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I'm working on a project to make a SmartBall that can detect the velocity(km/h) , spin(degrees per second) and flightpath(trajectory) of the ball using Intel Edison with the 9DOF block (LSM9DS0 : 3-axis accelerometer, 3-axis gyroscope, and 3-axis magnetometer) & the battery block, I'm reading values from the 9DOF block by RTIMULib(Library for IMU chips). I've been working on integrating the acceleration data from the accelorometer to get the velocity then get the position, I know that this method is not really accurate as the integration error cumulate very fast but I rely on that my calculations will be done in a very short time (about 3 seconds) then i re-calculate again from the beginning after every kick so that error doesn't cumulate hardly, Also i only need an acceptable accuracy not a very high one. I discovered then that i'm dealing with projectile motion(ball kicking), so after considering this & searching in projectile motion equations i found that i must know the initial velocity and the angle of projection(theta) to be able to get my requirements. my problem that I don't know how to get any of these , I tried different approaches like getting the horizontal distance & getting the height to get their resultant(using pythagoras) then get the angle(assuming it's a right angle) in a very small time at the beggining of the projection , but i still couldn't get the height. The gyroscope outputs roll, pitch & yaw angles related to the sensor orientation but i'm still not using this as i'm assuming that the sensor will be fixed inside the ball so it's orientation will not be the same as the projection angle.Now What I really want is any approach/idea on how to get velocity & flightPath of a projectile using accelorometer and gyroscope data. Hope I made it clear , Any help on how to get my requirements is really appreciated, Thanks so much.

H.Z.
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    Can you be more specific as to what problem you're trying to solve? that will help us come up with a better answer. – Mark Omo Apr 29 '15 at 03:22
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    I think one of your big problems is if the ball is kicked with spin, it will be difficult to know the direction of any accelerations it encounters afterwards. Or are you just trying to record the initial impulse of the kick and predict the height/distance it travels? (Have you searched for any references on instrumented soccer balls by the way?) – Andy Apr 29 '15 at 08:26
  • @MarkOmo Hello Mark, Thank you for responding. my problem is that I do not figure out how to use the accelorometer & gyroscope data to get velocity and spin in projectile motion – H.Z. Apr 29 '15 at 16:44
  • @Andy Hello Andy, thanks for responding. I guess your 2nd assumption is the one i'm looking for, Yes I did but that wasn't handy for me as the ideas are different from mine , I only want to use the acceleration data and orientation data to get the velocity and spin in projectile motion by anyway – H.Z. Apr 29 '15 at 16:44
  • I would try to implement a simple Kalman estimator for the spinning problem. You can take a simple linear one with is from the calculation point of view simple to achieve a pretty high samplingrate with the drawback of have low accuracy. Then you can project the acceleration vectors to the realworld (you have all the information you need about the orientation). At the last you need to integrate the acceleration data and it's done. In addition you can use other estimators/filters if you do not like kalmans. – TobiasK Apr 30 '15 at 08:54
  • Or develop a kalman estimator with can estimate the position on it's own. But this thingy will be non-linear and I'm not sure whether you find lot of research about this topic. For both approaches I suggest to use the magnetometer measurements, too.... will be way more robust. – TobiasK Apr 30 '15 at 08:57
  • I'm also interested in this problem..could you tell me if you managed to get any results? – iuri May 07 '17 at 13:29

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