Unmanned Ground Combat Vehicle

UNIVERSITY OF THE WITWATERSRAND, JOHANNESBURG SCHOOL OF MECHANICAL, INDUSTRIAL AND AERONAUTICAL ENGINEERING

COVER PAGE

MECN4005: Design Project Title:

Unmanned Ground Combat Vehicle

Name and Student Number: Gruheet Seetal 806915 Supervisor:

Mr. T. Smit

Date:

23rd August 2018

UNIVERSITY OF THE WITWATERSRAND, JOHANNESBURG

SCHOOL OF MECHANICAL, INDUSTRIAL AND AERONAUTICAL ENGINEERING DECLARATION WITH TASK SUBMITTED FOR ASSESSMENT

I, the undersigned, am registered for the course, Design Project (MECN4005), in the year 2018. I herewith submit the following task, “Unmanned Ground Combat Vehicle” in partial fulfilment of the requirements of the above course.

I hereby declare the following:

o

I am aware that plagiarism (the use of someone else’s work without their permission and/or without acknowledging the original source) is wrong;

o

I confirm that the work submitted herewith for assessment in the above course is my own unaided work except where I have explicitly indicated otherwise;

o

This task has not been submitted before, either individually or jointly, for any course requirement, examination or degree at this or any other tertiary educational institution.

o

I have followed the required conventions in referencing the thoughts and ideas of others;

o

I understand that the University of the Witwatersrand may take disciplinary action against me if it can be shown that this task is not my own, unaided work or that I have failed to acknowledge the sources of the ideas or words in my writing in this task.

Signed on this 23rd day of August 2018.

STUDENT NO. 806915

NAME AND SIGNATURE Gruheet Seetal

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Executive Summary This report details the design of an Unmanned Ground Combat Vehicle (UGCV). A literature survey is done on current UGCV’s and their components, capabilities and problems are discussed. Solutions are proposed based on other military systems such as UAVs and heavily armoured combat vehicles. Three concepts are proposed based on the best performing systems and components surveyed. The concepts are then evaluated against the User Requirement Specifications for the UGCV to determine the best performing concept. The final design is then developed in terms of the vehicles structure, movement capabilities and weapon capabilities. The final design is specified in engineering drawings as well as component lists. The design is then evaluated against the URS and PRS’s and recommendations on required future work are made.

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Table of Contents Cover Page .................................................................................................................................. i Declaration .................................................................................................................................ii 1. Introduction ............................................................................................................................ 1 1.1 Task as Given ................................................................................................................... 1 1.2 Motivation ........................................................................................................................ 1 1.3 Literature Survey .............................................................................................................. 2 1.3.1 iRobot’s 510 Packbot [5] .......................................................................................... 2 1.3.2 Foster-Miller’s MAARS [6] ..................................................................................... 3 1.3.3 Remotec’s Cutlass [13] ............................................................................................. 5 1.3.4 BAE Systems’ “Black Knight” [15] ......................................................................... 7 1.3.5 Considerations for UGCV Development .................................................................. 8 1.3.6 Global Control Communication.............................................................................. 10 1.3.7 Defensive Solutions ................................................................................................ 12 1.3.8 Ordnance Alternatives ............................................................................................ 17 1.3.9 Power Supply .......................................................................................................... 18 1.3.10 Airdrop Procedures and Constraints ..................................................................... 18 1.4 Task as Understood ........................................................................................................ 21 2. User Requirement Specification (URS) ............................................................................... 23 2.1.1 Requirements .......................................................................................................... 23 2.1.2 Constraints .............................................................................................................. 23 2.1.3 Criteria .................................................................................................................... 24 2.1.4 Relevant Military Standards ................................................................................... 24 3 Concept Development ........................................................................................................... 29 3.1 Concept Formation ......................................................................................................... 29 3.1.1 Concept 1: Armoured, Track Driven Vehicle ............................................................. 30 3.1.2 Concept 2: Heavy Ordnance Walker ........................................................................... 32 3.1.3 Concept 3: Flying, Swarm Deployment Drone ........................................................... 34 4. Concept Evaluation .............................................................................................................. 36 4.1 Evaluation Against the URS .......................................................................................... 36 4.1.4 Summary of Evaluation Against the URS .............................................................. 41 iv

4.2 Contextual Evaluation .................................................................................................... 42 4.3 Concept Selection ........................................................................................................... 44 5. Design Development ............................................................................................................ 46 5.1 Product Requirements Specification (PRS) ................................................................... 46 5.2 Analytical Development ................................................................................................. 48 6. Design Specification ............................................................................................................ 81 6.1 Components.................................................................................................................... 81 6.2 Materials ......................................................................................................................... 82 6.3 Costs ............................................................................................................................... 83 7. Engineering Drawings ......................................................................................................... 84 8. Assessment of Design .......................................................................................................... 85 9. References ............................................................................................................................ 90

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List of Figures Figure 1: iRobot's 510 Packbot .................................................................................................. 2 Figure 2: Foster-Miller's MAARS ............................................................................................. 3 Figure 3: Remotec's Cutlass ....................................................................................................... 5 Figure 4: BAE Systems' "Black Knight" ................................................................................... 7 Figure 5: A Survey of UAS LOS Technology by Stansbury et al (2008) ............................... 12 Figure 6: Trophy LV on a Light Armoured Vehicle................................................................ 14 Figure 7: Armour Suite of a BMPT-72 .................................................................................... 15 Figure 8: C-17 Deploying Flares ............................................................................................. 16 Figure 9: Sequence of Events During an Air Drop .................................................................. 20 Figure 11: Competitive Cargo Loads in Terms of No. of 463L Pallets ................................... 21 Figure 10: A CH-35 Airlifting a Light Armoured Vehicle ...................................................... 21 Figure 12: Visual Description of Concept 1 ............................................................................ 30 Figure 13: Visual Description of Concept 2 ............................................................................ 32 Figure 14: Visual Description of Concept 3 ............................................................................ 34 Figure 15: Visual Description of the Final Design Layout ...................................................... 48 Figure 16: The FN M249S ....................................................................................................... 49 Figure 17: The Fostech Origin 12 ............................................................................................ 49 Figure 18: Layout of the IRT System Applied to an M-16 Assault Rifle as Descirbed by Brosseau et al ........................................................................................................................... 51 Figure 19: The Patria AMV XP Armoured Personnel Carrier ................................................ 52 Figure 20: Proposed Shape for the UGCV Body Side plates .................................................. 53 Figure 21: Domex Protect 500 Manufacturer Dimensions for Ballistic Threats ..................... 54 Figure 22: Alustar 5059 H131 Manufacturer Plot for Selecting Material Based on Ballistic Threats...................................................................................................................................... 54 Figure 23: Alustar Mine Blast Protection as Evaluated by the Manufacturer ......................... 55 Figure 24: The Free Body Diagram Used in the Recht-Ipson Model for Oblique Impacts..... 57 Figure 25: Free Body Diagram and Moment Equation of the Top Front Vehicle Body Plate 59 Figure 26: Free Body Diagram and Moment Equation of the Bottom Front Vehicle Body Plate .................................................................................................................................................. 60 Figure 27: Free Body Diagram and Moment Equation of the Back Vehicle Body Plate ........ 61 Figure 28: Plot Used for the Mesh Independence Study ......................................................... 63

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Figure 29: Mesh Used to Evaluate the Static Structural Loads Experienced by the Vehicle Body .................................................................................................................................................. 63 Figure 30: Stress Intensity Results Used to Determine Regions of the Vehicle Body Requiring a Finer Mesh ............................................................................................................................ 64 Figure 31: Ansys FEA Results for the Maximum Principle Stresses Experienced by the Vehicle Body ......................................................................................................................................... 65 Figure 32: Ansys Results for the Total Deformation Experienced by the Vehicle Body ........ 66 Figure 33: Dimensions for the Mattracks 200 Series M1-A1 Tracks ...................................... 68 Figure 34: Free Body Diagram in the Direction of Movement of the UGCV when Accelerating .................................................................................................................................................. 69 Figure 35: Performance of the Rotax 1200 4-TEC Engine as Supplied by Sand-X ................ 69 Figure 36: Free Body Diagram of the UGCV Accelerating Up an Incline ............................. 71 Figure 37: Diagram of the Velocity and Acceleration Model Used for the Turn Execution of the UGCV ................................................................................................................................ 72 Figure 38: Free Body Diagram of the UGCV on a Slope ........................................................ 73 Figure 39: Plot of the Round Velocity vs Range of the 5,56x45mm Round for Manufacturer Data vs Data Produced Via Kinematic Equations ................................................................... 77 Figure 40: Round Velocity vs Distance for Various Buckshot Ammunition as Produced by Brassfletcher.com..................................................................................................................... 78 Figure 41: Impact Characteristics of Various Buckshot Ammunition as Evaluated by Brassfletcher.com..................................................................................................................... 78 Figure 42: Wound Profiles for Various 5,56mm Ammunition as Published by M. Fackler ... 79 Figure 43: The Wound Profile Caused by #4 Buckshot as Published by M. Fackler .............. 79 Figure 44: Diagram of the Angles of View for the Proposed Placement of Cameras on the UGCV ...................................................................................................................................... 80

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List of Tables Table 1: List of NATO STANAG Relevant References ......................................................... 24 Table 2: List of MIL-STD Relevant References...................................................................... 27 Table 3: Performance Characteristics of Concept 1 Evaluated Against the URS ................... 36 Table 4: Performance Characteristics of Concept 2 Evaluated Against the URS ................... 37 Table 5: Performance Characteristics of Concept 3 Evaluated Against the URS ................... 39 Table 6: Summary of the Evaluation of All the Concepts Against the URS ........................... 41 Table 7: Components Required for a Modified IRT System Based on the Design by Brosseau et al. [69] .................................................................................................................................. 50 Table 8: Characteristics of the CS7100 TDS [88] ................................................................... 51 Table 9: Initial Thickness Sizing for Materials Based on Manufacturer Supplied Ballistic Data .................................................................................................................................................. 55 Table 10: Material Strengths .................................................................................................... 58 Table 11: Vehicle Plate Dimensions ........................................................................................ 58 Table 12: Bending Stresses Experienced by The Vehicles Body Plates as Determined Via Hand Calculation ............................................................................................................................... 62 Table 13: Mattracks 200 Series M1-A1 Specifications [93] ................................................... 67 Table 14: Calculation of the Maximum Slope Angle the UGCV Can Traverse ..................... 75 Table 15: Vehicle Performance for a Range of Drive Ratios at An Engine RPM of 7500 Part 1 .................................................................................................................................................. 75 Table 16: Vehicle Performance for a Range of Drive Ratios at An Engine RPM of 7500 Part 2 .................................................................................................................................................. 76 Table 17: Component List for the Final UGCV Specification ................................................ 81 Table 18: Materials and Their Required Thicknesses for the Final UGCV Specification ...... 82 Table 19: Plate Dimensions for the Final UGCV Specification .............................................. 82 Table 20: Approximate Procurement Costs for the UGCV ..................................................... 83 Table 21: Evaluation of the Final UGCV Design Against the URS ........................................ 85 Table 22: Evaluation of the Final UGCV Design Against the PRS ........................................ 86

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Nomenclature UGCV

Unmanned Ground Combat Vehicle

FCS

Future Combat Systems

NATO

North Atlantic Treaty Organisation

GPS

Global Positioning System

EOD

Explosive Ordinance Disposal

RHA

Rolled Homogenous Armour

UAS

Unmanned Aerial Systems

LOS

Line of Sight

BLOS

Beyond Line of Sight

VHF

Very High Frequency

UHF

Ultra High Frequency

APS

Active Protection System

ERA

Explosive Reactive Armour

NERA

Non-Explosive Reactive Armour

HMMWV

High Mobility Multipurpose Wheeled Vehicle

STANAG

Standardization Agreement

MIL-STD

U.S. defense standard

SHF

Super High Frequency

EHF

Extremely High Frequency

USAF

United States. Air Force

ATV

All-Terrain Vehicle

IRT

Inertial Reticle Technology

FPV

First Person View

IED

Improvised Explosive Device

APC

Armoured Personnel Carrier

vr [m/s]

Residual velocity

𝛽 [°]

Rotation of the projectile as it penetrates a plate

𝜌𝑝𝑙𝑎𝑡𝑒 [kg/m2]

Areal density of a plate

𝜌𝑝𝑙𝑢𝑔 [kg/m2]

Sectional density of an impacting projectile

D [m]

Material plug diameter

d [m]

Projectile diameter ix

T [m]

Plate thickness

L [m]

Projectile length

𝜃 [°]

Impact obliquity angle

vi [m/s]

Impact velocity

vbl [m/s]

Material ballistic impact velocity

Sy [MPa]

Material yield strength

Sut [MPa]

Material tensile strength

FEA

Finite Element Analysis

MA,B,C [N.m]

Reaction moment for the three vehicle body plates

RYA,B,C [N]

Vertical reaction force for three vehicle body plates

M [N.m]

Internal bending moment

L [m]

Plate length

x [m]

Arbitrary section distance along plate

𝜎𝑏 [MPa]

Bending stress

y [m]

Distance to outer edge of plate from cross-sectional midpoint

b [m]

Width of plate

h [m]

Height of plate in areal moment of inertia (plate thickness)

Ft,max [N]

Maximum possible tractive force

A [m2]

Track contact area

c [Pa]

Soil cohesion

W [N]

Vehicle weight

𝜙 [°]

Angle of soil internal friction

maG [m/s2]

Acceleration of the UGCV centre of mass

RPM

Revolutions per minute

vbelt [m/s]

Track belt velocity

𝜔𝑎𝑥𝑙𝑒 [rad/s]

Track drive axle rotational speed

dsprocket [m]

Track sprocket diameter

Taxle [N.m]

Track drive axle torque

𝛼 [°]

Arbitrary incline angle

m [kg]

Vehicle mass

g [m/s2]

Acceleration due to gravity assumed 9,81m/s2

d [m]

Distance between track normal and vehicle centre of gravity

x

N [N]

Track normal reaction force

cgh [m]

Height of the UGCV centre of gravity from the ground

t [sec]

time taken in kinematic equations

a [m/s2]

Acceleration in kinematic equations

s [m]

Distance travelled in kinematic equations

vf [m/s]

Final velocity in kinematic equations

Vw [m]

UGCV width

tw [m]

Track width

N1,N2 [N]

Track reaction normal in the UGCV frontal plane

𝛽 [°]

Arbitrary slope angle

L [m]

Distance of track reaction normal from UGCV geometric midpoint

CGG [m]

Distance of UGCV centre of gravity from UGCV geometric midpoint

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1. Introduction 1.1 Task as Given The task as given is to design an unmanned ground combat vehicle for anti-terrorism combat. The vehicle must be able to withstand blasts from grenades and rocket propelled grenades and be able to incapacitate light armoured vehicles such as repurposed 4x4’s as well as enemy personnel. The vehicle must be able to be deployed via airdrop.

1.2 Motivation Unmanned Ground Combat Vehicles (UGCV’s) have been introduced into military operations as supportive elements for the combat function of soldiers. Unmanned ground vehicles are defined by D. W. Gage (1995) in a “dictionary sense” as any piece of mechanized equipment which travels along the ground with the purpose of transporting a payload but does not explicitly carry a person [1]. These robots and vehicles arose from programs such as USA’s Future Combat Systems (FCS) initiative to produce fast and flexible battlefield operations [2]. Many manufacturers produced solutions for the unmanned ground combat class of vehicle with manufacturers designing vehicles with the purpose of fulfilling ordnance disposal, direct combat or utility roles. The U.S. Department of Defence [3] lists the following potential payoffs of using unmanned ground vehicles: •

Reduced risk to human life and increased operational flexibility

•

Savings in operations requiring repetitive work where using manpower exceeds the investment into the task

•

Improved performance in situations where a mechanical system can outperform or eliminate situational compromises because of its lack of physiological fragility such as fear, fatigue or creature comfort

•

Enhancement of force of troops through broader capabilities with UGCV’s as compared to troops without UGCV’s

The advantage that an unmanned vehicle presents on the battlefield is that it does not require the same conditions as a soldier to survive or operate. This means that the class of robots developed for ordnance disposal could do so without fear of damage or environmental

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conditions. Systems such as Foster-Miller’s TALON were designed with a modular approach [4] and the robot could then be adapted for a variety of situations. These situations ranged from chemical, biological, radiological, nuclear and explosive ordnance disposal to rescue, heavy lift, communications, security, reconnaissance and detection of explosive devices. The robot could also be fitted with tactical gear for use in SWAT or police operations. [4]. Due to the variety of situations unmanned ground combat vehicles (UGCV’s) can perform in, manufacturers such as iRobot and Foster-Miller produced vehicles with modular designs with respect to their manipulators. Some examples of UGCV’s and their designs are discussed hereafter. All vehicles can operate in all climates, dust and rain in temperatures ranging from 20° to +60°.

1.3 Literature Survey 1.3.1 iRobot’s 510 Packbot [5]

Figure 1: iRobot's 510 Packbot, image taken from: https://www.armytechnology.com/projects/irobot-510-packbot-multi-mission-robot/

The Packbot is a multi-mission tactical robot designed and manufactured by iRobot to be used by soldiers and first responders on the battlefield which was succeeded by iRobot’s Warrior. The Packbot features rubber tracks and a chassis which are 0,69m long, 0,52m wide and 0,18m tall with a mass of roughly 11 kg. Packbot has been transported by troops in backpacks due to its size and weight. The manipulator of the robot is an arm which is equipped with cable cutters and a hook. Packbot can reach a maximum speed of roughly 9 km/h, can climb inclines of approximately 60° and can operate in water at depths of up to 1m. 2

Sensing for the robot is achieved through a wide array of equipment installed at various locations on the robot. This allows the robot to navigate, identify and analyse its path, environment and any objects of interest to the operator. At the front of the robot’s chassis is an Enhanced Awareness Payload and a wide-angle camera. The end of the arm is fitted with a 312x adjustable zoom camera and infrared lights as well as a Small Arm Manipulator with a colour camera for dexterous work. The Packbot also features a thermal imaging camera, an explosives detection sensor and a HazMat kit for chemical or biological material detection.

Control and communication of the robot is achieved via a digital radio kit which operates at 2.4GHz or 4.9GHz, a two-way audio module, a headphone, a microphone, a GPS and highresolution cameras. Operators command the robot through two game-style controllers which interface with a laptop which can command the robot up to a range of 800m. Operating time of the Packbot is more than 4 hours with power being supplied by two rechargeable lithiumion batteries. The robot also has two spare batteries on board with a battery charger.

1.3.2 Foster-Miller’s MAARS [6]

Figure 2: Foster-Miller's MAARS, image taken from: https://www.qinetiqna.com/wp-content/uploads/DSCN1242gray-muzzle.jpg

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MAARS is the successor of Foster-Miller’s TALON design. TALON was manufactured with a modular design like iRobot’s 510 Packbot. TALON featured an arm manipulator like Packbot but was built slightly larger, having chassis dimensions of 0,86m long, 0,57m wide and 0,28m tall with a maximum mass of 150kg based on its configuration. The vehicle is driven on rubber tracks TALON was widely used for explosive ordnance disposal (EOD) and surveillance by the U.S. military [4] but has the same potential for situational variety as Packbot due to its modularity. TALON was also used extensive in the search and rescue efforts the site of the World Trade Centre after the 9/11 incident where the system proved its durability and reliability [7]. Due to its proven efficacy Foster-Miller’s owning company QinetiQ received a contract to develop another unmanned ground system but with a greater ability to participate in ground combat. This resulted in the combat variant of TALON, the Special Weapons Observation remote Reconnaissance Direct action System TALON. Three SWORD’s were deployed in Iraq and used as patrol robots where they in turn displayed the potential for TALON to participate in direct combat. Thus, the Modular Advanced Armed Robotic System (MAARS) was conceptually born based on control and communication corrections made to SWORDS TALON [8]

MAARS features overall vehicle dimensions of 0,9m long, 0,64m wide and 0,9m in height with a mass of 167 kg. The vehicle can achieve a maximum speed of 11 km/h and climb terrain with maximum inclinations of 42° and traverse slopes of 37°. The vehicle is fitted with rubber tracks which can be swapped to wheels. The extra height of MAARS is due to the mounted turret and fitted sensing equipment as it does not feature a modular design like SWORDS and TALON and was designed and built exclusively to feature in combat. The mounted M20B machine gun fires NATO standard 7,62mm rifle rounds. The M240B has an effective range of 1800m for multiple targets and an effective range of 800m for point targets [9]. MAARS also has four M203 grenade launcher tubes which fire low velocity 40mm grenades which can be varied between lethal, non-lethal and utility rounds such as smoke, illumination and practice rounds. The turret is installed on the TRAP T-360 turret [10] which can rotate 360° with maximum inclination angles of the M240B of -20° and +60°. A laser rangefinder is also installed on the gunnery array to feed ballistic information to the control unit.

MAARS features an array of sensing and communicating equipment. Driving cameras are located at the front and rear of the vehicle, featuring day/night and infrared vision with a field of view of 95°. The gunnery assembly features a daytime and thermal camera which can pan 4

360° and tilt and are part of the vision device, HARV. The daytime camera has up to 312x zoom capability with a 75° field of view and the thermal camera has a 2x zoom capability with a 36° field of view. MAARS also features utility equipment such as a laser warning device, siren and two-way hailer. The vehicle is battery powered and can last between 8 and 12 hours but features a sleep mode to preserve battery life for up to one week. MAARS is radio controlled up to a maximum range of 1km by the wearable Tactical Robotic Controller or through a Toughbook Laptop Controller. The control issues experienced by SWORDS TALON were that it would take too long to respond to commands or the turret would rotate slightly without command [11]. To ensure more secure operation of MAARS, Foster-Miller implemented new software controls which works with a GPS connected to the same network as deployed troops. Zones can be designated as ‘fire’ and ‘no-fire’ zones to the robot and due to the GPS incorporation MAARS is prevented from firing on allies or allied occupied territories [12].

1.3.3 Remotec’s Cutlass [13]

Figure 3: Remotec's Cutlass, image taken from: https://www.researchgate.net/publication/229028828_Investigating_the_mobility_ of_unmanned_ground_vehicles/figures?lo=1

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Cutlass is designed and manufactures by Nothrop Grumman’s subsidiary Remotec. Cutlass is a design focused on use for explosive ordnance disposal but can be outfitted for nuclear and chemical disposal as well. While pursuing the same design goal as TALON, Cutlass is built exclusively for explosive disposal missions (EOD) and does not have the same modular features as TALON. Cutlass has been used by the UK army in the field to dispose of bomb threats in Ireland and Iraq [14]. Cutlass is regarded as the most sophisticated EOD system available as the design incorporates a 9 degree of freedom manipulating arm combined with manoeuvrability and speed greater than its competitors [14].

Cutlass is much larger than TALON having dimensions of 1,3 in length, 0,7m width and 1,2m in height with a typical mass of 420kg. Unlike most other EOD products Cutlass is driven on wheels and not tracks, a trait of Remotec’s design. The wheel drive consists of 6 airless, braked wheels with 200 Nm hub motors. Cutlass can manage a maximum speed of 11 km/h with instant acceleration from 0-11 km/h. The vehicle can manoeuvre over obstacles 0,3m high, across gaps 0,5m long and can climb up to a 38° incline. The vehicle also features an automatic stability system with sensors on its wheels for pitch, roll and load. There is also a feed of vehicle data to the operator and for the vehicle to self-diagnose its operation capability. Cutlass’ manipulating arm lift 25kg and has three links but can be switched to support a 100kg lift for weapon deployment. The arm can also switch between 4 tools and revert to operator defined pre-set positions and provides roughly a 3m reach for the vehicle. Cutlass has an auxiliary lowprofile three fingered gripper which can support up to 20 kg and has an integral ceramic wire cutter.

Cutlass features seven daytime colour cameras with lighting. Two cameras are positioned at the front of the vehicle for forward driving. One camera is positioned at the rear of the vehicle. Another camera is placed on the manipulator arm and a camera is also placed on the optional weapon lift. The final two cameras are placed on the gripper. All the cameras feature no magnification and the vehicle has the option to support a pan and tilt camera similar to the HARV assembly on MAARS. The vehicle also has a microphone for added situational awareness. Cutlass has a 3 hours operating time with power supply from an on board 42V Lithium Ion battery. The battery is rechargeable with a recharge time of 2 hours. The vehicle is radio controlled with a line of site range of up to 1 km and can also be controlled by fibre optic cable with lengths of 200m or 500m.

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1.3.4 BAE Systems’ “Black Knight” [15]

Figure 4: BAE Systems' "Black Knight", image taken from: http://www.militarytoday.com/apc/black_knight.htm

Black Knight was developed by British BAE systems is still currently under testing and development in the United States. Black Knight is designed to be used as an intelligence reconnaissance and planning tool for direct engagement armoured combat vehicles and troops in the field. Black Knight observes targets and terrain at a close range without worry of danger as there would comparatively be for troops in the same operation [16]. Black Knight’s armour and vehicle design is based on the Bradley fighting class of combat vehicle employed by the United States. This means that replacement parts for the vehicle are readily available Black Knight is much larger than other UGCV’s having dimensions of 5m in length, 2,4m of width and a height of 2m. The vehicle weighs 9 tonnes and requires airlifting by a Lockheed C-130 Hercules which has a maximum payload of 20 tonnes [17]. Black Knight is driven on tracks and powered by a 300bhp Caterpillar diesel engine which provides a top speed of 72 km/h. The vehicle is able to manoeuvre on all terrain types and can match the speed of main battle tanks. Black Knight’s main turret is a 30 mm cannon and supported by a coaxial 7,62 mm machine gun. The 30 mm rounds fired by the main cannon are widely used for anti-material and antivehicle applications [18]. The round was developed for air to ground anti vehicle attacks and is used in aircraft such as the Apache Helicopter and A-10 Thunderbolt but has been applied 7

to land-based ordnance systems due to its excellent performance. At 500 m a 30 mm x 113 has an armour penetration of 25,4 mm RHA. [18]. Like the other UGCV’s discussed, Black Knight features a support fire 7,62 mm machine gun for reliable and effective anti-personnel performance. Black Knight’s sensing equipment is based on improving the system used in Bradley fighting class vehicles. The Improved Bradley Acquisition System (IBAS) consists of a forward facing infrared camera, a day camera, a dual target tracker, a laser range finder and a stabilised head mirror assembly [19]. The information from IBAS is fed to the Commander’s Independent Viewer and the commander’s station in a near Bradley vehicle where Black Knight is controlled from [20]. Alternatively, Black Knight can be controlled from troops on foot from a Dismounted Control Device (DCD). Black Knight features a level of autonomy which allows the vehicle to analyse and plan routes through terrain and avoid obstacles. Black Knight is still undergoing evaluation and testing with problem areas in the system’s design being mainly around wireless communication.

1.3.5 Considerations for UGCV Development Drawing on the solutions offered by the UGCV’s discussed, the general design of a groundbased combat vehicle has not changed greatly with the introduction of different models in their sensing, basic design and ordnance [21]. The problems with combat ground vehicles centre around their sensing, operator-to-vehicle interface and wireless communication. [22]. The problems surrounding sensing are to do with the dimensions required by sensing equipment and by the data these pieces of equipment provide. The feed from cameras must provide definition with a quality that operators can use to make informed decisions during operation. This creates a problem in that to produce such definition the cameras must be capable of large magnification and consequentially have a small field of view. Therefore, the operator must deal with camera feed which moves a lot as the vehicle drives over rough terrain and limits the operator’s awareness of the vehicles local environment as a result of the limited peripheral vision. Another problem is a lack of depth provided by the camera feed. This coupled with a lack of local-space visualisation or awareness has resulted in disorientating the vehicle operator [23].

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Another aspect of the vehicle-to-operator interface which poses a problem is that of wireless communication with the vehicle. All the discussed UGCV’s made use of short range, radio control protocols. The maximum range achieved was by Cutlass and MAARS with a value of 1km. SWORDS however was shown to have minor control problems when it was first deployed to Iraq. According to an interview by Popular Mechanics with an Army Program Manager, Kevin Fahey [24] SWORDS’ turret moved slightly without command and had incidents of control signals being so weak that movement of the vehicle only initiated after eight seconds or so after the command was issued [8]. MAARS as a successor to SWORDS has built in functions which deny movement of the robot if a command signal is not received immediately. MAARS also features three part firing safety mechanisms with a kill switch to shut down the entire vehicle [8]. As part of the concerns of communication with UGCV’s, their interoperability with other systems such as GPS and data feed with other reconnaissance vehicles need to reliable and must occur immediately. The vehicle must be capable of rapidly identifying and tracking civilian, friendly and hostile targets through feed to the operator from its own equipment and from the data of other surveillance systems This is to ensure the vehicle does not target civilian or friendly personnel. Efficient communication of the UGCV with other systems in use during a combat situation will allow for well-coordinated movements and produce smoother operations in any combat environment.

The intended environment for the operation of a UGCV plays a role in determining what kind of movement capabilities it must possess. The deployment of SWORDS, Packbot and MAARS to Iraq means that these UGCV’s will be operating in urban environments. Over the past ten years terrorist activities have increased in urban areas such as major cities, with terrorists targeting embassies and large gatherings of the public [25]. Thus, it is evident that UGCV’s of the future must be capable of navigating urban environments as well as being able to perform reliably in rugged terrains. A characteristic of urban environments is the reduced range of combat as compared to engaging an enemy in a rural environment. The maximum range likely to be found in an urban environment is firing down a road, across a highway or from building to building. It is however more common that a UGCV in an urban environment will encounter hostiles at a short range such as in a room, hallway or within a yard. At this range the UGCV’s discussed apart from Black Knight are extremely vulnerable if they can be flanked or

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approached to within touching distance by an enemy. Therefore, defensive and armour considerations become extremely important for point blank encounters.

As part of the environmental considerations to the design of a UGCV, the main body of the vehicle is designed and manufactured to be waterproof. This allows the vehicle to function in all terrain types without the risk of any electrical components malfunctioning or small mechanical components failing due to dirt. Sealing off the main body does however cause a problem for the vehicle in terms of its thermal management. Heat generated by the vehicle’s motors and electrical components is harder to dissipate and the vehicle is prone to overheating. In the case of SWORDS’ deployment to Iraq there were three incidents which the robot did not function correctly. Two of the incidents involved circuitry which mechanically failed leading the design team of MAARS to double solder very joint and have redundant wiring throughout the vehicle. The final incident involved a test where the robot was left to run on incline for two and a half hours where the vehicle overheated [11]. The electrical problems were addressed but the case of overheating illustrates that the vehicles overall system must be analysed in as many different respects as possible. To provide a solution to the problems discussed regarding the UGCV systems new technology must be introduced. This technology can either be invented or may more easily be reinterpreted from existing solutions and applied to the design of a UGCV. Some technology or systems used in other combat systems which may be applicable to UGCV design are discussed hereafter in the following categories: global control communication, defensive solutions, ordnance alternatives, power supply and air drop procedures and constraints.

1.3.6 Global Control Communication All the UGCV systems discussed featured line-of-sight (LOS) wireless radio control capability or could be cable controlled up to 500 m. As discussed earlier, current UGCV systems experience problems with wireless control. It is therefore important that newer UGCV designs offer control communication which is reliable and instantaneous. Unmanned aerial vehicles (UAV’s) have been used far more than their ground-based counterparts, with the United States operating an estimated 670 drones alone in 2016 [26]. Since UAV’s operate at higher altitudes with operating ranges from 50 km to 200 km [27] and therefore can not always be LOS controlled. Beyond line-of-sight (BLOS) control has primarily been by very high frequency (VHF), ultra-high frequency (UHF) or satellite control. VHF frequencies range from 30-300 10

MHz and UHF frequencies range from 300-1000 MHz [28]. Satellite control has been through radio command transmitted via satellite from ground control stations at Ku-band radio frequencies such as for the Predator and Global Hawk UAV’s [29]. Ku-band frequencies range from 12-18 GHz [28]. The problem with radio control is that many different control stations and vehicles are using the same frequencies which make the channels vulnerable to interference [29]. Radio frequencies are also affected by weather conditions, although low GHz frequencies have shown to be less affected by extreme weather conditions [29]. In order to command a UAV via SATCOM, specialised equipment was required for each make of UAV. According to the senior director of aerospace and defence at Wind River Systems, newly designed systems will have to have systems architectures which can integrate with a vast range of hardware and software [30]. Due to this requirement communications technology in the military must make use of commercial technologies such as LTE wireless internet mediums. LTE offers high data transfer speeds at low latency with a global coverage. SATCOM has made advancements in this respect with Inmarsat’s SwiftBroadband satellites. These satellites allow global UAV control via broadband and only require a few minutes to connect to a satellite. These satellites were launched in 2013 and operate in the L-band and Ka-band frequencies which are in the 950-1450 MHz and 26,5-40 GHz frequency ranges respectively. These frequency bands offer resilience and high data rates and can provide real time data feed of on board sensors. In to ensure the security of these signals on commercial internet streams 256 AES (advanced encryption standard) encryption is used. The link to a UAV can be achieved via an Ethernet connection or via satellite if there is no Ethernet capability available. Using a satellite link produces latencies of less than 2 seconds [31]. As a precautionary measure with global wireless control, UAV’s must also have local LOS radio control capability. Some LOS radio communication technologies used by some UAV’s are shown in figure 5 taken from A Survey of UAS Technologies for Command, Control and Communication by Stansbury et al. (2008) [29].

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Figure 5: A Survey of UAS LOS Technology by Stansbury et al (2008) [29]

The greatest LOS range of the listed UAV’s is achieved by Mantta B’s ISM Band Radio Modem which offers LOS control range of up to 24-32 km.

1.3.7 Defensive Solutions UGCV’s such as MAARS and SWORDS were intended to be integrated into direct combat missions. These UGCV’s were meant to be transportable and deployable by vehicle and so their dimensions and mass were limited in that respect. What this meant is that armour possibilities were not included and therefore left mechanical operating mechanisms such as the turret controller and delicate sensing equipment such as cameras exposed. Black Knight on the other hand was developed from an already existing military vehicle and has ballistic armour as 12

a base. As part of the considerations for new UGCV’s the vehicles need to be able to protect themselves from enemy fire and reduce the impact of close range encounters with the enemy which would leave them vulnerable. Defence of the vehicle can be separated into hard-kill and soft-kill measures. Hard-kill measures physically intervene with projectiles before or when they impact the vehicle. Soft-kill measures employ diversionary measures to mask or confuse the physical signature of the vehicle [32]. Some hard-kill and soft-kill countermeasures are discussed hereafter.

Hard-kill Systems Hard-kill measures usually involve systems which destroy, disturb or prematurely initiate an incoming explosive or round. On the market active protection systems (APS) make use of an on board short range radar to quickly identify and plan the trajectories of approaching threat ammunition. An on-board computer then decides whether to engage the projectile, the point of engagement and what ammunition type to use. Ammunition types commonly used are metal pellets similar to shotgun rounds and small missiles [33]. The on-board radar systems also identify the direction of the target lock or trajectory of the incoming projectile to face the vehicles heavy armour towards the target or can be used to locate the enemy. There are several field proven hard-kill APS systems already in use by the U.S., Israel, Russia and the U.K. These systems all operate on the basic procedure described above. The names of these systems and their developers are: Israel’s Trophy System, Israel Military Industries’ Iron Fist, Raytheon’s Quick Kill System, ARTIS’ Iron Curtain System and Rheinmetall Defence’s Active Defence System [33]. All these systems are designed to operate on tanks or other large combat vehicle. Rafael Advanced Defence Systems’ Trophy LV system has been developed based on the original Trophy design. It offers a smaller version of the same system weighing up to 200 kg, only half of the original Trophy’s mass was designed for use on light vehicles (less than 8 tons) such as 4x4’s [34]. One unit of the Trophy LV system is illustrated in figure 6. Another subset of hard-kill systems are passive protection systems. Passive protection systems refer to armour as the system does not have to be switched on to operate.

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Figure 6: Trophy LV on a Light Armoured Vehicle, image taken from: https://www.armyrecognition.com/mspo_2016_news_official_online_show_daily_coverage/the_r afael_advanced_systems_trophy-lv_active_protection_system_at_mspo_2016.html

Armour plays the role of a physical barrier between a projectile and any occupants or vital mechanical parts of the vehicle. Armour systems can be made of steel, aluminium, titanium or composites [35]. The function of armour is to deflect, destroy or damage an impacting projectile so that its penetrative or destructive effects lessened. Two of the most important material properties of the materials used for armour are the materials’ hardness and impact toughness. Materials such as steel, aluminium and titanium offer higher material strengths and impact toughness but are not as hard as composites or ceramics. Composites however offer higher hardness, lower densities and higher elastic moduli [35]. Composite materials also do not rust which can extend the service life of an armour piece.

Armour systems have been utilized in various configurations to defeat different types of projectiles based on the armour material used. Metal armours offer increased protection when sloped, rounded or spaced. Spaced armour reduces the effectiveness of kinetic energy penetrators such as armour piercing rounds by causing the projectile to deflect or deform in between plates [36]. Spaced armour can also reduce the effectiveness of chemical penetrators such as high-explosive anti-tank (HEAT) and high-explosive squash head (HESH) rounds by causing premature detonation of the round in the space between armour plates and not into 14

crew occupied spaces [36]. Examples of extremely spaced armour is the use of slat or mesh armour which are used to protect the vehicle against shaped charges like the explosive of rocket propelled grenades (RPG’s), by deforming the explosive or damaging it sufficiently to prevent the projectile from exploding [37]. These armour types create extremely light protective structures as compared to sloped and spaced armour using plates of material and can therefore be used on lighter combat vehicles such as 4x4’s [37]. Ceramics offer superior resistance against kinetic energy penetrating projectiles by abrading the projectile as they penetrate but offer reduced protection when successive projectile hits are landed on the same area due to fracturing of the ceramic armour [35]. Sloping the armour results in poorer protection as a single projectile can affect a larger area than perpendicularly placed armour [38]. Some armour systems such as the British developed Chobham armour combine metallic and ceramic pieces to make use of the benefits of all the materials used. Chobham armour also has elastic layers placed in between the ceramic layers as a form of non-explosive reactive armour (NERA). NERA makes use of the penetrating projectile’s kinetic energy to compress and then expand an elastic material into the path of penetration [39]. The counterpart to NERA is ERA, explosive reactive armour. Whereas NERA makes use of an elastic material, ERA makes use of layers of high explosive in between the armour plates. When a projectile impacts the armour, the high explosive is set off. This produces a blast wave directly opposing the penetrating projectile and disrupts its path of penetration either via the blast wave or by moving armour plates [39]. All armour systems make use of spall liners to be installed on surfaces which interface which crew or equipment to prevent damage from debris created during projectile impacts. [40]. Hard kill systems are often used in combinations. The defence suite of a Russian BMPT-72 support fighting vehicle is illustrated in figure 7.

Figure 7: Armour Suite of a BMPT-72, image taken from: https://www.armyrecognition.com/russia_russian_army_light_armoured_vehicle_uk/bmpt72_terminator_2_tank_support_armoured_fighting_vehicle_technical_data_sheet_specifications.html

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Soft-kill Systems Soft-kill measures protect the vehicle by making it unable to be seen or targeted or by redirecting a projectile by deploying countermeasures. Aircraft most commonly make use of infrared flares countermeasures which lure infrared guided projectiles away. Flares are made of magnesium or other chemicals which become very hot or bright when combusted. This causes heat-guided projectiles to follow the decoy and not the aircraft [42]. A C-17 deploying flares is illustrated in figure 8.

Figure 8: C-17 Deploying Flares, image defense.com/media/military-flares-c17-globemaster.44/

taken

from:

https://world-

Projectiles can also be radar guided in which case chaff is used. Chaff is usually made of aluminium foil or aluminium -coated glass fibres so that the fibres are light and will float in air for as long as possible. The purpose of chaff is to reflect radar waves and in effect hide the radar signature of the vehicle in the same way a smoke screen would visually disguise a vehicle. [43]. There are also radio frequency countermeasures such as the BriteCloud expendable decoy which copy the radio frequency signature of the vehicle to lure projectiles away from it [44]. Naval and land-based vehicles make use of actual smoke screen countermeasures. Modern smoke screen countermeasures are made up of various chemicals which allow disruption of infrared and laser signatures and well and visually concealing the vehicle.

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1.3.8 Ordnance Alternatives Instead of considering different weapon systems to install on a UGCV, the calibre of the round shall be considered. This will allow anticipation of the round ballistic performance to determine the damage its capable of inflicting against various armour types and personnel. Once a suitable calibre has been chosen the weapon systems which can fire that calibre can be chosen. These weapon systems however are susceptible to regional availability and preference of the respective Departments of Defence and military. The armed UGCV’s discussed previously, Foster-Miller’s SWORDS and MAARS and BAE’s Black Knight all made use of 7,62mm light machine guns mounted on the vehicle turret. MAARS, being the successor to SWORDs also featured four 40mm M203 grenade launcher tubes to provide more versatility and firepower than SWORDS. Black Knight, being a much larger and heavier vehicle featured a 30mm main cannon which was supported by the 7,62mm machine gun.

The 7,62mm rifle round shall be considered first as the main armament calibre since it has been used by the UGCV’s considered so far. The 7,62x51mm was developed just after World War I as an alternative to the larger, more powerful rounds in use which produced harder handling of the rifles at the time [45]. The fully automatic and burst fire behaviour of the 7,62x51mm round made the firearm hard to control. This was dealt with by compromising with the smaller 5,56x45mm round. The 5,56mm round offers superior penetration past 600m in thin metal plates when compared with the 7,62mm round when fired from the same assault rifle [46]. The smaller round size and weight allows for more ammunition to be carried by soldiers and promotes faster time of flight with a flatter trajectory. Apart from these differences the smaller 5,56mm round offers similar performance to the 7,62mm round. These qualities made the 5,56x45 mm round the new standard assault rifle round [46].

Both rounds offer comparable performance, however the ability to incapacitate an enemy is based on the accuracy of the shooter and not the terminal ballistics. In the argument made by the chairman of NATO Weapons and Sensors Working Group, P. G. Arvidsson, incapacitating an enemy is achieved by damaging the central nervous system and through blood loss which is why shooters have to be well trained [46]. By extension, incapacitating a vehicle implies damaging vital mechanical components or the operating crew. There are many ways to incapacitate an enemy according to this definition. Firearms using pistol or shotgun rounds are both extensively used by militaries worldwide and for home defence. Weapons such as 17

grenades, rockets and high calibre firearms are primarily used against vehicles as these weapons are too large and create too much recoil to serve as general purpose weapons. Grenade launchers offer a barrel propelled counterpart to the traditional thrown grenade and can come in lethal and non-lethal variants such as high explosive, smoke, teargas and disorientating [47]. There are a variety of rocket systems available with the majority being mounted on vehicles for multiple launch capability. High calibre fire arms such as 0.50 rifles and anti-tank rifles are not usually used against infantry targets but rather as anti-vehicle and anti-material weapons [48].

1.3.9 Power Supply All the electrical equipment and locomotion systems of the UGCV require power to function. Smaller UGCV’s such as Packbot, SWORDS and Cutlass made use of electric motors to drive their track systems. These electrically driven UGCV’s drew their power from on board Lithium Ion batteries with supply voltages ranging from 12V to 46V [4][6][13][15] and had mission lives ranging from two hours to one week dependent on terrain and usage. These electrically driven UGCV’s were designed to be transportable by a person or by light vehicle. This meant that spare batteries could be readily supplied to the UGCV or it could be easily recovered if its batteries were completely discharged. Black Knight, being a vehicle based UGCV design was able to accommodate a 300 bhp diesel engine manufactured by Caterpillar to drive its track system [15]. The engine allows for on board batteries to be recharged as the vehicle operates, providing a longer mission life dependent on the vehicle’s fuel consumption. The power supply or storage system of the UGCV must be able to supply the vehicle with enough power that it can be deployed, operate without fault during the mission and move to a location for retrieval. The mission life of the UGCV can not be reliably estimated as there are many factors which could delay or assist the completion of a mission. For this reason, it is important to ensure that the UGCV can be recharged or refuelled either on its own or during the mission, if required.

1.3.10 Airdrop Procedures and Constraints The UGCV’s considered were small enough to be transportable by person or light vehicle, apart from Black Knight. Black Knight has a mass of 9 tonnes and requires airdrop from a heavy cargo plane such as the Lockheed C-130. Air drop or airlifting of military vehicles, supplies or equipment can be done in several ways. All these methods involve a cargo aircraft and can either be executed by an operator pushing the cargo out, a parachute being deployed 18

to pull the load out of the aircraft or the use of gravity to slide the load out. Air drops can be made at high or low speed and at high or low altitudes. These factors are determined by the safety of the airspace, the available space for the aircraft and the fragility of the load being delivered. Fixed wing aircraft are used for long distance airdrops as they are designed to operate at higher altitudes and over longer ranges. Traditionally airdrops of vehicles are not directly to battle zones but rather to air bases. This is also not done via parachute as the vehicles are often too heavy to feasibly be deployed by parachute. The other reason is that often, the size of the vehicles mean that they must be disassembled to be airlifted and must be reassembled once delivered so that it can be combat ready. Lighter vehicles such as the U.S. military’s High Mobility Multipurpose Wheeled Vehicles (HMMWV’s) or Humvees are airdropped as part of training missions. Air dropping these vehicles can only be performed by C-17 Globemaster II and C-130 Super Hercules aircraft due to the dimensions of the vehicles [49]. A 4-litter ambulance weighs approximately 3,57 tonnes and the maximum payloads of the C-17 and C130 are 75 tonnes [50] and 20 tonnes [51] respectively, so both aircraft are capable of carrying more vehicles. The C-17 has cargo bay dimensions of 26m length x 5m width x 3m height [52] and the C-130 has cargo bay dimensions of 16m in length x 3m width x 2,7m height [17]. The airdrop of Humvees will be used as the procedural model for airdropping a UGCV as the mass of a vehicle sized UGCV is comparable. The Humvee is first packaged on a platform and padded with honeycomb. The honeycomb installed on the platform is designed to be crushed on landing to cushion the vehicle. The platform is then fitted with parachutes according to FM 4-20.102: Rigging Airdrop Platforms. Once the parachute systems are installed, the platform is loaded into the C-17. To drop the platform from the plane, the loadmaster deploys a drogue parachute which pulls out the extraction parachute. The extraction parachute pulls the platform out of the aircraft’s cargo bay and into freefall. The primary chutes deploy and the vehicle lands [53]. The sequence of event during an airdrop is illustrated in figure 9.

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Figure 9: Sequence of Events During an Air Drop, image taken from: https://www.quora.com/Can-a-mainbattle-tank-be-airdropped-and-be-operational-immediately-after-it-lands

Another form of an airdrop is airlifting via helicopter. Externally slung vehicles can be airlifted over lower flight ranges for tactical delivery of cargo such as troops, equipment or light vehicles. Helicopters such as the Sikorsky CH-53K ‘King Stallion’ and the Sikorsky UH-60 ‘Black Hawk’ are used by the U.S. military as multirole, heavy lift capability aircraft. These vehicles are used for the tactical airlifting of light vehicles and equipment. The Ch-53K has a sling payload of 12,2 tonnes and payload cabin dimensions of 9,1m long x 2m wide x 2m high [54]. The UH-60 has a sling payload of 3,6 tonnes [55]. Both vehicles are capable of airlifting light multipurpose vehicles such as the Humvee and therefore have the capability of airlifting UGCV’s of equivalent masses. An American HMMWV being airlifted via sling by a CH-53 is illustrated in figure 10.

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Figure 11: A CH-35 Airlifting a Light Armoured Vehicle, image taken from: http://www.wikiwand.com/en/Sikorsky_CH-53E_Super_Stallion

The C-130J Pocket Guide [17] page 9 lists a competitive survey of cargo planes and compares their cargo capacity in terms of 463L pallets among other objects. This survey is illustrated in figure 11.

Figure 10: Competitive Cargo Loads in Terms of No. of 463L Pallets [17]

Where each 463L pallet has base dimensions of 0,224m width and 0,274m in length. Picture of. The Airbus A400M has a maximum cargo payload of 37 tonnes with cargo bay dimensions of 17,7m in length, 4m in width and 4m in height [56]

1.4 Task as Understood With all these vehicle and system aspects to consider, the task as understood can be described as follows: it is required to design a mobile combat system which can be remote controlled globally and locally which can operate in modern combat environments, particularly urban areas with the ability to operate for as long as the mission requires. The system must be able to 21

withstand attack from rifle fire, grenades and projectile shaped charges using active and passive defence systems. The system must also obey all commands within a short time frame and provide the operator with enough environmental detail that the operator can maintain environmental awareness and make informed decisions. The vehicle must be capable of incapacitating personnel and lightly armoured vehicles effectively.

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2. User Requirement Specification (URS) The User Requirement Specification is to ensure that the vehicle can provide competitive operating characteristics with on-the-market solutions. It also guides the design of the vehicle to ensure that it can be included into existing military procedures and systems. These considerations include standard fuels used for vehicles and electrical equipment which can interface with as much of the existing and new technology used by the military as possible. The points in the URS are derived from the aspects and design considerations covered in the Literature Review.

2.1.1 Requirements •