JP2000055649A - Device for measuring length of moving body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance reliability of length measurement for a moving body. SOLUTION: This measuring device is provided with a rear end detector 3 and front end detectors 4 for detecting a rear end 1b and a front end 1a of a moving body 1, a speed detector 5 for detecting a moving speed, a lapse time measuring instrument 10 for counting the lapse of time after the front end is detected, and a moving body-length calculating part. The device is provided with a present length calculating part 14 for calculating the length of the moving body 1 in respective times based on the number of the front end detectors 4 by which the front end is already detected at the respective times and their specified distance L, and based on a lapse time (t) after a detection time in the front end detector 4 by which the front end is detected at last at the respective times and its moving speed, a detector predicting part 17 for predicting the front end detector 4 to detect the front end next, and a detection result determining part 11 for suspending calculation operation of the moving body-length calculating part when the front end detector 4 other than the predicted front end detector 4 detects the front end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a moving object length measuring device for measuring the length of a moving object.

[0002]

2. Description of the Related Art The simplest method of measuring the length of a long product manufactured in a manufacturing factory online, for example, is to freely rotate a long moving object being conveyed on a roller conveyor. A method of calculating the length of the moving object by pressing the rotating roll, measuring the rotating speed of the rotating roll, and multiplying the measured rotating speed by the outer circumference of the rotating roll is considered.

However, in this method, when the rotating roll is operated for a long period of time, there is a problem that the outer diameter of the rotating roll changes due to abrasion or the like, and the length measurement accuracy is reduced. Further, the measurement accuracy of the length of the moving object depends on the dimensional accuracy of the rotating roll. Since the outer diameter of the rotating roll cannot be set so large, its dimensional accuracy is at most 0.
It is about 1%. As a result, the measurement accuracy of the length of the moving object is also about 0.1%.

[0004] Depending on the surface condition of the moving object, the rotating roll may not rotate normally due to slippage or the like. Therefore, in such a case, there is a concern that the measured length is shorter than the actual length.

In order to solve such inconvenience, a non-contact speedometer and a pair of edge detectors for detecting the front and rear ends of a moving object are used instead of the rotating roll.
A method of calculating the length of the moving object by multiplying the detected speed by the required time from the leading edge detection to the trailing edge detection can be considered.

However, also in this method, since the accuracy of length measurement depends on the accuracy of speedometer measurement, as described above, the accuracy of measurement is at most about 0.1%. In order to solve such inconvenience, a moving object length measuring device in which one rear end detector and a plurality of front end detectors are arranged at a predetermined distance from each other in the moving direction of the moving object is considered ( JP-A-4-29001).

That is, as shown in FIGS. 2 and 3, a single rear end detector 3 and a plurality of rear end detectors 3 are provided along a transport path 2 comprising a number of roller conveyors 2a for a moving object 1 such as a long steel plate. A table tip detector 4 is provided. The distance between the detectors 3 and 4 is accurately set to a predetermined distance L.

The rear end detector 3 detects the rear end 1b of the moving object 1 carried into the conveyance path 2 from the left in a non-contact manner. Also,
Each tip detector 4 detects the tip 1a of the moving object 1 carried into the transport path 2 from the left in a non-contact manner.

Further, a speed detector 5 for measuring the speed V of the moving object 1 in a non-contact manner is provided on the rear end detector 3 side of the first front end detector 4. The plurality of tip transfer devices 4 sequentially detect the tip 1a of the moving object 1 carried into the transport path 2 from the left, and the tip detection time of the tip detector 4 that finally detects the tip 1a. An elapsed time measuring unit 9 for measuring an elapsed time t from the time is provided.

Next, the measuring operation in the moving object length measuring apparatus having such a configuration will be described. FIG. 2 shows the transport path 2
Shows a state in which the tip 1a of the moving object 1 has not been carried in yet. In this state, the detectors 3 and 4 have not detected the rear end 1b or the front end 1a of the moving object 1. And
Each time the tip 1a of the moving object 1 passes through the position of each tip detector 4 on the transport path 2, the tip detector 4 at the corresponding position outputs a tip detection signal. The number of detections N of the tip detection signal is counted. Further, the elapsed time measuring unit 9 measures the elapsed time t from the tip detection time of the tip detector 4 that finally detected the tip 1a.

Then, as shown in FIG. 3, when the rear end 1b of the moving object 1 reaches the position of the rear end detector 3, the rear end detector 3 detects the rear end 1b. At this point, as shown in FIG. 3, the tip 1a of the moving object 1 is located between the N-th tip detector 4 and the (N + 1) -th tip detector 4. Further, it is assumed that the elapsed time measuring unit 9 measures the elapsed time t from the time when the N-th tip detector 4 finally detected the tip 1a.

When the rear end detector 3 detects the rear end 1b, the length L ₀ of the moving object 1 is calculated in the following procedure. That is, since the distance between the detectors 3 and 4 is exactly the specified distance L, the distance from the rear end 1b of the moving object 1 to the N-th front end detector 4 is exactly N · L. further,
The distance ΔL from the Nth tip detector 4 to the tip 1a of the moving object 1 is a value t · V obtained by multiplying the elapsed time t by the speed V at that time. Therefore, the length L ₀ of the moving object 1 is obtained by the following equation.

L ₀ = N · L + ΔL = N · L + t · V In the above equation, assuming that the position detection error of each of the detectors 3 and 4 is negligible, the first term (N · L) on the right side
Can be regarded as having almost no error. The error is only the second term (tV) on the right side. Since the second term (tV) on the right side is much smaller than the first term (NL) on the right side, even if the error of the second term (tV) is 0.1% , The error of the entire length L ₀ of the moving object 1 is much lower than 0.1%.

[0014]

However, FIG.
The moving object length measuring device shown in FIG. 3 also has the following problems to be improved. That is, the environment in which the moving object length measuring device is installed is very bad, for example, in the case of a manufacturing factory or the like. Particularly at a manufacturing site or the like, mechanical vibration is large, and the conveyor belt 2a of the transport path 2 vibrates up, down, left, and right.

As a result, the leading end 1a and the trailing end 1b cannot be detected in the order in which the detectors 3 and 4 are arranged. There is a concern that rectification may occur or a malfunction may occur in which one tip detector 4 instantaneously detects the same edge twice.

As described above, if the edge detection omission or overlap detection exists in each of the tip detectors 4, the length L ₀ of the moving object 1 cannot be calculated accurately. In addition, besides mechanical vibration, in a work environment where there is a lot of dust,
In the case where 4 detects the edge of the moving object 1 by an optical method, since the dust blocks the light beam, each detector 3
4 malfunctions, and the tip 1a of the moving object 1 is detected even though the tip 1a has not actually reached. As a result, the calculated length L ₀ of the moving object 1 becomes longer than the actual length.

The present invention has been made in view of such circumstances, and by always measuring the position of the tip of a moving object, it is possible to predict the tip detector that will detect the next tip, and to perform erroneous detection. It is an object of the present invention to provide a moving object length measuring device that can prevent the length of a moving object from being calculated as a result, and can greatly improve the reliability of the measurement result.

[0018]

SUMMARY OF THE INVENTION The present invention provides a rear end detector for detecting a rear end of a moving object and a rear end detector for detecting a rear end of the moving object. A plurality of tip detectors, a speed detector that detects the moving speed of the moving object, and an elapsed time measuring device that counts the elapsed time since each tip detector detects the tip of the moving object,
The rear-end detector detects the rear end of the moving object, and at this time, the number of the front-end detectors that have already detected the front-end, the specified distance, and the elapsed time from the front-end detector that last detected the front-end were measured. The present invention is applied to a moving object length measuring device including a moving object length calculating unit that calculates the length of a moving object from a moving speed.

In order to solve the above-mentioned problem, in the moving object length measuring apparatus according to the present invention, after the first one of the plurality of tip detectors detects the tip of the moving object, At each time in the period until the end detector detects the rear end of the moving object, from the number of front end detectors that have already detected the front end, the specified distance, and the front end detector that finally detects the front end at the corresponding time A current length calculation unit that calculates the length of the moving object at each time from the elapsed time and the measured moving speed, and based on the length of each time calculated by the current length calculation unit, A detector predictor for predicting the tip detector to be detected, and a moving object length calculator for calculating a moving object length calculator when a tip detector other than the tip detector predicted by the detector predictor next detects the tip of the moving object. A detection result determination unit that stops operation To have.

In the moving object length measuring apparatus thus constructed, after the leading end of the moving moving object has passed the initial position of the leading end detector, the trailing end is located at the position of the trailing end detector. At each time before passing through the position, it can be grasped between what number of the tip detector and the number of the tip detector of the moving object moving in the length measuring device. Therefore, it is possible to predict a tip detector that detects the tip next.

Therefore, when a detector other than the predicted tip detector detects the tip, the tip detector is not a tip detector which should be originally detected due to, for example, vibration, dust or dirt. Since it is determined that the leading end has been detected, the operation of calculating the length of the moving object using the detection result is stopped.

Accordingly, it is possible to prevent the length of the moving object from being calculated based on an erroneous detection result. In another invention, the rear end detector and the front end detector are constituted by optical detectors utilizing the fact that light is shielded by the presence of a moving object. Thus, the position detection accuracy can be improved by using the optical detector.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a moving object length measuring device according to an embodiment of the present invention. The same parts as those of the conventional moving object length measuring apparatus shown in FIGS. 2 and 3 are denoted by the same reference numerals, and detailed description of the overlapping parts will be omitted.

For example, along a transport path 2 composed of a number of roller conveyors 2a for a moving object 1 such as a long steel plate,
One rear end detector 3 and a plurality of front end detectors 4 such as 15 are provided. The distance between the detectors 3 and 4 is accurately set to a predetermined distance L.

Each of the front end detectors 4 is assigned a detector number in the transport direction from the first front end detector 4 adjacent to the rear end detector 3. Rear end detector 3 and each front end detector 4
Is constituted by an optical edge detector that detects an edge of the moving object 1 by, for example, irradiating the laser beam to the side of the transport path 2 and blocking the laser light by the moving object 1 or releasing the shading. Have been. Then, the rear end detector 3 detects the rear end 1b of the moving object 1 carried into the conveyance path 2 from the left in a non-contact manner. Each tip detector 4 detects the tip 1a of the moving object 1 carried into the transport path 2 from the left in a non-contact manner.

Further, on the side of the rear end detector 3 of the first front end detector 4, there is provided a speed detector 5 composed of, for example, a laser Doppler speedometer for accurately measuring the speed V of the moving object 1 in a non-contact manner. Have been.

The plurality of tip transfer devices 4 are connected to the transport path 2 from the left.
The leading ends 1a of the moving objects 1 to be carried in are sequentially detected. When each of the tip detectors 4 detects the tip 1a of the moving object 1, the tip detector 4 outputs a tip detection signal a assigned its own detector number to the reset terminal of the tip length counter 10 and the detection result determination unit 11
Enter

The clock oscillator 12 sends a clock signal k having a period of, for example, 1 ms to the tip length counter 10. The tip length counter 10 counts the input clock signal k. In the tip length counter 10, when the tip detection signal a is input, the count value is reset. Therefore, the tip length counter 10 detects the corresponding tip 1a in the tip detector 4 that has finally detected the tip 1a. Is measured, and the elapsed time t is detected and sent to the next tip length calculation unit 13.

The speed detector 5 sends the detected speed V of the moving object 1 to the tip length calculator 13. The tip length calculation unit 13 indicates the length of the tip portion 1c that protrudes in the transport direction from the tip detector 4 that last detected the tip 1a at the current time at a constant period of, for example, 0.1 second. ΔL is calculated by the following equation.

[0030]

(Equation 1)

The tip length calculation unit 13 sends the calculated tip length ΔL at the current time point to the current length calculation unit 14. The detection result determination unit 11 determines whether the detector number assigned to the input tip detection signal a is valid, and if the detector number is valid, converts the input tip detection signal a to the next detection number counter 15. Transfer to The detection number counter 15 counts the number N of detections of the leading end detection signal a and sends it to the fixed length calculation unit 16.

N = N + 1 The fixed length calculation unit 16 calculates a fixed length L ₁ from the position of the rear end detector 3 on the moving object 1 to the position of the front end detector 4 that finally detected the front end 1 a at the present time. I do.

L ₁ = ΣL The fixed length calculator 16 sends the calculated fixed length L ₁ to the next current length calculator 14.

The current length calculation unit 14 receives, for example, the above-described value of .0.
The current length L2 indicating the length from the position of the rear end detector 3 of the moving object 1 to the front end 1a at the current point in time at a constant period such as one _second is calculated.

L ₂ = L ₁ + ΔL The current length calculator 14 sends the calculated current length L ₂ to the detector predictor 17 and the measured value determiner 18.

The detector prediction unit 17 calculates the input current length L ₂
Then, the detector number of the tip detector 4 for detecting the tip 1a is predicted. Specifically, the number (N + 1) is obtained by adding 1 to the number of detections N used in the fixed length calculation unit 16. The detector prediction unit 17 sends the calculated detector number (N + 1) of the tip detector 4 that detects the tip 1a to the detection result determination unit 11 described above.

The detection result judging section 11 determines whether the detector number given to the next input tip detection signal a is the detector prediction section 17.
When it is confirmed that the detected tip number is (N + 1), the corresponding tip detection signal a is determined to be valid, and the input tip detection signal a is input to the next detector counter 1.
Send to 5.

If the detector number assigned to the next input tip detection signal a does not match the detector number (N + 1) predicted by the detector prediction section 17, the input tip detection signal a a is determined to be the tip detection signal a output from the tip detector 4 that is not the tip detector 4 to be originally detected due to, for example, vibration, dust, dust, or the like, and the corresponding detection signal a and the subsequent detection signals a The transfer of the detection signal a to the detector counter 15 is stopped.

Therefore, the current length calculation unit 14 stops calculating the current length L ₂ thereafter, so that an erroneous measurement result is not output to the measurement value determination unit 18. Then, the measurement object 1 further moves rightward in the figure, and the rear end 1 of the measurement object 1
When b reaches the position of the rear end detector 3, the rear end detection signal b is sent from the rear end detector 3 to the reset terminal of the detector counter 15 and the measurement value determination unit 18.

When the rear end detection signal b is input, the detector counter 15 finishes measuring the length of the measuring object 1, and
The number of detections N is reset to zero. At the time when the rear end detection signal b is output, the position of the rear end 1b of the measurement object 1 matches the installation position of the rear end detector 3, so that the current length calculation unit 14 at this time. Current length L ₂ calculated
Is the correct measurement length L ₀ of the measurement object 1.

Therefore, when the rear end detection signal b is input, the measurement value determination unit 18 determines that the current length L ₂ input at the present time is the correct measurement length L ₀ of the measurement object 1. Are displayed on the display 19.

In the thus constructed moving object length measuring apparatus, the tip (1a) of the moving object 1 moving from the left to the right in the transport path 2 in FIG. Rear end 1b after passing through the installation position of detector 4
From the installation position of the rear end detector 3 to the front end 1a of the moving object 1 moving in the transport path 2 at each time, for example, every 0.1 second until the object passes through the installation position of the rear end detector 3. current length L ₂ representing the length of is measured.

Using the calculated current length L ₂ , it is determined at what point in time the end 1 of the moving object 1 exists between the end detector 4 and the end detector 4. I can understand. Then, a tip detector 4 for detecting the tip 1 is predicted.

Therefore, the predicted tip detector 4
When the tip detector 4 other than the tip detector 4 detects the tip 1a, the tip detector 4 which is not the tip detector 4 which should be originally detected due to, for example, vibration, dust or dirt detects the tip 1a. Therefore, the operation of calculating the length of the moving object using this detection result is stopped.

Therefore, a moving object 1
Calculation of the length L ₀ can be prevented beforehand. As a result, the reliability of the entire length measuring device of the moving object can be improved. As described above, the reliability of the entire apparatus can be improved in a state where the measurement error of the length L ₀ of the moving object 1 is kept very small.

[0046]

As described above, in the apparatus for measuring the length of a moving object according to the present invention, by always measuring the position of the front end of the moving object, it is possible to predict the next end detector for detecting the front end. I have. Therefore, it is possible to prevent the length of the moving object from being calculated based on an erroneous detection result, and to significantly improve the reliability of the measurement result.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a moving object length measuring device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a conventional moving object length measuring device.

FIG. 3 is a diagram showing a principle of a length measuring operation in the conventional moving object length measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Moving object 1a ... Front end 1b ... Rear end 1c ... Front end part 2 ... Conveyance path 3 ... Rear end detector 4 ... Front end detector 5 ... Speed detector 10 ... Front end length counter 11 ... Detection result judgment part 12 ... Clock oscillator DESCRIPTION OF SYMBOLS 13 ... Tip length calculation part 14 ... Current length calculation part 15 ... Detector counter 16 ... Fixed length calculation part 17 ... Detector prediction part 18 ... Measured value determination part 19 ... Display

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Claims (2)

[Claims] 1. A rear end detector disposed at a predetermined distance from each other in a moving direction of a moving object and detecting a rear end of the moving object and a plurality of front end detectors detecting a front end of the moving object. A speed detector that detects a moving speed of the moving object, an elapsed time measuring device that measures an elapsed time since each of the leading end detecting units detects the leading end of the moving object, and the rear end detector includes: In response to the trailing edge detection of the moving object, the number of tip detectors that have already detected the tip at this time, the specified distance, the elapsed time from the tip detector that finally detected the tip, and the measured moving speed And a moving object length calculating unit that calculates the length of the moving object from the first and second end detectors, wherein the first one of the plurality of front end detectors detects the front end of the moving object. After the detection, the rear end detector moves At each time during the period until the detection of the rear end of the object, the number of the front end detectors that have already detected the front end, the specified distance and the elapsed time from the front end detector that finally detects the front end at the corresponding time. A current length calculating unit that calculates the length of the moving object at each time from the measured moving speed; and a next tip is detected based on the length of each time calculated by the current length calculating unit. A detector prediction unit for predicting the tip detector to be performed, and when a tip detector other than the tip detector predicted by the detector prediction unit next detects the tip of the moving object, the moving object length calculation unit A length measurement device for a moving object, comprising: a detection result determination unit that stops a calculation operation. 2. The moving object according to claim 1, wherein the rear-end detector and the front-end detector are optical detectors that utilize the fact that light is blocked by the presence of the moving object. Length measuring device.