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Robot Bat With Echolocation
productdose.com writes "A robotic bat head that can emit and detect ultrasound in the band of frequencies used by the world's bats will give echolocation research a huge boost. Sonar in water is a mature field, but sonar in air is far less advanced. Whenever a robot team wants to build an autonomous robot they look at sonar first, but they quickly run into problems due to the simple nature of commercial sonar systems, and switch to vision or laser-ranging. The
IST project CIRCE hopes that the research they can now do with the robotic bat will lead to more sophisticated sonar systems being used for robot navigation and other applications."
BTW, that URL shows me using a pair of screen windows to "fend" one off (I was only armed with a frisbee) - I figured that would provide a pretty good radar return as "solid" surface.
Hulk SMASH Celiac Disease
Who says the visual spectrum of the EM band is the best way to interperit the world.
Wet, the only way to be sure if something is wet is to touch it (or put some other sensor into or onto it. I've seen lots of thengs that "looked" wet but it was just the glossy type look.
Soft, Sound is a MUCH better indicator for softness than sight. We've learnt that certain things look hard and soft. it's no measure if they are or not. You can make a barbell out of foam and with a good paint job it will look exactly like the real thing until you touch it. it won't however sound like a solid piece of metal. the returning sound will be muted / distorted.
Alive, see soft. I've seen people make realistic looking things on the beach. They could never have been alive, but they can look it.
Sorry bot the 3 examples you've used would have to be the worst 3. A more likely reason we have 2 eyes is we were origionally predators. We notice movement and distance well. It helps us hunt. As sight is effectivly passive (we don't have to shine light out of our eyes) it allows us to be more stealthy.
While bats use sonar, it's an active sensor. you have to keep making sound to use it. If more predatory animals used sonar to hunt, then more hunted animals would be able to detect it.
Back on topic however, If naval sonar is so advanced, why is atmospheric sonar so lacking ?
isn't it essentually a timing thing (sound travels faster in denser mediums like water than air). put a different emitter on and then adjust the timings.
Oh and if you're just sitting down, not moving etc can anyone see that you're drunk ?
sonar does, indeed, suck. and not in the fun way.
/anyways/ pretty much seal the deal.
why, you ask?
1) it's an active sensing modality (unless you've got a really bigass submarine with phased passive sonar arrays and a huge baseline, you're not going to get any range data out of the thing passively).
2) it's really damn tricky to process properly. sonar tends to fail in littoral waters because of multipath, echos, etc. in man made environments, the multipath + echo issues become really damn hard to solve without some good 3D models of the world around you (but if you can build those models, why bother with the sonar?)
3) signal to noise ratios are killer. this coupled with the innate difficulties in processing sonar
4) compared to other sensing modalities for non-aquatic environments, sonar just can't compete. if you have a single, calibrated camera and know its pose relative to the ground, you can calculate the exact position of any object on the ground. (more generally: if you know the pose of the camera relative to a known plane, you can precisely determine the position of any point on that plane up to what the camera's resolution will allow) if you have a stereo head, things get a lot more interesting (you can combine stereo imaging with structure from motion and get some highly accurate ranges).
that all said, if this research can solve those problems, i know i will gladly use their sonar / echolocation stuff (it can't be blinded by the sun, unlike ladars, although both will have major issues with rain).
You are right, receiving a signal is not enough. You need to receive the right signal and then process it in the right way. The question is where to process. Traditionally, simple receivers were used and sophisticated processing performed afterwards was then supposed to get all the information from their output. That never worked. What we learn from bats is that the processing has to start early on, i.e., what signal ("sonar ping") to use, how to spread its energy in the environment, where to point the ear in the environment and for which sounds from where to be sensitive. Remember that by virtue of the data processing lemma in information theory, you can only throw information away when processing sensor output. However, if you influence the process where information is created, you have control over what information comes into the system.
Producing an accurate 3d landscape representation is probably not the way to go either. If you design a robot, this is rarely what you want. A robot has to navigate around and to attain some goals, so it should extract from its sensors exactly the information that it needs to do that. 3d Map are unnecessary detours in most cases, because you still have to interprete the map then.
Someone please correct me if I'm wrong; but I believe that moths actually have a natural "radar detector" for sensing their predator's (bats) pings.
Yup, although it's a purely passive system. There's a fairly extensive overview of how moths detect bats' echolocation pulses. The behavior is kind of interesting... If the moth hears a weak sound (indicating the bat is far away), the moths will just turn around and fly away. If the sound is moderate, the moth will start looping around or stop flapping its wings and flutter down like a leaf. If the sound is really loud, indicating that the moth has a few milliseconds before it becomes bat food, the moth will suddenly fold its wings in and dive down as fast as it can.
One of my profs mentioned that if you make really high-pitched noises around moths, you can initiate the various evasive maneuvers. I can't remember how to make the noise... maybe something like rubbing aluminum foil together could do it.
There's also a similar page on the neuroethology of bat echolocation.
You yourself reveal that you need "eyes" to see, that is, you need 2 of them. Without mutiple eyes, you can't establish a range to anything.
And why exactly is this a problem? Are you saying that researchers couldn't successfully sync send and receive information?
As a fisherman, I can tell you that bats are amazing, they often chase my bug around as I false cast.
If you're interested in bats, I recommend you get a membership with Bats Conservation International http://www.batcon.org/ For only $30 you can be a member. And helping furry creatures is good for the soul.
Or more correctly Cillia.
A single (ignore the pair for direction for a moment) detector element is not going to get any accurate (3D) results, no matter how good the post processing.
Also the shape of the ear is minor in comparison to the "array" of information from the messages the individual hairs(cillia) send to the brain. Not saying they're wasting their time, just that it will likely be sub-optimal by design. Also I'd bet the hair pattern(layout) is more important than the over all shape too. But then IANAB* so what do I know.
(*I Am Not A Bat)
"and because in echolocation, the sending sensor is not the same as receving sensor, you really need 4 sensors total."
Rubbish, a bat can catch a moth ("meaningfull object") in flight ("3D model"). It can do this in total darkness using two sensors and an emitter, it's the same principle as a robot carrying it's own light source in the dark.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
Back on topic however, If naval sonar is so advanced, why is atmospheric sonar so lacking ? isn't it essentually a timing thing (sound travels faster in denser mediums like water than air). put a different emitter on and then adjust the timings.
Air and water have very different sonic properties. Air is highly compressible, water is less so. Sounds travel short distances in air compared to water... etc.
Sonar was developed because you can't see underwater. The military has invested huge sums refining it. Above ground we can see, so nobody's bothered researching air-based sonar to the same degree.
Seriously this reminds me of an apartment I almost rented years ago... it was an attic of a building; there was a guy living there who was moving out in a few weeks and I was about to hand over the money when I noticed a butterfly net near his futon .... Being a smartass I was like, "Hey, are you a lepidopterist?" He said no, no, that's for the bats. Huh? "Oh it's no big deal - they show up every once in a while. You just turn on the radio to confuse their sonar and catch them with this net." OK, then what do I do? The guy picks up a baseball bat... "You hit it a few times with this bat until it stops moving and then you can flush it down the toilet." I almost lost my lunch right there. I wound up renting a room on the first floor -- so I lived in the house but I never ventured up to the attic after that story. I think bats are really cool but I could not imagine having to catch them and kill them in my bedroom on a regular enough basis to keep a net next to my bed.
Don't forget about human echolocation
we had always wondered why our cats were going into the room and jumping about.
Hah. I imagine a flying rodent would be a cat's idea of great fun. Smells like a mouse, flits about like a small bird, add some catnip and it might just be too much to handle altogether.
"...always new atoms but always doing the same dance, remembering what the dance was yesterday." -Richard Feynman