Hi Sherm, thanks for your reply. The documentation states that calcSystemJacobian() returns a mapping from generalized speeds to the spatial velocities of all the bodies. In contrast, the modal analysis requires the derivatives of the system equations of motion with respect to the generalized coordi...

Hi,

the 'Simbody Theory Manual' mentions that modal analyses could be performed using the dynamic, internal coordinate Jacobian. Is this actually possible with the current Simbody version?

Thank you!
Simon

Hi Sherm,

thank you for the prompt reply. I will modify my model to avoid the singularity.

Regards,
Simon

Hi, is it possible to enforce constraints between parts if one side of the constraint is massless? An example would be one massless pendulum in 'ExampleCustomConstraint.cpp', which results in 'nan's on my machine. I suppose that this fails because the constraint forces need some non-zero inertia ele...