[stefe]

Hi, 

I am building a BB-8 from Star Wars and I would like to try to use a CC3D that I have in hand to add stability to the sphere.  I will be using a weight that I can move from left to right with a servo to tilt the body and a speed controller and motor to do the PAN (Forward/Backward) motion.

Is it possible to setup LibrePilot to do that ?

Thanks !

Stefe

[TheOtherCliff]

The ESCs would need to be reversible, preferably with full power reverse.

Add stability?  Does it remain upright when powered off?  In that case stability is mainly a matter of not increasing speed too quickly.  It should be possible to control without a CC3D, but a CC3D would make it easier to control.  Set CC3D up for say 90 degree max bank angle in Attitude mode, and when you slam the stick all the way forward the board and weight goes to 90 degrees for maximum acceleration, rather than spinning around and around like it would with full power but no CC3D.

If it must be actively balanced like a Segway, that is another matter.  I don't see why it wouldn't work with reversible ESCs from some minimum angle and properly tuned PIDs, but it would be a challenge instead of simple.

[stefe]

The ESCs would need to be reversible, preferably with full power reverse.

Add stability?  Does it remain upright when powered off?  In that case stability is mainly a matter of not increasing speed too quickly.  It should be possible to control without a CC3D, but a CC3D would make it easier to control.  Set CC3D up for say 90 degree max bank angle in Attitude mode, and when you slam the stick all the way forward the board and weight goes to 90 degrees for maximum acceleration, rather than spinning around and around like it would with full power but no CC3D.

If it must be actively balanced like a Segway, that is another matter.  I don't see why it wouldn't work with reversible ESCs from some minimum angle and properly tuned PIDs, but it would be a challenge instead of simple.

Thanks for your answer !

Yes the ESC is reversible and receiving command ike a servo motor so 0 deg is backward, 90 is at stop and 180 full forward with all the range.  Since this is a ball with a weight in the bottom this help for stability but active stability would help a lot more when doing side motion, forward and reverse. 

I added acceleration to help stability but I need a little bit more to make it perfect. 

Not really needed to be as balanced as a Segway since the weight is more on the bottom than higher and by itself it will not roll on the side more than 2-3 degres, but when doing head movement then the active stabilisation would help alot to keep it upright and steady.

I never programmed a CC3D what configuration would you use for this setup ?

Thanks !

Stefe

[TheOtherCliff]

Assuming that you know or will read up on how to configure a quad...

A problem with this design is that there is no yaw.

It probably will oscillate and you will need to reduce the PIDs.  Cut all PIDs in half to stop the oscillation.  Cut in half again if that is not enough.

quad +
attitude mode (Stabilized 1)
mount the FC right side up with arrow forward.
just use 2 of the normal 4 quadcopter motor outputs (you do have left-right as well as forward-reverse?)
front and rear quad motors are reverse direction of one another so pick the one that has the correct direction for you.
correct direction will move the weight forward when you push the stick forward.
correct direction will make it level and incorrect direction will flip upside down at full power.
same for left and right quad motors.  they are also reverse direction of one another

Holding ball to keep it from rolling.  when you give forward stick, it should move the weight forward.  Left should move it left.
set the max bank angle to 90 degrees (or less if the design requires less) instead of 55 (Stabilization -> Basic -> SettingsBank1 -> Attitude).

Arm normally and then immediately move throttle to the middle activate it.  It will move when you first arm it and it will move when you move the throttle, but if the PIDs are tuned reasonably, it should stop quickly.

For extra credit, you could redo the mix table to remove throttle/thrust and leave just the stabilization.  There is a mix type designed for reversing motors with neutral in the middle.  I haven't used it.

[hawkview]

Decat did this but me
This was done about 4 years ago.
Decat made a segway with a cc3d

[stefe]

Assuming that you know or will read up on how to configure a quad...

A problem with this design is that there is no yaw.

It probably will oscillate and you will need to reduce the PIDs.  Cut all PIDs in half to stop the oscillation.  Cut in half again if that is not enough.

quad +
attitude mode (Stabilized 1)
mount the FC right side up with arrow forward.
just use 2 of the normal 4 quadcopter motor outputs (you do have left-right as well as forward-reverse?)
front and rear quad motors are reverse direction of one another so pick the one that has the correct direction for you.
correct direction will move the weight forward when you push the stick forward.
correct direction will make it level and incorrect direction will flip upside down at full power.
same for left and right quad motors.  they are also reverse direction of one another

Holding ball to keep it from rolling.  when you give forward stick, it should move the weight forward.  Left should move it left.
set the max bank angle to 90 degrees (or less if the design requires less) instead of 55 (Stabilization -> Basic -> SettingsBank1 -> Attitude).

Arm normally and then immediately move throttle to the middle activate it.  It will move when you first arm it and it will move when you move the throttle, but if the PIDs are tuned reasonably, it should stop quickly.

For extra credit, you could redo the mix table to remove throttle/thrust and leave just the stabilization.  There is a mix type designed for reversing motors with neutral in the middle.  I haven't used it.

Thanks for the info I will start from that and work my way thrue it.  I let you know of the progress.

Stef