Variable pitch quadcopter using rasperry pi and navio+ question

Hi

I’m planning on constructing a variable pitch operated quadcopter with one helicopter motor distributing power through series of timing belt transmissions.

One of my concerns is that can I use rasperry pi and navio+ to operate motor esc and 4 servos?
ESC will run in governor mode in constant RPM.

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I was thinking about such a design as the “ultimate” drone, so good to see somebody trying to get such a thing working. I was inspired by the Tilt drone and Avatar film, with independent servos for each arm. With linear servos (screw-thread style) maybe the arms attach directly onto them.

One issue you will have to consider is servo update speed, similar to another question posted here the other day. As you plan to leave your ESCs pretty much constant that should not be a problem with lower update speeds, or maybe you can find good digital servos supporting fast updates. No analog servos then.

To help you with some inspiration check this out (just fun, it’s not real): https://www.youtube.com/watch?v=SNPJMk2fgJU

On the serious side that mock-up drone with “thrust vectoring” (not just variable pitch) is really more like one of the Avatar ships. In this case we would also need to tilt the motors side to side. That’s not possible with current/basic servos I think. It would need either a very large drone or better some kind of custom made on-arm gimbal.

The software to control such drones is going to be complex when used to full potential, so you can take advantage of the Navio/RasPi2 here. For example, imagine an FPV race where the rotors can tilt in opposing directions to air-brake on one side and power-through on the other, effectively going around a corner flat like the drone is on rails!

Hopefully you intend to keep it open source so we can all share and build on top of great ideas. It would be good to get frames like tilt, variable pitch and maybe later full thrust vectoring supported in APM and other autopilots. The guy who created Tilt said (in one of his announcement videos) he had great difficulty to customize one of the other autopilots (think it was CleanFlight or BaseFlight). To save time I’d check that out first for any tips.

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I suggest you do some investigation on helifreak. There is a few people using ardupilot on gassers. Although this is not your end goal. The primary issue will be the same. Dealing with the vibration related issues. It’s very possible, but requires some thought when it comes to your build. Let me know how it turns out!

Hey, although a very long lasting wait for my answer I will continue this.

Thank you for you responds. But I feel I started this so that you didn’t fully understand my end goal.

Short story, I am building a quad rotor (440mm sized rotors), which use one central motor and distributes that power over belt driven transmission to 4 arms. Arms have, for now what I’ve planned - to have 550 size heli tail rotor grips and collective pitch via servo.

The craft would be controlled with raspberry pi - navio flight controller, and here I think is the problem. I don’'t think Navio has a ready setup for to control 1 motor and 4 servos as quadcopter, what only comes to close is a single motor craft which is still different. I’m counting on that I could use that code to convert it for my purpose - but I don’t know code of any kind. I’d wish to see Emlid make a mode for collective pitch quadcopter model - I think it will be more efficient and popular in the end game market in the future.

What I have now is a prototype plan for the power distribution, some 3d printed parts: as head of the arm which envelopes bearings, axial and radial, pulley, shaft, rotor grips, collective arm and 3d printed propeller blades (these blades are exceptional and and very unique,overall diameter with grips is 440mm).

I have also Raspberry pi3, lte connectivity, personal design usb controls transmitter (plan to make it wireless).

What is next: (next 2-4 months)

A physical prototype of arms and transmission, after that; some more parts: Motor, batteries, more 3d printed parts, ESC, finalizing my usb controller.

After that; Tests…

I hope till now I have a plan how to use Navio…I really want to use it for my project.

I 3d modeling my self, and I have access to water jet cutting which makes this much more easier, and ofcourse 3d printing.

My thoughts are in, will Navio be my flight controller? Will it support my goals?

  • I really hope I can make best of navio!

As addition I could share my drive folder for pictures and more to come alongside with this project, will be updating.
Pictures

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You should just go full heli if you want collective pitch. I wont get into details but do some research on the efficiency as determined by the solidity of disk between single and multi rotors as well as efficiency differences between fixed and variable pitch at hover and forward flight. Once you see what is what why would you want to trade all the mechanic simplicity gains for a less efficient platform? Multirotors work for most in a narrow performance range because the mechanical simplicity gains outweigh efficiency deficits compared to mechanically complex but more efficient single rotors.

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Hi Joonas,

I looked through your google drive folder, really impressive work! Have you had any luck with the Navio controller? I’m currently building a collective pitch quadrotor as well and have been modifying ArduCopter code to control my servos, but haven’t gotten too deep into the code yet. I’d love to chat about this if you’re still pursuing the project!

Hi Trent!

I’m glad to hear from you.I am definitely going forward with this project. At the moment I am more or less collecting or producing components and refining cad models and trying to simulate flaws.

I still have two main problems, the code and establishing secure connection over lte. As I am not a software engineer or any of the sort I have not yet found the way to modify the code for my purpose. I would be really interested to chat about that.