Determining the postion of (distance between) wrist and shoulder

Main Forum
1

Hi,

I intend to investigate specific postures of the upper extremities. In a first step I won’t use any MoCap data. To set up a posture I will define the joint position, e.g. of shoulder and elbow joint, manually. For an accurate description of each posture I have to determine:

  • distance between wrist and shoulder and
  • horizontal and vertical angel between wrist an shoulder.

Unfortunately I could find any relevant data to solve my question yet.

Thanks for your support.

Kind regards,
Stefan

2

Hello Stefan,

there are probably different ways to measure the things you want to measure. You could calculate a geometrical vector from the shoulder, e.g. from the location of the glenohumeral (gh) joint to the wrist segment,


AnyVec3 ghwristvec = Main.HumanModel.BodyModel.Right.ShoulderArm.Seg.Scapula.gh.r - Main.HumanModel.BodyModel.Right.ShoulderArm.Seg.WristJointSeg.r;

and calculate the the distance as the length of this vector (function vnorm) and the angles by you could calculate as the angles between this vector and the global reference frame if it fits to your body positioning or maybe to the reference frame of the thorax by using scalar products and the acos function.

Hope that helps solving your problem.

Best regards
Daniel

3

Hi Daniel,

thanks for your help! It has been quite easy to set up the measurment.

regards,
Stefan