THE RISE OF THE DRONE ERA

UPDATE 1/1/2017 Due to new legislation about drones I cannot fly my drones any more because they need an airworthiness certificate from Hellenic Civil Aviation Authority. Never mind, the costly Li-Pos are already exhausted and I thing  it is about time to move my autonomous vehicle interests to other more legal regions :) .So far so good then, I learned a lot about autonomous vehicles and most certain I HAD A BIG FUN FLYING THEM (and a huge aerial  photo collection).
    
Ok let's admit it. Can somebody who likes microprocessors, GPS's and high tec electronics stay away from drones? Nay !!!! So I entered this uncharted region plenty of fear due to the fact that I had once lost a model airplane due to my ignorance of how to fly model airplanes. However I have no fear at all to make a car - ship - airplane - drone -submarine - whatever. So I acquired some aluminum plates, bars, tubes and 3mm inox allen screws and bolts, purchased from E-bay motors , propellers, batteries , autopilots ,GPS , telemetry modules and here it is.... my first drone back in 2013 IN FLIGHT !!! 

First quad in flight  - RIP

RIP ??? How's that ? Well , I went totally unprepared, without on board pilot camera, no video link, just a simple short range bluetooth telemetry, a 1HZ GPS module  (the late EM406) which took for ever to lock , no failsafe programmed on autopilot, on a windy day to a mission which seamed very easy, very close to my house. Failsafe was a nuisance to program and once the quad  returned to launch (RTL) on his own and crashed before I understand what happened. I flew it without gps lock and when it got over 30m it drifted away due to strong winds. I tried to bring it back but since I had no colored stripes (or colored propellers) on any of the arms to know where it was heading , I drove it further away and it just disappeared from view towards a hilly forested area. Needless to say that my flying skills were (and still are) NULL. 

The broken propeller issue and Murphy’s Law

"Even if you fly in a totally bushed area your drone is going to crash on that single rock between the bushes." The frame below shows the propeller blade separating and causing a drone crash. At first I thought that responsible for the crash was some kind of RF interference. The on board video camera caught the culprit : We had an in-flight propeller blade separation.

propeller blade separating

 ...and that single rock

Quad  MK II 

After considering more seriously about flying drones I assembled the MKII. It still flies today (2016) despite a few crashes that costed me no more than a few propellers and some twisted aluminum arms and plates. Here it is:

Quad  MK II

Lessons learnt

1. Don' t use cheap 9.6 inch propellers on a 1.5kg drone - they use to flip on air (happened to me twice). 
2. Cheap batteries have unexpected behavior . 
3. Use video link and a camera for the pilot 
4. Wind velocity rises dramatically 30m or higher or when clear of trees or houses. 
5. Schedule your mission very carefully 
6. Be sure that telemetry and osd video are working 
7. Do a range test 
8. Check for RF interference 
9. Program failsafes 
10. Wait for the gps to lock.  
11. Stay away from people -cars -airplanes and generally urban areas - 1.5 kilos is not a negligible weight when falling from 70m 
12. Do preflight tests based on a thoughtful prepared list 
13. Connect the battery low warning buzzer 
14. Put a lost model module buzzer on an unused channel 
15. Write you phone number on the drone. 
16. Use different color for the drones back arms. 
17. If you 're not a competent pilot, then  let the electronics fly it for you - believe me they can do it both economically and safer too.

I decided to fix some of the problems discovered during the first and second drone development.

1. The drone should have ample space for the onboard electronics and they must be accessible without major strip down.
2. Video camera - the excellent Mobius actioncam - should be on a proper gimbal offering unobstructed front view and placed well away from the propellers.
3. The drone must be foldable and could be easily carried in a plastic tube of 15cm diameter.
4. Battery must not hit the ground, but it must be housed and protected inside a frame, and able to be moved to adjust the CG of the air-frame. (this is accomplished by using velcro straps)

The new drone named MARK V (MK V) was designed back in 2015 from scratch using a CAD software .
3mm and 0.8 mm aluminum was used for the baseplates and 1x1 1.2mm aluminum "Pi" frame for the arms.
Notice the orange colored tape on the back legs ..... 

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  CAD of quad MK V

  CAD of quad  MK V

Quad  MK V

Coming soon (?) ...

WTF is this ?
Be patient guys, if I 'm too much occupied with this blog I will never finish my projects.....Sorry

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 !!!. 

AUTONOMOUS - REMOTE CONTROLLED VEHICLE

It s a simple implementation of ardupilot ver 1.0 with a few add-ons. FTDI usb to serial interface is used to program the ardupilot, an RF data link at 9600baud transmitts positioning and other data , and standard 35 MHZ r/c equipment is used for vehicle control and activation of autopilot. Oziexplorer is used as the logging and  mapping interface (for real time position indication) via  a simple trick : Distance to home (to launch point) is injected into GGA  NMEA  sequence instead of altiude (by regenerating the sequence and transmitting it via rf )

Unfortunately due to the complete lack of suspension  and because of the ultra simple steering mechanism of the extremely cheap (6 euro's ) jeep model, when  RTL (Return To Launch) function was implemented, it  produced a funny track to home as shown in the last capture from Ozi interface.

   

The implementation of RTL function

AUTONOMOUS / REMOTE CONTROLLED WATER RESERVOIR SURVEY

Another implementation of arduino micro-controller auto pilot is the lake surveying  ROV . The main advantage of such an implementation is that ,the greatest percentage of lake area has depths less than 1/2 meter and so it's quite impossible to measure it using conventional depth sounding techniques.

A motorized (via a Graupner outboard motor) plywood platform on 2 cylindrical  floats (catamaran style),  with just 5 cm drought fits the task ,  with plenty of electronics on board such as:

• A picaxe ESC (electronic speed control)
• A standard 4 channel r/c receiver at 35 MHZ
• An Arduino board with Em406 GPS 
• An intelligent depth sounder (with rs232 output)
• A 433MHZ 9600 baud telemetry transmitter  or an XBee pro link at 900MHZ.

      and for the monitoring station:

• A laptop that runs Winxp and Oziexplorer (my favorite mapping program)
• An underwater  camera with video link (for clearing underwater obstructions) 
• A laptop for data logging - real time position indication -video capture

Surveying ROV with Gps , Autopilot, RF data link and depth sounder

Quite a big team is required for such a project. You may need :

• a 4x4 truck
• a driver
• a diver
• a cameraman
• a computer IT expert
• an electronics engineer
• a Photographer
• a GIS expert
• a computer graphics / desktop publishing expert
• Logging , mapping , GIS , video authoring and  Desktop publishing software 
• a sponsor

But the results can  be rewarding as shown in the following images :

Survey results

Survey results