Blackbird 180 - an exercise in Quatos and KISS ESC

[Mullet]

Harry,

I had issues with the Char Set as well. I ended up having to revert to a standard firmware in order for the Char Set to load properly. Then I reloaded the AQ based OSD firmware and things looked correct. No matter what I did I couldn't get it to load whilst Kisssys' firmware was the OSD version.

If you're using the standard Minim OSD I think you have to have both sides of the board powered to flash the Char Set. I used the Micro version, which only needed one power source.

[Mullet]

The next step is to build everything up. This is actually the easiest part in my opinion. My approach is to start with wiring everything up to the PDB first then make adjustments to the length of wires to each individual ESC or other part. I had already determined length of wiring for my OSD system, as seen in my previous post, so I didn’t need to do that.

Here is a picture of the FPV system and PDB before it was really wired up...

The 2 pin pico connector will be wired to the 12v reg on the PDB. The black and red wires coming from the Micro Minim go to the 5v reg. Where it says LED on the upper right of the PDB is actually the same as the battery connection, so I used that to go to Joerg’s M4 expander board. This fed 12.6v (3s) to the expander board, which has its own 5v reg which feeds power to the UART and M4 itself.

Here are a few pictures of all the wiring going to the PDBs. The only missing wires are the signal wires. I added them later on. Also, I used double-sided tape to mount the ESCs.

Other necessary wiring is from the PDB to the ADC port on the M4. I ended up using 2 3pin JST ZH series headers (455-1694-1-ND from DigiKey) for this. One for the ADC port and the other for Port 9 on the M4 for a Beeper. Normally, Port 9 is used for a Spektrum Satellite, but can be used for LEDs or a Beeper. I ended up need to use some shrink tubing on the connector because it seemed to bend too easily.

Once I have my ESCs wired up, I then put on some shrink tubing to be shrunken later on after I’ve done preliminary testing and I know things are good to go. I then put on my motors. I like to put the motors on and then cut the wires to length. Then I remove them, strip the wires to maybe 1 or 2mm and then tin them. Then I re-add the motors and solder them on. I found the KISS ESCs rather easy to solder even with their small size. I soldered a few other ESCs and they were harder to do because they required more heat to get going. Not so with these KISS ESCs.

Now we’re pretty much done. I hooked up power and fired things up. Motors armed, but they didn’t seem to do much when I applied some throttle. Of course I didn’t have props on when doing this. No magic smoke!

I tried a normal ESC calibration by having the M4 connected QGC and then adding the battery. With my sticks on full throttle I didn’t get the beeps I was expecting. Normally, at full throttle you’ll get initially beeps and then you move your sticks to no throttle and you’ll get a 2nd set of beeps to confirm end point calibration. So I decided to go with method B for calibrating the ESCs. With Menno’s firmware there is a function called MOT_ESC_CALI. If you set it to 1, it will calibrate your ESCs endpoints. The way it works is you set it to 1, then flash the M4, then exit QGC, unplug USB and then remove the battery. Then plug back in the battery and wait for series of beeps. Then remove battery again to save the settings and then replug in. Voila!

As a side note: At first I was restarting the M4 via QGC and the ESCs would calibrate, but after a few restarts and battery swaps the ESCs would lose their settings and I’d have to re-calibrate. I found that using the scheme above worked.

Now we’re ready to pop on the props and fly!

[Simson]

[Mullet]

Tuning! I find this to be the most difficult part to comprehend at this point in time because of lack of experience. With time, I’m sure I’ll have it figured out...

So on to my first flights and my first foray into Quatos tuning. The first flight was an utter failure. The quad might have gotten a foot off the ground, if that, and flipped and broke a prop or two. Back to the bench! It turns out I had a reversed prop. And I thought I had triple checked everything.

At this point, all settings are default other than my A1 and A2 and other associated settings coming from Quatos Tool. AM1 is -10 and AM2 is -25. L1K1 is 18.6. Prop K1 is 14.6 and QUAT_TAU is .05

I then proceeded to take the bird out for another fly. From what I could tell there were higher frequency vibrations and what looked like mid frequency vibrations. It wasn’t too wobbly to fly. Yaw was really sluggish though. The quad would do some weird things like flip over in mid air. Strangely, it would recover. Sorry no maiden video yet. I would be too embarrassed to post it. Moving along...

So I did some reading about Quatos tuning and it sort of made sense. I think I get the gist of what AM1 and AM2 do. AM1 is how much correction to apply to achieve a good rate. And AM2 is how much thrust to apply to achieve that rate. AM2 should be almost double AM1. Am I understanding this correctly? I’m not sure about L1K1 (overall gain factor), Prop K1 (prop torque), QUATOS_QUAT_TAU (manual response speed), and QUATOS_MAX_OUT.

So I looked for another similar sized quad to see what their settings might be. I ended up using Afernan’s settings for Q10-M4 Quatos-V2.txt located here:

viewtopic.php?f=40&t=3650&start=20

Using Afernan's settings, I set AM1 to -3 and AM2 to -4. L1K1 to 5. Prop K1 to 100. I also changed QUATOS_M_TLT_RT to 12 and QUATOS_M_YAW_RT to 6. QUATOS_MAX_OUT was lowered to .2 from 4. CTRL_FACT_THRO was raised to .8. Finally, I upped CTRL_MAN_YAW_RT to 180 to speed up yaw a bit. Ultimately, I figured since the quad was about the same size that it would fly at least semi-decent. After getting it into the air again, now the quad was very noticeably wobbly, but it wasn’t a slow wobble. As you guessed, this wasn’t the right tuning for this quad. Back to the drawing board.

So then I decided to move up a bit with my AM1 and AM2 settings. I settled on -8 AM1 and -11 AM2. And lowered my Prop_K1 to 85 from 100. I took her out for another flight and things seem to improve drastically. There is maybe a tinge of high frequency vibrations when coming out of a banked turn. It’s hard to tell. Also the quad seems to react quickly to throttle changes. We'll have to investigate what this means via some logs.

It looks like there are a good amount of vibrations going on. Not good, but the craft doesn’t seem to be impeded by this. However, I am noticing in the logs a lot of saturation but not on the top end of the range. This is hitting the floor. Still not sure what would cause this. So I figured I’d kill a few birds with one stone and change a few settings...

Here’s a pic of what looks to be the saturation...

Back on the bench, while staring at logs and scratching my head about the saturation, I finally figured out what throttle factor is. I looked at a log and determined that I was coming in at around 435. So I ran the formula 0.7 * 435 / 700 = 0.435. I settled on a slightly lower .425 for my CTRL_FACT_THRO. I also lowered AM1 to -6 and AM2 to -11. I also raised QUAT_TAU to .1 from .05. I left the rest of the settings alone.

Here's a pic of what I used to determine throttle factor...

It’s time to fly! Now we’re talking! Now I can get some decent flight without the throttle being so jittery. I’m not sure if I can get better tuning, but for now this seems like a good place. Saturation is also not as bad, but it’s still slightly bottoming out. What can be the cause of this? Also, I’m not sure if I’m noticing the effects of QUAT_TAU.

At this point, I’m kind of happy how the quad flies. Now it’s time to figure out how to get exactly what I’m looking for… the best settings for a racer style quad. The question is am I going in the right direction?

I have a few other things to work on like GPS functionality. Right now I’ll start with a 10mm patch antenna and most likely make a dipole because they seem to work well. I’m also going to reprogram my bluetooth radio to 57600 to play nicely with my OSD on the same TX channel.

Also included are my current parameters.

Current_BlackBird180_Params_092915.txt

(14.9 KiB) Downloaded 1533 times

That’s all for now… Hopefully, my trials and tribulations have helped and will continue to help others.

-Scott

PS I will try and upload something to YouTube... surprisingly have never done so.

[aBUGSworstnightmare]

[LPR]

Scott

If you want a well tuned quad the first thing to do is to start over by going back to defaults or Angel's setting.
Then, only change one setting at a time to see the response you get.
If you have an extra Tx channel and pot to use for adjusting the parameters you can adjust a parameter while flying.

I use two extra channels and pots to adjust Am1 and Am2 while flying.

I'm confused about your MOT_VALUE_SCAL 35000.

With Kiss ESCs I've seen some people use the maximum RPM of their motor and prop.

Other's have used a value that's equal to the maximum PWM that gives the maximum RPM for their motor and prop minus the PWM value that starts their motor. That value should be around 900.

This method seems correct to me because the M4 has no idea how fast your motor is turning if you're using Kiss ESCs but it does know the PWM value it's outputting.

Larry

[Mullet]

[LPR]

Scott

I've not used Kiss ESC with Quatos yet but I read somewhere in this forum that with Kiss ESCs you should use the difference between the PWM micro second that start a motor and the PWM value that gives the maximum RPM. Depending on the ESC's throttle calibration and when your motor reaches it's maximum RPM that value should over 500 and less then 1000us.

QUATOS_MAX_OUT limits the amount of tilt control and it should be set high and then lowered by looking at how the motor respond in the logs. I have not been able to understand exactly how to do that yet. I know if it's too low you can loose control and crash. I've done that a few times. Having it too high probably causes a little inefficiency's but not crashes.

For your small quad I would set QUATOS_MAX_OUT to 10 and after you have the other settings working well I would try to reduce QUATOS_MAX_OUT till it cause a control problem that you can see in the logs.

Using the Knob to set the Qautos parameters is a bit confusing. No value changes in the QGC. If you connect to an Android phone with bluetooth to the M4, in the AQ app you can see the parameters change when you turn the pot on the Tx.

The knob control is a little different then I expected. If your pot is centered the value you have for the parameter your trying to change, will not be changed. When you increase the pot's PWM value above center the parameter value will double when the PWM value is at 500us. When you decrease the PWM value by 500us the parameter value will go to "0".

QUATOS_M_TLT_RT is quite simple, it's the maximum rate of tilt in radians/second.
One radian is around 57 degrees. I would start with 1.5 and increase it if you can get your quad flying well. When your getting to the point of racing the quad you might want to go as high as 10.

Larry