In this simple model there are two muscles, the lower (muscle, -y direction) pulls a 1-kg ball against gravity and his force is correctly 9.81 N. The upper (ghost_muscle, +y direction) is simply attached to a fully constrained segment which has no mass. Its force (Ft) should be identically zero all time. However, its force is not negligible, being 0.001858616, which is way above numerical noise.
[li]switching off the reaction of ghost_driver makes the ghost_muscle force go to zero (= 3.679053e-038 numerical noise)[/li][li]changing muscle recruitment criterion type or polynomial exponent changes the output force of this muscle[/li][li]changing the mass of the ghost_segment has no effect on this[/li][li]switching off the gravity has no effect on this[/li][li]force direction of ghost_muscle has no effect[/li][/ul]
Is there a flaw in this model or is this a bug in the muscle recruitment solver?
Using AnyBody version : 7. 2. 0. 6089 (64-bit version) Build : 17590.43440 (beta)
Tried as well with AnyBody version : 7. 1. 2. 6044 (64-bit version) Build : 17695.40860