Micro Air VehiclesMicro Air Vehicles

Dr. S. S. GokhaleNIT-Calicut

100 years ago100 years ago

1903-First Flight, Wright Brothers

12 hp Engine + Pusher Propeller & 318 kg Biplane

12 second flight, 120 ft distance & 10 ft altitude

MustangMustang

Jump Jet HarrierJump Jet Harrier

Civilian Objectives & GoalsCivilian Objectives & Goals

Higher, Faster, Longer Distances, - Personal Thrill

Cheaper, Safer, Reliable – Passenger Comforts

Economical, Easy to Maintain, Spare Part Access, Hanger/Runway Restrictions – Airline Operators

Familiar Layout, Less Retraining – Pilots, Crew

Military Objectives & GoalsMilitary Objectives & Goals

Speed, Maneuverability, Assorted Devastating Payload, Stealth ness

Ergonomic and Human Factors associated with Pilot- Blackout, Redout in High g Environment, Oxygen Mask, Ejection Seat etc.

Inherently unstable system requiring higher level of flying skill

Civilian- Boeing -777Civilian- Boeing -777

Passenger 300+ Cargo 150 cu m Fuel 195 kL TO Wt. 340 T Range 16400 km M 0.84, Alt. 10.7 km (LxWxD) 64x65x6.2

m Engine 2 x 50 T 18 hr flight

Military- B-2 StealthMilitary- B-2 Stealth

TO Wt. 150 T Payload 18 T Engine 4 x 7.8 T High Subsonic

Cruise, 15 km Alt. Range 9600 km (LxWxH) 21x52x5 m Low Operability Multi Role Bomber

Military- Raptor F-22Military- Raptor F-22

Air-Dominance Fighter

(LxWxH) 19x13.4x4.8 m

Mach 2 Sustainable Engines 2 F119 PW-

100 TF Engines with ~ 16 T thrust

Projected Date of Operation 2005

Century in Perspective Century in Perspective Strength Weakness Opportunit

yThreat

I Quarter CuriosityChallenge

In-depth KnowledgeMtl./Manuf.Engine Power

Military Applications

Jealousy

II Quarter Race for SupremacyResearch

Mtl./Limited IC Engine Power/Propeller

MilitaryGT EngineCommercial?

SuspicionSecrecy

III Quarter CommercialCompositesComputers

Relative War Free Period

Cutting Edge TechnologySpace Race

Espionage

IV Quarter Customer FocusIT, Biotech

Uni-polar World

GlobalizationVast Array of a/c

Cut Throat Competition

Birds and BeesBirds and Bees

Bird’s 3 Basic Motion Flapping-Tilting Lift

forward for Thrust Twisting TE-Adjust

Angle of Attack for Optimum Lift

Folding-Wing span Variation for Minimum Drag

Unsteady Flow-More Lift + Acceleration

Insect with Four Equal Sized Wings

Flapping is out of Phase between the Front and the Rear

Wings- Foldable underneath when not in use

High Amplitude, High Frequency Oscillations

Man v/s Bird – No Man v/s Bird – No ComparisonComparison

Man’s arm has 29 bones

It is a complex structure meant for dexterity & can perform skill jobs

It has reasonably poor strength

Birds arm has only 11 bones which are much longer and are fused together.

These are much simpler with fewer joints involving fewer movements & hence rigid.

Stronger wings provide Lift + Thrust

BirdsBirds

Perfectly controlled natural flying machine (8600 species)

Feathers: Light strong, flexible

Two legs: Hopping & Claws Difficult Landing

Adaptive: Body Organs Internalized

Bustard: 10kg/1.2 m W Falcon: 160-320 kmph

Wing ShapeWing Shape

Feathers give peculiar shape to the wings. The form & function of the same is directly correlated.

Birds which fly fast in open air have long narrow wings. These birds experience difficulty during take-off but have long sustaining power. Wing flapping between 60-100 times in an hour depending on calm or rough weather.

Woodland birds fly slowly but are extremely maneuverable. These birds have short broad wings with wide feathers.

Marvin Minsky developed the Tentacle Arm, which moved like an octopus. It had twelve joints designed to reach around obstacles. A PDP-6 computer controlled the arm, powered by hydraulic fluids. Mounted on a wall, it could lift the weight of a person.

Large InsectsLarge Insects

Flapping 100~1000/s Flapping: up/down &

forward/backward Thorax power sources

for wings & legs Skeleton provides

weather protection Ultra-light wing

structure Static Hovering

Hummingbirds are quite small with a length of only 2 ¼ in to 8 ½ in, however, they are not the smallest of all birds. They eat the nectar of flowers for survival and can consume up to half their weight in sugar daily. The reason for this enormous appetite is the hummingbird’s extraordinary flight capability.

The disadvantage of hovering is the excessive energy required for its success. The excessive energy requires the hummingbird to consume a lot of food. The energy output of a hummingbird in hovering flight is ten times as much as a man running nine miles an hour. Direct comparisons to a human being show that a 170-pound man would have to consume about 130 pounds of bread to keep up with a hummingbird’s energy-output

University of Texas Project to Study Hummingbird - MAV

Figure "8" motif the wingtips of the hummingbird trace in the air while hovering, as well as the wing patterns at various positions. Notice the change in the pitch attitude of the hummingbird as the speed of the bird changes from top speed to hovering.

Basic Equipment used in research: HS Camera, CT Scanner, Frame grabber, MSC/NASTRAN Software, Computer, Photo-Imaging Tools, Aero-elastic Analysis

At the sizes envisioned for these devices, normal aerodynamic rules no longer apply. Micro-flyers will have to operate in an environment more common to small birds and large insects than that of larger aircraft. The forces associated with air moving around the tiny devices are more pronounced than with conventional aircraft in flight, causing increased drag, reduced lift under the smaller wings at low speeds, and decreased propeller efficiency. Such aircraft, weighing only 50 grams, are more susceptible to wind gusts, updrafts, and rain. Other challenges include developing tiny sensors, engines, and power sources for such planes, as well as communications, control and navigation systems for the tiny robot aircraft, which would have to operate with little or no human input. Micro-flyers require an entirely new approach to aircraft design and miniaturization. As flying objects become smaller, the viscosity of the air becomes increasingly important because for the smallest insects, flying is more like swimming through honey. Micro-wings are also susceptible to boundary layer separation. Small changes in the angle of flight can result in extreme loss of lift

Flight BasicFlight Basic

Weight: Gravity - Default

Thrust: Machine / Muscle Power

Lift & Drag: Aerodynamic forces due to Motion

Level & Un accelerated Flight: L = W and T = D

Flight Control due to unbalanced forces

L/D and T/WL/D and T/W

L/D T/W

Birds/Insects ~ 20 ~ 0.2 - 0.3

Gliders ~ 20-35 0

Aircraft ~ 15-20 (commercial)

~ 4-10 (military)

~ 0.2 - 0.3

~ 1.2 - 6

Human Powered FlightHuman Powered Flight

Paul McCready June 79

English Channel Crossing- 22 miles in 2 hrs 49 min (12.5 kmph)

31 m Wing-Span and 31.5 kg weight

50000 UKP Kramer Competition

500 m equilateral triangle clock and anticlockwise in 7 minutes

Flt. Speed 10 m/s, Altitude 5 m in a wind speed of 5 m/s at 10 m Alt.

RPV & UAVRPV & UAV Tactical Reconnaissance

& Surveillance, Missile Simulation

2 Stroke, 4 Cylinder, 24 hp engine + Carbon Propeller or Turbojet

(WxLxH) 2.6x3x2.2 m TO 75 kg, Payload 20 kg,

CCD Camera Max Speed 320 kmph Cruise 80 kmph Alt. 3km, 50 km Radius Guidance Remote+GPS

RPV & UAVRPV & UAV

Airborne Experiments Wing 1.75 m Wing Area 0.52 sq m Weight ~ 3 kg Cargo 1.4x3x1.2 cm 200 g fuel, 1.15 L, 1

hp, 2 cycle engine 72 MHz FM

Transmitter/ Receiver Video Camera

Autonomous Helicopter Autonomous Helicopter ApplicationsApplications

Search and Rescue

Quick and Systematic Search

Lock Position and follow it up

Autonomous Helicopter Autonomous Helicopter ApplicationsApplications

Surveillance Patrol Area for

Unusual Activity Day & Night

Operations

Autonomous Helicopter Autonomous Helicopter ApplicationsApplications

Law Enforcement High Speed Chase Assistance to

Police

Autonomous Helicopter Autonomous Helicopter ApplicationsApplications

Aerial Mapping More Accurate

Topological Map Altitude v/s Area

of Coverage v/s Resolution

Autonomous Helicopter Autonomous Helicopter ApplicationsApplications

Cinematography Entertainment

MAV Design PhilosophyMAV Design Philosophy

Robots with High Level of AutonomyMinimum External Resource

DependenceMount System Power, Sensors,

Controls, Computers on BoardChoice Driven by Weight, Cost,

Power ConsumptionBehavior based Control Approach

MAV Goal MissionMAV Goal Mission

Auto Start and Take OffFly to designated Area on Prescribed

Path Avoiding ObstaclesLock on Target and PursueSend Information, Images back

HomeSafe LandingAll Weather Flying Capability

MAV- Main CharacteristicsMAV- Main Characteristics(L / W / H) – Not to Exceed 15 cmWeight 50 g, Payload 20 gSpeed 35-75 kmphCruise Altitude 70 – 100 mRange 10 kmFlight Duration 20 – 60 minutesSix Degree Freedom Aerial Robots

Technology FeasibilityTechnology Feasibility

Micro-ElectroMechanical Systems (MEMS)

Integrated Multifunctional System-Sensors, Actuators, Micro-processors

Micro-fabrication TechniquesLow-Cost Production PotentialFast Processors, Smaller Storage

Devices

Innovative Solution Innovative Solution NeededNeeded

AerodynamicsControlPropulsion and PowerNavigationCommunicationSmart Structures

AerodynamicsAerodynamics

Reynolds Number = ( u L) /, Limited knowledge at Low Re

Low AR- 3-D Effects Agility, Range, Flt. Dyn.

Observations for Bird, Insect Limited

Mechanizing flight at low Re Difficult

Unconventional Wings and Movement

Rotary WingRotary Wing

Low Speed & Hovering Capabilities

Possible use in Data Collection on Mars Mission

Easily Scalable Useful in studying

Wind-Shear

Flapping WingFlapping Wing

Imitating Birds Induced Vortex

Generation Electric Impulse

to Elastomer Actuators causes Contraction and Relaxation

Adaptive Wings

Reconnaissance MissionReconnaissance Mission

Situation Awareness at platoon Level

Real Time Day-Night Imagery

MAV Relocating at Vantage Points

Unattended surface sensors from Imagery to Seismic Detection

Urban Operation MissionUrban Operation Mission

Reconnaissance and Surveillance of Inner City Areas

Ability to Navigate Complex Shaped Passages

Avoid Obstacles Relay Information

back to Manage Urban Disaster / Terrorism

Biochemical SensingBiochemical Sensing

Gradient Sensors and Flight Control Feedback to Map Size of Hazardous Clouds

Provide Real Time Tracking Information

MAV ApplicationsMAV Applications

Packed with Ejector Seat Mechanism of Aircraft-Sends Signals about Downed Pilot

MAV could be used for Traffic Monitoring, Border Surveillance, Fire and Rescue Operations, Forestry, Wild-Life Survey, Power Line Inspection, Aerial Photography

MAV can Provide targeting Information & Battle Damage Assessment

Barrel or Overhead Flight Vehicle Launch is Possible

MAV System IntegrationMAV System Integration MEMS based

Components Individual Components

Occupy More Space On-board Processor &

Communication Electronics- MAV Core

Critical Link between Major Subsystems is Important

Multifunctional use & Synergy is Crucial

PropulsionPropulsion

Low Re -> L/D~1/3-1/4 -> Need More Power

Small Propellers have Poor Efficiency

Realized Power is Less

Higher Energy Density is Necessary

Battery Technology -> Fuel Cell Use

MAV Control Guidance MAV Control Guidance CommunicationCommunication

Current GPS is Too Heavy and Power Intensive

Human Responses for Enhanced Agility are Slow

Miniaturized and Advanced Navigation, Guidance and Control need to be Developed

MAV PayloadMAV Payload

Sensors-Optical,, IR, Acoustic, Bio-chemical, Nuclear

Visible Imaging System-1 cu cm Camera Weighing 1 g with 1000x1000 pixels and requiring 0.25 milliwatt power

Mature Technology is Available

MIT Concept of MAVMIT Concept of MAV

8 cm vehicle with 10 g weight & total power requirement of 1 watt

Propulsion needs 90% of Total Power and takes 70% of Total Weight

Forward mounted Video System looking down at 45 degree at 2 frames/s

Smart Structure: EntomopterSmart Structure: Entomopter

Mechanical Insect Reciprocating Chemical

Muscle (RCM) Generating autonomic

wing beating from a chemical energy source Adaptive Wing Concept

Self Repairing Structures & Nano- Technology

Through direct conversion, RCM provides small amounts of electricity for onboard systems

Robert Michelson, Georgia Tech Research Institute

Weight IssuesWeight Issues

Small Size -> High Surface to Volume Ratio

Constraints on Weight and Volume

Develop and Integrate Physical Elements & Components

Multifunctional amongst System Components

Presently, work is progressing to develop the wings for the Mars Entomopter. Stereo-lithography and Fused Deposition Modeling techniques have allowed Michelson's design team to create intricate wing structures directly from computer models. Careful attention is being paid to material selection. Resilience, stiffness in opposite planes, chemical compatibility, and ease of bonding are but a few of the points to be considered in choosing wing materials. Wings have been grown in our stereo-lithography machines as well as ABS wing stiffening structures produced using Fused Deposition Modeling (FDM) methods with, and without interstitial materials. The interstitial material has been placed over the flexible wing structure to demonstrate that micro-channel ribs can be produced to create a wing that can distribute gas to portions of the wing for active flow control to increase lift and produce attitude control moments. Later wing designs are greatly simplified with a single "spar channel" encased in a composite thin wing.

Researchers from the Departments of Aerospace & Mechanical Engineering and Electrical & Computer Engineering at the University of Florida are doing on-going work on vision-guided autonomous flight for Micro Air Vehicles (MAVs).

Indian EffortsIndian Efforts

Indians involved in Research in MAV in USA (MIT, Georgia etc.)

NAL, IISc, IITs carrying out Elementary Experimental and Simulation Work

Commitment from Raksha Mantralaya as a Priority Area

Lot more needs to be done Rudimentary MEMS Work Undertaken in

a Few places

Flow past two impulsively started cylinders at Re=550 (15 seconds).Ph.D. Work of Prabhu Ramachandran, Dept. of ASE, IIT-Madras.

IIT-M Efforts: CFD SimulationIIT-M Efforts: CFD Simulation

5 degrees

10 degrees

15 degrees

Flow Past Flat Plate at an Angle of Attack (Re=1000). Simulation time 10s.

Ph.D. Work of Prabhu Ramachandran, Dept. of ASE, IIT-Madras

Flow past an oscillating flat plate. Work done at Cal. Tech.

Concept - Using thermoelectric generator modules to convert Concept - Using thermoelectric generator modules to convert engine waste heat energy to useful electric energy for micro engine waste heat energy to useful electric energy for micro

air vehicles air vehicles Result - An enabling technology for extending the endurance Result - An enabling technology for extending the endurance

and mission capabilities of micro air vehicles.and mission capabilities of micro air vehicles.Fleming, J. L., Ng, W. F., and Ghamaty, S., "Thermoelectric-Fleming, J. L., Ng, W. F., and Ghamaty, S., "Thermoelectric-

Based Power System for UAV/MAV Applications", AIAA Paper Based Power System for UAV/MAV Applications", AIAA Paper 2002-3412, Unmanned Aerospace Vehicles, Systems, 2002-3412, Unmanned Aerospace Vehicles, Systems,

Technologies, and Operations Conference and Workshop, Technologies, and Operations Conference and Workshop, Portsmouth, VA, May 20-23, 2002.Portsmouth, VA, May 20-23, 2002.

Small Is Beautiful