Technical Description of the M.A.2C.'08 MAV M. Müller, A. Schröter, C. Lindenberg Team M.A.C., Hildesheim, Germany

A. Drouin

ENAC, Toulouse, France

1) Abstract: The M.A.2C.'08 micro air vehicle (MAV) system was developed by a collaboration of Ingenieurbüro M. Müller, Hildesheim, Germany and Ecole Nationale d’Aviation Civile (ENAC), Toulouse, France to compete in the 1st US-Asian Demonstration and Assessment of Micro Air and Unmanned Ground Vehicle Technology. It deploys three fully autonomous, electrically propelled fixed wing airplanes in parallel to meet the assessment’s reconnaissance, size, and distance objectives. Two are used to monitor the bank complex and the guard vehicle from different directions continuously. The third collects information on possible ingress routes and on the position of mines. Telemetry and video data from the MAVs are available online at a ground control station to provide information for mission planning, controlling the simulated mine sweeping UGV, and directing the rescue team. For the simulated UGV a remote control unit is provided which records the UGV’s GPS position, exchanges telemetry data with the ground control station, and displays direction and distance information for the UGV operators. Team M.A.C.

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2) Introduction a) Statement of the problem The 1st US-Asian Demonstration and Assessment of Micro Air and Unmanned Ground Vehicle Technology requires one or more teleoperated or fully autonomous MAVs with dimensions ≤30cm to provide online reconnaissance information for a simulated hostage rescue mission. This information includes the locations of the hostages, a moving guard vehicle, possible ingress routes, and anti personnel mines. The data is needed to plan the rescue mission, control a mine sweeping robot, and direct the rescue team. The MAVs shall operate in a 1km square. The ground control station is located outside this area. Most of the observed objects are beyond the line of sight relative to the ground stations position. Each MAV must contain a safety mechanism to ensure that the MAV returns under control of a safety pilot or terminates its flight whenever it leaves the given safety area or upon command of the judges. The mine sweeping robot may be simulated by a manned ground vehicle which is directed by telemetry data from the MAVs or from the ground control station. The detailed description of the competition is given in [OfficialRules]

b) Conceptual solution to solve the problem The M.A.2C. team uses a set of three fully autonomous MAVs to collect real time video data on all areas of the mission. The waypoints and search patterns of the MAVs can be altered in flight by a ground control station (GCS). Video data is transmitted to the GCS where it is stored and analysed online using video processing techniques like slow motion, single stepping, and fast forward/backward. The rescue team and the simulated mine sweeping UGV are equipped with a control unit which determines their current GPS positions, exchanges telemetry and guidance information with the GCS and displays direction and distance information. The MAVs can travel the distance between GCS and bank building in approximately 1.5 minutes. To gather information on static objects (terrain, obstacles, hostages, mines) only few flyovers are needed, since the video data can be replayed and analysed using slow motion. Constant observation is needed for the moving guard vehicle only. The mission can be completed within the given time frame (40 minutes). A mission looks like this: 1. MAV A+B observe the bank building to find the hostages and to monitor the guard vehicle 2. MAV C maps the area between ingress point and bank building 3. A path for the rescue team is planned based on hostage location, obstacle positions, and guard vehicle behaviour 4. MAV C searches the selected path for mines 5. The UGV is guided to the mines along the path to deactivate them Team M.A.C.

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6. MAV A+B observe the guard vehicle’s motions while the rescue team moves along the swept path 7. During the ingress the rescue team is told to hide, advance, or return depending on the guard vehicle’s behaviour to avoid detection. 8. The rescue team reaches the hostages.

b1) Figure of overall system architecture

*

*

Simulated EOD Robot

MAVs *

Telemetry

*

Telemetry + Video *

Telemetry + Radio

*

Remote Control (emergency only)

Rescue Team Ground Control Station

Safety Pilot

Fig. 1: Overall system architecture.

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c) Milestones 2005:

2006:

2007:

2008:

A fully autonomous, delta shaped, electrically propelled fixed wing MAV with a stabilized, two axis pan/tilt video camera system was built for the 1St USEuropean MAV (MAV’05) Assessment in Garmisch, Germany. It won the second prize overall and the special prize for autonomy. Detailed information is given in [MAV05, MAC05]. The onboard control unit was redesigned to improve its computing power and to reduce its size and weight. This design as well as the involved onboard and ground control software is publicly available via the Paparazzi open source project [Paparazzi]. A moulded MAV airframe was built from glass fiber reinforced plastic to improve the speed of the MAV. The video camera mounting was replaced by a one axis system to save weight and room. A sensor deployment mechanism including the necessary on-board software was added. This design won third place in the MAV’06 contest in Florida, USA. Details are given in [MAV06, MAC06]. A new MAV airframe was built from expanded polypropylene (EPP) to improve ruggedness and to reduce building effort. This airframe is commercially available. An indoor MAV based on a coaxial helicopter design was built. The MAVs won fourth place overall and a special award from the jury in the MAV’07 contest in Toulouse, France. Details are contained in [MAV07, MAC07]. A MAV for meteorologic research was built for the University of Bergen, Norway. With this we took part in a research expedition to the inland glacier in Iceland where it collected research data on atmospheric phenomena in harsh conditions and in altitudes up to 12.000ft [Iceland]. In collaboration with other members of the Paparazzi team [PaparazziTeam] an internet based system for controlling several MAVs in parallel from a remote control station was set up and demonstrated successfully during the 24C3 conference in Berlin, Germany. The MAVs flew in Toulouse, France and Hildesheim, Germany. The control station was located in Berlin, Germany displaying live video [24C3]. We took part in a research expedition to the border of the polar ice north of Spitzbergen, Norway where our MAV flew from the Norwegian ice breaker KV Svalbard to gather meteorological research data. [Svalbard08]. Three new fixed wing MAVs with a special focus on small size, low weight and ruggedness were built for the 1St US-Asian Demonstration and Assessment of MAV and UGV Technology. In addition guidance units for the ground based parts of this contest were built. Further development in 2008 will focus on fixed wing MAVs for meteorological research and helicopter based MAVs.

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3) Air Vehicle a) Propulsion and Lift System Propulsion The design goals for the propulsion system were - speed 15-20m/s - flight duration 20minutes with a single battery replacement - low weight - low vibration level - small size The propulsion system consists of an electronically commuted, brushless electric motor (Robbe 1820/16) driving a 125x110mm sized propeller mounted at the nose of the fuselage. Energy is stored in three lithium polymer cells with 850mAh capacity. Airframe The design goals for the airframe were - The MAV including propeller, sensors and control surfaces has to fit into a sphere with 30cm diameter. - Uncritical flight behaviour - Sufficient payload capacity (cp. Table 1) A delta shaped design was chosen to fit the maximum possible wing area into the given size limitations, i.e. to keep the wing load as low as possible. Theoretically a round wing would yield the maximum wing area under these conditions. However, this would require a very unpractical mass distribution inside the MAV including ballast to get the center of weight into a suitable position. Therefore the leading edge of the wing shape deviates from a round disc. The fully moulded airframe is constructed from glass and Kevlar® fiber reinforced plastic (GRP). Fig. 2 and 3 show the fuselage mold and the wing mold respectively. For the wing design a flat board profile using two thin layers of Kevlar® fiber with a Herex® spacer layer in between was chosen, since this results in minimum weight. The fuselage is made from two layers of 28 g/cm2 glass fiber fabric and a layer of Kevlar®.

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Fig. 2: Mold for the upper fuselage with a sample fuselage.

Fig. 3: Mold for the wing.

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Weights and dimensions The aircrafts wingspan is 28cm. It fits into a sphere of 30cm diameter including propeller and rudder. Considerable effort went into the weight reduction of the electronics components. The autopilot processor, the GPS receiver, its antenna and the power supply were integrated into one single board to minimize weight. module

weight

airframe

65g

engine w/ controller

24g

Propeller including prop saver

4g

Battery

60g

infrared sensor

10g

processor board, GPS receiver, antenna, power supply

19g

flight servos

10g

868MHz telemetry transceiver

6g

35MHz receiver

8g

2,4GHz video transmitter

8g

camera unit

6g

total

220g

Tab. 1: Component weights

b) Guidance, Navigation, and Control The M.A.2C.'08 MAVs contain an onboard flight control system (autopilot) which allows fully autonomous flight in daylight conditions with visibilities similar to visible flight rules (VFR) conditions. The autopilot controls the speed, altitude, angle of attack and roll angle of the MAV to execute the steps of a given flight plan. The flight plan is stored onboard, but can be altered in flight by the ground control station. Typical flight plan elements are among others “takeoff”, “fly to a requested location and circle it with given altitude and height”, “fly a search pattern in a given area”, or “return to base”. For security reasons the autopilot can be overridden at any time by a human safety pilot. Team M.A.C.

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As an additional precaution the MAV will return to base or shut down its engine whenever it leaves a given safety area or when connection to the ground station is lost.

b1) Stability Augmentation System - On Board Flight Control We designed the autopilot electronics together with members of the Paparazzi project. An ARM7TDMI 32bit 60MHz processor made by NXP is used for on board flight control (cp. Fig. 4). A standard RC receiver is used as a security uplink. The autonomous operation of the processor can be overridden by manual control at any time. There is a fly-by-wire process used for evaluating the RC receiver signal and to determine auto or manual operation. In manual mode the standard RC servo signals are passed through to the servos. In auto mode the signals are generated on board by the autopilot process. It uses the attitude information from the IR sensors (cp. section 4)a1) Guidance, Navigation, and Control Sensors) to set the taileron positions through PI control loops. The desired turn rate is calculated from the GPS position information and the given waypoints. The main control loop operates at 60Hz while the GPS data is updated at 4Hz. The processor load is less than 5% for the flight stabilization and waypoint calculation. The proportional and integrative values of the PI regulators were manually tuned in various test flights. The processor, GPS receiver, antenna and a switching power supply were integrated into one single board to optimize weight, size, electromagnetic interference and mechanical stability.

Fig. 4: Processor board with GPS and power supply

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b2) Navigation The on board flight controller supports three modes of operation: a) manual: In this mode the MAV is remote controlled by the safety pilot using a standard off the shelf remote control which is usually used for flying model airplanes. This mode is used for testing purposes and as a safety precaution. b) auto1: In this mode the safety pilot has control of the altitude, direction, and engine power of the MAV. The on board controller stabilizes the MAV’s roll angle. This mode was introduced for MAVs with little aerodynamic roll stability. It gives almost the same amount of manual control as manual mode, but reduces the strain on the safety pilot considerably. c) auto2: In this mode the on board flight controller has full control of the MAV. It controls altitude, course, roll angel, angle of attack, and engine setting fully autonomously to execute a given flight plan. Whenever the ground operator modifies the flight plan, it is immediately transmitted to the on board controller, and the MAV changes its objectives accordingly in flight. E.g. the ground operator can assign new waypoint coordinates using an aerial photograph of the relevant area. Section 5 Mission Operations contains details on the ground control station software and its man machine interface.

b3) Figure of control system architecture

IR sensor board attitude sensors

analog

GPS receiver

backup battery

UART

flight control board GPS antenna

On Board Flight Controller ARM7TDMI 35 MHz RC receiver

Central power supply

868 MHz telemetry transmitter

video camera

analog

2.4 GHz video transmitter

flight battery left taileron servo

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right taileron servo

brushless motor controller

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c) Flight Termination System The following flight termination systems are included for safety reasons: 1) The safety pilot can overrule the on board controller and the ground control station at any time by switching the MAV into manual mode. In this mode he can either fly the MAV manually or terminate the flight by shutting down the motor and entering a spin. This will bring down the MAV within less than 40m of its current position with little kinetic energy. 2) For each flight a safety area is defined. As soon as the MAV leaves the safety area – e.g. due to very strong winds -, the onboard controller terminates the current mission and either shuts down the motor or guides the MAV to a save home position. The abort behavior will be selected prior to the first flight according to the judges’ requests. 3) As soon as the telemetry (868MHz) or remote control (35MHz) connections to the MAV are interrupted, the MAV aborts the flight as described in section 2) Additional Security provisions The on board software is divided into two processes to minimizes risks due to faulty software. The fly-by-wire process evaluates the incoming RC signals and generates the servo PPM signals only. Its code is small, simple, very well tested and rarely modified. The larger and more complex software for sensor data evaluation is running in the separate autopilot process. In this way it is always possible to return to manual control even if unforeseen software problems occur in the autopilot process. Prior to each flight a software-in-the-loop-test can be executed in the ground station software environment to simulate the mission and to detect errors without putting people, property or the airplane risk.

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4) Payloads a) Sensor Suite The M.A.2C.'08 is equipped with sensors for position and attitude measurement and for video observation. All sensor data is forwarded to the ground control station via telemetry or video transmission. In parallel the position and attitude information is processed by the on board control system to calculate proper control surface and engine settings.

a1) Guidance, Navigation, and Control Sensors Six PerkinElmer TPS 334 infrared thermopiles are used for attitude detection (cp Fig. 5). The thermopile sensors measure far infrared radiation in the 5-14µm range. Due to the temperature difference between sky and earth the horizon can be detected by a pair of back-to-back mounted thermopiles. Two pairs of sensors are used to determine the pitch and roll angles of the airplane. The third pair is used to constantly measure the maximum infrared radiation difference between nadir and zenith for in flight calibration of the other sensors. This method works nicely on sunny and cloudy days and even in slight rain. Thin Polyethylene films can be used to protect the sensors from moisture as these are transmissive for infrared radiation. The horizon detection has its limitations on very cold days and in foggy conditions – similar to flight under visual flight rules (VFR). A detailed description can be found in Taylor et al [Taylor_etal]. The thermopile sensors are integrated into the aircraft's fuselage for reduced drag and vibration sensitivity as well as improved mechanical protection.

Fig. 5: Infrared sensors for attitude detection

An u-blox LEA-4P GPS receiver yields the 3D position and direction information. The signal is received through a circularly polarized ceramic patch antenna. Receiver and antenna are both located on the processor board and are mounted inside the aircraft. The patch is designed for a reception at 1580MHz in vacuum and is tuned to the GPS L1 frequency at 1575,42MHz by the GRP cover. Team M.A.C.

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a2) Mission Sensors The mission sensor for the assessment in Agra is a fixed focus color video camera (cp. Fig. 6). It is mounted inside the fuselage to protect it from mechanical stress and to reduce drag.

Fig. 6: Video camera mounted next to the attitude sensor.

While using single axis and double axis stabilized camera mountings in previous competitions we decided to use a rigidly mounted camera for this mission to optimize weight, size, drag, and ruggedness. To make the system as useful as a stabilized camera all video data is stored at the ground control station and is analyzed online using video processing techniques like replay, slow motion, single frame, fast forward/backward.

a21) Target ID/Loc of mines, terrorists and hostages The target and the locations of mines, terrorists, and hostages are determined visually by using video cameras mounted in the MAVs. Depending on the specific observation task different camera mounting angles are used. To map the access routes, find the mines, and monitor the guard vehicle the cameras will point straight down. To find the hostages inside the bank building the camera will look in flight direction with a 35o tilt angle.

a22) Acoustic Techniques not used

a23) Chemical/Olfactory not used

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b) MAV/UGV Communications MAVs and simulated UGV will communicate with the ground control station only. MAV-to-MAV or MAV-to-UGV communication is not used. For video downlink a 2.4GHz transmitter is used. The video pictures are transmitted as an analog frequency modulated NTSC signal (cp. Fig. 7). A digital 868MHz transceiver is used to establish a bidirectional telemetry link (cp. Fig. 8). A number of data messages can be chosen, e.g. attitude, position, waypoints, mission status, voltages or debug information. Commands can be given during flight, e.g. change of waypoint positions or flight plan flow.

Fig. 7: 2.4GHz video transmitter and antenna

Fig. 8: 868MHz telemetry transceiver, antenna

For the simulated UGV a controller similar to the MAV on board controller is used to handle GPS position determination and telemetry communication with the GCS. A display is added to provide distance and direction information for the UGV operator.

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c) GCS to MAV/UGV Communications The ground control station sends telemetry data to the MAVs and to the simulated UGV using the data linked described in the previous section. For the MAVs a separate 35MHz radio control is used to overrule the onboard controller in emergency situations and allow manual control by the safety pilot.

d) Power Management System In flight all onboard systems are powered from a single lithium polymer battery (3 cells, 850mAh). The battery voltage is transmitted to the ground station several times per second. The ground station displays and monitors the battery voltage and displays an optical alarm as soon as the voltage drops below a predefined threshold. In this case the MAV has to abort its mission immediately and has to return to base for a battery replacement. In normal conditions the MAV can fly on one battery for ~20minutes. In strong winds and at low temperatures the duration is reduced due to increased power consumption or reduced battery capacity respectively. Several power regulator circuits are available to provide the various voltages needed for the controller board, the video/telemetry transmitters, and the camera from a single main battery. Filters are used to shield the electronics from the electrical noise generated by the motor. The power regulation and filtering circuitry is smaller, lighter, and more reliable than separate batteries. To avoid the lengthy GPS start-up times after a cold start (i.e. after initial connection to a battery) a standby battery is used for the GPS receiver besides the main battery.

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5) Mission Operations a) Flight Preparations During a mission the following types of ground operator tasks are taking place: Role ground control station operator

safety pilot

video observer

Tasks - monitor the telemetry data from MAVs, UGV, and rescue team - adapt MAV flight plans e.g. by moving waypoints - adapt UGV and rescue team destinations by moving waypoints - launch and land MAVs - observe the MAVs in flight - fly the MAVs in manual mode in case of emergencies - abort flights in case of emergency - Evaluate the video data (find hostages and mines, observe guard vehicle etc.) - Plan the ingress route - Give radio advice to the rescue team - Suggest waypoints for MAVs, UGV, and rescue team and forward them to the GCS operator

The workload and complexity of each task requires a thorough training of each team member prior to the assessment.

a1) Checklist(s) Before each flight a pre-flight checklist is used to make sure that all necessary preparations have been done and that the MAV is air worthy and the ground control station is fully operational.

b) Man/Machine Interface Ground control station The ground control station (GCS) consists of a laptop computer and a 868MHz modem that is connected via USB. The telemetry data is decoded in the laptop computer and various aircraft parameters can be displayed. The aircraft position is shown using Google Maps (cp. Fig. 9). Flight plans are generated using a script language. Waypoints can be set and changed through the graphical interface of the GCS system. The flight plan is downloaded to the aircraft using USB. In flight the flight plan flow and waypoints as well as control parameters can be adjusted.

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Fig. 9: Paparazzi ground control station software utilizing Google maps

A single ground control station is used to control all MAVs simultaneously. Video operator’s workstation The video operator’s workstation consists of a laptop computer which is connected via USB to a 2.4GHz video receiver including a video digitizer. The video stream is stored on hard disk and displayed using a video processing program. In this way the video operator can use functions like slow motion, single frame, reverse, or fast forward. For each MAV a separate workstation is used.

c) Route Planning/Commando control The planning of the ingress route is based on the video reconnaissance data. Obstacles, hiding points, the location of the hostages, the length of the route, and the behavior of the guard vehicle is taken in to account. All locations which are important for the rescue team, e.g. obstacles, hiding points, mines, and the teams position, are marked by waypoints on the GCS screen. The rescue team and the EOD robot are equipped with a telemetry and display unit including a GPS receiver. This unit sends its current position to the GCS and receives and displays heading and distance information from the GCS. The display is similar to an outdoor GPS, which is used for cross country hiking (e.g. Garmin etrex) (cp. Fig. 10).

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Fig. 10: Heading and distance display for the rescue team and the simulated EOD robot

The rescue team and the EOD robot are guided by selecting their next destination point on the GCS and sending the matching heading and distance information to their display. Additional instructions like e.g. “stop”, “hide”, “run”, “slow”, “wait” are given via radio. This approach avoids any confusion on the rescue team’s/robot’s current position and the direction in which it should move. While the rescue team is progressing, the guard vehicle is monitored by an MAV. The current position and the line of sight of the guards is taken into account while guiding the rescue team.

6) Risk Reduction a) Vehicle Status The MAV`s onboard control unit sends telemetry data on the MAV’s • position, • altitude, • attitude, • heading, • battery status, • motor setting, • current flight plan task, • desired height, • desired course, • GPS status, • autonomy mode Team M.A.C.

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several times per second. Additional values can be added depending on the payload. These values are shown on the GCS display in an ergonomically optimised format. Figure 9 shows an example. Position, heading, and desired course are plotted on an aerial photograph or an electronic map of the terrain. Attitude, height, and velocity are shown on the primary flight display which imitates the systems used in commercial and military airplanes. Additional values are displayed in numerical format. These values are highlighted in red as soon as they leave a predefined range to attract the GCS operator’s attention. In addition critical information is emphasised using voice synthesis. The changes of values over time can be displayed by the GCS using plots like the curves in figures 11-16. Prior to each flight the mechanical and electrical status of the MAVs are checked according to the pre-flight checklist.

a1) Shock/Vibration Isolation By using an electric motor, balanced propellers, and a very rigid wing the vibration level of the MAV was reduced to a level at which no dedicated vibration isolation is necessary. For mechanical protection during landings all electrical and electromechanical components are mounted directly to the wing inside the glass fibre fuselage. In this way elastic deformations of the fuselage during landings do not loosen or harm the internal components. The propeller is mounted using an elastic prop saver to prevent broken propellers during landings.

a2) EMI/RFI Solutions In a densely packed environment EMI is a serious issue. A small UAV contains a lot of electronic components very close to each other. The video transmitter and the telemetry transceiver radiate strong electromagnetic fields. Other parts also radiate during their operation: the switching supply that works with high current loads at about 100kHz operating frequencies and the main processor which has internal operating frequencies of up to 180MHz. The problems arising from the power supply and the main processor have been eliminated by putting them very close together in one place and shield them through a special four layer board design. The innermost layers are dedicated to the electrical ground and to the power supply voltage respectively. These two layers form a capacitor and short circuit any radiation generated anywhere on the board. Through this design the electromagnetic interference is minimized. Other methods being used are filtering capacitors at all power supply pins of the processor, filtering coils at the input of the GPS receiver and a decoupled ground plane for the GPS antenna. The GPS antenna and the rest of the board have only one single point in which the ground planes join. This removes the possibility of current loops on the board. Team M.A.C.

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Even during operation with high current loads on the power supply and with full processing power of the micro controller the GPS receiver is able to acquire a position very fast and shows better signal to noise ratios than a similar commercial reference design containing the same GPS receiver.

b) Safety Section 3b) Flight Termination System describes the technical safety precautions during the flight. Organisational safety measures include • a thorough training of all team members • clearly assigned and well defined tasks for all team members during a mission • communication between all team members during the flight • pre-flight checks according to a check list • replacement or repair of components as soon as any faults are observed • ground testing of all components • in-the-loop testing of components and software • testing of onboard software using a simulation environment • automatic regression tests of software components • version control of all software files

c) Modelling and Simulation The onboard software can be executed on the ARM7 onboard controller as well as in a PC simulation environment. The test environment simulates complete test flights including the communication with the GCS. Figure 9 shows a simulated test flight. The simulation environment reads the desired actor values (e.g. taileron positions, engine setting) from the onboard software under test, calculates the resulting flight behaviour of the MAV, and feeds matching sensor data back to the onboard software. During a simulated flight the onboard software under test communicates with the GCS so that the simulated flight can be displayed and command can be given in the same way as during a real flight. In this way software modifications und new functions can be tested on the PC without risking any damage. New MAV airframes are tested and optimized using manually controlled prototypes before the autonomous guidance system is used for the first time.

d) Testing Software is tested using regression tests and a simulation and test environment for the on board software as described in the previous sections. Hardware is tested on the bench (e.g. correctness of sensor data, influence of Team M.A.C.

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electromagnetic noise, influence of vibrations, mechanical stability of the airframe), during test drives in a car (e.g. correctness of GPS location and altitude, correct direction and velocity data, correct behavior of tailerons whenever the MAV is tilted or rolled) , and finally in the air. Test flight data During test flights telemetry data is recorded for offline analysis. The flight parameters recorded during a test flight are shown in Fig. 11-16. The aircraft covers a distance of approx. 150m three times from west to east and back again (cp. Fig. 11). The flight control system is configured to keep the aircrafts altitude constant using throttle and elevator. Passes from west to east are a little bit faster than vice versa, since the wind was coming from south west (cp. duration of upwind and downwind legs in Fig. 11 and speed in upwind and downwind legs in Fig. 15). The MAV's average ground speed is ~12m/s in upwind legs and turns and ~16m/s in downwind legs while it accelerates to 24m/s in downwind turns (cp. Fig 15). Bank angles during turns are approx. 15° (cp. Fig. 13). At the downwind turn point turns take approx. 10s, while the upwind turns are considerably shorter (cp. Fig 13).

Fig. 11: Position east-west direction

Fig. 12: Course

Fig. 13: Roll angle

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Fig. 14: Pitch angle

Fig. 15: Speed over ground

Fig. 16: Altitude

7) Ground Vehicle The simulated UGV uses a telemetry and display unit identical to the one used by the rescue team (cp. Section 5c Commando control). This transmits the UGV’s position to the GCS and receives direction and distance information in return. For short range navigation and mine detection a video camera and a video transmitter is mounted to the UGV. The video signals are evaluated in the base station by a video operator. In the vicinity of mines he directs the UGV by radioed commands.

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8) Conclusion Based on our experiences in building and flying autonomous fixed-wing MAVs and participating successfully in international MAV contests since 2004 we designed and built a system based on three MAVs, which is tailored for the aerial tasks of the 1st USAsian Demonstration and Assessment of Micro Air and Unmanned Ground Vehicle Technology. Parts of the onboard electronics were adapted and extended to guide a rescue team and a simulated UGV. For us the special challenges of this assessment are the extreme size limitations for the MAVs and for some of the observed objects as well as the complex overall mission involving simultaneous guidance of MAV, UGV, and a rescue team.

9) References [OfficialRules] [MAV05] [MAC05] [MAV06] [MAC06] [Paparazzi] [MAV07] [MAC07] [24C3] [Iceland] [Svalbard08] [Taylor_etal]

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http://www.nal.res.in/mav08/ http://aero.land.free.fr/aeromav/aero-mav-garmisch-de.htm http://pfump.org/pdf/glotzer_garmisch.pdf http://www.us-euro-mav.com/ http://pfump.org/pdf/mac06_florida.pdf http://paparazzi.enac.fr/ http://www.mav07.org/ http://pfump.org/pdf/mac_07_toulouse.pdf http://events.ccc.de/congress/2007/Fahrplan/events/2225.en.html http://www.flohof.uib.no/ http://en.wikipedia.org/wiki/KV_Svalbard B. Taylor, C. Bil, S. Watkins, G. Egan: “Horizon Sensing Attitude Stabilization: A VMC Autopilot”; chapter 6 “Horizon sensing” http://www.eganfamily.id.au/archive30nov2007/monash/research/papers/ TaylorBristol2003.pdf

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10 List of Abbreviations EOD EPP GCS GPS GRP IR LOS MAV NLOS PI PID RC UAV UGV VFR

explosive ordnance removal expanded prolypropylene ground control station global positioning system glass fiber reinforced plastic infra red line of sight micro air vehicle not in line of sight proportional integral proportional integral differential radio control unmanned air vehicle unmanned ground vehicle visible flight rules

11 Acknowledgements This work is part of the Paparazzi project [Paparazzi]. It would have been impossible to achieve autonomous flight without the generous open source idea and the fabulous cooperation of all Paparazzi members.

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