Frontier Description

This package contains the URDF description file of the Frontier, a compact handheld device designed to perform visual-inertial and LIDAR navigation algorithms. It was previously known as Rooster (Realsense + Ouster) until 2022.

Dependencies:

• realsense2_description available from the Intel's repo or APT (ros-noetic-realsense2-description)
• ddynamic_reconfigure this is a dependency of the realsense2_camera that should be available through APT (ros-noetic-ddynamic-reconfigure).
• ouster_description available at the DRS fork of the ouster_example repository
• alphasense_description is the unofficial URDF for the alphasense

Files

• frontier.urdf.xacro: macro definition of the Frontier device, which you can instantiate on any robot
• frontier_standalone.urdf.xacro: Frontier as a standalone robot. The root link is called base and its origin is coincident with the camera_link frame (see below)
• microstrain.urdf.xacro: macro definition of the Microstrain 3DM-GX4-45 and 3DM-GX4-25 inertial measurement units

Frontier Macro Parameters

• simulation: if true, it generates all the links for optical frames that are normally advertized by the sensor drivers
• parent: name of the root link of the device (default is: base)
• origin: xacro block that connects parent to frontier_mount
• use_ouster: load the ouster OS lidar instead of the Hesai Pandar
• rotate_ouster: rotate the ouster lidar by 45 degrees (ignored if use_ouster is false)
• raise_lidar: raises the ouster lidar by 4 mm (some models have standoff, soon to be deprecated)
• use_realsense: load the RealSense D435i instead of the Alphasense Dev Kit

Standalone Frontier Xacro Arguments:

The following arguments are ported from the macro to the standalone macro:

• simulation
• use_ouster
• rotate_ouster
• use_realsense
• raise_lidar

Standalone Frontier URDF Frames:

• base : coincident with the left camera optical frame with x-forward, y-left, z-up convention. The ground truth is expressed in this frame.
• frontier_mount: located at the bottom of the Frontier, with z-axis coincident with the ouster sensor frame.
• realsense_parent : the frame located at the bottom screw hole plate of the RealSense D435i is located here
• os_sensor : conventional base link for the Ouster. It is at the bottom of the sensor and the top of the Frontier, 0 deg (or 45 deg clockwise rotated on z-axis if rotate_ouster = true).
• os_lidar : is looking backward and is in the middle of the sensor. Not used anymore, pointcluds from the ouster are expressed in os_sensor since firmeware 2.0
• os_imu : has fixed offset from os_sensor retrived from documentation or via interactive probing to the device.
• bottom_screws_center: Convenience frame used for mounting on other robots only. It is at the intersection between the lines connecting the bottom screw holes (not visible on URDF).
• alphasense_mount: frame at the bottom of the alphasense, in the middle of the mounting screws
• alphasense_imu: IMU located inside the Alphasense Dev Core Kit
• hesai_base: located at the bottom of the hesai, concentric with the axis of rotation and with x-axis pointing forward
• pandar: sensor origin, with x-axis pointing left
• cam_front_left,cam_front_right,cam_side_left,cam_side_right: optical centers of the Alphasense's cameras

Example

This launches RViz and shows the various frames of the standalone robot:

roslaunch frontier_description view_urdf.launch

URDF Generation and Inspection

You can generate the URDF with all the simulated frames by launchng the xacro command.
The resulting URDF can be then inspected with the urdf_to_graphiz utility:

xacro frontier_standalone.urdf.xacro simulation:=true > frontier.urdf
urdf_to_graphiz frontier.urdf
evince frontier.pdf