Randy Sonnicksen
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  • Belle Plaine, MN
  • United States
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Randy Sonnicksen commented on Alexandre Mainardi (Nuvem UAV)'s blog post An underactuated propeller for attitude control in micro air vehicles
"This is ingenious!  Very, very cool."
Jun 12
Randy Sonnicksen posted a blog post

Bearingless Rotor - Update

Test VideoI was finally able to perform a test of the new drive test stand.  The previous test stand used a 4-stroke engine and a less rigid test frame.  This test stand consists of a 6.5 HP, 2-stroke DuraForce engine coupled to a…See More
Jun 12
Randy Sonnicksen commented on Josip Nunth's blog post Boeing cargo Drone Prototype. Does this make sense?
"Josip, Yes, my assumptions were that if you just scaled the model up using same materials. I think you are right that carbon, especially carbon with a light filler material changes the equation dramatically. The variable pitch quad I am working on…"
Apr 8
Randy Sonnicksen commented on Josip Nunth's blog post Boeing cargo Drone Prototype. Does this make sense?
"I wondered the same thing.  Here are my thoughts.. Multicopter Scalability"
Apr 4
Randy Sonnicksen commented on Randy Sonnicksen's blog post Servo Redundancy
"So I was thinking... If I use a triple redundant system, it would be feasible to allow one of the 3 controllers to implement integral control. The potential side effects could be: This controllers servo's would do more work.  With proper…"
Mar 29
Randy Sonnicksen commented on Randy Sonnicksen's blog post Servo Redundancy
"Chris, Yes, if the broken servo free-wheels, I'm SOL.   Regarding pitch control range, I'm planning to only use the middle 2/3 of the servo's range during normal operation so that extra range on the servo is available to…"
Mar 21
Chris Card commented on Randy Sonnicksen's blog post Servo Redundancy
"Interesting project. Regarding the coupling of the servos as depicted in the image (top of page)... What happens if one of the three servos breaks in way that allows it to "free-wheel" , no resistance ? If a servo fails and is immobilized…"
Mar 21
Randy Sonnicksen commented on Randy Sonnicksen's blog post Servo Redundancy
"I posted a comment on Axel Borg's (AmazingDIYProjects) youtube video wondering how he handled integral control with 5 independent controllers, and....HE ANSWERED!  Which is very uncharacteristic for him.  He indicated that the flight…"
Mar 16
Armin Strobel commented on Randy Sonnicksen's blog post Servo Redundancy
"I just would make sure that you limit the maximum servo position of every servo. I also agree the integral parts could run in different direction, but if you make sure that you have some kind of anti windup for your integrator in a range where it…"
Mar 15
Randy Sonnicksen commented on Randy Sonnicksen's blog post Servo Redundancy
"Armin, Yes this is a bit tricky.  I was wrong before thinking that PID on the roll/pitch rate control would avoid divergence between controllers.  This will be a problem if I use integral control. I wonder how the guy in Amazing DIY…"
Mar 15
Armin Strobel commented on Randy Sonnicksen's blog post Servo Redundancy
"I was assuming that it would be a cascaded PID. Straight roll/pitch I highly would doubt that it would work reliable, if at all. The integral part might be actually a port of the solution. In normal operation it might could happen that one integral…"
Mar 14
Randy Sonnicksen commented on Randy Sonnicksen's blog post Servo Redundancy
"Armin, The algorithm I'm playing with has a roll/pitch angle proportional controller cascaded to a roll/pitch rate PID controller. If I'm thinking correctly, the separate controllers shouldn't "wind up" their integral term,…"
Mar 14
Armin Strobel commented on Randy Sonnicksen's blog post Servo Redundancy
"I understand. Also additional complexity may not reduce the risk if not done very carefully. I agree. Your system needs to be tuned towards robustness that it can handle safely one servo / flight controller failure. You are also right you really…"
Mar 14
Randy Sonnicksen commented on Randy Sonnicksen's blog post Servo Redundancy
"Armin, I hear what you are saying, and....this project has already gotten more complex than I had originally hoped. So, my approach at this point is to let the healthy systems compensate for the unhealthy ones.  I acknowledge that during a…"
Mar 14
Armin Strobel commented on Randy Sonnicksen's blog post Servo Redundancy
"Nice project! I would consider some feedback from the servos that you know which one failed that the other ones can compensate for the lost travel. You may want to consider a module in front of every servo which is connected to all PWM inputs and to…"
Mar 14
Randy Sonnicksen posted a blog post

Servo Redundancy

I continue to develop my "full scale" gas powered, variable pitch quad-copter.After watching the video below at Amazing DIY ProjectsI realized (more vividly) how vulnerable a quad is to any fault in the control…See More
Mar 14

Profile Information

About Me:
Mechanical Engineer. Always interested in flight and the engineering challenges.
Please tell us a bit about your UAV interest
Full scale UAV with aspirations to make it an MAV
Quadcopter configuration.
2.4 meter rotor diameter.
36 HP with 175 Kg gross wt.
Testing single rotor performance, various blade, hub, drive configurations.
Hometown:
BELLE PLAINE

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Randy Sonnicksen's Blog

Bearingless Rotor - Update

Posted on June 12, 2018 at 8:48am 0 Comments

Test Video

I was finally able to perform a test of the new drive test stand.  The previous test stand used a 4-stroke engine and a less rigid test frame.  This test stand consists of a 6.5 HP,…

Continue

Servo Redundancy

Posted on March 14, 2018 at 7:12am 11 Comments

I continue to develop my "full scale" gas powered, variable pitch quad-copter.

After watching the video below at 

Amazing DIY Projects

I realized (more vividly) how vulnerable…

Continue

Bearingless Rotor for Variable Pitch Quadrotor

Posted on March 28, 2017 at 8:12am 3 Comments

This video shows the fabrication of a prototype bearingless rotor hub/blade design.

The rotor diameter is 93 cm (36.6 in) and will operate at 1,410 rpm generating 2,000 g's of acceleration at the rotor tip, and developing 1,600 Lbs of tension in the flexelem rod due to centrifugal force.  The blade…

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Multi-Rotor Scalability

Posted on April 22, 2016 at 3:41pm 23 Comments

This is an analysis of the variables which affect the ability to control a multi-rotor as the size is scaled up.

This will show why at some point, variable pitch must be introduced.

I hope to follow this with another article which includes Phase Margin and Gain Margin, but right…

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