GB2436361A

GB2436361A - Remote sensing of directional movement of objects

Info

Publication number: GB2436361A
Application number: GB0617162A
Authority: GB
Inventors: John Kyriakis
Original assignee: PROTON PRODUCTS Ltd
Current assignee: PROTON PRODUCTS Ltd
Priority date: 2006-02-24
Filing date: 2006-08-31
Publication date: 2007-09-26
Anticipated expiration: 2026-08-31
Also published as: GB0617162D0; GB2436361B; GB0603817D0

Abstract

A method and apparatus for the remote or non contact sensing or detection of movement of objects and the direction in which they move. Light from a laser diode D is focused by lens system S and directed onto object 1. Light reflected by the object 1 is collected by lens system 13 onto photocell 14. The resulting output from the photocell 14 is fed to digital processor 15 which converts the signal into a wave form (16, Fig.7). The wave form is representative of the directional movement of the object on its linear path. This wave form is transposed onto a reference grid pattern (17, Fig.7) so that the movement of the object on its linear path at any given time may be determined in relation to the observed points of interception of the gridlines on the transposed wave form (A, B, C, Fig.8). The present invention is able remotely to determine whether a product has been moved forward or in a reverse direction. This information may be introduced into an optical/laser Doppler length measuring system. The invention is applicable to the manufacture of elongated products such as wires, cables, rolls and sheeting.

Description

Remote Sensini of Directional Movement of Objects

Field of the invention

The present invention relates to a method and apparatus fbr the remote or non-contact sensing or detection of movement of various objects and the direction in which they move.

In particular, the invention is applicable to the manufacture of elongated products which are produced in a linear fashion, such as wires, cables, paper rolls, plastic sheeting, floor covering materials, membranes, aluminium rolls and the like.

Backaround of the invention

amount of material is measured and then cut to length as required by the purchaser.

The measurement of the produced material has been traditionally effected by contact means which requires the use of a wheel niking contact with the produced material, the wheel operating a mechanical length counter or, in a more advanced version, an electronic control system.

This method is still used in a number of manufacturing outlets, but it does suffer from accuracy problems due to mechanical wear of the pulley making contact with the product possible slippage due to jumping of the pulley, etc. Other contact methods have been used, including a multiplicity of pulleys, operating through a mechanical gear box in an effort of overeome the jumping' eflbct and also a caterpillar-type unit utilising contact plastic or rubber belts in order to increase the contact between the measuring devise and the product being produced.

More advanced non-contact measuring length systems are in existence, namely laser doppler devices, as well as optical pattern recognition instruments, all of which have an advantage of a non-contact measurement of linearly produced materials, provided of course the interpretation of the optical results and the spectral analysis of the signals has been perfonned accurately in the electronic circuits that translate the light vaLues correctly.

These optical non-contact systems operate on the principle of applying a focused beam of light, usually from a laser source, onto the moving product and then examining the reflected or refracted light emanating from the moving product These systems have obvious advantages over any contact methods as they do not rely any mechanical contact, there is not obvious mechanical wear and no jumping' experienced in the previously described mechanical methods.

However, the optical methods of length measurement are generally unable to determine the direction in which the products are moving which is a feature that the contact methods can perform.

The present invention overcomes this disadvantage and can determine whether the product is being moved forward or being moved in a reverse direction and thus making the optical non-contact method to perform in an identical fashion to the traditional contact method.

Summary of the inveutlon

According to one aspect of the invention there is provided a method of detecting the movements of an object on a pre-determined linear path of travel comprising directing a beam of light onto the object, measuring the light reflected by the object from the beam, producing a waveform from the beam representative of the directional movements of the object on its linear path, transposing the waveform on a reference grid pattern, and determining the movement of the object on said pre- determined Linear path at any given time in relation to the observed points of interception of the grid lines on the transposed waveform.

Preferred features of the invention will be described hereunder in relation to the accompanying drawings Brief deerlDtion of the drawinas The invention will now be described by way of example with reference the accompanying drawings wherein; Figure 1 illustrates a contact method for measuring a certain amount of moving strip material to be cut according to the prior art; Figure 2 illustrates a second prior art contact measuring system for cutting moving material of a pre-determined length; Figure 3 is a further contact measuring system in accordance with the prior art; Figure 4 illustrates a non-contact measuring length system in accordance with thepriorart; Figures 5 and 6 illustrate a non-contact optical length measuring system for moving stripped material in accordance with the invention; Figure 7 illustrates the transposition of the waveform replicating a beam of light directed onto the strip material to be cut, onto a reference grid pattern; and Figure 8 illustrates the detennination of the movements of the strip material using the waveform in relation to the reference grid pattern.

Preferred embodiments With reference to Figure 1 a contact method for length measurement of a strip of material (1) moving in a pre-determined path of travel indicated by an arrow (2) is shown. Contact with the moving product (I) is made by means of a wheel (3) coupled to a mechanical counter (4).

As referred to earlier, inaccuracy problems arise with this arrangement due to mechanical wear of the wheel (3) making contact with the product (1) and also slippage contact with the product (1).

A multiplicity of contact wheels or pulleys (5) have been employed as shown in effort to overcome the jumping effect experienced with the Figure 1 arrangement.

S In Figure 3 a further variant according to the prior art is illustrated, this utilising a caterpillar-type unit (8) having contact plastics or rubbers belts (9) used in order to increase the contact between the measuring device and the moving strip product (1).

More advanced length measuring systems of the non-contact type have been deployed namely laser doppler devices (10) shown in Figure 4, as well as optical pattern recognition instruments. The laser doppler device (10) operates on the principle of taking measurements from a reflected beam of laser light (11) directed onto the product (I) which are indicative of the directional movement of the strip (2).

All of these non-contact systems have the advantage that they avoid contact problems of mechanical and moving parts. Their reliability of course depends on correct interpretation of the optical results and the accuracy of the processing methods employed to determine those optical results.

In particular the optical methods of length measurement are unable to take account of the factthatthe material may c e its linearpath of lby moving theleft or the right or actually stopping and reversing, so that the accuracy of the length of material finally cut to chosen lengths is compromised.

Figures 5 and 6 illustrate the measuring system according to the invention and this comprises a laser optical directional system (12) for directing a beam of light onto the moving strip material (1) as shown in Figure 5.

The laser optical directional system comprises a laser diode (D) and a lens system (S) as illustrated in Figure 6.

Also illustrated in Figure 6 are the component parts of the system for analysing the reflected beam from the strip material (1) and these comprise a lens system (13), a photocell (14) and a directional output processor (15) for analysing the output wavelength of reflected light.

The processing of the output wave form of a reflected light is illustrated with referencetoFigures7and8.

The resulting electrical output from the photocell (14) is fed into the digital processor (15) which converts the signal from the photocell (14) into a wavefbrm (16) as shown in Figure 7.

The waveform (16) is placed onto a reference grid (17) of vertical lines of which XX is a typical example.

The vertical lines are scanned in the processor (15) in order to determine the position of the waveform.

The position of the waveform (16) in relation to the scanned vertical and lines (17) namely the intersection of the waveform with those vertical lines, is illustrated in Figure 8.

Thus, when the product (1) is stationary, the Point B, (see Figure 8), remains fixed in the position of the vertical line XX. If the product moves to the right of the grid, that is a forward direction, the waveform will intercept the vertical line XX at point C. Should the product (1) move to the left of the grid (reverse) the waveform will intercept the vertical line XX at position A. In order to enhance the accuracy of the system, all the vertical lines similar to XX are scanned by the processor and the positions of the intersections of the waveform with the vertical line such as A, B and C previously described are stored in the processor memory (15).

The processor (15) now has the following information. If the product (1) has stopped, the processor (15) will output a signal indicating that position B has been obtained.

Therefore the product (2) is stationary.

If the product (2) moves forward, the processor (15) will identify point C and therefore output a signal indicating that the product (1) has moved in a forward duection.

If the product (1) has moved in a reverse direction, the processor (1 5) will identify that point A has been reached and will output a signal to indicate that the product (1) has moved in a reverse direction.

The invention thus provides a system which can give out three types of information, i.e. product (1) moving forward, product (1) moving in reverse or product (1) stationary.

This information may be introduced into an optical/laser doppler length measuring system and this will complete the process of replicating the contract measuring wheel of the prior art but without making physical contact and also from a remote position.

The description given above may be summarised as follows: 1. Method and apparatus for determining the direction of movement of an object.

2. Method and apparatus for determining the direction of movement of an object by non-contact means.

3. Method and apparatus for remote or non-contact sensing the positional state of an object which is either at rest or moving in a linear fashion in one direction and/or in a reverse direction.

4. Method and apparatus in which a laser focused beam is trained onto an object which is being produced in a linear fashion and the reflected or refracted light is used to determine whether the object is at rest or moving forward or in a reverse direction.

5. Method and apparatus in which a light source is fbcused onto a product which is produced in an elongated linear fashion and the then ensuing reflected or refracted light is treated in suchaway sothatitcanbesej,de di positional status of the product indicating whether the product has stopped, moving forward or in a reverse fashion and this information may then be introduced into a non-contact lemote laser doppler or other optical length measuring system, thus indicating the speed or length of the product whether this is in a forward or reverse direction.

Claims

S

CLAIMS

1. A method of detecting the movements of an object on a pie-determined linear path of travel comprising directing a beam of light onto the object, measuring the light reflected by the object from the beam, producing a waveform from the beam representative of the directional movements of the object on its linear path, transposing the waveform on a reference grid pattern, and determining the movement of the object on said pie-determined linear path at any given time in relation to the observed points of interception of the grid lines on the transposed waveform.

2. A method as claimed in claim I including providing output signals representative of the position of the waveform in relation to the re1rence grid pattern, and feeding said signals to an optical length measuring device to correct for inaccuracy in the results obtained therefrom.

3. Apparatus for detecting the movements of an object on a pie-determined linear path of travel comprising means for directing a beam of light onto the object, means for measuring the light reflected by the object from the beam, output means for producing a waveform representative of the directional movements of the object on its linear path determined from said measuring means, means for transposing the waveform on a reference grid pattern, and means for determining the movement of the object on said pie-determined linear path at any given time in relation to the observed points of intersection of the grid lines on the transposed waveform.

4. Apparatus as claimed in claim 3 wherein said means for directing a beam of light onto the object is a laser diode.

5. Apparatus as claimed in claim 3 wherein said measuring means is a lens which collects the light reflected from the object onto a photocell.

6. Apparatus as claimed in claim 3 wherein the output of the photocell is fed into a digital processor for converting the signal from the photocell into a representative waveform.

7. Apparatus as claimed in 6 wherein means are provided in the processor for transposing said waveform onto a reference grid, and means in the processor for scanning the vertical grid lines to determine the position of the waveform relative thereto.

8. Apparatus as claimed in claim 7 wherein said scanning of the waveform in relation to the referenced grid lines produces an indication of the stationary, backward and forward movements of said object on its path of travel.

9. Apparatus as claimed in claim 8 wherein an optical/laser doppler length measuring system is employed to process information fed thereto by said processor accurately to determine a chosen cut length of said object.

10. A method of detecting the movements of an object on a pre-determined linear path of travel comprising directing a beam of light onto the object, collecting the light reflected by the object from the beam, producing a reference wave pattern from the reflected light and comparing the variations in the wave pattern against a positional reference marker thereby to determine the movements of the object on its linear path of travel.

pppv Amendments to the claims

CLAIMS

1. A method of detecting the movements of an object on a pre-determined linear path of travel comprising directing a beam of light onto the object, measuring the light reflected by the object from the beam, producing a waveform from the beam representative of the directional movements of the object on its linear path, transposing the waveform on a reference grid pattern, and determining the movement of the object on said pre-determined linear path at any given time in relation to the observed points of interception of the grid lines on the transposed waveform.

2. A method as claimed in claim 1 including providing output signals representative of the position of the waveform in relation to the reference grid pattern, and feeding said signals to an optical length measuring device to correct for inaccuracy in the results obtained therefrom.

3. Apparatus for detecting the movements of an object on a pre-determined linear path of travel comprising means for directing a beam of light onto the object, means for measuring the light reflected by the object from the beam, output means for producing a waveform representative of the directional movements of the object on its linear path determined from said measuring means, means for transposing the waveform on a reference grid pattern, and means for determining the movement of the object on said pre-detennined linear path at any given time in relation to the observed points of intersection of the grid lines on the transposed waveform.

4. Apparatus as claimed in claim 3 wherein said means for directing a beam of light onto the object is alaserdiode. * **

*..30 5. Apparatus as claimed in claim 3 wherein said measuring means is a lens which collects the light reflected from the object onto a photocell. * ** S. S S... 5.555 * S

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6. Apparatus as claimed in claim 3 wherein the output of the photocell is fed into a digital processor for converting the signal from the photocell into a representative wavefbrm.

7. Apparatus as claimed in 6 wherein means are provided in the processor for transposing said waveform onto a reference grid, and means in the processor for scanning the vertical grid lines to detennine the position of the waveform relative thereto.

8. Apparatus as claimed in claim 7 wherein said scanning of the waveform in relation to the referenced grid lines produces an indication of the stationary, backward and forward movements of said object on its path of travel.

9. Apparatus as claimed in claimS wherein an optical/laser doppler length measuring system is employed to process information fed thereto by said processor accurately to determine a chosen cut length of said object. * S.. S... * . *.. * .5 * S * .. * *S * * *...

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