View Full Version : Closed chain dynamics models

06-11-2004, 04:02 PM
Dear Biomch-L,

I have successfully created open chain rigid body models of the human body
(dynamics) to study the biomechanics of movement. Such models have been used to
study the dynamics of cricket bowling and throwing. I am a little handicapped by
the software that I am using, but I have now turned my attention to the golf
swing. The difference is that this needs to be modelled as a closed chain link
segment model - the hands and the club form a closed chain. I have been using
spherical constraints to connect the segments (distal point coincident with the
proximal point of the adjacent segment) and 3D rotation lock constraints to
describe the angular orientation of the segments (Euler angles). This works well
for open chain systems, but in closed chain systems, the number of constraints
exceeds the number of degrees of freedom, and the system is overconstrained, and
the equations cannot be solved by the software. Generally, the number of
constraint equations exceeds the number of degrees of freedom by 3 for simple
closed chain systems using the above mentioned choice of constraints.

My objective is to solve dynamics models of such closed chain models as golf and
olympic weight lifting. I would appreciate any information which would help me
resolve this matter.

Dr. Rene' Ferdinands
Department of Physics &
Electronic Engineering
University of Waikato
Private Bag 3105
New Zealand

To unsubscribe send SIGNOFF BIOMCH-L to LISTSERV@nic.surfnet.nl
For information and archives: http://isb.ri.ccf.org/biomch-l
Please consider posting your message to the Biomch-L Web-based
Discussion Forum: http://movement-analysis.com/biomch_l