when the power supply unit 21 is reset, the count value of the counter unit 24 is cleared.

  The angle calculation unit 25 obtains the actual angle of the mounted mobile body 10 (forklift truck) by integrating the angle change signals input from the gyro 19. At this time, it is necessary to initially set the initial angle for starting the calculation.

  The arithmetic processing unit 23 acquires data from the counter unit 24 and the angle calculation unit 25, and from the movement change amount and the angle data of the moving body 10 at a certain time interval, The movement change amount of the Y component is calculated, the calculation results are integrated, and the final self-position is output to the display controller 30.

  In addition, the arithmetic processing unit 23 interrupts and inputs the detection signals of the photoelectric sensors 12 and 13 or performs high-speed input processing of the photoelectric sensors 12 and 13 to perform an initial reset of the moving body 10.

  The display operation device 30 is a touch panel display for the driver to monitor position data and others (information necessary for warehouse management) and to perform an input operation, and functions as a terminal device of the controller 20.

FIG. 4 is an explanatory diagram schematically showing a moving state of the photoelectric sensors 12 and 13 attached to the moving body 10 in a plan view.
FIG. 5 is an explanatory diagram showing changes in variables (movement distance L2 and angle θ in FIG. 4) in a table when the photoelectric sensors 12 and 13 move.

  In FIG. 4, the reflecting plates 14 and 15 are irregular reflection types, so that even if the moving body 10 has an angle θ with respect to the ideal traveling direction (two-dot chain line arrow), the emitted light from the photoelectric sensors 12 and 13 is emitted. When irradiated, since the reflected light is returned to the photoelectric sensors 12 and 13, the photoelectric sensors 12 and 13 are activated when the moving body 10 reaches the warehouse entrance 1.

  As shown in FIG. 4, when the moving body 10 passes through the reflectors 14 and 15 at the angle θ in the direction of the broken line arrow at time t <b> 1, the optical axes (one-dot chain lines) of the photoelectric sensors 12 and 13 are If it is a straight line, it can be seen that there is a distance difference (L2) proportional to the angle θ from the operation time t1 of the photoelectric sensor 12 to the operation time t1 + Δt of the photoelectric sensor 13 ′ (after traveling by the movement distance L2).

  For example, when entering the warehouse entrance 1, the moving body 10 (see the solid line) detects the operation of the photoelectric sensor 12 at the time t1, and moves to the position 10 ′ (see the broken line) after the time Δt has passed. When the operation of the photoelectric sensor 13 ′ is detected at time t1 + Δt in which the vehicle travels straight by 130 mm), the approach angle θ of the moving body 10 is θ = 2.481 ° from the following equation (1).

θ = arctan (L2 / L1)
= Arctan (130/3000)
≒ 2.481 [deg] (1)

FIG. 5 specifically shows the relationship between the movement distance L2 (= Np × Le) and the angle θ (= arctan (L2 / L1)) for each pulse number Np.
Here, data is shown when the moving distance Le of the moving body 10 per pulse of the encoder 16 is 11.64 mm.

Even if the movable body 10 to which the photoelectric sensors 12 and 13 are attached moves in parallel with respect to the traveling direction, the distance L2 (distance difference) does not change as long as the angle θ is the same.
For example, when the moving body 10 is a transport vehicle, if the reflected lights 14 and 15 are installed on both sides of the warehouse entrance 1, when the mobile body 10 (transport vehicle) passes through the approximate center of the entrance, Even if a slight deviation occurs, it is acceptable as an error, and the most important initial angle can be obtained without being affected by the deviation when passing through the entrance.

Hereinafter, an angle determination process at the start point according to the first embodiment of the present invention will be described.
First, calculation processing of the approach angle θ to the warehouse entrance 1 when the moving body 10 enters and travels into the warehouse will be described.

In FIG. 4, considering the operation time difference Δt between the photoelectric sensors 12 and 13, the moving body 10 ″ (see the two-dot chain line) goes straight along the two-dot chain line arrow (at θ = 0) to the warehouse entrance 1. When entering, the two photoelectric sensors 12 ″ and 13 ″ operate simultaneously (Δt = 0).
On the other hand, when the vehicle enters at an angle θ, an operating time difference Δt is generated between the two photoelectric sensors 12 and 13 according to the magnitude of the angle θ as described above.

  As shown in FIG. 4, when the angle of the moving direction of the moving plane (two-dot chain line arrow) is 0 °, the moving direction angle θ of the moving body 10 when passing through the entrance is 0 ° with respect to the plane angle. By adopting a position configuration in which the photoelectric sensors 12 and 13 simultaneously operate, the moving distance L2 of the moving body 10 at a minute operating time difference Δt between the photoelectric sensors 12 and 13 generated when the moving body 10 has an angle θ. Can be measured to obtain the initial angle θ.

As a result, the position of the warehouse entrance 1 (position detection device based on the odometry method is installed and managed by the driver of the moving body 10 such as a transport vehicle with a simple configuration without worrying about the approach angle θ. It is possible to enter the coordinate management area and calculate and input the initial angle θ.
As a result, the position error of the moving body 10 can be reduced as compared with the case where the initial angle θ is ignored and zero is always input as in the conventional device.

The moving distance L2 of the moving body 10 during the operating time difference Δt is calculated by multiplying the number of pulses Np of the encoder 16 measured by the counter unit 24 during the operating time difference Δt and the moving distance Le per pulse. The
For example, when the traveling speed Vs of the moving body 10 is 4 km / h, the traveling time (time difference Δt) of 130 mm is 117 msec, but even if the traveling speed Vs of the moving body 10 changes, the count value of the encoder 16 is It does not change if the angle θ is the same.

Since the distance L1 (= 3000 mm) between the reflectors 14 and 15 is known, the photoelectric sensors 12 and 13 have passed through the reflectors 14 and 15 from arctan (L2 / L1) as in the above formula (1). Angle θ can be calculated.
By incorporating such an arithmetic processing program into the controller 20, the initial angle θ can be acquired.

As described above, the reflectors 14 and 15 that cooperate with the photoelectric sensors 12 and 13 are, for example, both sides of the sliding door of the warehouse entrance 1.
In addition, the moving body 10 that enters the warehouse entrance 1 generally travels straight, and the distance L2 that moves while the two photoelectric sensors 12 and 13 operate is very small. Therefore, it is not necessary to consider that the angle θ changes.

In the process of calculating the angle θ, the resolution of the encoder 16 becomes a problem.
Assuming that the resolution of the encoder 16 is “72 pulses per rotation of the sensing ring 17” and the outer diameter R of the left front wheel 11 is 267 mm, the moving distance Le when the encoder 16 outputs one pulse (in the arithmetic processing unit 23) The input movement distance data) is 11.64 mm from the following equation (2).

Le = π · R / 72
= 3.14 × 267/72
≈ 11.64 (2)

  Further, assuming that there is a reading error of one pulse in the above arithmetic processing, when the mutual distance L1 (= 3 m) between the reflectors 14 and 15 is used, the minimum angle discrimination error δθ is 0 from the following equation (3). .44 °.

δθ = tan−1 (2 × Le / L1)
≒ tan-1 (23.3 / 3000)
≒ 0.44 [deg] (3)

  Therefore, according to the first embodiment of the present invention, the initial angle θ can be calculated with an accuracy of 0.44 ° or more.

Next, considering the calculation processing speed, first, the traveling speed Vs of the moving body 10 when entering the warehouse entrance 1 is approaching in front of the normally closed sliding door, and has a sufficiently slow running system. Therefore, it is considered to be about 5 km / h (= 5 × 1000000/3600 [mm / sec]).
At this time, the one-pulse moving time Te of the encoder 16 is 8.3 msec from the following equation (4).

Te = Le / Vs
= 11.64 / (5 × 1000000 ÷ 3600)
≒ 0.00838 [sec] (4)

  That is, it can be seen that one pulse moving time Te requires about 8.3 msec.

Next, the initial reset process of the moving body 10 based on the detection signals from the photoelectric sensors 12 and 13 will be described.
First, an interrupt method in which each detection signal is interrupted and an initial reset process is performed can be applied.

  Since the initial angle calculation processing routine is executed with a minute operating time difference Δt between the two photoelectric sensors 12 and 13, it is necessary to execute it as an interrupt processing. The detection signal of each photoelectric sensor 12 and 13 is an interrupt input. It is effective to do.

  On the other hand, according to the cyclic processing instead of the interrupt method, since the moving distance L2 moves at a speed of 8.3 msec per pulse, when the controller 20 capable of cyclic processing of 1 msec or less is used, the interrupt is performed. The same effect can be obtained by high-speed cyclic processing instead of processing.

  The cyclic processing is effective when the controller 20 does not have an interrupt processing function, and a performance equivalent to that of the interrupt processing can be obtained by applying a cyclic processing routine.

In this case, it is necessary to synchronize the input refresh interval with the operation processing interval.
It is also effective to set a calculation completion flag after the initial angle is calculated and pass the initial angle calculation routine so as not to affect other calculation processing execution time.

In the above description, in order to calculate the angle θ, the inverse trigonometric function calculation is used as in Expression (1), but a table method may be used as shown in FIG.
As can be seen from FIG. 5, since the magnitude of the initial angle θ is about ± 3 ° at the maximum, the value of L2 / L1 (or since L1 is known, only the value of L2 or the value of only the number of pulses Np) It is also possible to store the data table 27 of the angle θ (at intervals of about 0.1 °) in the arithmetic processing unit 23 and process the corresponding angle θ by comparing the table value with the measured value.
Such a table system is also effective when the controller 20 does not have an inverse trigonometric function. In the case of the table method, it goes without saying that the table range must be interlocked (limited).

Next, specific examples of the photoelectric sensors 12 and 13 will be described.
As the photoelectric sensors 12 and 13, a transmission type and a reflection type can be considered, but only the above-described reflection type (using the reflection plates 14 and 15) is effective for the following reason.

  When the moving body 10 is a transport vehicle, a load is applied due to the weight of the item to be grasped, so that the moving body 10 is slightly tilted or sunk, but this does not affect the measurement of the initial angle θ. It is necessary to configure.

When the reflective photoelectric sensors 12 and 13 are used, it is possible to install the long reflectors 14 and 15 in the vertical direction so that the optical axes of the photoelectric sensors 12 and 13 are surely moved up and down due to the load. The photoelectric sensors 12 and 13 can be operated.
On the other hand, in the case of a transmissive photoelectric sensor (not shown), it is necessary to match the optical axes of the light projecting unit and the light receiving unit. It cannot be applied because there is a possibility of deviation.

Further, as the photoelectric sensors 12 and 13, a laser type is optimal for the following reasons.
In general, many photoelectric sensors use light-emitting diodes, and when detecting reflected light from a long distance of 1 m or more as described above, the optical axis is diffused at the time of emission. , 15 increases the light spot diameter.

  Actually, when the reflectors 14 and 15 are installed, the moving body 10 provided with the photoelectric sensors 12 and 13 is caused to travel at a low speed by setting the angle θ to 0 ° while viewing the traveling posture from the outside. It is necessary to adjust the position so that the sensors 12 and 13 are detected simultaneously.

As a specific example of the photoelectric sensors 12 and 13, for example, when using a sensor that detects a distance of about 50 mm before the optical axis at a distance of 1 m (spot diameter of 100 mm), there is no error if each value is a fixed value. Since the detection operation is performed while the moving body 10 is traveling, the optical axis is also shaken, so that some error occurs.
Therefore, when the above-described sensor is applied, it is difficult to correct the absolute angle θ of the moving body 10 in advance because it is difficult to measure the absolute angle θ at the site.

As a result, laser sensors that do not diffuse the optical axis are effective as the photoelectric sensors 12 and 13 applicable to the first embodiment of the present invention.
In the case of a laser type sensor, the spot diameter of the emitted light is sufficiently small and is 12 mm or less even at a distance of 8 m. Therefore, if the distance is about 1 m, a spot diameter of half (6 mm) or less can be expected.
Needless to say, laser-type sensors are known and are already on the market.

As described above, the self-position determining device for the moving body 10 according to the odometry method according to Embodiment 1 (FIGS. 1 to 5) of the present invention is installed at a symmetrical position perpendicular to the traveling direction of the moving body 10. And two current photoelectric sensors 12 and 13 and a current position recognizing device 22 including an arithmetic processing unit 23 for recognizing the current position of the moving body 10.
The current position recognition device 22 uses the two photoelectric sensors 12 and 13 to calculate the starting point coordinates and the starting point angle θ of the moving body 10 at the starting point of the current position detection calculation of the moving body 10. Calculations are made so as to match the plane coordinates and azimuth set in the ten moving areas.

Specifically, an encoder 16 is installed in the drive unit (the left front wheel 11) of the moving body 10.
The current position recognition device 22 acquires the moving distance L2 of the moving body 10 from the encoder 16 at the difference time Δt between the operating times of the two photoelectric sensors 12 and 13 when the moving body 10 passes through the starting point, and the moving distance L2 The starting point angle θ is calculated by inverse trigonometric function calculation using.

  Alternatively, the current position recognition device 22 has a data table 27 set in advance, acquires the movement distance L2 of the moving body 10 from the encoder 16 at each operation time difference Δt between the two photoelectric sensors 12 and 13, and moves the movement distance. The origin angle θ is calculated by performing a comparison operation with reference to the data table 27 corresponding to L2.

For example, the detection signals of the two photoelectric sensors 12 and 13 are interrupted and input to the arithmetic processing unit 23 in the current position recognition device 22 and used for calculating the starting angle θ.
Alternatively, the current position recognizing device 22 calculates the starting angle θ of the moving body 10 by using a cyclic calculation process of 1 msec or less using the detection signals of the two photoelectric sensors 12 and 13.

Further, for example, each of the two photoelectric sensors is composed of general reflection type photoelectric sensors 12 and 13 each including a reflection plate 14 and 15 and a light source integrated with light emission and reception.
Alternatively, each of the two photoelectric sensors is configured by a laser-type reflective photoelectric sensor 12 or 13 including a reflecting plate 14 or 15 and a laser-type light emitting / receiving integrated light source.

In this way, in the self-position determination device for the moving body 10 by the odometry method, the reflection type photoelectric sensor is attached to the side surface of the moving body 10, and the warehouse entrance 1 through which the optical axes of the photoelectric sensors 12 and 13 pass as the moving body 10 travels. Reflector plates 14 and 15 (or light projecting parts) for reflecting the light of the photoelectric sensors 12 and 13 are installed on both side faces (start point of the moving body 10 in the moving area) on the front side of the door part. By resetting the coordinates (initial setting) by the detection signals of the photoelectric sensors 12 and 13 when the moving body 10 passes and starting the position calculation, the moving body 10 at the warehouse entrance 1 (starting point portion of the position determination calculation) It is possible to obtain a moving body self-position discriminating apparatus capable of easily setting the approach coordinates and the approach angle θ.
In addition, the traveling direction angle (azimuth) of the moving body 10 at the position determination calculation start point can be adjusted with a small error to the angle (azimuth) set for the area that actually moves.

  As described in Non-Patent Document 2 described above, the odometry method has a basic drawback that errors accumulate. However, according to the inventor's verification, the total travel distance is about 100 m after traveling for 3 minutes or more. During the movement, the position of the moving body 10 obtained by the odometry method without any coordinate or angle correction is determined with an error within about 30 Cm in the X and Y directions from the coordinates set in the movement area. I know it is possible.

  Therefore, when the mobile body self-position determination device according to Embodiment 1 of the present invention is applied to an ultra-low temperature warehouse (freezer warehouse) having a depth and width of about several tens of meters, the above-described effects can be exhibited appropriately.

  The present invention relates to the acquisition of the initial angle θ, and although there is no particular mention of the error of the initial coordinate position, the moving body 10 passes through the center of the starting point of the plane coordinates. Then, when the moving body 10 passes through the starting point, the coordinate data of the moving body 10 at the time of passing the starting point measured in advance is forcibly set as an initial value in the self-position determining device of the moving body 10.

  In this case, although a distance error occurs due to the position of the moving body 10 deviating from the center to the left and right, the error increases as the moving body 10 moves, unlike the error of the initial angle described above (FIG. 6). Must not.

  DESCRIPTION OF SYMBOLS 1 Warehouse entrance, 10 mobile body, 10a cab, 11 left front wheel, 12, 13 photoelectric sensor, 14, 15 reflector, 16 encoder, 17 sensing ring, 18 battery, 19 gyro, 20 controller, 21 power supply part, 22 present Position recognition device, 23 calculation processing unit, 24 counter unit, 25 angle calculation unit, 26 input unit, 27 data table, 30 display operation unit, L2 moving distance, Δt difference time (operation time difference), θ angle.

Claims (7)

A self-positioning device for a moving object by an odometry method,
Two photoelectric sensors installed at symmetrical positions perpendicular to the traveling direction of the moving body;
A current position recognition device including an arithmetic processing unit for recognizing the current position of the mobile body,
The current position recognizing device uses the two photoelectric sensors at the start of the current position calculation at the current position detection calculation start point of the moving body to determine the start point coordinates and start point angle of the moving body. A self-position determination device for a moving body, characterized in that it is calculated so as to match coordinates and orientations set in an area. The mobile body self-position determination device by the odometry method includes an encoder installed in a drive unit of the mobile body,
The current position recognizing device obtains the moving distance of the moving body from the encoder at the time difference between the operating times of the two photoelectric sensors, and calculates the starting point angle by inverse trigonometric function calculation using the moving distance. The mobile body self-position determination apparatus according to claim 1, wherein the mobile body self-position determination apparatus calculates the position of the mobile body.   The current position recognizing device has a data table set in advance, obtains a moving distance of the moving body in a time difference between the operating times of the two photoelectric sensors, and the data table corresponding to the moving distance The mobile body self-position determining apparatus according to claim 1, wherein the starting angle is calculated by performing a comparison operation with reference to FIG.   The detection signals of the two photoelectric sensors are interrupted and input to an arithmetic processing unit in the current position recognition device and used for the calculation of the starting point angle. The mobile body self-position discriminating apparatus according to any one of the preceding claims.   The current position recognizing device calculates a starting angle of the moving body by a cyclic calculation process of 1 msec or less using each detection signal of the two photoelectric sensors. 4. The mobile unit self-position determination device according to any one of items 3 to 3.   6. Each of the two photoelectric sensors is configured by a reflective photoelectric sensor including a reflection plate and a light source integrated with light emission and reception, according to any one of claims 1 to 5. Self-positioning device for moving objects.   6. Each of the two photoelectric sensors is constituted by a laser type reflection type photoelectric sensor including a reflection plate and a laser type light emitting and receiving integrated light source. The self-position discriminating device for a moving body according to item 1.

Images