unmanned aerial vehicle competition auvsi aerial vehicle competition auvsi team members: viurniel...

Unmanned Aerial Vehicle Competition

AUVSI

Team Members:

Viurniel Sanchez

Hassan Chaudary

Esam Mashni

Nicolas Norena

Seyed Maysam Alavi

Ana Puente

Natalia Alejandra Posada

Javier Villareal

Advisor:

Professor Ibrahim Tansel

May 23, 2011

AEROBOTS@FIU 2011- AUVSI

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Abstract— In its present form this journal is a result of investigation, design and tests into electric unmanned aerial systems for the AUVSI SUAS competition with prolonged flight capabilities. Additional investigation and testing in the field of remotely operated planes and off the shelf (OTS) vehicles led to an array of challenges within the current unmanned aerial vehicle systems of which flight duration, precise data acquisition, and systems integration was prominent. In lieu of a grand variety of UAV platforms in the market the UAV aircraft design was focused on developing a light weight and sturdy electric aircraft with autonomous target acquisition capabilities, and safe operation high performance OTS control systems. This journal will provide a detailed overview of the expected mission (as tested at FIU), challenges, current developments, design and growth potential of the system integration of our custom aircraft and OTS control systems with flight time capabilities that exceed 20 minutes. The report will concisely detail the design, manufacturing and testing process used by the team in preparation for the AUVSI SUAS 2011 Competition.

Manuscript received May 18, 2011. This work was supported in part by the ARC, the MME Department, CSO, and SGA at Florida International University, The Florida Space Grant Consortium, and by Dr. Tansel Associate Professor at FIU.

Viurniel is an Electrical Engineer student at Florida International University, Miami, FL; email: [email protected]

Esam is an Electrical Engineer student at Florida International University, Miami, FL; email: [email protected]

Nicolas is a Computer Engineer student at Florida International University, Miami, FL; email: [email protected]

Natalia is an Mechanical Engineer student at Florida International University, Miami, FL; email: [email protected]

Ana is Mecanical Engineer student at Florida International University, Miami, FL; email: [email protected]

Hassan is an Electrical Engineer student at Florida International University, Miami, FL; email: [email protected]

Seyed is an Mechanical Engineer student at Florida International University, Miami, FL; email: [email protected]

Javier is Mecanical Engineer student at Florida International University, Miami, FL; email: [email protected]

I. INTRODUCTION

HE AEROBOTS@FIU team is an interdisciplinary group of Electrical, Mechanical, and Computer

Engineer Students. The design of an electric stable and long lasting unmanned aerial vehicle capable of intelligence, surveillance and reconnaissance has been accomplished. In order to design and build a high performance UAV with such capabilities the design team was first aimed for preliminary feasible goals such as medium level maneuverability and high stability. We also emphasized on the design of the internal spacing in the fuselage to securely sustain the electrical systems on board the UAV. The autopilot onboard has been optimized for total autonomy, including autonomous takeoff and landing, with the inclusion of a sonar system. Furthermore, we have arduously worked in the integration of target recognition software needed for mission completion.

A. Team Roles

Title Name Faculty Advisor Dr. Tansel Programming Leader Nicholas Norena Aerodynamics Leader Seyed Alavi Structure Leader Ana Puente Propulsion Leader Esam Mashni Communications Leader Hassan Chaudary Autopilot Leader Viurniel Sanchez Logistics and Fundraising Natalia Posada Pilot (Top Gun) Javier Villareal

B. Project Formulation

a) Overview

The approach toward the UAV design includes primarily the selection of a high lift low Reynolds number airfoil in addition to light and

AEROBOTS@FIU AUVSI 2011

Viurniel Sanchez, Esam Mashni, Nicolas Norena, Hassan Chaudary, Ana Puente, Javier Villareal, Natalia Posada, Seyed Alavi

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sturdy materials as a means of prolonging flight duration. Upon selection of an appropriate high performance airfoil the control, propeller and reconnaissance devices are selected and sized since the bulk of the fuselage will be configured as to accommodate each component accordingly. The UAV configuration was implemented with safety as the highest priority. The structure and components selected were found to be reliable and trustworthy. The system was created with a human controlled fail-safe and a computer controlled secondary fail safe to ensure its reliability. The UAV has been successful in all of its pre-competition missions. The system shows long range reliability and very accurate waypoint navigation. It also accomplished autonomous landings and takeoffs.

Table 1: Design Metrics

Description Detail

Team Name aerobots@fiu

Mission Intelligence, Surveillance and Reconnaissance

Max Overall Length (cm) 180 centimeters

Max Overall Wing Span (cm)

182.88 centimeters

Max Projected Empty Weight (g)

2200 grams

Power plant Electric

Max Weight 6000grams

II. DESIGN AND CONSIDERATIONS

The conceptual Designs for the aircraft included considerations into the mechanical and electrical systems. The type of wing, the type of empennage, and wing placement that were best suit for our UAV were selected. A vast amount of research was also done to select the appropriate and best suited electrical systems.

Visual Aircraft Dimensions

A. Visual Aircraft Dimensions

Description Location

Dimensions-cm (Tol ± 1%)

Dimensions-inches

a Distance: Propeller to leading edge

~30 11.75

b Wing Span ~188 74 c Chord Length ~30 11.75 d Aileron Length ~7.5 3 e Aileron Width ~46 18 f Trailing edge to

empennage ~75 30

g Elevator area ~310 (cm2) 48in^2 Dihedral ~3°-5°

B. Airframe Design

a) Wing

A straight wing configuration was selected; it is a wing with no forward or backward inclination or angle. It has desirable features for a low speed high performance aircraft in terms of stability and duration. Another design consideration included the location of a wing. The main concern included a configuration that would permit a camera mounting bracket with sufficient clearance and stability. Preliminary observations deemed the top wing configuration the most viable since it provides the least interference with camera additions to the fuselage.

b) Fuselage

The fuselage is the section of the unmanned aerial vehicle for which the principal payload includes the power plant, power generation component, reconnaissance devices and the autopilot system. The primary objective was to utilize a fuselage with reduced aerodynamic drag, maximum aerodynamic stability and sufficient space to accommodate efficiently the electrical components. Furthermore, the structural design was configured to save weight while including protection against fatigue and corrosion.

The space inside of the fuselage had to be large enough to house a significant number of different auxiliary power units such as the camera, autopilot, electrical peripherals, etc. Also, the space is ample enough for ease of payload arrangements in assembly and disassembly.


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OpenFoam Result of 3D coarse mesh around fuselage

Solidworks simulation around fuselage The first figure above is a 3D representation of the external

incompressible viscous flow going around the fuselage. The pressures are color coded to represent highest pressure concentrations, in the red regions, and the lowest concentrations, in the dark blue regions. As expected the highest concentration of pressure occurred at the leading edge of the fuselage with a pressure of 101.45 kPa. The cut in the rear of the fuselage aims at streamlining the fuselage in order to lower the turbulent flow and reduce the drag. Therefore, the fuselage shows a decrease in pressure, represented by the light blue color.

C. Power & Electrical Systems

The power system aboard the UAV consists of three components; the motor, the electronic speed controller (ESC), and the batteries. The motor is a very large brushless out runner motor with huge torque and can pull up to 10kg. The ESC is built with imported N-Channel mosFETs and an ultra-fast Atmel MCU & heartbeat make this a high performance ESC with excellent sync capabilities. This ESC has a 5A SBEC for solid reliable servo power. It is programmable via an R/C controller to allow you to program all functions to fit your specific needs, which makes it efficient and user friendly. It has been placed in a manner that constant airflow will maintain its temperature significantly low. The batteries are two Rhino

4900mAh 3S1P 11.1v 20C Li-poly Pack, which provide tested flight duration of over 40 minutes on a single charge. They are yellow, which allows them to be located with ease in case of emergency.

On our ground station all system components are fed from a 110/120 V power supply, and transformers will decrease the voltage as required by each component.

The electrical systems selected were done on the basis of optimization. We have three systems that make our mission possible; video system, autopilot system, and RC transceiver. We selected a system, the “mother of all AEROBOTS” that could integrate our 3 systems as sub-systems.

D. Aircraft Components Layout

III. ELECTRICAL SYSTEMS (ON-BOARD)

The UAV requires gyroscopes, a camera, sensors, and GPS. The sensors and GPS, however, have been integrated within the autopilot system. All these electrical components are vital for successful mission completion. The gyros function will be to keep the plane calibrated while in flight; the sensors are needed in order to evaluate the internal integrated system within the UAV such as the speed and height by measuring barometric pressure.

A. Micropilot 2028g

Micro pilot Receiver

Battery Battery


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The MicroPilot Autopilot is the perfect choice to stabilize and guide a wide range of UAVs, from highly functional high speed UAVs through backpack UAVs to handheld micro UAVs. The MicroPilot Autopilot is the only micro UAV autopilot designed for fully autonomous operation —from launch through recovery. Capabilities include airspeed hold, altitude hold, turn coordination, GPS navigation as well as autonomous launch and recovery. Extensive data logging and manual overrides are also supported, as is a highly functional command buffer. All feedback loop gains and flight parameters are user programmable and feedback loops are adjustable in flight. The MicroPilot Autopilot also includes the HORIZONmp ground control software for mission creation, parameter adjustment, flight monitoring and mission simulation.

1) Micropilot Features • Altitude hold, airspeed hold, and GPS waypoint navigation • 1,000 programmable waypoints or commands • Fully integrated—all sensors required for complete airframe stabilization are integrated into a single circuit board • Complete autonomous operation from launch to recovery • Autonomous launch methods include runway takeoff, hand launch, bungee launch, and catapult launch • Autonomous recovery methods include runway landing, parachute recovery, and deep stall landing • Supports manually directed and autonomous flight modes, as well as an integrated RC override • Extensive data log capability simplifies post flight diagnostics and analysis • Integrated POST ensures reliability and repeatability • Low battery warnings, both on the ground and in flight • User programmable error handlers for loss of GPS signal, loss of RC signal, engine failure, loss of data link, and low battery voltage • Extremely low 28 gram weight is suitable for micro UAVs • Feedback loop gains are adjustable while in flight

2) Component Dimensions and Weights • MP2028g CORE

38 mm by 101 mm by18 mm, (28g)

• MP2028g AGL (AGL sensor) 40 by 38 by 15 mm, (18 g)

• MP-SERVO(servo expansion board) 31 by 48 by 13 mm, (6 g)

• MP-ANT(GPS antenna) 34 y 25 by 10 mm, (32 g)

3) Micropilot Power

Power is supplied to the MicroPilot Autopilot on P2. Servo power is supplied directly to the servo board. It was important to provide separate power sources for the MicroPilot Autopilot and the servos. This is due to the servos sometimes drawing large amounts of current for short periods of time. These large current draws can cause a voltage drop in the power source and the Autopilot could stall.

4) Ground Loops It was very important to ensure that there were no

ground loops within your wiring harness, where the return current flows through the MP2028g . It was best to avoid ground loops in any event, as they can introduce noise into the system. We avoided having to power the electronic speed controller from the same battery pack as the autopilot, because ground loops could be created by the speed controller’s throttle servo input, or by the use of a BEC connection.


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5) RC Receiver The RC receiver is connected via a standard plug

to P2. The RC Transmitter does not use mixing as all of the servo mixing is performed by the autopilot.

6) Servo Board

The MicroPilot Autopilot uses a separate circuit board

to distribute the servo signals to each servo. Each servo board can accommodate up to 8servos and 3 servo boards can be connected to the MicroPilot Autopilot. The 8 servo connectors are labeled S1 through S8. Power is supplied to the servos via J1 at the top of the board. Pins 1 and 2 of J1 are ground, pins 3 and 4 are unregulated power and pins 5 and 6 are not connected. Two pins are provided for power and ground so that power can be routed to additional servo boards in a daisy chain fashion. Each servo board can supply a maximum of 3 Amps, equally distributed among the output connectors. This limit is due to the pin capacity of the J1 connector. If two power and two ground pins are used on J1 to supply power, the servo board can supply up to 4 Amps. The control signals can drive a maximum of 25mA per output pin.

7) GPS The MicroPilot Autopilot includes an integrated

GPS receiver using the Trimble TSIP protocol. An external GPS antenna is required and is connected to the coaxial cable attached to the MicroPilot Autopilot. The antenna was connected directly to the MicroPilot Autopilot by the means of a short adapter cable included with the standard MicroPilot Autopilot. Where and how one mounts the GPS antenna will affect the operation of the GPS. We followed these guidelines to improve performance:

• Installed a ground plane. Installing a ground plane improved signal reception and GPS performance. This was accomplished by using a copper sheet, 4 by 4 inches that provided good electrical contact with the antenna. • Avoided obstructions. GPS signals are weak and even small obstructions will degrade the signal. • Mounted the antenna away from the engine. Mounting the antenna too close to the engine will increase vibration and possibly subject the antenna to fuel contamination. • Avoided sources of RF interference. GPS signals are very susceptible to RF interference from devices such as radio modems, RF transmitters, and video transmitters. When one uses these devices, one has to check that they do not degrade the GPS signal. They may not block the GPS signal entirely but they can degrade the signal enough to increase the chances of the GPS being lost in flight. If the GPS signal is degraded, the GPS receiver will take longer to lock.

8) AGL Module The AGL board is an optional ultrasonic altimeter

that provides high resolution altitude information up to an altitude of 16 feet above the ground. It is required for autonomous runway takeoff and landing. The AGL board is connected to the P2 connector on the MicroPilot. By default, the MicroPilot Autopilot expects an AGL board. The AGL transducer was mounted facing down, on the wing tip as far from the engine as possible. (The transducer is very susceptible to engine noise.) It is mounted at least 8 inches above the ground when the plane is sitting on the ground. We made sure there were no obstructions between the sensor and the ground. The cable between the transducer and the board is a shielded coaxial cable.

9) PITOT tube


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The airspeed pressure transducer on the MicroPilot Autopilot board must be connected to an external pitot tube to measure dynamic air pressure. A 1/8 or 3/16 inch i.d. brass tube was mounted to the underside of the wing, far enough out on the wing to be clear of the prop wash. Then, a piece of silicon fuel line was ran from the brass tube to the airspeed pressure transducer on the autopilot. The static air inlet on the MP2028g is built-in to the underside of the airspeed pressure transducer, next to the circuit board. The MP2028g must therefore be exposed to atmospheric pressure to ensure reliable airspeed reporting.

B. Motor & Propeller

The Motor and Propeller selection is based on various parameters namely the amount of thrust required by the aircraft, the amount of clearance from the nose of the aircraft to the ground, ambient temperature, expected flight altitudes, and projected lift to drag ratios. Specifically in the case of the motor selection it was important to obtain a motor with sufficient takeoff power to lift the UAV platform and maintain it in level cruise flight.

Equation for Statistical Estimation of Horsepower to Weight Ratio relationship:

This equation represents a statistical calculation

which permits a theoretical estimation of the horsepower to weight relationship based on typical class of aircrafts designed for efficiency during cruising. The table below displays the calculated take-off and cruise velocity values used to calculation the minimum horsepower to weight ratios.

Specifications and Performance Predictions

Parameter Value

Wing Area 0.561 m2

Aspect Ratio 6.3 Wing Loading 93.98 N/S

Take-off velocity 14.86 m/s

Cruise velocity 12.39 m/s

Stall Velocity 3.65 m/s

Table: Velocity Considerations

Velocity Considerations m/s

Take-off Velocity 14.8

Cruise Velocity 12.9

Values “a” and “c” represent calibration coefficients which vary based on the material of the aircraft and are only valid for aircrafts designed for average cruise speeds.

The following table displays the resulting

minimum power requirements for take-off and cruising in units of horsepower and watts. The values are calculated taking into consideration the expected lift to drag ratio, cruise velocity, average takeoff horsepower, average cruise horsepower and expected weight.

Table: Take-off parameters Results Values Minimum take-off (hp/W) ratio 0.361044 Minimum take-off (hp) 0.095196 Minimum take-off power (Watts) 70.98736

Since an electric system will be utilized instead of

a fuel powered system the expected takeoff weight and cruising weight is equal and thus its ratio goes to 1 as shown in the following equation.

Equation: Horsepower to Weight ratio


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In general a large diameter propeller has better efficiency overall. Still there are a few limiting factors such as tip speed and ground clearance. The aircrafts forward speed based on the propeller is calculated by equation 20 in which n represent the rotational rate (rpm) and d represents the diameter of the propeller.

Equation: Aircraft forward speed calculation

Typical propeller efficiency is 0.8 ). It should be noted that since the inner diameter of the prop provides little thrust and thus a guiding cone (spinner) as seen in figure ## which pushes the air toward more productive sections of the propeller will be utilized as a tool to increase the efficiency of the propeller.

Estimated 2-blade propeller diameter in terms of

horsepower suggests a minimum propeller diameter of 12 inches. We found the optimal size to be 16x9.

Image: Spinner

C. Servos and Servo Board

We choose Hitec HS-65 in a new digital version. The HS-5065MG High Performance Micro Servo features Hitec's digital, programmable circuit for incredible resolution, centering and holding torque; also featuring metal gears, a top-ball bearing, and at 31 oz./in. of torque and has a quick transit time of 0.11 sec at 6 volts.

Servo Specifications Motor Type: 3 Pole Bearing Type: Top Ball Bearing Speed (4.8V/6.0V): 0.14 / 0.11 Torque oz./in. 25 / 31

(4.8V/6.0V): Torque kg./cm.

(4.8V/6.0V): 1.8 / 2.2

Size in Inches: 0.92 x 0.45 x 0.94

Size in Millimeters: 23.37 x 11.43 x

23.88 Weight ounces: 0.42 Weight grams: 11.91

D. Electronic Speed Controller

The ESC selected exhibits extremely low internal resistance, along with super smooth and accurate throttle linearity. It is pre-programmed for over heat and over-load protection. The system will Auto shutdown when signal is lost or radio interference becomes severe for more than 2 seconds. It supports high RPM motors. It has power arming protection (prevents the motor from accidentally running when switched ON) Advanced programming software.

Programming features of the ESC: • Brake setting • Battery type(LiPo or NiCd/NiMh) • Low voltage cutoff setting • Factory default setup restore • Timing settings (to enhance ESC efficiency

and smoothness) • Motor rotation( clockwise\counterclockwise)

Switching frequency • Low voltage cutoff type (power reduction or

immediate shutdown)

E. RC Receiver

The AR7000 combines an internal and remote receiver, offering superior path diversity. The radio system simultaneously transmits on two frequencies, creating dual RF paths. This dual path redundancy, plus the fact each of the two receivers is located in a slightly different location, exposes each to a different RF environment and creates a bulletproof RF link in all conditions. The AR7000 is Flight Log compatible with the SPM9540, which is also part of our system. Key Features

• 7 channels • Includes patented MultiLink redundant

receiver technology


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• Utilizes patented DuaLink dual frequency diversity system

• Internal and one remote receiver • Patent pending ModelMatch prevents flying

a model using the wrong model memory (feature does not work with module systems)

• Flight Log Compatible • SmartSafe failsafe system

F. Camera

We selected the DX201 DPS camera. It incorporates Pixim’s Digital Pixel System® technology which revolutionizes the way video cameras capture and process images. Unlike traditional cameras, where each pixel cannot adjust to highlights and lowlights in the same scene, Pixim’s patented Digital Pixel System technology empowers hundreds of thousands of pixels to act like constantly self-adjusting individual cameras. This all-digital system enables Pixim-Powered cameras to efficiently capture the whole picture, regardless of lighting condition or application – thus securing the highest resolution, natural color and clarity, while automatically eliminating image compromising visual noise (e.g., glare, reflections). The result is more than superb image quality; it is accurate, actionable information that gives users the strength of certainty.

G. Batteries

1) Main Power Supply We have two Rhino 4900mAh 4S1P 14.8v 20C

Lipoly Pack to power our motor and servos. Experimental results show that these batteries can exhibit a total flight time of approximately 40 minutes.

2) Electrical Peripherals Supply To power our Micropilot we use a standalone

4.8V battery from Hydrimax. With large capacities of up to 2000mAh and 4200mAh, the HydriMax Ultra rechargeable nickel-metal hydride (NiMH) packs deliver longer flight/run times than any batteries we have previously tested. We chose a 4.8V and a 6.0V flat and square receiver packs. The 6.0V pack powers the receiver and serves as a back-up to the Micropilot Autopilot.

H. Antennas

Our UAV has 2 ULTRA 2.4GHz High Gain Omni-Directional Antennas. ULTRA delivers high quality data to the router by the means of the ULTRA 2.4GHz High Gain Omni-Directional Antenna. The addition of this powerful device to our network increased wireless stability, and gave our network a noticeable boost. These antennas connect to the RP-SMA connection on a router and boosts Wireless N devices.

i. Features of the Antennas: • Stronger signal increases wireless coverage

into hard-to-reach areas • Improves throughput by reducing

retransmissions • Works with Wireless N device

I. Electrical Components and Weights

Components Weight

Motor Brushless Out runner (g) 414

ESC-Electronic Speed Control (g) 60

LiPo 4200 mAh (g) 578

Lumix Panasonic Camera (g) 154

Receiver battery (g) 5

Receiver (g) 17.58

Micropilot (g) 28

IV. ELECTRICAL SYSTEMS (GROUND)

A. RC Transmitter

Combining Spektrum industry-leading 2.4GHz DSM® technology with real-time telemetry the DX8 represents a breakthrough in 8-channel sport-level radio systems.

The telemetry module is expandable based on the module needs; the module is capable of supporting Quality of Signal (Antenna Fades, Frame losses, holds), Receiver Pack Voltage, RPM, Temperature and Flight Pack Voltage. We have added the safety of real-time telemetry and monitor vital aircraft stats right from their transmitter without any additional equipment. It will keep our engine operating in the optimum temperature range, keep an eye on battery voltage, and check out just how fast the aircraft is running all right from the large LCD readout of the DX8.


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Image: RC Transmitter

B. Video System

1) Antennae For video reception we selected a 2.4 GHz 8 dBi

LH Circular Polarized Patch Antenna - 12in N-Female Connector.

The HyperGain HG2409PCL series antennas are a compact Left Hand Polarized flat WiFi patch antenna providing 8 dBi gain with very broad coverage. The use of a circular polarized antenna on a fixed AP is advantageous due to the linear polarized remote links that are constantly moving. Circular polarized antennas have equal response to either horizontal or vertical polarized antennas. It is suitable for our UAV application since is for outdoor applications in the 2.4GHz ISM band, including IEEE 802.11b, 802.11g and 802.11n, Bluetooth® and for wireless hotspot applications.

a) Features:

• Compact size, 4.5" Square with 12 inch low-loss coax lead

• Durable UV-stable, UL flame rated • Low-loss solid brass element & DC Short

lightning protecting • Optional pigtails and mounting brackets

available • Optional mounting brackets available • Higher range than omnidirectional antennas • Sturdy and Rugged Case • Waterproof

b) Antennae Patterns:

Figure: Antenna Patterns

2) Receiver Our system uses an 8 channel, 2.4GHz Wireless

Audio/Video Receiver.

C. Horizonmp

HORIZONmp provides a visual interface to Micropilot autopilots. You can track the flight path using a moving map display, monitor the aircraft status and flight conditions, and control payloads.

HORIZONmp is also a computer interface to the autopilot that manages transmitting flight plans, and recording telemetry and sensor data.

Figure: Horizonmp Interface

The HORIZONmp ground control software is a user-friendly interface for communicating with your MicroPilot Autopilot. It can act as a setup tool to create and load flight programs, change feedback gains, and configure sensors and servos. Its main function, however, is to allow you to observe and interact with the UAV while it is in flight.

1) The Map The map has two functions. When one flies or

simulates a flight, it displays the route (waypoints) and the position of the aircraft. When one plans a


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flight, one will arrange the waypoints on the map so that the route the aircraft will take can be seen.

Figure: Map in Horizonmp

While in flight, HORIZONmp shows the aircraft, its trail, and the waypoints. HORIZONmp constantly re-centers the display on the aircraft as it moves over the route. As the aircraft moves towards the next waypoint HORIZONmp highlights the waypoint in green.

To add waypoints to the map, one simply has to right-click on the map to display the Append Waypoint Type pop-up menu. Or select and right-click on an existing waypoint to display the Selected Waypoint Options pop-up menu to move, edit, or insert waypoints.

2) The Instrument Panel

The instrument panel provides a lot of information in a very compact space. It displays current and target speed, heading, and altitude as well as throttle and battery status. These are all color coded for ease of understanding.

Figure: Instrument Panel

a) Airspeed Indicator

The airspeed indicator shows the speed of the aircraft relative to the air. The units of measurement, either knots or kilometers per hour, are shown near the top of the gauge. The field above the airspeed gauge displays the target airspeed for the current stage of the flight. The buttons on either side allow you to increase or decrease the target speed.

Figure: airspeed indicator

b) Attitude and Heading Indicator

HORIZONmp combines the attitude and heading indicators into one instrument. The attitude indicator is sometimes called an artificial horizon. It shows the attitude of the aircraft, represented by the green W shape, against a horizon represented by a blue “sky” and brown “ground.” Pitch is marked in 10 degree increments above and below the artificial horizon. Bank is shown on the arc at the top of the instrument, also in 10 degree increments.


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Figure: Attitude and Heading

c) The Altimeter

The altimeter shows the altitude above the initialization point. The units of measurement, either feet or meters, are shown near the top of the instrument. The large hand indicates 100s of the unit and the small hand, 1000s of the unit.

The field above the gauge displays the target altitude for the current stage of flight. The buttons on either side allow you to increase or decrease the target altitude. The autopilot will hold this altitude until it receives a command to change it.

D. Main Computer System The main system will make use of three sub-computer systems. These are composed of a MacBook Pro, a DELL INSPIRON, and an HP Pavilion.

V. M ISSION

A. Pre-Flight Checks

1) Physical Check The team will make sure that all components are

safely mounted on the aircraft. We will determine if there are any issues that may need attention before the aircraft is deemed suitable for flight. Test will be performed to ensure that the motor, esc, and receiver are in sync. Also, that all the components and batteries are safely placed in the empennage.

2) Systems Check Before we fly, we will prepare a flight plan that

defines the route that will be flown. We will check that Horizonmp: • Displays and configures maps • Uses waypoint commands • Adds and edits waypoints on the map • Adds a mission file to our waypoints

a) To Fly or NOT to Fly?

We will not fly if any of the following conditions exist. • The simulated flights that we performed failed in any way.

• Winds exceed the capabilities of the aircraft. They must be lower than 50% of the aircraft’s cruise speed. • The UAV and autopilot are not completely operational

b) Verifying Operation

A fter initializing the autopilot, we will perform the following pre-flight checks:

• Control surfaces are free and move in the correct direction. Rotate the aircraft about its pitch, roll, and yaw axis.

• Check that the elevator, ailerons, and rudder move to compensate for these movements.

• Main and servo battery voltages are OK. Check the battery voltage gauges on the instrument panel.

• • Airspeed indicator is working • • Press your finger firmly on the pitot tube

and check that the airspeed gauge shows an increase.

• All computer and test equipment is disconnected

• Engine runs smoothly at idle and full throttle • Control surfaces are in the neutral position in

UAV mode • Communication status indicators are green • RC range is adequate

B. Waypoints

A waypoint is a pair of coordinates on the map that define a point in the aircraft’s flight plan. The first coordinate in the pair defines longitude and the second, latitude. Waypoints on our autopilot can be either relative or absolute coordinates. Relative coordinates are the distance (in feet or meters, depending on our choice of measurement system) from the starting point on the map. Positive points are to the north and east. For example, a relative waypoint of −50, 30 is 50 meters (or feet) to the west of the starting point and 30 meters (or feet) to the north. We will use relative waypoints if we decide that we want the UAV to fly the same path regardless of the takeoff location.

1) Reaching waypoints HORIZONmp uses three different commands to

reach waypoints:


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a) flyto

The aircraft will fly to the specified waypoint maintaining current altitude and speed. This command does not correct for wind drift. If there is wind, the aircraft will point to the flyto waypoint but the flight path will be curved.

b) from to

The aircraft will fly to the next waypoint along the straight line. This command continually corrects for wind drift.

c) circuit

The aircraft will fly a circuit and attempt to land at the waypoint. A circuit waypoint must be the last waypoint in the file. We will use a circuit waypoint it you want to land in a location other than the takeoff location

C. Flight Simulation

We will simulate our waypoint files before using them in our actual UAV. Simulating a flight allows us to verify that our waypoints are correct, and running simulations is an excellent way to learn how the system will react to the use HORIZONmp.

By running a simulation one can see how the takeoff, landing, and holding patterns that are a part of the mission file operate. However, there are some things that one cannot simulate. • External sensors • External payloads • An onboard video camera • Low fuel or battery conditions • Ground elevation

D. Loading Waypoints

After transmitting waypoints to the autopilot and verifying autopilot operation with the preflight checks, we are ready to fly.

1) Starting a Flight: 1. We will transmit the waypoint file. 2. Connect to the autopilot and wait for the READY status indicator to turn green. 3. Perform the pre-flight checks. 4. In the Autopilot Control group, click Arm. Clicking Arm tells HORIZONmp that a launch is about to happen and to expect the transition from ground mode to flight mode. 5. Click Takeoff. HORIZONmp tells the autopilot to start the takeoff sequence. The engine will advance to full throttle.

2) Flying in RPV mode 1. In the Autopilot Control group, we only have to click UAV. The button changes to RPV and the RC Transmitter will now control the aircraft. We can also use the buttons on the airspeed indicator, heading indicator, and altimeter to change the target settings and control the UAV. 2. To change back to UAV mode, we can click RPV.

3) Editing Waypoints in Flight We must left click on a non-active waypoint that we want to move and drag it to its new position. As we move the waypoint, its coordinates appear in the Waypoints group in the HORIZONmp window. One can use this information to position the waypoint precisely. HORIZONmp and the autopilot are in constant communication with each other.


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HORIZONmp will transmit the new position the next time it polls the autopilot.

4) Redirecting the Craft in Flight 1. We select the waypoint to which we want the autopilot to fly. 2. We will right-click to display the Selected Waypoint Menu. 3. We will select Fly to select waypoint. The autopilot rapidly changes course and flies to the waypoint.

5) Uploading new Waypoint file in Flight 1. We will check that the HORIZONmp communication status indicators are green. 2. From the Flight Files list, we will select a waypoint file to send to the autopilot 3. We will click the Transmit waypoints button. HORIZONmp sends the waypoint file to the autopilot and displays the new waypoints in the map. When one sends a new waypoint file to the autopilot, HORIZONmp does not overwrite the holding patterns or mission type from the original waypoint file.

E. Operating Payloads

Although payloads can take many different forms on our UAV they always fall into two categories. They are either remotely operated devices carried by the aircraft or a set of instructions to control the aircraft. HORIZONmp has two kinds of remotely operated payload controls—button controls and slider controls. Button controls control the servos of our camera.

1) Video Payloads

When HORIZONmp’s video function is enabled, we can view and save video streams, and save video frames as bitmap images. When video is enabled, the Video window automatically appears on top of the map. HORIZONmp saves the video and image files in the video folder within the Horizon3.2 folder.

a) Types of Video or Image files.

1. Main video stream HORIZONmp records the main video as it receives it and uses the file name format video-yyyymmdd-hhmmss.asf. The date and time in the file name is the time that the video started. 2. Second video stream The second video stream is a portion of the main video which can be reviewed while the UAV is in flight. Its file name is video-snapshot- yyyymmdd-hhmmss.asf. HORIZONmp records it when you click the Start tool in the Video window. The date and time in the file name is the time that the video started. 3. Image snapshot An image snapshot is a saved video frame with the file name image-hh_mm_ss_ff.bmp. hh_mm_ss. The file name is derived from the time in the main video recording that the frame was saved and the frame number (ff) within that second.

F. Autonomous Takeoff and Landing

1) Takeoff There are a number of ways to perform an

autonomous takeoff. We chose the method best suited to our UAV. • Take-off using HORIZONmp or HyperTerminal In HORIZONmp we click the Arm button and then the Takeoff button. In HyperTerminal press the‘t’ key four times. In both cases the autopilot will advance the throttle to full for 4 seconds. If the autopilot detects the aircraft moving down the runway, it maintains full throttle and continues the takeoff process. If the autopilot does not detect movement, it reduces the throttle to idle. This method works well for traditional runway takeoffs.

2) Landing Our UAV is capable of starting a landing circuit

from the current position. The circuit command includes both the approach and the flare command. The circuit command has three optional parameters.

a) Circuit Landing Parameters

• Waypoint: To perform a circuit at a location other than the origin, we can enter either relative or absolute waypoints in the waypoint parameter.


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• Runway direction: To land the plane in a direction different from the take-off direction, we can enter a runway heading. Right hand circuits are the default; we can add a minus sign (-) to the runway heading to fly a left hand circuit. • Altitude offset: We can enter an altitude offset to when the landing location is not at the same level as the takeoff location. We do this by entering the difference between the locations in feet.

b) Method to Follow

We will start by making sure that all gains are stable at the speed at which the UAV will be flying the circuit. The cruise speed must be set to equal the circuit speed. [cruiseSpd]=[approachSpeed] When we become satisfied with the gains as acceptable, we will fly a circuit at a safe altitude to make sure that the parameters used by the circuit command are set properly. The easiest way to achieve this is to increase the circuit altitude so that the circuit is high enough that our MicroPilot Autopilot will fly the final approach at a safe altitude. We will increase the circuit altitude and decrease the length of the final leg of the circuit. At this point we will ensure that the gains are set so that the UAV flies along the center of the runway on the final leg of its approach.

G. Modem Communication

Because we are using a video link in the airplane, we can use the audio channel to send data from the MicroPilot autopilot to HORIZONmp. This configuration has two unidirectional links between HORIZONmp and the aircraft. The uplink operates using radio modems. We can use either spread spectrum modems like the ones used in the single link configuration or simple radio modems without error correction. The downlink operates over the audio channel of the video link.

Figure: Modem Link

1) Advantages • Uplink and downlink are on separate channels

Separate links mean that it is less likely that we will lose the uplink and downlink at the same time. By using separate channels we also made the configuration truly full duplex. • Higher power which translates to increased range • Better choice of frequencies. There are many other frequency bands available in addition to the 900MHz and 2.4GHz bands.

H. Image Recognition

We will accomplish our image recognition by using the MATLAB® AUVSI platform and integrating with an artificial neural network. We will use the video stream and send it to a video processing system for which we developed a stream processing architecture, in which video frames from a continuous stream are processed by sampling. MATLAB provides a Computer Vision System Toolbox™ which supports a stream processing architecture through System objects (for use in MATLAB®) and blocks (for use in Simulink®). We will implement our architecture to analyze video with methods such as edge detection, blob analysis, template matching, optical flow, and corner detection.

VI. REPORTING

A. Telemetry

HORIZONmp records two types of telemetry: standard telemetry and user defined telemetry. The user defined telemetry is only recorded if it is enabled on the MicroPilot Autopilot (See the TLM tab in the Editing VRS File dialog box). User defined telemetry allows us to specify which fields are transmitted each second. User defined telemetry is sent at a rate of 5 Hz. and is stored in the tlm.txt file in the HORIZONmp directory. Each column in the field corresponds to one user defined field. When GPS time is set as a user defined field, time is recorded as the number of tenths of a second that have passed since midnight Greenwich Mean Time on Saturday of that week. The MicroPilot Autopilot field GPS_TIME (field ID 1224), records GPS time in tenths of a second.


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B. Data-Log

Our MicroPilot Autopilot provides an extensive internal data-log that can be used to analyze flights after the fact. The autopilot starts recording data in the data log at the start of a flight (once GPS speed is greater than zero) and stops when the buffer is full. The MicroPilot Autopilot will also start recording a data log as soon as it initializes if the fake GPS lock has been enabled. We can force the data log to start recording as soon as the autopilot has initialized. Data is recorded at a rate of five samples each second. The data log is automatically cleared after the GPS locks and the sensors zero.

C. Trace Route

The trace route shows sensor level by location. The color of the trace indicates the sensor level. This display is especially useful for monitoring conditions over a route.

Image: Two passes During the course of the flight, HORIZONmp displays the route as a series of colored dots. The colors correspond to the sensor level at that point of the flight. The left side is a color code for the display. Blue indicates the lowest level and red the highest.

D. Strip Chart Display

The strip chart is a graph that shows each sensor, in a different color, against flight time on the X axis and the percentage of maximum value on the Y axis. Since it shows changes over time, it is useful for monitoring conditions at a particular time during the flight.

Image: Strip Chart Display The sensors are color coded and labeled on the right. The Y axis of the chart represents a percentage of the sensor level and the X axis is the time during the flight. When the flight is over, we can review the chart by right-clicking and dragging on the strip.

E. Contents of Report

The final report given to the Judges will contain the following information:

• Target shape, color, heading, GPS position, and alphanumeric character.

• Detailed explanation of autonomous acquisition.

• Link to video file that shows the system acquiring the target autonomously.

• Flight path, including a trace route and a strip display.

F. User Telemetry

The HORIZONmp telemetry function collects and saves sensor data from a flight for later analysis. HORIZONmp saves telemetry data as a space delimited text file—tlm.txt—in the logs sub-folder under the HORIZONmp program folder. It can easily be imported into spreadsheet and database applications. The user telemetry file name identifies the UAV and the time the file was saved. Its format is UAV-#-usertlmyyyymmdd-hhmmss.txt.

1) Importing to Excel To import telemetry into Microsoft Excel 1. On the Excel File menu, we will click Open. The Open dialog box will appear.


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2. In the Files of type list, we will click Text Files (*.prn; *.txt; *.csv). Excel will show text files in the file box. 3. Finally, double-click on the telemetry file we want to import and run the wizard.

VII. ACKNOWLEDGMENT

Ana Puente thanks Mr. and Mrs. Palencia for their lessons on flight and maintenance of our UAV project.

Viurniel Sanchez thanks Dr. Barreto for his recommendations on the software architecture used in this project.

Natalia Posada thanks Adrian Arbide, Jerry Miller, and Dr. Munroe for facilitating the Micropilot.

VIII. REFERENCES [1] Anderson, David, and Scott Eberhardt. UNDERSTANDING FLIGHT. SECOND EDITION. New York: Mc Graw Hill, 1976. Print. [2] Raymer, Daniel. "ENHANCING AIRCRAFT CONCEPTUAL DESIGN USING MULTIDISCIPLINARY OPTIMIZATION." Department of Aeronautics Kungliga Tekniska Högskolan Royal Institute of Technology. (2002): Print. [3] Raymer, Daniel. Aircraft Design: A Conceptual Approach. 3rd edition. American Institute of Aeronautics, 1999. Print. [4] Rossi, Marco. "DESIGN AND ANALYSIS OF A COMPOSITE FUSELAGE." Instituto Tecnológico de Aeronáutica. (2009): Print. [5] Jenkinson, Lloyd, and James Marchman. Aircraft Design Projects for engineering students. 1st edition. Oxford: Butterworth-Heinemann, 2003. Print. [6] Abzug, Malcolm. Airplane Stability and Control. 2nd Edition. New York,: Cambridge University Press,, 2002. Print. [7] AFSHAR,, SEPIDEH, and HOSSEIN SHAHI. "Design and Fabrication of a Delta Wing Micro Aerial Vehicle." INTERNATIONAL JOURNAL OF MECHANICS. 2007. Print. [8] Nelson, Robert, and Thomas Corke. "Modification of the Flow Structure over a UAV Wing for Roll Control." 45th Aerospace Sciences Meeting. (2007): Print. [9] Fielding, John. Introduction to aircraft design. Cambridge University Press, 1999. Print. [10] Cutler, John, and Jeremy Liber. Understanding aircraft structures. 4th Edition. Wiley-Blackwell, 2005. Print. [11] Taylor,J., Jane’s All the World Aircraft, Jane’s, London, England, UK, 1976 [12] 1995, Anderson Jr., John D., Computational Fluid Dynamics –The Basics with Applications: McGraw-Hill,Inc. New York, NY [11] McCormick, Barnes. “Aerodynamics, Aeronautics and Flight Mechanics”, Second Edition. 1995 John Wiley & Sons

[12] http://rcfoamfighters.com/blog/?p=446 [13] http://www.iai.co.il/18900-37204 en/BusinessAreas_UnmannedAirSystems_HeronFamily.aspx?btl=1 [14] Adams, Charlotte; Oct 7,2010 Article"avionics-intelligence-features-and-analysis" http://www.militaryaerospace.com [15] Lopez, Ramon:February 4, 2010; Aviation Today News - Article"Worldwide-UAV-Market-to-Top-$80-Billion" http://www.aviationtoday.com/regions/usa/ [16]http://www.centennialofflight.gov/essay/Theories_of_Flight/Stability_II/TH27G8.html [17] http://pma263webdev.bowheadsupport.com/studentcomp2010/default.html [18] http://www.webkorridor.hu/a-repulogep-szerkezete-Aircraft-Structure.htm [19] http://www.solidworks.com/sw/products/10194_ENU_HTML.htm [20] 2011 Ansis Technical Specifications. Overview of Technical Capabilities.Resource Library Document. www.ansys.com/staticassets [21] http://www.engineeredpartsinc.com/images/indentedHexLine.gif [22] http://www.eplastics.com/Plastic/Plastics_Library/TYPICAL-PHYSICAL-PROPERTIES-PLEXIGLASS [23] http://www.micropilot.com [24]http://www.hobbyking.com

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