HudzonHawk

I've been working on a little project and stumbled on a slight problem that requires movement detection.

Here's a simplified model of the problem:
Suppose we have an object that is moving at a *very* high speed through a flat surface. As it moves, it will pass through a point "P". The moment it reaches P, the movement detection gadget must detect the object and give out a beep.

Two things to consider:
1) The surface should remain flat(preferably).
2) Since the object will continue to move, the time it'll remain in contact with P will be *very* short: t < 0.1s or even t < 0.01s

Can anyone suggest a solution of how I can detect the movement of the object? Or at least point me in the right direction?

Nigel Goodwin

In electronics terms your time intervals aren't particularly short, but your requirements are too vague to comment on. Try telling us EXACTLY what you are trying to do, that way we might have a chance?.

__________________
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HudzonHawk

Not short? Hmm..That's a relief. Was afraid it might be moving too fast...

Anyway, the project I'm making is on acceleration. A steel ball (diameter = 1 inch) will be accelerated to a high speed and sent rolling through a surface.
The movement detector is required to identify the exact time when the ball reaches point P and then send a signal to my computer saying "The ball has touched point P at time T".
It would also be nice if that movement detector could measure just how fast the velocity of the ball is.

I hope this isn't too vague. I'm not too good with explaining minor details as you can see. If it still is, please feel free to ask questions about specific parts of the project.

Nigel Goodwin

I still don't really understand what you're trying to do?, is this for a class project or something real?.

Basically to measure the speed you need two signals, which the object triggers sequentially - a pair of light beams is a common method. You simply measure the time between the breaking of the two beams.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

HudzonHawk

Bah! Don't tell me I'm that bad in English. -_-;;;
English is my third language, with algebra being first and Russian coming close as second. So don't blame me if I'm that bad.

This isn't a class project (I wish we had that kind of stuff in class...). I'm fiddling with a new method of acceleration I've thought up. While eventually I want to see if I can design an engine that'll work with this kind of acceleration, right now I want to test just how well it works. And I'm doing so by accelerating a steel ball.

Now the problem here is that the ball will be moving *fast*. So if I won't monitor the acceleration process, the momentum of the ball will damage the engine. Or even worse, the ball will damage a person. >_<;

So to make it safe I've thought up of a method of deceleration
that involves electric magnets. I've placed the magnets on the surface that the ball will be moving on, so when the speed becomes too fast, the magnets will turn on and start to attract the ball towards the surface. (Increasing the friction and pulling the ball in the opposite direction)

Several magnets of the right strenght is enough to decelerate the ball.

So, my problem is that if the magnets will be turned on at *all* times, they'll slow the ball down instantly. That's why I need to turn them on during specific times. And to find those specific times, I'm using the motion detector to find out the exact location of the ball and which magnets to turn on/off.

Is that detailed enough?

Hmm...Light beams. Sounds like a good idea. Any suggestions on where can I get a supply of the kind that will best suit the project?

Nigel Goodwin

Perhaps you should enter your location in your profile, if it's blank we can only assume English is your furst language?.

Your English is good, it's your description which is poor :lol:

A photo-diode, or photo-transistor, for the receiver, and an LED for the transmitter - arranged so the ball breaks the beam.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

HudzonHawk

Ok, one final question: Are there going to be any speed restrictions on how fast the ball can go? (eg: The ball will be so fast that the time it spends in contact with the beam won't be enough to record it?)

That would help, but at the moment I'm in England Unless there's a "Place of Birth" field in the profile.

Nigel Goodwin

It's OK, you can be officailly English! :lol:

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

HudzonHawk

Hehehe, works for me

Now to get myself some tea...

Nigel Goodwin

Not if it's from a samovar though :lol:

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

ljcox

Photo diodes and photo transistors respond in microseconds. So the speed of the ball will not be an issue.

__________________
Len

HudzonHawk

Awesome, thanks for the help guys

There are ways of making tea without a samovar? :O Inconceivable!