HELP!!!
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HELP!!!

by rc.ryan8 on Thu Jan 24, 2013 7:11 pm

I am looking to make a simple golf simulator much like the optishot without the video. I am thinking that if I use two rows of sensors one before the ball and one after that I should be able to find swing speed given the distance it takes the club to get from each sensor. I was hoping someone could give me a little help on what sensors would be best for this project and what Arduino I would need? I think that I am going to need something that I can program so that it can display swing information on a screen. Thanks For the Help
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Re: HELP!!!

by franklin97355 on Thu Jan 24, 2013 10:39 pm

Design your sensor array before you worry about the processor. Once that is done you can move to the next step (how you want the data displayed and what formulas you need to compute that)
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Re: HELP!!!

by adafruit_support_bill on Fri Jan 25, 2013 6:18 am

Optical sensors are probably what you want for this. Some phototransistors aligned with laser diodes on the opposite side of the club path.
As Franklin says, design the sensor array first. Figure out what the timings will be for the range of club speeds you want to measure and how you want to display them. From that information you should be able to determine the requirements for your processor.
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Re: HELP!!!

by rc.ryan8 on Fri Jan 25, 2013 9:42 am

I was thinking about getting the ADXL335 - 5V ready triple-axis accelerometer and putting those of either side of the ball. I was thinking this should be able to get me a accurate reading
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Re: HELP!!!

by adafruit_support_bill on Fri Jan 25, 2013 10:14 am

You would only need one ADXL335 for that. But you would probably need a gyro too unless you can prevent the ball from spinning. In any case, there are a couple of potential issues:

1. You would have to make sure that the club hit the ball and not the sensor. If you could figure out how to get the sensor inside the ball, that would help.

2. The mass of the sensor will affect the acceleration of the ball off the club. Unless it is perfectly balanced, the spin will be affected as well.

3. Unless you plan to put a radio transmitter in there too, the stress on the wires is going to make that a reliability issue.
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Re: HELP!!!

by rc.ryan8 on Fri Jan 25, 2013 10:29 am

I dont see anyway I could put a sensor in the ball without putting the weight of the ball off and effecting the shot. Is there anyway I would put the Gyro after the ball or under the ball and still get an accurate spin reading in the millisecond that the ball is hit and still over the sensors reading range?
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Re: HELP!!!

by adafruit_support_bill on Fri Jan 25, 2013 10:39 am

Gyros and accelerometers would have to be attached to the ball to measure its acceleration & spin.

The optical array proposed earlier sounds like the most practical approach.
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Re: HELP!!!

by rc.ryan8 on Fri Jan 25, 2013 10:42 am

Having something attached to the ball isnt a possibility. Is there any other way I could have a sensor before the ball and a sensor after the ball that could tell when my club moves over them and then from this I could figure out swing speed?
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Re: HELP!!!

by adafruit_support_bill on Fri Jan 25, 2013 10:53 am

Yes. The phototransistors and laser diodes suggested earlier will do that. The club will break the beam when it swings between them and the phototransistor will detect that.
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Re: HELP!!!

by Zener on Fri Jan 25, 2013 1:33 pm

I am assuming they will use whatever putter thay have, not a special one.

Easiest way might be put some reflective tape on the bottom of the putter and have 2 reflective sensors in your Astroturf (or whatever). That will give you club speed. As far as spin etc I don't know. That gets more complicated.
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Re: HELP!!!

by adafruit_support_bill on Fri Jan 25, 2013 1:40 pm

It's not clear that he needs to measure spin - unless he's using an accelerometer. You would need to know how much of the acceleration was due to straight-line acceleration and how much was due to the spin.
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Re: HELP!!!

by Zener on Fri Jan 25, 2013 1:47 pm

Re-reading the original post the spec is just to find speed. I know some guys who did something similar, and they used an Arduino and a display shield with 4 buttons on it to enter different setting and go through some menus they had.
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Re: HELP!!!

by Metaphysicist on Sun Feb 03, 2013 4:23 pm

This is my first post, and I can't be of great help because I am more of a Linux and UNIX guy than an Arduino guy (getting in to it though!).

I once worked for a company that sold golf simulator technology, I designed racing simulators and motion control platforms (nothing too sophisticated), and occasionally had to diagnose the golf simulators.

Here is a brief description of what I remember the system looking like:

There were three bars of sensors, two about four inches apart from one another and a third about a foot ahead like this..

___Sensor Bar 3___



___Sensor Bar 2___
___Sensor Bar 1___

Bar 1 and 2 were light sensors, we had a bright light above them so when you swung your golf club it would break the connection and report, this would determine your swing speed and angle, the third bar was for putting because bar 1 and 2 worked in conjunction with a microphone system and an absorbent screen to measure the speed of the ball using trilateration(triangulation? sp?). I know that it used basic serial, the data was very small, and it was actually a separate PC that ran in DOS. When you hit a ball, the first bar would go off, the second bar would go off, and then the ball would hit the screen. So initial speed, through speed and angle relative to the first sensor bar (both had two rows of two sensors almost the width of a golf ball but a little thinner, I don't know if partial readings happened from the sensors or not), and then a microphone above the screen, and two on either side of the screen that would determine the position of the ball against the screen in relation to your initial sensor bar readings and give you the correct vertical trajectory (after getting the initial horizontal angle from the two sensor bars) and mash it all together. As far as curvature (these simulators didn't measure spin) it had something to do with the angle first created from the two sensor bars, and then some form of interpolation based on the position of the ball on the screen. So (this is an example) if the club face and ball were going at say a 15 degree angle toward the right of the screen, but it hit a few inches right of center of the screen, it would determine the curvature of the hit and continue that curved line based on the two sets of measurements.

I don't know if this was any help but I actually found a post I felt I could contribute to, let me know if you have any questions, my memory is a little rusty but I played with them enough that I should be able to help.

Oh, and this was designed so anyone could use their own clubs and balls without having any special equipment.
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Re: HELP!!!

by Metaphysicist on Sun Feb 03, 2013 4:27 pm

That should read each sensor bar had two rows of sensors (it had I think close to 20 per line?)

So one sensor bar looked like this from above:

o o o o o o o o o o o o o o o o o o o o
o o o o o o o o o o o o o o o o o o o o
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Re: HELP!!!

by Metaphysicist on Mon Feb 04, 2013 11:51 am

Come to think of it they definitely had partial readings of the photovoltaics because the ball position was near perfect. They also could calculate club face angle when it passed over also to the tenth of degrees.
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