newton.solvers.SemiImplicitSolver#

class newton.solvers.SemiImplicitSolver(model, angular_damping=0.05, friction_smoothing=1.0, joint_attach_ke=1.0e4, joint_attach_kd=1.0e2)[source]#

Bases: SolverBase

A semi-implicit integrator using symplectic Euler

After constructing Model and State objects this time-integrator may be used to advance the simulation state forward in time.

Semi-implicit time integration is a variational integrator that preserves energy, however it not unconditionally stable, and requires a time-step small enough to support the required stiffness and damping forces.

See: https://en.wikipedia.org/wiki/Semi-implicit_Euler_method

Example

solver = newton.solvers.SemiImplicitSolver(model)

# simulation loop
for i in range(100):
    solver.step(state_in, state_out, control, contacts, dt)
    state_in, state_out = state_out, state_in
__init__(model, angular_damping=0.05, friction_smoothing=1.0, joint_attach_ke=1.0e4, joint_attach_kd=1.0e2)#

Create a new Euler solver.

Parameters:

  • model (Model) – Model to use by this solver.

  • angular_damping (float, optional) – Angular damping factor to be used in rigid body integration. Defaults to 0.05.

  • friction_smoothing (float, optional) – Huber norm delta used for friction velocity normalization (see warp.math.norm_huber()). Defaults to 1.0.

  • joint_attach_ke (float, optional) – Joint attachment spring stiffness. Defaults to 1.0e4.

  • joint_attach_kd (float, optional) – Joint attachment spring damping. Defaults to 1.0e2.

step(state_in, state_out, control, contacts, dt)#