Σάββατο, 10 Δεκεμβρίου 2016

AUTOPILOT MEGA (APM) - Now, we 're getting serious

Well beyond ardupilot I (best known as ardupilot legacy) , the excellent APM 2.5 (or 2.x) hardware and corresponding firmware gives the opportunity to fully explore the potential of modern mems devices and other electronic modules. In particular , using modern ultra fast and cheap GPS modules from China such as Ublox NEO 8M we can develop UAV's with astonishing position hold and track follow accuracy.

My new (gen II) auto piloted car is based on a simple wireless remote controlled jeep given as a NiCd battery discharging device with a SKILL portable drill. I changed the motor driver with a quick-and-dirty perf board with an ATtiny2313 and a L293D to control steering and traction motors.

ATtiny 2313 and L293D dual channel PWM motor driver

Then I (over) loaded the little toy with an APM 2.6 autopilot, a 5V power module,a Ublox GPS, 915MHZ telemetry module, 2.4Ghz R/C receiver, servo camera (or antenna, machine gun, whatever) gimbal, 5.8 GHz video transmitter and a 3c 2200mAh LiPo battery. It finally looks like this :

APM inside

Without camera or 5.8 GHZ video transmitter 

This particular rover is a fine platform for developing and testing autopilot modes, ground control stations (GCS), PID controller behavior, GPS accuracy, R/C remote - telemetry - video range , power consumption and electronic interference between modules. Its maximum speed is 0.4m/sec but with an 2200mAh LiPo battery it can travel for hours with everything on, and you can’t lose or crash it. You can hardly wear its "tires" too.

Let's see it in action at night with an automatic mission with 4 waypoints. Using the Ublox 8M GPS (16 satellites HDOP 1.35m) we get the following astonishing results regarding the track repetition accuracy of a such an economic combination of hardware and firmware !!! (even multipath issues are not affecting GPS performance -what else can someone ask ?)

Night testing of GPS - autopilot accurancy

On Michael Oborne's excellent Mission Planner GCS we can clearly see the telemetry data and 5+ track repetition accuracy.

  Ublox 8M GPS impecable performance  


 Ublox 6M GPS has a decent performance as well 

This little thingy has travelled literally lots of kilometers without any issues. Just charge the battery and go on. You can 't imagine the joy you get when seeing this little fellow driving on after one and a half hour, hitting one waypoint after the other with more than 60% of battery remaining !!!.