KK2 Ramping Up Throttle?

[Mustang7302]

Trying to sort through flight issues with my new Bat Bone build. The biggest issue I am trying to sort through is getting the pivot to re-center itself after direction left or right is given; it gets close but is still off enough to make the tricopter spin like a top when it takes flight. When testing the setup at low throttle, I have found on a few occasions as I give left or right yaw that suddenly the power to the motors ramp up quickly and I have to chop the throttle off. Even just trying to watch the rear motor for stability with the throttle at like 25%, several seconds later the power to the motors ramp up again to just about taking lift and I have to chop the throttle quickly.

A quick Google search didn't find much of anything on the topic as I describe it. Has anyone else experienced this?

• KK2 with v1.6 firmware (may have done it on v1.2 as well, but I was sorting through other issues to really take notice.)
• Tricopter motor layout
• PI Editor:
  Roll & Pitch:
  P Gain: 100
  P Limit: 100
  I Gain: 70
  I Limit: 70
  Yaw:
  P Gain: 70
  P Limit: 40
  I Gain: 40
  I Limit: 20
• Stick Scaling:
  Roll: 30
  Pitch: 30
  Yaw: 50
  Throttle: 90
• Misc. Settings:
  Min Thrott: 10
  Height Dampening: 0
  Height D. Limit: 30
  Servo Filter: 50
• Self Level Settings:
  P Gain: 35
  P Limit: 20
  ACC Trim Roll: 0
  ACC Trim Pitch: 0
• Mix Editor:
  Ch1: Stock
  Ch2: Stock
  Ch3: Stock
  Ch4: Rudder @ -100, Offset @ 55 (sets pivot level), Rate @ High
• ESC's were calibrated a couple of times.

Even when I reset to factory defaults, set the tricopter layout, set the auto level to aux, the power will slowly ramp up and then burst into power to provide lift and I am forces to chop the throttle quickly.

• RCTimer 750KV Motors
• RCTimer 20A SimonK ESCs
• 10x4.5" Props
• 4000mAh 4S Battery

I am willing to take any ideas I can get at this point.

 

[earthsciteach]

I've been having the same issue in regards to the spinning. I haven't noticed the power surge, though. Unfortunately, mine is out of operation until I get a new servo.

 

[vk2dxn]

Sounds like a sloppy servo not re centering if you know what I mean

 

[Mustang7302]

I've been having the same issue in regards to the spinning. I haven't noticed the power surge, though. Unfortunately, mine is out of operation until I get a new servo.

Yea, I saw the thread where it was discussed you had a stripped servo causing your top spinning issue. What does a stripped servo feel like? The servo I have on there seems to hold very firm to its orientation, just that is cannot return to center when the prop is spinning fast or slowly.

To be safe I ordered a new servo that has 50% more torque today which I am waiting to come in: Turnigy 380MG Micro Servo (Metal Gear) 3.6kg / .15sec / 15.6g . For reference the current servo I am using is the RCTimer Metal Gear Digital Servo. I hope the new servo will fix the centering issue; but doubt it will fix the self throttle ramping issue.

Sounds like a sloppy servo not re centering if you know what I mean

That is -a- issue, but I dont think it is causing the throttle to ramp up on its own while still sitting on the ground.

 

[earthsciteach]

The spinning issue is not due to the stripped servo. I had it do the same thing with a new servo installed today. If you are using a metal gear servo, it is unlikely that it is stripped. I've stripped 3 nylon gear servos on mine. If you have a stripped servo gear, you will be able to turn the servo arm without the servo motor turning.

Have you checked that the control rods are tight in the easy connects? Also, is the servo are clearing the landing gear?

 

[Mustang7302]

The spinning issue is not due to the stripped servo. I had it do the same thing with a new servo installed today. If you are using a metal gear servo, it is unlikely that it is stripped. I've stripped 3 nylon gear servos on mine. If you have a stripped servo gear, you will be able to turn the servo arm without the servo motor turning.

Have you checked that the control rods are tight in the easy connects? Also, is the servo are clearing the landing gear?

So you're having a centering issue too with the new servo that was installed today?

I figured I would be able to feel the servo not keeping its position when it is powered up and assumed it was stripped. Again my servo is very firmly holding position, just not finding center until you wiggle back and forth a couple of times.

I got rid of the control rods pretty early in sorting out the centering issue, just trying to remove any room for error. I was having slop between the servo and the motor mount, I found that part of the issue was the plate that the servo mounts to in the G10 mount was sliding around some. Some hot glue on that plate, along with remounting the servo in line with the pivot, took out all of the slop.

 

[Cyberdactyl]

I'm using a Blue Bird analog and the KK2 with 1.5. It too doesn't re-center perfectly. To me it's not a huge deal because it comes very close. I'm not having those other issues you mentioned.

One thing it does do is if I have the throttle ...just... where the props are spinning, the rpms will very slowly increase over about a minute or two where I have to touch the throttle or it will start to skid/float from becoming weightless.

 

[vk2dxn]

That is -a- issue, but I dont think it is causing the throttle to ramp up on its own while still sitting on the ground.[/QUOTE]

Sorry I missed the part about throttle ramping up. May be end points? I'm still to get my kk2 in the air to learn all the ins and outs of it.
Good luck

 

[aiidanwings]

If the front motors aren't level, it will throttle up as you describes. More so in the direction of the motor pointing outward.

Throttle stick scaling at 90, and yaw at 50 with a 4cell on a tri seems a bit aggressive to me. But I'm a pokey flyer.

 

[Mustang7302]

I'm using a Blue Bird analog and the KK2 with 1.5. It too doesn't re-center perfectly. To me it's not a huge deal because it comes very close. I'm not having those other issues you mentioned.

One thing it does do is if I have the throttle ...just... where the props are spinning, the rpms will very slowly increase over about a minute or two where I have to touch the throttle or it will start to skid/float from becoming weightless.

Yea, the servo is pretty far from center after input. What makes the KK2 ramp up throttle on its own?

If the front motors aren't level, it will throttle up as you describes. More so in the direction of the motor pointing outward.

Throttle stick scaling at 90, and yaw at 50 with a 4cell on a tri seems a bit aggressive to me. But I'm a pokey flyer.

The rig sits level in the middle of the room. Since it is indoors I try to keep the throttle down to prevent lift off but also have enough spinning for the rudder input to be acted upon. When it bursts the throttle, it trys to leap up and I have to chop the throttle for safety sake.

The setting are more or less stock. If changing something could help the centering issue or help the throttle creep issue, please make the suggestion!

 

[Cyberdactyl]

[edit] I had it backwards

I think the yaw not re-centering perfectly could be my tricopter's direct drive yaw. The female socket on the yaw mechanism (red below) is not centered with the axis of the servo axis (black). It's VERY close. . .maybe 0.5mm or slightly less from side to side and maybe 0.3mm up and down, adding up to an approximate 1mm swing. That probably adds a very slight binding force and stops before it can center perfectly. It's so slight, I don't feel the need to redo it. Since the servo is held by nylon ties, that error is forgiven somewhat by the servo being allowed to move slightly.

The offset error below is not to scale in the illustration in respect to the servo's post and socket. I highly exaggerated the error to show the movement as it turns from one side to the other.

 

[earthsciteach]

Mustang - what are your P and I limits set to? From what I understand, this sets the range that the motors and servos can move to an extent.

I just reset everything to factory settings, recalibrated the escs, and centered a new servo. It is flying MUCH better now.

 

[Mustang7302]

The limits are posted in the first post, teach. What servo did you end up getting?

 

[earthsciteach]

Plucked another TowerPro SG 90 out of a plane.

 

[earthsciteach]

Try resetting to factory settings. Under self-level, my P gain is set to 100 and P limit is 20. Maybe that will make a difference.

 

[Mustang7302]

Could you also post your PI Editor settings too, teach?

 

[earthsciteach]

Yup:
PI
Axis: Roll/Aileron
P Gain - 50
P limit - 100
I Gain - 25
I limit - 20

Axis: Pitch/Elevator
P Gain - 50
P limit - 100
I Gain - 25
I limit - 20

Axis: Yaw/Rudder
P Gain - 50
P limit - 20
I Gain - 50
I limit - 10

These are the default settings with V1.6.

 

[airhawk]

whatt batery are you using i had this problem too except it was inverted

 

[Mustang7302]

Yup:
PI
Axis: Roll/Aileron
P Gain - 50
P limit - 100
I Gain - 25
I limit - 20

Axis: Pitch/Elevator
P Gain - 50
P limit - 100
I Gain - 25
I limit - 20

Axis: Yaw/Rudder
P Gain - 50
P limit - 20
I Gain - 50
I limit - 10

These are the default settings with V1.6.

Thank you. I will give these a shot. Probably wont get very far with the servo not finding center; but we shall see.

whatt batery are you using i had this problem too except it was inverted

Turnigy 4000mAh 4S battery or Parkzone 1300mAh 3S. I am not sure which problem you're speaking too and how it was an exception by being inverted.

 

[Mustang7302]

DJFrank's "Tricopter" thread might have solved my issue. I will see when I get home.

Presently, when I get the motors just spinning and give it left rudder the tail leans left. In the air though, the tail leaning left will turn the tricopter to the right. So, the flight controller just might be trying to do its thing but its in air rudder corrections is actually exaggerating the issue. With the slop gone in the servo pivot now, the FCB just might be able to compensate for the servo not finding center very well.

I will plug in Teacher's settings in the PI editor and auto level editor, then I will change my rudder control back to +100 for the fourth channel in the mixer editor, and calibrate the ESCs one more time since the reset to defaults.

Too bad it is dark when I get home for the next couple of weeks, but I will still try it in the back yard. I just hope it doesn't try to make friends with my baby Japanese Pear tree again.