Speed Filter Parameters

Speed Filter - is a Costmap Filter that restricting maximum velocity of robot. The areas where robot should slow down and values of maximum allowed velocities are encoded at filter mask. Filter mask published by Map Server, goes in a pair with filter info topic published by Costmap Filter Info Server. Speed Filter itself publishes a speed restricting messages which are targeted for a Controller in order to make the robot to not exceed the required velocity.

<filter name>: is the corresponding plugin name selected for this type.

<filter name>.enabled:
 
Type Default
bool True
Description

Whether it is enabled.

<filter name>.filter_info_topic:
 
Type Default
string N/A
Description

Name of the incoming CostmapFilterInfo topic having filter-related information. Published by Costmap Filter Info Server along with filter mask topic. For more details about Map and Costmap Filter Info servers configuration please refer to the Map Server / Saver configuration page.

<filter name>.speed_limit_topic:
 
Type Default
string “speed_limit”
Description

Topic to publish speed limit to. The messages have the following fields’ meaning:

  • percentage: speed limit is expressed in percentage if true or in absolute values in false case. This parameter is set depending on type field of CostmapFilterInfo message.

  • speed_limit: non-zero values show maximum allowed speed expressed in a percent of maximum robot speed or in absolute value depending on percentage value. Zero value means no speed restriction (independently on percentage). speed_limit is being linearly converted from OccupancyGrid filter mask value as: speed_limit = base + multiplier * mask_value, where base and multiplier coefficients are taken from CostmapFilterInfo message.

    Note

    speed_limit expressed in a percent should belong to (0.0 .. 100.0] range.

This topic will be used by a Controller Server. Please refer to Controller Server configuration page to set it appropriately.

<filter name>.transform_tolerance:
 
Type Default
double 0.1
Description

Time with which to post-date the transform that is published, to indicate that this transform is valid into the future. Used when filter mask and current costmap layer are in different frames.

Example

global_costmap:
  global_costmap:
    ros__parameters:
    ...
    plugins: ["static_layer", "obstacle_layer", "inflation_layer"]
    filters: ["speed_filter"]
    ...
    speed_filter:
      plugin: "nav2_costmap_2d::SpeedFilter"
      enabled: True
      filter_info_topic: "/costmap_filter_info"
      speed_limit_topic: "/speed_limit"
      transform_tolerance: 0.1