Specifications

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//rDot0 = {0, 0, 0};
//Axes0 = {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}};
//omega0 = {0, 0, 0};
Mass = 0;
Jii = {0, 0, 0};
//Jij = {0, 0, 0};
//sCoM = {0, 0, 0};
};
}; // Segs folder
The object inserter has created a template of a segment for you. It contains all the properties you can set
for an AnySeg object. Some of them are active while other are commented out by two leading slashes. The
ones that are commented out are optional properties. You can set them if you like, but if you leave them out
they will retain the values already indicated in the inserted lines. If you do not plan on using them, you can
erase them. The object properties without leading slashes are those that must be set. This is the case for
Mass and Jii, for instance, which are respectively the mass of the segment and the diagonal elements of the
inertia tensor. In a system that simulates dynamics, all segments must have mass and inertia. The system
allows you to set them to zero, but it does not make sense not to set them at all.
More formally, object properties are divided into three different groups:
• Obligatory. Like Mass and Jii, these must be set by the user when the object is defined
• Access denied. These are computed automatically by the system and cannot be specified by the
user.
• Optional. These can be set by the user or left to their default values.
You can find a complete description of all possible properties of all objects in the reference manual
.
Let us give the new segment the name UpperArm and set its Mass = 2 and also assign reasonable values
for Jii:
AnySeg UpperArm = {
//r0 = {0, 0, 0};
//Axes0 = {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}};
Mass = 2;
Jii = {0.001, 0.01, 0.01};
}; //UpperArm
Click again (or press F7). Among the messages you get are:
Model Warning: Study 'Main.ArmStudy' contains too few kinematic constraints to be
kinematically determinate.
Don't worry about it just now. It only means that you are not finished with the necessary elements to do an
actual analysis yet.
Now that we have a physical object in the model, let's see what it looks like. To make something visible in
AnyBody, you have to add a line that defines visibility:
AnySeg UpperArm = {
//r0 = {0, 0, 0};
//Axes0 = {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}};
Mass = 2;
Jii = {0.001, 0.01, 0.01};
AnyDrawSeg drw = {};
}; // UpperArm