Specifications

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This appears to be equally good in terms of activity level and has the added quality of increasing muscle
activity or effort for increasing angle. This can make it easier for the operator to control the pedal and
thereby enhance the operability.
The completed model is available here: PedalDemo.zip
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The AnyBody Modeling System is all about making this type of investigation easy. The mechanical model we
have put together in four simple lessons has a complexity worthy of a Ph.D. project if you develop it bottom
up. In AnyBody, this is a matter of a few hours of work when using the predefined models of the repository.
Let's continue to Lesson 9: Model Structure.
Lesson 9: Model Structure
This section contains recommendations on construction of body parts to make them compatible with the
model structure of the AnyScript Repository
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Building an AnyScript model of a body part or the complete body is much like any other complex
construction work in the sense that it requires planning and coordination. This is particularly true if different
people divide the task between them and later assemble the model. These are the general
recommendations:
The Repository uses the ISB coordinate system.
The International Society of Biomechanics is endorsing the use of a particular convention for coordinate axes
in the human body, and so are we. These recommendations are published in these references:
Wu G, Cavanagh PR.: ISB recommendations for standardization in the reporting of kinematic data. J
Biomech 1995 Oct;28(10):1257-1261
Wu G, Siegler S, Allard P, Kirtley C, Leardini A, Rosenbaum D, Whittle M, D'Lima DD, Cristofolini L, Witte H,
Schmid O, Stokes I.: ISB recommendation on definitions of joint coordinate system of various joints for the
reporting of human joint motion-part I: ankle, hip, and spine. J Biomech 2002 Apr;35(4):543-548.
Conventions like these are always debatable. For instance, ISB recommends a vertical y axis, where many
users probably feel that a vertical z axis is natural But there is a distinct benefit to having a standard, so
most of the models in the repository adhere to the ISB recommendation.
The Repository uses SI Units
SI units are based on meters, kilograms and seconds. They are consistent and therefore eliminate the
possibility of miscalculations due to hidden conversion factors. For instance, a seemingly consistent use of
millimeters instead of meters in a model may lead to the devious error of square root 1000 in some types of
calculations. The AnyBody Modeling System expects all angles to be specified in radians. If you feel more
comfortable working with degrees you can use expressions to convert to radians like this example where we
specify an angle of 30 degrees:
AnyVar KneeAngle = 30*Pi/180;
Bodies and environments
When you load a model from the repository and investigate its tree, you will find that it is structured with
one folder for the body parts (HumanModel), one folder for the environment (EnnvironmentModel), and one
folder for the connection between the human model and the environment (ModelEnvironmentConnection).