Let's Make Robots!

How can i measure the thickness of ice

How can i measure the thickness of ice.

Is there an easy way either with IR or Laser to do this.

Why :-  It would be far safer to send a robotic car across an ice lake to test if the ice is thick enough for skating - or even in a rescue type operation.

Any answers however lateral and crazy welcome.......

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Cat and Dog and Fox tracks across the lake are the first signs that the lakes are ready for testing :-)

In response to the laser question - no. Lasers emit 'X'mW of power, but they don't care what happens to it. A second sensing apparatus would be needed to monitor the effect of the laser on the ice.

The major disadvantages with drilling that I immediately think of are:
• High power usage
• Slow operation
• Difficulty of getting good purchase on the ice - this bot isn't going to weigh as much as a person I'm assuming?

I was just thinking of using a 'tapping' mechanism when I read your post Rudolph =D
A small solenoid would 'punch' the ice, and a spring loaded piezo sensor (for good maintained contact with the ice) would listen for the reply echo. Since you know when the solenoid is firing you can make sure the piezo ignores the first 'tap'.

The first tap could trigger the timer.

Did you ever try throwing a stone onto a large field of lake ice. (well recommended)

The stone impact (non destructive) scatters sound in all sorts of directions like a stereo signal - its really an amazing sound.

and this stereo sound is different with different ice thickness - there maybe a way to trap and analize

Dutch ice masters test the thickness for a required minimum. Let's say 15 cm.

A drilling bot would not have to drill all the way through. Drilling 15 cm would suffice. If the hole stays dry after that, the ice is deemed safe to walk on.

Yes i did not think of this rational - "Pass" or "Fail"  thickness details are not really relevent (only safety).

Ekkkk we had only 13cm last year.

They make around 20 sample holes on the ice lake here and check each day for variation.

If you where to make a deep cone plug(in wood) to plug the hole after then it would be easy to remove and recheck .....hmmmm speculation again...

This is tough and therefor interesting.

IR or laser: light penetrating ice. Ice is very variable in its optical properties. The Dutch love their winter sports. Our mountains are not much to speak of. So skating is our winter sport. For as long as we will still have winters.

We tend to prefer "dark ice". That is actually clear ice. No air is trapped. No snow frozen onto it. It is hard, smooth, solid ice. I like to think it is stronger as well. But I am no "ice master".

Sometimes clear, dark ice captures bubbles rising from the bottom as it grows thicker. This gives a 3D impression of the thickness of the ice. To a human eye that is.

I really have no idea how an automated optical sensor would use all this info. I am just trying to find a hole in my "too difficult" comment.

How about ultra sound? My boat has an US "sounder" for measuring (sounding) the depth of the water. Of course, water conducts the ultra sound and the bottom reflects it. I wonder if the underside of an ice sheet would also reflect US. Your transducer would have to make good contact with the ice. Without freezing stuck to it. And so would the receiver.

A converted maxbotics US distance ranger might provide an interesting experiment.

Our Nederlandishe neighbour friend cringes at the state of our ice fields here...... yes bubbles and snow crusted.

 Our local lakes have inlet and outlet streams too - so the underlying water level is not so constant either.

I would guess that US would travel quite well through solid ice - meaning low accoustic signal (Hmmm !! no sure) - good job i have maxbotic in my pocket, though not sure how it would pick up secondary signals. maybe displaced RX and TX transducers would make easier option.

Using US would have the ability to find the "fish" shoals as well

I suspect IR will br problematic, as there will be many unexpected reflections coming from debris and chips in the ice, etc.

You could place a filtered photodiode on the underside of the robot, and in front of that attach a servo with a laser mounted to it. The laser starts off aiming straight down and rotates such that the laser traces a line backwards towards the photodiode. Provided the photodiode is far enough behind the laser, the reflection off the top surface of the ice won't hit the photodiode. When the laser has finished its sweep, you can examine the angle the laser servo was at when peak laser reflection was detected by the photodiode. Triangulation using the peak servo angle and the distance from the laser axis to the photodiode gives you the distance to the bottom of the ice.

Ultrasonic might also be an interesting one to try, although the speed of sound in ice will be extremely fast compared to the speed in air. You'd need to get something between the ultrasonic emitter/receiver and the ice to 'conduct' the sound through the surface of the ice, rather than just bouncing off it.

Whichever approach you use, you should put a little snow plough on the front of the robot =D
It's look sweet and help reduce the problem of debris interfering with your readings.