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MIT Tailsitter Drone Acrobatics

aera.mit.edu

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Re: MIT Tailsitter Drone Acrobatics

#21

Post by walrus01 »

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.

There are commercially available tailsitter UAVs primarily used for mapping purposes:

https://www.atmosuav.com/product/mapping-drone-marlyn?view=w...

It transitions into forward wing flight after take off. It does achieve a greater flight distance/flight time per battery compared to the same size of thing as a quadcopter, but NOT as great of endurance as something like a 2 meter wingspan VTOL with four lift motors + single thrust motor, such as:

https://www.foxtechfpv.com/foxtech-loong-2160-vtol-mapping-p...

Re: MIT Tailsitter Drone Acrobatics

#22

Post by fireant »

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.

There could be price savings too, right? Two motors less and simpler ESC gotta save something.

Re: MIT Tailsitter Drone Acrobatics

#24

Post by jojobas »

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.

Probably nowhere near this performance. Their motors instantly vary thrust by a factor of ten or more, this just can't be done at human scale.

Re: MIT Tailsitter Drone Acrobatics

#25

Post by someweirdperson »

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.

Does visibility matter?

I imagine a drone hunter flight of multiple drones, multiple drones implies multiple receivers, multilaterating the transmissions of the target, and splash.

Only works on surveillence drones that need to be transmitting, and don't emit only in the direction of the intended receiver.

Re: MIT Tailsitter Drone Acrobatics

#26

Post by krisoft »

rikeanimer wrote: post #17

Did no one notice the balls? Those are there so a set of external cameras [think motion capture] can feed in an absolute, essentially perfect state estimate to the control algorithm. It's probably a run of the mill system from Vicon [company]. Essentially if you're running vicon you can make flying things do things like you could make them do programming them in Blender or similar, subject to the [pretty minimal to t…

> Essentially if you're running vicon you can make flying things do things like you could make them do programming them in Blender or similar

It is not quite that easy though. Yes having an external tracker will give you a reliable, high quality source of position and orientation.

But that does not mean that you can “program them in Blender”. You still need to figure out what kind of trajectories your system can or can’t follow and how to map from position and orientation errors to actuation outputs.

If you can’t control the robot with external tracking then you have no hope of controlling it with internal state estimation, so if you already have the test facilities it makes sense to start with that. That way you are not debuging two crappy subsystems depending on each other and failing spectacularly.

Re: MIT Tailsitter Drone Acrobatics

#27

Post by krisoft »

exDM69 wrote: post #20
rikeanimer wrote: post #17

Did no one notice the balls? Those are there so a set of external cameras [think motion capture] can feed in an absolute, essentially perfect state estimate to the control algorithm. It's probably a run of the mill system from Vicon [company]. Essentially if you're running vicon you can make flying things do things like you could make them do programming them in Blender or similar, subject to the [pretty minimal to t…

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’t really tell by just looking at the presence of the QR code.

Same as I can’t tell if you are hungry or not by observing the presence of an oven in your kitchen.

Re: MIT Tailsitter Drone Acrobatics

#28

Post by swores »

walrus01 wrote: post #21
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.

There are commercially available tailsitter UAVs primarily used for mapping purposes: https://www.atmosuav.com/product/mapping-drone-marlyn?view=w... It transitions into forward wing flight after take off. It does achieve a greater flight distance/flight time per battery compared to the same size of thing as a quadcopter, but NOT as great of endurance as something like a 2 meter wingspan VTOL with four lift motors +…

I (as someone without a need for any drone and therefore without having looked at enough prices of drones to have any gut instinct here) was curious how much that first one you linked - the Marlyn UAV - might cost, since the company only says to contact them for pricing.

This page [1] suggests $17k, is that likely on the money (pun intended, sorry) or just a random scam site?

[1] https://volatusdrones.com/products/atmos-marlyn

Re: MIT Tailsitter Drone Acrobatics

#29

Post by tromp »

jojobas wrote: post #23
tromp wrote: post #19

Seeing it fly side-ways in circles (2 minutes into the 1st of the final 3 videos) is pretty wild. Not sure how the 2 rotors can create sideways thrust...

A slight tilt in the direction of flight?

Surprisingly it's going the same speed of 8m/s as the previous forward flight...

Re: MIT Tailsitter Drone Acrobatics

#30

Post by dtgriscom »

rikeanimer wrote: post #17

Did no one notice the balls? Those are there so a set of external cameras [think motion capture] can feed in an absolute, essentially perfect state estimate to the control algorithm. It's probably a run of the mill system from Vicon [company]. Essentially if you're running vicon you can make flying things do things like you could make them do programming them in Blender or similar, subject to the [pretty minimal to t…

Model airplane servos aren't "way slower" than brushless motors (with their propellers). Here's a higher-end servo that moves 60° in 68ms:

https://www.horizonhobby.com/product/a7090-brushless-low-pro...

I doubt a motor-prop pair could significantly change its speed in 68ms.

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