Feasibility of swim lap counter

Current swim lap counters are watches and rings. I'm not a fan of wearing these, and they require stopping to read.

Looking for some direction/advice on the feasibility of an idea.

I'd like a small, 4 digit display hanging in the water that increments each time I go 50 meters (two lengths). I don't want to have to touch something, so I'm wondering if there's a sensor I could wear where an Arduino could read when I'm within 3–4 feet of it. I'd guess there's a 2–4 second window when I'm within that distance. If It senses me there, and has been more than 10 seconds since the last time, it'd increment.

I've got programming experience, and have always wanted to work with hardware. Any ideas on if this could be done, and if so, what sort of sensors and hardware would I be using? Any advice on what the setup would look like welcome.

It's tempting to suggest using RFID, but that wouldn't work through water. Could you arrange to carry an RFID tag in such a way that it was out of the water when you passed the sensor? I guess the sensor would be at the end of the lane, where you are turning.

PeterH:
It's tempting to suggest using RFID, but that wouldn't work through water. Could you arrange to carry an RFID tag in such a way that it was out of the water when you passed the sensor? I guess the sensor would be at the end of the lane, where you are turning.

Yeah, I figured RFID was off the table. I'm doing flip turns, so body parts are briefly out of the water, but nothing that would be close or accurate enough to read RFID from what I've seen.

Are there any two sensors/radios/etc that could talk/read/connect to each other when within that 3–4 foot proximity? (with one or both underwater)

idea:

  • As water is transparent for light you could lay a mirror on the bottom and have a laser pointing at it and measure reflection?

  • A TSL235R light intensity sensor might be able to detect a shadow ?

robtillaart:
idea:

  • As water is transparent for light you could lay a mirror on the bottom and have a laser pointing at it and measure reflection?

  • A TSL235R light intensity sensor might be able to detect a shadow ?

I wish! Unfortunately, I'm at a gym pool, so putting together a mirror and laser setup 10 feet down each day probably won't fly. I also have to share a lane on some occasions, so I'm not sure motion detection would be a good fit either. This is why I've been thinking there would have to be a sensor that I am carrying.

Is there any sort of setup where two small sensors would be able to identify their proximity to each other? (or, if they're simply within a certain proximity in general)

Is there any sort of setup where two small sensors would be able to identify their proximity to each other? (or, if they're simply within a certain proximity in general)

If so, I'm sure that they would have been suggested by now. That none have implies that there aren't. And, if you think about it, the sensors would have to be able to communicate with each other, meaning that both need to be powered. You want to swim around with a battery strapped to your wrist?

Now, you could use a ping type sensor at the end of the lane, to determine when you, or anyone else, is close. They come in a variety of cone angles, to limit how far off center an object can be before it triggers the sensor.

The problem that I see is that anyone approaching the sensor would trigger it, which may make it impractical.

PaulS:
If so, I'm sure that they would have been suggested by now. That none have implies that there aren't. And, if you think about it, the sensors would have to be able to communicate with each other, meaning that both need to be powered. You want to swim around with a battery strapped to your wrist

Just kicking around ideas—I'm open to anything powered or not. Kind of assumed it'd have to be powered. I haven't delved too deep into the Arduino community and assumed there had to be some sort of pair of sensors that could tell when they were within a few feet of each other. My thought is that if I can get something that works, I can whittle it into a more aerodynamic design afterwards.

rwrwrw:
assumed there had to be some sort of pair of sensors that could tell when they were within a few feet of each other.

In air, no problem. But unless you can rely on getting the mobile part out of the water at the appropriate time, I think you're going to struggle to get any RF based system working.

Just found this searching for other stuff regarding Arduino and swimming.

Did you ever figure out a way to do this?

One thought I had was an ankle bracelet with a magent on it and some kind of Hall effect sensor (since your feet always need to touch the wall if you are doing flip turns), but I don’t know about sensitivity and working through water.

rwiens:
Just found this searching for other stuff regarding Arduino and swimming.

Did you ever figure out a way to do this?

One thought I had was an ankle bracelet with a magent on it and some kind of Hall effect sensor (since your feet always need to touch the wall if you are doing flip turns), but I don't know about sensitivity and working through water.

Sorry, no luck on it.

How about a small heads up display in your goggles?

Or something you wear, when it senses you turning you get a message via earphone.

Someone mentioned that your feet touch the pool wall when you turn. If this is true, then could you hang a flat sensor board over the pool edge? A pressure activated switch could be used to increment a counter and a display (in a waterproof container) could be embedded in the board to display the laps underwater. A simple non-retriggerable one-shot multivibrator could be used to de-bounce the switch closure.

This is effective if someone had a personal lane. The touch pads are already in existence for races and events, though most are bulky.

Much of the time—in my case at least—lanes are split in half when I'm at a public pool. Which is why I was seeking a personal, portable solution that could clip onto a suit or goggle, or some sort of band that could be worn.

Someone mentioned that your feet touch the pool wall when you turn.

In an official game they should, if you don't you will loose speed too BTW

familiar with this - http://www.optitrainer.com/ - ?

I read an article, not sure where I found it (elektor magazine maybe?) that was Arduino based, used an accelerometer, maybe a gyro, mayye both, that started counting time when motion was sensed, counted laps when change of direction was sensed, and autopowered off when change of horizontal to vertical orientation was sensed.
Worm on the body with a belt, armband, something like that. Could be made very small with a custom board, add small screen for reading results, or uUSB for downloading.

rwrwrw:

[quote author=Papa G link=topic=134762.msg1242367#msg1242367 date=1368724225]
Someone mentioned that your feet touch the pool wall when you turn. If this is true, then could you hang a flat sensor board over the pool edge? A pressure activated switch could be used to increment a counter and a display (in a waterproof container) could be embedded in the board to display the laps underwater. A simple non-retriggerable one-shot multivibrator could be used to de-bounce the switch closure.

This is effective if someone had a personal lane. The touch pads are already in existence for races and events, though most are bulky.

Much of the time—in my case at least—lanes are split in half when I'm at a public pool. Which is why I was seeking a personal, portable solution that could clip onto a suit or goggle, or some sort of band that could be worn.
[/quote]
Okay, I see.

Water and air have similar magnetic permeabilities so perhaps a very strong magnet could be worn on your wrist or ankle and sensed by a coil of wire near the pool end wall. Suitable de-bouncing (seconds) would prevent multiple triggers during the turn.