Would you please consider the following questions about the attributes of floating objects given in the XML guide
(version April 2019, section 2.6)?
These attributes can be computed by GenCase or be custom-defined in the code. In order to specify the values correctly, I would need to know more about their definitions.
The attribute center
is defined as the 'gravity center of the rigid object'.
- Q1: Is this the 'centre of mass'? I presume so, this is just about matching terminologies.
- Q2: Which reference system should the coordinates be given in? The global one (the domain, as from inside definition) or the local one (the object, as from inside a setmkbound for example)?
- Q3: Reformulation of Q2. Say that I draw an object after rotating the global reference system (rotate x=...), and do not revert to the original system (no matrixreset) before moving on to the floatings specifications. Will the coordinates of "center" live in the original or in the modified reference system?
- Q4: Linked to Q1. Does the code takes into account eccentricity when the centre of mass is not the centroid of the figure?
The attribute inertia
is defined as 'momentum of inertia of the rigid object'. There is a slip of the pen since it should be 'moment of inertia'.
- Q5: With respect to which axes are these moments of inertia?
- Q6: Is the code informed about the principal moments of inertia of objects with a predefined shape such as drawbox, drawsphere?
- Q7: Similar to Q3. If the object I drew is no longer aligned with the global reference system, which axes are considered for the moments of inertia?
Although I anticipate that the Project Chrono implementation clarifies these question, coding the old way may still be attractive for simple enough cases. So, in your answers, references to what the basic code does do and to what it does not do are equally valued.
Thanks in advance for dealing with this.