Hi Prabhav

There is a tutorial about these options, please see

http://www.anybodytech.com/691.0.html

In the reference manual on page 269 (AnyBodyStudy) i have found the text

below concerning the InverseDynamicAnalysis

Inverse Dynamics: The inverse dynamics problem is solved by an optimization

approach that minimizes

some muscle performance criterion with respect to the unknown forces of the

system.

The equations of motion, i.e., the dynamic equilibrium equations, enter the

problem as constraints, as well as the condition that the muscles cannot

push.

In AnyBodyTM the basic performance criterion is the maximal muscle activity,

where the muscle activity is defined as the muscle force divided by the

current muscle strength. The problem is solved iteratively eliminating

uniguely determined muscles and redundant equations after each step of the

iteration. The optimization in each step can be handled with different

solvers according to the RecruitmentSolver attribute. Basically these

solvers can be divided into linear programming (Simplex) and quadratic

programming (QP) algorithms. The numerical library OOSol, which is used by

AnyBodyTM contains both a Simplex and a QP algorithm. Furthermore, a simplex

algorithm based on algorithms in the book Numerical Recipes in C++ by Press

et. al. The attribute RecruitmentSolver allows you to select either of these

three algoritms with value names composed of the library name (OOSol or NR)

and the algorithm type (simplex or QP). The MinMaxSimplex is the default

simplex solver, which currently is MinMaxOOSolSimplex. Both types of

algoritms feature a penalty setting that can assist in making the problem

better conditioned. In addition these penalties can be used to change the

appearance of the problem: A large penalty in the linear formulation of the

problem makes the problem converge towards a linear problem, i.e.,

minimization of the sum of muscle activities. A large penalty in the

quadratic formulation makes it a minimization of the sum of squares of

muscle activities. Solution in terms of muscle forces can be obtained using

a model where all muscle models have constant strength equal to one.

Please ask again if you have further questions.

Best regards

SÃ¸ren

From: anyscript@yahoogroups.com [mailto:anyscript@yahoogroups.com] On Behalf

Of Prabhav Saraswat

Sent: 14 November 2007 22:14

To: anyscript@yahoogroups.com

Subject: [AnyScript] OOSOL library??

Hi,

I have a question about muscle recruitment options.

AnyMuscleRecruitmentSolver has 4 options for using either

Simplex or Quadratic promming. It refers to an “OOSOL library”, have you

explained this a little more in detail in any of your tutorial sections.

If not, then could you give me a reference which would help me understand

these option better?

thanks

prabhav.

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