**2.1.3 Processor and control system**

The flight computer installed in avionics box is a typical industrial embedded computer system, so-called PC-104 in the whole system is kept as compact and light-weight as possible. The PC-104 has the ISA or PCI bus which features a 108.2cm 115.06cm footprint circuit board. Our flight computer system consists of a main CPU board and some other peripheral boards such as DC-DC power supply board, 8-channel serial communication device and PWM generation board. The main CPU board has a Celeron processor at 400MHz with 256MB SDRAM, fully compatible with the real-time operation system such as QNX. Hard drive or other equivalent mass-storage device for booting and running an operation system and storing useful sensor data is needed to the flight computer.

Application of Wavelets Transform in Rotorcraft UAV's Integrated Navigation System 617

The full duplex wireless-LAN equipments are installed in the ground station and the airborne system to exchange data between them including receiving commands from the ground system and reporting the operating status or possible damages to the ground

ServoHeli-40 RUAV platform is a flexible platform. It can carry 15Kg payloads to do aerophotography or experiment. It is also easy for us to replace the accessories and the cost

ServoHeli-40 aerial vehicle is a high reliability helicopter. It uses traditional helicopter configuration of single-rotor with tail rotor. The power is come from 8hp twin-cylinder twostroke air-cooled gasoline engine. The fuselage of the helicopter is constructed with aluminium. The bearings and the other parts are standard industry parts. So it is easy to buy and repair. ServoHeli-40's maximum takeoff weight is 40Kg, and its maximum payload is 15 kg. It can carry different kinds of instruments to do experiment. The rotor diameter is

station. The architecture of the RUAV control system is presented in Figure 3.

Fig. 2. Implemented ServoHeli-20 RUAV

Fig. 3. Architecture of the RUAV control system

**2.2 ServoHeli-40 platform** 

**2.2.1 ServoHeli-40 helicopter** 

is affordable.

To our flight control system, a real-time operation system (RTOS) is required for the onboard computer system. After carefully consideration and comparison, QNX Neutrino RTOS is selected as the operation system, which is ideal for embedded real-time applications. It can be scaled to very small size and provide multitasking threads, prioritydriven pre-emptive scheduling, and fast context-switching–all essential ingredients of an embedded real-time system. The applied program can be coded and debugged in the remote windows-host computers and can be executed in the airborne computer system independently, which provides great convenience during the flight experiments without modifying the program in onboard computer.
