Knee link flail (KLF) system

Abstract

A knee link flail system for neutralization of landmines consisting of a rotatable shaft mounted on a carriage with flat structures attached perpendicular to the shaft at predetermined intervals. A plurality of first legs are connected to outer edges of the flat structures via first rotatable connections. A plurality of second legs, each being connected to an outer end of an associated first leg via a rotatable connection. A hammer mass is attached to an outer end of each second leg that impacts against a soil's surface upon rotation of the rotatable shaft.

Description

This claims benefit of PROVISIONAL APPLICATION Ser. No. 60/541,062 filed on 3 Feb. 2004.

FIELD OF THE INVENTION

The present invention is related to a flail system to detonate mines buried in the soil and, in particular, to a flail designed to generally provide a more uniform impact on the soil's surface to detonate land mines.

BACKGROUND OF THE INVENTION

Since 1945, it is estimated 100,+/−10 million landmines have been laid in 64 countries and now the only continents free of them are Australia, North America and Antarctica. Land mines kill or maim about 26000 people every year. The existing methods of finding, removing, and destroying landmines are grossly inadequate, slow, expensive, and unacceptable. Globally, several million people are waiting to return to their homes, however, before economic reconstruction and rehabilitation of the people can commence it is essential that buried landmines be cleared and neutralized.

Current practices of mine clearing and neutralization; centers on manual methods, using metal detectors and prodders, a slow, labour intensive, high risk, and expensive process. Some heavy earth moving, and earth processing equipment are being experimented with but this often results in total destruction of the vegetation covering the ground and raises environmental questions. Some chain link flail systems are used at demining sites from time to time, and changes made using trial and error methods, Professional, scientific, and comprehensive methodology is very rarely followed, therefore the results are seldom reported to professional audience for review and comment.

Most buried landmines today are pressure activated and have almost no metal parts, the exception being the detonator needle and distinguishing it from the metallic debris of a minefield is expensive. The soil in most minefields is contaminated with significant quantities of shrapnel, metal scrap and cartridge cases, leading up to 100 to a 1000 false alarms for each mine detected. However, each alarm must be carefully investigated using a prodder. In these conditions hundreds of bits of metal are dug up for every mine detected, leading to operator fatigue and increased risk.

Several sensor technologies are in development, but no single sensor is reliable enough to confirm a mine with high degree of reliability in every situation. Consideration is being given to combining a number of sensor technologies to detect mines, however, this will add to the cost and complexity of the product. How acceptable, affordable, and useful this product will be (to less developed and poor countries) is a debatable point.

Mechanised chain link flail (CLF) systems have been often proposed to speed up the demining process, to reduce the cost, and the risk associated with the neutralization of buried mines. In recent years several prototypes of flail systems have been fabricated for marketing to humanitarian agencies the world over. Independent field trials on typical systems by Canadian Forces personnel have revealed that the performance is less than satisfactory, and do not meet the needs of the international demining community. Landmines are generally buried within 10 cm of the ground surface. The United Nations requirement for mine clearance is 99.6% clearance to a ground depth of 20 cm.

Popular anti-mine flail systems currently available primarily consist of a number of chains evenly spaced and connected at one end to a common horizontal power shaft. The other end of each chain is connected to a weight called a hammer. The shape and size of the hammer vary widely from one system to another. Some hammers are shaped to clear the vegetation, some are shaped to chisel the ground, cut and break up mines, some are shaped to transmit on impact a stress field to trigger the buried mine, and some are expected to do more than one of the above. With the result that the primary objective to trigger and detonate buried mines is not achieved in most cases and marginally in other cases. Some examples of hammer used in field trials are a cubicle hammer, disc, sphere, and foot that is similar to a cubicle hammer but with an enlarged lower surface. The popularity of flails over other demining mechanical systems such as rollers rakes and soil mills are that they are simpler, lightweight, low maintenance and low cost systems.

The adverse effects attributed to chain link flails are:

• • They create and move overburden, which then covers mines so deep that they cannot be detected later by using the available metal detectors;
  • They leave ridges large enough for mines to be missed between the ridges;
  • Only a small percentage of pressure activated mines are triggered and neutralized less than 50%, the rest are scattered, some still active, some in one piece, some in pieces everywhere, even into areas that have been painstakingly cleared compounding the problem.

The hammer and sphere shapes, for instance attempt to detonate a mine by importing energy into the ground to trigger the fuze. The foot shape tries to chisel the ground thus exposing the mine.

The adverse effects attributed to a chain link flail, is a direct result of the degree of freedom provided by a chain link. When a flail rotating at high speed is lowered and the weights start impacting the ground, a degree of instability is introduced in the flailing process. This instability is enhanced when the weight breaks through the ground surface and starts to plough the ground. The weight geometry determines the extent of surface indentation and the depth to which the ground surface is penetrated by the weight on impact. A weight with a geometry that provides it with sharp edges will accentuate the penetration of the weight into the ground and the adverse flail effects. As the chain linked weight ploughs through the ground that is non-homogeneous the weight surface is subjected to randomly changing force distribution. High speed filming of flail ground interaction has revealed that a chain linked weight goes through numerous and random twists and turns, pull-in and push-out actions, and sways side to side. These actions create valleys and ridges, and result in uneven ground overage with missed areas, and missed mines, during the flailing process, and leaving the ground surface in a chaotic state.

SUMMARY OF THE PRESENT INVENTION

It is an object of the present invention to design a knee link flail with an objective to trigger and neutralize a pressure activated mine where buried, with the least amount of overall ground disturbance.

The Knee Link Flail (KLF) according to the present invention is an effective channel for the transfer of power from the power shaft to a hammer mass. It ensures measured, even, systematic normal force penetration and ground coverage, such that the ground surface is evenly covered and no zones are skipped.

A knee link flail system according to one embodiment of the invention comprises a rotatable shaft mounted horizontally on a carriage with a plurality of flat structures attached to and being perpendicular to the rotatable shaft which structures are spaced at predetermined intervals along the rotatable shaft, a plurality of first legs connected to outer edges of said flat structures via first rotatable connections, a plurality of second legs that are each connected to an outer end of an associated first leg via a rotatable connection, a hammer mass being attached to outer ends of each second leg that impacts against a soil's surface upon rotation of said rotatable shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the present invention will now be described in more detail with reference to the accompanying drawings, wherein:

FIG. 1a is a side view of a typical knee link flail assembly according to the present invention.

FIG. 1b is a front view of FIG. 1b with hammers added to ends of the flails.

FIGS. 2a, 2b and 2c are perspective views of hammer types used with the flail assembly according to the present invention.

FIGS. 3a, 3b, 3c and 3d illustrate soil profiles obtained with a 445 mm knee link flail having 1:1 and 1:05 link ratios at different soil compaction rates and different hammer shapes.

FIGS. 4a, 4b, 4c and 4d illustrate soil profiles obtained with a 345 mm knee link flail having 1:1 and 1:05 link ratios at different soil compactions rates and different hammer shapes.

FIGS. 5a, 5b, 5c and 5d illustrate soil profiles obtained with a 345 mm and 445 mm chain link flail at different soil compactions rates and different hammer shapes (cubicle and sphere).

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The present invention is related to a flail system to detonate mines buried in the soil and, in particular, to a flail designed to generally provide a more uniform impact on the soil's surface to detonate land mines.

Since 1945, it is estimated 100,+/−10 million landmines have been laid in 64 countries and now the only continents free of them are Australia, North America and Antarctica. Land mines kill or maim about 26000 people every year. The existing methods of finding, removing, and destroying landmines are grossly inadequate, slow, expensive, and unacceptable. Globally, several million people are waiting to return to their homes, however, before economic reconstruction and rehabilitation of the people can commence it is essential that buried landmines be cleared and neutralized.

Current practices of mine clearing and neutralization; centers on manual methods, using metal detectors and prodders, a slow, labour intensive, high risk, and expensive process. Some heavy earth moving, and earth processing equipment are being experimented with but this often results in total destruction of the vegetation covering the ground and raises environmental questions. Some chain link flail systems are used at demining sites from time to time, with changes being made using trial and error methods. Professional, scientific, and comprehensive methodology is very rarely followed, therefore the results are seldom reported to professional audience for review and comment.

Most buried landmines today are pressure activated and have almost no metal parts, the exception being the detonator needle but distinguishing it from the metallic debris of a minefield is expensive. The soil in most minefields is contaminated with significant quantities of shrapnel, metal scrap and cartridge cases, leading up to 100 to a 1000 false alarms for each mine detected. However, each alarm must be carefully investigated using a prodder. In these conditions hundreds of bits of metal are dug up for every mine detected, leading to operator fatigue and increased risk.

Several sensor technologies are in development, but no single sensor is reliable enough to confirm a mine with high degree of reliability in every situation. Consideration is being given to combining a number of sensor technologies to detect mines, however, this will add to the cost and complexity of the product. How acceptable, affordable, and useful this product will be (to less developed and poor countries) is a debatable point.

Mechanised chain link flail (CLF) systems have been often proposed to speed up the demining process, to reduce the cost, and the risk associated with the neutralization of buried mines. In recent years several prototypes of flail systems have been fabricated for marketing to humanitarian agencies the world over. Independent field trials on typical systems by Canadian Forces personnel have revealed that CLF performance is less than satisfactory, and do not meet the needs of the international demining community. Landmines are generally buried within 10 cm of the ground surface. The United Nations requirement for mine clearance is 99.6% clearance to a ground depth of 20 cm.

Popular anti-mine flail systems currently available primarily consist of a number of chains evenly spaced and connected at one end to a common horizontal power shaft. The other end of each chain is connected to a weight called a hammer. The shape and size of the hammer does vary widely from one system to another. Some hammers are shaped to clear the vegetation, some are shaped to chisel the ground, cut and break up mines, some are shaped to transmit on impact a stress field to trigger the buried mine, and some are expected to do more than one of the above. This results in that the primary objective to trigger and detonate buried mines is not achieved in most cases and marginally in other cases. Some examples of hammer used in field trials are a cubicle hammer, disc, sphere and foot that is similar to a cubicle hammer but with an enlarged lower surface. The popularity of flails over other demining mechanical systems such as rollers rakes and soil mills are that they are simpler, lightweight, low maintenance and low cost systems.

The adverse effects attributed to chain link flails are:

• • They create and move overburden, which then covers mines so deep that they cannot be detected later by using the available metal detectors;
  • They leave ridges large enough for mines to be missed between the ridges;
  • Only a small percentage of pressure activated mines are triggered and neutralized less than 50%, the rest are scattered, some still active, some in one piece, some in pieces everywhere, even into areas that have been painstakingly cleared compounding the problem.

The hammer and sphere shapes, for instance attempt to detonate a mine by importing energy into the ground to trigger the fuze. The foot shape tries to chisel the ground thus exposing the mine.

The adverse effects attributed to a chain link flail, is a direct result of the degree of freedom provided by a chain link. When a flail rotating at high speed is lowered and the hammer start impacting the ground, a degree of instability is introduced in the flailing process. This instability is enhanced when the hammer breaks through the ground surface and starts to plough the ground. The weight geometry determines the extent of surface indentation and the depth to which the ground surface is penetrated by the hammer on impact. A hammer with a geometry that provides it with sharp edges will accentuate the penetration into the ground and the adverse flail effects. As the hammer ploughs through the ground that is non-homogeneous the hammer is subjected to randomly changing force distribution. High speed filming of flail ground interaction has revealed that a chain linked flail goes through numerous and random twists and turns, pull-in and push-out actions, and sways side to side. These actions create valleys and ridges, and result in uneven ground overage with missed areas, and missed mines, during the flailing process, and leaving the ground surface in a chaotic state.

A knee link flail mine neutralizing device according to the present invention is illustrated in the side view of FIG. 1a and front view of FIG. 1b. It consists of a number of discs 1 spaced at intervals along the length and attached to a rotatable shaft 3 which is horizontally mounted on a carriage. The disc 1 can have various shapes, such as triangular, or other flats structures attached perpendicular to shaft 3. Legs 4, 4′ and 4″ (three are shown in FIG. 1a but that number can be varied) are connected to disc 1 via a rotatable connection 2, 2″ and 2′″ which allows for rotation of the legs as the shaft 3 is rotating. The outer ends of the legs 4′, 4, 4″ are connected to an associated second outer legs 5, 5′, 5″ via a rotatable connection 7, 7′, 7″ which allows for rotation of the second legs. The outer ends of the second outer legs are connected to a hammer type mass 10, 10′, 10″ via connections 6, 6′, 6″ as best illustrated in FIG. 1b. The length of legs 4, 4′, 4″ and 5, 5′, and 5″ can be varied to provide different ratios between lengths of the legs.

FIGS. 2a, 2b and 2c illustrate different types of masses that may be attached to outer ends of the second outer legs. FIG. 2a illustrates roller masses 10 that are attached to outer arms (see FIG. 1b also). FIG. 2b illustrates a cubicle mass 12 that is connected to the outer legs 5, 5′, 5″ via an intermediate link 13 and via a rotatable connection 14 at one end of link 13 rather that rollers 10 as in FIG. 2a. FIG. 2c illustrates a spherical mass 15 that is connected to outer legs 5, 5′ and 5″ via a rotatable connection 14′ at one end of link 13′ rather than the cubicle mass 12 as illustrated in FIG. 2b.

Experiments were carried out in the soil bin facilities of the department of Agricultural and Bioresource Engineering of the University of Saskatchewan. The Knee Link Flail (KLF) and Chain Link Flail (CLF) were tested in soil using the following parameters:

A 3 hp electric motor was used to rotate shaft 3 via a chain and sprocet mechanism. An inverter was used to change the frequency and control the shaft's speed. The shaft was mounted on a carriage that could be pushed over a minefield. The rotating shaft could be raised or lowered to vary the impact of the hammers on the surface of the soil.

Hammer Parameters:

• • Two flail types (KLF and CLF)
  • Three hammer shapes (Roller, Spherical and Cube)
  • Two flail lengths (345 mm and 345 mm)
  • Two KLF link length ratios (1:1 and 1:05)
  • One hammer strike/inch
  • One hammer height (241 mm)

Soil Parameters:

• • One soil moisture level (13-14%)
  • Two Compaction levels (medium and high)

FIG. 3a show graphs of soil profiles obtained in experiments using a 445 mm KNL apparatus with a 1:05 link ratio and medium compaction wherein ▪—is a graph of a soil profile obtained with a cubicle mass, ●—is a graph of the soil profile obtained with a spherical mass and ▬—is a graph of the soil profile obtained with a roller mass.

FIG. 3b show graphs of soil profiles obtained in experiments using a 445 mm KNL apparatus with 1:05 link ratio and high compaction wherein ▪—is a graph of the soil profile obtained with a cubicle mass and ●—is a graph of the soil profile obtained with a spherical mass and ▬—is a graph of the soil profile obtained with a roller mass.

FIG. 3c shows graphs of soil profiles obtained in experiments using a 445 mm KNL apparatus with a 1:1 link ratio and medium compaction wherein ▪—is a graph of the soil profile obtained with a cubicle mass, ●—is a graph of the soil profile obtained with a spherical mass and ▬—is a graph of the soil profile obtained with a roller mass.

FIG. 3d shows graphs of soil profiles obtained in experiments using a 445 mm KNL device with a 1:1 knee link ratio and high compaction wherein ▪—is a graph of the soil profile obtained with a cubicle mass, ●—is a graph of the soil profile obtained with a spherical mass and ▬—is a graph of the soil profile obtained with a roller mass.

FIG. 4a shows graphs of soil profiles obtained in experiments using a 345 mm KLF apparatus with 1:05 KNL ratio and medium compaction wherein ▪—is a graph of the soil profile obtained with a cubicle mass, ●—is a graph of the soil profile obtained with a spherical mass and ▬—is a graph of the soil profile obtained with a roller mass.

FIG. 4b shows graphs of soil profiles obtained in experiments using a 345 mm KNL apparatus with a 1:05 knee link ratio and high compaction wherein ▪—is a graph of the soil profile obtained with a cubicle mass, ●—is a graph of the soil profile obtained with a spherical mass and ▬—is a graph of the soil profile obtained with a roller mass.

FIG. 4c show graphs of soil profiles obtained in experiments with a 345 mm KNL apparatus with a 1:1 link ratio and medium compaction wherein ▪—is a graph of the soil profile obtained with a cubicle mass, ●—is a graph of the soil profile obtained with a spherical mass and ▬—is a graph of the soil profile obtained with a roller mass.

FIG. 4d show graphs of soil profiles obtained in experiments with a 345 mm KNL apparatus with a 1:1 link ratio and high compaction wherein ▪—is a graph of the soil profile obtained with a cubicle mass, ●—is a graph of the soil profile obtained with a spherical mass and ▬—is a graph of the soil profile obtained with a roller mass.

FIG. 5a shows graphs of soil profiles obtained in experiments with a 345 mm CLF apparatus and medium compaction wherein ▪—is a graph obtained with a cubicle hammer and ●—is a graph obtained with a ball.

FIG. 5b shows graphs of soil profiles obtained in experiments with a 345 mm CLF apparatus and high compaction wherein ▪—is a graph obtained with a cubicle hammer and ●—is a graph obtained with a ball.

FIG. 5c shows graphs of soil profiles obtained in experiments with a 445 mm CLF apparatus and medium compaction wherein ▪—is a graph obtained with a cubicle hammer and ●—is a graph obtained with a ball.

FIG. 5d shows graphs of soil profiles obtained in experiments with a 445 mm CLF apparatus and high compaction wherein ▪—is a graph obtained with a cubicle hammer and ●—is a graph obtained with a ball.

As a mine neutralising device the new flail design according to the present invention has the following characteristics:

• • Effectively channels the power from the power shaft and converts it into a series of stress fields, the size, depth and distribution of which can be predetermined to trigger and neutralise landmines buried to a known depth, in a systematic manner limiting the possibility of missing an active landmine of known operating load buried in the area.
  • The rigid links, and knee joints according to the present invention jointly maintain and limit the freedom of movement of the flail to the vertical plane that is established when the flail is rotating freely, before it is lowered and impacts the ground. A cylindrical shape of the hammer mass prevents the hammer from making deep indentation, breaking through the ground surface and ploughing. As this action unnecessarily consumes and waste power and seriously complicates and makes the mine neutralisation process very much unsafe. In reality the lower link permits the cylinder to bounce up after impact and leave the ground surface thus avoiding a ploughing action almost totally.
  • A knee link flail, according to the present invention can be described as a cross between a stress field inducing roller and vertical impacting/pounding shaft, has the capability of reproducing many of the same effects as the two devices, but in a more energy efficient and cost effective manner. Often the flail systems are overall lighter, inexpensive, and less complicated. In the role as an anti mine flail it is easier to manoeuvre over most terrain and the damage resulting from a mine explosion is easy to repair in the field.

The design features that make the knee link flail a good anti mine flail also opens up several commercial applications for the invention. Some possible applications that can be considered may involve crushing, compacting, and foundation building, as in case of roadbed building. Crushing of solids in mining, food, and waste management industry may be the other relevant applications.

TABLE 1
illustrates the average power (w) used by KLF and CLF at
medium and high compaction levels with the power being
measured by a wattmeter
	Total link	Link	Compaction	Hammer	Power
Flail Type	length (mm)	Ratio	Level	type	(W)
KLF	345	1:1	Medium	Ball	1065
				Cube	934
				Roller	1170
			High	Ball	958
				Cube	1046
				Roller	1170
		1:0.5	Medium	Ball	909
				Cube	932
				Roller	1116
			High	Ball	944
				Cube	950
				Roller	1175
	445	1:1	Medium	Ball	1286
				Cube	1211
				Roller	1501
			High	Ball	1385
				Cube	1291
				Roller	1606
		1:0.5	Medium	Ball	1235
				Cube	1279
				Roller	1405
			High	Ball	1309
				Cube	1272
				Roller	1435
CLF	345	—	Medium	Ball	761
				Cube	752
			High	Ball	894
				Cube	875
	445	—	Medium	Ball	1132
				Cube	1169
			High	Ball	1184
				Cube	1189

Variation may be made to the preferred embodiments without departing from the spirit and scope of the invention as defined in the appended claims. For instance, a plurality of single legs with hammers at their outer ends may be rotatably attached to the disc which are connected to the rotatable shaft.

Claims

1. A knee link flail system comprises a rotable shaft mounted horizontally on a carriage with a plurality of flat structures attached to and perpendicular to the rotatable shaft which structures are spaced at predetermined intervals along the rotatable shaft, a plurality of first legs being connected to outer edges of said structures via first rotatable connections, a plurality of second legs each of which are connected to an outer end of an associated first leg via a rotatable connection, a hammer mass being attached to outer ends of each of the second legs to impact against a soil's surface upon rotation of said rotatable shaft.

2. A knee link flail system as defined in claim 1, wherein each flat structure is a disc.

3. A knee link flail system as defined in claim 2, wherein the length ratio of the first and second legs are 1:1.

4. A knee link flail system as defined in claim 2, wherein the length ratio of the first and second legs are 1:0.5.

5. A knee link flail system as defined in claim 3, wherein a total link length of the legs is 345 mm.

6. A knee link flail system as defined in claim 4, wherein a total link length of the legs are 445 mm.