Physics Backends

Isaac Lab 3.0 supports multiple physics backends through a unified API. Each backend exposes the same Articulation, RigidObject, sensor and renderer surfaces, while differing in solver characteristics, maturity, and feature coverage. See Multi-Backend Architecture for how the dispatch and factory machinery work under the hood.

This page summarizes what each backend supports today; the sub-pages document backend-specific configuration, installation, and limitations.

• PhysX Backend
  • Installation
  • PhysX Configuration
  • Supported Features
• Newton Backend
  • Installation
  • Supported Features
  • MJWarp Solver
  • Kamino Solver
  • Using the VBD Solver
  • Newton Manager Abstraction
  • Warp Experimental Environments
  • Warp Environment Migration Guide
• OvPhysX Backend
  • Why use OvPhysX?
  • What works today
  • Status and follow-up
• Solver Comparison
  • Friction Model
  • Contact Detection and Resolution
  • Restitution and Bounce
  • Constraint Stabilization
  • Solver Convergence
  • Articulation Coordinates
  • Substepping and Timestep
  • GPU Buffers and Throughput
  • Porting Checklist

Choosing a Backend

• PhysX — the historical default. Production-ready, broad coverage of Isaac Lab features, and the reference for behavior parity. Selected via PhysxCfg.

• Newton — GPU-accelerated, Warp-native, and differentiable. The Newton integration ships with the MuJoCo-Warp solver and beta support for the Kamino solver. Selected via NewtonCfg.

• OvPhysX — a highly experimental kit-less PhysX backend that reads scene-level parameters from the USD PhysicsScene prim. Selected via OvPhysxCfg. Not recommended for general use yet.

The active backend is selected at simulation construction time and applies to every asset, sensor, and renderer instantiated thereafter:

from isaaclab.sim import SimulationCfg
from isaaclab_physx.physics import PhysxCfg
from isaaclab_newton.physics import NewtonCfg, MJWarpSolverCfg

# PhysX (default)
sim_cfg = SimulationCfg(physics=PhysxCfg())

# Newton with MuJoCo-Warp
sim_cfg = SimulationCfg(physics=NewtonCfg(solver_cfg=MJWarpSolverCfg()))

Feature Support Matrix

The matrix below is intentionally coarse-grained. For exhaustive per-asset and per-task support, see each backend’s own limitations page.

Feature	PhysX	Newton	OvPhysX
Maturity	Stable	Beta	Highly experimental
Default solver	TGS (rigid body)	MuJoCo-Warp	PhysX (TGS / PGS via USD)
Alternative solvers	PGS	Kamino (beta), additional Newton solvers planned	—
Differentiable	No	Yes (via Warp)	No
Articulation API	Yes	Yes	In-flight (PR #5459)
Rigid Object API	Yes	Yes	Yes
Contact Sensor	Yes	Yes	In-flight (PR #5422)
IMU	Yes	Yes	In-flight (PR #5421)
Frame Transformer / Ray Caster / PVA / Joint-Wrench Sensor	Yes	Yes	Not yet
Camera / Tiled Rendering	Yes (RTX)	Yes (Newton-Warp renderer)	Not yet
Requires Isaac Sim	Yes	Optional (only for the Omniverse visualizer)	Yes
Solver configuration source	PhysxCfg	NewtonCfg + solver config	USD PhysicsScene + OvPhysxCfg

Selecting Backends per Task

Tasks that support more than one backend define a Hydra preset on SimulationCfg.physics. The example below shows the cartpole task config which declares all three backends side by side:

from isaaclab_physx.physics import PhysxCfg
from isaaclab_newton.physics import MJWarpSolverCfg, NewtonCfg
from isaaclab_ovphysx.physics import OvPhysxCfg

@configclass
class CartpolePhysicsCfg(PresetCfg):
    default: PhysxCfg = PhysxCfg()
    physx: PhysxCfg = PhysxCfg()
    newton_mjwarp: NewtonCfg = NewtonCfg(solver_cfg=MJWarpSolverCfg())
    ovphysx: OvPhysxCfg = OvPhysxCfg()

Users then select the backend at the command line via presets=<name> or by overriding the physics field directly. See Backend and Solver Presets for the full Hydra interaction.