AttoPilot Users Group

Smarter Cheaper Faster

In early March I got involved in a "proof-of-concept" project that was to use an RC airframe and an autopilot system.
Goal of the first phase:
1) Demonstrate the ability of an RC airframe under autopilot control to perform tasks such as fly a specified path at a set altitude and airspeed, and initiate an event at a designated point along the flight path.
2) Learn as much as possible about the "care and feeding" and the potential uses of the AUV system.
3) Do all of this at as low an initial cost as possible.

After reviewing some material obtained by typing "UAV" on Google, I spent most of the effort in "RC Groups". I read almost all of "Beta Details - dmgoedde", "ArduPilot 2.0 software released --", "Picopilot", etc. I looked at many of the websites listed in "Sticky: UAV Links" and came to the conclusion that there are 3 main groups of autopilot systems suitable for use in RC airframes.

1) The low cost - labor intensive "open system" types.
2) The very expensive "commercial" types
3) The "under $1000 ARF" type.
I chose from door # 3 - the AttoPilot 8.1 by Dean Goedde.

Limited funds meant we had to use available airframes, computer, and RC systems.
I have an Easy Glider that I used for FPV, a Futaba 9C RC system on 72Mhz, a video system with both 900Mhz and 2.4Ghz transmitter/receiver systems. Another team member donated the use of an HP laptop.

By mid March we were ready to go.
The Easy Glider had been modified for the FPV camera by placing a rear facing brushless motor on a pylon, putting the elevator and rudder servos near the tail, and carving out foam were needed for the video transmitter and the relocated RC receiver. BTW - my inspiration for the Easy Glider modifications came from "http://www.rcdon.com/html/the_sail-cam_project.html". Lots of good information there.

We decided to use the Easy Glider as a "flying breadboard". Implementation of the systems would be practical, not cosmetic. We sure met that goal - it' one ugly aircraft!


The RC receiver is strapped to one side of the pylon and the AttoPilot strapped to the other. A tower was added for the XY sensor. The GPS antenna was stuck to the fuse at mid-tail, the MicroCard holder and Z sensor were stuck on the left side of the cockpit. The ESC was stuck on with Velcro.



The system was interconnected as described in the "manual". None of the leads were cut. All excess wires were bundled and slip tied. We used a lot of double sided rubber tape, Velcro, blue masking tape and some CA glue.

The AttoPilot as received is a complete system. All sensors, all wiring, all software, and almost all the documentation are included. The documentation and software are provided on the MicroCard that will be used for flight control and data logging.

The CGS (Ground Control System) is outstanding! Much better than I thought it would be. It is used for after flight analysis at first. It will be used for realtime monitoring and control in the future.


The integration of the system with Goggle Earth was another very pleasant surprise. A plot of the flying area can be used to create the WP (way point) file and after the flight, the GCS can convert the LOG file from the flight to a .kml file that is used to plot the flight on the same Google Earth presentation.



HOW STEEP THE LEARNING CURVE or WHAT ATTOPILOT TOUGHT ME.

Read the documentation over, then read it again.
Be very careful when editing the SET and WP files. Minor errors can cause major problems.

I bought extra MicroCards. CARD1 is used for the initial "Test Mode", CARD2 is the flight card and CARD3 is a backup flight card. The new MicroCards need to be formatted and labeled. The card supplied with the system was preserved and protected in a vault. Not really, but I did put two complete copies of it on the home computer. One as backup and the other as the working copy for access to the software. That card is stashed is a safe place. Study the files from the supplied card very carefully. You will need the information contained in each one of them at some time.

The tuning process is very iterative. It involves adjusting some of the parameters in the SET file and possibly the adjustment or relocation of some sensors. Make sure the pitot tubes are properly installed and clear. It will take several flights just to get in the ballpark. Don't try too many changes at one time. Electrical noise can be a problem. I had to move the XY sensor away from the ESC and Motor wires. I also used a toroid around the ESC wires to the AttoPilot.

The "flying Breadboard" is to be used to evaluate all of the components of the UAV system before transferring to the next airframe. We kept a record of each flight and the changes made between flights. I made up a check list and mission log form.


UAV MISSION CHECK LIST

FLIGHT _____


DATE: ______ AIRCRAFT: _______________ LOCATION: _________________

TEMP:______ WIND SPEED/DIRECTION _____/_____ CLOUD COVER_________


AIRCRAFT PRE FLIGHT:

[ ] Control Frequency/ clear (pin) _____________

[ ] Check and record flight battery voltage. _____________

[ ] Check and record other batteries: _____________

[ ] Range Check

[ ] Verify proper CG

[ ] AttoPilot SD Card # installed _____________

[ ] RC Transmitter set to proper aircraft

[ ] AttoPilot mode selection verified: RC, ARC, LARC, AUTO

[ ] Verify number of GPS satellites ____________

[ ] Verify pitot and static tubes are clear

[ ] AttoPilot mode set to RC

[ ] Check aircraft control surfaces move are in correct direction, deflection

[ ] AttoPilot mode to AUTO, Check control surface movement is correct for Roll and Pitch

[ ] AttoPilot mode back to RC

[ ] Take off and start timer

[ ] Post flight. Record flight battery voltage. _____________






MISSION LOG

Aircraft Configuration: ______________________________________________________
________________________________________________________________________
________________________________________________________________________

Aircraft changes since last flight: ______________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________

Software (SET/WP) changes since last flight: ____________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________

Payload: _______________________________________________________________
______________________________________________________________________
______________________________________________________________________

Mission Objectives: ______________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________

WP File configuration: ____________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________

Flight Data: ____________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________

Additional Notes: ________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________

SET File logged as: _____________________________________

WP File logged as ______________________________________

LOG file logged as: _____________________________________

form updated 05/17/09

You don't need to have a laptop at the field but it makes the tuning process go much faster.
Make sure there is no LOG file on the MicroCard for the first flight of the day. After each flight you should rename the LOG file. If you don't the second flight will have its data appended to the same LOG file as the first flight. That is OK but that can make the Google Earth plot very busy.

All of the first phase goals have been met.
1) Demonstrate the ability of an RC airframe under autopilot control to perform tasks such as fly a specified path at a set altitude and airspeed, and release a streamer at a designated point along the flight path.
2) Learn as much as possible about the "care and feeding" and the potential uses of the AUV system.
3) Do all of this at as low an initial cost as possible.

It has taken us 30 flight to get there.

Next - add the 9XTend TX/RX modems to the system for real time flight display and control
Add the video system and test for compatibility.

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