road surface type sensor

[psubond]

Does anyone know of a sensor type (preferably compatible with Arduino or other mcu) that can detect the difference between a driveway, gravel, grass and snow?  I am drawing a blank and any nudge in the right direction would be appreciated.  Sensors for distance are easy, figuring out a sensor for road type is escaping me.  Thank you!

[AndyC_772]

Sounds like fun. Rallying?

[senso]

Camera and into the hole that is machine vision?

[psubond]

Trying to come up with a type of device to help prevent a visually impaired person from stepping off the driveway.

[CatalinaWOW]

I believe this function is largely what visually impaired folk do with their cane.  The feel and noise of tapping gives them feedback on the surface.  You might try automating this process by generating taps in a short cane and evaluating the shock in the stick and the noise generated.   Whether this would be a benefit to a given person is unclear.  Perhaps to those who are also hearing impaired or with reduced tactile sensitivity.

You do realize that the world will cause you to fail in certain situations.  When it snows, for example, there is no difference between the driveway and any other surface.  They are all snow.

[nctnico]

Some machine vision (with color) should be able to do it. I don't think much processing power is needed because you can take snapshots and resolution probably doesn't need to be high. From there an algorithm which can detect granularity (outline detection + voronoi) combined with color should be able to give a clue on what kind of surface is under the camera. Probably a change in surface type can already serve as a warning.

[Gyro]

I suspect that a stick is likely to be hard to beat for reliability and positional accuracy.

It's possible that something like measuring ultrasonic reflectivity using a transducer might yield some useful / interesting results (maybe see through snow to the underlying surface too.

The other problem is form-factor, how does the person aim it accurately enough (and avoid damage to its sensor if it is hand-held). Again problems that an ordinary stick or cane handles rather well.

Some further clarification of the requirements would be helpful.

[psubond]

the gist of the potential project is a device for a  friend's son who is visually impaired.  He wanted to build a device that can detect when he is near the edge of the driveway when heading down to the bus (he is not blind and they don't just turn him loose to walk towards traffic alone, this is a supplementary project to assist him with staying on the paved surface).  Preferably I would make something that could detect surface composition, but that isn't as simple as obstacle avoidance.   I was also thinking maybe a setup like an invisible fence that could be made to buzz or vibrate in his hand when he is near the edge of the driveway.  Another option that I was considering was a gps receiver, but I am not sure if something like a NEO7m or NEO8m would have the positional accuracy.