Touch Sensor

[The Mad Professor]

A device which may pave the way for robotic hands that can replicate the human sense of touch has been unveiled.

https://news.bbc.co.uk/1/hi/sci/tech/5056434.stm

 

[dknguyen]

Wonderful...

Tactile touch 1 for 1. Human hands still beat out in temperature sensing and "wetness". Actually, that's really weird now that I think about it, how on earth do human hands know its wet? Is it a high-level interpretation of tactile sensing?. Still not quite there yet...

 

[tech-freak-wanabe]

i think a human can tell if something is weat trough temperature change. have you ever touched something and thought it was wet and it actualy isn't

 

[dknguyen]

No

i think a human can tell if something is weat trough temperature change. have you ever touched something and thought it was wet and it actualy isn't

No. I don't think so. That's weird.

 

[Daniel James]

i think a human can tell if something is weat trough temperature change. have you ever touched something and thought it was wet and it actualy isn't

That is an interesting point you make. When I get the clothes off the line on a cold morning at first I can not tell if they are cold or damp. so temperature could have something to do with it.

also I think the brain could compare the texture of the surface of an object to what it should be and decide it is wet.

 

[Hero999]

The are probably both cold and damp.

 

[philba]

That is an interesting point you make. When I get the clothes off the line on a cold morning at first I can not tell if they are cold or damp. so temperature could have something to do with it.

also I think the brain could compare the texture of the surface of an object to what it should be and decide it is wet.

put on really thin latex gloves and hold your hand under water, it still feels wet to me. however, it's not just temperature because it feels wet under hot water too.

 

[Daniel James]

It would depend on how acurate you needed to be also. I remember reading about tiny robots that needed to detect a spill. I think the water acted as a conductor to complete a circuit on the bottom of the robot. wetness detected.

if the robot had a memory it could reference the object or surface it is touching. then detect a change of friction on surface, a change of temperature (hot or cold), a change in the way light bounces off the surface, a change of weight(often something wet weighs more). maybe detect unsual movement (a dribble). I'd find it interesting to see if using all these variables a robot could be programmed to detect if something is wet or not. I'd imagine we'd be getting quite complicated here.

I've had a search on the web and found little on robots sensing wetness so far.

I would be interested to see if anybody else new of any efficient ways for a robot to sense water.

 

[StopGo]

put on really thin latex gloves and hold your hand under water, it still feels wet to me. however, it's not just temperature because it feels wet under hot water too.

I think your eyes are also telling your brain if something is wet, and this is merged with the tactile sensation from your fingers. A proper test I think should involve a blindfold to remove the visual stimulus.

After all taste double blind tests show some really odd things, like people not being able to tell orange juice from lemonade etc.. people get fooled by what their eyes see all too easily.

 

[dknguyen]

Maybe it's the temperature differential. There are few things where the temperature can change so suddenly so quickly and encompass the hand (as opposed to just touching a cold piece of metal).

It's probably all of them- temperature, temperature differential, texture, and fluid currents.

 

[philba]

I think your eyes are also telling your brain if something is wet, and this is merged with the tactile sensation from your fingers. A proper test I think should involve a blindfold to remove the visual stimulus.

After all taste double blind tests show some really odd things, like people not being able to tell orange juice from lemonade etc.. people get fooled by what their eyes see all too easily.

yes, that's true (double blind needed) but I knew my hands should have been dry so i don't think its an issue of expectation. In fact, I thought there was a leak in the gloves at first (they were quite dry when I pulled the gloves off). even after I knew (that I would feel that sensation and not be wet), it was still a very realistic experience to me. I think it may have something to do with the way a fluid stimulates the skin.

by the way, I am not sure how you could construct a double blind experiement here. both the administrator and the subject shouldn't know if the hand was really placed in water. seems like it might be hard to arrange - water has a unique viscosity.

 

[phalanx]

Cognitive psychology which deals with the mental processes of our behaviour (including perception) is a fascinating subject.

It is amazing how much data our brain actually processes at any given time. Most of the subtle sensory queues from our environment are not consciously recognized by us but are instead accumulated and processed as a whole and presented as a general "feeling." Wetness is only one of the many things we can detect without much difficulty even though it is extremely difficult to quantify how the brain actually interprets it. Body language and auditory queues in spoken language are also included in this field.

If you have the time and are interested in how the brain processes data, this is a great topic to read up on. It is also highly related to artificial intelligence research.

 

[Blueteeth]

Hi,

I think we do feel 'wetness' by temperature change, after all, water is a pretty good conductor of heat when compared to say...wood. And sometimes the equipment I work with feels 'wet', but it isn't, its simply because its metal thats been stored in a car over night, so its cold.

I heard something interesting on the radio last week about feel and taste. They mentioned some research group produced 'evidence' that senses generally work together, for example, 'flavour' is a combination of taste, touch (in the mouth) and sound and vision. Ever dyed a food blue and got someone to taste it? they usually hate it, no matter what it is.

How on earth the brain processes this information I don't know, but it might as well be different for everyone, we're all different. And each 'sense' measures many different things, I mean, 'touch' for example:

temperature
pressure
difference in pressure (is something solid? or does it move)
and difference in 'feel' between parts of the body, like in the finger, for 'texture'.

I also read in New Scientist a while back (can't remember) that the human eye can detect a single photon. However, because that is not very useful, and the brain would be bombarded by such information, the brain filters out these signals, and only registers 'light' when there are roughly 10 or more photons. That made me wonder what else our brains filter out. If our senses are much more 'sensitive' to real world information, and the brain ignores most of it what, then surely we could find a way to not filter.

As to how a 'robot' would use sensors, I think the key is combining them. use all the inputs it has available to measure something, and then store this information for latter reference.

my two cents (ps, I'm really just an electronics guy)

Blueteeth

 

[philba]

I'm no expert but I believe the sensation is based on multiple inputs to your brain. Just temperature isn't sufficient. go outside on a cold day without a coat - you don't feel wet. Wetness also changes the friction coefficient and pliability of our skin, probably changes the response of tactile receptors and so on. I suspect that there are many subtile effects - each alone doesn't signal wet but enough of them cause the brain to think "wet".

I bet that cold metal has condensation on it so it may well be wet, perhaps slightly so but still wet.

 

[Hero999]

That's true you can still tell the difference between dry cold metal and wet cold metal. You can even tell the difference between liquids which leads be to the conclusion it's texture that tells us the difference.

 

[Sig239]

I remember an experiment my chemistry teacher did in school where she filled an aquarium with water then sprinkled some kind of powder on the surface. When I submerged my hand in it, it sure felt wet, but when I took my hand out it was dry. I believe it was a lesson in surface tension. When my hand was submerged, the powder remained between my hand and the water, not one drop of water made it through, and no powder left on my hands. Has any one else done this?

 

[akg]

ohh...(if there were)poor fishes

 

[Sig239]

LOL No fish..... Just a tank of water....uuhhh and the powder of course...uhhh Oh yeah and all the dirt and grime off of thirty school aged kids hands!!! Yum

 

[Hero999]

The powder forms a protective layer around your skin, but you can still feel the liquid through it, just like you would if you were waring a plastic glove.