Yuri's new project (ArduCopter Quad - now 4.1.0-beta)

ArduCopter Copter 4.0
#22

I think the easiest way to rule out the LUA script is to monitor the new FC and ESC behavior at boot. If the boot anomaly is present with the new hardware, then I better disable the script until I have time to rewrite it.

I strongly suspect that the ESC is to blame for the boot anomaly rather than the script. I have a feeling that the Cube survived my goof-up just fine, but the ESC did not. I’m still wondering if something shorted, though. Even if the ESC gave up the ghost mid-flight, it shouldn’t cause a drop in battery voltage like that unless it had a significant internal short.

#23

It’s all fixed up, and if this thunderstorm breaks, I’m gonna go press my luck with a test flight.

During the teardown, I was careful to look for signs of a short, and I found nothing obvious. I’m pretty baffled as to the reason for the crash, which makes me nervous to take to the sky again, but it’s no fun to be grounded, so, with a few new parts, I’ll be back at it soon.

I decided to hard mount the FC between the top and bottom plates. The wiring is more protected there. I moved the battery to the top plate where the weight is more in line with the rotor plane, which should make it more responsive, and then I can keep any payload closer to the CG as well. I replaced the thin foam on the landing skids with some foam utensil grips meant to aid the elderly/infirmed with things like eating and toothbrushing. So far, it seems I do a lot of landing on concrete, so I feel better with the ugly but softer skid pads. I also added some green silicone caps to the right skid (same color as right-side position lights) to help with visual orientation.

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EDIT: It lives!!! First flight success. Took off in stabilize, made a few increasingly aggressive jinks to check that it wasn’t going to upset itself, checked that AltHold was useable, and then started autotune. I thought I just had the roll axis enabled, but I accidentally enabled all 3 axes. The good news is that the new configuration + lack of camera gimbal helped with endurance, so I was able to get all 3 axes done on that same first flight. There were no “failure to level” warnings, and the whole routine seemed to take less time than before. So…lesson learned…don’t mount a Cube on a soft mount! It got dark, and I don’t have any of the lights connected yet - trying out the new tune will wait for another day.

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#24

Unrelated but… Those Master Airscrew props are great arent they? I tried to balance a set but you are just making more work for yourself - they are fine to use straight out of the packet.
I’ve seen four of the 12inch Master Airscrew props lift a total takeoff weight of about 7.5 KG (or a bit more).

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#25

Absolutely related…and I have little basis for comparison, but they definitely exceeded my expectation. They are far better balanced right out of the package than some of the cheap RC plane props I’ve used. Still, it doesn’t take long to balance using the method I showed here, and it probably doesn’t hurt.

Completely unrelated, I found a free version of the sheet music to Thunderstruck, and if you want to play AC/DC on your BlHeli32 ESCs, set the gen length to 12 and paste this:

  • ESC #1
    B5 2 P4 A5 4 P4 B5 4 D6 4 B5 4 D6 2 E6 4 D6 4 F#6 2 E6 8 D6 8 B5 4
    P1 P1 P1 P8 P16
    D7 2 B6 4 P8 P16 B6 2

  • ESC #2
    G5 2 P4 F#5 4 P1 P1 P1
    B6 8 B5 8 A6 8 B5 8 G#6 8 B5 8 A6 8 B5 8 G#6 8 B5 8 F#6 8 B5 8 G#6 8 B5 8 E6 8 B5 8 F#6 8 B5 8 D#6 8 B5 8 E6 8 B5 8 D#6 4 P8 P16
    E6 2 E6 4 P8 P16 E6 2

  • ESC #3
    A4 8 P8 A4 8 P8 A4 8 P8 A4 8 P8 A4 8 P8 A4 8 P8 A4 8 P8 A4 8 P8
    A4 8 P8 A4 8 P8 A4 8 P8 A4 8 P8 A4 8 P8 A4 8 P8 A4 8 P8 A4 8 P8
    P1 P1 P1 P8 P16
    D6 2 B6 4 P8 P16 B6 2

  • ESC #4
    A5 8 P8 P2 A5 8 P8 P1 P1 P1
    A5 8 P8 A5 8 P8 A5 8 P8 A5 8 P8 A5 8 P8 A5 8 P8 A5 8 P8 A5 8 P8 A5 8 P8 A5 8 P8 A5 8 P8 A5 8 P8 P8 P16
    D6 2 B6 4 P8 P16 B6 2

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#26

I must confess to another silly mistake that cost way too much time to correct - unlike the Holybro SIK radios I used before, the ones linked in this thread have SMA connectors. The replacement antennas have RP-SMA connectors. So, there’s a great reason why the replacement antennas performed so poorly…they were physically attached but not actually connected, and I never bothered to look at the simplest solution first!

It gave me an excuse to get a cheap little vector analyzer, though (look up PS100 or N1201SA on the usual suspect sites…Amazon, AliExpress, BangGood, etc). After calibrating it, it showed the stock antennas were tuned in the 600MHz range, which makes no sense at all for their intended purpose. So I cut off the active elements, soldered up these dipole antennas, and used the VNA to tune them by cutting the elements a little at a time. With those installed, the telemetry RSSI and SNR show much closer to expectation. Alternatively, I could just use some SMA/RP-SMA adapters, but what fun is that?

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The copter is grounded except for a little testing to confirm my suspicion that I damaged a motor in the still unexplained crash. There’s a yaw instability that I cannot correct through tuning, and it appears that the #3 motor is not accelerating at the same rate as the others. I’ll throw some parts at it soon. In the meantime, I’ll do some work on the lawnmower and post those results in the Rover forum.

#27

That RP gotcha is easy to happen. It’s too bad that such a thing exists!

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#28

It lives!

I never narrowed down the root cause of the crash. I’m chalking it up to $h!t happens and moving on. I replaced the ESC with a HobbyWing X-Rotor, and I didn’t like it. It was less feature rich than the Lumenier Elite with less heat sinking, and it seemed to be the cause of the yaw instability I mentioned above, which was still present even after I replaced the suspect motor. So I got yet another Lumenier Elite ESC, and all is well. I have little basis for comparison, but the Lumenier seems like a really nice ESC.

The micro MinimOSD board finally showed up off the slow boat (fair warning, if you order from the link I gave, it takes at least a month to arrive in the US). That caused another problem…I ran out of serial ports! I had MAVLink2 on SERIAL1, FrSky telemetry on SERIAL2, GPS on SERIAL3, and ESC telemetry on SERIAL4.

So I elected to remove the ESC serial telemetry, use that port for MAVLink1, enable BDSHOT, and mess with the OSD, which was pretty easy to get set up. I flashed it with MWOSD using a 5V FTDI interface. Then I paid the couple of GBP for the license to write settings to the EEPROM. The software was easy enough to use, and it’s super configurable. I used what looked like some reasonable default profile settings and called it good enough. When the copter is disarmed, you can follow some on screen prompts to use the transmitter sticks to navigate a series of menus.

Because I’m interested in freeing the limited serial ports in other projects, this was a perfect place to experiment a bit with UAVCAN. The Here+ V2 looks like it has an option for CAN bus operation, but it appears that was a future roadmap thing and was never actually enabled. If it’s supposed to work, I couldn’t make it happen. But I did find the mRO UAVCAN Node, which will convert many ArduPilot compatible serial and I2C devices to the UAVCAN protocol. It was entirely unnecessary for this project, but I wanted to experiment, so I ordered one. Once I set CAN_D1_PROTOCOL = 1 in addition to the settings on the documentation page, it worked right away without further setup, including RTK injection and the integrated I2C compass. The notification LEDs on the Here+ aren’t working, even with the UAVCAN bit set in the NTF_LED_TYPES parameter, but I can live without that. With SERIAL3 freed up, I reconnected ESC serial telemetry there. I was also able to split the button pins off of the Here+ connector and connect them to their previous locations on the GPS1 connector, so the hardware safety switch still works, even with SERIAL3_PROTOCOL = 16. It was a really interesting exercise and may prove handy again someday!

I have some more ideas about video capture, but I’ll save that for another post. This one is already longwinded!

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#29

I would say i agree and nice build BTW.

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#30

Perhaps one of you following this can un-muddy the ESC telemetry waters.

As I understand it, BDSHOT telemetry is quite a bit faster than ESC serial telemetry and should offer a significant performance increase, particularly with respect to harmonic filtering. However, BDSHOT is RPM only, where ESC serial telemetry often includes voltage, current, and temperature in addition to RPM.

If I read correctly in the BDSHOT support topic, there is no harm in enabling/monitoring both BDSHOT and ESC serial telemetry, and they do not conflict with one another.

Do I have that about right, or is there more to the story?

#31

You can do both at the same time, just make sure TRATE is low (the default of 10Hz is fine)

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