Loopback Simulator

Source code on Github.

The nav2_loopback_sim is a stand-alone simulator to create a "loopback" for non-physical simulation to replace robot hardware, physics simulators (Gazebo, Bullet, Isaac Sim, etc). It computes the robot's odometry based on the command velocity's output request to create a perfect 'frictionless plane'-style simulation for unit testing, system testing, R&D on higher level systems, testing behaviors without concerning yourself with localization accuracy or system dynamics, and multirobot simulations.

Parameters

`update_duration`

Type: double Default: 0.01: The duration between updates (s)

`base_frame_id`

Type: string Default: "base_footprint": The base frame to use.

`odom_frame_id`

Type: string Default: "odom": The odom frame to use.

`map_frame_id`

Type: string Default: "map": The map frame to use.

`scan_frame_id`

Type: string Default: "base_scan": The scan frame to use to publish a scan

`enable_stamped_cmd_vel`

Type: bool Default: true: Whether cmd_vel is stamped or unstamped (i.e. Twist or TwistStamped).

`scan_publish_dur`

Type: double Default: 0.1: The duration between publishing scan (in sec)

`odom_publish_dur`

Type: double Default: <update_duration>: The duration between publishing odometry (in sec). Defaults to update_duration.

`publish_map_odom_tf`

Type: bool Default: true: Whether or not to publish tf from map_frame_id to odom_frame_id

`publish_scan`

Type: bool Default: true: Whether or not to publish a fake laser scan.

`publish_clock`

Type: bool Default: true: Whether or not to publish simulated clock to /clock

`speed_factor`

Type: double Default: 1.0: Speed factor for the simulated clock, e.g. 2.0 runs simulation at 2x wall time. Only used when publish_clock is true. Dynamically reconfigurable.

`scan_range_min`

Type: double Default: 0.05: Minimum measurable distance from the scan in meters. Values below this are considered invalid.

`scan_range_max`

Type: double Default: 30.0: Maximum measurable distance from the scan in meters. Values beyond this are out of range.

`scan_angle_min`

Type: double Default: -3.14: Starting angle of the scan in radians (leftmost angle)

`scan_angle_max`

Type: double Default: 3.14: Ending angle of the scan in radians (rightmost angle)

`scan_angle_increment`

Type: double Default: 0.0261: Angular resolution of the scan in radians (angle between consecutive measurements)

`scan_use_inf`

Type: bool Default: true: Whether to use inf for out-of-range values. If false, values are set to scan_range_max - 0.1 instead.

`scan_noise_std`

Type: double Default: 0.01: Standard deviation of Gaussian noise added to scan ranges (in meters).

Example

loopback_simulator:
  ros__parameters:
    base_frame_id: "base_footprint"
    odom_frame_id: "odom"
    map_frame_id: "map"
    scan_frame_id: "base_scan"  # tb4_loopback_simulator.launch.py remaps to 'rplidar_link'
    update_duration: 0.02
    publish_scan: true
    publish_clock: true
    speed_factor: 1.0
    scan_range_min: 0.05
    scan_range_max: 30.0
    scan_angle_min: -3.1415
    scan_angle_max: 3.1415
    scan_angle_increment: 0.02617
    scan_use_inf: true
    scan_noise_std: 0.01