ANTENNA POSITIONING SYSTEM

Abstract

An Antenna Positioning System for missile seeker and system development and test comprises an antenna module, and a plurality of tethers, wherein the antenna module is suspended in a position by the tethers and the position is capable of being changed and the antenna module manoeuvred by pulling at least one tether and simultaneously releasing at least one tether. The system is useful for testing and developing Radio Frequency (RF) missile technology in a controlled, simulated environment rather than by live missile firings.

Claims

1. An antenna positioning system for missile seeker and system development and test which comprises: an antenna module; and a plurality of tethers, wherein the antenna module is: suspended in a position by the plurality of tethers, and wherein the position changeable, and the antenna module is manoeuvred by changing a length of at least one tether or tension in at least one tether of the plurality of tethers.

2. The antenna positioning system of claim 1, wherein the position of the antenna module is changeable and the antenna module is manoeuvred in response to pulling at least one tether and simultaneously releasing at least one other tether.

3. The antenna positioning system of claim 1, wherein the antenna module provides a base for an antenna array assembly and the antenna module is a rigid structure designed to handle acceleration loads imposed on it by the plurality of tethers.

4. The antenna positioning system of claim 1, wherein the antenna module is constructed from one or more of the materials selected from (i) plywood, blockboard or particle board; (ii) metal fabrication; (iii) metal castings; (iv) plastic fabrication; (v) plastic moulding; (vi) composite fabrication; and (vii) composite moulding.

5. The antenna positioning system of claim 3, wherein the antenna array assembly is placed centrally in the antenna module.

6. The antenna positioning system of claim 3, wherein the antenna array assembly is attached to a face of the antenna module which faces a Unit Under Test (UUT).

7. The antenna positioning system of claim 6, wherein the antenna array assembly comprises a plurality of antennae and each antenna of the plurality of antennae is angled to point at the centre of the UUT.

8. The antenna positioning system of claim 7, wherein the antenna array assembly comprises: up to 5 antennae representing up to five targets or jammers, or up to 3 antennae representing up to three targets and or jammers.

9. The antenna positioning system of claim 1, wherein each tether is attached to the antenna module via an articulated joint.

10. The antenna positioning system of claim 9, wherein the articulated joint has limited degrees of freedom.

11. The antenna positioning system of claim 9, wherein the plurality of tethers are attached around a periphery and a length of the antenna module at positions optimised to provide the necessary motion and positional accuracy of the antenna module.

12. The antenna positioning system of claim 9, wherein the antenna module has limited or substantially no roll freedom.

13. The antenna positioning system of claim 1, wherein the antenna module has one or more attachment points for one or more RF cables.

14. The antenna positioning system of claim 1, wherein the antenna module has frontal dimensions and a shape to suit the requirements of the antenna array assembly.

15. The antenna positioning system of claim 14, wherein the antenna module comprises a triangular plate having three corners wherein a tether of the plurality of tethers is attached at each of the three corners.

16. The antenna positioning system of claim 15, wherein the tethers is attached to the antenna module via a single axis rotational joint.

17. The antenna positioning system of claim 14, wherein the antenna module comprises a tube closed at an end of the tube to form a face onto which the antenna array assembly is mounted.

18. The antenna positioning system of claim 147, wherein the tube is hexagonal.

19. The antenna positioning system of claim 17, wherein a first set of three tethers of the plurality of tethers are attached to a periphery of the tube near a front of the face and spaced 120? apart.

20. The antenna positioning system of claim 19, wherein a second set of three tethers, that are different than the three tethers in the first set are attached to the periphery of the tube near an end of the tube opposite the front of the face, and spaced 120? apart but offset 60? in relation to the first set of tethers.

21. The antenna positioning system of claim 19, wherein each tether is attached to the module via a dual axis articulated joint.

22. The antenna positioning system of claim 1, wherein the antenna module has a face which is circular or polygonal.

23. The antenna positioning system of claim 1, wherein the antenna module has three to thirty sides.

24. The antenna positioning system of claim 1, wherein the antenna module is manufactured of aluminium, synthetic material or composite material.

25. The antenna positioning system of claim 1, wherein the antenna module comprises a transmission device which transmits a signal; optionally selected from a radio frequency (RF) signal, an infrared signal and a laser signal.

26. The antenna positioning system of claim 1, wherein the antenna module comprises a space frame or is fabricated or moulded.

27. The antenna positioning system of claim 1, wherein each tether comprises a length of flexible material or components having a first end which is attached to the antenna module and a second end which is attached to a winch or pulley.

28. The antenna positioning system of claim 1, wherein each tether is of a material or components that can be drawn into a winch or through pulleys whilst maintaining a required tension to accelerate and position the antenna module.

29. The antenna positioning system of claim 1, wherein a tether of the plurality of tethers positioned above the antenna module has a greater cross section than a tether of the plurality of tethers positioned below the antenna module.

30. The antenna positioning system of claim 1, wherein the antenna positioning systems comprises a minimum of three tethers, each of which are positioned about 120 degrees apart radially.

31. The antenna positioning system of claim 1, which comprises a minimum of six tethers.

32. The antenna positioning system of claim 1, wherein each tether is in tension to hold the antenna module in position.

33. The antenna positioning system of claim 1, which comprises three to 30 tethers.

34. The antenna positioning system of claim 1, wherein at least one tether is multistranded.

35. The antenna positioning system of claim 1, wherein at least one tether comprises a flat braid.

36. The antenna positioning system of claim 1, wherein at least one tether comprises a belt.

37. The antenna positioning system of claim 36, wherein the belt is a toothed belt.

38. The antenna positioning system of claim 1, wherein a support structure is provided and the winches are arranged around the support structure.

39. The antenna positioning system of claim 38, wherein the support structure comprises a frame.

40. The antenna positioning system of claim 38, wherein a radial position of the winches on the support structure matches a radial arrangement of tether attachment points on the antenna module.

41. The antenna positioning system of claim 38, wherein a longitudinal spacing of the winches for front and rear tethers is sufficient to provide 3 degrees of motion (Surge, Heave and Sway) or 5 degrees of motion (Surge, Heave, Sway, Pitch and Yaw).

42. The antenna positioning system of claim 38, wherein a longitudinal position of each winch is fixed, fixed but adjustable, or dynamically variable.

43. The antenna positioning system of claim 38, wherein a longitudinal position of each winch is fixed with a tether passing through an adjustable or dynamically variable position pulley.

44. The antenna positioning system of claim 43, wherein a dynamically variable position pulley is positioned longitudinally using a linear servo motor mounted on a linear track with an integrated position feedback device.

45. The antenna positioning system of claim 1 further comprising: a multi axis control system for controlling servo driven winches; and linear servo motors to adjust a length of each tether between the antenna module and winches to position the antenna module in the required position and orientation.

46. The antenna positioning system of claim 1, further comprising a control system.

47. The antenna positioning system of claim 46, wherein the control system is a multi-axis servo system providing co-ordinated control of each winch and linear motor to wind in, or to let out tethers to position the antenna module at the required azimuth and elevation position and at the required orientation.

48. The antenna positioning system of claim 46, wherein the control system receives a series of data from a Hardware in the Loop (HWIL) host computer, including but not limited to position, rate and acceleration, defining the required motion profile of the antenna module.

49. The antenna positioning system of claim 45, further comprising a safety system which shuts down the Antenna Positioning System in the event that an error is detected by the control system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0129] The invention will now be further described with reference to the accompanying drawings in which:

[0130] FIG. 1 shows a view of a known typical Flight Motion Simulator (FMS);

[0131] FIG. 2 shows a view of a known Target Motion Simulator (TMS);

[0132] FIG. 3 shows a view of a known Target Generator;

[0133] FIG. 4 shows a known Hardware in the Loop system;

[0134] FIG. 5 shows a view of a known Antenna Positioning System curved in both azimuth and elevation; and

[0135] FIG. 6 shows a view of an embodiment according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0136] It will be appreciated that aspects, embodiments and preferred features of the invention have been described herein in a way that allows the specification to be written in a clear and concise way. However, unless circumstances clearly dictate otherwise, aspects, embodiments and preferred features can be variously combined or separated in accordance with the invention. Thus, preferably, the invention provides a device having features of a combination of two or more, three or more, or four or more of the aspects described herein. In a preferred embodiment, a device in accordance with the invention comprises all aspects of the invention.

[0137] Within the context of this specification, the word about means plus or minus 20%, more preferably plus or minus 10%, even more preferably plus or minus 5%, most preferably plus or minus 2%.

[0138] Within the context of this specification, the word comprises means includes, among other things and should not be construed to mean consists of only.

[0139] Within the context of this specification, the word substantially means preferably at least 90%, more preferably 95%, even more preferably 98%, most preferably 99%.

[0140] Within the context of this specification, the term antenna array assembly means an assembly comprising a plurality of antennae.

[0141] Within the context of this specification, the word tether means for example cable, cord, cordage, rope, or webbing, for example in the form of braided, woven, or twisted fibres in a long length. Preferably, the tether provides a substantially flexible link, attached to the antenna module that can be shortened or lengthened.

[0142] Suitable tethers include: [0143] 1. Single strand wire [0144] 2. Coated single strand wire [0145] 3. Wire rope [0146] 4. Coated wire rope [0147] 5. Synthetic cord [0148] 6. Synthetic rope [0149] 7. Synthetic woven tape [0150] 8. Synthetic belt [0151] 9. Toothed synthetic belt [0152] 10. Chain

[0153] Within the context of this specification, the word winch means a motorised device to shorten or lengthen the length of the tether between a winch and an antenna module. The winch is a servo-controlled motor which adjusts the length of the tether according to demands from the multi axis digital controller. In the case where the tether is a wire, rope, cord, tape or belt, the winch is provided in the form of a capstan where the tether is wound onto a drum. If the tether is a toothed belt or chain the winch is provided in the form of a toothed pulley arrangement. If the tether is in the form of a tape or belt, the winch assembly needs to be mounted on a pivot so that the winch is always acting at 90? to the tape or belt centreline.

[0154] As shown in FIG. 6, the present invention provides an antenna positioning system (1) which comprises an antenna module (2) suspended and manoeuvred by a series of tethers (3) in the form of cables (4) attached to servo driven winches. Advantageously, the number and positioning of the cables (4) allows the antenna module (2) to be moved in up to and including six degrees of freedom.

[0155] The servo driven winches are controlled by a multi axis control system which adjusts the length of each cable (4) to position the antenna module (2) in the required position and orientation.

[0156] The quantity and positioning of the cables (4) depends upon the required motion of the antenna module (2).

[0157] Without wishing to be bound by theory, there are an infinite number of cable (4) configurations, so the following descriptions assume a symmetrical and basic arrangement for simplicity.

Single Plane Motion

[0158] In a first embodiment, to move the antenna module (2) across a XY plane the cable winches are arranged in a substantially vertical plane. The precise number and positioning of the winches depends upon the range of motion required. If this configuration is used for RF seeker testing the antenna array on the antenna module (2) must be mounted on a two axis gimbal (pitch and yaw) so that the antenna is pointed always at the centre of the UUT.

3D Motion3 DOF Pendant

[0159] In a second embodiment, to move the antenna module (2) in azimuth and elevation whilst maintaining a constant distance from the centre of rotation the module (2) has 3 degrees of freedom (3 DOF). These are, Surge, Heave and Sway. To achieve this range of motion, two pitches of winches are provided with each pitch of winches arranged in a frame (5) around the antenna module (2). The number and position of the winches does not have to be uniformly spaced around the frame (5). For instance, it could be desirable to skew the distribution of winches towards the top of the frame (5) to counteract the bias of gravity on performance. If this configuration is used for HWIL RF seeker testing the antenna array on the antenna module (2) must be mounted on a two axis gimbal (pitch and yaw) so that the antenna is pointed always at the centre of the UUT.

3D Motion5 DOF Pendant

[0160] In a third embodiment, to move the antenna module (2) in azimuth and elevation whilst maintaining a constant distance from the centre of rotation and point at the centre of rotation the module has 5 degrees of freedom (5 DOF). These are, Surge, Heave, Sway, Pitch and Yaw. To achieve this range of motion, two pitches of winches are provided with each pitch of winches arranged in a frame (5) around the antenna module (2). The number and position of the winches does not have to be uniformly spaced around the frame (5). For instance, it could be desirable to skew the distribution of winches towards the top of the frame (5) to counteract the bias of gravity on performance.

[0161] The quantity of winches can be varied to provide more stability to the antenna module or to increase positioning and pointing accuracy. Indeed, due to the difference in the geometry of the front and rear pitches, concave versus convex, the number and positioning of winches may differ between the front and rear pitches.

[0162] The antenna module (2) is attached to the plurality of tethers with flexible connections to allow the module (2) to take up the required position. The module's (2) outer structure is rigid and suitably strong to withstand tension from the tethers (3). An antenna array is attached to the front of the antenna module (2).

[0163] A multi-axis controller is provided to co-ordinate the position (length of tethers (3) between the antenna module (2) and the winches), rate and acceleration of each winch in order to move the antenna module (2) along a required motion path at the required velocity. Position feedback from each winch and or each independent feedback device is used by the controller to close the servo position loop.

[0164] Independent cord-actuated encoders or laser distance sensors provide accurate feedback in relation to the position of the antenna module (2). These encoders or sensors are positioned adjacent to the winches to measure the distance to the antenna module (2) from the winch position.

[0165] The multi-axis controller uses inverse kinematics to control the position, rate and acceleration of the antenna module (2) as required by the real time simulation computer.

[0166] The winches are arranged in a pattern and they are attached to a frame support structure (5). The support structure (5) resists tension from the tethers (3) due to the acceleration of the antenna module (2). The support structure (5) also provides a means to maintain the winches. In this regard, the support structure (5) is relocatable along the Z axis. This provides the advantage of allowing the system's azimuth, elevation and far-field distances to be changed within the dimensional constraints of the design.

[0167] Advantageously, if a multi target system is required, a plurality of single antenna systems can be arranged in tandem each operating at their respective radii which would be at or greater than the far-field distance of the UUT.

[0168] In addition, the inertia of the antenna module (2) and tethers (3) is considerably less than the inertia provided by a traditional system of comparable size. This means that for comparable power input the invention provides greater acceleration for the antenna module (2). As known systems are increased in size to provide a greater field of regard, the inertia generally increases proportionally. This is not the case for the invention as the inertia of additional tether (3) lengths is proportionally small.

[0169] Furthermore, known systems require guide tracks for the antenna module (2) to run along and these tracks have rate limitations. The invention overcomes this limitation as the invention does not require guide tracks.

[0170] The infrastructure of known systems is expensive per square degree and the increase in infrastructure cost is relatively proportional the larger the system requirement. In contrast, a system (1) according to the invention can be made larger with relatively small increases in costs as the infrastructure merely requires marginal changes. This means that customers can more easily afford greater fields of regard.

[0171] The Far-Field radius can be made adjustable by software reconfiguration of the antenna module's radius and making the support structure (or FMS) moveable along the Z axis. This allows different types of missile seekers to be developed at the same facility with an optimum far-field radius and FOR.

[0172] Advantageously, winches can be selected to make it easy to change the rate and acceleration for a given power input. This can be achieved by changing gearing, a pulley size or by selecting a different drum size for the winch.

[0173] The system of the invention can be designed to provide a range of configurations to best suit a range of seekers. This flexibility of rate, acceleration, far-field radius and field of regard would make the facility more cost effective in catering for different seekers.

[0174] Advantageously, the concept system negates the need for expensive infrastructure components and would be increasingly competitive as systems become larger.

[0175] The above described embodiments have been given by way of example only, and the skilled reader will naturally appreciate that many variations could be made thereto without departing from the scope of the invention.