A swarm of micro-quadcopters • Hacker News Board

Re: A swarm of micro-quadcopters

#41

Post by jpk » Mon, Feb 06, 2012, 8:21 AM UTC

jakevoytko wrote: post #10

gbrindisi wrote: post #6

Earlier quoted context omitted.

Using a gyroscope, gps, accelerometer and some other sensors is not a difficult step to perform.

It's pretty hard. This assumes the existing radio links can handle the extra bandwidth. I don't see a WiFi card, so they may use radios with low-baud serial connections. Maybe the radios are good enough that doubling the radio communications is fine. Now, all the new hardware means extra draw (and potentially extra batteries) on each quadrotor. They might fly with this extra weight, but it won't be nearly as long. Al…

> Also, indoor flying means no GPS.

Correct. However, indoor positioning tech will likely come of age in the next 12-18 months driven by indoor mapping and navigation. Once that becomes commoditized, it'll make positioning a little aircraft like this in the x,y plane of a floorplan doable without dead-reckoning. From there, you could probably do some crude lidar to measure the distances above/below the craft to the ceiling/floor.

Re: A swarm of micro-quadcopters

#42

Post by eik3_de » Mon, Feb 06, 2012, 10:59 AM UTC

cs702 wrote: post #35

The same video was posted a while ago: http://news.ycombinator.com/item?id=3542542

and before: http://news.ycombinator.com/item?id=3541996

Re: A swarm of micro-quadcopters

#43

Post by regularfry » Mon, Feb 06, 2012, 11:41 AM UTC

_djo_ wrote: post #30

regularfry wrote: post #23

Earlier quoted context omitted.

They're closer in concept (and presumably in deployment scale) to mobile CCTV cameras than they are to police helicopters, and there certainly have been privacy issues with those.

I'm not so sure. With the latest electro-optical turrets a helicopter can be pretty far away and still get usable footage. During the Football World Cup I observed some police helicopters orbiting just about out of earshot during their operations. I've also seen a demonstration of an experimental locally-produced surveillance camera (in this case intended for maritime observation) that was able to display the name on…

There's a huge difference in price, though. The numbers will probably work out that you can throw up a hundred or so drones for the price of a single helicopter. With a single expensive platform, expensive optics and highly trained operators make sense.

Re: A swarm of micro-quadcopters

#44

Post by theon144 » Mon, Feb 06, 2012, 6:31 PM UTC

yoos wrote: post #37

baddox wrote: post #8

Earlier quoted context omitted.

I completely disagree. None of those sensors would likely give anywhere near the accuracy, frame rate, or context of the current system. Also, there is the issue of where the computation is done. It seems obvious to me that the intended goal is a decentralized system, where every vehicle is autonomous and creates an internal model of its own surroundings. As best I can tell, in the current system all the computation…

Personally, I've operated accelerometers and gyros at 200 Hz after some low-pass filtering, which is really all you need for this application. I'm sure there are sensors that operate at even higher frequencies if need be. The GPS module doesn't have to be updated too fast (maybe 10 Hz?) because it only serves to correct for horizontal drift. I run the 100 Hz flight control loop for my tricopter on an ATmega1280 clock…

Even in best case scenario, I'm not sure GPS would be accurate enough, as it's only accurate down to few centimeters, you'd probably need more if you'd like to perform that kind of acrobatics as shown in the video. And what about the height? You could of course use GPS, but apparently (http://users.erols.com/dlwilson/gpsvert.htm), average consumer devices have error of few meters. Maybe we could use laser range finders pointed at the ground, but what if the quadcopter tilts? Or what if another quadcopter flies underneath it? Of course it's not unsolvable, but it'd probably require more computing power in the quadcopter.

What do you think?

Re: A swarm of micro-quadcopters

#45

Post by baddox » Mon, Feb 06, 2012, 8:09 PM UTC

theon144 wrote: post #44

yoos wrote: post #37

Earlier quoted context omitted.

Personally, I've operated accelerometers and gyros at 200 Hz after some low-pass filtering, which is really all you need for this application. I'm sure there are sensors that operate at even higher frequencies if need be. The GPS module doesn't have to be updated too fast (maybe 10 Hz?) because it only serves to correct for horizontal drift. I run the 100 Hz flight control loop for my tricopter on an ATmega1280 clock…

Even in best case scenario, I'm not sure GPS would be accurate enough, as it's only accurate down to few centimeters, you'd probably need more if you'd like to perform that kind of acrobatics as shown in the video. And what about the height? You could of course use GPS, but apparently ( http://users.erols.com/dlwilson/gpsvert.htm ), average consumer devices have error of few meters . Maybe we could use laser range fi…

I think LIDAR is the most likely solution. With enough resolution, you could get a reasonable 3D map of the vehicle's surroundings with a very accurate relative model of where the vehicle is located.