@849282206 在 ros2 实现 AMCL定位 中说：
你好，小鱼。我目前跟随你的ros2教程学习到Nav2导航篇，按照教程的例子，实现了小车的单点导航和多点导航。但是有个问题，启动后，我需要手动大概指定机器人的位姿，而且指定完之后，初始状态的粒子波只有很小一圈。我的理解是，机器人在初始状态下，粒子波应该是均匀分布在整个地图的，当机器人运动起来后，会慢慢确定自己的位置。请问，这个应该如何实现？
initial_pose_x: 0.0 initial_pose_y: 0.0 initial_pose_a: 0.0 initial_cov_xx: 32 initial_cov_yy: 32 initial_cov_zz: 32
我在fishbot_nav2.yaml文件中，加入了如下代码段，编译成功后，运行失败。希望得到你的指导。
fishbot_nav2.yaml完整的代码文件如下：
amcl: ros__parameters: use_sim_time: True alpha1: 0.2 alpha2: 0.2 alpha3: 0.2 alpha4: 0.2 alpha5: 0.2 base_frame_id: "base_link" 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: 5000 min_particles: 500 initial_pose_x: 0.0 initial_pose_y: 0.0 initial_pose_a: 0.0 initial_cov_xx: 32 initial_cov_yy: 32 initial_cov_zz: 32 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: 10.0 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 amcl_map_client: ros__parameters: use_sim_time: True amcl_rclcpp_node: ros__parameters: use_sim_time: True bt_navigator: ros__parameters: use_sim_time: True global_frame: map robot_base_frame: base_link odom_topic: /odom bt_loop_duration: 10 default_server_timeout: 20 # 'default_nav_through_poses_bt_xml' and 'default_nav_to_pose_bt_xml' are use defaults: # nav2_bt_navigator/navigate_to_pose_w_replanning_and_recovery.xml # nav2_bt_navigator/navigate_through_poses_w_replanning_and_recovery.xml # They can be set here or via a RewrittenYaml remap from a parent launch file to Nav2. plugin_lib_names: - nav2_compute_path_to_pose_action_bt_node - nav2_compute_path_through_poses_action_bt_node - nav2_smooth_path_action_bt_node - nav2_follow_path_action_bt_node - nav2_spin_action_bt_node - nav2_wait_action_bt_node - nav2_back_up_action_bt_node - nav2_drive_on_heading_bt_node - nav2_clear_costmap_service_bt_node - nav2_is_stuck_condition_bt_node - nav2_goal_reached_condition_bt_node - nav2_goal_updated_condition_bt_node - nav2_globally_updated_goal_condition_bt_node - nav2_is_path_valid_condition_bt_node - nav2_initial_pose_received_condition_bt_node - nav2_reinitialize_global_localization_service_bt_node - nav2_rate_controller_bt_node - nav2_distance_controller_bt_node - nav2_speed_controller_bt_node - nav2_truncate_path_action_bt_node - nav2_truncate_path_local_action_bt_node - nav2_goal_updater_node_bt_node - nav2_recovery_node_bt_node - nav2_pipeline_sequence_bt_node - nav2_round_robin_node_bt_node - nav2_transform_available_condition_bt_node - nav2_time_expired_condition_bt_node - nav2_path_expiring_timer_condition - nav2_distance_traveled_condition_bt_node - nav2_single_trigger_bt_node - nav2_is_battery_low_condition_bt_node - nav2_navigate_through_poses_action_bt_node - nav2_navigate_to_pose_action_bt_node - nav2_remove_passed_goals_action_bt_node - nav2_planner_selector_bt_node - nav2_controller_selector_bt_node - nav2_goal_checker_selector_bt_node - nav2_controller_cancel_bt_node - nav2_path_longer_on_approach_bt_node - nav2_wait_cancel_bt_node - nav2_spin_cancel_bt_node - nav2_back_up_cancel_bt_node - nav2_drive_on_heading_cancel_bt_node bt_navigator_rclcpp_node: ros__parameters: use_sim_time: True controller_server: ros__parameters: use_sim_time: True controller_frequency: 20.0 min_x_velocity_threshold: 0.001 min_y_velocity_threshold: 0.5 min_theta_velocity_threshold: 0.001 failure_tolerance: 0.3 progress_checker_plugin: "progress_checker" goal_checker_plugins: ["general_goal_checker"] # "precise_goal_checker" controller_plugins: ["FollowPath"] # Progress checker parameters progress_checker: plugin: "nav2_controller::SimpleProgressChecker" required_movement_radius: 0.5 movement_time_allowance: 10.0 # Goal checker parameters #precise_goal_checker: # plugin: "nav2_controller::SimpleGoalChecker" # xy_goal_tolerance: 0.25 # yaw_goal_tolerance: 0.25 # stateful: True general_goal_checker: stateful: True plugin: "nav2_controller::SimpleGoalChecker" xy_goal_tolerance: 0.25 yaw_goal_tolerance: 0.25 # DWB parameters FollowPath: plugin: "dwb_core::DWBLocalPlanner" debug_trajectory_details: True min_vel_x: 0.0 min_vel_y: 0.0 max_vel_x: 0.26 max_vel_y: 0.0 max_vel_theta: 1.0 min_speed_xy: 0.0 max_speed_xy: 0.26 min_speed_theta: 0.0 # Add high threshold velocity for turtlebot 3 issue. # https://github.com/ROBOTIS-GIT/turtlebot3_simulations/issues/75 acc_lim_x: 2.5 acc_lim_y: 0.0 acc_lim_theta: 3.2 decel_lim_x: -2.5 decel_lim_y: 0.0 decel_lim_theta: -3.2 vx_samples: 20 vy_samples: 5 vtheta_samples: 20 sim_time: 1.7 linear_granularity: 0.05 angular_granularity: 0.025 transform_tolerance: 0.2 xy_goal_tolerance: 0.25 trans_stopped_velocity: 0.25 short_circuit_trajectory_evaluation: True stateful: True critics: ["RotateToGoal", "Oscillation", "BaseObstacle", "GoalAlign", "PathAlign", "PathDist", "GoalDist"] BaseObstacle.scale: 0.02 PathAlign.scale: 32.0 PathAlign.forward_point_distance: 0.1 GoalAlign.scale: 24.0 GoalAlign.forward_point_distance: 0.1 PathDist.scale: 32.0 GoalDist.scale: 24.0 RotateToGoal.scale: 32.0 RotateToGoal.slowing_factor: 5.0 RotateToGoal.lookahead_time: -1.0 controller_server_rclcpp_node: ros__parameters: use_sim_time: True local_costmap: local_costmap: ros__parameters: update_frequency: 5.0 publish_frequency: 2.0 global_frame: odom robot_base_frame: base_link use_sim_time: True rolling_window: true width: 3 height: 3 resolution: 0.05 robot_radius: 0.12 plugins: ["voxel_layer", "inflation_layer"] inflation_layer: plugin: "nav2_costmap_2d::InflationLayer" cost_scaling_factor: 3.0 inflation_radius: 0.35 voxel_layer: plugin: "nav2_costmap_2d::VoxelLayer" enabled: True publish_voxel_map: True origin_z: 0.0 z_resolution: 0.05 z_voxels: 16 max_obstacle_height: 2.0 mark_threshold: 0 observation_sources: scan scan: topic: /scan max_obstacle_height: 2.0 clearing: True marking: True data_type: "LaserScan" raytrace_max_range: 3.0 raytrace_min_range: 0.0 obstacle_max_range: 2.5 obstacle_min_range: 0.0 static_layer: map_subscribe_transient_local: True always_send_full_costmap: True local_costmap_client: ros__parameters: use_sim_time: True local_costmap_rclcpp_node: ros__parameters: use_sim_time: True global_costmap: global_costmap: ros__parameters: update_frequency: 1.0 publish_frequency: 1.0 global_frame: map robot_base_frame: base_link use_sim_time: True robot_radius: 0.12 resolution: 0.05 track_unknown_space: true plugins: ["static_layer", "obstacle_layer", "inflation_layer"] obstacle_layer: plugin: "nav2_costmap_2d::ObstacleLayer" enabled: True observation_sources: scan scan: topic: /scan max_obstacle_height: 2.0 clearing: True marking: True data_type: "LaserScan" raytrace_max_range: 3.0 raytrace_min_range: 0.0 obstacle_max_range: 2.5 obstacle_min_range: 0.0 static_layer: plugin: "nav2_costmap_2d::StaticLayer" map_subscribe_transient_local: True inflation_layer: plugin: "nav2_costmap_2d::InflationLayer" cost_scaling_factor: 3.0 inflation_radius: 0.35 always_send_full_costmap: True global_costmap_client: ros__parameters: use_sim_time: True global_costmap_rclcpp_node: ros__parameters: use_sim_time: True map_server: ros__parameters: use_sim_time: True yaml_filename: "turtlebot3_world.yaml" map_saver: ros__parameters: use_sim_time: True save_map_timeout: 5.0 free_thresh_default: 0.25 occupied_thresh_default: 0.65 map_subscribe_transient_local: True planner_server: ros__parameters: expected_planner_frequency: 20.0 use_sim_time: True planner_plugins: ["GridBased"] GridBased: plugin: "nav2_navfn_planner/NavfnPlanner" tolerance: 0.5 use_astar: false allow_unknown: true planner_server_rclcpp_node: ros__parameters: use_sim_time: True smoother_server: ros__parameters: use_sim_time: True smoother_plugins: ["simple_smoother"] simple_smoother: plugin: "nav2_smoother::SimpleSmoother" tolerance: 1.0e-10 max_its: 1000 do_refinement: True behavior_server: ros__parameters: costmap_topic: local_costmap/costmap_raw footprint_topic: local_costmap/published_footprint cycle_frequency: 10.0 behavior_plugins: ["spin", "backup", "drive_on_heading", "wait"] spin: plugin: "nav2_behaviors/Spin" backup: plugin: "nav2_behaviors/BackUp" drive_on_heading: plugin: "nav2_behaviors/DriveOnHeading" wait: plugin: "nav2_behaviors/Wait" global_frame: odom robot_base_frame: base_link transform_tolerance: 0.1 use_sim_time: true simulate_ahead_time: 2.0 max_rotational_vel: 1.0 min_rotational_vel: 0.4 rotational_acc_lim: 3.2 robot_state_publisher: ros__parameters: use_sim_time: True waypoint_follower: ros__parameters: loop_rate: 20 stop_on_failure: false waypoint_task_executor_plugin: "wait_at_waypoint" wait_at_waypoint: plugin: "nav2_waypoint_follower::WaitAtWaypoint" enabled: True waypoint_pause_duration: 200