isaac-sim-robot-navigation

Development

Runtime robot navigation in NVIDIA Isaac Sim — driving a robot through a scene live in a custom script. Covers RL policy loading (PolicyController), trajectory following, physics-vs-baked-vs-per-frame approaches for heavy stages, GPU OOM avoidance on 98K-prim scenes, Kit 110-specific timeline/physics gotchas, and standard Spot route catalog. For occupancy maps, A*, kinematics, and camera math, see `navigation-primitives`. For sensor-recording SDG, see `mobility-gen`. Use when navigating a robot live in your own Isaac Sim script, choosing between physics simulation and pre-baked transforms for heavy stages, debugging GPU OOM on large scenes, or troubleshooting Kit 110 physics hangs after kill+relaunch. Triggers on: PolicyController, RL policy load, trajectory follow, baked vs physics, per-frame transform, GPU OOM navigation, Kit 110 timeline.play, robot navigation runtime.

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Isaac Sim Robot Navigation — Runtime

Runtime navigation specialization. Driving a robot through a USD scene live, in your own Isaac Sim script.

Read These Skills First

navigation-primitives — occupancy maps, A* planning, differential/holonomic kinematics, robot footprints (Spot Z=0.69, etc.), look-at chase camera math, common gotchas. This skill assumes you know that substrate.
isaac-sim-rendering — RT2, persistent session, ACES, frame validation
isaac-sim-troubleshooting — Kit 110 hang/freeze reference

When To Use This Skill (vs siblings)

Goal	Use
Drive a robot through a scene in real time, see it move	this skill
Record trajectories then re-render with sensors for SDG	`mobility-gen`
Publish/subscribe Nav2 topics to ROS 2	`isaac-sim-ros2-bridge`

Runtime APIs

Capability	API
RL policy execution	`isaacsim.robot.policy.examples.controllers.PolicyController`
Robot articulation	`isaacsim.core.experimental.prims.Articulation`
Physics lifecycle	`isaacsim.core.simulation_manager.SimulationManager`

For shared primitives (omap, A*, kinematics, look-at), see navigation-primitives.

Physics Simulation on Kit 110 (CRITICAL)

Timeline MUST be playing for Physics simulation

import omni.timeline
timeline = omni.timeline.get_timeline_interface()
timeline.play()  # WITHOUT THIS, PHYSICS NEVER STEPS

Strip non-robot physics from heavy stages

On 33K+ prim stages with multiple physic bodies, simulation hangs. Strip ALL physics from non-robot prims:

from pxr import Usd, UsdPhysics

for p in Usd.PrimRange(stage.GetPseudoRoot()):
    if str(p.GetPath()).startswith("/World/Robot"):
        continue
    if p.HasAPI(UsdPhysics.RigidBodyAPI):
        p.RemoveAPI(UsdPhysics.RigidBodyAPI)
    if p.HasAPI(UsdPhysics.CollisionAPI):
        p.RemoveAPI(UsdPhysics.CollisionAPI)

Kit 110 Exec Model (CRITICAL — 2026-03-15)

Synchronous code executes immediately in --exec scripts. No async needed for scene setup.

asyncio.ensure_future() needs explicit event loop subscription:

omni.kit.app.get_app().get_update_event_stream().create_subscription_to_pop(lambda e: None)
asyncio.ensure_future(main())

capture_viewport_to_file() returns MultiAOVFileCapture — use .wait_for_result(completion_frames=8), NOT .wait().
Pattern: sync scene build → async render scheduling → event loop keeps it alive
Scene load + 100 asset placement + 3-camera render in ~40s total

Camera Chase Cam

The look-at math and standard camera offsets (chase/overhead/POV) live in navigation-primitives. Runtime considerations on top of that:

Camera collision avoidance (TODO): chase camera clips into rack geometry when robot enters narrow aisles. Need raycast from chase eye → robot; if occluded, raise camera or shift laterally. Not yet implemented.

Failure Modes & Recovery

FAILURE: VkResult: ERROR_OUT_OF_DEVICE_MEMORY during navigation render

SYMPTOMS: Vulkan crash partway through capture loop on heavy stage
CAUSE: Approach B (baked timeSamples) + RT2 + 50K+ prims
FIX: Switch to approach C (per-frame transform)

FAILURE: Robot floats above ground or falls through floor

CAUSE: Wrong Z offset
FIX: See navigation-primitives Robot Footprint table

FAILURE: Physics never steps after kill+relaunch

CAUSE: Kill+relaunch bug, dirty GPU state
FIX: Wait 30+ seconds, verify zero Kit processes, or reboot

FAILURE: A* path looks fine on omap but robot clips a rack at render

CAUSE: Skipped step 5/6 of the validation pipeline (see navigation-primitives)
FIX: Always validate every smoothed point is in navigable space

Integration Points

RECEIVES from: navigation-primitives — omap, A*, kinematics, robot specs, camera math
RECEIVES from: occupancy-map — map.yaml or runtime grid
RECEIVES from: urdf-mjcf-to-usd-conversion — robot USD
PRODUCES for: isaac-sim-rendering — animated scene ready for RT2 capture and frame sequences of nav runs