JP5127625B2 - Guide tape recognition device for automated guided vehicles - Google Patents

Description

  The present invention relates to a guide tape recognition device for an automatic guided vehicle (so-called AGV) guided by a guide tape laid on a floor surface and traveling in a factory or warehouse along a desired transport path. .

2. Description of the Related Art Conventionally, in a newspaper printing factory or the like, an automatic guided vehicle abbreviated as AGV is often used as a means for transporting a web from a paper storage to a rotary press.
As a traveling control method for an automated guided vehicle, (1) an electromagnetic induction wire is embedded in a floor surface, and a magnetic field generated by flowing an alternating current therethrough is detected by a magnetic sensor on the vehicle body side, thereby detecting an electromagnetic route. Guidance method (guidance wire burying method), (2) Magnetic induction method that detects the travel route by sticking magnetic tape on the floor surface as a guide wire and detecting the magnetic flux generated by the magnetic tape with the body side magnetic sensor (3) A light guiding method is mainly used in which a light reflecting tape is affixed to the floor surface as a guide line, and the light reflecting tape is detected by a light sensor on the vehicle body side to detect a travel route.
Such automatic guided vehicles have contributed to automation, labor saving, and improvement of the working environment in the conveyance of webs.

In particular, in recent years, there has been an increasing demand for rationalization of the paper feeding operation of the rotary press, and for this reason, introduction of a higher-performance automatic guided vehicle has been actively promoted.
As a control method for such an automatic guided vehicle, the magnetic induction method and the light induction method described in the above (2) and (3) are used from the viewpoint of maintenance management, adaptability to the installation site, economy, and the like. Many tend to be adopted.

Usually, a magnetic induction type or a light induction type automatic guided vehicle has a plurality of magnetic sensors or optical devices installed in a line in a direction perpendicular to the guidance tape on the guided tape made of magnetic tape or light reflecting tape. Automatic steering / running control is performed by recognizing with a sensor (see, for example, Patent Documents 1 and 2).
JP-A-9-269820 JP 2004-86453 A

The induction tape recognition device mounted on the conventional magnetic induction type or light induction type automatic guided vehicle as described above requires a plurality of sensors, and each sensor outputs characteristics one by one (for example, offset). In order to improve the detection accuracy of the guide tape recognition device, select one with a close output characteristic from many sensors when configuring one guide tape recognition device. It was necessary to use it.
For this reason, the ratio of sensors that can be actually used from many sensors, that is, the yield is low, and it takes time and labor to select the sensors, which causes an increase in manufacturing cost.

In addition, because the detection accuracy of the guide tape recognition device decreases due to subtle differences in the output characteristics of each sensor, in order to improve the detection accuracy of the guide tape recognition device, the threshold value and gain are finely adjusted for each sensor. Initial setting is required, and this initial setting requires experience and intuition by skilled workers.
Moreover, such an initial setting not only improves the detection accuracy of the guide tape recognition device to be set, but also needs to be consistent with the detection accuracy of other guide tape recognition devices, making the setting work more complicated. I was doing.

  Furthermore, the sensor of the induction tape recognition device depends on the surrounding environment (for example, in the case of a magnetic induction method, a magnetic material is present in the vicinity) and the installation environment of the induction tape (such as the material of the floor on which the induction tape is installed). Since the detection accuracy is affected, it is necessary to adjust the threshold value and gain of the sensor every time the surrounding environment of the guide tape recognition device and the installation environment of the guide tape change, and this work takes time and effort.

  Furthermore, since the detection accuracy changes due to the deterioration of the guide tape and the characteristics of the guide tape, it is necessary to adjust the guide tape recognition device according to the guide tape to be used, which requires time and effort. Was.

In addition, the conventional induction tape recognition device simply sets the sensor characteristics at the time of manufacturing the device, and cannot flexibly cope with the resetting of the sensor characteristics after operation, and some of the plurality of sensors fail. When the sensor is replaced due to the above, it is necessary to set the sensor characteristics again, and this work requires time and effort, which increases the maintenance work load.
In addition, conventional guidance tape recognition devices can flexibly respond to advanced user needs such as increasing the detection sensitivity at the left and right sides of the center of the sensor array to increase the detection accuracy of the edge of the guidance tape. It was difficult.

  In addition, the sensor property setting operation in the conventional guide tape recognition apparatus as described above must be performed in a state where the operation of the automatic guided vehicle is temporarily stopped, which causes a reduction in the operation rate of the automatic guided vehicle. It was.

  Therefore, the technical problem to be solved by the present invention, that is, the object of the present invention is to realize high detection accuracy without being affected by variations in output characteristics of a plurality of sensors, and to set the threshold value and gain of each sensor. It is an object of the present invention to provide a guided tape recognition device for an automated guided vehicle that reduces labor and time for adjustment and improves the operating rate of the automated guided vehicle.

  First, the invention according to claim 1 is an automatic guided vehicle in which the position of a guide tape laid along a transport path is recognized by a plurality of sensors installed in a row in a direction orthogonal to the guide tape. In the guide tape recognition device for use, in the state where the guide tape exists before the predetermined reference value Std (i) is stored in advance for each of the plurality of sensors and the position of the guide tape is recognized. An output value Von (i) with tape that is an output value of each of the plurality of sensors is acquired, and an output value Vof (i) without tape that is an output value of each of the plurality of sensors in a state where the guide tape does not exist. The tape-less output value Vof (i) is stored as an offset value O (i) for each of the plurality of sensors, and the tape presence / absence is stored. The difference between the value Von (i) and the tapeless output value Vof (i) is stored as a range value R (i), and a value obtained by dividing the reference value Std (i) by the range value R (i) A sensor initial setting mechanism stored as a gain value G (i), and an output value Vs (i) of each of the plurality of sensors and an offset value O (i) of the sensor when the position of the guide tape is recognized. And a sensor output correction mechanism Vx (i), which is obtained by multiplying the difference between the sensor gain value G (i) and the sensor's gain value G (i), and a correction output value Vx (i) of each of the plurality of sensors. And a tape position recognition mechanism for recognizing the position of the guide tape, and the value of the reference value Std (i) is set larger as the sensor is closer to the right end and the left end. It is.

  Here, various methods are conceivable as a method for recognizing the position of the guide tape based on the correction output values Vx (i) of the plurality of sensors. For example, the correction output values Vx ( The value of i) is compared with the predetermined threshold value Vth in order from the right, and when the corrected output value Vx (i) exceeds the threshold value Vth for the first time, the position of the sensor is recognized as the right end of the guide tape. When the corrected output value Vx (i) exceeds the threshold value Vth for the first time, the sensor output position Vx (i) is compared with a predetermined threshold value Vth in order from the left. The center of the right and left end positions of the guide tape recognized in this way is recognized as the center of the guide tape.

  The invention according to claim 2 is the guided tape recognition apparatus for automatic guided vehicle according to claim 1, wherein the tape position recognition mechanism outputs a corrected output value sandwiching a predetermined threshold value Vth. The correction output values Vx (i) and Vx (i + 1) and the positions X (i) and X (i + 1) of each of the two sensors are linearly interpolated, and the position Xth corresponding to the threshold value Vth is calculated and recognized as the end of the guide tape. By doing so, the above-mentioned problems are further solved.

  According to a third aspect of the present invention, in the guided tape recognizing device for an automatic guided vehicle according to the first or second aspect, the tape position recognizing mechanism outputs a sensor having the largest corrected output value Vx (i). By recognizing the position X (i) as the center of the guide tape, the above problem is further solved.

  In the invention according to claim 4, in the guided tape recognition device for automatic guided vehicle according to claim 1 or claim 2, the tape position recognition mechanism outputs a corrected output value exceeding a predetermined threshold value Vth. The corrected output value Vx (i) and the position X (i) of each sensor is weighted average based on Xc = ΣX (i) · Vx (i) / ΣVx (i), and the result Xc is the center of the guide tape. By recognizing, the above problem is further solved.

  Here, the mathematical formula Xc = ΣX (i) · Vx (i) / ΣVx (i) is the position and position of each corrected output value Vx (i) of the sensor that outputs the corrected output value exceeding the predetermined threshold value Vth. This means that the sum of the products of X (i) is divided by the sum of the correction output values Vx (i) of the sensors that output correction output values exceeding a predetermined threshold value Vth.

  The invention according to claim 5 is the guided tape recognizing device for automatic guided vehicle according to any one of claims 1 to 4, wherein the guide tape is a magnetic tape and the sensor is a magnetic sensor. Thus, the above problem is further solved.

  According to the first aspect of the present invention, for the automatic guided vehicle, the position of the guide tape laid along the transport path is recognized by the plurality of sensors arranged in a row in the direction perpendicular to the guide tape. In the guide tape recognition device, a predetermined reference value Std (i) is stored in advance for each of the plurality of sensors, and before the position of the guide tape is recognized, the plurality of sensors in the state where the guide tape exists. The output value Von (i) with tape that is each output value is acquired, and the output value Vof (i) without tape that is the output value of each of the plurality of sensors in the state where the induction tape does not exist is acquired. Is stored as an offset value O (i), and an output value Von (i) with tape and an output value Vof without tape are stored. a sensor initial setting mechanism for storing a difference from i) as a range value R (i), and further storing a value obtained by dividing the reference value Std (i) by the range value R (i) as a gain value G (i); When the position of the guide tape is recognized, the difference between the output value Vs (i) of each of the plurality of sensors and the offset value O (i) of the sensor is multiplied by the gain value G (i) of the sensor. A sensor output correction mechanism whose value is the correction output value Vx (i) of the sensor, and a tape position recognition mechanism that recognizes the position of the guide tape based on the correction output values Vx (i) of the plurality of sensors. Since the value of the reference value Std (i) is set to be larger as the sensor is closer to the right end and the left end, the following special effects corresponding to the configuration specific to the invention according to claim 1 can be obtained. Can do.

First, the sensor initial setting mechanism eliminates the effects of variations in the output characteristics (offset value, sensitivity, output range) of multiple sensors, so that high detection accuracy can be achieved, and many sensor There is no need to select the one with the similar output characteristics from the inside, and the manufacturing cost of the apparatus can be reduced.
Furthermore, since the output characteristics of each of the plurality of sensors can be arbitrarily set simply by changing the value of the reference value Std (i), the sensitivity characteristics of the recognition tape recognition device can be flexibly changed.
In addition, since the value closer to the right end and the left end is set to a larger value for the reference value Std (i), the output value becomes larger as the sensor is closer to the right end and the left end. Sensitive to detect.

  In addition, the offset adjustment of each sensor and the normalization of the output range are performed using an arithmetic circuit, so that the initial setting work of finely adjusting the threshold value and gain for each sensor is greatly reduced, and the induction tape is changed. It can respond quickly and easily to aging and deterioration, and the maintenance burden is greatly reduced.

  Furthermore, since the initial setting operation of the sensor can be performed in a short time in the middle of the conveyance route of the automatic guided vehicle, the operation rate of the automatic guided vehicle can be improved.

  Also, according to the invention according to claim 2, in the guided tape recognition device for automatic guided vehicle according to claim 1, the tape position recognition mechanism is adjacent to the output of the corrected output value sandwiching the predetermined threshold value Vth. The correction output values Vx (i) and Vx (i + 1) and the positions X (i) and X (i + 1) of the two sensors are linearly interpolated, and the position Xth corresponding to the threshold value Vth is calculated and recognized as the end of the guide tape. By doing so, the position of the edge existing between two adjacent sensors sandwiching the edge of the guide tape is reasonably estimated, so that high detection accuracy can be realized without increasing the number of sensors. .

  According to the invention of claim 3, in the guided tape recognition device for automatic guided vehicles according to claim 1 or claim 2, the tape position recognition mechanism outputs the largest corrected output value Vx (i). By recognizing the sensor position X (i) as the center of the guide tape, the corrected output value Vx (i) of each sensor is removed from the offset range and the output range is set to the reference value Std (i). Since it is normalized, the center of the guide tape can be recognized by a simple comparison of the magnitude of the corrected output value Vx (i), and the calculation speed for recognition of the position of the guide tape can be increased. can do.

According to the invention according to claim 4, in the guided tape recognition device for automatic guided vehicle according to claim 1 or claim 2, the tape position recognition mechanism outputs a corrected output value exceeding a predetermined threshold value Vth. The corrected output value Vx (i) and the position X (i) of each sensor being weighted and averaged based on Xc = ΣX (i) · Vx (i) / ΣVx (i) By recognizing, the influence of the sensor showing a unique value is reduced, and therefore, it is less susceptible to noise caused by scratches on the induction tape, dirt on the sensor element, or the like.
In addition, since the center position of the actual guide tape existing between the sensors can be reasonably estimated by the weighted average, high detection accuracy can be realized without increasing the number of sensors.

  According to the invention of claim 5, in the guided tape recognition device for automatic guided vehicle according to any of claims 1 to 4, the guide tape is a magnetic tape and the sensor is a magnetic sensor. Thus, the automatic guided vehicle can be accurately guided and controlled without being affected by the illuminance of the environment in which the automatic guided vehicle is used or the contamination of the guide tape.

  The present invention relates to a guided tape recognition device for an automated guided vehicle that recognizes the position of a guided tape laid along a conveyance path with a plurality of sensors installed in a row in a direction orthogonal to the guided tape on the automated guided vehicle. A predetermined reference value Std (i) is stored in advance for each of the sensors, and the tape is an output value of each of the plurality of sensors in the state where the guide tape exists before the position of the guide tape is recognized. The present output value Von (i) is obtained, and the tapeless output value Vof (i), which is the output value of each of the plurality of sensors in the state where the induction tape does not exist, is obtained, and the tape is obtained for each of the plurality of sensors. The output value Vof (i) having no tape is stored as an offset value O (i), and the difference between the output value Von (i) having a tape and the output value Vof (i) having no tape is set as a range. R (i) is stored as a sensor initial setting mechanism for storing a value obtained by dividing the reference value Std (i) by the range value R (i) as a gain value G (i), and recognition of the position of the guide tape. When performing, a value obtained by multiplying the difference between the output value Vs (i) of each of the plurality of sensors and the offset value O (i) of the sensor by the gain value G (i) of the sensor is a corrected output value of the sensor. By having a sensor output correction mechanism for Vx (i) and a tape position recognition mechanism for recognizing the position of the guide tape based on the corrected output values Vx (i) of the plurality of sensors, the output characteristics of the plurality of sensors If it is possible to achieve high detection accuracy without being affected by variations in the sensor, reduce the time and effort of adjusting the threshold and gain of each sensor, and improve the operation rate of automated guided vehicles Mode of implementation , Be any thing, it does not matter at all.

Example 1 which is one embodiment of the present invention will be described with reference to FIGS.
Here, FIG. 1 is a conceptual diagram showing an outline of an automated guided vehicle to which the guided tape recognition device for automated guided vehicles of the present embodiment is applied.
FIG. 2 is a plan view showing a positional relationship between the sensor and the guide tape at the time of initial setting of a plurality of sensors, and FIG. 3 is a positional relationship between the sensor and the guide tape when the position of the guide tape is recognized. FIG. 4 shows the difference between the output values of the plurality of sensors when the guide tape is present and the output values of the sensors when the guide tape is not present. FIG. 5 is a flowchart showing a flow of sensor initial setting, and FIG. 6 is a flowchart showing a flow of recognizing the position of the guide tape from the sensor output value. FIG. 7 is a graph showing a difference in sensor output value due to a difference in the induction tape, FIG. 8 is a setting example of the reference value Std (i), and FIG. 9 is a graph showing different reference values Std (i). Set an example.

  As shown in FIG. 1, the guided tape recognition apparatus for an automatic guided vehicle according to the present embodiment is guided by a guide tape G made of a magnetic tape laid on a floor surface along a desired transport path in a newspaper printing factory or the like. It is mounted on a magnetic induction type automatic guided vehicle 100 that travels and used for recognizing the position of the induction tape G.

In the automatic guided vehicle 100, caster wheels 110 are arranged at four corners, and a magnetic sensor array 120 in which 16 magnetic sensors are arranged in a row is installed between the front and rear caster wheels 110.
In addition, drive wheels 130 that are driven to rotate by the electric motor 140 are installed at substantially the center of the left and right sides of the automatic guided vehicle 100.
In the present embodiment, the magnetic sensor array 120 uses 16 magnetic sensors (hereinafter also referred to as “elements”) arranged in a line at intervals of 10 mm.

Next, the flow for recognizing the position of the guide tape by the guided tape recognition device for automatic guided vehicles according to the present embodiment will be described with reference to FIGS.
In the following description, the reference numerals shown in [] indicate the flow numbers shown in the flowcharts of FIGS.
Further, i represents an element number. In the present embodiment, i = 1 to 16.

First, a reference value Std (i) is set for each magnetic sensor constituting the magnetic sensor array 120 [S1].
In this embodiment, the reference value Std (i) for all magnetic sensors is set to 1000 mV.
Then, as shown in FIG. 2A, the output value of each magnetic sensor constituting the magnetic sensor array 120 in the state where the induction tape G exists, that is, the output value Von (i) with tape is acquired [S2]. .
Next, as shown in FIG. 2B, the output value of each magnetic sensor constituting the magnetic sensor array 120, that is, the output value without tape Vof (i) is obtained in the absence of the induction tape [S3]. .
Here, FIG. 4A is a graph showing the values of Von (i) and Vof (i) for each magnetic sensor.
As is apparent from this graph, the output values vary considerably from one magnetic sensor to another.

Then, each Vof (i) of each magnetic sensor is stored as an offset value O (i) [S4].
Further, the difference between Von (i) and Vof (i) is stored as a range value R (i) [S5].
FIG. 4B shows a graph of the range value R (i) for each magnetic sensor.
As is apparent from this graph, the range value R (i) for each magnetic sensor is about 1100 mV.

Furthermore, in order to reduce the error of the measurement result due to the variation of the range value R (i) for each magnetic sensor, the gain value G for normalizing the range value R (i) for each magnetic sensor to the reference value Std (i). (I), that is, a value obtained by dividing the reference value Std (i) by the range value R (i) is obtained and stored as the gain value G (i) [S6].
Here, the meaning of “normalize to the reference value Std (i)” means that all range values R (i) that vary for each magnetic sensor are aligned with the predetermined reference value Std (i). In other words, the range value R (i) larger than the reference value Std (i) is reduced, and the range value R (i) smaller than the reference value Std (i) is enlarged to the reference value. Align to Std.
The magnification at that time is the gain value G (i).
The above steps [S1] to [S6] are performed by the sensor initial setting mechanism.

After the sensor initial value setting is completed, the induction tape is recognized.
At this time, as shown in FIG. 3, the magnetic sensor array 120 is installed in a direction orthogonal to the guide tape G.
And each output value Vs (i) of each magnetic sensor is acquired [S7].

Next, a value obtained by multiplying the difference between the output value Vs (i) of each magnetic sensor and the offset value O (i) of the magnetic sensor by the gain value G (i) of the magnetic sensor is calculated [S8]. The value is set as a corrected output value Vx (i) of the magnetic sensor [S9].
Here, the corrected output value Vx (i) represents an output value when the range value R (i) of each magnetic sensor is normalized to the reference value Std (i).
That is, the correction output value Vx (i) of each magnetic sensor can be considered as a relative value with respect to the reference value Std (i).
The above steps [S7] to [S9] are performed by the sensor output correction mechanism.

Further, based on the corrected output value Vx (i) of each magnetic sensor, the tape deviation, that is, the center position and the left and right end positions of the guide tape are obtained by calculation [S10], and the result is output [S11].
Steps [S10] and [S11] are performed by the tape position recognition mechanism.
In the present embodiment, the following method is used as a calculation method for obtaining the center position and the left and right end positions of the guide tape from the correction output value Vx (i) of each magnetic sensor.

The value of each corrected output value Vx (i) of each magnetic sensor is compared with a predetermined threshold value Vth in order from the right. When the corrected output value Vx (i) exceeds the threshold value Vth for the first time, the position of the magnetic sensor is determined. Recognized as the right end position of the guide tape.
Similarly, when the correction output value Vx (i) of each magnetic sensor is compared with the predetermined threshold value Vth in order from the left, and when the correction output value Vx (i) exceeds the threshold value Vth for the first time, the magnetic sensor Is recognized as the left end position of the guide tape.
By doing so, the right end position and the left end position can be accurately recognized even when the guide tape is branched.
The center of the right end position and the left end position of the guide tape recognized in this way is recognized as the center position of the guide tape.
In addition, the position X (i) of the sensor that outputs the corrected output value Vx (i) that is equal to or greater than the threshold value Vth and the corrected output value Vx (i) are weighted and averaged based on the following equation, and the result is the center position Xc of the guide tape. You may recognize.
Xc = ΣX (i) · Vx (i) / ΣVx (i)

Note that the value of the threshold value Vth can be determined by a ratio of n% of the maximum value of the reference value Std (i).
In the case of the present embodiment, the reference value Std (i) is 1000 mV (constant), and the threshold value Vth is 30% of 300 mV.
The detection accuracy varies depending on the magnitude of the threshold value Vth.
Therefore, prior to the actual detection of the position of the guide tape, the detection accuracy is improved by changing the size of the threshold value Vth so that the position of the guide tape obtained by calculation matches the position of the actual guide tape. Can be made.

The output value of the magnetic sensor is affected by the difference in the thickness and material of the induction tape (magnetic tape) and the aging of the induction tape.
For example, FIG. 7A is a graph showing the output value of each magnetic sensor when a magnetic tape having a thickness of 1 mm is used, and FIG. 7B shows a magnetic tape having a thickness of 0.7 mm. The output value of each magnetic sensor at the time of using is graphed.
As is clear from the comparison between the two, the output of the magnetic sensor is affected by the characteristics of the magnetic tape.
Therefore, the detection accuracy can be improved by resetting the initial value by the above-described sensor initial setting mechanism when the guide tape is changed or every time the operation time has passed. The effect is enormous.

  In the above-described example, the reference value Std (i) of each magnetic sensor constituting the magnetic sensor array is set to 1000 mV (constant). However, as shown in FIG. 8, the reference value Std (i) of each magnetic sensor. By setting the sensor closer to the right end and the left end, it is more sensitive to deviations at the left and right ends, and the tolerance of accuracy is wide near the center, so it is difficult to derail from the guide tape for guidance of automated guided vehicles. , Stability during high speed running can be improved.

  Furthermore, as shown in FIG. 9, when the reference value Std (i) of each magnetic sensor is set larger as it is closer to the right end, the right side deviation becomes sensitive and suppresses the situation where the guide tape is derailed to the right side. This is effective when there is room on the left side of the road, but there is an opposite lane on the right side of the road and you do not want to be off the road.

Next, Example 2 which is another embodiment of the present invention will be described with reference to FIGS.
The guided tape recognizing device for the automatic guided vehicle according to the second embodiment is different from the guided tape recognizing device for the automatic guided vehicle according to the above-described first embodiment only in the tape position recognizing device. To do.

The guided tape recognizing device for automatic guided vehicle according to the present embodiment recognizes the end and center of the magnetic tape by the following method.
After the correction output value Vx (i) of each magnetic sensor is obtained, the respective correction output values Vx (i) and Vx (i + 1) of two adjacent magnetic sensors that output the correction output value sandwiching the threshold value Vth. And positions X (i) and X (i + 1) are obtained.
Based on these four values, the position Xth corresponding to the threshold value Vth is calculated by the following equation.
Xth = {(Vx (i + 1) -Vth) .X (i) + (Vth-Vx (i)). X (i + 1)} / (Vx (i + 1) -Vx (i))

Xth calculated by this equation is recognized as the end of the magnetic tape.
The above calculation formula finds a point that internally divides the distance (X (i + 1) −X (i)) of two sensors by a ratio of (Vx (i + 1) −Vth) :( Vth−Vx (i)). There is nothing else.
That is, as shown in FIG. 10, the relationship between the positions X (i + 1) and X (i) of the two adjacent magnetic sensors and the correction output values Vx (i + 1) and Vx (i) is linearly interpolated to obtain the threshold value Vth. The corresponding position Xth is calculated, and this position Xth is recognized as the end of the magnetic tape.
By recognizing the end of the magnetic tape in this way, the detection accuracy can be improved without increasing the number of magnetic sensors, and the effect is enormous.

The center of the right end position and the left end position of the magnetic tape determined by such a method is recognized as the center position of the magnetic tape.
Alternatively, the position X (i) of the magnetic sensor that outputs the largest corrected output value Vx (i) may be recognized as the center of the magnetic tape.

Next, using the magnetic tape arranged as shown in FIG. 11, the right end position, left end position and center position of the magnetic tape were calculated by the above method.
The result is shown in FIG. 12 together with the actual value.
In calculating the center position, the position X (i) of the magnetic sensor that outputs the largest corrected output value Vx (i) is set as the center of the magnetic tape.

As is apparent from FIG. 12, the center position is correctly calculated in the linear portion (y = 0 to 50 mm) of the magnetic tape.
Further, the right end position and the left end position of the magnetic tape have an error of about 9 mm with respect to the actual value, but the value is constant in the entire measurement region.
This is an error caused by setting the threshold value to 300 mV. Prior to implementation, the threshold value is adjusted once (zero point adjustment), and the calculated value and the actual value are matched to reduce the error. Is possible.
In the case of this example, the error between the calculated value and the actual value could be 1 mm or less.

On the other hand, in the magnetic tape branch region (y = 50 to 300 mm range), the calculated value of the center position is different from the actual value.
This is because, in the branch region, the magnetic sensor array measures the two magnetic tapes after the branch.
However, in the branch region, there is no operational problem because the vehicle travels while following the right end position or the left end position of the magnetic tape according to the traveling route (the right route or the left route after the branch).
In FIG. 12, the tape right end position is constant at 300 mm when y = 250 mm or more because the sensor width is set to 300 mm in this embodiment, and no further calculation is possible.

In the present embodiment, two adjacent magnetic sensors indicating binary values that include the threshold value Vth are specified, and the corrected output values Vx (i), Vx (i + 1) and the position X (i) of the two magnetic sensors, The right end position or the left end position is obtained by linearly interpolating X (i + 1) and calculating the position Xth corresponding to the threshold value Vth, but interpolating with a quadratic curve or a cubic curve using the spline interpolation method. It is also possible.
However, when the sensor interval is set to 10 mm as described above, linear interpolation is sufficient for practical use because positioning accuracy of 1 mm corresponding to one-tenth of the sensor interval can be obtained by linear interpolation.
Moreover, linear interpolation is preferable because the calculation method is simple and the calculation processing speed can be increased.

Next, Example 3, which is still another embodiment of the present invention, will be described with reference to FIG.
The guided tape recognizing device for the automatic guided vehicle according to the third embodiment is different from the guided tape recognizing device for the automatic guided vehicle according to the above-described first embodiment only in the tape position recognizing device. To do.

  In the first and second embodiments described above, the description has been made on the assumption that the right end position and the left end position of the guide tape are within the sensor detection width. However, as shown in FIG. When there is a tape center position and a left end position, the center position and the left end position of the magnetic tape are estimated and output based on the value of the right end position of the magnetic tape detected within the sensor detection width.

  For example, in this embodiment, the position obtained by adding the known magnetic tape width L to the right end position X1 of the magnetic tape detected within the sensor detection width is estimated as the left end position X3 of the magnetic tape. The position obtained by adding one-half is estimated as the center position X2 of the magnetic tape.

Next, a fourth embodiment which is still another embodiment of the present invention will be described with reference to FIGS.
The guided tape recognizing device for the automatic guided vehicle according to the fourth embodiment is different from the guided tape recognizing device for the automatic guided vehicle according to the above-described first embodiment only in the sensor initial setting mechanism. Therefore, only the sensor initial setting mechanism will be described below. To do.

When the magnetic tape is laid on the boundary between the magnetic iron plate and the non-magnetic concrete, the magnetic sensor array is obtained by recognizing the position of the induction tape with the induction tape recognition device described in the first embodiment. The magnetic flux from the magnetic tape laid on the iron plate is detected more sensitively than the magnetic flux from the magnetic tape laid on the concrete. The tape position is recognized.
Therefore, when acquiring the taped output value Von (i) in S2 of the flow of FIG. 5, as shown in FIG. 14, a guiding tape is laid on the boundary between the iron plate and the concrete, and a magnetic sensor is placed on this guiding tape. An output value Von (i) with tape is acquired with the arrays facing each other.
As a result, the taped output value Von (i) from the iron plate side magnetic sensor is larger than the taped output value Von (i) from the concrete side magnetic sensor.
Therefore, the range value R (i) obtained in S5 of the flow of FIG. 5 is the range value R (i) of the magnetic sensor on the iron plate side, as shown in FIG. ).
Since the gain value G (i) obtained in S6 of the flow of FIG. 5 is a value proportional to the reciprocal of the range value R (i), the gain value G (i) of the iron plate side magnetic sensor is equal to the concrete side. It becomes smaller than the gain value G (i) of the magnetic sensor.
Therefore, when the corrected output value Vx (i) is obtained in S8 of the flow of FIG. 6, the output value of the iron plate side magnetic sensor is corrected so as to be smaller than the output value of the concrete side magnetic sensor.
As a result, the magnetic sensor array detects the magnetic flux from the magnetic tape laid on the iron plate more sensitively than the magnetic flux from the magnetic tape laid on the concrete. The position of the near magnetic tape can be recognized.

In the above-described example, the case where the flooring material is an iron plate and concrete has been described. However, the present invention is not limited to this and can be applied to various materials such as stainless steel and synthetic resin, and iron plate and wood.
And when passing through areas with different floor materials on the right and left sides of the induction tape, by obtaining the output value Von (i) with tape before entering the area, the automatic guided vehicle can be accurately You can drive the area.

Furthermore, this method can be applied not only to correct the deviation of the sensitivity characteristic of the magnetic sensor array due to the difference in flooring material, but also to the case where the thickness of the induction tape is different on the left and right.
That is, for example, when using a guide tape whose left side is thicker than the right side, by using a guide tape whose left side is thicker than the right side, by obtaining the tape output value Von (i), The difference in the output of the magnetic sensor due to the difference in the thickness of the induction tape is corrected, and the position of the magnetic tape closer to the actual can be recognized.

  According to this embodiment, it is not necessary to previously store the floor material and the characteristics of the guide tape in the automatic guided vehicle, and the tape output value Von ( Only by performing the initial setting of obtaining i), the position of the magnetic tape closer to the actual can be recognized, and the effect is enormous.

  In the embodiment described above, an example of a magnetic induction method using a magnetic tape as a guide tape and a magnetic sensor as a sensor has been described. However, even with a light guide method using a reflective tape and an optical sensor, The same applies.

  In addition, when acquiring the output value of each sensor, the output value acquired once is not used as it is, but the average value obtained by averaging multiple times acquired is used as an output value. This is preferable because the detection accuracy is improved.

  Furthermore, the difference between the outputs of adjacent sensors is constantly monitored during operation of the automatic guided vehicle guide tape recognition device of the present invention and when the sensor is initially set, and the value becomes larger than a preset value. Sometimes, it is possible to improve the reliability of the apparatus by providing a failure diagnosis function that gives a warning that a sensor has failed.

The conceptual diagram of the automatic guided vehicle to which the induction | guidance | derivation tape recognition apparatus for automatic guided vehicles of Example 1 is applied. The top view which showed the positional relationship of the sensor and guide tape at the time of the initial setting of a some sensor. The top view which showed the positional relationship of a sensor and a guidance tape at the time of recognizing the position of a guidance tape. The graph which showed each output value of the some sensor in the state where a guide tape exists, each output value of the some sensor in the state where a guide tape does not exist, and the range value R (i) which is a difference of both. The flowchart which showed the flow of the sensor initial setting. The flowchart which showed the flow which recognizes the position of a guidance tape from a sensor output value. The graph which showed the difference in the sensor output value by the difference in the induction tape. Setting example of reference value Std (i). Another setting example of the reference value Std (i). FIG. 6 is a diagram illustrating linear interpolation according to the second embodiment. The figure which showed arrangement | positioning of the magnetic tape and sensor which were used for the positioning accuracy test of Example 2. FIG. 6 is a graph showing the results of a positioning accuracy test of Example 2. FIG. 6 is a diagram for explaining a magnetic tape position estimation method according to a third embodiment. FIG. 10 is a diagram illustrating a method for setting an output value Von (i) with tape according to the fourth embodiment. The graph which showed the range value R (i) of Example 4. FIG.

DESCRIPTION OF SYMBOLS 100 ... Automated guided vehicle 110 ... Caster wheel 120 ... Magnetic sensor array 130 ... Drive wheel 140 ... Electric motor G ... Induction tape

Claims (5)

In the guided tape recognition device for automated guided vehicles, which recognizes the position of the guided tape laid along the transport path with a plurality of sensors installed in a row in a direction orthogonal to the guided tape on the automated guided vehicle,
A predetermined reference value Std (i) is stored in advance for each of the plurality of sensors, and each of the plurality of sensors in a state where the guide tape exists before the position of the guide tape is recognized. An output value Von (i) with a tape that is an output value is acquired, an output value Vof (i) without a tape that is an output value of each of the plurality of sensors in a state where the guide tape does not exist, For each sensor, the tapeless output value Vof (i) is stored as an offset value O (i), and the difference between the taped output value Von (i) and the tapeless output value Vof (i) is calculated. A sensor initial setting machine that stores a value obtained by dividing the reference value Std (i) by the range value R (i) as a gain value G (i). And,
When recognizing the position of the guide tape, the difference between the output value Vs (i) of each of the plurality of sensors and the offset value O (i) of the sensor is multiplied by the gain value G (i) of the sensor. A sensor output correction mechanism that sets the calculated value as the correction output value Vx (i) of the sensor;
A tape position recognition mechanism for recognizing the position of the guide tape based on the corrected output values Vx (i) of the plurality of sensors,
The guide tape recognition device for an automatic guided vehicle, wherein the value of the reference value Std (i) is set larger as the sensor is closer to the right end and the left end.   The tape position recognition mechanism outputs correction output values Vx (i) and Vx (i + 1) and positions X (i) and X (2) of two adjacent sensors that output correction output values sandwiching a predetermined threshold value Vth. 2. The guided tape recognition apparatus for an automatic guided vehicle according to claim 1, wherein i + 1) is linearly interpolated and a position Xth corresponding to the threshold value Vth is calculated and recognized as an end of the guided tape.   3. The unmanned system according to claim 1, wherein the tape position recognition mechanism recognizes the position X (i) of a sensor that outputs the largest corrected output value Vx (i) as the center of the guide tape. Guide tape recognition device for transport vehicles. The correction output value Vx (i) and the position X (i) of the sensor from which the tape position recognition mechanism outputs a correction output value exceeding a predetermined threshold value Vth is expressed as Xc = ΣX (i) · Vx (i ) / ΣVx (i)
The guided tape recognition device for an automatic guided vehicle according to claim 1 or 2, wherein a result Xc obtained by weighted averaging based on the information is recognized as a center of the guide tape.   The induction tape recognition device for an automatic guided vehicle according to any one of claims 1 to 4, wherein the induction tape is a magnetic tape, and the sensor is a magnetic sensor.

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