Hello everyone,

This is my first post here, so if I'm doing anything wrong please let me know!

I've got a signal on a force plate, the subjects are jumping then landing. I get the z and x components of the force along the time.

I'd like to integrate to get the speed (+ the take off angle), and then the position. The theory is simple : F-mg=ma. I'm doing a trapezoidal integration.

My problem here, is that speed and position should go back to zero at the end, and it's not. If I manage to share a picture you'll see that Vz is not too bad, but Z is terrible. That's even worse with Vx, and X is total non sense.

Do you have any idea how to prevent that drift? I would tend to think it's a common issue in movement sciences but I can't find anything about it. How do biomechanics software do?

Thanks in advance!