Maidened Y6 - what I looked for

3689586037?profile=originalJust a bit of a monologue about what I did on my maiden, and I what I looked for before I started flying it properly. Some people just go full sticks right after arming, but I prefer a more cautious approach.

Step 1: All the calibrations done - radio, compass, compassmot, flight modes etc. Importantly, only 3 flight modes configured - stabilise, alt hold and Loiter. RTL was temporarily replaced with autotune (more on this later). Laptop connected up for full telemetry.

Step 2: Armed, and spooled up to near hover; to test if it will take off in a stable manner. If it tried to flip to one arm, something is wrong. It passed this test, so onto the next one.

Step 3: Lift off above the ground effect, and wait. Normally, this is when you get an idea of whether the PID's are out. Mine were - P and D were both way off, with the Y6 bouncing/warbling away. I landed immediately.

Step 4: Tweaked the PID's to get a stable flight. Not looking for optimal at this point - just getting it to within "the envelope". Do some basic maneuvers, such as figures of eight, and some throttle squirts. If it responds ok, move onto step 5.

Step 5: Checked the batteries, and fired it up in stablise, and engaged autotune. I was very nervous about this, given the problems I've had in the past. I ran it in stabilise, and it went....ok!

Step 6: Save autotune settings. Check over the motors, props, ESC connectors. Check voltage. Arm...and slowly explore the autotune settings. And for the first time ever...it's worked! It's tight when you jab the sticks, It holds a stable heading, and holds a steady attitude. Checked yaw etc. I switched to alt hold to remove one vector for analysis, allowing me to concentrate on the roll/pitch/yaw. It handles well, but it has a tendency to loose altitude.

Step 7: Start to push it around. More sticks, more speed, more power. Some straight up near-full-power ascents show a tendency for the tail to drag. More on this later. But on the whole its flying well! Refreshed PID settings screen on laptop, and was surprised to find it's really tuned down P and I, and D was quite high. Hmmm. Did a test run of loiter...I was quite worried about this, with a compassmot of 24%. I needn't have worried. It was absolutely rock solid. However, in stabilise, it moves about a surprising amount, even in a 1kph wind.

Step 8: Finish the pack(s), and head home, and start the log inspection. Noticed that roll was pretty tight, but there's a bit of overshoot. And one roll event which didn't match inputs. Pitch...has more issues. I suspect I know the reason - the same reason it was dragging the tail on burst accelerations - a draggy 4 or 6 motor. These two tail motors were consistently spinning faster than the front four as well. More testing to be done here. Maybe a CoG issue.

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Step 9: Verify vibes. And it's not a good story. It hovers ok, but apply some real juice, and the vibes shoot up. Way up. Way beyond the +/- 5 I consider acceptable. Again, I suspect this is a dodgy motor...the trick will be trying to find it - and given the tail dragging, I think it's one of the rear motor.

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So the next flight will be about tweaking that last few percent, and checking out that possibly dodgy motor! But all in all, the maiden went ok ;-)

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Comments

  • Just want to say thanks for this post Euan, it was instrumental in getting me off the ground!

  • tuning P using the logs seems straightforward.... too low P value and the values will undershoot. too high, and they will overshoot or resonate around the desired value. 

    how about derivative and integral tuning using the accelerometer logs? I still haven't seen any easy to follow tutorial on how to tune these parameters. Does anyone have a solid, systematic approach for tuning these?

  • To follow Scott's comments above, this kind of blog post will help newbies get a better idea of what they have ahead of them, the many potential points of failure in their system, and offers the wisdom of a cautious, incremental approach before trying to do everything at once on the first flight. So I added a link to it on this page, and this page. Thanks for the post.

  • What's your CoG like? With 2 x 4500 4S, this feels pretty top heavy...is yours the same?

  • MR60

    Nice procedural approach.

    Like you experienced, I found on my quad that auto tune lowers P too much and increases D too much ( too much versus a manual tuning that feels right). Is there a pattern or is it pure coincidence?

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