Mikrokopter Why does our MK/Droidworx Y6 yaw better clockwise than anticlockwise ?
- Thread starter ZAxis
- Start date
Bartman
Welcome to MultiRotorForums.com!!
andy
that's a strange one. the only uncommanded yawing i've seen has been related to low batteries. i've also read that there can be directional issues with the new style Navi boards.
If you're absolutely sure that the batteries are adequate and not over discharged when the yaw occurs, and that the wires to the power board are adequately large to prevent brown-outs at the FC, I'd say it might be a good idea to remove the Navi and GPS and see if the problem persists with just the FC in place.
Do all the motors turn freely? are the props all the same minus the CW/CCW variations?
It might be worth it to check the alignment of the motors again to make sure they're absolutely plumb and not leaning inward or out.
Good luck sorting it out
Bart
that's a strange one. the only uncommanded yawing i've seen has been related to low batteries. i've also read that there can be directional issues with the new style Navi boards.
If you're absolutely sure that the batteries are adequate and not over discharged when the yaw occurs, and that the wires to the power board are adequately large to prevent brown-outs at the FC, I'd say it might be a good idea to remove the Navi and GPS and see if the problem persists with just the FC in place.
Do all the motors turn freely? are the props all the same minus the CW/CCW variations?
It might be worth it to check the alignment of the motors again to make sure they're absolutely plumb and not leaning inward or out.
Good luck sorting it out
Bart
Droider
Drone Enthusiast
3am light bulb moment
You have a motor allocated incorrectly on your distribution ring
http://www.multirotorforums.com/showthread.php?649-Uncontrolled-Yaw-SOLVED
Dave
You have a motor allocated incorrectly on your distribution ring
http://www.multirotorforums.com/showthread.php?649-Uncontrolled-Yaw-SOLVED
Dave
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ZAxis
Member
Spent the evening checking motor assignments & alignments and prop directions. These all seem correct.
We're using 4s 3900mAh 20C batteries so I'm reasonably sure we have enough capacity. On a couple of flights, a power climb did induce yaw but the battery was nowhere near full capacity so low battery may exacerbate the problem.
I was wondering if the mixer table could be a source of trouble. I am using the motor order from a page linked from the Mikrokopter wiki
http://www.mikrokopter.de/ucwiki/mkm
Motor order is 1-2-3 on top 4-5-6 underneath. Dave has his as 1-3-5 on top 2-4-6 underneath and a different mixer table that has the same values as mine but rearranged according to equivalent position.
Can anyone explain how the values for the table are worked out ?
Four of the motors have their direction reversed by MKtools, the others are as default.
Too many variables .....
andy
We're using 4s 3900mAh 20C batteries so I'm reasonably sure we have enough capacity. On a couple of flights, a power climb did induce yaw but the battery was nowhere near full capacity so low battery may exacerbate the problem.
I was wondering if the mixer table could be a source of trouble. I am using the motor order from a page linked from the Mikrokopter wiki
http://www.mikrokopter.de/ucwiki/mkm
Motor order is 1-2-3 on top 4-5-6 underneath. Dave has his as 1-3-5 on top 2-4-6 underneath and a different mixer table that has the same values as mine but rearranged according to equivalent position.
Can anyone explain how the values for the table are worked out ?
Four of the motors have their direction reversed by MKtools, the others are as default.
Too many variables .....
andy
ZAxis
Member
Droider
Drone Enthusiast
Andy.. I sent you my mixer and motor allocations.. They work.
Did you use this mixer?
http://www.device.name/mk/Q4Y6V2.mkm
If not post up the link to the one u used... it does not sound like the battery at all I dont get ANY unpredicted Yaw at battery alarm voltages.
Since the one I had on saturday I have not had any other instances and as I said I got a Motor Restart warning when it happened to me. I take it with the MX20 you have telemetry
Dave
Did you use this mixer?
http://www.device.name/mk/Q4Y6V2.mkm
If not post up the link to the one u used... it does not sound like the battery at all I dont get ANY unpredicted Yaw at battery alarm voltages.
Since the one I had on saturday I have not had any other instances and as I said I got a Motor Restart warning when it happened to me. I take it with the MX20 you have telemetry
Dave
This can also be related to the props if they are flexible. As the hub warms up they can create different response. Although the FC will compensate in roll and pitch it cannot take much tolerance to differential torque changes. Props have to be identical all of the time. Try fitting left hand props that are slightly different to right hand ones and you will see what I mean.
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Jake Bullit
Fly,crash,glue,repeat!
Could it be a prop is slipping under load?
ZAxis
Member
We had an interesting evening with AirconRob trying to analyse the yaw problem. He's had many years in heli's and has a good eye for things.
The most significant discovery was that the problem manifested itself only when flying backwards to the takeoff point. It did not happen if you flew the MR forward straight away from you.
At some point on the return flight the yaw would occur. It would slew anticlockwise, say 90 deg. As it approached the takeoff point it would slew back to normal heading.
Rob's eye picked up that the motors are not aligned vertically very well at all. The tilt is probably contributing a yaw component in one direction that has to be compensated for by the flight controller, compromising control in one direction.
So job one is to get this sorted.
The Droidworx arms have alignment holes that have little adjustment. The motor mounts have alignment pips that should match the arm holes and guarantee vertical alignment. I'm not sure they do.
Looks like I'm going to have modify one or the other. Any tips on the best way ?
Life in interesting times continues ....
andy & lec
Many thanks to Rob for his time and advice
The most significant discovery was that the problem manifested itself only when flying backwards to the takeoff point. It did not happen if you flew the MR forward straight away from you.
At some point on the return flight the yaw would occur. It would slew anticlockwise, say 90 deg. As it approached the takeoff point it would slew back to normal heading.
Rob's eye picked up that the motors are not aligned vertically very well at all. The tilt is probably contributing a yaw component in one direction that has to be compensated for by the flight controller, compromising control in one direction.
So job one is to get this sorted.
The Droidworx arms have alignment holes that have little adjustment. The motor mounts have alignment pips that should match the arm holes and guarantee vertical alignment. I'm not sure they do.
Looks like I'm going to have modify one or the other. Any tips on the best way ?
Life in interesting times continues ....
andy & lec
Many thanks to Rob for his time and advice
Andy and Lec, It was good meeting you guys, As being self employed of my own business seeing and doing what i like when i like, when it comes to talking rotors, helping friends i find that time anytime. It's not a problem, I'm glad i have being of some help to you both. I'm 99% certain the issue you have is down to the motor angles. If that cures it we'll have a beer:tennis:.
Oh I nearly forgot, Andy, Ill call over sometime tomorrow with nazza and we'll have a fly.
Cheers
Rob
Oh I nearly forgot, Andy, Ill call over sometime tomorrow with nazza and we'll have a fly.
Cheers
Rob
Droider
Drone Enthusiast
I described the best was in a thread I think Plingboot started .. flat surface, sleet ruler, feeler gauges.. The play in the inboard retaining bolt should be enough to sort it.. slacken this and get the bottom blade tips parallel with a flat surface through as much of the 360 degrees as possible then rigtighten.. then start on the top one ensuring each bolt is tightened equally. make sure the gap between the motor mounting plates remains equidistant on both sides as you clamp them in position. keep checking the bottom blade tips.. slowly slowly until both top and bottom are as parallel to the surface as possible.. it takes time..
ZAxis
Member
Dave ... thanks for the tip
Another observation.... Reading through the flight log, the current and temperatures for motors 1, 2 & 6 were always low (< 20A,20deg) while those for motors 3, 4 & 5 were always high (>50A, 60 deg ).
Motors 1,2,6 turn clockwise, Motors 3,4,5 turn anti clockwise.
This implies there is a strong yaw that the FC is counteracting all the time .... another pointer to misaligned motors I reckon.
andy
Another observation.... Reading through the flight log, the current and temperatures for motors 1, 2 & 6 were always low (< 20A,20deg) while those for motors 3, 4 & 5 were always high (>50A, 60 deg ).
Motors 1,2,6 turn clockwise, Motors 3,4,5 turn anti clockwise.
This implies there is a strong yaw that the FC is counteracting all the time .... another pointer to misaligned motors I reckon.
andy
Bartman
Welcome to MultiRotorForums.com!!
Andy,
Glad you're making progress getting things sorted out.
I'mnot sure how you'd go about doing this with the droidworx motor mounts but I'm using a small scale stuck to the mounts to get them level. I have the scale tucked against the mount so it stays in place in perfect alignment with the mounting plate then I sight over the scale to get it aligned with the top of the top frame plate. I sight left and right to see if it's aligned on both sides then I tighten the mount and check it again before moving onto the next one. You'd have to rig your own method but it's fast and accurate plus I can do it in the field if I bang things up and have to do a quick rebuild. Nothing has to be level when I do it, I just need my scale and a couple of tools to loosen and tighten things.
Here's a pic for reference
View attachment 2971
Regards,
Bart
Glad you're making progress getting things sorted out.
I'mnot sure how you'd go about doing this with the droidworx motor mounts but I'm using a small scale stuck to the mounts to get them level. I have the scale tucked against the mount so it stays in place in perfect alignment with the mounting plate then I sight over the scale to get it aligned with the top of the top frame plate. I sight left and right to see if it's aligned on both sides then I tighten the mount and check it again before moving onto the next one. You'd have to rig your own method but it's fast and accurate plus I can do it in the field if I bang things up and have to do a quick rebuild. Nothing has to be level when I do it, I just need my scale and a couple of tools to loosen and tighten things.
Here's a pic for reference
View attachment 2971
Regards,
Bart
Attachments
ZAxis
Member
Spent a bit time truing up the motors. Did it with a combination of steel tape, vernier callipers, short steel rule and a small spirit level plus an iPod Touch running a bubble level app.
First got the frame level on a smooth surface, luckily the floor was actually level. Tackled one arm. Took the motors off so I could check if the motor brackets were level and see if there was any adjustment possible. They weren't and there was none. Slackened off the boom clamps and got a bit of adjustability. Using the small spirit level got the brackets as level as possible. Reassembled the motors and their mounts. Rechecked the motor mounting plates were level. Used Bart's method to eyeball it and confirmed by the spirit level. Then used the steel tape to check prop tips were the same height from the ground, top and bottom. Some slackening and tightening of the mount bolts got the top and bottom motors level. Repeated the slackening and leveling for the other two arms.
The iPod Touch wasn't used much but was perfect for setting up the gimbal.
So ready for another test flight, fingers crossed.
andy
First got the frame level on a smooth surface, luckily the floor was actually level. Tackled one arm. Took the motors off so I could check if the motor brackets were level and see if there was any adjustment possible. They weren't and there was none. Slackened off the boom clamps and got a bit of adjustability. Using the small spirit level got the brackets as level as possible. Reassembled the motors and their mounts. Rechecked the motor mounting plates were level. Used Bart's method to eyeball it and confirmed by the spirit level. Then used the steel tape to check prop tips were the same height from the ground, top and bottom. Some slackening and tightening of the mount bolts got the top and bottom motors level. Repeated the slackening and leveling for the other two arms.
The iPod Touch wasn't used much but was perfect for setting up the gimbal.
So ready for another test flight, fingers crossed.
andy
Jake Bullit
Fly,crash,glue,repeat!
I love a happy ending