AUVSI Student Competition 2014 Journal · PDF fileAUVSI Student Competition 2014 Journal Paper...

AUVSI Student Competition 2014

Journal Paper

Mechanical Engineering Team: Javier Lichtscheidl , Adam Nguyen, Eder Avila, Robert

Taylor, Travis Morgan, Adam Dominguez, Mark Nguyen, Jerome Moscoso, Urian

Borda, Rene Correa, Timothy Gulliver, Alex Bautista, and Chris St. Dennis.

Advisors: Dr. Nina Robson and Jake Bailey

Abstract

This paper describes the design, manufacturing, and testing approach taken by the Titan UAV

team in order to be able to compete in the annual Student Unmanned Aerial System (SUAS)

competition. The design approach for this year’s team was based on two main criteria:

Improvement in structural and stabilizing design from the plane designed the previous year, and

the requirements needed for the SUAS competition. The way this was completed was through a

vast range of material analysis, cost effective design, and creating a new plane design to fulfill

the requirements for the competition. Since the team is entirely made up of mechanical

engineers, the plane was not off-the-shelf, but rather designed and manufactured at CSU-

Fullerton. Most of the material on the plane was made out of carbon-fiber in order to create a

high strength-to-weight ratio that would improve on rigidity and structural stability. The payload

consists of all the electrical components that will enable the UAV to fly autonomously, follow

the corresponding waypoint navigation system, and gather imagery that will be streamed to

ground control. This includes the Raspberry Pi and Raspberry Pi camera, the Ardupilot board for

autonomous flight controls, and LiPo batteries needed to power the electronic components as

well as the 450 hp motor. This composition makes it crucial to provide stable flight, intelligence,

surveillance, and reconnaissance to ground control during flight missions.

CSU-Fullerton: TITAN UAV

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Table of Contents

1. Systems Engineering Approach……………………………………...……………………3

1.1 Mission requirements analysis

1.2 Design rationale

1.3 Expected performance

1.4 Programmatic risks and mitigation methods

2. UAS Design……...………………………………………………………………………..4

2.1 Design Description

2.1.1 Design of air vehicle

2.1.2 Method of autonomy

2.1.3 Data link

2.1.4 Payload

2.1.5 Ground Control Station

2.1.6 Data processing

2.1.7 Mission planning

2.2 Mission Tasks being attempted

3. Test evaluation results…………………………………………………………….……...17

3.1 Mission task performance

3.2 Payload system performance

3.3 Guidance system performance

3.4 Evaluation results supporting evidence of likely mission accomplishment

4. Safety considerations/approach………………………………………………..………...18

4.1 Specific safety criteria for both operations and design

4.2 Safety risks and mitigation methods

5. Conclusion……………………………………………………………………………….19


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1. Systems Engineering Approach

1.1 Mission requirements analysis

The goal of the SUS mission is to gather accurate ISR autonomously and in real time in

order to aid firefighters in identifying fire activity. Based on these goals and the SUAS

competition requirements the mission will entail the following requirements:

Perform autonomous flight

Identify Targets (Alpha-Numerical)

Locate Targets (GPS stamp)

Complete mission in required time (less than 40 minutes)

Weigh less than 55 lbs.

Be able to carry a payload

Fly waypoints with maximum 100 feet tolerance

Provide real time target information

1.2 Design Rationale

The air vehicle design was derived from the competition requirements listed in 1.1 and

also improvements from last year’s design. Last year’s design had some structural flaws

that added instability within the vehicle during flight. This year’s team chose to add

structural integrity, improve flight stability, and to have a maximum vehicle weight 30 ±

5 lbs. The autonomous flight board system was chosen to remain the same since it

worked last year, but to improve the image recognition system as well as the amplitude of

the signal being sent from the air vehicle to ground control. Besides these main design

needs and changes the team based the rest of the design on the mission requirements. The

air vehicle detailed designed for both structural and payload components will be

described in detail in section 2.1 of the report.

1.3 Expected Performance

Having a stall speed of about 37 mph, the motor will need to run at 76% of its power in

order to generate lift, which then will reduce the amount of power to about 40% at steady

state in order to cruise at its calculated cruise speed. The autonomous system used last

year is being used again and therefore autonomous performance is expected to work

efficiently and effectively. Structural rigidity and design of the air vehicle will have a

better stability than that of last year’s design as well as high strength-to-weight ratio in

order to carry the necessary payload.

1.4 Programmatic risks and mitigation methods

Section 4 correlates with the risks plausible and the mitigation methods involved. As

required in the SUAS competition rules, the Ardupilot board is capable of implementing

the air vehicle to react in the following cases: loss of signal of about 30 seconds, loss of

signal for 3 minutes and termination, and safety kill-switches used to prevent the air

vehicle from causing any injuries, damages, or any other hazard to any team member,

spectator, or any other person whom might be within close proximity or flight range of

the air vehicle.


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2. UAS Design

2.1 Design Description

The Titan UAV was designed to assimilate the structural design of Israel’s Heron UAV

(shown below) and consists of a twin-tail design that is attached to the wings via booms

and is carried via a pusher propeller.

Figure 1: Israel’s Heron UAV.

The air vehicle will be able to carry a payload and have a maximum weight of 30±5 lbs.

depending on necessary payload components. The structure of vehicle consists of three

materials: carbon fiber, expanded polypropylene (EPP) foam, and aluminum. The fuselage

consists of a three-ply inner and outer prepreg carbon fiber cloth of about 0.010 inches thick and

honeycomb layer in between (Nomex) of about 0.130 inches. This resulted in a fuselage

thickness of about 0.2 inches, but an increase in strength, stiffness, and overall structural

stability. The wing profile chosen was E-214 from Airfoil Tools and was selected for its high lift

to drag ratio. The profile specified was also chosen for having lift at a negative angle of attack in

order to minimize the chance of having any tail-strike. Both the rudders and elevator were

chosen to have the airfoil profile NACA-0012 from Airfoil Tools. The air profiles chosen were

for stability purposes and to be able to handle the backwash generated from the pusher propeller.

The EPP foam for both the wing and empennage were covered in carbon fiber cloth using a wet-

layup technique. For structural rigidity and support for the empennage, the wings have two

carbon fiber spars that are bonded on the inside of the wing at the chord length height. The

overall structural composition of the air vehicle is to be able to carry its payload with added

strength and minimizing the amount of weight added to the entire system at the same time. The

rest of the structural components will be addressed in more detail in section 2.1.1 of the report.

The payload consists of the following: the 7.4V LiPo batteries which will power the entire

electronic system, the gimbal for the camera system, the autonomous flight control board, servo

receivers, motor, electronic speed controller, Raspberry pi, Raspberry pi camera, Airmax Bullet,

Pitot tube, 3DR Telemetry, Receiver. These components were used in last year’s design and will

be used again due to the simplicity of the power setup and communication between the air

vehicle and ground control. The rest of the payload components will be described in section

2.1.1 of the report.


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2.1.1 Design Description of air vehicle:

When approaching an in-house designed airplane for a competition such as the one

described above, it’s obviously desirable to design towards ensuring mission success. It

was decided that the best way to ensure mission success was to incorporate redundancy

and safety into the design. What his specifically meant for the structure team was to

follow the design of a proven system and apply it to this particular application. The other

constraint that was a driving factor for many of the decisions made was that of cost. To

lower the cost, while at the same time design for reliability the team decided to explore

various layouts of airplanes and weigh their benefits, putting an emphasis on low stall

speed, high payload capacity, and ease of fabrication as well as modification. This year’s

design can be split into two portions: Structural and Payload designs. The structural

design included the following parts: Fuselage, Wings, Empennage, and Landing Gear.

Payload consisted of two branches: On-board communication and Flight Controls. To

assist with this task, a design process involving various morphological charts, pugh

charts, and basic literature surveys led us to make the basic decisions outlined below.

Table 1: Structure Decisions Table.

Topic Decision

Construction Type Twin boom tail pusher plane configuration

Wing Placement High Wing

Wing Shape Rectangular (constant chord)

Tail Style U-Tail

Motor Arrangement Single Motor, Aft Fuselage mounted

Landing Gear Style Tricycle

Fuselage

The Fuselage, as shown below in Figure

2, consists of three sections: the nose, the

middle, and aft sections of the fuselage.

These sections are connected at two

locations with bonded and bolted bulkheads.

The two joint locations are between the nose

and mid fuselage and the second is between

the back portion of the mid fuselage and aft

section. The design of these bulkheads is

mainly to be able to support shearing

stresses from both static and dynamic

loadings. The body of the fuselage is made

out of carbon fiber and an inner layer of

Nomex (honeycomb layer). This composition allows for a light weight body, while

maintaining strength to support the weight of the entire plane and its corresponding static

and dynamic force loadings. The shape chosen has relatively low effects on flight in terms

of lift to drag ratio, but each radius created at the corners decreases the amount of vortices

generated in flight. The main purpose of the fuselage is to support be able to carry a payload

of about 15 lbs. and support a gross weight of approximately 30 lbs.

Figure 2: Fuselage Top Assembly.


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Wings

The wing assembly, as shown in Figure 3, consists of a 7 ft. wing span and a chord length of

1 ft. The airfoil chosen was the E-214 foil for its high lift to drag ratio and low Reynolds

number applications. Since the plane will be locating targets, the flight speed will be around

55 mi/h and therefore it requires a low Reynolds number airfoil to be able to fly at a

laminar state and reduce form drag. Another reason why the E-214 foil was chosen was to

generate lift at a negative angle of attack.

Since the UAV will consist of a pusher

motor configuration and a twin tail via

boom configuration, the high lift at a

negative angle of attack will allow for the

plane to lift before either the tail or

propeller can strike the ground during

takeoff. The materials chosen for the wing

consisted of expanded polypropylene foam

for its impact energy absorption, chemical

resistance for the use of resin coating, and

its high strength to weight ratio. The wings

will have an outer layer consisting of

carbon fiber and a PT-2050 resin. The coated carbon fiber

will add strength to the wings and a smoother surface finish

to reduce parasitic drag from skin friction. Since the wings have to carry large force loads

during takeoff and surveillance flight, two carbon fiber spars were added to support the

wing from bending moments.

Empennage

The empennage, Figure 4, is responsible for keeping the aircraft directionally and longitudinally

stable throughout all aircraft weight loads, feasible flight speeds, altitudes, and allowable center

of gravity. All these scenarios can be summarized between the extreme conditions during

takeoff and landing. Our design consists of booms attached to both the vertical and horizontal

stabilizers; the booms are made of composite carbon fiber contributing strength and reduced

weight. The booms thread into the boom tail

interface that is machined from Aluminum 6061.

In order to be able to sustain the load from the

empennage, the wings will have two inner spars

running through the wing span centered with the

chord length of the airfoil. The Horizontal and

Vertical Stabilizers are the NACA 0012 airfoil

made of expanded polypropylene foam, which

allows the profile to generate an optimum lift,

drag and control. The airfoils also consist of the

carbon fiber-PT2050 layup for high strength to

weight ratio and reduced skin friction. Arriving at

this design was through a down selection process

of reverse engineering from the previous years

Figure 3: Wing Assembly.

Figure 4: Emepennage Top Assembly.


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Unmanned Aerial Vehicle in 2012-2013. Last year’s team mentioned how the aircraft was not

as stable as they preferred forcing the pilot to rely heavily on the controls, in order to improve

upon this issue a primary objective of ours is to increase the overall stability. We initially

narrowed the empennage design to two choices being an inverted V-tail or a U-tail. During

the preliminary design review we discovered the inverted V-tail had a novel look but it would

have been difficult and expensive to manufacture. The inverted V-tail also combined the

functions of the elevator and rudder into one control surface meaning reduced control of the

aircraft which is not what we desired. The U-tail was chosen for the feasibility of

manufacture, more stability control, and strength to support the backwash created from the

propeller onto the tail. The improvement of this UAV design is the critical benefit in increasing

the horizontal tail volume coefficient (HTVC) to have a value that upgraded the overall

stability. With the increase in the HTVC the aircraft isn’t as maneuverable as a fighter jet, but

more like a transport jet which is ideal for our flight regime being reconnaissance and

surveillance. By raising the HTVC, there is a larger area and that means a larger force

equipping greater leverage when restoring the overall longitudinal trim once the UAV

encounters any disturbances through its operating rigorous envelope.

Landing Gear

The final structural component consists of the main landing gear and the steering gear Figure 5.

The landing gear is made mostly from aluminum 6061 in order to be able to carry the plane’s

weight at static loadings and sustain impacts generated from landing. The tires are pneumatic

and made of rubber material to dampen the impact forces it receives. The main landing gear

consists of an aluminum bracketing that connects to the fuselage and extends at an angle of 45°.

This configuration will allow the main landing gear to distribute the impact force equally and to

reduce the bending moments generated from landing. The specific height chosen for the main

landing gear was designed to reduce the chances of having a tail or propeller strike during the

takeoff and landing phases of the plane. The main design for the front landing gear was to

have a steering mechanism that can taxi the air vehicle and also keep it straight during takeoff.

Figure 5: Steering and Main Gear Design.


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2.1.2 Method of Autonomy:

As expected of the APM 2.5, autonomous flight for the air vehicle is capable in conjunction

with software called Mission Planner. Mission planner is a ground control station used for the

dynamic control of an autonomous vehicle. Using the proper telemetry, Mission Planner can

monitor the vehicle’s status while

in operation and aid in the overall

stability of the air vehicle while in

flight through its given waypoint

coordinates. The flight controller

board used this year was also used

the previous year and

accomplished the given

autonomous flight mission

requirements. Mission Planner is

interfaced using windows, which

will be controlled from ground

control and will relay the

information back to the air vehicle

via the Airmax Bullet. As shown

below, the waypoint coordinates

can be created generated through

Mission Planner to communicate

to the APM 2.5 in order to be able to have autonomous flight.

2.1.3 Data Link:

Data relating to image recognition will be done based on the figure below:

Figure 7: On-board to Ground Control Communication.

Figure 6: Mission Planner interfaces with the APM 2.5 for

Autonomous Flight.


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2.1.4 Payload:

The payload system consists of two branches: Flight controls and on-board communication.

The Flight control system consists of the Ardupilot APM 2.5, which consists of an open

source development, 3-axis gyro, accelerometer, and barometer. The APM contains GPIO

ports for servos and sensors that will be used for the plane to be able to fly autonomously.

The software involved is Mission Planner. Mission planner interfaces google and will use the

coordinate system specified by the SUAS competition rules. With the Mission Planner, the

APM will be able to set up the flight control system to follow a waypoint system and be able

to configure the vehicle’s controls to fly within the discrepancy value of less than 100 feet.

Based on criteria needed to fulfill the competition rules, the APM 2.5 was chosen as the

primary source for flight controls (Table 2).

Table 2: Flight Controller Matrix.

The servos chosen were the A402 for cost, durability, volume, and compatibility with the APM

2.5. The motor chosen was a Scorpion motor that will run on two 25.9V in series and a single

7.4V LiPo battery in parallel to run a total of 33.3V. This single motor has the capability of

producing about 450 hp and will need the appropriate amount of voltage in order to reach takeoff

speed at about 76% throttle. The air vehicle control frequencies that the air vehicle will be

operating under are 2.4 GHzand 915 mHz.

The second branch of the payload system consists of the on-board communication system and

image recognition. The system will consists of a 7.4V LiPo battery that will power that sector of

the payload system, the Raspberry pi, Raspberry pi camera, the camera gymbal system, and the

Airmax Bullet. The Raspberry pi camera will feed a live stream to the Raspberry pi, which in

turn will be sent to ground control via the Airmax Bullet. More will be explained in section 2.1.5


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Figure 8: Camera Gimbal

System.

in relation to ground control and data link that was described in section 2.1.3.

The gimbal system designed below will enable for the camera

chosen to be rotate 360 degrees and also reaching tilt of about 90

degrees. The gimbal system was 3-D printed out of ABS and can be

seen on the right:

The air vehicle block diagram containing the entire payload can be seen below:

Figure 9: UAV Block Diagram Consisting of payload in corresponding locations on air vehicle.


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2.1.5 Ground Control:

The ground control station objectives are to process an autopilot system, image

processing, and navigation along with manual flight. For the autopilot system, the

Mission Planner software will be utilized to meet the competition rules. The Mission

Planner Software entails navigational controls where wave points can be set through GPS

coordinates that will allow the UAV to fly autonomously. The Mission Planner software

will also display the elevation, velocity of the UAV, and the GPS coordinates. The 3DR

telemetry, transmitting 915 Mhz, will be used for the navigation and autonomous flight.

One of the main objectives of the ground control station is to maintain a strong

communication link with the UAV. The Airmax Bullet M5 was chosen to be part of the

UAV because it’s capabilities of transferring data up to 100Mbps+ at longer ranges. The

Airmax Bullet will be connected to the Airgrid Antenna with an antenna gain of 27 dB.

The performances of these two components were chosen based on the analysis on the

component’s specifications. The analysis is composed of three equations below:

Table 3: Airmax Bullet signal analysis.

54 Mbps With Airmax Bullet

Distance (miles) FPSL (dBm) EIRP (dBm) SOM (dBm)

1 110.579 32 32.421

2 116.600 32 26.400

4 122.621 32 20.379

The least system of operating margin that a 5 GHz antenna can have is 10 dB before the

connection depreciates. From the figure shown above, at a distance of 4 miles the system of

operating margin is 20.4 dB. The ground control station will still have a strong link with the

UAV between 1 to 4 miles which meets the requirements of the UAV transmitting data to the

ground control station. The Airmax Bullet and Airgrid will be interfaced with the image

processing computer system. The image processing system will composed of a computer and

connects with the UAV via I.P. addresses. This will allow us to control the onboard system

and camera from the ground control station. The image processing computer will be

connected to a gigabit switch which routes the IP addresses connected to the navigation

Computer shown in the block diagram. The gigabit switch is used to access any data from the

navigation computer such as the GPS coordinates.

2.1.6 Data Processing:

Data transfer will be made using the Airmax Bullet and Receiver Antenna as shown

in Figures 10, 11, and 12 below:


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The data processed will be made using the Raspberry Pi in the following configuration

shown in Figure 11:

Figure 12: Data Processing Block Diagram.

When the target is recognized through the Raspberry Pi camera, the image will process the video

feed through the Raspberry Pi and transmit the live feed to the Receiver antenna, which in turn

will be visible by Ground Station. The goal is to be able to capture images of targets while also

live streaming video. This will require the Raspberry Pi to compress the images and send them to

ground Control. The other goal is to be able to attach and retract an infrared filter to the system.

This would enable the UAV to capture the I.R. targets during the mission, but it is still

undergoing construction and design planning.

Figure 11: Transmitter antenna. Figure 10: Receiver Antenna.


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2.1.7 Mission Planning:

Pre-Flight Assignments:

Before the flight it is very important that every member of the flight crew knows what the

mission requirements are and how to fully achieve all the mission goals. This briefing

must always be achieved at least 12 hours before the deployment assignment. During this

pre-flight assignment, the captain of the team announces the limits, the essential

objectives, the supplemental objectives and safety concerns depending on the

environment, time of day, region, and category of flight regime. The weather forecasts

need to be evaluated at this period to establish precipitation, temperature, and wind with

respect the restrictions of the systems. After all these checks have been secure each

member has to confirm they’re ready for the next deployment assignment.

Deployment Assignments:

Before approaching the flight demonstration, all the essential parts for certain subsystems

are put into separate containers for organization. Once the team arrives onto the field

each recognized group will open their respective container and start to assemble the

specific system they are in charge of. The containers are categorized into an aircraft

preparation consisting of payload, fuselage, wings, empennage, and landing gear. Also,

payload support hardware such as ground control and imaging stations will have their

own containers. Once the team has performed all appropriate tasks the head commander

must update all flight crew of all changes to the mission. Checks are then completed to

the operation criteria while adhering to the competition radio restrictions. In order to cut

down potential issues connecting and fastening the modules, it’s crucial to make certain

the standalone functionalities of each component. Then the final inspection is finished by

the head commander to bring to completion the operation criteria.

Takeoff Technique:

The takeoff stage of the mission is the most dangerous segment of the flight regime. All

the necessary flight precautions need to be acknowledged so that the aircraft can fulfill a

smooth operation. The safety pilots are trained for many hours on virtual simulations and

various aircrafts. The position on the airstrip will be dependent on which direction the

wind is facing. Once the plane is ready for takeoff we will have all members of the flight

crew that aren’t responsible for in flight objectives be advised to leave the area for safety

reasons. Once the members are evacuated the communications will be tested and the

engine will throttle to 100%. Once the takeoff speed is reached the aircraft will begin to

lift and will climb at a constant rate. At this point the aircraft will hold the desired course

in an autonomous mode but at any time throughout the flight the safety pilot may take

over control of the aircraft to prevent any catastrophic crashes.

Mission Arrangement:

Once takeoff has successfully been achieved the flight crew personnel that is in charge of

the ground station will keep a close eye on the autopilot overseeing that the speed and

altitude is calibrated correctly. Now the mission will begin with the predetermined routes

which will be inputted as the waypoints in Mission Planner within the command center.

After the waypoints have been initiated the chosen search pattern can be performed. At


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any time the mission can be modified to achieve all possible objectives. The next task is

to recognize all the targets using the digital camera within the payload. Once the targets

are identified they will be tracked using their position and characteristics confirmed using

the live video feed. In case of a failure to the autopilot the live video feed can be used to

navigate the aircraft.

Landing Technique:

After the mission is finished it is time to achieve a safe landing. The first step is for the

landing strip to be cleared for a safety. The autonomous landing is broken down into two

parts being an approach and compass lock. The approach of autonomous landing will

align the airplane for the precise altitude and the compass lock will orient the plane in the

correct position ensuring a safe approach to the landing strip. The final approach is

directed by an established gliding rate until the aircraft touches down to perform its slow

landing.

Post Flight Assignments:

Immediately after the plane lands the flight data is saved on the computer to interpret by

the right personnel. At the end of the mission each flight crew personnel disassemble the

subsystem components, place them in the correct container, and leave the flight zone.

Once the data is firmly analyzed we will look for potential failures during the flight and

make the appropriate changes in the software and hardware to prevent them from

happening again.

Mission Tasks Being Attempted:

Our flight control system is responsible for navigating through the waypoints without

direct manual inputs. In Addition, the flight control system is required to have a set of

safety aspects, such as manual override. In order to operate the mission sufficiently the

system also requires a ground station to contribute critical flight information to the

Autopilot Operator, as well as enable in-flight re-tasking. The autopilot system that was

chosen is the ArduPilot APM 2.5 Autopilot. It consists of the ArduPilot APM 2.5

Autopilot, a ground station, and the Mission Planner command center running on a

standard laptop. The Adrupilot APM 2.5 Autopilot and ground station each connect to a

GPS antenna which determines geographic position. The Ardupilot APM 2.5 Autopilot

employs gyroscopes to determine the aircraft orientation and is connected to a pitot tube

to calculate airspeeds. Through the Mission Planner command center, the Autopilot

operator can program flight plans, adjust control parameters, and ultimately command the

aircraft. The Mission Planner command center also provides the ability to perform in-

flight re-tasking. Furthermore, the Mission Planer command center supports a manual

control mode, which is toggled by a switch on the hand held transmitter, and allows the

safety pilot to take complete control of the airplane. During each of the flights, telemetry

data is automatically saved and can be interpreted at any time.


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2.2 Mission Tasks Being Attempted:

Section Task Probability of

Attempting

Primary 7.1 Autonomous Flight Task 100%

Primary 7.2 Search Area Task 100%

Secondary 7.5 Off-Axis Target Task 80%

Secondary 7.6 Emergent Target Task 80%

The full assembly model of UAV is shown below:

Due to complications within the manufacturing process, a full assembly of the actual air vehicle

has not being met yet, but will be ready before proof of flight. Sub-assembly Pictures will be

shown below in order to give the judges a visual of how the UAV is turning out after the design

process:

Figure 13: TITAN UAV Top Assembly.


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Figure 14: Fuselage after Prepreg Carbon Fiber Layup curing Process.

The Fuselage will be ready to assemble after the proper clearance holes have been made on the

plane. Below is a picture of the curing process for the carbon fiber booms, boom holders, and

middle fuselage-wing foam. The center part of the wing will go through a wet layup process in

order to be able to reduce skin friction and assemble to the top of the fuselage. The empennage is

complete and is being used as a gauge to where the boom holders will be allocated as shown

below:

Figure 15: Wing-Empennage Assembly and curing process of interfaces.


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3. Test Evaluation Results

3.1.1 Mission Task Performance:

Due to the long manufacturing process, the TITAN UAV has not been completed yet in order

to be able to be tested for all the mission task performances. Since the payload configuration

is the same as last year’s plane, the autonomous system has proved to work for the flight

mission. Flight tests have been made with test planes in which the same payload

configuration has been placed. The PixHawk flight controller has also been tested as a

backup source. The interface between Mission Planner and both flight controller boards have

been tested to communicate properly multiple times.

3.2 Payload Performance:

The components associated with the payload have been tested for connectivity, continuity,

and power required for system to be at steady state during operation. More tests will be

conducted once the full assembly of the Titan UAV is completed. As far as using the payload

components with test planes, it has been successful and working properly for the given

operations. Also, the configuration for this year’s design is the same as last year’s design and

has been successfully used to fly its mission. The camera has been also tested to provide

video feedback using the Airmax Bullet. The interface between the Raspberri pi camera to

the Raspberri pi and Airmax Bullet transmitter have been tested for communication

compatibility. The Airmax Bullet transmitter and receiver have been tested within a mile

range to test the signal strength. Although there were obstructions such as buildings, trees,

and other objects, the signal strength was about 25 dBm for the test duration. The Airmax

Bullet systems have been rated for 2 miles with a given signal strength of about 28 dBm with

a ±2 dBm tolerance under no disturbances. Since the competition site will not have

obstructions such as large structures or buildings, the operable distance should increase.

3.3 Guidance System Performance:

The Guidance System has been tested using the flight controller and interfacing software

Mission Planner using a test plane. The autonomous flight capabilities will enable for the

TITAN UAV to be able to complete the primary mission requirements. More flight tests will

be completed using the completed manufactured plane. Since it has worked for the test

planes and the previous year’s plane design, the system will be able to operate for the newly

constructed plane.

3.4 Evaluation Results:

Task Test Status

Autonomous Flight

Camera integration with Ground Control

Airmax Bullet Signal Strength

Motor Endurance Test To be completed

Flight Stability Test Under disturbances To be completed

Autonomous Recognition To be completed


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4. Safety Considerations Approach

4.1 Specific safety criteria for both operation and design:

Titan UAV is designed to meet the AUVSI competition regulations as well as system level

requirements. The aircraft was designed to not exceed 100 KIAS (115 mph) or the 55 lb

weight limit. Landing gear was designed to provide enough support for the aircraft when

taxing, but specifically the impact force when landing. The landing gear also plays a huge

role in ensuring that the propeller and empennage do not hit the ground when taking off or

landing. Titan UAV also has a fail-safe system in case of loss of signal or in need of manual

override through the flight controller board. In the manufacturing process the team operated

machine tools and worked with flammable and corrosive material. While working with

machine tools and corrosive materials the team wore personal protective equipment (PPE). A

safe-house was built to anticipate any battery failure in order to provide adequate safety for

the team member or any other personnel working in the affected perimeter.

4.2 Safety Risk and Mitigation methods:

Safety was a very important factor in the design process of Titan UAV. This year’s team has learned

from past experiences and designed the aircraft as a pusher propeller configuration. This

configuration was designed in order for the motor to be mounted in between the boom holders so that

if a member or anyone is near the aircraft they will not be in immediate danger from the propeller.

The system is composed of switches so that certain components of the aircraft will turn on when

specified as shown below. This will prevent the motor from turning on unexpectedly. The APM

system has a built in fail-safe mode in which it will activate if there is loss of signal for more than 30

seconds in which it will return to base. If there is signal loss for more than 3 minutes, the APM will

initiate death spiral to ground.

Figure 16: Kill-switch orientation for Battery configuration.


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5. Conclusion

The purpose of this journal paper was to show the rigorous design process and the

engineering approach to complete the autopilot, airframe, and payload systems. The

improvements made from last year’s team were the structural integrity from the carbon fiber

and honeycomb Nomex composition for the fuselage. This also gave a higher strength to

weight ratio for the air vehicle in order to maximize flight stability from bending moments

created from the tail and motor loads. The structural design improved from last year’s design,

but increased the amount of time devoted to the production of the vehicle and decreasing the

testing time. This in turn caused some delay within testing the autonomous system on the

complete system. The autonomous system and payload was tested on test planes and had

more hours used from last year’s team. Using the same flight controller board that

successfully worked for the previous year made it simpler to focus the design on the

structural aspect of the UAV. The goal of this year’s team is to solidify a structurally sound

UAV structure that can be used continuously in order for next year’s team to focus on the

autonomous target recognition and secondary tasks. This competition has given us the most

learning experience and practice of our engineering skills. Therefore, we are very thankful

that AUVSI has provided us with this opportunity.

Date post:	12-Feb-2018
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