This class is autogenerated. More detailed documentation can be found in the SDFormat spec.

class v18.physics.Physics.Simbody(min_step_size=0.0001, accuracy=0.001, max_transient_velocity=0.01, contact=None)

Simbody specific physics properties.

min_step_size: (Currently not used in simbody) The time duration

which advances with each iteration of the dynamics engine, this has to be no bigger than max_step_size under physics block. If left unspecified, min_step_size defaults to max_step_size.

accuracy: Roughly the relative error of the system.

-LOG(accuracy) is roughly the number of significant digits.

max_transient_velocity: Tolerable “slip” velocity allowed by the

solver when static friction is supposed to hold object in place.

contact: Relationship among dissipation, coef. restitution, etc.

d = dissipation coefficient (1/velocity) vc = capture velocity (velocity where e=e_max) vp = plastic velocity (smallest v where e=e_min) > vc Assume real COR=1 when v=0. e_min = given minimum COR, at v >= vp (a.k.a. plastic_coef_restitution) d = slope = (1-e_min)/vp OR, e_min = 1 - d*vp e_max = maximum COR = 1-d*vc, reached at v=vc e = 0, v <= vc = 1 - d*v, vc < v < vp = e_min, v >= vp dissipation factor = d*min(v,vp) [compliant] cor = e [rigid] Combining rule e = 0, e1==e2==0 = 2*e1*e2/(e1+e2), otherwise

Nested Elements

Note that only complex elements are listed here. Elements that resolve to simple types (int, str, bool) are inlined.


Relationship among dissipation, coef.