Hello DIY Drones!
I'll start off by noting that I am new to your community but have been involved with several DIY drone projects over the past few years. Lately I've been playing with the Pixhawk2 autopilot but have been having several problems. From analyzing the log output of both he telemetry and the data flash logs sometimes I get lost radio contact, GPS errors, etc and I'm getting very frustrated with the reliability and fail safe safe but don't know much about how to improve them. I have a degree in Electrical Engineering and also know how to program so I would very much like to learn more.
Doing some basic homework and talking with 3DR tech support recently suggested to me that not many people are experiencing these problems. I'm unable to get a firm grasp of whether or not I am experiencing known bugs or if I'm just plain doing something wrong.
I started learning to pilot using non autopilot boards such as the KK2 which I loved. I have crashed my fair share of both piloted and un-piloted drones and pretty much know when it's my fault or some hardware or software glitch.
However I experienced a problem that resulted in a very bad crash which totalled the craft, gimbal, and other accessories. I was unable to recover the Pixhawk and the memory card on board was completely damaged as well.
From what I could tell the craft (a 3DR IRIS+) got a confused GPS location. The map on the APM Planner showed the craft being approx 100m away from where it physically was. The craft became un-responsive (from what I can tell it lost radio contact) which also bugs me because it was line of site. I saw the craft slowly start to drift (loss of GPS hold) and eventually crash while I desperately tried to establish control or at least an RTL mode - which I later found out would have failed anyway due to the home base being reported incorrectly. Never was the craft flown in AUTO mode on this flight with the exception of my failed attempt to set the RTL which the tLogs confirmed did not get set!
So now I am researching the DJI Phanom 4 (I love open source but I'm looking for something that at least I can feel confident that when I crash its my fault and not some glitch). It has GPS + Glonass which makes me think it should be better. However, certain sites claim that the DJI P4 still has flyaway issues. Ive had discussions with 3DR support and they claim that technical issues have been largely solved as the software gets updated but this hasn't been my experience.
I also just saw a new thread on the Pixhawk2 which I am very excited about. Perhaps I will build a new drone with the new Pixhawk2 hardware when it comes out - which I haven't been able to discern.
What I am asking from the community is the following:
1) Have you experienced any hardware or software glitches that resulted in loss of control?
2) What are some ways to minimize these risks. For example if I fly in ALT HOLD mode only will that be effective even with high GPS HDOP since its much easier to calculate altitude instead of a 3D Position fix? Or will the autopilot still fail in the case of poor GPS signal due tot he fact that it tries to get a 3D position fix first then set the mode to only maintain altitude?
3) What are the most reliable autopilot boards out there? I don't want to make my own and from what I can tell both 3DR and DJI make the most reliable products (but it doesn't seem to be where I want them yet).
4) is the Pixhawk 2 better in terms of reliability? It looks great from a smaller form factor (weight savings, more power efficient [hypothesis], less clutter, better sensors, etc) but is it more reliable?
5) Regarding batteries. I like to have the old style batteries with the simple connectors because they are cheaper and I can choose alternate products. I use the 3DR branded 5100mah batteries. I've noticed that both 3DR and DJI packaged a micro-controler (I hope and assume) onto the newer batteries for the SOLO and P3 and P4 products but from what I can tell if you are educated in the art of properly maintaining Lithium Polymer batteries you won't need to rely on these more expensive products (another reason why I'm going to lean toward home built vs pre-packaged).
6) I've heard that DJI's light bridge technology is great. I believe that 3DR uses something similar over wifi (please correct me if I'm wrong). I don't currently fly FPV but would love to get started and a concern would be video quality, reliability, lag time, maximum distance, etc.
Finally - a little out of topics for this thread but people have said that the DJI propulsion systems are able to get more flight time than the 3DR products. I'm wondering how this is possible. Is it a matter of power management and efficiency? Weight? Pushing the battery up to the edge in terms of limits? What tips and tricks do you use to get maximum flight time. I've experienced several problems with the low voltage cutoff not returning to launch soon enough so I set very conservative limits and limit my flight time to just over 10 minutes. I see DJI advertising 28 minutes of flight time which is almost tripple! Even flying conservatively if I can get a solid 20 minute flight that would be amazing. OK signing off and seeing what happens.
Thank you!
Replies