In file /home/blah/darwin2k/src/dyno/mechanism/dynoSvals.h:

class svAtom

The base class for s-vals.

Inheritance:


Public Fields

[more]int n
number of elements in the s-vals; equal to system DOFs + 1


Documentation

The base class for s-vals. S-vals, short for "separated values", are a simple symbolic representation for dynamic equations. You will most likely be using s-vals when creating new joint or constraint types; otherwise, you can ignore them.

One of the key steps in dynamic simulation is to compute the acceleration of a mechanism's degrees of freedom. To do this, the equations can be organized in the form:

   T = M*acc + V
 
where T is a torque vector for the mechanism's degrees of freedom, M is a symmetric positive definite mass matrix for the mechanism, acc is the vector of accelerations for each degree of freedom, and V is a vector containing all terms that do not depend on joint accelerations. s-vals allow M and V to be computed by keeping the multipliers for each DOF acceleration variable separate. Put another way, an s-val is a linear combination of joint acceleration variables plus a constant term. The important things to keep in mind are: In practice, you only need to worry about the first of these two points since the latter is taken care of by dyno. As mentioned earlier, you will normally not need to know anything about s-vals unless you're creating new joint or constraint types. For the case of joints, you need to create an equation (using s-vals) that describes the torque required to cause a given acceleration of the joint. For constraints, you need to create an equation that describes the acceleration of the constraint as a function of the mechanism's joint accelerations. It's best to look at joint::createEquations() and constraint::createConstraintEquations() for examples of s-val use. There are, however, some important rules for s-val equations that should be mentioned here:

There are a number of arithmetic operators overloaded for s-vals; they are defined in dynoSvOps.h.

oint n
number of elements in the s-vals; equal to system DOFs + 1


Direct child classes:
svTriple
svScalar
Friends:
svTripleResult

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