1 Topic by KephreN

  • KephreN
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Hello guys,

I'm mostly using kinovea with weightlifters. Currently, I have to export vertical speed and accel data separately and use the weight to calculate the resulting instantaneous vertical force, work and power.  I then add the gravitational force to find out what is the lifter's vertical force on the barbell and calculate his power.

So far, I'm using this, but I could be wrong as I'm no physician.
Fy_total= m*a = barbell weight (kg) * Ay from exported graph data = Fy_lifter - Fy_gravity
So Fy_lifter = Fy_total + Fy_gravity. I then use Fy_lifter * vertical_velocity to measure power.

I wish I could input the object's weight and calculate the data automatically.

Unrelated to this idea/request, is there a way to plot various data from the same trajectory on the same graph, or do I need to use 2 different paths on the same image?

Regards

2 Reply by joan

  • joan
  • joan
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Yes kinetics computations would be nice, but we must be careful at not giving a false sense of accuracy… Any prior art showing how accurately this can be measured from video alone compared to a ground truth would be nice.

For example the acceleration is usually very approximate. We tested against the gravity ground truth by tracking a falling ball, and you have to have a very controlled environment to get correct results.

At the moment you cannot export speed and acceleration simultaneously on the same graph. I don't think having two different paths would help, you'll see the two trajectories in one graph, but still only one graph for each kinematic value. This would probably require a dedicated exporter with some options because some people will want the data sources in columns and others will want the type of data in columns.