# Speed

For a project, I am trying to make a hockey puck that can calculate velocity. The only problem is that I can’t find a sensor I can use. It is also worth mentioning that the sensor should be inside the puck.

I would say this is very difficult as anything inside the puck has to survive the puck being hit . The size is also small and anything inside the puck ( by cutting into it ) is likely to compromise its strength .

Although very difficult you might be better off having something outside watching the puck move , or make a whistling puck and use dopper effect ?

It’s for a school project and he won’t let me change so I have now decided to take light shots. I had two ideas on how to do the project. using an optical sensor(I don’t know how to get around the problem of the puck spinning), or a sensor that detects the start and stops impacts and uses that to calculate the velocity.

You "might" be able to do this with a mouse laser/optical sensor (assuming the puck never gets airborne). You could use an external camera plugged into a RPi running computer vision software. Otherwise, you could use an IMU (i.e. MPU 6050) to measure forces and accelerations on the puck.

ericpyper14: For a project, I am trying to make a hockey puck that can calculate velocity. The only problem is that I can't find a sensor I can use. It is also worth mentioning that the sensor should be inside the puck.

No mention is made that a velocity is to be measured. Only be able to calculate velocity. At rest, can you calculate the velocity of the puck? I think you are complicating the assignment. How about giving us the ACTUAL WORDING?

Paul

ericpyper14: For a project, I am trying to make a hockey puck that can calculate velocity. The only problem is that I can't find a sensor I can use. It is also worth mentioning that the sensor should be inside the puck.

Hi,

Fox Television built a puck that could do this. It was a horrible flop as it drove true hockey fans to have the puck light up on their screen.

https://thehockeynews.com/news/article/20-years-later-a-look-back-at-the-foxtrax-pucks-complex-legacy

Here is the Wikipedia on the puck: https://en.wikipedia.org/wiki/FoxTrax

Not sure if your program has access to it but, there is an IEEE paper on the FoxTrax puck:

https://ieeexplore.ieee.org/document/574652

The patent is:

Cheers, GolfCartGreg (Hockey Dad)

How about the smallest microcontroller you can find and the smallest accelerometer you can find. Place them inside the puck. Have it record the acceleration over time. v = a * t

Drill a hole in the middle of the puck to fit the components plus an extra space for some extra silicon goo, which will prevent the components from too hard hits. The goo might also improve the accuracy of the measurements. Downside is that some energy of the hit will dissipate in the goo.