How can the AnyBody Modeling System handle closed chains in the model?
Bicycling is a typical closed-chain example. The legs and crank together form a closed mechanical chain. The AnyBody Modeling System handles closed chains in the mechanism, but it is true that many other systems for mechanism analysis do not. There are really two distinct problems connected with closed chains. The first problem is in the kinematics where closed chains complicate the solution algorithm because make it impossible to resolve the positions by stepping from one joint to the next until the free ends of the mechanism are reached. The AnyBody Modeling System employs a very general method for position analysis and does not rely on assumptions of open chains. The second problem is in the computation of muscle forces. The classical way of doing inverse dynamics is to compute joint moments and subsequently distribute them onto the individual muscles. When there are closed chains present, the problem of resolving joint moments may not have a unique solution. However the AnyBody Mod
