Move Base 的配置文件分析

本文分析move base 的配置文件，从配置文件设置的角度，可以更清晰的把握move base对于costmap2D，global planner，local planner的调用关系。
这里采用turtlebot_navigation package 为例：

<launch>
  <include file="$(find turtlebot_navigation)/launch/includes/velocity_smoother.launch.xml"/>
  <include file="$(find turtlebot_navigation)/launch/includes/safety_controller.launch.xml"/>

  <arg name="odom_frame_id" default="odom"/>
  <arg name="base_frame_id" default="base_footprint"/>
  <arg name="global_frame_id" default="map"/>
  <arg name="odom_topic" default="odom" />
  <arg name="laser_topic" default="scan" />
  <arg name="custom_param_file" default="$(find turtlebot_navigation)/param/dummy.yaml"/>
  <!-- 以下部分是move base调用，需要配置的文件：包括全局地图，局部地图，全局planner，局部planner -->
  <node pkg="move_base" type="move_base" respawn="false" name="move_base" output="screen">
    <rosparam file="$(find turtlebot_navigation)/param/costmap_common_params.yaml" command="load" ns="global_costmap" />
    <rosparam file="$(find turtlebot_navigation)/param/costmap_common_params.yaml" command="load" ns="local_costmap" />   
    <rosparam file="$(find turtlebot_navigation)/param/local_costmap_params.yaml" command="load" />   
    <rosparam file="$(find turtlebot_navigation)/param/global_costmap_params.yaml" command="load" />
    <rosparam file="$(find turtlebot_navigation)/param/dwa_local_planner_params.yaml" command="load" />
    <rosparam file="$(find turtlebot_navigation)/param/move_base_params.yaml" command="load" />
    <rosparam file="$(find turtlebot_navigation)/param/global_planner_params.yaml" command="load" />
    <rosparam file="$(find turtlebot_navigation)/param/navfn_global_planner_params.yaml" command="load" />
    <!-- external params file that could be loaded into the move_base namespace -->
    <rosparam file="$(arg custom_param_file)" command="load" />

    <!-- reset frame_id parameters using user input data -->
    <param name="global_costmap/global_frame" value="$(arg global_frame_id)"/>
    <param name="global_costmap/robot_base_frame" value="$(arg base_frame_id)"/>
    <param name="local_costmap/global_frame" value="$(arg odom_frame_id)"/>
    <param name="local_costmap/robot_base_frame" value="$(arg base_frame_id)"/>
    <param name="DWAPlannerROS/global_frame_id" value="$(arg odom_frame_id)"/>

    <remap from="cmd_vel" to="navigation_velocity_smoother/raw_cmd_vel"/>
    <remap from="odom" to="$(arg odom_topic)"/>
    <remap from="scan" to="$(arg laser_topic)"/>
  </node>
</launch>

从上面的配置上来可以看到以下内容，这些都是关于地图的配置：

 /param/costmap_common_params.yaml" command="load" ns="global_costmap" 
 /param/costmap_common_params.yaml" command="load" ns="local_costmap" 
 /param/local_costmap_params.yaml" command="load" 
 /param/global_costmap_params.yaml" command="load" 

地图配置，首先是采用了一个costmap_common_params.yaml文件配置了一些公共的参数：

max_obstacle_height: 0.60 # assume something like an arm is mounted on top of the robot

# Obstacle Cost Shaping (http://wiki.ros.org/costmap_2d/hydro/inflation) robot_radius: 0.20 # distance a circular robot should be clear of the obstacle (kobuki: 0.18) # footprint: [[x0, y0], [x1, y1], ... [xn, yn]] # if the robot is not circular map_type: voxel obstacle_layer: enabled: true max_obstacle_height: 0.6 origin_z: 0.0 z_resolution: 0.2 z_voxels: 2 unknown_threshold: 15 mark_threshold: 0 combination_method: 1 track_unknown_space: true #true needed for disabling global path planning through unknown space obstacle_range: 2.5 raytrace_range: 3.0 origin_z: 0.0 z_resolution: 0.2 z_voxels: 2 publish_voxel_map: false observation_sources: scan bump scan: data_type: LaserScan topic: scan marking: true clearing: true min_obstacle_height: 0.25 max_obstacle_height: 0.35 bump: data_type: PointCloud2 topic: mobile_base/sensors/bumper_pointcloud marking: true clearing: false min_obstacle_height: 0.0 max_obstacle_height: 0.15 # for debugging only, let's you see the entire voxel grid #cost_scaling_factor and inflation_radius were now moved to the inflation_layer ns inflation_layer: enabled: true cost_scaling_factor: 5.0 # exponential rate at which the obstacle cost drops off (default: 10) inflation_radius: 0.5 # max. distance from an obstacle at which costs are incurred for planning paths. static_layer: enabled: true

然后分别设定global map 和local map：

global_costmap:
   global_frame: /map
   robot_base_frame: /base_footprint
   update_frequency: 1.0
   publish_frequency: 0.5
   static_map: true
   transform_tolerance: 0.5
   <!-- global map引入了以下三层，经融合构成了master map，用于global planner-->
   plugins:
     - {name: static_layer,            type: "costmap_2d::StaticLayer"}
     - {name: obstacle_layer,          type: "costmap_2d::VoxelLayer"}
     - {name: inflation_layer,         type: "costmap_2d::InflationLayer"}

local_costmap:
   global_frame: odom
   robot_base_frame: /base_footprint
   update_frequency: 5.0
   publish_frequency: 2.0
   static_map: false
   rolling_window: true
   width: 4.0
   height: 4.0
   resolution: 0.05
   transform_tolerance: 0.5
   <!-- local map引入了以下两层，经融合构成了master map，用于局部planner-->
   plugins:
    - {name: obstacle_layer,      type: "costmap_2d::VoxelLayer"}
    - {name: inflation_layer,     type: "costmap_2d::InflationLayer"}

然后是planner的配置：

 /param/move_base_params.yaml" command="load" 

 /param/global_planner_params.yaml" command="load" 
 /param/navfn_global_planner_params.yaml" command="load" 

 /param/dwa_local_planner_params.yaml" command="load" 

文件move_base_params.yaml 内容

shutdown_costmaps: false

controller_frequency: 5.0 controller_patience: 3.0  planner_frequency: 1.0 planner_patience: 5.0 oscillation_timeout: 10.0 oscillation_distance: 0.2 # local planner - default is trajectory rollout base_local_planner: "dwa_local_planner/DWAPlannerROS" <!--这里配置了local planner为dwa_local_planner --> <!--这里配置了global planner为navfn/NavfnROS --> base_global_planner: "navfn/NavfnROS" #alternatives: global_planner/GlobalPlanner, carrot_planner/CarrotPlanner

对于global planner，可以采用以下三种实现之一：

"navfn/NavfnROS","global_planner/GlobalPlanner","carrot_planner/CarrotPlanner"

然后来看global planner的配置：

GlobalPlanner:  # Also see: http://wiki.ros.org/global_planner
  old_navfn_behavior: false # Exactly mirror behavior of navfn, use defaults for other boolean parameters, default false
  use_quadratic: true # Use the quadratic approximation of the potential. Otherwise, use a simpler calculation, default true
  use_dijkstra: true # Use dijkstra's algorithm. Otherwise, A*, default true
  use_grid_path: false # Create a path that follows the grid boundaries. Otherwise, use a gradient descent method, default false

 allow_unknown: true # Allow planner to plan through unknown space, default true #Needs to have track_unknown_space: true in the obstacle / voxel layer (in costmap_commons_param) to work planner_window_x: 0.0 # default 0.0 planner_window_y: 0.0 # default 0.0 default_tolerance: 0.0 # If goal in obstacle, plan to the closest point in radius default_tolerance, default 0.0 publish_scale: 100 # Scale by which the published potential gets multiplied, default 100 planner_costmap_publish_frequency: 0.0 # default 0.0 lethal_cost: 253 # default 253 neutral_cost: 50 # default 50 cost_factor: 3.0 # Factor to multiply each cost from costmap by, default 3.0 publish_potential: true # Publish Potential Costmap (this is not like the navfn pointcloud2 potential), default true

对于local planner ，有以下两种选择：

"trajectory rollout","dwa_local_planner/DWAPlannerROS"

以下配置了DWAPlannerROS ：

DWAPlannerROS:

# Robot Configuration Parameters - Kobuki
  max_vel_x: 0.5  # 0.55
  min_vel_x: 0.0 

  max_vel_y: 0.0  # diff drive robot
  min_vel_y: 0.0  # diff drive robot

  max_trans_vel: 0.5 # choose slightly less than the base's capability
  min_trans_vel: 0.1  # this is the min trans velocity when there is negligible rotational velocity
  trans_stopped_vel: 0.1

  # Warning!
  # do not set min_trans_vel to 0.0 otherwise dwa will always think translational velocities
  # are non-negligible and small in place rotational velocities will be created.

  max_rot_vel: 5.0  # choose slightly less than the base's capability
  min_rot_vel: 0.4  # this is the min angular velocity when there is negligible translational velocity
  rot_stopped_vel: 0.4

  acc_lim_x: 1.0 # maximum is theoretically 2.0, but we 
  acc_lim_theta: 2.0
  acc_lim_y: 0.0      # diff drive robot

# Goal Tolerance Parameters
  yaw_goal_tolerance: 0.3  # 0.05
  xy_goal_tolerance: 0.15  # 0.10
  # latch_xy_goal_tolerance: false

# Forward Simulation Parameters
  sim_time: 1.0       # 1.7
  vx_samples: 6       # 3
  vy_samples: 1       # diff drive robot, there is only one sample
  vtheta_samples: 20  # 20

# Trajectory Scoring Parameters
  path_distance_bias: 64.0      # 32.0 - weighting for how much it should stick to the global path plan
  goal_distance_bias: 24.0      # 24.0 - wighting for how much it should attempt to reach its goal
  occdist_scale: 0.5            # 0.01 - weighting for how much the controller should avoid obstacles
  forward_point_distance: 0.325 # 0.325 - how far along to place an additional scoring point
  stop_time_buffer: 0.2         # 0.2 - amount of time a robot must stop in before colliding for a valid traj.
  scaling_speed: 0.25           # 0.25 - absolute velocity at which to start scaling the robot's footprint
  max_scaling_factor: 0.2       # 0.2 - how much to scale the robot's footprint when at speed.

# Oscillation Prevention Parameters
  oscillation_reset_dist: 0.05  # 0.05 - how far to travel before resetting oscillation flags

# Debugging
  publish_traj_pc : true
  publish_cost_grid_pc: true
  global_frame_id: odom


# Differential-drive robot configuration - necessary?
# holonomic_robot: false