3rd US-European Competition and Workshop on Micro Air Vehicles 7th European Micro Air Vehicle Conference and Flight Competition

MAV07 Istanbul Technical University MAV Team Murat BRONZ September 2007 Turkey

Abstract This paper represents the effort given to design of the Storm1 MAV in the presence of MAV07 mission requirements and integrate the whole hardware. Storm1 is a 500mm spanned tailless fixed wing, it has electric propulsion system capable of maintaining 20minutes of flight time, an onboard flight controller which is designed and produced by Paparazzi Project[1] Team Members. A CCD camera captures real time video stream which is transferred via 2.4GHz analog signal by a 100mW transmitter carried on the aircraft. Telemetry is acquired by 868MHz bidirectional digital modem, it has also a paintball release mechanism to fulfill the MAV07 mission requirements.

Mission Statement In order to enter the competition, the maximum distance between any two points belonging to fixed or moving parts of the vehicle should not exceed 500 mm. Also competition rules are restricting the maximum mass of the ready to fly MAV to 500grams.

For the mission the outdoor flight session has chosen and it will consist of flying a MAV over two separate 1.2X1.5- meter placards within a 1 kilometer radius and identify them. A third identified placard will have to be accurately located within a given area. A circular platform of 1.2-meter diameter will be placed at 1.5m from the ground to demonstrate vertical take-off and landing capabilities of rotorcraft MAVs. Finally, the MAV will have to fly through an urban canyon made of two balloon arches before landing in a predefined zone.

Score Sheet Assumption

Depending on the MAV07’s outdoor flight session scoring formula, three individual candidates are calculated for correspondence. From previous experience and competition results, a winner concept foresight has been built which is seen as red Candidate3, it is assumed to accomplish all the mission fully autonomously and have 250mm max dimension, it must be noted

that the VTOL task is zero for all the candidates because they are all fixed wing designs. The second white Candidate2 is small in dimensions again but doesn’t have autonomous ability so it should be noted how autonomy effects the score.

It is concluded that the score mostly depends on autonomy and then dimensions, so we set our priority to autonomy. Also we set our dimension to the maximum restricted limit which is 500mm for not to deal with severe stability and aerodynamic problems and also interference problems. Green Candidate 1 represents the desired mission task ability and possible score.[Table 1]

Design Strategy As it is stated in the previous section, autonomy and control of the aircraft is the most important thing so the autopilot selection is the key point. Paparazzi Autopilot is chosen for the control of the aircraft.

Table 1. Score Sheet and Candidate Airplanes MAV 07 Level of Autonomy Status

Tasks ak

Launch

Target1

Target2

Target3

SensorDrop

Arch cross

VTOL

Land

Lmax

R/C

1

0,1

0,2

0,2

0,1,2,3,4

0,2,3,4

0,1,2,4

0,2,4

0,2

500

Auto 1

2

Auto 2

6

ak

Launch

Target1

Target2

Target3

SensorDrop

Arch cross

VTOL

Land

Lmax

Score

Candidate 1

6

1

2

2

2

2

4

0

2

500

90

Candidate 2

1

0

2

2

4

4

4

0

0

300

43.90

Candidate 3

6

1

2

2

4

4

4

0

2

250

384.75

Autopilot Paparazzi is a well known and proven Open Source Autopilot. Open source soul of this project is the main reason that we choose Paparazzi and also the success of the teams that had used it for the previous competitions are very promising. Both software and hardware is being updating all the time and the flexibility is enormous so that there is nearly nothing that can not be done with the code. Paparazzi Team has integrated the processor board, GPS receiver and antenna, power supply in one board; that helps them to reduce the total weight and interference problems (Tiny). And to measure the attitude of the aircraft relatively cheap, off the shelf thermopiles are used which measure the far infrared radiation in 5-14µm range.

Figure 1. Tiny rev 1.13 Paparazzi Autopilot

Figure 2. Thermopile sensors

Telemetry For the bidirectional telemetry link, 868MHz Radiotronix Wi.232EUR-R digital modem is used because of the good references that previous Paparazzi users gave. For the RC uplink a well known Castle Creations Berg 4L 72MHz receiver is used.

energy consumption and choose a CCD camera from range video. For video downlink a 2.4GHz Analog Transmitter is used with an output power of 100mW.

Figure 5.CCD Camera and Transmitter Figure 3.Radiotronix 868MHz Modem

Propulsion

Figure 4.Berg 4L RC Receiver

A lot of off-the-shelf brushless RC electric motors were tested and finally HexTronik 1700Kv Brushless Outrunner motor is chosen and for the electronic speed control unit again from castle creations Phoenix10 is used, which is known with its robustness and working well above their rated current capacity.

Camera As we learned from the previous competitions the image quality is really important, and also camera system has the second priority in our design strategy according to our score sheet assumption. That’s why we compromised weight and

Figure 6.Hextronik 1700Kv Brushless Motor

Airframe As stated in the design strategy, after determining all the required component for our priorities (Autonomy, good picture quality) the airframe is drafted to enclose all the components and yet has enough surface area to fly . A highly reflexed airfoil is chosen for the root and a symmetrical airfoil is used at the tip thus giving an aerodynamic twist to the wing, this also enhanced the airplane’s handling qualities.

The preliminary and detailed design of the airframe is done with CATIA V5 CAD program, then the cross sections are taken and cut from plywood with laser cutter to form the male molds. This process has also reduced the huge amount of cost that is need for CNC machining. After the male molds have been finished, the fiberglass female molds are made.

Figure 7.CATIA Drawing

Figure 8. Plywood male mold parts in process

Kevlar, carbon, glass and expanded polypropylene foam (EPP) are used as construction material to make the airframe strong and robust to carry all the electronic equipments safely.

Figure 9.Carbon Kevlar Wing and Fuselage

Ground Control Station The ground control station consist of a standard notebook computer, a 868MHz RF modem connected via USB, a Hitec Flash5X RC Transmitter, 2.4GHz analog video receiver and a TFT screen for video. With an additional video adapter it is possible to implement the video stream to the Paparazzi Control Station which is also displaying various parameters of the aircraft like speed, attitude, altitude, GPS coordinates, battery condition and some estimations like wind speed and direction.

Mass Breakdown of the System

Table 2.Mass breakdown Airframe

95g

Processor board, GPS receiver and antenna

25g

Thermopile sensors

10g

Engine and ESC

39g

Battery

85g

RC receiver

4g

2.4GHz Video Transmitter

14g

Flight Servos

10g

Camera

25g

Propeller

3g

Paintball & Servo

8

Radiotronix Telemetry Transceiver

4g

Total

Figure 10.Paparazzi GCS Software

322g

Acknowledgments All the effort that has been given to this project totally refers to the Paparazzi Project[1]. Thanks to all of the Paparazzi team, Antoine Drouin, Pascal Brisset, Michel Gorraz, Jeremy Tyler, Martin Mueller and many others, it would be impossible to be able to maintain autonomous flight without their support.

References [1] A.Drouin, P.Brisset;”Paparazzi Project, http://www.nongnu.org/paparazzi”