Sunday, July 29, 2012

Testing the IMU on the airfraime

Wings and fuselage have been merged now, servos and control surfaces linkage are installed.  I replaced my own IMU code by a implementation from Sebastian Madgwick he developed during his PhD. His C# implementation is significant faster than my implementation and much more accurate too, especially for low update rates. Simple PID controllers are used to calculate the control surface angles.



More information to Sebastian Madgwicks implementation you can find on: www.x-io.co.uk

Thursday, July 19, 2012

Some Photos


The following photos shows the naked airframe and the mostly finished mainboard. From left to right you can see the GPS-receiver, barometer, IMU-board (with 3-axis gyro, 3-axis accelerometer and 3-axis magnetometer), pilot tube pressure sensor, mini SD-card, CPU and step-up converter.


Ground Station Hardware

The Ground station hardware has been finished. It consists of a 20 dbm RF-modul (RFM22b) mounted on an old Wifi-PCI-card, a controlling board (FEZ Panda) and a 11 dbi Yagi. Design and calculations for the Yagi are made by Michael using VK5DJ's YAGI CALCULATOR.


Software

On CodePlex the current state of the software is online. The software is written in C# for .NET (ground station) and NETMF (plane onboard cpu). Most hardware drivers are already finished.A short overvew of the software parts:
  •     Hardware Drivers
  •         BMP085 Barometer
  •         L3G4200D Gyro
  •         LSM303DLM Accelerometer/Magnetometer
  •         SkyTraq Venus6 GPS Recever using binary protocol
  •         RFM22b RF-Modul (20 dbm)
  •         Temperatur (in progress)
  •     Analog input handling for pilot tube, battery current and voltage
  •     IMU 9DoF - Sensor merging
  •     Navigation (in progress)

The Plan

The aim of this project is to create a plane that can be lifted up to an altitude of 10 to 20 km by a helium filed balloon and fly back to the start place autonomously.

At the point the plane reaches the target altitude or the balloon bursts the plane cuts the line to the balloon. From that point the plane cruses back to the lunch site guided by GPS. To handle the landing at the lunch side a parachute opens 100 m above the ground and brings down the plane safely.

This project is essentially inspired by Art Vanden Berg who conducted a similar project successfully 10 years ago. Today where components like electronic gyros, compasses and accelerometers are standard parts in consumer electronics things changed compared to the year 2001. Such components are easily and cheap available. This project aim to realize a very lightweight plane with low energy consumption and low components costs.


Main components are:
  • Onboard CPU
  • IMU (consists of gyros, accelerometers and compass)
  • GPS-Receiver that works above 10 km altitude
  • Barometer for altitude indication
  • Temperature sensors
  • Pilot tube for air speed indication
  • Long range transceiver for telemetry
  • Servos for elevons
  • VGA-camera
  • Line cutter
  • Parachute ejection system