All,
One of the options is to declare them as ports in the module statement and then I can visualize position and velocity nodes. But the question remains ...if not declared as a port, how do i save/plot an internal kinematic value?
TIA,
Best,
/d

As Ken says, copying the value to a variable is the most likely solution. My impression is that internal nodes, even electrical ones, are not available for plotting in most simulators.
A number of simulators support the attributes in VAMS LRM 2.2 for declaring "operating point values" (some will give you all the variables when you "save all" but only give you the op-pt variables if you've declared at least one). The way to do this is to use the "desc" and/or "units" attributes:

(* desc="position", units="m" *) real z_pos;

Do this outside the analog block, eg right after
real A, b, C, C ...

Then, inside the analog block,
   z_pos = Pos(z);

There's no ADE limitation regarding non-electrical signals. The issue is that Spectre does not save them if you have save=selected or save=allpub (in ADE on Outputs->Save All). If you change it to save=all (not allpub), you can then plot these internal signals with no problem (albeit via the results browser). They will even be plotted with the right units on the graph...

If you really don't want to save "all" signals, you can workaround the fact that there's no ADE way of referencing internal signals by using Outputs->Save All, go to the "Save by Subckt" tab, and entering the instance name of the RF_MEMS_CAPACTOR (e.g /I0) - then in the rightmost column where it says User Options type the spectre hierarchical name you wish to to save, e.g. I0.z (so this will be using dot as the hierarchy separator, not /). Bit clunky, and there ought to be an easier way, but better than nothing.

Andrew.