Enduroquad Success

2 EnduroQuads ready to take flight. Both carry 20 Ahr of 4S. Ours, on the left, has a Tarot 2-axis GoPro gimbal as payload and the one on the right has a 6600 mAhr 4S standing in for a Sony a5100.

Well, as I mentioned in my Vibration Consideration post, I have been working on new iterations of an endurance quadcopter. Today I cleared the final hurdle in declaring it ready for use: I flew it in Auto. As I mentioned before, I have seen this quad (and others) descend in forward flight while in Loiter or Alt Hold, so I was a little worried about how auto would go. The only thing to do, though, was to give it a shot. So, I gave it a plan to fly a grid over Davis Field and let it rip. It was basically flawless. After it finished and began loitering at the final WP, I restarted the mission, and let it go again. Then I put it in RTL and let it autoland. Finally I restarted the mission, took off in Loiter, switched to Auto, let it run, and then did an RTL and autoland again. All in all, it was really nice with no significant altitude loss at a 6 m/s cruise.

Screenshot showing 3 auto flights using the same flight plan. Note the excellent agreement between all flights (orange, green, and pink)

Here are my more detailed notes:

• Upping rate_yaw_P to a the healthy value of 0.28 (from a default of 0.2 and above the "maximum" value of 0.25) fixed the issue I had with the nose wandering around. I'll say, this behemoth needs some huge PID values to make it fly well.
• I did observe altitude drop at the end of transects which is well known to the APM community. This seems to be a physical barometric pressure issue and there doesn't really seem to be a workable fix for it. I have never seen it present a problem, though, as it has always been a controlled loss of about 1-2m altitude which is then regained.
• Copter 3.2.1 doesn't like to land on a slope. In both autolandings I had to switch to Stabilize with the throttle down as the landing detector didn't kick in with the slope there. The changelog indicates that this may have been fixed in 3.3 (they added "improved landing on slopes"). I will find out when I test the bigger EnduroQuad which has 3.3. I will also likely upgrade this one to 3.3
• Takeoff in Loiter is quite nice. The devs have done a considerable amount of work with this in recent releases and I now find it to be a less dramatic way to get out of ground effect than punching the throttle in Stabilize.

So, that is pretty much it. My plan for the rest of the week is to get a few more hours of time on our quad and get a few Auto flights in on the bigger quad to convince myself that they are both 100% mission capable. Then it will be on to all sorts of fun projects like using TIR imagery to census lions, tigers, and bears at the NC Zoo and deer at Pilot Mountain. We are also planning to use it to identify energy leaks on some buildings around campus.