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Version: 1.5.0

Run Simulation Faster than Real-time

Simulation In The Loop (SITL) can be run faster or slower than real-time.

The speed factor is set using the environment variable PX4_SIM_SPEED_FACTOR. For example, to run the simulation at 2 times the real-time speed put the following command to your session.yml into pre_window part, or into ~/.bashrc:

export PX4_SIM_SPEED_FACTOR=2

To run at half real-time:

export PX4_SIM_SPEED_FACTOR=0.5

Example of setting session.yml with PX4_SIM_SPEED_FACTOR=2​

name: simulation
root: ./
startup_window: status
pre_window: export UAV_NAME=uav1; export RUN_TYPE=simulation; export UAV_TYPE=t650; export WORLD_NAME=simulation; export PX4_SIM_SPEED_FACTOR=2
windows:
...

For more detail description see px4 website.

Run Simulation SLOWER than Real-time

Running simulation slower using the PX4_SIM_SPEED_FACTOR variable causes problems when simulating multiple UAVs. To slow down the simulation instead change the max real-time update rate of Gazebo some time after the start of the simulation, i.e., include this in your session.yml file to slow down the simulation to 0.5 real-time factor:

  - gz_rate:
      layout: tiled
      panes:
        - waitForOdometry; sleep 5; gz physics -u 125

gz physics -u 250 corresponds to real-time factor 1.0, reduce the update rate accordingly to reach your desired real-time factor.