THE SR STANCE: AFFECT OF JOINT ANGLES ON COM


I have been asked how the position of the components of the body in relation to each other and joint angles of the SR stance affect the position of Center of Mass. This is an important issue. So, I am providing some reference material in this post before I post on rounding the back and shoulders in an SR Stance.

I use several software programs for illustrations that I have not seen used by others in material on ski technique and skiing. My 3 goto software programs are SmithMicro Poser, Visible Body Muscle Premium and Graphic. Poser and Visible Body Muscle Premium allow me to create 3-dimensional graphics that I can present from any angle I want.

The graphic below, used in my last post, was generated with Poser.

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Poser enables me to apply real life constraints on joints, inverse kinematics and Centre of Mass.

The graphic below shows that happens when I apply a feature in Poser called Auto Balance. The circles at the feet represent CoM. The circle at the feet of the left hand figure is a little faint because it is white. But in an erect or what is sometimes called a miltitary stance, CoM lies just in front of the ankle.

The right hand figure is the initial rounded back-shoulder position of the SR stance. At this point, you need to move forward in the hips to cause CoM to move to the balls of the feet so as to maximise pressure on the balls of the feet and SR response.

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Now for the fun part. Auto Balance is a little touchy. But here is what it can do if one is careful

With Poser, I can view a scene from any angle I want. The graphic below looks down on the same the same scene. Note the green dots showing CoM.

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The graphic below looks up on the same the same scene. Views like this in real life are only possible when subjects are standing on a glass floor.

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Poser 11, by SmithMicro Software, is currently on sale at $349.99 US (regular price $499.99) – my.smithmicro.com

2 comments

  1. This figure has to tuck in his tail bone to get into a position where he can initiate movements required for modern skiing I don’t know the Bio mechanics, I assume you do. It would also be interesting to hear how SR works with pronation.

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