Hi guys. :mrgreen:
So a few days ago, I was trying to think up a really crazy design for a robot and then one popped into my head - so, I’ve got the motion and stuff planned out but I had a quick question to ask … but first, some info on the robot.
The general idea is (and I have no idea if this is even possible) to have a hexapod robot with the front and back two legs implemented with some kind of helicopter rotors so that the robot can transform into a quadracopter. So the robot would lift it’s legs over it’s head until the feet were totally in-line (horizontally) with the body plates of the robot. The feet will be holding the stepper motor and rotor, etc. and here is where my question comes in …
Even if this isn’t likely to work - I was wondering if someone could possibly tell me an equation(s) for calculating thurst/lift generated by the rotors of an RC helicopter?
First of all… quality idea. And one I believe IS possible.
Obviously you’d really need to think about design and material.
Also some very strong servos to counter act the rotor torque. Although you could allow for the legs to lock into the body so the servos can power down, to save … well power.
As for working out torque/trust/weight etc then im sure there is a calculator somewhere in google.
A very interesting project that I know will catch the attention of DiaLFonZo.
If you want the legs to double as the rotor supports, the rotors will get in the way when walking, and the servo motors will be pushed to their limits trying to keep the “arm” straight in flight, consuming a lot of current.
It might be easier to connect a lightweight 12DoF hexapod or 8/12 DoF Quad beneath a lightweight quadcopter and share the battery. The arms on the quad might be able to pivot using a worm gear system to take up less space while the robot is walking, and the quadruped’s legs can lay flat against the quad’s arms while in flight.
Many of the brushless motors used for airplanes specify a maximum thrust based on a specific prop. These are often used on quad copters.
Hi guys - I quickly drew up this idea for a propeller. Is wondering if it would work?
It’s essentially a normal propeller but in and “enclosed” casing, so to speak.
The holes for the casings would be slightly larger than the motor shaft so they could be pinned down somewhere, leaving the propeller to spin.
P.S. Things I forgot to say in my last post. :mrgreen:
@Innerbreed: I saw that cat-copter a while ago in the Metro newspaper.
That is one “unique” idea that I would not like to try out.
@DiaLFonZo: Thanks for the link - I gave it ago and I’m sure it’s my inability to use it correctly but for some reason, I always get the same “Not enough power message”. I’ll give it another go later. :mrgreen:
@Zenta: Thanks for the video - that’s given me and idea. ^___^
@CBenson: Thanks for the link - the photos on the site where very helpful in answering some questions I had. :mrgreen:
I have think a lot of time to make a desigh with protected prop.
The first problem is choosing motor, since you can’t do such a design without knowing all the dimensions…
Ok, I think this design for the propeller should work. :mrgreen:
In this design, the rotor blades are free to move in the air without any obstructions and using the original idea for the containers, two layers can be created. The base layer can stay constant and if the motor needs to be replaced with one of a different size, then the top layer is the only thing that needs to be changed.
Hi, AK,
I have not built anything like this since I made a Ground Effect Machine out of a pie pan, a glow plug engine, and a Frisbee back in 1970, so I don’t know what I am talking about. That has never stopped me before.
If I wanted to quickly learn about modelling protected or shrouded propeller machines, I would check out how the RC aircraft people are currently building ducted fan models. They may give you ideas on how to shape the walls of the duct/shroud to increase thrust with the Bernoulli effect and to swivel the duct to vector the thrust (think Harrier). And they may have suitable motors and methods of mounting that would solve Eric’s concern about motor/prop swapping. These might be building blocks towards a hexapod-quadcopter.
One other thought: write a script or specification about what functions the hybrid will perform, what real world needs it should fill, and what problems it should solve. Not to criticize - I liked the MadLab video, and they proved they could do it - but their video didn’t show any requirement for walking ability when it could always reposition itself by flying.
Thanks for the info RoboTed, I shall check it out. :mrgreen:
…Although I must admit, the Roomba and Desk Fan idea is rather tempting.
P.S. To be honest, the protected propeller idea was more for aesthetics than anything else so if it’s more effort than it’s worth, I’ll jsut go for something simple. Main objective is to get a quadracopter working and flying about with the hexapod attached. After that, I can work on walking and adding sensors, etc. ^___^
Hi guys. I have another quick question …
Now, from what I’ve seen, on single rotor helicopters, the rotors themselves are rotated via those rotating unit thingies (sorry, I can’t really describe them - featurepics.com/FI/Thumb300/20070304/Helicopter-Rotor-Mechanism-240127.jpg) so by tilting the rotors forwards/backwards/left/right you can get the helicopter to move in those directions?
Am I right in assuming that a quadracopter can work on the same tilting principle? Or does it move by varying the speeds of the motors - i.e. if the quadracopter wanted to fly forwards, the back two motors would have a greater speed that the front two so it would fly forwards?
This is all probably totally wrong but that’s just the idea I have at the moment. :mrgreen:
AKdaBAOUS
P.S. An updated design idea for the quadracopter using the newly design rotor sections. :mrgreen:
The normal (and easiest) way is to change speed on each of the 4 motors according to the direction you want.
For that you have to put Clockwise and CunterClockwise prop
Varying the motor direction could be acheave but will add a lot of parts and weight.
There is various project that didn’t quite ended into full working copter that were using Variable prop (like a helicopter tail blade for exemple) instead of actual motor speed variation.
Again it take lot more parts…
Yes I agree. Using a “swash plate” design will make it a lot more heavier.
Using the props as directed by eric will be the best way to solve this. Infact the only way really. Enless you have total experiance with copters of this type.
Might also be a good idea to spend a bit of money on the R&D and buy a kids (or adult) quadcopter so you can understand how it works… as its not just a set of rotors making thrust. Its control is important and learning how it works is key.
So your not now mounting the props directly to the leg as first proposed, but rather adding a copter to the top of a hex. This would be easier, but not quite as exciting as your first idea.
