EasyStar UAV with Return-To-Launch autopilot

To get the autopilot up an running as trouble free as possible I opted to use the same system as the guys from DIYdrones. They had great succes with the Multiplex Easystar and the code they release has been optimised for this airframe. So it’s better to start with a proven design, get it up and working after which I will alter it to my paraglider needs.

13.07.10 – Succes!! Both Return To Launch as well as AUTO pilot with waypoints worked. I shot 2 videos with my phone hence the poor quality.

Return To Launch: 13072010009

AUTO pilot (waypoints): 13072010010

11.07.10 – Uploaded Ardupilot 2.6. Got GPS lock back. Also removed pin D13 – design flaw. Did some ground test to look for revesed servo’s after which some  flight tests took place. Stabilisation seems to work with the standard settings. Fly by wire – no idea yet what this flight mode would do but too much wind made flight mode unpredictable. The ArduPilot Manual is an excellent resource. Throttle is manual. I still need to solder the extra wire.

14.02.10 – Uploaded Ardupilot 2.5 RC2. No luck but airframe tester seems to work OK. Configure 3 position switch as per manual for fail safe through throttle chanel.

Field setup:

  1. Check the Remove Before Fly plug is connected
  2. Power on
  3. Twitch servos to indicated startup has begun
  4. Begin looking for a GPS fix – Flash the blue LED until a fix
  5. Set the Blue LED to solid to indicate a GPS fix
  6. Twitch servos once
  7. Calibrate Radio Trims (and optionally XY IR sensors)
  8. Twitch servos until Remove before Fly pin is removed
  9. Save home location and flight settings to memory

To configure your radio, wait for the GPS to get a fix and the servos to twitch. Move your control stick to the extreme corners to recored the full range of motion of your servos. Then hold the stick in any corner for 2 seconds to exit this setup.

Need to check out debug mode and plot in Google Earth. If plane does not apprear in Google Earth try switching language to English. – csv2kml,  a free utility to convert csv files to kml format.

09.10.09 – Finally after so many little things to solve I was able to get a GPS lock. Apparently my shield is not transmitting the GPS signal to the Ardupilot. The solder joints of the small connector needed to be re-oldered. Now it’s time to integrate the autopilot to my easystar airframe.

Note: to check the GPS you can connect you uBlox to the PC directly using your FTDI cable, follow this:

  • uBlox IN -> Orange Wire
  • uBlox OUT-> Yellow Wire
  • uBlox + -> Red Wire
  • uBlox GND-> Black Wire

28.09.09 – I was able to upload the Ardupilt 2.3 code to the Ardupilot & Shield. The only difficulties (not surprisingly) which I encountered were:

  1. I had to check the RTS setting in my PC’s port settings and set RTS on close. Just follow the debugging tips at DIYdrones
  2. I had to configure the 3-position switch (“E”) on my transmitter to use channel 5
  3. Select the right COM port in Arduino
  4. Remove the GPS because of old (red) Shield version

Modifications to the Easystar:

  • ***IMPORTANT*** credit card or any other plastic card glued to the (looking from the front to back I glued it to the right section) rudder to enlarge the area
  • 1x – Motor HXT 2835 (380S) 2200kv Brushless Inrunner (same dimensions as original motor)
  • 1x – APC 6×4 propeller
  • 1x – Graupner propeller adaptor (meenemer) 6,5-10mm for 3,2mm shaft
  • 1x – Tower pro 25A ESC
  • 1x – ZIPPY Flightmax 2200mAh 3S1P 20C
  • 2x – Hitec HS81 servo
  • 1x – elapor CA glue medium + activator
  • 2x – fiber washer ID 8mm for wing (not yet added)
  • 1x – 8mm carbon rod for wings, l = 495mm (not yet added)
  • Tail stiffining (not yet added)

Free flight with the RC plane: Easystar – 18.09.09

Receiver to Ardupilot:

Channel 1 (aileron) – open – output 1

Channel 2 (throttle) – ardu input 3 (tests will be manual control directly into receiver – servo output 3)

Channel 3 (elavator) – ardu input 2 (servo output 2)

Channel 4 (rudder) – ardu input 1 (servo ardu output 1)

Channel 5 – ardu control


What do we need for the autopilot :

Everything you need for a complete ArduPilot setup

Ardupilot links:

  1. DIY Drones
  2. ArduPilot 2.x manual
  3. Arduino debugging tips
  4. ArduPilot sensor calibration FAQ