I have just completed my rebuild of The Groundhog hexacopter with a Pixhawk2  and NVIDIA Jetson TX2 companion computer.  This is in preparation for the coding blogs I am posting and further work integrating depth cameras and machine learning.  For those interested, details of the build are posted on my blog at www.mikeisted.com.

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Comment by Lyn Rees on August 25, 2018 at 5:25am

Nice build mate. Any reason why you didn't use the RFD 868X for control, seeing as it has that facility?

Comment by Mike Isted on August 25, 2018 at 6:27am

Hi Lyn,

That's a very good point and thanks for your kind words. I may well build on that angle in the future.

In the first instance, part of this is to investigate exactly what the RFD brings to the table, my main interest being  reliability in the field. 

Which brings me to my second point.  A major cause of drone crashes is the loss of communications, so I am interested in having several ways of communicating, rather than routing everything through one device.  It's the same reason that the receiver has potential for dual redundancy (and I may also add a last ditch connection to the iridium network!).  

I'm happy to accept I'm paranoid on the safety front, though!

Comment by Lyn Rees on August 25, 2018 at 8:01am

Totally understand your reasoning on the safety front. I myself fly a coax quad, along with fixed wings, for the same reason it also has dual power supply from the twin batteries through the full system. the only thing I worry about now is the FC. i believe Marco is working on dual FC at this time.

Comment by Mike Isted on August 25, 2018 at 8:15am

I have a prototype triple redundant system on my desk... (allied to a TX2 as well)...

Comment by Lyn Rees on August 25, 2018 at 8:26am

Be very interested in knowing more:-)

I live in RCT. Perhaps we will bump into each other one day and swap thought:-)

Comment by Mike Isted on August 25, 2018 at 9:24am

Also working on dual power supply - problem with just connecting in parallel is that if one goes short, it takes out the other.  Connecting via a high power Schottky(?) diode should do the trick, I think.  Need to do a little reading up, but that's the thought.

Comment by Lyn Rees on August 25, 2018 at 11:31am

The cool thing with the co-ax is I can drive the motors 4 + 4 so the main supply powers (2 x 10'000, 6S) never meet. The multi copter has a better than 2.2:1 power to weight ratio. In this way I can afford to lose an entire side (4 motor / prop combinations) without loosing the copter (control is compromised quite heavily if all 4 shut down however). The secondary feeds (12V, 5.3V etc) from both custom power boards are protected via an "ideal diode". In this way I can dual feed any item without worrying about one supply taking out the other in the event of a failure!

Comment by Mike Isted on August 25, 2018 at 11:36am

Very nice Lyn.  I'm working towards a heavy lift octacopter, but could still be persuaded to go 4+4...  

I have whole bunch of questions, but maybe this is going even more off-piste.  You on LinkedIn?

Comment by Lyn Rees on August 25, 2018 at 12:27pm

The co-ax IMHO has all the advantages of an octo (I have a 1000mm one of those as well that I will,hopefully, get around to finishing some day) and no disadvantage for the reasons mentioned above. It also the ability to use larger props for a given frame size. I designed my own co-ax following known principals (i'm no expert) as this came about following a crash and subsequent fire with my first quad. I do use Linkedin at work but not at home at this time.

Comment by Tiziano Fiorenzani on August 30, 2018 at 6:41am

Mike, I enjoy following your blog. You should definitely put up the kit for sale as a bundle ;-)


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