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Having trouble with Tricopter gyro

#1
Over the weekend I decided it would be a good idea to build a tricopter from scratch with the spare Power Pack A motors I have laying around. So far I have completed the build and all the motors work, my DIY servo mechanism works well and the servo direction is correct. The board is mounted 90 degrees off which I have accounted for.

I'm using my reject Naze 32 rev 5 board. My rev 6 is in my quad. Both are running cleanflight.

I tested tricopter out and immediately observed that the yaw compensation is not moving correctly. If the model is rotated right by hand on the desk the yaw motor will tilt to the left instead of the the right. This reaction instead of stopping the rotation and keeping the model aligned in the air causes it to spin faster.

I tried to reverse the gyro, but the only command I came across in the CLI that I thought may help was yaw_control_direction = 1, I set it to -1 and all it does is reverse the servo.

I came across someone else who was using a CC3D and manage to fix a similar problem by reversing the gyro. Does anyone else know how to reverse the gyro for Naze 32 boards on Cleanflight?

The graphic shown on the setup page does rotate in the correct direction however.

I will continue to work on it but if anyone has a suggestion or solution.

Tricopter.PNG

UPDATE WORKED IT OUT, it was as simple as I thought.

Well I feel like a bit of an idiot now.
Anyway after 3 or so hours of trying to figure this out I found a direction and rate setting on the servos tab. I previously tried using this to change the direction the FIRST TIME but for what ever reason the servos are listed from 0-7 on the servo tab. I jumped over the the motor tab to make sure the servos were getting imput from my controller and the movements from rotating the quad by hand. On the motor tab the servos are listed to 1-8 so I was changing settings on servo 6 on the servo tab when I really should have been messing around with servo 5.

Anyway I will leave this here for anyone else with a similar problem. Short story, you don't need to reverse the gyro, the direction and rate tab in the last column on the servo page allows you to reverse the imput from the board to the servo so the motor tilts in the correct direction to counter any undesirable movement.

Now I know how to display the settings in CLI so I guess it wasn't all a loss
just write 'set' to see the current settings and 'set' along with the command to change a setting in that list.

Any tips on programming PIDs for a maiden of a custom build?

If anyone else has any DIY tricopters they would like to share.
 
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Habakkukk

Fly Eagles, Fly!
#2
There's a ton of pid tuning info for tricopters to be found on rcexplorer.se
I know it takes a lot more farting around for tricopters... Good luck!
 
#3
Thank you for the tip.

I got home from work and just plugged it in to check to settings, I set the orientation on yaw to -90 and gave it the PIDs from the naze 32 rev 6 setup video for the versa copter as a baseline.

First flight it wanted to yaw to the right constantly so I put some trim on it. Brought it inside and increased the deflection for the servo to -100%. Still yaws to the right a bit but its manageable with only 3 clicks of trim instead of 8 or so. The P gains were a bit high causing oscillations so I dropped all the P's by 1 each (too be expected I was using the versa copter settings). Just waiting on a battery to check out the new settings but it seems to be working pretty well. Way more responsive than I thought it would be, it hovers around 35% throttle haven't punched it yet but its got some power.

I was able to do a few circuits and went for another when it dropped out of the air onto my driveway, woops forgot to grab a battery alarm. Anyway this spare part tricopter using the old rev 5 board and a 5 gram servo from one of my old planes works great (the frame is some square length of wood I cut in a T pattern with two cross arms to make it stronger and to add mounting area.

I'm still a noob, but that is why I built it to fly the mini multirotor in the front yard when I don't have time to go down to the park and it looks like it is going to fulfill its purpose so I'm happy.

Update
Well I took it out again for a quick test and found that it wanted to spin on concrete. I assumed this was because the motors were not at full speed. Once I was in the air It was fine but the P's were still a bit high and the yaw motor was moving a lot introducing a fair amount of vibration.

Since the first flight I dropped the yaw P from 11 down to 9 to get the servo to stop over correcting. I then increased the servos travel on min from 45 to 55 degrees and left the max at 45 degrees so on takeoff the board has a little more to work with in order to counter the yaw spin as the motors reach there full speed or the speed required to hold a hover. Hopefully this does not introduce any bad tendencies, if so I will just change it back which may be the case later on once I am comfortable punching it up off the ground.

I also dropped the rate at which the servo will move to counter any unwanted movement from -100% down to -85% to see if it will smooth out the flight for hovering. In forward flight this is not a problem but while hovering the back motor tries to over compensate and slowing it down as well as dropping the P on yaw may help remove that tendency. I will have to watch it carefully tomorrow.

I am happy I took on this project as it is providing me an opportunity to learn how to PID tune a multi-rotor that is completely custom. I did have to change my versa-copters PID's but all I had to do was drop the P's by one and it flies great.
 
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#5
What sort of multi-rotors do you have? If you have any at the moment.

I'm not a complete noob to the hobby, generally a noob on flying multi-rotors though. I have been flying fixed wing since this time last year. Haven't really progressed passed S patterns on multi-rotors yet but I can manage flying towards myself and do some O patterns at a moderate speed. If you have any tips or advice for flying multi-rotors I wouldn't mind hearing them.
 

Habakkukk

Fly Eagles, Fly!
#6
What sort of multi-rotors do you have? If you have any at the moment.

I'm not a complete noob to the hobby, generally a noob on flying multi-rotors though. I have been flying fixed wing since this time last year. Haven't really progressed passed S patterns on multi-rotors yet but I can manage flying towards myself and do some O patterns at a moderate speed. If you have any tips or advice for flying multi-rotors I wouldn't mind hearing them.
I have quite a few miniquads, I build tune and sell them on occasion (just for fun) and I have a couple tricopters (2 mini tricopters from rc explorer) Flying these things line of sight is pretty difficult, in fact for the majority of builds you will never come close to reaching a miniqads full potential flying line of sight. If you can do laps line of sight and you understand how the things fly, than fpv will be second nature. The downside is that getting a good fpv set up is a science all its own and can be a little intimidating/expensive at first. I've tried dozens of setups and the most expensive isn't always the best. Also, stuff in the multirotor hobby breaks... A lot... It's just part of it. My advice for someone wanting to get into the hobby is to buy the cheapest most durable setup you can find and fly the snot out of it. When it breaks beyond a reasonable repair level than salvage what you can and move to a better setup.
 
#7
Hi again,

Went down to the park this time very easy to fly, and quiet! Switched it into acro this time, had one crash by no broken props. (At least quiet compared to my friend's father who was flying a 300 class helicopter).

I was talking to him as I flew the tricopter. He was surprised to see me flying in circles and doing some nice turns using the roll and yaw controls something he only just started doing with his helicopter after 4 or so years of having it. Of course you would be a lot more worried about making a mistake with something like that, especially when just replacing the rotors costs around $300 Australian.

People do keep their distance from your flight line when you put up one of those. Multi-rotors even if you setup when no one is there people will walk right where you are flying because they are quieter and less menacing.

The P's seem to be getting better, when I drop down from up high and throttle up there is a bit of vibration induced. I think if I drop the roll and pitch by 1 more it should do it. The wind likes to carry it a bit so I need to up the 'I' and there are a wobbles after imputing a roll or pitch quickly but only slight. I will have to edit the 'D' a little.

That is the correct procedure to resolving those problems right? I am pretty sure my diagnosis is correct but if you have any advice on doing that I would love to hear it.

I have heard only good things about David's tricopters are they as crash resistant as they are made out to be?
 
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jipp

Senior Member
#8
congrats, from the crash videos iv seen of davids tris yes they are pretty darn tough. does he use the same tail servo tilt system like FT sells. if so that thing seems bullet proof.. just need a strong metal servo to help keep the thing bullet proof.. i think its probably the weakest link in a tri?

yeah its amazing how these quads/tris attract new people.. which is good and also explains why this part of the hobby is growing so fast and lots of new people to the hobby which is good.

new blood is always good.. im a noob too.. the quad got me into this hobby.. i have a plane on order now and building a FT mini arrow wing on the dining table as i type.. maybe tomorrow ill feel up to cutting it out.

anyhow, congrats man.. you did good. i know if it was not for this forum i sure would not have a quad.. (well now i would as they have came down in price compared to a year ago ( about minis 5 months because of health but was thinking about it while in the hospital in my bed etc.. next time im taking a micro quad in to fly while in my hospital bed.. iv learn i can fly the blade nano qx with a small string so when it goes down i pulled it to me :D i have a bad leg etc ).. when there were no ready to fly mini quads under 600.00 ) times sure have changed.
im dumb as a box of rocks.. and with the forum iv been able build a quad.
FPV im slowly collecting parts for that. advice i was given.. do not go cheap on the camera. use a good filter, and antenna and you will have good results.


not flown a tri yet but i will build one.. considering building one for a action camera AP machine.. my original logic was to save money 3 of everything instead of six.. but after you buy a damn good metal servo for a 600mm size tri.. are you really saving much money.. shrugs.
but yeah i will build one soon. but yeah quads are bring people into the hobby and if there like me will start exploring other aspects of flight like gliders, planes etc.. i know im interested in every thing that flys. :)
rock on
ok man the pain meds kicking in gonna try to get some sleep.. good luck on your next flight.. this stuff is fun even if we crash from time to time.. i guess the one thing we should make sure we have.. lots of props.. if you aint breaking props you are not flying enough as they pros say :D
chris.

p.s

forgive my response.. hard time to focus to edit to make it some what readable.. i go to bed now.. good night.
 
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Habakkukk

Fly Eagles, Fly!
#9
The mini tricopter is pretty resilient, that being said I've had to rebuild mine 3 times so far, but I fly pretty aggressively. Also Swanno, I'm not familiar with cc3d open pilot, is there an option to set tpa and tpa breakpoints? If so, try setting your tpa to 20 and your tpa break point to 1600 to smooth out your pids at high throttle. (So if throttle mid point is 1500, when you throttle past 1600 your pids will scale back by up to 25% on your way to max throttle. So at 1700 your pids scale back by 10%, 1800 15% ect)
 
#10
I will have a look into the endpoints and throttle control.

Really have an itch to try some FPV though. I have been trying to build a wing using a hotwire but I messed up and don't have enough material to finish it. I have another thread called Versa wing airfoil or something along those lines but its been going pretty slow.

Generally I like to mix it up, fly fixed wing on the Weekends and Multirotors during the week or whatever I feel like I guess.

Pretty pleased with how the tricopter is going though, thank you for the suggestions.

Jipp, I hope you feel well and good luck on the flying, thank you for the nice comments. This forum is a great resource for help, information and a great place for talking with other people who are genuinely interested in RC or flight in general.

Thank you for all the help Habakkukk your advice helped me get it in the air!

If you were wondering about the Tricopter I never really went into specs.

3 Power Pack A motors I think they are 1806 2300 kv?
12 amp BL heli escs, not one shot capable.
1 5 gram nylon servo, seems to be doing pretty well and I have crashed a few times without it becoming an issue so far.
A Naze 32 rev 5 board series A I think without the diode so the motors get power from the usb cable. A little annoying but that is why It wasn't being used in my Versa Copter.
The Naze 32 is running clean flight.
The frame is made from some pine I got from the local Bunnings, a hardware store in Australia.
I painted it black so It looked better.
the circle mounts holding the motors are from the V1 Versacopter with some inventive mounting as the 3mm hex nuts were to big for the motors so I used the center of servo arms to offset them.
The tilt mechanism is a barrel bolt lock which I cut up and modified. The servo is attached using some linkage stoppers and a piece of piano wire.
The whole build comes in under 250 grams without the battery and I fly on I think it was a 25 C 850 mah pack which gives me a good 5-6 minutes flight time.
I am also using some 5x3 Dal props which I originally got for the mini plane series.
 
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