proximity sensor accuracy?

[Rickz2020]

Hey all,

I will need to at some stage buy some proximity sensors for my robot and I am wondering how sensitive they are.
What will trigger them? Steam? How about a wave of water? A fly flying past?

Thanks,

Rich.

[mattallen37]

It all depends on the sensor(s). What specifically did you have in mind?

[Rickz2020]

What do you recommend? I want it to move away from solid objects but not things like waves or steam, but it must move if it detects glass or some other transparent material.

[mattallen37]

What range do you need? How precise does it need to be? How much of a field does it need to detect?

If it needs to detect glass without fail, I suggest ultrasonic. I don't know if IR will be able to detect glass properly (you might need a direct hit).

[Rickz2020]

Range about 1 or 2 meters.

Precision? Umm, not sure I guess 180degrees vision.

Would ultrasonic sensors detect waves of water? I'm hoping not.

[mattallen37]

If you need a range of 1-2 meters, and a field of vision 180 degrees, I think you will need more than just a single sensor. You will need either multiple sensors, or a motor to scan the sensor back and forth. Ultrasonic sensors will "see" water nearly as well as any hard surface (assuming the angles are right). IR sensors might not see it as well, but their range usually isn't very outstanding.

What do you need it for?

[Rickz2020]

I'm building a robot for water and if I decide I want it moving on the surface, then I will need to have a sensor that doesn't activate when faced with a wave - but does activate if something comes in front of it, like me in the pool.

Any recommendations?

[TechnoX]

Combine it with a heat sensor (TPA81)? It can detect humans but not the water
Or do you have other stuff in the water? Bolls and toys?

[Rickz2020]

Ya, there will be other stuff in the water

What about sonar?

[Flynn]

I'm really not a pro at this, but as I believe, an ultrasonic sensor is either the same or very very similar to sonar. They both rely on bouncing sound.

Maybe a solution would be to have it try to go through all objects it detects, it detects, and if it finds that it is not moving forwards, it knows the object is solid, other wise, continue to plow through it. It's a little blind, but if you aren't worried about your robot running into things, you could make it work with some sort of motion sensor.