Like motion sources, initial conditions can cause motion conflicts. Unlike motion sources, they do not impose constraints or remove DoFs from the driveline, because they act only at the start of the simulation. However, under certain circumstances, initial conditions can cause errors when you start the simulation:
Initial conditions conflict with one another.
Example: You couple two driveline axes through a Gear with a gear ratio of 2. The base axis must spin twice as fast as the follower, in the same direction. If you actuate the base with a velocity source, and the follower is connected to an inertia with initial velocity not set to half the initial base velocity, the simulation stops with an error.
Initial conditions conflict with motion sources. When the simulation starts, the signal controlling a velocity source acting on an axis and the initial velocity value specified on an Inertia or a Mass attached to that axis must agree. Analogous requirements hold for velocities transformed by gear couplings.
Regardless of how you set the initial conditions of your driveline axes, the complete set of initial conditions must be consistent with itself. Driveline connection lines satisfying angular velocity constraints (for example, branched lines, or lines in closed loops) must have the same initial angular velocities.