hc825b / reproduce

Experiments with Reruning under Uncertainty in Initial States

Motivation

To examine the changes in behavior when running the simulator with small uncertainty in initial states

Procedures to minimize other uncertainties

• Nondeterministic order in launching

  • Launch all ROS nodes with simulated time paused in the initialization phase.

• Randomness in simulator

  • Set a predefined random seed for Gazebo using --seed option

• Jitter

  • Slowdown the simulation physics profile to ensure that the wall time of each cycle is much larger than the jitter. Equivalently, the jitter in simulated time is reduced.

• Communication delay to the recorder node

  • Set TCP_NODELAY for rosbag record
  • Alternatively, use stamped values as messages. The timestamp is from the sender; hence to minimize clock skew, we run the whole simulation on the same computer.