Magnetic Field Sensors in Goal Line Technology

Have you tried a google search on "hall effect devices". They are a little electronic device that can be used to detect the presence of magnets. They may be suitable for your project. Another option would be (perhaps) pressure sensor(s) that detect the impact of the puck on the back of the net. Perhaps you could try turning the hockey net into a large "metal detector", similar to the handheld ones used to find metal underground (it is possible).

Just a few ideas that may point you in the right direction (or give you a slightly different perspective on what is possible).

The problem I am having with hall effect devices and magnetic field sensors is finding a product that will cover the entire opening of the goal. Pressure sensors are out because we need to know the instant the puck crosses the line. I like the metal detector idea and I'm going to investigate that further.

Thanks for your input. I am open to other opinions so please keep replying.

You probably won't find a product that will do the entire opening of the net (there are exceptions, each with their own advantages and disadvantages). Don't dismiss the possibility of using two or three of the same sensor (one on each side may give you enough range to cover where the puck is most likely to be or end up if hit into the net).

Also remember that you want a fit-for-purpose design. The puck may enter the net airborne but it wall always end up on the ground. Is it necessary to do a complex design with a complete opening sensor coverage that will handle sensing an airborne puck as it enters the net? I will leave you to think about that.

I try to work on the KISS principle of keeping it as simple as practical (less to go wrong when you try and implement a design in the real world). Of course you could use a couple of small wireless transmitter/receiver modules if you had to get the puck location data to somewhere else (although this may be too complex and not particularly useful), or you may not need to transfer this data away from the net at all.

Here's the inverse of what you need

Invisable Fence, such as you would use to keep a dog in your yard

I suppose you could make the output latch on & light up the puck

Some RFD tags work by going through a wire loop. I don't know the accuracy but it's a possible avenue.

Brad

The problem you have to overcome is distance. I would recommend that you use a large coil at the opening to the goal to energize coils with two or three planes of orientation within the puck which would cause the puck to switch on an RF transmitter that signals it's detection. This probably isn't practical and there are problems with "near" misses. You could possibly detect a phase reversal as the puck went through a node in the field set to be at the boundary but you still have issues with the puck not being regulation with active electronics inside it. But you might be able to use a piezoelectric device inside the puck to power it from being struck so it could be potted solid without any opening required for batteries.

Good luck, you picked a very difficult application. Maybe high speed video cameras with image recognition and movement tracking software to "see" the puck go by. Or a laser curtain that flashed some imbedded phosphor compound that was detected by a photo-multiplier behind an optical filter? Hey, light is electo-"magnetic" radiation!

There are electronic pucks already in use, I have no idea what they cost, I believe that they send out a radio signal (to allow TV cameras to track them in some way), if so, they will save you trying to design electronics that will survive a match ( you also need to design a power source if starting from scratch!!

Otherwise the RFID idea might be a good place to start!!!

I can't offer any engineering solutions.... Just remember that to count as a goal the ENTIRE puck must cross the goal line. What if the goalies pad is covering the puck thus disturbing any beam type technology?? Try taking the weight of the puck to trigger sensors in the ice.

There are a lot of pitfalls in this project. You have to be able to detect an object passing inside of an incomplete loop (the goal cannot be hardwired through the ice; it must be able to pop out to avoid injury should a player run into it). Weight sensors won't work, since the puck might be airborne.

I would suggest some research into gauss detectors might be in order. Gauss meters use directional loop antennas to look for electro-magnetic fields. Another avenue would be the degaussing systems used on navy ships to avoid detection by magnetic mines. The mines react to local disturbances in the earth's magnetic field. The degaussing system monitors the local field, then adjusts the current through large coils in the ship's hull, exactly counteracting the disturbance caused by the steel ship. It would take some finesse with the puck to come up with a magnetic anomaly which you could differentiate from the steel in the players' uniforms, yet still weigh, slide, fly and rebound like a normal puck. Maybe a magnet in the core of the puck? You could install the gauss antenna into the 3 sides of the goal frame to detect any anomaly, and tune it to alarm exactly one puck diameter inside the frame.

Optical will be fast/Sure/cheap. Magnetic MAY BE possible but errors will be plenty.

2 identical LED/Laser transmitters+reflection Sensors. At 2 Goalposts

Goalmouth melees and pad reflections can be softwared out.

Digchip will give you monthly new LED's,Sensors Logic Chips.

You need a task force.

Do not try DIY-- unleess you are a circuitry juggler.

The electronic puck already exists. It was created to make it easier for TV viewers to see the path and position of the puck. Hockey purists killed the idea. Details are at the following web site:

http://en.wikipedia.org/wiki/FoxTrax

RfI chip with antenna taped to inside side of goal did some thing similar on a wide doorway it worked i got payed

nick

ca.

If I were you I wouldn't mess with magnetic detectors. too many ferrous metals around to cause dead calls.

Do a little research on RFID technology. it is simple and error free. the puck includes a passive transponder and will make the call only when inside the net. obviously it is a custom made puck, but the transponder is minute and will have no effect on the puck specs. Same technology as used against shop lifters. What I am not sure about is the "G" limits of the transponder, but I guess this a paper exercise anyhow...

Wangito.

Nope I actually have to build it. Do you know anything on the directional RFID will it have to be so to only detect in the net?

The Wiki explanation http://en.wikipedia.org/wiki/RFID pretty extensive!

Here's a description of a system doing the same thing you are to accomplish.

http://www.rfidjournal.com/glossary/electronic%20article%20surveillance

Have fun

There are systems that use Surface Acoustic Wave (SAW) devices. When targeted with a microwave signal, the energy would propagate across the chip, be superimposed with a code and then re-radiate back to the polling source. Presumably, you might be able to shape the pattern of the antenna to create some sharp boundaries.

Just google: SAW RF ID