PhysX Backend#
NVIDIA PhysX is the historical default physics backend in Isaac Lab. It runs through NVIDIA Isaac Sim’s Omniverse Kit runtime and supports GPU-accelerated rigid-body, articulation, soft-body, and particle simulation. PhysX is the reference backend for behaviour parity in Isaac Lab — assets, sensors, and tasks have all been validated against it first, and the other backends are measured against PhysX behaviour.
PhysX is selected via PhysxCfg:
from isaaclab.sim import SimulationCfg
from isaaclab_physx.physics import PhysxCfg
sim_cfg = SimulationCfg(physics=PhysxCfg())
The PhysX backend uses the Temporal Gauss-Seidel (TGS) solver by default and also
exposes a Projective Gauss-Seidel (PGS) variant. Scene-level solver tuning, GPU
buffer sizing, and contact-handling parameters live on
PhysxCfg; per-actor settings remain on the USD
schema. See PhysX Configuration for the most common knobs.
For an overview of how the multi-backend architecture works, see Multi-Backend Architecture.