DE102005036164A1 - Contactless detection of objects on transport carrier involves comparing result of mathematical operation, performed on measured distance between objects on transport carrier, with predetermined value to activate or deactivate output signal - Google Patents

Abstract

The method involves using optical distance sensor (16) for measuring at least two temporal distances of objects (14) on transport carrier (15), and performing mathematical operation on the obtained temporal distance measurement values. The result of the mathematical operation is compared with a predetermined limit value for activating or deactivating an output signal. The mathematical operation is performed to determine the difference between the two distance signals, quotient of the distance signals, combination of the difference and quotient, or statistical function of the distance signals. An independent claim is included for the contactless detecting device.

Description

The The invention relates to an apparatus and a method for detection of objects, which are located on a carrier moved along a transport direction. In particular, this carrier varies in its distance to the detection unit and the objects to be detected small.

From the patent DE10142161 a method is known which generates an object detection signal with the aid of 2 receiving units in an optoelectronic sensor. It records the object with a receiver and the object with a second receiver and forms, for example, the difference between the two signals. Thus, even at different carrier distances with the help of the difference, the object can be detected.

The Method has the disadvantage that in general the two receivers fixed interconnected and thus the difference to be detected within a limited Area must occur. In addition, the method has the disadvantage that it is difficult with very small objects becomes, the carrier and to securely capture the object with one receiver each, since the detection locations are close to each other and the signals u.U. no longer unique to the wearer or the background.

a Another disadvantage arises when the article has a slope and thus between the two places observed by the receivers only small differences arise, then the subject is not captured.

Other Methods set one or more individual measuring sensors for the wearer and the object and process their information in a parent Control. Their disadvantage is that one for the sensors devices for data acquisition benötig and this data in a parent Control must be processed.

The The object of the invention is articles on a in the transport direction moving carrier safe non-contact capture; even if the objects are small and the wearer in his Distance to the sensor fluctuates.

Of the Distance of the carrier can order a larger amount fluctuate as the amount of height of the Object about the carrier.

Instead of a carrier can also be the presence of an increase or depression within of the moving object. Then one part corresponds of the object to the wearer.

In other cases the object can stand still and a sensor will over the Subject to this or part of the object capture

at the objects it can be isolated objects but also a shingled stream, to count its elements are. Its height can be much stronger vary as the height of a single element of the scale flow.

The objects can have steep flanks, but also rise flat.

Solution according to the invention

These Task is solved by a method and an apparatus having the features of the corresponding ones independent Claims.

The Task is solved by that preferably with an optical distance sensor, but also with other distance sensors, continuously at intervals (intervals) the distance from the sensor to the carrier or object is detected. The sensor stores the successive ones Distances. He accounts for these distances, he forms e.g. the difference, and compares it to a limit. If an object moves into the measuring range, it becomes a measurement in front of the article e.g. on the carrier and a subsequent measurement give on the object. In this case, the difference is almost equal to the height of the object. The result is largely independent of distance change of the carrier.

Of the The object can be detected so safely.

The time intervals the measurements can for different Tasks be different.

Of the Time interval of the measurements (sampling interval) is so too choose, that within the interval, the change of the base distance decreases is the height to be detected of the object.

The Advantages of the invention solution then lie that fluctuations in the distance of the carrier through the difference in the sensor can be eliminated. He gives a digital Switching signal off and makes the processing of the distance data through a machine control superfluous.

If an object has an oblique and not a vertical side, then the sampling interval can be so be chosen that certainly one measurement point is on the support and the other sufficiently high on the slope to capture this object.

By suitable choice of sampling intervals and e.g. a thin laser beam of an optical triangulation sensor can also be very small objects on a carrier be recorded.

By appropriate choice of sampling intervals can detect skews of the objects themselves become.

In a preferred embodiment According to the invention, the limit value can be applied to the sensor by means of a corresponding teach-in method be communicated. The sampling interval may be at the sensor by appropriate input methods be set.

In cases where a continuous recording and checking the difference does not make sense it is (for example, other objects are in the detection area) makes sense to specify the sampling intervals by a controller from the outside.

In further cases It may be useful, the first by electrical signal from the outside Value to capture and then continuously the difference to this Value and compare with the limit difference.

1 shows an overview of the method and the device.

2 shows the timing of the detection of the object.

The method and the device comprises a distance sensor ( 1 ), in this case an optical triangulation sensor. In it is an internal clock ( 3 ) for triggering the distance measurement and a computing and storage unit ( 4 ).

For further tasks, the sensor has a connection for an external clock ( 2 ).

The items to be recorded ( 5 ) are moving on a carrier ( 6 ) across the measuring direction of the sensor. When detecting an object, a switching output ( 7 ) to be activated.

The clocked sample is in 2 by ( 8th ) symbolizes. In 2 the changes of height ( 9 ) and detected difference ( 10 ) especially when running ( 11 ) of objects.

With 12 and 13 possible limits are shown that must be exceeded or fallen short of.

With every bar ( 8th ), the currently measured distance to an object or carrier is stored and subtracted from the last measured and stored distance.

The Difference changes therefore only with the clock.

at continuous reduction of the distance to the sensor, thus enlarging the Height, is she is taller than at enlargement of the Distance.

Of the Value is compared with the stored difference and the switching output operated according to the result.

The location of the limit value for the detection of the object may be such that the beginning of the object is determined ( 12 ).

If the limit is set to activate when the distance increases ( 13 ), then the end of the Gegentandes is determined.

In other cases it may make sense the sampling intervals by a controller specify from the outside or by control signal to capture the first value and then continuously to form the difference to that value and to compare with the limit difference.

1

distance sensor

2

external timer

3

internal timer

4

storage unit

5

To capturing item

6

Carrier of the article

7

switching output

8th

clock schematically

9

height signal

10

difference signal

11

influence of the object on the altitude signal

12

Border, detects the beginning of the object

13

Border, detects the end of the object

14

To capturing item

15

Carrier of the article

16

optical distance sensor

17

Seichereinheit

18

clock

19

schematic Signal curve of the difference

Claims (13)

Method that detects the presence of an object on a support and in the form of a counter characterized by the following features: • by means of a single distance sensor, at least two distance measurements are carried out at a time interval • with the results of which a mathematical operation is performed • the result value of said mathematical operation is compared with a previously determined limit, resulting in an activation or deactivation of an output signal. Method according to claim 1, characterized in that that said mathematical operation is the difference of the two Distance signals is. Method according to claim 1, characterized in that that said mathematical operation is the quotient of the two Distance signals is. Method according to claim 1, characterized in that that said mathematical operation is a combination of difference and quotient of the two distance signals. Method according to claim 1, characterized in that that said mathematical operation is a statistical function two or more distance signals. Method according to one of the preceding claims, characterized characterized in that the distance measurements periodically by a be triggered in the distance sensor timer. Method according to Claims 1 to 5, characterized that the distance measurements are triggered by an external signal. Method according to one of the preceding claims, characterized characterized in that the first distance measurement by an external Signal triggered and the further distance measurements are periodically repeated by the sensor and the difference is always formed for the first distance measurement. Method according to one of the preceding claims, characterized characterized in that the limit difference is fixed. Method according to Claims 1 to 8, characterized that the limit difference predetermine the sensor by a learning procedure becomes. Device according to one of the preceding claims, characterized characterized in that an optical distance sensor detects the distances. Device according to claims 1-10, characterized in that that an ultrasonic distance sensor detects the distances. Device according to claims 1-10, characterized in that that an inductive distance sensor detects the distances.