Final year BEng project
Page last updated
20 Feb 2010, by
Martin Spencer.
6
replies
For my final year project im building a flight recorder for aerobatic flight in gliders. I will spair all the bla...
Sensors im using (with mbed cookbook/handbook librarys)
ADXL345 Acceleromiter
IDG500 Gyro
Nokia LCD
Breakout boards im developing librarys for
SP1000 barometric pressure sensor
On screen display break out board (for overlaying data on a camera feed recording the attitude)
Expect to see cookbook entrys for these two in due course!
sub-project ideas
how fast? speed from intigrating the acceleromiter data
AI - an artificial horizen using the IDG500 gyro and the nokia LCD
OSD - overlaying text/graphics on a video feed
how high? altitude from an SP1000 barometric pressure sensor. hopefully eventually with adjustable QFE setting.
Expect to see these additions in due course too!
Work In Progress (28/01/10)
Nokia screen functional using the MobileLCD librarys
ADXL345 seems to be functional, outputing on the mobile LCD. I think i will create my own library for this one.
Work In Progress (18/02/10)
ADXL345
accelerometer working
LCD scatter graph demo
RGB LED colour changing on orientation demo
datalogger graph printout from MBed file system
gyros
RGB LED demo
artificial horizen demo
OSD
simple text output over video feed on tv
LCD
fully functional - great device, great libraries!
File system
fprintfs working nicely
PC serial link
great for debugging
demos and libraries to follow.
(20/02/10)
all built up on veroboard now because i was getting sick of wires falling out! (especially when someone gets a bit enthusiastic about inputting data into the accelerometers :P )
OSD libraries in progress - got a nice demo working that takes key presses from the pc over usb and outputs them on the screen (incrementing its position each time)
this is now working with x,y coordinates on the screen and working from ascii values of the key presses - ie a putc style command would be _putc(character, x, y) and this works nicely!
ive also got cls and rst functions working nicely and backsp overwriting the last char with a blank.
still scratching my head over converting this to printf's though.
once i can figure out how to printf with it i will compile a library and integrate it into my other projects (displaying accel data ect)
How about the drive motor and prop off a model aircraft, run it as a generator to power your electronics and the voltage generated would be a good indicator of air speed?
I take it you mean run the prop and motor attatched to some part of the airframe? I think this would be less accurite than a pitot tube with a high resolution sensor, and the reason i didnt choose to calculate airspeed from pitot pressure is because i cannot make modifications to the airframe.
I take it you mean run the prop and motor attatched to some part of the airframe? I think this would be less accurite than a pitot tube with a high resolution sensor, and the reason i didnt choose to calculate airspeed from pitot pressure is because i cannot make modifications to the airframe.
I would assume the glider already has an air speed indicator, would suggest researching how its currently done, if you haven't already.
The pitch of the prop will determine its speed so you have direct measurement, with a brushed DC motor Voltage is directly proportional to speed. Showing that you investigated this as a possiblility, a lot of the assesment of your final year project is not just that it finished and worked, but the path you took, possibilities were investigated and how you made your decisions.
The accelerometer will suffer from integral error over time. Secondly any pivot sensor or accelerometer will be disrupted by the G experienced during turns, one thing pilots are taught is to use their eyes and instruments and not their sense of balance.
The glider uses the differnce between pitot tube pressure and pitot static pressure to calculate airspeed, i thought about creating another tube with a pressure sensor (somthing like the one of lego NXT) but this might get fiddley...
Gliders dont acctually have props but i see where your coming from, an aircraft with a constant speed unit would have a prop pitch directly related to the airspeed.
Good point on the accelerometer, i think some experimentation may be in order. the other issue with this is as in an inertial navigation system, it will show the ground speed and its very difficult to factor in wind as it changes with altitude so much. The acceleromiter is 3 axis though so shouldnt be effected too much by high g manouvers (i can see the gyros might be). I may well look into a pitot system some more.
Results and findings will follow when my sparkfun package arives!
Barometric Air pressure sensors from cheap weather station.
i actually got a really nice little one on a breakout board from sparkfun (SP1000) SPI interface and very very accurate!
You need to log in to post a comment
martin spencer wrote:
How about the drive motor and prop off a model aircraft, run it as a generator to power your electronics and the voltage generated would be a good indicator of air speed?