## For instruction on writing tutorials
## http://www.ros.org/wiki/WritingTutorials
####################################
##FILL ME IN
####################################
## for a custom note with links:
## note =
## for the canned note of "This tutorial assumes that you have completed the previous tutorials:" just add the links
## note.0=
## descriptive title for the tutorial
## title = How to set up hector_slam for your robot
## multi-line description to be displayed in search
## description =  This tutorial shows you how to set frame names and options for using hector_slam with different robot systems.
## the next tutorial description (optional)
## next =
## links to next tutorial (optional)
## next.0.link=
## next.1.link=
## what level user is this tutorial for
## level= BeginnerCategory
## keywords =
####################################
<<IncludeCSTemplate(TutorialCSHeaderTemplate)>>

<<TableOfContents(4)>>

= Overview =
[[hector_slam]] uses the [[hector_mapping]] node for learning a map of the environment and simultaneously estimating the platform's 2D pose at laser scanner frame rate. The frame names and options for [[hector_mapping]] have to be set correctly. This tutorial explains the different options. The image below shows all potential frames of interest in a simplified 2D view of a robot travelling through rough terrain, leading to roll and pitch motion of the platform:

[[attachment:coordsystems_img.png|{{attachment:coordsystems_img.png|attachment:coordsystems_img.png}}]]

The general relationship between the map, odom and base_link frames is already described in [[http://www.ros.org/reps/rep-0105.html|Coordinate Frames for Mobile Platforms]]. We use two frames in between odom and base_link: The base_footprint frame provides no height information and represents the 2D pose of the robot (position and orientation). The base_stabilized frame adds information about the robot height relative to the map/odom layer. The base_link frame is rigidly attached to the robot and adds the roll and pitch angles compared to the base_stabilized frame. For this transformation, a system for estimation of the vehicle attitude like a AHRS or INS can be used (can be realized using the [[hector_imu_attitude_to_tf|hector_imu_attitude_to_tf]] node for example). For a platform not exhibiting roll/pitch motion, the base_stabilized and base_link frames are equal. The transformation from base_link to laser_link is typically provided by a [[tf#static_transform_publisher|static transform publisher]] or the [[robot_state_publisher|robot state publisher]].

= Setup =
We assume that the reader has a basic understanding of ROS parameters and launch files for the following section. The [[hector_slam_launch]] package contains some launch files that might serve as examples. 
== Use in place of gmapping ==
[[gmapping]] publishes the map->odom transform. You have to set the following parameters of [[hector_mapping]] to reflect the setup on your platform:
{{{
    <param name="pub_map_odom_transform" value="true"/>
    <param name="map_frame" value="map" />
    <param name="base_frame" value="base_frame" />
    <param name="odom_frame" value="odom" />
}}}
If your platform exhibits roll/pitch motion you have to set the base_frame so it has the properties of the base_stabilized frame described in the Overview section above.

== Use without odom frame ==
If you do not require the use of a odom frame (for example because your platform does not provide any usable odometry) you can directly publish a transformation from map to base_link:
{{{
    <param name="pub_map_odom_transform" value="true"/>
    <param name="map_frame" value="map" />
    <param name="base_frame" value="base_frame" />
    <param name="odom_frame" value="base_frame" />
}}}

== Use without Broadcasting of transformations ==
The system can also be used without broadcasting any tf transformation. This can be useful if another node is responsible for publishing the map->odom or map->base_frame transform. This can be done by setting:
{{{
    <param name="pub_map_odom_transform" value="false"/>
}}}
In this case, the estimated pose published on the poseupdate topic of [[hector_mapping]] might be used for example by a INS system which then publishes a map->base_frame transform.


## AUTOGENERATED DO NOT DELETE
## TutorialCategory
## FILL IN THE STACK TUTORIAL CATEGORY HERE