John Arne Birkeland's Posts (23)

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Crawler1 - Land based rover

3689386322?profile=originalSo, having spent the last couple of years experimenting with UAV systems I felt the need to try something that would stay on the ground. I have been fascinated by rock crawlers, the latest RC off-road trend. They seem the be the ideal platform for a land based all terrain rover system. Traction and maneuverability is very impressive.

Last week I got a HBX 1/8 scale crawler kit, and started modifying it for my needs. So far the system is FPV capable (out to about 2km), but autonomous GPS navigation is planned for a later stage.


- HBX 1/8 Crawler

- 1W 1.2ghz video link

- ServoCity Pan-Tilt system

- GoPro Hero HD camera

- 500mW 433mhz two-way radio modem

- Teensy 2.0 onboard computer / serial to servo converter


And best of all, I don't have to go out in the cold to operate it!

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Early stages of a TiltCopter

Today everybody and their dog seem to be working on a quad project. And with my own quad having reached a relatively mature stage with stable flight some time ago, I thought it would be nice to try something different.

So inspired by the full-size Osprey tilt rotor design I just started an experimental duo/tilt copter build. Frankly I am far from sure if it will ever fly, but that is what makes it fun!


My tilt design is one I used in an earlier tri-copter build. I insert a 8mm CF rods into a 750x10,5mm CF square tube and glued then together. A modified T-Rex 600 blade-holder is then inserted on the 8mm tube and fastened using glue. Finally a servo is epoxied at the side of the square tube and linked to the 600 blade-holder. Motor and ESC is a cheap TowerPro combo from HobbyKing. Cheap and easy to replace when experimenting, and the ESC has no problem handling 333mhz PWM pulses.

Hardware / software:
For control and stabilization I will use the same hardware that I used in a Quad I built earlier. A FASST R617FS receiver modified with PPM output, and the ArduIMU V2 board with custom software for stabilization and servo/ESC control.

Main body / tail:

I have yet to decide what I will do for a main body. At the very least I will need some kind of tail with a lift surface to get some balancing momentum in the pitch axis, and tail drag when in forward flight. Lots of fun experimenting to be done!

Carbon Fiber Square Tube 750x10.5mm
Carbon Fiber Tube (hollow) 8x750mm
Align T-Rex 600 Blade holders and bearings
Turnigy S3101S Servo 17g / 2.5kg / .14sec
TowerPro BM2410-9T / 18A BEC/ 1047 Prop Combo
Futaba FASST R117FS receiver
ArduIMU+ V2 (Flat)

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After having had some performance issues with 2.4ghz Xbee modules I just finished up a quick project for long range two-way communication. The system is based on HACCOM HAC-LM96 500mW 433mhz 9600 baud radio modems. Range is 2km (1.2 miles) ground level, so the system should be good for really long range communication when the plane is up in the air.

Components used:
HAC-LM96 radio modem - $52
Turnigy UBEC - 3A switched DC-DC converter - $8
Teensy 2.0 - Arduino compatible board - $19

To make it plug-and-play with my Futaba 9C radio I took the casing from an old defect RF transmitter module and put the UBEC and Teensy board inside. The UBEC is connected to the 9C V+ pin (9.6-12V) and supply 5V for the Teensy board and the HAC radio modem. Sadly the HAC modem is slightly to large for the transmitter module casing, so i had to use an extra box for the HAC modem.

The Teensy MCU converts 8 channel PPM from the 9C radio into serial data for the HAC modem. The Teensy board is my favorite Arduino compatible board, has more i/o in a smaller formfactor and a proper USB interface.

In the airplane the serial data is received by the HAC modem and either transmitted directly to the autopilot or converted back into servo PWM pulses using another Teensy board. This way I can use the HAC modems as a pure R/C control system if I need to, freeing up the 2.4ghz band for live video link etc.

To use the system as a two-way telemetry system you connect the Teensy board in the RF transmitter casing to a computer using a USB cable and either talk directly using the USB interface or use a virtual serial driver for normal two-way serial communication.

Edit: Here is the source code for the Teensy PPM decoder and rf433 transmission system.
Teensy_PPM_Decoder.pde rf433.h
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