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MIT Tailsitter Drone Acrobatics

aera.mit.edu

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Re: MIT Tailsitter Drone Acrobatics

#31

Post by abecedarius »

NortySpock wrote: post #12
xwdv wrote: post #4

Do these designs scale up? Don’t see why we haven’t created full sized aircraft with this form factor. Seems like it would make a great aerial weapons platform.

It's all fun and games until the engine or propeller goes out.... Mustard on YouTube did a video on the French SNECMA Coléoptère, which had a ring for a wing. It tended to rotate while hovering, and hard to steer during landing. (9 min) https://youtu.be/unz6mfjS4ws

Interesting, thanks. At the end (~6:50) there are a few seconds about the aerodynamics of the 'wing', which had been my first question.

Re: MIT Tailsitter Drone Acrobatics

#32

Post by dtgriscom »

fwlr wrote: post #7
njoubert wrote: post #6

Ah, tailsitters. Everyone loves the theory, then the practical realities of the takeoff position exposing the entire wing surface to the prevailing wind quickly kills real-world applications. I remember back during the 3D Robotics heyday watching Chris Anderson repeatedly run down to set his tailsitter upright, take a few steps back, only to watch it fall over again.

For vertical takeoff and landing the wing surface is mostly irrelevant, right? Seems like if you gave the rotors a “landing configuration” where they rotated 90 degrees you could lay the wing flat on the ground.

Movable motors would greatly increase the complexity and weight.

Re: MIT Tailsitter Drone Acrobatics

#33

Post by dtgriscom »

dmix wrote: post #3

I'm curious if it'd be harder for a soldier to spot a tailsitting drone high in the sky floating above doing surveillance. They are already impossible to spot as it is at certain heights. It would have to be right above them though.

Good point that a vertical wing is hard to see from below, but quad copters don't have wings, and so don't have that problem (the rest of the body has width, and is visible, but that's mostly the same with a tailsitter).

Re: MIT Tailsitter Drone Acrobatics

#34

Post by dtgriscom »

krisoft wrote: post #27
exDM69 wrote: post #20

Earlier quoted context omitted.

I certainly noticed the marker balls, but... On a quick glance, they do not mention if they are using the external cameras for the control algorithm or just verifying the results. The QR code-like markers on the gates suggests that there is also some onboard cameras. The statistics on the measurement errors suggests that they have a ground truth (from external cameras?) which they compare to some other source of meas…

> The QR code-like markers on the gates suggests that there is also some onboard cameras. I would be carefull with conclusions like that. These facilities are usually shared between a lot of different experiments through the years. The presence of QR codes on the gates certainly implies that someone at least once thought they might want to use onboard cameras in some experiment. Are they used in this project? You can…

I'm pretty sure that the "facility" is a gymnasium with cloth on the walls and floor to protect them. And, the hanging gates are rigid pink insulating foam sheets, probably made and hung custom for this project.

Re: MIT Tailsitter Drone Acrobatics

#36

Post by krisoft »

dtgriscom wrote: post #34
krisoft wrote: post #27

Earlier quoted context omitted.

> The QR code-like markers on the gates suggests that there is also some onboard cameras. I would be carefull with conclusions like that. These facilities are usually shared between a lot of different experiments through the years. The presence of QR codes on the gates certainly implies that someone at least once thought they might want to use onboard cameras in some experiment. Are they used in this project? You can…

I'm pretty sure that the "facility" is a gymnasium with cloth on the walls and floor to protect them. And, the hanging gates are rigid pink insulating foam sheets, probably made and hung custom for this project.

> I'm pretty sure that the "facility" is a gymnasium with cloth on the walls and floor to protect them.

Plus the tracking system. Which is the big differentiator of course. And the fact that it is not used for basketball games but to test indoor drones.

What else do you think you need for an indoor drone testing facility?

> And, the hanging gates are rigid pink insulating foam sheets

Yes.

> probably made and hung custom for this project.

No.

Here is an earlier MIT aeroastro project using the same gates from 2021: https://aeroastro.mit.edu/news-impact/system-trains-drones-t...

And this is the point I am making. There are many student studying aeroastro at MIT. Not all of their projects are about small drones but many are. And if the small drone test they want to do fits into this room they seem to prefer it. And if one project makes some gizmo (like those gates) for themselves and it looks usefull they won’t throw it away, but chuck it somewhere for storage and then the future projects, such as this one we are just discussing, reuses them.

Re: MIT Tailsitter Drone Acrobatics

#37

Post by fisian »

Flatness[1] based control is pretty neat.

Basically, you can define a trajectory (that is differentiable n-times) and then calculate the state of the system from that.

In this case, given the trajectory they could compute the speed, acceleration, jerk and yaw+rate for the tailsitter ahead of time using the model.

[1] https://en.wikipedia.org/wiki/Flatness_(systems_theory)

Re: MIT Tailsitter Drone Acrobatics

#38

Post by chabons »

neltnerb wrote: post #16
chabons wrote: post #2

Interesting research. Assuming that the benefit of fixed-wing aircraft is efficiency in relatively straight flight, I'm wondering how this aircraft compares in efficiency vs agility against a quadcopter of similar weight.

What would be your guess? I'm reading this as describing straight line wing flight for long distances rapidly shifting to erratic motions if someone doesn't like it existing. I imagine it's much more efficient at that, assuming that shell is mostly batteries anyway. Very neat to watch, I'd be curious to hear under what conditions it's worse than a quadcopter, perhaps stability or how quick it can turn.

We're thinking along the same lines, I guess I just expected the upsides and downsides of the approach to be quantified somewhere in the research as context for why it's meaningful.

Re: MIT Tailsitter Drone Acrobatics

#39

Post by dmix »

dtgriscom wrote: post #33
dmix wrote: post #3

I'm curious if it'd be harder for a soldier to spot a tailsitting drone high in the sky floating above doing surveillance. They are already impossible to spot as it is at certain heights. It would have to be right above them though.

Good point that a vertical wing is hard to see from below, but quad copters don't have wings, and so don't have that problem (the rest of the body has width, and is visible, but that's mostly the same with a tailsitter).

Yeah soldiers in Ukraine said that the Mavic drones are basically invisible to people on the ground. Unless they spend a lot of time looking for them.

It's probably not the biggest issue.

One thing is whether they can aim a grenade dropping drone easier or would the wind shift it even more.

Re: MIT Tailsitter Drone Acrobatics

#40

Post by Isamu »

fisian wrote: post #37

Flatness[1] based control is pretty neat. Basically, you can define a trajectory (that is differentiable n-times) and then calculate the state of the system from that. In this case, given the trajectory they could compute the speed, acceleration, jerk and yaw+rate for the tailsitter ahead of time using the model. [1] https://en.wikipedia.org/wiki/Flatness_(systems_theory)

>differential flatness

I am trying to understand this a bit better. Do you have other examples?

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