newton.solvers

Solvers are used to integrate the dynamics of a Newton model. The typical workflow is to construct a Model and a State object, then use a solver to advance the state forward in time via the step() method:

        ---
config:
  theme: forest
  themeVariables:
    lineColor: '#76b900'

---
flowchart LR
    subgraph Input["Input Data"]
        M[newton.Model]
        S[newton.State]
        C[newton.Control]
        K[newton.Contacts]
        DT[Time step dt]
    end

    STEP["solver.step()"]

    subgraph Output["Output Data"]
        SO["newton.State (updated)"]
    end

    %% Connections
    M --> STEP
    S --> STEP
    C --> STEP
    K --> STEP
    DT --> STEP
    STEP --> SO
    

Supported Features

Solver	Integration	Rigid bodies	Articulations	Particles	Cloth	Soft bodies
SolverFeatherstone	Explicit	✅	✅ generalized coordinates	✅	🟨 no self-collision	✅
SolverImplicitMPM	Implicit	❌	❌	✅	❌	❌
SolverMuJoCo	Explicit, Semi-implicit, Implicit	✅ (uses its own collision pipeline from MuJoCo/mujoco_warp by default, unless use_mujoco_contacts is set to False)	✅ generalized coordinates	❌	❌	❌
SolverSemiImplicit	Semi-implicit	✅	✅ maximal coordinates	✅	🟨 no self-collision	✅
SolverStyle3D	Implicit	❌	❌	✅	✅	❌
SolverVBD	Implicit	❌	❌	✅	✅	❌
SolverXPBD	Implicit	✅	✅ maximal coordinates	✅	🟨 no self-collision	🟨 experimental

Classes

SolverBase	Generic base class for solvers.
SolverFeatherstone	A semi-implicit integrator using symplectic Euler that operates on reduced (also called generalized) coordinates to simulate articulated rigid body dynamics based on Featherstone's composite rigid body algorithm (CRBA).
SolverImplicitMPM	Implicit MPM solver.
SolverMuJoCo	This solver provides an interface to simulate physics using the MuJoCo physics engine, optimized with GPU acceleration through mujoco_warp.
SolverNotifyFlags	Flags indicating which parts of the model have been updated and require the solver to be notified.
SolverSemiImplicit	A semi-implicit integrator using symplectic Euler.
SolverStyle3D	Projective dynamic based cloth simulator.
SolverVBD	An implicit solver using Vertex Block Descent (VBD) for cloth simulation.
SolverXPBD	An implicit integrator using eXtended Position-Based Dynamics (XPBD) for rigid and soft body simulation.