GB2387970A

GB2387970A - Cross river detector apparatus

Info

Publication number: GB2387970A
Application number: GB0308308A
Authority: GB
Inventors: Ernest Roger Collinson; Philip Steven Rycroft
Original assignee: Collinson & Co Ltd E
Current assignee: Collinson & Co Ltd E
Priority date: 2002-04-10
Filing date: 2003-04-10
Publication date: 2003-10-29
Also published as: GB0308308D0

Abstract

Cross-river detector apparatus is described in which one or more elements 100, each incorporating detector means, is/are disposed, in use, across a water course. Means 2 is provided for supporting the elements 100, and the elements 100 are pivotable with respect to the support means 2. In one embodiment, the elements comprise a plurality of vertical fins disposed parallel to one another at spaced intervals across the water course. The fins are pivotable in a vertical plane. Means may be provided to restrict pivoting. In another embodiment, the elements comprise a plurality of flaps 100 that are in closely spaced side by side relation and disposed to lie adjacent the surface of the water course. Preferably the flaps are individually freely pivotable. The pivot axis is preferably disposed clear of the water. Height adjustment means may be provided for high water or flood conditions. The fin or flap elements 100 may be subject to buoyancy adjustments and their pivot position controlled via pneumatic pistons.

Description

Title: Cross River Detector Apparatus DESCRIPTION

The present invention relates to cross river detector apparatus and in particular to antenna apparatus for use with passive identification transponders but without limitation to same.

Passive identification transponders (PIT tags) have been used, both in laboratories and in the field for a number of years to study the behaviour of fish.

Use in the field has been limited in the past to relatively shallow and narrow

waters due to the low read field range of the PIT tags (typically < 1m, often <

30cm). The use of multiple "Flatbed" antennae located on the bed of a water course can give good coverage in shallow water, but have to be fastened to the bed of the river. Swim through coils up to 2m x 1m have been used but suffer from the problems of debris collection on the vertical section of the coil. Vertical fixed concrete slabs containing antennae have also been used in small waters up to a few metros in width, but this requires some considerable civil engineering to be undertaken.

It is an aim of the present invention to provide a solution which avoids the above mentioned problems and which can be used across wide stretches of moving water.

Accordingly, the present Invention provides cross rive' UlttlU! ado comprising at least one element having a leading edge and a trailing edge, the elements being disposed, in use, across a water course, each element

! embodying detector means, the apparatus further comprising means supporting the at least one element, and wherein each element is pivotally mounted with respect to said support means.

In one embodiment there are a plurality of elements, each in the form of a vertical fin which are disposed at spaced intervals across the water course. The fins are substantially planar elements and are disposed parallel to one another.

The fins are aligned with the direction of water flow. The fins are pivotable in a vertical plane. Preferably the fins are pivotable individually, but not usually freely pivotable. The water and any fish flow between the spaced fins.

The spacing of the respective fin elements is chosen to suit the read range of the PIT tags. We envisage spacing of the order of 35cm. Positioning the fin elements vertically at horizontally spaced intervals allows the detectors to be used with any desired width of river. In the event of large pieces of debris or an accumulation of small pieces of debris accumulating on the leading edge of the fin element, the increase in drag will cause the fin element to pivot.

Movement of the leading edge away from a vertical position will allow the debris to be washed away. Thus the individually pivotally movable fins become self clearing. Preferably the fin elements are suspended from the support means.

Preferably the support means extends across the river course from one bank to the other. Optionally in river supports may be provided. Where necessary, intermediate supports may be provided. Preferably the support means comprises a steel framework, preferably in the form of a support gantry. The

gantry may incorporate a walk way. This is useful for installation of the fin elements and for maintenance purposes. In one embodiment the support gantry is made up of a plurality of rods, beams or hollow tubes interconnected at spaced intervals by connector plates.

Preferably each fin element carries a mounting bracket. The pivot axis of the fin may be aligned with the leading edge of the fin or substantially adjacent thereto. Preferably the pivot axis for each fin is forwardly of its leading edge.

Preferably, it is disposed above the vertical extent of the leading edge of the fin element. A forward position of the pivot point is preferred as it compensates for the natural lifting force exerted by water flowing past the fin element but is not essential with all embodiments. However, the positioning of the pivot point may be adjustable with respect to the leading edge and vertical extent of the fin element. Additional weight (ballast) may be added to the antenna mounting bracket to "balance" the pivoting action for a particular water flow. Preferably, each fin element has a horizontal cross-section which is hydrodynamically shaped to reduce or minimize turbulence and resistance to water flow when aligned with the natural flow of water.

For the preferred application, each fin element comprises an antenna and may contain single or multiple antenna coils or ferrite based antenna coils in various configurations to minimise sensitivity to transponder orientation.

The fin elements are designed to be submersible without coming to any harm and are suitably waterproofed. The fin element may be made of wood, plastics or glass reinforced plastics or any combination thereof. The fins have a

vertical dimension that exceeds the normal depth of the water course. A transparent material would be useful to avoid the fins being used as a refuge by the fish.

The mounting bracket may have an extension that extends beyond the leading edge of the fin. Latching means may be provided between the mounting bracket and the support means. The latching means may be provided between the aforesaid extension and a part of the support means.

In a one embodiment, preferably one of the bracket or support means (preferably the latter) carries a magnet aligned to cooperate with the leading end of said extension. Where the extension is made from a nonferrous material, a ferrous coupling part is provided. The fin element will commence pivoting when the magnetic latching force is exceeded. The strength of the magnet and the distance from the pivot axis will dictate the force at which pivoting is commenced. An electro magnet may be used and/or any other latching method that allows the fin element to pivot from its normal position when released. The latch may be released at periodic intervals to prevent the build up of debris.

Once the debris has fallen away the fin will return to the latching position, (i.e. its normal vertical operating position), under the influence of gravity.

In another embodiment an actuator is provided between the fin (and/or a mounting bracket thereof) and the support means to control pivoting of the fin.

In one embodiment the actuator comprises a double acting pneumatic piston and cylinder assembly. The actuator may be controlled automatically and/or manually. Use of the actuator for moving the fin avoids the need for the pivot

axis to be set forwardly of the leading edge of the fin, although there are advantages in setting it close to or adjacent the leading edge as will be apparent hereinafter. In such an embodiment, the fins need not be pivotable individually, but arranged to be pivoted en bloc.

The fins may be disposed in a single row with a common pivot axis or in multiple rows which are staggered with each row having its own pivot axis. In each instance the pivot axis is horizontal. Having several rows is advantageous in that the effective cross-sectional area of the water is reduced to a lesser degree. When two rows are used, the antenna design may optimise tag pick up at the trailing edge of the up river fin and the leading edge of the down river fin to attain optimum tag reading efficiency.

The preferred suspension system enables multiple fin antenna to be installed in banks requiring ground support only at several metre intervals.

Means may be provided for raising and lowering the entire system to cater for flood conditions. An hydraulic or mechanical system may be provided for this purpose and it may be manually or automatically controlled.

In another embodiment, the or each element comprises a "flat bed type" antenna but positioned, in use, to have the water flow substantially underneath the or each antenna. Such an embodiment could be used for very shallow water courses or for transponders having a greater read range such as currently used with flat bed antennae.

Whilst a single antenna element may be provided, more usually a plurality of antenna elements are provided which are positioned in closely spaced side by

side relation. The or each element is pivotable about a common horizontal pivot axis. The pivot axis is preferably disposed toward the upstream (leading) edge of the elements. Preferably the pivot axis is clear of the water. Preferably the elements are freely pivotably individually.

The antenna may be constructed from wood, plastic or GRP. Preferably a transparent material is used to deter fish from sheltering under the antenna and using it as a refuge.

The means for supporting the element or elements, conveniently extends across the river from one bank to the other, although in river supports may be used, in addition or alternatively, if necessary.

The antenna preferably have positive buoyancy such that they float close to the surface. Depending on river level and their angle of inclination they may be partially submerged. The pivoting action enables the antenna to track changes in water depth within certain limits. Alternatively or additionally the support structure may be height adjustable to cater for wide variations in river levels and/or for maintenance purposes. Preferably the upstream (leading edge) of each element is clear of the water to prevent build up of debris on the leading edge. Debris would be washed under the antenna and would not build up behind the antenna to any significant degree.

The design of the support structure is such as to provide sufficient support for the antenna and may comprise a simple bar, beam or pole, or a more complex structure, for example, where wider spans are required.

In both embodiments, for preferred embodiments thereof, the water flow

direction acts to pivot the elements and has the effect of displacing any build up of debris.

The present invention will now be described further hereinafter, by way of example only, with reference to the accompanying drawings; in which: Figure 1 is a fragmentary exploded perspective view of apparatus according to one embodiment of the invention, Figure 2 is a front view of apparatus embodying the invention, Figure 3 is a side view of apparatus embodying the invention, Figure 4 is a fragmentary plan view of apparatus embodying the invention, Figure 5 is a side view of apparatus according to another embodiment, Figure 6 is a simplified perspective view of yet another embodiment of the invention, and Figure 7 is a side view of the apparatus of figure 6 in use.

Referring firstly to the drawings of figures 1 to 5, cross river antenna apparatus according to the illustrated embodiment comprises a support structure 3 and a plurality of fin elements 1. The support structure comprises three elongate tubular elements 5 extending between ground engaging supports (not illustrated) and held in spaced relation by connecting plates 7a-f. The connecting plates are apertured for passage there through of the elongate elements 5 and are secured thereto conveniently by welding. A further elongate tubular element is cut away to define portions 5a, 5b and 5c, for reasons that will be apparent from the following description.

The fin elements 1 have a cross-section that minimises water turbulence and each has a leading edge 9 and a trailing edge 11. The fins are attached to a cruciform mounting bracket having a longitudinal inverted channel 13 and a transverse inverted channel 15.

The longitudinal channel 13 is approximately twice as long as the fin which is conveniently secured to the longitudinal channel by bolts. The transverse channel 15 carries two spaced mounting elements 17 that are dimensioned to be received with rotational clearance on tubes 5, 5a, 5b or 5c as the case may be. The forward end 19 of longitudinal member 13 extends beyond the leading edge of the fin and is positioned to make cooperating engagement with a magnet or other latch element 21 extending from the support means.

Preferably, the magnet is carried on a flexible mounting.

Only two fins are shown attached to the support structure in the illustrations. One is mounted on the centre tube 5 and the other on tube fib. In figure 1 a third fin is shown displaced to illustrate more clearly the form of the connecting bracket.

The arrangement allows the fin to pivot by up to 90 from its rest position as shown in solid outline in figure 3 as denoted by arrow A. Hence the need for cutting away the tube to allow the fins mounted on the centre of the tube 5 to pivot upwardly. Pivoting in this manner allows any debris collecting on the leading edge 9 of the fin 1 to be washed away. The angle of pivoting will be dependent on the force of the water. In practice pivoting by 10-30 may be sufficient for the debris to be washed away.

To ensure that the fin remains vertical and is not pivoted by the normal force of the water flowing past the fin, the magnet 21 is arranged to cooperate with an extended end 19 of the fin mounting bracket - as seen in figure 3. The bracket is weighted to ensure an adequate contact. It will be seen that the pivot axis is disposed slightly forwardly of the lead edge 9 of the fin and above its upper extent. Most usually the fin will not be completely submerged, but the support structure is positioned to place the lower edge 10 close to the bottom of the water course.

Figure 5 is a side view of an alternative embodiment of apparatus embodying the invention. The support means is substantially as described above. Each fin has a modified mounting means 13' to accommodate a double acting pneumatic piston and cylinder assembly 51. One end of the cylinder 53 is attached to a support tube 5 and its actuating rod 55 is attached to a vertical extension 57 of the fin mounting bracket 13'. The pivot point for the fin is shown at 61 and comprises a metal band or journal. The cylinder has two ports 63, 65 and two limit switches 67, 69.

The cylinder 53 is fed by a controlled low pressure air feed at input port 63. The pressure is regulated so as to oppose the natural lifting force exerted by the water flow. When sufficient debris collects on the antenna, the cylinder rod 55 will start to be pushed in, resulting in limit switch 68 opening. This signal is then used to apply a high pressure to port 65, retracting the rod and lifting the antenna. When the antenna is lifted fully, limit switch 69 will be closed. After a short time delay, high pressure is removed from input 65 and the antenna falls to

its normal operating position under low pressure at 63. The process can be activated manually from a central control point to allow manual cleaning or periodic automatic cleaning.

The fins may be disposed in staggered rows, as best illustrated in figure 4 or in a single row (not illustrated).

The fin element incorporates antenna means, eg coils and/or ferrite rods, to facilitate their use with passive identification transponders, as is well known in the art and is not described in further detail.

Referring now to figures 6 and 7, there is illustrated an alternative embodiment of cross-river detector apparatus. In this embodiment, a plurality of antenna elements 100 comprising substantially planar elements are mounted in side by side relation for pivotal movement about a horizontal axis represented in a simplified manner by pole 102 of a support structure. The antenna elements are mounted towards their upstream (leading edge) and as will be seen from figure 7, in use, the river flow and/or their buoyancy act to displace them they are be disposed close to the surface of the water. In theory the elements could move from a vertical position to a horizontal position. In practice the amount submerged will be dependent on river level and flow. The need for positive buoyancy is optional as counterbalancing effects may be used and/or positive positional control means employed to position the antenna elements as desired to detect fish passing thereunder. The close spacing of the antenna element ensures that the whole width of the river is covered by the detectors thereof.

More elaborate multi-tube support structures may be used and the

illustrated arrangement will be understood to be a simplified structure for illustrative purposes.

The end support structure may incorporate height adjustment means, and/or means to move the structure clear of the water in high water/flood conditions as represented diagrammatically by arrows A and B in figure 6.

Claims

i CLAI MS

1. Cross-river detector apparatus comprising one or more elements having a leading edge and a trailing edge, the elements being disposed, in use, across a water course, each element embodying detector means, the ap, oaratus further comprising means supporting the at least one elemer,t, and wherein each element is pivotally mounted with respect to said support means.

2. Cross-river detector apparatus as claimed in claim 1 in which there are a plurality of elements, each in the form of a vertical fin which are disposed in parallel relation to each other at spaced intervals across the water course and in which the fins are pivotable in a vertical plane.

3. Cross-river detector apparatus as claimed in claims 1 or 2 to which the pivot axis for each fin is adjustable for position with respect to the leading edge of the fin and its height above the vertical extent of the fin.

4. Cross-river detector apparatus as claimed in claim 2 in which the pivot axis of each fin is aligned substantially with the leading edge of the fin.

5. Cross-river detector apparatus as claimed in claim 2 in which the pivot axis of each fin is forwardly of its leading edge.

6. Cross-river detector apparatus as claimed in any one of the preceding claims and including ballast to balance the fin.

7. Cross-river detector apparatus as claimed in any one of the preceding claims in which each element has a cross-section which is hydrodynamically shaped to reduce or minimise resistance to water flow.

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8. Cross-river detector apparatus as claimed in any one of the preceding claims in which the support means extends across the river from one bank to the other.

9. Cross-river detector apparatus as claimed In any one OT cram Mu; preceding in which each fin carries a mounting bracket.

10. Cross-river detector apparatus as claimed in claim 9 in which the mounting bracket incorporates latching means co-operates with the support means

1 1. FO-l IV= utLtU at anus = - a_...

latching means comprises a magnet

12. Cross-river detector apparatus latching means is an electro magnet.

13. Cross-river detector apparatus as claimed in any one of claims 1 to 9 in which actuator means is provided to control pivoting movement of the or each fin.

14. claims in which the fins are disposed in a single row.

15. Cross-river detector apparatus as claimed in any one of claims 1 to 13 in which the fins are disposed in a plurality of staggered rows.

16. Cross-river detector apparatus as claimed in claim 1 in which a single planar element spans the water course and, in use, is disposed at or adjacent the surface of the water.

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17. Cross-river detector apparatus as claimed in claim 1 in which a plurality of planar elements are provided in side by side relation extending across the water course and are disposed, in use, at or adjacent the surface of the water.

18. Cross-river detector apparatus as claimed in claims 16 or 17 in which the Q! each element is pivotable between a vertical and a horizontal position.

19. Cross-river detector apparatus as claimed in any one of claims 16 to 18 in which the or each element is buoyant.

20. Cross-river detector apparatus as claimed in any one of the preceding claims in which the support structure is height adjustable.

21. Cross-river detector apparatus constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings of figures 1 to 5 or 6 and 7.