This project utilises the concept of using the existing APM and configuration tools and a seperate radio link to send back specific telemetry data, in this case depth and a seperate GPS marker so that no code on the APM needs to be changed.

I see this as an advantage doing two links as it means that those that are not comfortable doing a lot of code changes can play round and develop links on the side no matter what form of drone or scientific data add on needs to be applied.

The seperate telemetry unit utilizes a arduino running the new software serial code which time slices between the MTK GPS running at 9600 and a Cruzpro depth sounder running NMEA-0183.  The seperate radio link is currently a radiometrix spaceport modem and is sent to a text file. Below is some of the text file sent via the long range modem.  The telemetry is untouched for the APM and is sent back via X-bees.

,LAT=,-40.168949 ,LON=,175.363296 ,SAT=,9 ,Depth=,$SDDPT,002.1,*7A
,LAT=,-40.168949 ,LON=,175.363327 ,SAT=,9 ,Depth=,$SDDPT,002.1,*7A
,LAT=,-40.168949 ,LON=,175.363327 ,SAT=,9 ,Depth=,$SDDPT,002.1,*7A
,LAT=,-

Currently all the links and the code have been tested and the boat (the largest deep V hobby king could provide) arrived yesterday so now we start the hardware.

Pictures below are of the two positions of the two seperate links as they need to be a close match.

Many will know of people who through illness or injury who used to fly etc... and no longer can, would like to be able to do so again (I am in the above). 

Our project (my wife is now my hands) is to use a head based sensor and the APM to achieve some form of control.  If there is anyone interested in this project and some genuine interest I'm sure my lovely wife will add to this blog.

To date we have built a stable quad with our own cnc cuttout components and Multiwii as the basic platform which will be moved to the APM once we have the headset (2 x accelerometers, 1 acting as a static reference for the dynamic accelerometer) finished and working as a PPM stream into the trainer port on our Hitec transmitter.

I know there are head trackers avaliable but these do not inject the full 5 channels we need.  We are currently trialing some arduino code by Ian Johnston for the full 6 channel injection. Photo below is in level flight hands off. As above any interest feel free to comment. (the camera must have been at the right shutter speed to show the props as stopped)