I have a need for speed!!(literally)

Erik G

Hey all, i have a few quick questions that i need a little help answering. I want to measure the swing of a golf club. I have thought about using IR and receiver pairs spaced foot apart and by measuring time and dividing distance by it, voila i have my speed. Now then i started thinking more and more and thought hmmm,.. how could i also get the angle of the club face?

I have a few ideas and tell me what you all think.
1) use the IR pairs, except now there would be two at each sensor pair like three colons right after each other
for example. : : : where by measuring the time between passing the top and bottom pair of and dividing by the total speed would give distance and by knowing that the top and bottom IR pair are say 2 inches apart, by using pythagorians theorem i could get the angle. I swear, it makes sense in my head.

2) How about the ping sensor? could i measure speed with that? i am truly mainly just looking for a way to do speed first. The angle can come later. Most of what i have read about the ping))) sensor is that it is mainly for distance. what do you guys think?

3) finally i have thought about using the memsic dual axis accelerometer. mounting it somehow on the club with the basic stamp somewhere on it too somehow, but with that be able to get the rotational acceleration and ultimately with some math get the speed at the golf ball. also if i mounted it on its side i think i could use the tilt to get the angle of the club as it was hitting the ball, using similar tactics as getting the speed with the rotation. So what do you think? Can the accelerometer be mounted sideways, is it accurate enough to get the data i need?

Thanks for your ideas guys.Just let me know if you need more info or if you need clarification. Cheers!

DogP

Speed could be done like you say with sensors that the club breaks the beam... IR sensors, or something like laser trip beams would probably work well for that. I don't know that the Ping sensor would be as good, since you really don't need to know range from the sensor, you just need to trip a few beams to be able to compute speed.

Rotation of the club would be tougher, since adding a device to the club would probably change the feel... I think you'd want to add it at the top of the club to have the smallest effect (and everything could be computed from that, since the club is a rigid body). I don't think an accelerometer would work well though, since it can't detect rotation parallel to the ground, which is what the angle of the club face is. A better option may be a 3 axis gyro sensor, since that'll detect rotation. Try one of the early golf games for the Wii, and then try one of the newer ones that uses the MotionPlus and you'll see the difference. The Wii Remote has a 3 axis accelerometer on it, and the MotionPlus is a 3 axis gyro, and the gyro makes all the difference.

There may be a better way to do it though, maybe using the same type of idea as the first, except use a tight spacing of sensors to detect the "thickness" of the break of the beam. If it's thin, then the club is parallel to the beams... if it's thick, then the club is rotated.

DogP

Manetheren

Either that or completely gut the head of the club and instal some electronics ( prob gyros) and make it weigh the same. This would let you check the whole arc of the swing along with the speed. Though you would loose the use of one club.

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Tia'Shar Manetheren