More auto tuning

After my last adventure discovering the in's-and-out's of auto-tuning I contacted my mate in Canadia DWGSparky for advice on taming the Skywalker X5 and getting it 'tuned'.

As always he had lots and lots of advice, I soon learnt that the auto-tuning was one of the most important parts of setting up the APM functions and that sometimes they can take quite a while to get right.

Armed with my new found knowledge I set back to the flying field, this time with Stu to help monitor Mission Planner.

Unfortunately we had the same troubles as last week. After many tests the auto-tune mode of virtually unresponsive and the RTL would send the X5 into a terminal death dive.

Frustrated I gave up flying for the morning and sat back drinking my iced coffee watching the other boyz fly. At least the scenery was calming.

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Auto tuning

It's been nearly two months since I last flew the Skywalker X5 (been busy working on the house and garden) so I took her up for a re-familiarisation flight to see how rusty I was after such a long break. It was like riding a bike, no problems at all. :)

Now that the airframe tuned for basic RC it's now time to work on the auto-tune function to get the APM working efficiently. So today the task at hand was to get started on the auto-tuning function.

I started by assigning three flights modes, manual, stabilize and FBWA to see how they performed. Stabilize seemed to work quite nicely, it took the edge off flying the 'squirrelly' X5 and the FBWA mode seemed to work with the bank limiting obvious. Once these flight modes were tested I bought her in and re-assigned the stabilise mode to Auto-tune and FBWA mode to RTL.

Thing's didn't go too smoothly this time around. The auto-tune mode was extremely tough to get any response from, when I changed into the mode the X5 became extremely sluggish and almost impossible to manoeuvre. I moved the control surfaces hard left, hard right and it took several seconds before the X5 could turn around. The speed at which the X5 flies across in front of me meant that I could only attempt an auto-tune mode for about 12-15 seconds before turning it off to do a 180 and fly back in the other direction.

I really wasn't sure if I was getting any 'tuning' done so thought I'd see what happened when I flicked to RTL. The first time I tried it seemed to work, with the X5 changing direction and heading over roughly to where the RTL point on the Mission Planner was set, however it overshot the position, did a slight turn and started to fly away. I panicked and switched back to manual mode.

When I tried RTL again instead of heading to waypoint, the X5 pitched up, did a hard turn and then nosed hard down and increased throttle. I switched back to manual immediately and bought her in.

It seems that auto-tuning was going to be a little tricky.

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First flight with APM

First flight of the Skywalker X5 with APM

Today was the big day, the first test flight for the Skywalker X5 with the APM mounted ..... and it all went superbly! I didn't jump in the air once all the tests were complete, but I did let out a loud WOO HOO.

Firstly I took her up and re-trimmed her in manual, it was a little gusty but got there in the end. Once I was happy with the trims, I tested changing mode to 'stabilise' when I was flying into wind and at altitude. All went fine, there was some difference and she felt like she was definitely tracking a little better. After that I tried 'FBWA' mode and found that one a little un-nerving. The Skywalker X5 is a squirrely thing to fly and when I suddenly didn't have as much control authority as I am used to I got a little scared. Anyway the bank seemed to stop and hold at somewhere around 40 degrees I'd guess and similar with bank, so FBWA seemed to work.



All the gear needed, X5 with APM installed, laptop with Mission Planner, 9XR Tx and backpack

I then bought her in and had a break while Harry and I checked over everything. By this time Stu and Paul arrived at the field so at last I had someone who could monitor the Mission Planner while I flew. I changed the FBWA mode to RTL and took her out for another go. Oh, I made sure a new home point was correctly placed in the Mission Planner and loaded onto the APM.

The launch was a little scary (its ok I was expecting it) as I had just trimmed her for level flight. It was just a slight nose down launch until she got about a foot off the deck then she powered away and climbed just fine.

We went through the first 2 modes again to make sure all was right, and Stu was calling out the G/S, altitude, flight mode etc every so often, all seemed to be working well as what was happening in the air correlated with what was on the laptop screen. The Mission Planner did seem to freeze a few times, but within a few moments came back to life, still not sure what that's about. The time was right so I clicked the RTL (again on and upwind leg and at altitude) and guess what?...... she took herself back over to the position I had marked on the map and started circling! Absolutely exhilarating to watch but again a little un-nerving when you don't have to be hyper focussed on keeping the flying brick airborne. It was only a quick RTL test I didn't have the courage to let it go on for long and shortly after I decided to bring her in, "quit while I am ahead" is exactly what I said to myself!

A massive thank you to David DwgSparky from DIY Drones for all his guidance with setting up and tuning the APM, I really don't think it would have been a success without his help and also to Stu for his expert monitoring.

I'm guessing I'll be doing a few more flights just like this one to get comfortable with the different modes and confident the RTL is going to work correctly and for extended periods of time. This is turning out to be a very exciting adventure.



My trusty co-pilot Harry helping to do pre-flights

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Mounting the APM, config with 9XR and bench testing

APM mounted 270 degrees off Skywalker X5 axis

I installed the APM into my Skywalker X5 a few days ago. There was a little 'faffing' around getting it all to fit the rear bay of the X5, but in the end it seems to fit well. I have it mounted to the airframe on a small plywood board, the APM is stuck to the board using the 'anti-vibration' sticky foam pads.

So this morning I took some time to go through the initial setup of the APM, I found it quite straight forward, although I feel the documentation is still a little 'light on'.

First step was to hook the Rx into the APM. Usually I have throttle on Ch1, elevator Ch2 and Aileron Ch3. However APM needs throttle to be on Ch3 so I had to do a switch around, no big deal but I couldn't find anywhere on the APM Wiki that actually tells the user to do that. Is it common to have throttle on Ch3 and it's just me that is doing it all 'arse about'?

Initial Setup
The latest version of Mission Planner has nice little 'initial setup wizard', once I had my Rx talking to/through the APM I clicked on that button and ran through all 16 steps. I had to calibrate the accelerometer, the compass, the radio, set the flight modes, let it know what extra sensors where installed and more. You'll see a photo of my 9XR and the settings I have for it below, I hope it saves you some time.

The radio calibration proved to be the toughest to get just right ....

Flight Modes
Next I went through and tested the flight modes. For the first test I thought that I'd use manual, stabilise and FBWA modes. If all goes well with them I'll go to mode 'RTL' and then to 'Auto'. Manual mode worked just fine, all inputs were as they have been for the last few weeks. The 'stabilise' mode however was giving me some 'curley' results. The manual inputs (when in this mode) were just fine however the actual stabilisation was completely off ..........

PID's


Failsafe

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