EP4720594A1 - Mobile platform for a weapon - Google Patents

Abstract

A mobile platform (202, 302, 402) for a weapon (206, 306) having a variable angle of elevation of a barrel (208, 308), the mobile platform comprising means for adjusting in real time a height above an underlying terrain at which a recoil force from the weapon acts on the mobile platform so as to maintain stability of the mobile platform during firing of the weapon.

Description

Mobile Platform for a Weapon The present disclosure relates to a mobile platform for a weapon and particularly, but not exclusively, to a mobile platform for a gun system. BACKGROUND The use of mobile platforms to manoeuvre weapons is well established and ranges from historic artillery pieces such as cannons and long-barrelled guns to more contemporary howitzers, mortars and rocket artillery. An example of a traditional mobile weapon system 101 in the form of a towed artillery piece is illustrated in Figure 1. The towed artillery piece typically comprises a gun system 103 having a gun barrel 105 and a gun breech 107. The gun system 103 is mounted on trunnions (substantially cylindrical bearing elements) 109 which enable the angle of elevation of the gun barrel 105 to be adjustable during use. The gun system 103 is supported via the trunnions 109 on a gun mount 113 disposed on a mobile platform 111. The gun mount 113 comprises apertures adapted to cooperate with, and support, the trunnions 109. The mobile platform 111 also comprises a trail assembly 115 that helps counteract recoil forces from the gun system 103 during firing thereof. Examples of such traditional towed artillery pieces include the British L118 and American M119105 mm light field guns in the howitzer class. When the gun system 103 is fired it can have a destabilising effect on the mobile platform 111 upon which it is mounted. This is represented in Figure 1 using the simple case of the gun system 103 firing substantially horizontally. The recoil force (Fr) 121 creates an overturning moment (the product of the recoil force (Fr) 121 and the trunnion height (Ht) 125) that must be matched or exceeded by the restoring moment due to the weight (Mw x g) of the mobile weapon system 101 (the combined weight of the gun system 103 and the mobile platform 111) and the length (Lt) 127 of the trail assembly 115. This is represented by the inequality of expression (1) below: Fr x Ht < Mwg x Lt (1) Traditional weapons and associated carriages have a stable operating envelope that is defined and fixed during design and manufacturing phases in dependence on an operating specification. Stable operation is thereby assured but at the potential expense of operational performance, flexibility and / or efficiency. For example, the operating envelope of a traditional mobile weapon system 101 may be unduly restricted by a stability margin that is not applicable to all firing scenarios / conditions. Alternatively, or in addition, the fixed design of the mobile weapon system 101 may be over specified for other firing scenarios / conditions. For example, the mass of the mobile weapon system 101 may be specified for worst-case scenarios which could lead to inefficiency of use in less demanding scenarios / conditions. There are also consequences for operational deployability due to the heavier mobile platform. It is against his background that the present invention has been conceived. At least in certain embodiments, the present invention seeks to overcome or ameliorate at least some of the problems and shortcomings associated with known mobile weapon systems. SUMMARY OF THE INVENTION Aspects of the invention relate to mobile platform for a weapon, to a controller for a mobile platform having a weapon, to a method of controlling a mobile platform for a weapon, to a computer program and to a mobile weapon system as claimed in the appended claims. According to an aspect of the present invention there is provided a mobile platform for a weapon having a variable angle of barrel elevation, the mobile platform comprising means for adjusting in real time a height above an underlying terrain at which a recoil force from the weapon acts on the mobile platform so as to maintain stability of the mobile platform during firing of the weapon. Varying the height at which the recoil force from the weapon acts on the supporting mobile platform in real time is beneficial in that it facilitates a lightweight solution and enables greater flexibility and performance of operation in theatre. The adjusting means may be configured to adjust the height at which the recoil force acts on the mobile platform such that a restoring moment provided by the mobile platform is equal to or greater than an overturning moment incident on the mobile platform from the recoil force of the weapon during firing of the weapon. This ensures stable operation within a larger operating envelope and over a variety of terrains. In an embodiment, the adjusting means is configured to adjust the height at which the recoil force acts on the mobile platform as a function of the angle of barrel elevation of the weapon. For the avoidance of doubt, the angle of barrel elevation is measured with respect to a horizontal axis of the mobile platform. Optionally, the height at which the recoil force from the weapon acts on the mobile platform is variable by the adjusting means in dependence on the magnitude of a substantially horizontal component of the recoil force from the weapon during firing thereof. For the avoidance of doubt, the horizontal component is measured with respect to the platform (not earth fixed coordinates). In another embodiment, the adjusting means is configured to adjust the height at which the recoil force acts on the mobile platform in real time in dependence on at least two of: recoil force Fr in the direction of the barrel; combined weight of the mobile platform and weapon mg; angle of barrel elevation QE with respect to horizontal; angle of terrain θ underlying the mobile platform with respect to horizontal; anti-clockwise moment arm ACMA_T about a pivot point of the mobile platform to a point at which a recoil force from the weapon acts on the mobile platform; clockwise moment arm CMA_T about a pivot point of the mobile platform to a point at which a recoil force from the weapon acts on the mobile platform; anti-clockwise moment arm ACMA_CoG about a pivot point of the mobile platform to the centre-of-gravity of the combined mobile platform and weapon; and clockwise moment arm CMA_CoG about a pivot point of the mobile platform to the centre-of- gravity of the combined mobile platform and weapon. This embodiment provides an alternative and more comprehensive solution to foregoing embodiments. In a further embodiment, the adjusting means is configured to adjust the height at which the recoil force acts on the mobile platform in real time so as to satisfy the following inequality: ^_^ cos⁽^^ − ^⁾ ∙ ^^^^_^ + ^^ sin⁽^⁾ ∙ ^^^^_^^^ < ^_^ sin⁽^^ − ^⁾ ∙ ^^^_^ + ^^ cos⁽^⁾ ∙ ^^^_^^^ This provides a further refinement to foregoing embodiments. Optionally, the height of the mobile platform above the underlying terrain is variable in dependence on a substantially vertical component of recoil of the weapon during firing. The substantially vertical component of recoil may comprise displacement of the weapon during firing. Accordingly, the height of the mobile platform may be arranged so as to avoid collision between the hull of the mobile platform or a recoiling part of the weapon (by way of non- limiting example, a breach of the weapon) and the underlying terrain during firing of the weapon. This obviates the practice of excavating a pit underneath the mobile platform to receive the hull of the mobile platform or the recoiling part of the weapon during firing. In one embodiment the mobile platform defines an aperture adapted to receive at least part of the weapon during firing thereof. In such an embodiment the aperture in the mobile platform cooperates with a recoiling part of the weapon to allow the recoiling part to pass at least partially there through during firing of the weapon. In one embodiment, the means for adjusting the height at which the recoil force from the weapon acts on the mobile platform comprises a variable height suspension system. The means for adjusting the height at which the recoil force from the weapon acts on the mobile platform may comprise at least one suspension arm articulated at a proximal end thereof to / from a hull of the mobile platform by a moveable joint and terminated at a distal end of the suspension arm by a wheel hub. The joint may be moveable with respect to the hull of the mobile platform in a substantially translational manner or moveable pivotally with respect to the hull of the mobile platform. The wheel hub may be a traction wheel or a wheel member of a continuous track (for example for a skid steered vehicle). The moveable joint may have a first degree of mechanical freedom defining a plane in which the suspension arm is moveable with respect to the hull of the mobile platform. The mobile platform may comprise a plurality of said suspension arms articulated to / from the hull of the mobile platform, each extending outwardly therefrom along at least one of a longitudinal axis and a lateral axis of the mobile platform to form at least one leading suspension arm and at least one trailing suspension arm. At least one of the suspension arms optionally extends outwardly along both longitudinal and lateral axes, i.e. not parallel with either the longitudinal or the lateral axis of the mobile platform. In one embodiment, the adjusting means comprises a controller in operative communication with at least one actuator arranged to alter at least one of a position and an angle at which each suspension arm is articulated to the hull of the mobile platform so as to vary the height of the mobile platform above the underlying terrain. Optionally, each suspension arm is controllable independently to vary the height of the mobile platform above the underlying terrain and further optionally to vary the attitude of the mobile platform. Having at least one leading suspension arm and at least one trailing suspension arm is beneficial in that the suspension arms cooperate during lowering of the mobile platform height to extend at least one of the wheelbase and track width of the mobile platform. This confers additional stability to the mobile platform by extending the effective trail length of the mobile platform as well as adjusting the height at which the recoil force acts on the mobile platform. Each suspension arm optionally comprises a second degree of mechanical freedom within a second plane substantially perpendicular to the first plane. The second degree of mechanical freedom may be provided by the first moveable joint or alternatively by a second moveable joint. Each suspension arm optionally comprises a steerable joint disposed at the end distal thereof from the hull of the mobile platform, said steerable joint adapted to support the wheel hub. One or more of the wheel hubs may be independently powered (a hub drive) to facilitate variation of the wheelbase and / or track width of the mobile platform and / or provide motive propulsion to the mobile platform. The mobile platform may comprise means for varying an azimuth angle of the weapon independent of the orientation of the mobile platform (for example a slew ring). The mobile platform may be configured to extend at least one of the wheelbase and track width of the mobile platform in dependence on the azimuth angle of a barrel of the weapon. According to another aspect of the present invention there is provided a controller for a mobile platform having a weapon, the controller comprising: input means in data communication with the weapon and configured in use to receive data therefrom indicative of an angle of elevation of a barrel of the weapon; processing means configured to: (i) determine an overturning moment incident on the mobile platform from the weapon during firing thereof as a function of at least one of the angle of barrel elevation of the weapon and recoil force from the weapon; (ii) determine in dependence on at least one parameter of the mobile platform a restoring moment provided by the mobile platform in opposition to the overturning moment; (iii) determine a maximum permissible height above an underlying terrain at which a recoil force from the weapon can be permitted to act on the mobile platform such that the determined restoring moment remains equal to or greater than the determined overturning moment; output means arranged to provide an output in real time indicative of the determined maximum permissible height above the underlying terrain at which the recoil force from the weapon can be permitted to act on the mobile platform. The angle of barrel elevation is optionally demanded angle of elevation or actual / prevailing angle of elevation informed by the stage of targeting of the weapon, i.e. pre or post actuation of a weapon control system. In one embodiment, the output means is arranged in operative communication with at least one actuator adapted to vary a height of the mobile platform above the underlying terrain and the output from the output means comprises a demand control signal to the at least one actuator. The demand control signal may comprise a data signal or a power signal capable of direct operation of the at least one actuator. In another embodiment, the input means is configured to receive data indicative of: (iv) combined weight of the mobile platform and weapon mg; (v) fire mission solution; (vi) mobile platform attitude and suspension arm configuration; (vii) angle of barrel elevation QE with respect to horizontal; and the processing means is configured to determine: (viii) angle of terrain θ underlying the mobile platform with respect to horizontal; (ix) recoil force Fr in the direction of the barrel; (x) anti-clockwise moment arm ACMAT about a pivot point of the mobile platform to a point at which a recoil force from the weapon acts on the mobile platform; (xi) clockwise moment arm CMAT about a pivot point of the mobile platform to a point at which a recoil force from the weapon acts on the mobile platform; (xii) anti-clockwise moment arm ACMA_CoG about a pivot point of the mobile platform to the centre-of-gravity of the combined mobile platform and weapon; and (xiii) clockwise moment arm CMA_CoG about a pivot point of the mobile platform to the centre-of-gravity of the combined mobile platform and weapon. (xiv) the maximum permissible height above the underlying terrain at which the recoil force from the weapon can be permitted to act on the mobile platform in dependence on (vii) to (xiii). Without limitation, the fire mission solution may comprise muzzle velocity, projectile mass and optionally barrel elevation. The attitude and suspension arm configuration (angles) may be derived from angle sensors (potentiometers, rotary encoders etc.) and / or ride height calculators etc. In another embodiment, the processor is configured to determine the maximum permissible height above the underlying terrain at which the recoil force from the weapon can be permitted to act on the mobile platform in dependence on the following inequality: ^_^ cos⁽^^ − ^⁾ ∙ ^^^^_^ + ^^ sin⁽^⁾ ∙ ^^^^_^^^ < ^_^ sin⁽^^ − ^⁾ ∙ ^^^_^ + ^^ cos⁽^⁾ ∙ ^^^_^^^ According to another aspect of the present invention there is provided a method of controlling a mobile platform for a weapon comprising: (xv) determining an angle of elevation of a barrel of the weapon; (xvi) determine an overturning moment incident on the mobile platform from the weapon during firing thereof as a function of the angle of barrel elevation of the weapon; (xvii) determine in dependence on at least one parameter of the mobile platform a restoring moment provided by the mobile platform in opposition to the overturning moment; (xviii) determine a maximum permissible height above an underlying terrain at which a recoil force from the weapon can be permitted to act on the mobile platform such that the determined restoring moment remains equal to or greater than the determined overturning moment; (xix) varying the height of the mobile platform in real time to maintain a prevailing height at which the recoil force from the weapon acts on the mobile platform during firing thereof to be lower than or equal to the determined maximum permissible height. The method may comprise receiving data indicative of: (xx) combined weight of the mobile platform and weapon mg; (xxi) fire mission solution; (xxii) mobile platform attitude and suspension arm configuration; (xxiii) angle of barrel elevation QE with respect to horizontal; and determining: (xxiv) angle of terrain θ underlying the mobile platform with respect to horizontal; (xxv) recoil force F_r in the direction of the barrel; (xxvi) anti-clockwise moment arm ACMA_T about a pivot point of the mobile platform to a point at which a recoil force from the weapon acts on the mobile platform; (xxvii) clockwise moment arm CMA_T about a pivot point of the mobile platform to a point at which a recoil force from the weapon acts on the mobile platform; (xxviii) anti-clockwise moment arm ACMA_CoG about a pivot point of the mobile platform to the centre-of-gravity of the combined mobile platform and weapon; (xxix) clockwise moment arm CMA_CoG about a pivot point of the mobile platform to the centre-of-gravity of the combined mobile platform and weapon; and (xxx) the maximum permissible height above the underlying terrain at which the recoil force from the weapon can be permitted to act on the mobile platform in dependence on (xxi) to (xxix). The attitude and suspension arm configuration (angles) may be derived from angle sensors (potentiometers, rotary encoders etc.) and / or ride height calculators etc. In another embodiment, the method comprises determining the maximum permissible height above the underlying terrain at which the recoil force from the weapon can be permitted to act on the mobile platform in dependence on the following inequality: ^_^ cos(^^ − ^) ∙ ^^^^_^ + ^^ sin(^) ∙ ^^^^_^^^ < ^_^ sin(^^ − ^) ∙ ^^^_^ + ^^ cos(^) ∙ ^^^_^^^ According to another aspect of the present invention there is provided a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method as described above. According to another aspect of the present invention there is provided a mobile weapon system comprising a weapon mounted on a mobile platform as described above and / or configured to perform the method as described above. The processor(s), controller(s) and/or functional unit(s) (and various associated elements) described herein may comprise any suitable processing circuitry to cause performance of the methods described herein and as illustrated in the Figures. They may comprise: at least one application specific integrated circuit (ASIC); and/or at least one field programmable gate array (FPGA); and/or single or multi-processor architectures; and/or sequential (Von Neumann)/parallel architectures; and/or at least one programmable logic controllers (PLCs); and/or at least one microprocessor; and/or at least one microcontroller; and/or a central processing unit (CPU), to perform the methods. The processor, controller or functional unit may include at least one microprocessor and may comprise a single core processor, may comprise multiple processor cores (such as a dual core processor or a quad core processor), or may comprise a plurality of processors (at least one of which may comprise multiple processor cores). Two or more of the functional steps of the technology described herein may be carried out sequentially or in parallel on a given processor. Further, functional steps of the technology described herein may be shared amongst and carried out sequentially or in parallel by separate processors. The processor, controller or functional unit may be part of a system that further comprises computer-based input/output means implemented by processing circuitry, or any suitable device for receiving and sending information between the system and a user of the system. The processor, controller or functional unit may be part of a system that includes an electronic display, or any suitable device for conveying information to a user. The processor, controller or functional unit may comprise and/or be in communication with one or more computer memories that store the data for performing the methods described herein, and/or that store software for performing the processes and functions described herein. The processor, controller or functional unit may trigger the fetching of data from the one or more memories and to read the data for the purpose of performing the methods described herein. Outputs from the processor, controller or functional unit may be written back to the memory for further use by the system. The memory may use any present or future memory technology. The memory may be any suitable non-transitory computer readable storage medium, data storage device or devices, and may comprise a hard disk and/or solid-state memory (such as flash memory). The memory may be permanent non-removable memory, or may be removable memory (such as a universal serial bus (USB) flash drive). The memory may store a computer program comprising computer readable instructions that, when read by a processor, controller or functional unit, causes performance of the methods described herein, and as illustrated in the Figures. The computer program may be software or firmware, or may be a combination of software and firmware. The computer readable storage medium may be, for example, a USB flash drive, a compact disc (CD), a digital versatile disc (DVD) or a Blu-ray disc. In some examples, the computer readable instructions may be transferred to the memory via a wireless signal or via a wired signal. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a schematic, side elevation illustration of a traditional, prior art towed artillery piece; Figure 2 is a schematic, side elevation illustration of a mobile platform for a weapon according to an embodiment of the present invention detailing characteristic points of interest; Figure 3 is a schematic, side elevation illustration of a mobile platform for a weapon according to an embodiment of the present invention detailing characteristic dimensions; Figure 4 is a schematic, isometric view of the rear right corner of a mobile platform according to an embodiment of the present invention detailing the characteristic angles that describe the configuration of the rear suspension arm; Figure 5 is a schematic diagram of a control system of a mobile weapon system according to an embodiment of the present invention; Figure 6 is a flow diagram illustrating steps in a method performed by the mobile weapon system in one embodiment of the present invention. DETAILED DESCRIPTION While the basic criterion for stable operation of a simple mobile weapon system is known from expression 1, Applicant is aware that firing stability of a modern mobile weapon system can be a more complex problem. For example, the solution to the problem may also need to take into account changes in muzzle energy, quadrant elevation, changes in platform mass (for example due to consumption of ammunition and / or fuel load in the case of a self-propelled mobile weapon system) and movement of the mobile weapon system centre of gravity during recoil etc. Furthermore, Applicant has arrived at the surprising realisation that introducing an additional degree of freedom (specifically, adjusting the height at which the recoil force from the weapon acts on the supporting mobile platform during operation) facilitates a stable, lightweight platform design and enables greater flexibility and performance of operation in theatre. In the embodiments described herein, a mobile weapon system is defined as a weapon mounted on a mobile platform. Without limitation, the weapon is described in the following embodiments specifically as a gun system; however, the weapon could be any other that experiences a recoil force during operation. For example, optionally the weapon mounted on the mobile platform comprises a mortar artillery system or a rocket propelled artillery system (recognising that firing forces for pure rocket propulsion are much lower than for a gun). In some embodiments, the height at which the recoil force from the weapon acts on the supporting mobile platform is adjustable in real time in a substantially linear manner (upward / downward) by actuators that raise or lower the height of the mobile platform above an underlying terrain. The actuators optionally raise or lower the ride height of the mobile platform for example by altering the length of one or more suspension arms supporting the mobile platform. Alternatively, or in addition, a point at which a suspension arm attaches to the mobile platform may be movable to enable said attachment point to translate with respect to a hull of the mobile platform (thereby adjusting the height of the hull above the underlying terrain). Referring now to Figure 2, a mobile weapon system 200 according to an embodiment of the present invention comprises a mobile platform 202 comprising a platform hull 204 having means for adjusting in real time the height thereof above an underlying terrain. Without limitation, in this embodiment the height adjusting means comprises height adjustable suspension adapted in use to vary the height at which the recoil force F_r from a weapon 206 mounted on the mobile platform 202 acts thereon. In the embodiment illustrated in Figure 2 the weapon 206 comprises a gun system having a gun barrel 208 and a gun breech 210. The gun barrel 208 is mounted in trunnions 212 that enable the angle of elevation of the gun system 206 to be adjustable during use. The gun system 206 is supported via the trunnions 212 on a weapon mount 214 that has apertures adapted to receive, cooperate with and support the trunnions 212. In the present embodiment the height adjustable suspension comprises a plurality of suspension arms 216 (more specifically 216a, 216b, 216c, 216d), each suspension arm 216 articulated at a proximal end from the hull 204 by a movable shoulder joint 218 (218a, 218b, 218c, 218d respectively). The distal end of each suspension arm 216 is terminated by a wheel hub 220 (220a, 220b, 220c, 220d respectively) rotatable about a centre of rotation K1, K2 230. Separation between respective wheel hubs 220a, 220b along a longitudinal axis of the mobile platform 202 defines a wheelbase 222 of the mobile platform 202. Separation between respective wheel hubs 220a, 220c along a lateral axis of the mobile platform 202 defines a track-width 224 of the mobile platform 202. Each movable shoulder joint 218 (218a, 218b, 218c, 218d) enables the respective suspension arm 216 (216a, 216b, 216c, 216d) to move pivotally with respect to the hull 204 about at least one axis of rotation to enable the height of the mobile platform to be varied to improve the stability thereof during use. Each shoulder joint is preferentially arranged inboard of its associated suspension arm to form one or more pairs of leading suspension arms disposed at one (front) end of the mobile platform and one or more trailing suspension arms disposed at the opposite (rear) end of the mobile platform. While not essential, this configuration benefits from a synergy that exists between the height at which the recoil force acts on the mobile platform and the ‘effective’ trail length of the mobile platform provided by the mobile platform suspension. By way of further explanation, lowering the height of the mobile platform reduces the overturning moment incident thereon due to recoil forces from the gun system during firing. In addition, lowering the height of the mobile platform increases the ‘effective’ trail length by increasing the wheelbase of the mobile platform due to the opposing leading and trailing suspension arms. Thus, the reduced overturning moment and increased wheelbase cooperate in a synergistic manner to improve the stability of the mobile platform. Optionally each shoulder joint 218 is arranged to enable the respective suspension arm to move pivotally about at least two (optionally orthogonal) axes of rotation with respect to the mobile platform hull 204. This configuration is optionally used in conjunction with steerable wheel hubs 220 to enable the track-width of the mobile platform to be varied alternative, or in addition, to varying the wheelbase of the mobile platform as a function of the variable height of the mobile platform. Such a configuration is particularly beneficial in embodiments where the weapon mount 214 includes means (for example a slew ring) for varying the azimuth angle (weapon to target bearing) of the weapon independently of the bearing of the mobile platform. This provides a similar synergy to that described above in respect of extending the ‘effective’ trail length by increasing the mobile platform track-width as a consequence of lowering the height of the mobile platform. In all embodiments of the present invention one or more of the wheel hubs 220 (220a, 220b, 220c, 220d) is optionally a self-propelling (e.g. hydraulic or electric) wheel hub comprising a traction motor (and associated gearing as appropriate) housed there-within. The one or more self-propelling wheel hub propels the mobile platform either directly or via a continuous track (in the case of a skid steered mobile platform). In certain embodiments of the invention described hereinafter, each self-propelling wheel hub may be otherwise referred to as an automotive drive. A wheel hub that does not comprise an integral hub traction motor is driven by an automotive drive arranged remotely from the wheel hub, for example disposed on the / each suspension arm or within the hull of the mobile platform. In such cases, tractive power is transferred from a remote automotive drive to a wheel hub via an associated drive train. Legend CoG 226 of the mobile weapon system 200 denotes the Centre of Gravity of the combined mobile platform 202 and the weapon (gun system) 206 mounted thereon. The mobile platform 202 also comprises a controller 228 configured to determine the overturning moment of the mobile weapon system 200 in dependence on a plurality of mission and operational parameters. The controller 228 is arranged in use to adjust the height of the adjustable suspension by altering the pivot angle of the suspension arms 220a, 220b, 220c and 220d to ensure the overturning moment of the mobile weapon system 200 remains less than or equal to the restoring moment provided by the weight and configuration of the mobile weapon system 200. Optionally, the hull 204 of the mobile platform 202 comprises an aperture 229 that cooperates with recoiling part(s) of the gun system 206 (for example but not limited to the gun breech 210) to allow said recoiling part(s) to pass at least partially through the hull 204 during firing of the gun system 206. Further characteristics, attributes, points of interest, dimensions, angles and moment arms of the present embodiment will now be described and discussed with reference to figures 2, 3 and 4, in which: Platform Attributes: mg = Total weight of the mobile weapon system 200 / 300 (i.e. mobile platform 202 / 302 plus gun system 206 / 306). PD = Platform datum plane (defined either by Inertial Measurement Unit (IMU), Tilt sensors, Inertial Navigation System (INS) and elevation encoders or other mechanism). OP = Orthogonal Plane, plane orthogonal to PD, parallel to the mobile platform centre-line. Fr = Recoil force 221 / 321 in the direction of the gun barrel 208 / 308. Points of Interest: CoG = Centre of gravity 226 / 326 of the mobile weapon system 200 / 300. K1 = Position of the centre of rotation 230a / 330a, 230c / 330c for the rear wheels 220a / 320a, 220c / 320c. K₂ = Position of the centre of rotation 230b / 330b, 230d / 330d for the front wheels 220b / 320b, 220d / 320d. S₁ = Connection point 218a / 318a, 218c / 318c at the rear of the mobile platform 302 about which the rear suspension arms 216a / 316a, 216c / 316c articulate. S₂ = Connection point 218b / 318b, 218d / 318d at the front of the mobile platform 302 about which the front suspension arms 216b / 316b, 216d / 316d articulate. T = Point 212 / 312 (trunnion) about which the gun barrel 208 / 308 elevates and through which the Recoil Force Fr 221 / 321 (not illustrated) is applied to the mobile platform 202 / 302. Dimensions: A₁ = Length 332a, 332c of the suspension arm 316a, 316c, or the distance between K₁ 320a, 320c and S₁318a, 318c. A₂ = Length 332b, 332d of the suspension arm 316b, 316d, or the distance between K₂ 330b, 330d and S2318b, 318d. LInt = Inter-shoulder distance 334 (distance between S1 and S2) in the plane parallel to PD. HInt = Inter-shoulder distance 336 (distance between S1 and S2) in the plane perpendicular to PD (is +ve if S2 is above the PD relative to S1). LCoG = Distance 338 between S1 and CoG in the plane parallel to PD. HCoG = Distance 340 between S1 and CoG in the plane perpendicular to PD (is +ve if CoG is above the PD relative to S1). LT = Distance 342 between S1 and T in the plane parallel to PD. HT = Distance 344 between S1 and T in the plane perpendicular to PD (is +ve if T is above the PD relative to S1). r = Radius 346 of the wheel 320 (including tyre; assumes all wheels 320a, 320b, 320c, 320d are the same diameter). Angles (all angles are measured in degrees): QE = Quadrant elevation, or angle of barrel elevation 348 (not illustrated) with respect to horizontal according to earth-fixed coordinates. PE = Mobile platform elevation, angle of the mobile platform 350 (not illustrated) measured by the mobile platform sensors (IMU, Tilt sensors, INS and elevation encoders or other mechanism; incline = +ve, decline = -ve). α1 = Angle 452 of the rear suspension arm below the mobile platform datum plane. α₂ = Angle 454 (not illustrated) of the front suspension arm below the mobile platform datum plane. β₁ = Angle 456 of the rear suspension arm displaced outwards in a plane parallel to the mobile platform centre-line (0° is fully rearward). β₂ = Angle 458 (not illustrated) of the front suspension arm displaced outwards in a plane parallel to the mobile platform centre-line (0° is fully forward). γ₁ = Angle 460 (not illustrated) between the rear suspension arm once projected onto OP, and the vertical according to earth-fixed coordinates: ^_^ γ2 = Angle 462 (not illustrated) between the front suspension arm once projected onto OP, and the vertical according to earth-fixed coordinates: ^ ⁾ In order to calculate the angle of the ground upon which the mobile weapon system 200, 300, 400 is situated with respect to earth-fixed coordinates, the length of the suspension arms projected onto OP must be calculated: X1 = Length of the rear suspension arm projected onto OP: X₂ = Length of the rear suspension arm projected onto OP: ^_^ = ^⁽^_^ ^^^⁽^_^ ^{))^} ₊ ⁽ _{^^ ^^^} ⁽ _^^ ⁾ _^^^ ⁽ _^^ ^{))^} (5) θ = Angle 464 (not illustrated) of the ground upon which the mobile weapons system is situated with respect to horizontal according to earth-fixed coordinates (assuming all wheels are making contact with the ground): ^_^ ^^^ ^ +^_^^^ ^^^ ^^ + ^ ^^^ − ^ ^^^ ^ ^ _{^^^ ^} Moment Arms: CMACoG = Clockwise moment arm from the pivot point of the mobile platform to the CoG of the combined mobile platform and weapon parallel to the ground, where: ^^^_^^^ = ^_^ sin(^_^ + ^) + cos(^ − ^^) ∙ (^_^^^ + ^_^^^ tan(^ − ^^)) (7) ACMACoG = Anti-clockwise moment arm about the pivot point of the mobile platform to the CoG of the combined mobile platform and weapon, where: CMAT = Clockwise moment arm about the pivot point to the T, where: ^^^_^ = ^_^ sin⁽^_^ + ^⁾ + cos⁽^ − ^^⁾ ∙ ⁽^_^ + ^_^ tan⁽^ − ^^⁾⁾ (9) ACMAT = Anti-clockwise moment arm about the pivot point to the T, where: ^ ^^^^_^ = ^ + ^_^ cos⁽^_^ + ^⁾ + _^ − sin cos(^ − ^^) ⁽^ − ^^⁾ ∙ ⁽^_^ + ^_^ tan⁽^ − ^^⁾⁾ (10) In one embodiment, the controller 228, 328, 428 is configured to determine the overturning moment of the mobile weapon system 200, 300, 400 in dependence on quadrant elevation, or angle of barrel elevation, QE 348 (not illustrated in the figures) with respect to horizontal according to earth-fixed coordinates. In some embodiments, the system controller adjusts the height of the mobile platform in real time in a substantially linear manner (upward / downward) by altering the length of one or more suspension arms supporting the mobile platform or translating a point at which a suspension arm attaches to the mobile platform to ensure the overturning moment of the mobile weapon system 200, 300 remains less than or equal to the restoring moment provided by the weight and mobile platform configuration of the mobile weapon system 200, 300. Alternatively, or in addition, the system controller 228, 328, 428 adjusts the height of the mobile platform in real time by altering the pivot angle of the adjustable suspension arms 220, 320 to ensure the overturning moment of the mobile weapon system 200, 300 remains less than or equal to the restoring moment provided by the weight and mobile platform configuration of the mobile weapon system 200, 300. In addition, or alternatively, in another embodiment, the controller 228, 328 is configured to determine the overturning moment of the mobile weapon system 200, 300 in dependence on the magnitude of a substantially horizontal component of the recoil force Fr 221, 321 from the gun system. In some embodiments, the system controller adjusts the height of the mobile platform in real time in a substantially linear manner (upward / downward) by altering the length of one or more suspension arms supporting the mobile platform, or translating a point at which a suspension arm attaches to the mobile platform, in dependence on the magnitude of a substantially horizontal component of the recoil force Fr from the gun system. In other embodiments, the controller adjusts the height of the mobile platform in real time by altering the pivot angle of the suspension arms 220, 320 in dependence on the magnitude of a substantially horizontal component of the recoil force Fr from the gun system to ensure the overturning moment of the mobile weapon system 200, 300 remains less than or equal to the restoring moment provided by the weight and mobile platform configuration of the mobile weapon system 200, 300. In yet another embodiment, the controller 328 is configured to determine the overturning moment of the mobile weapon system 300 in dependence on at least two of the following parameters: recoil force Fr in the direction of the barrel; combined weight of the mobile platform and weapon mg; angle of barrel elevation QE with respect to horizontal according to earth-fixed coordinates; angle of terrain θ underlying the mobile platform with respect to horizontal according to earth fixed coordinates; anti-clockwise moment arm ACMAT about a pivot point of the mobile platform to a point at which a recoil force from the gun system acts on the mobile platform; clockwise moment arm CMAT about a pivot point of the mobile platform to a point at which a recoil force from the gun system acts on the mobile platform; anti-clockwise moment arm ACMA_CoG about a pivot point of the mobile platform to the centre-of-gravity of the combined mobile platform and weapon; and clockwise moment arm CMA_CoG about a pivot point of the mobile platform to the centre-of-gravity of the combined mobile platform and weapon. In some embodiments, the controller adjusts the height of the mobile platform in real time in a substantially linear manner (upward / downward) by altering the length of one or more suspension arms supporting the mobile platform, or translating a point at which a suspension arm attaches to the mobile platform, in dependence on the overturning moment of the mobile weapon system 300 determined as a function of the at least two abovementioned parameters to ensure the overturning moment of the mobile weapon system remains less than or equal to the restoring moment provided by the weight and mobile platform configuration of the mobile weapon system. In other embodiments, the controller adjusts the height of the mobile platform in real time by altering the pivot angle of the suspension arms 220, 320 in dependence on the overturning moment of the mobile weapon system 300 determined as a function of the at least two abovementioned parameters to ensure the overturning moment of the mobile weapon system 200, 300 remains less than or equal to the restoring moment provided by the weight and mobile platform configuration of the mobile weapon system 200, 300. In another embodiment, the controller adjusts the height of the mobile platform in real time in a substantially linear manner (upward / downward) by altering the length of one or more suspension arms supporting the mobile platform, or translating a point at which a suspension arm attaches to the mobile platform, to adjust the height at which the recoil force acts on the mobile platform in real time so as to satisfy the inequality of expression 11 below: ^_^ cos(^^ − ^) ∙ ^^^^_^ + ^^ sin(^) ∙ ^^^^_^^^ < ^_^ sin⁽^^ − ^⁾ ∙ ^^^_^ + ^^ cos⁽^⁾ ∙ ^^^_^^^ (11) In a yet further embodiment, the controller 228, 328 is arranged to adjust the height of the mobile platform by altering the pivot angle of the suspension arms 220, 320 to adjust the height at which the recoil force acts on the mobile platform in real time so as to satisfy the inequality of expression 11 above. Figure 4 is a schematic, isometric view of the rear right corner of a mobile platform according to an embodiment of the present invention detailing the characteristic angles that describe the configuration of the rear suspension arm. The angles are relative to the x-, y- and z-axis, where the y-axis is in the Mobile platform Datum Plane. Referring now to Figure 5, a control system 500 according to one embodiment of the present invention comprises a controller 528 having processing means (for example a processor) and associated storage means (for example memory) configured to store and execute control software to implement a method of operating the mobile weapon system according to at least one embodiment described herein. The controller 528 comprises input means (analogue and / or digital inputs) configured to receive data from other systems on the mobile weapon system and / or to receive signals from sensors on the mobile weapon system. The controller 528 also comprises output means (analogue and / or digital outputs) configured to transmit data to other systems on the mobile weapon system and / or to transmit control signals to actuators on the mobile weapon system. The controller 528 is arranged in operative communication with a weapon fire control system 574 from which the control system receives data relating to the fire solution, for example projectile mass and muzzle velocity. The control system utilises the fire control data to determine 576 the recoil force incident on the mobile platform 202, 302, 402 and inputs the determined recoil force to the controller 528. The control system determines 580 mobile platform mass and the location of the centre of gravity of the weapon system from mass parameters comprising but not limited to on board fuel level, batteries, ammunition stocks, crew (if any). The controller 528 executes control software configured to implement the method of one of the foregoing embodiments to determine a stable configuration of the mobile platform (in particular a stable height and optionally attitude thereof). Having knowledge of the prevailing mobile platform configuration (e.g. barrel elevation QE and wheel arm / suspension configuration etc.) based on actuator status 578 the controller determines and outputs a demand control signal to control 578 actuators to configure the mobile platform into the desired stable configuration. Once the desired stable configuration has been implemented, a fire safety complete status 588 is output indicative that firing may commence. Firing proceeds under the direction of the weapon system fire controller (optionally in conjunction with the mobile weapon control system 500, especially if firing is to be repeated). While functions of the control system 500 have been illustrated in figure 5 in distinct functional blocks, the skilled person will appreciate that such illustration is not limiting and merely schematic. Accordingly, functions are optionally separable / combinable / movable between distinct functional blocks. A method of operating a mobile weapon system comprising a gun system (having a gun with a barrel and breech) and a mobile platform as described in any of the preceding embodiments will now be described with reference to Figure 6. S610 Mobile weapon system receives fire mission details (target location, ammunition type, etc.). S612 On board fire control computer calculates trajectory data – bearing, elevation, charge zone (muzzle velocity), ammunition type (projectile mass). S613 Projectile and charge are loaded into gun. S614 Mobile platform control system calculates recoil force and recoil stroke. S616 Automotive drives orientate the mobile platform so the barrel centre line is on the gun to target bearing. S618 Receive data from IMU on mobile platform and suspension arm encoders. S620 Determine fore / aft and cross slopes of surrounding terrain in dependence on data received from inertial measuring unit on the mobile platform and the suspension arm encoders. S622 Optionally assess clearance beneath the mobile platform using cameras / sensors. S624 Gun elevation system positions the barrel at the correct quadrant elevation. S626 Sensors on the mobile platform determine fuel load, ammunition stock and other mobile platform variables to determine mobile weapon system weight and centre of gravity. S628 Mobile platform control system calculates the overturning moment due to firing. S630 Mobile platform control system determines the position of the suspensions arms that will provide a restoring moment greater than the overturning moment, maintain mobile platform stability on firing and at the same time ensures that the gun system will not strike the ground at maximum recoil. S632 Mobile platform control system drives suspension arms to achieve the correct trunnion height and orientation. S634 Mobile platform control system, gun elevation system and automotive drives make corrections to achieve the correct trunnion height, quadrant elevation and gun to target bearing. S636 Fire gun. S638 Has the final round been fired? S640 Repeat firing? S642 Reload gun. At least steps S618 to S642 are repeated until the repeat firing instruction is withdrawn or until the final round is fired (whichever occurs sooner). Optionally, additional step S616 is repeated in the event the orientation of the mobile platform has been disturbed by the preceding firing. Some of the steps in the preceding method are modified in embodiments of the present mobile platform comprising means (for example a slew ring) for varying the azimuth angle (weapon to target bearing) of the weapon independently of the bearing of the mobile platform. In particular, step S616 is modified to orientate the barrel centre line on the gun to target bearing using the slew ring alternatively, or in addition, to orientating the mobile platform. Operating the slew ring to orientate the gun on the final target bearing is optionally achievable as part of the elevation step S624 and / or as part of a final target bearing adjustment as described at S634. It will be appreciated by the person skilled in the art that features in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, method aspects may be applied to apparatus aspects, and vice-versa. It will further be understood that the various embodiments disclosed herein have been described for the purposes of illustration and that modifications may be made without departing from the scope of the present disclosure. By way of specific example, all the embodiments of the present mobile weapons system have been described and illustrated herein with reference to a mobile platform having a height adjustable suspension comprising four suspension arms and four wheel hubs. However, the skilled person will appreciate that this is non-limiting and the present mobile platform may comprise fewer or more suspension arms and associated wheel hubs, typically 6, 8 or more wheels. In variants having more than four suspension arms / wheel hubs, separation between the outermost respective wheel hubs along a longitudinal axis of the mobile platform (i.e. the front and rear wheel hubs) defines the wheelbase of the mobile platform. Irrespective of the number of suspension arms / wheel hubs, the platform stability problem and solution are substantially the same as described hereinbefore with regard to the four-wheel embodiments; the set or sets of suspension arms / wheel hubs interposed between those outermost (front and rear) acting largely as ‘outriggers’ providing enhanced lateral stability to the mobile platform. Similarly, all the embodiments of the present mobile weapons system have been described and illustrated herein with reference to a weapon comprising a gun system. However, the skilled person will appreciate that this is non-limiting and the present mobile platform is suitable for use with any weapon that experiences a recoil force during operation. For example, optionally the weapon mounted on the mobile platform comprises a direct fire gun system, mortar artillery system or a rocket propelled artillery system. In such alternative weapons, one or more launch tubes replace the barrel of the gun system described and illustrated in the foregoing embodiments. Accordingly, in the interests of clarity, the launch tube(s) of a mortar artillery system or a rocket propelled artillery system shall be defined as the barrel(s) thereof for the purpose of this patent specification. Where appropriate, features implemented in hardware may be instead implemented in programmable hardware (such as FPGA etc.), firmware or software, and vice versa.

Claims

CLAIMS 1. A mobile platform for a weapon having a variable angle of barrel elevation, the mobile platform comprising means for adjusting in real time a height above an underlying terrain at which a recoil force from the weapon acts on the mobile platform so as to maintain stability of the mobile platform during firing of the weapon. 2. A mobile platform according to claim 1 wherein the adjusting means is configured to adjust the height at which the recoil force acts on the mobile platform such that a restoring moment provided by the mobile platform is equal to or greater than an overturning moment incident on the mobile platform from the recoil force of the weapon during firing of the weapon. 3. A mobile platform according to claim 1 or 2 wherein the adjusting means is configured to adjust the height at which the recoil force acts on the mobile platform as a function of the angle of barrel elevation of the weapon. 4. A mobile platform according to any one of claims claim 1 - 3 wherein the height at which the recoil force from the weapon acts on the mobile platform is variable by the adjusting means in dependence on the magnitude of a substantially horizontal component of the recoil force from the weapon during firing thereof. 5. A mobile platform according to any one of claims claim 1 - 4 wherein the adjusting means is configured to adjust the height at which the recoil force acts on the mobile platform in real time in dependence on at least two of: recoil force F_r in the direction of the barrel; combined weight of the mobile platform and weapon mg; angle of barrel elevation QE with respect to horizontal; angle of terrain θ underlying the mobile platform with respect to horizontal; anti-clockwise moment arm ACMA_T about a pivot point of the mobile platform to a point at which a recoil force from the weapon acts on the mobile platform; clockwise moment arm CMA_T about a pivot point of the mobile platform to a point at which a recoil force from the weapon acts on the mobile platform; anti-clockwise moment arm ACMA_CoG about a pivot point of the mobile platform to the centre-of-gravity of the combined mobile platform and weapon; and clockwise moment arm CMA_CoG about a pivot point of the mobile platform to the centre-of-gravity of the combined mobile platform and weapon. 6. A mobile platform according to claim 5 wherein the adjusting means is configured to adjust the height at which the recoil force acts on the mobile platform in real time so as to satisfy the following inequality: ^_^ cos⁽^^ − ^⁾ ∙ ^^^^_^ + ^^ sin⁽^⁾ ∙ ^^^^_^^^ < ^_^ sin⁽^^ − ^⁾ ∙ ^^^_^ + ^^ cos⁽^⁾ ∙ ^^^_^^^ 7. A mobile platform according to any one of the preceding claims wherein the height thereof above the underlying terrain is variable in dependence on a substantially vertical component of recoil of the weapon during firing. 8. A mobile platform according to any one of the preceding claims wherein the means for adjusting the height at which the recoil force from the weapon acts on the mobile platform comprises a variable height suspension system. 9. A mobile platform according to any one of the preceding claims wherein the means for adjusting the height at which the recoil force from the weapon acts on the mobile platform comprises at least one suspension arm articulated at a proximal end thereof to / from a hull of the mobile platform by a moveable joint and terminated at a distal end of the suspension arm by a wheel hub. 10. A mobile platform according to claim 9 comprising a plurality of said suspension arms articulated to / from the hull of the mobile platform, each extending outwardly therefrom along at least one of a longitudinal axis and a lateral axis of the mobile platform to form at least one leading suspension arm and at least one trailing suspension arm. 11. A mobile platform according to claim 10 wherein the adjusting means comprises a processor in operative communication with at least one actuator arranged to alter at least one of a position and an angle at which each suspension arm is articulated to the hull of the mobile platform so as to vary the height of the mobile platform above the underlying terrain. 12. A mobile platform according to any preceding claim comprising means for varying an azimuth angle of the weapon independent of the orientation of the mobile platform and wherein the azimuth adjusting means is configured to extend at least one of the wheelbase and track width of the mobile platform in dependence on the azimuth angle of the barrel of the weapon. 13. A controller for a mobile platform having a weapon, the controller comprising: input means in data communication with the weapon and configured in use to receive data therefrom indicative of an angle of elevation of a barrel of the weapon; processing means configured to: (i) determine an overturning moment incident on the mobile platform from the weapon during firing thereof as a function of at least one of the angle of barrel elevation of the weapon and recoil force from the weapon; (ii) determine in dependence on at least one parameter of the mobile platform a restoring moment provided by the mobile platform in opposition to the overturning moment; (iii) determine a maximum permissible height above an underlying terrain at which a recoil force from the weapon can be permitted to act on the mobile platform such that the determined restoring moment remains equal to or greater than the determined overturning moment; output means arranged to provide an output in real time indicative of the determined maximum permissible height above the underlying terrain at which the recoil force from the weapon can be permitted to act on the mobile platform. 14. A controller according to claim 13 wherein the output means is arranged in operative communication with at least one actuator adapted to vary a height of the mobile platform above the underlying terrain and wherein the output from the output means comprises a demand control signal to the at least one actuator. 15. A controller according to claim 12 or 13 wherein the input means is configured to receive data indicative of: (iv) combined weight of the mobile platform and weapon mg; (v) fire mission solution; (vi) mobile platform attitude and suspension arm configuration; (vii) angle of barrel elevation QE with respect to horizontal; and the processing means is configured to determine: (viii) angle of terrain θ underlying the mobile platform with respect to horizontal; (ix) recoil force Fr in the direction of the barrel; (x) anti-clockwise moment arm ACMAT about a pivot point of the mobile platform to a point at which a recoil force from the weapon acts on the mobile platform; (xi) clockwise moment arm CMAT about a pivot point of the mobile platform to a point at which a recoil force from the weapon acts on the mobile platform; (xii) anti-clockwise moment arm ACMACoG about a pivot point of the mobile platform to the centre-of-gravity of the combined mobile platform and weapon; and (xiii) clockwise moment arm CMACoG about a pivot point of the mobile platform to the centre-of-gravity of the combined mobile platform and weapon. (xiv) the maximum permissible height above the underlying terrain at which the recoil force from the weapon can be permitted to act on the mobile platform in dependence on (vii) to (xiii). 16. A controller according to claim 15 wherein the processor is configured to determine the maximum permissible height above the underlying terrain at which the recoil force from the weapon can be permitted to act on the mobile platform in dependence on the following inequality: ^_^ cos⁽^^ − ^⁾ ∙ ^^^^_^ + ^^ sin⁽^⁾ ∙ ^^^^_^^^ < ^_^ sin⁽^^ − ^⁾ ∙ ^^^_^ + ^^ cos⁽^⁾ ∙ ^^^_^^^ 17. A method of controlling a mobile platform for a weapon, the method comprising: (xv) determining an angle of elevation of a barrel of the weapon; (xvi) determine an overturning moment incident on the mobile platform from the weapon during firing thereof as a function of the angle of barrel elevation of the weapon; (xvii) determine in dependence on at least one parameter of the mobile platform a restoring moment provided by the mobile platform in opposition to the overturning moment; (xviii) determine a maximum permissible height above an underlying terrain at which a recoil force from the weapon can be permitted to act on the mobile platform such that the determined restoring moment remains equal to or greater than the determined overturning moment; (xix) varying the height of the mobile platform in real time to maintain a prevailing height at which the recoil force from the weapon acts on the mobile platform during firing thereof to be lower than or equal to the determined maximum permissible height. 18. A method according to claim 17 comprising receiving data indicative of: (xx) combined weight of the mobile platform and weapon mg; (xxi) fire mission solution; (xxii) mobile platform attitude and suspension arm configuration; (xxiii) angle of barrel elevation QE with respect to horizontal; and determining: (xxiv) angle of terrain θ underlying the mobile platform with respect to horizontal; (xxv) recoil force Fr in the direction of the barrel; (xxvi) anti-clockwise moment arm ACMAT about a pivot point of the mobile platform to a point at which a recoil force from the weapon acts on the mobile platform; (xxvii) clockwise moment arm CMAT about a pivot point of the mobile platform to a point at which a recoil force from the weapon acts on the mobile platform; (xxviii) anti-clockwise moment arm ACMACoG about a pivot point of the mobile platform to the centre-of-gravity of the combined mobile platform and weapon; (xxix) clockwise moment arm CMA_CoG about a pivot point of the mobile platform to the centre-of-gravity of the combined mobile platform and weapon; and (xxx) the maximum permissible height above the underlying terrain at which the recoil force from the weapon can be permitted to act on the mobile platform in dependence on (xxi) to (xxix). 19. A method according to claim 18 comprising determining the maximum permissible height above the underlying terrain at which the recoil force from the weapon can be permitted to act on the mobile platform in dependence on the following inequality: ^_^ cos⁽^^ − ^⁾ ∙ ^^^^_^ + ^^ sin⁽^⁾ ∙ ^^^^_^^^ < ^_^ sin⁽^^ − ^⁾ ∙ ^^^_^ + ^^ cos⁽^⁾ ∙ ^^^_^^^ 20. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of any one of claims 17 – 19. 21. A mobile weapon system comprising a weapon mounted on a mobile platform according to any one of claims 1 – 12 and / or configured to perform the method of any one of claims 17 – 19.