AMCL

Source code on Github.

AMCL implements the server for taking a static map and localizing the robot within it using an Adaptive Monte-Carlo Localizer.

Parameters

`alpha1`

Type: double Default: 0.2: Expected process noise in odometry's rotation estimate from rotation.

`alpha2`

Type: double Default: 0.2: Expected process noise in odometry's rotation estimate from translation.

`alpha3`

Type: double Default: 0.2: Expected process noise in odometry's translation estimate from translation.

`alpha4`

Type: double Default: 0.2: Expected process noise in odometry's translation estimate from rotation.

`alpha5`

Type: double Default: 0.2: For Omni models only: translation noise.

`base_frame_id`

Type: string Default: "base_footprint": Robot base frame.

`beam_skip_distance`

Type: double Default: 0.5: Ignore beams that most particles disagree with in Likelihood field model. Maximum distance to consider skipping for (m).

`beam_skip_error_threshold`

Type: double Default: 0.9: Percentage of beams after not matching map to force full update due to bad convergence.

`beam_skip_threshold`

Type: double Default: 0.3: Percentage of beams required to skip.

`do_beamskip`

Type: bool Default: false: Whether to do beam skipping in Likelihood field model.

`global_frame_id`

Type: string Default: "map": The name of the coordinate frame published by the localization system.

`lambda_short`

Type: double Default: 0.1: Exponential decay parameter for z_short part of model.

`laser_likelihood_max_dist`

Type: double Default: 2.0: Maximum distance to do obstacle inflation on map, for use in "likelihood_field" model.

`laser_max_range`

Type: double Default: 100.0: Maximum scan range to be considered, -1.0 will cause the laser's reported maximum range to be used.

`laser_min_range`

Type: double Default: -1.0: Minimum scan range to be considered, -1.0 will cause the laser's reported minimum range to be used.

`laser_model_type`

Type: string Default: "likelihood_field": Which model to use, either "beam", "likelihood_field", or "likelihood_field_prob". Same as "likelihood_field" but incorporates the beamskip feature, if enabled.

`set_initial_pose`

Type: bool Default: false: Causes AMCL to set initial pose from the initial_pose* parameters instead of waiting for the initial_pose message.

`initial_pose`

Type: Pose2D Default: {x: 0.0, y: 0.0, z: 0.0, yaw: 0.0}: X, Y, Z, and yaw coordinates of initial pose (meters and radians) of robot base frame in global frame.

`max_beams`

Type: int Default: 60: How many evenly-spaced beams in each scan to be used when updating the filter.

`max_particles`

Type: int Default: 2000: Maximum allowed number of particles.

`min_particles`

Type: int Default: 500: Minimum allowed number of particles.

`odom_frame_id`

Type: string Default: "odom": Which frame to use for odometry.

`pf_err`

Type: double Default: 0.05: Particle Filter population error.

`pf_z`

Type: double Default: 0.99: Particle filter population density. 2.33 is the 99% percentile.

`random_seed`

Type: int Default: -1

Seed for the particle filter RNG.

random_seed >= 0: seed the RNG with the provided value (repeatable runs).
random_seed < 0 (default): seed the RNG from time (preserves historical behavior).

`recovery_alpha_fast`

Type: double Default: 0.0: Exponential decay rate for the fast average weight filter, used in deciding when to recover by adding random poses. A good value might be 0.1.

`recovery_alpha_slow`

Type: double Default: 0.0: Exponential decay rate for the slow average weight filter, used in deciding when to recover by adding random poses. A good value might be 0.001.

`resample_interval`

Type: int Default: 1: Number of filter updates required before resampling.

`robot_model_type`

Type: string Default: "nav2_amcl::DifferentialMotionModel": The fully-qualified type of the plugin class. Options are "nav2_amcl::DifferentialMotionModel" and "nav2_amcl::OmniMotionModel". Users can also provide their own custom motion model plugin type.

`save_pose_rate`

Type: double Default: 0.5: Maximum rate (Hz) at which to store the last estimated pose and covariance to the parameter server, in the variables ~initial_pose_* and ~initial_cov_*. This saved pose will be used on subsequent runs to initialize the filter (-1.0 to disable).

`sigma_hit`

Type: double Default: 0.2: Standard deviation for Gaussian model used in z_hit part of the model.

`tf_broadcast`

Type: bool Default: true: Set this to false to prevent amcl from publishing the transform between the global frame and the odometry frame.

`transform_tolerance`

Type: double Default: 1.0: Time with which to post-date the transform that is published, to indicate that this transform is valid into the future.

`introspection_mode`

Type: string Default: "disabled": The introspection mode for services and actions. Options are "disabled", "metadata", "contents".

`update_min_a`

Type: double Default: 0.2: Rotational movement required before performing a filter update.

`update_min_d`

Type: double Default: 0.25: Translational movement required before performing a filter update.

`z_hit`

Type: double Default: 0.5: Mixture weight for z_hit part of model, sum of all used z weight must be 1. Beam uses all 4, likelihood model uses z_hit and z_rand.

`z_max`

Type: double Default: 0.05: Mixture weight for z_max part of model, sum of all used z weight must be 1. Beam uses all 4, likelihood model uses z_hit and z_rand.

`z_rand`

Type: double Default: 0.5: Mixture weight for z_rand part of model, sum of all used z weight must be 1. Beam uses all 4, likelihood model uses z_hit and z_rand.

`z_short`

Type: double Default: 0.005: Mixture weight for z_short part of model, sum of all used z weight must be 1. Beam uses all 4, likelihood model uses z_hit and z_rand.

`always_reset_initial_pose`

Type: bool Default: false: Requires that AMCL is provided an initial pose either via topic or initial_pose* parameter (with parameter set_initial_pose: true) when reset. Otherwise, by default AMCL will use the last known pose to initialize.

`scan_topic`

Type: string Default: "scan": Laser scan topic to subscribe to.

`map_topic`

Type: string Default: "map": Map topic to subscribe to.

`first_map_only`

Type: bool Default: false: Allows AMCL to accept maps more than once on the map_topic. This is especially useful when you're using the LoadMap service in map_server.

`bond_heartbeat_period`

Type: double Default: 0.25: The lifecycle node bond mechanism publishing period (on the /bond topic). Disabled if inferior or equal to 0.0.

`allow_parameter_qos_overrides`

Type: bool Default: true: Whether to allow QoS profiles to be overwritten with parameterized values.

Example

amcl:
  ros__parameters:
    alpha1: 0.2
    alpha2: 0.2
    alpha3: 0.2
    alpha4: 0.2
    alpha5: 0.2
    base_frame_id: "base_footprint"
    introspection_mode: "disabled"
    beam_skip_distance: 0.5
    beam_skip_error_threshold: 0.9
    beam_skip_threshold: 0.3
    do_beamskip: false
    global_frame_id: "map"
    lambda_short: 0.1
    laser_likelihood_max_dist: 2.0
    laser_max_range: 100.0
    laser_min_range: -1.0
    laser_model_type: "likelihood_field"
    max_beams: 60
    max_particles: 2000
    min_particles: 500
    odom_frame_id: "odom"
    pf_err: 0.05
    pf_z: 0.99
    random_seed: -1
    recovery_alpha_fast: 0.0
    recovery_alpha_slow: 0.0
    resample_interval: 1
    robot_model_type: "nav2_amcl::DifferentialMotionModel"
    save_pose_rate: 0.5
    sigma_hit: 0.2
    tf_broadcast: true
    transform_tolerance: 1.0
    update_min_a: 0.2
    update_min_d: 0.25
    z_hit: 0.5
    z_max: 0.05
    z_rand: 0.5
    z_short: 0.05
    scan_topic: scan
    map_topic: map
    set_initial_pose: false
    always_reset_initial_pose: false
    first_map_only: false
    initial_pose:
      x: 0.0
      y: 0.0
      z: 0.0
      yaw: 0.0