# Using your phone to determine disc speed?

#### Bart Bird

##### Newbie
We are working on a system that helps players find discs that are a good match for their current release velocity.

The "easy" way to determine exact release velocity is with a radar gun, but (of course) very few people have one.

Does anyone have any ideas on how people can use their smartphone (or something else?) to determine the speed of a flying disc?

I've found a number of baseball apps that do something similar but nothing I've found seems to be a good fit.

speed = distance / time.

Frames per sec with slow motion should be defined by phone, example iPhone 120 fps
Set distance = measure out point of release to 10 feet.

Seems doable to me.

^this. You can get real scientist on it and make a board with equally spaced lines and use that as a backdrop while you record the throw.

speed = distance / time.

Frames per sec with slow motion should be defined by phone, example iPhone 120 fps
Set distance = measure out point of release to 10 feet.

Seems doable to me.

Thanks for the input!

I like the track you are on because it doesn't require any special gear -- making it easy for anyone to do at their home course.

Phone, tape measure, and a set of simple instructions. It could work!

^this. You can get real scientist on it and make a board with equally spaced lines and use that as a backdrop while you record the throw.

Thanks -- there's no doubt your idea would be accurate.

To clarify, this is not for our internal research -- we actually do use a radar gun for our testing -- very accurate, and it captures max speed vs. average speed over a span.

Our goal for this project is to find a way for the average player to determine their speed at their home course without needing a lot of extra gear.

Any thoughts?

Would require two people, but maybe you could create an algorithm that can determine disc speed based on a video of the disc coming at the camera. As the disc gets bigger, it's getting closer. Using frame rate and a separate algorithm to isolate the disc in the image, you could calculate the speed of the disc using lots of maths. Maybe even use the devices sensors to determine the tilt of the phone to correct for any parallax error.

Last edited:
. . . -- we actually do use a radar gun for our testing -- very accurate, and it captures max speed vs. average speed over a span.

Our goal for this project is to find a way for the average player to determine their speed at their home course without needing a lot of extra gear.

Any thoughts?

It seems like a \$65 radar gun (less than \$40 used, off eBay) is probably going to be the best option.

As a current EE (electrical engineering) student, my brain has been abuzz with ideas for disc golf tech. I'm sure I'm not alone nor the first to ponder this, but I'd love a small RF or bluetooth widget that could be slapped to the bottom of the disc that could gather data such as spin, speed, acceleration, and plot all that data over some graph on a smartphone app... you could play with the axes and then graph acceleration over position, spin vs speed, etc. All kinds of fun data could arise. Even more fun would be to see the disc speed and acceleration data versus the distance or position the disc widget is from the 'brain' (your smartphone in your pocket), like if it could animate an overhead realtime rendering of your arcs, where the disc is going and what it's doing...

Anyways Bart, sorry, I got nothing for you at the moment. But if you know any disc golfing venture capitalists, please let me know

As a current EE (electrical engineering) student, my brain has been abuzz with ideas for disc golf tech. I'm sure I'm not alone nor the first to ponder this, but I'd love a small RF or bluetooth widget that could be slapped to the bottom of the disc that could gather data such as spin, speed, acceleration, and plot all that data over some graph on a smartphone app... you could play with the axes and then graph acceleration over position, spin vs speed, etc. All kinds of fun data could arise. Even more fun would be to see the disc speed and acceleration data versus the distance or position the disc widget is from the 'brain' (your smartphone in your pocket), like if it could animate an overhead realtime rendering of your arcs, where the disc is going and what it's doing...

Anyways Bart, sorry, I got nothing for you at the moment. But if you know any disc golfing venture capitalists, please let me know

Ha! No, I haven't found any VC groups interested in our sport yet, but I'll keep an eye out!

I agree on the tech -- I am also looking to see what other tech/gadgets/apps are out there that could be adapted for disc golf.

There is a lot around ball golf and baseball, but I haven't found anything yet that seems like it could be used for disc golf.

Thanks -- there's no doubt your idea would be accurate.

To clarify, this is not for our internal research -- we actually do use a radar gun for our testing -- very accurate, and it captures max speed vs. average speed over a span.

Our goal for this project is to find a way for the average player to determine their speed at their home course without needing a lot of extra gear.

Any thoughts?

What speeds have you found for typical players across the skills? My guess would be 55ish for average guys who play a lot, 58-62 for advanced, and 65+ for open. With new players anywhere low 40's to 50ish and elite in 70ish.

What speeds have you found for typical players across the skills? My guess would be 55ish for average guys who play a lot, 58-62 for advanced, and 65+ for open. With new players anywhere low 40's to 50ish and elite in 70ish.

Average distances by skill-class can be really skewed, but average distances by disc speed give us some pretty good numbers.

On average, a 60mph drive will travel about 350 feet. The standard deviation, though, is pretty big.

With a great throw, a wobble-free release, and the right disc stability for the air-speed, 60mph drives can go over well over 500 feet.

.....but some players throwing 60 barely hit 225.

That's one of the things we want to dial in -- if you know what your throw velocity is, you can compare your distances to the averages, then develop a path forward to find a combination that allows you to consistently beat the averages for players with your same release velocity.

You should be able to use the diameter of the disc to help with your distance calculation through the camera. All of that information is available, so the user should only have to input the disc that they're throwing before the throw. Yes, I know there are angles to worry about and how the person is holding the disc, but it could be a starting point.

There are accelerometers in probably every smartphone on the planet. Have the person use the phone like it's a disc and use the libraries centered around velocity (probably could look around some auto forums to look for help with those) to measure max velocity. Build a matrix centered around that value and the disc speed it corresponds to.

Then you could start collecting data from reach back to pull through to snap and help people grow their disc speed.

To add to the above, you could also pretty easily determine the hit (when else is the phone going to accelerate on that plane so rapidly like that) and check the orientation of the phone to try to determine the nose orientation at release.

Yes, I'm aware that the method I'm proposing could wind up seeing a lot of phones needing to be replaced.

There are accelerometers in probably every smartphone on the planet. Have the person use the phone like it's a disc and use the libraries centered around velocity (probably could look around some auto forums to look for help with those) to measure max velocity. Build a matrix centered around that value and the disc speed it corresponds to.

Then you could start collecting data from reach back to pull through to snap and help people grow their disc speed.

Amazon has bluetooth accelerometers fro \$25 or \$30. I'm not sure you can determine velocity from an accelerometer because they only measure a difference in acceleration.

Amazon has bluetooth accelerometers fro \$25 or \$30. I'm not sure you can determine velocity from an accelerometer because they only measure a difference in acceleration.

The difference in acceleration at the hit?

Amazon has bluetooth accelerometers fro \$25 or \$30. I'm not sure you can determine velocity from an accelerometer because they only measure a difference in acceleration.

So fasten it to your wrist?

Replies
78
Views
5K
Replies
6
Views
320
Replies
12
Views
3K
Replies
17
Views
989