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
Default
double
0.2
- Description
Expected process noise in odometry’s rotation estimate from rotation.
- alpha2:
Type
Default
double
0.2
- Description
Expected process noise in odometry’s rotation estimate from translation.
- alpha3:
Type
Default
double
0.2
- Description
Expected process noise in odometry’s translation estimate from translation.
- alpha4:
Type
Default
double
0.2
- Description
Expected process noise in odometry’s translation estimate from rotation.
- alpha5:
Type
Default
double
0.2
- Description
For Omni models only: translation noise.
- base_frame_id:
Type
Default
string
“base_footprint”
- Description
Robot base frame.
- beam_skip_distance:
Type
Default
double
0.5
- Description
Ignore beams that most particles disagree with in Likelihood field model. Maximum distance to consider skipping for (m).
- beam_skip_error_threshold:
Type
Default
double
0.9
- Description
Percentage of beams after not matching map to force full update due to bad convergence.
- beam_skip_threshold:
Type
Default
double
0.3
- Description
Percentage of beams required to skip.
- do_beamskip:
Type
Default
bool
False
- Description
Whether to do beam skipping in Likelihood field model.
- global_frame_id:
Type
Default
string
“map”
- Description
The name of the coordinate frame published by the localization system.
- lambda_short:
Type
Default
double
0.1
- Description
Exponential decay parameter for z_short part of model.
- laser_likelihood_max_dist:
Type
Default
double
2.0
- Description
Maximum distance to do obstacle inflation on map, for use in likelihood_field model.
- laser_max_range:
Type
Default
double
100.0
- Description
Maximum scan range to be considered, -1.0 will cause the laser’s reported maximum range to be used.
- laser_min_range:
Type
Default
double
-1.0
- Description
Minimum scan range to be considered, -1.0 will cause the laser’s reported minimum range to be used.
- laser_model_type:
Type
Default
string
“likelihood_field”
- Description
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
Default
bool
False
- Description
Causes AMCL to set initial pose from the initial_pose* parameters instead of waiting for the initial_pose message.
- initial_pose:
Type
Default
Pose2D
{x: 0.0, y: 0.0, z: 0.0, yaw: 0.0}
- Description
X, Y, Z, and yaw coordinates of initial pose (meters and radians) of robot base frame in global frame.
- max_beams:
Type
Default
int
60
- Description
How many evenly-spaced beams in each scan to be used when updating the filter.
- max_particles:
Type
Default
int
2000
- Description
Maximum allowed number of particles.
- min_particles:
Type
Default
int
500
- Description
Minimum allowed number of particles.
- odom_frame_id:
Type
Default
string
“odom”
- Description
Which frame to use for odometry.
- pf_err:
Type
Default
double
0.05
- Description
Particle Filter population error.
- pf_z:
Type
Default
double
0.99
- Description
Particle filter population density. 2.33 is the 99% percentile.
- recovery_alpha_fast:
Type
Default
double
0.0
- Description
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
Default
double
0.0
- Description
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
Default
int
1
- Description
Number of filter updates required before resampling.
- robot_model_type:
Type
Default
string
“nav2_amcl::DifferentialMotionModel”
- Description
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.
- Note for users of galactic and earlier
The models are selectable by string key (valid options: “differential”, “omnidirectional”) rather than plugins.
- save_pose_rate:
Type
Default
double
0.5
- Description
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
Default
double
0.2
- Description
Standard deviation for Gaussian model used in z_hit part of the model.
- tf_broadcast:
Type
Default
bool
True
- Description
Set this to false to prevent amcl from publishing the transform between the global frame and the odometry frame.
- transform_tolerance:
Type
Default
double
1.0
- Description
Time with which to post-date the transform that is published, to indicate that this transform is valid into the future.
- update_min_a:
Type
Default
double
0.2
- Description
Rotational movement required before performing a filter update.
- update_min_d:
Type
Default
double
0.25
- Description
Translational movement required before performing a filter update.
- z_hit:
Type
Default
double
0.5
- Description
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
Default
double
0.05
- Description
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
Default
double
0.5
- Description
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
Default
double
0.005
- Description
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
Default
bool
False
- Description
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
Default
string
scan
- Description
Laser scan topic to subscribe to.
- map_topic:
Type
Default
string
map
- Description
Map topic to subscribe to.
- first_map_only:
Type
Default
bool
False
- Description
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. Prior to Humble, this is
first_map_only_.
- bond_heartbeat_period:
Type
Default
double
0.1
- Description
The lifecycle node bond mechanism publishing period (on the /bond topic). Disabled if inferior or equal to 0.0.
Example
amcl:
ros__parameters:
alpha1: 0.2
alpha2: 0.2
alpha3: 0.2
alpha4: 0.2
alpha5: 0.2
base_frame_id: "base_footprint"
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
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