How to simulate sensor latency?

[Nate711]

Are there any mechanisms already implemented in Isaac Sim or Isaac Lab for simulating sensor latency? Or do we have to write our own buffer management? Thanks!

[RandomOakForest]

NVIDIA Isaac Sim and Isaac Lab provide built-in tools for simulating sensor latency through the DelayBuffer class in the isaaclab.utils.buffers module. This mechanism allows you to introduce configurable delays into sensor data streams without custom buffer management. Here's a summary of how it works:

Key Features of the DelayBuffer

• Time-lagged data retrieval: Stores sensor data in a batched circular buffer and retrieves it with user-defined delays¹².
• Per-batch configurability: Supports different delay settings for individual sensors or environments using batch indices¹.
• Automatic fallback: Returns the most recent data if the requested delay exceeds available history².

Example usage:

from isaaclab.utils import DelayBuffer

# Create buffer with 10-step history for 4 sensors
delay_buffer = DelayBuffer(history_length=10, batch_size=4, device="cuda")

# Set different delays per sensor
delay_buffer.set_time_lag(torch.tensor([2, 3, 1, 0]))

# Simulate sensor update loop
current_data = sensor.read()
delayed_data = delay_buffer.compute(current_data)

Implementation Details

The DelayBuffer uses a circular buffer architecture that:

1. Stores input data with configurable history length¹
2. Applies per-sensor delays using time_lags tensor²
3. Automatically handles buffer reset and device management¹

For specialized requirements, developers can extend this base class or combine it with Isaac Lab's sensor framework that supports:

• USD-based sensors: RTX cameras, LiDARs with native Omniverse integration³
• Custom sensors: Warp-based ray-casters and Python-implemented sensors³

When to Use Custom Solutions

While the DelayBuffer handles basic latency simulation, you might need custom implementations for:

• Hardware-specific synchronization protocols
• Complex multi-sensor temporal alignment
• Non-linear delay models

The built-in system provides foundation components that can be extended through Isaac Lab's modular sensor API³¹.

References

Footnotes

1. https://isaac-sim.github.io/IsaacLab/main/source/api/lab/isaaclab.utils.html ↩ ↩² ↩³ ↩⁴ ↩⁵

2. https://docs.robotsfan.com/isaaclab_official/v2.1.0/_modules/isaaclab/utils/buffers/delay_buffer.html ↩ ↩² ↩³

3. https://isaac-sim.github.io/IsaacLab/main/source/api/lab/isaaclab.sensors.html ↩ ↩² ↩³

[mindThomas]

This DelayBuffer just simulates pure lag through a circular buffer.
But how about cases where zero-order hold would be more appropriate, such as the case where you have a sensor that provides data at a lower rate than the current simulation step rate?
One example would be when dealing with sensors with different sample rates. Another example would be for slow observers or state estimators that takes time to compute for which the system has to rely on the previous state estimate for a predefined number of steps.