FAQ

FAQ

Why can't the arm controller find the move_arm server even though it's running?

The move_arm server won't reconnect to a new arm once it loses its connection. Try restarting roscore (or not launching it in the first place; ROS automatically starts roscore when a node is started from a launch file.) If that doesn't work, restart the arm navigation server.

Why is everything upside-down in rviz?

The rviz coordinate system assumes that the positive z-axis points upwards (and the camera rotation controls follow this convention). USARSim coordinates treat positive z as downwards, so anything from USARSim will be displayed upside-down in rviz.

The usarsim_tools package contains a small node (base_transform) that will continually publish an additional transformation frame (called /rviz_base) as the parent of the conventional USARSim world frame (/odom). The two frames are separated by a rotation of 180 degrees about the y axis, so if /rviz_base is used as the rviz Fixed Frame, the robot should appear right side up. To run the node, run $rosrun usarsim_tools base_transform , and make sure /rviz_base is set in rviz as the Fixed Frame. This node will need to be restarted whenever the current robot is.

What name should I give the GroundTruth sensor?

Specify the name of the GroundTruth sensor by setting the usarsim/odomSensor parameter in the launch file. Set the name to match the name of a GroundTruth sensor on the robot in the world.

What should I do with the autogenerated URDF file?

The planning configuration wizard, the tf state publisher, rviz, and the arm navigation server all need URDF information to run correctly. These nodes check the robot_description parameter, which holds the contents (not the path) of an URDF file. Move the URDF file to usarsim_inf/urdf, and add the following line to any launch file that starts a node that might need the URDF (replacing urdf_file_name appropriately):

<param name = "robot_description" command = "cat $(find usarsim_inf)/urdf/<urdf_file_name>" />

Why can't I see ROS_INFO, ROS_WARN, or ROS_DEBUG messages?

By default, only ROS_ERROR logs will display in the console when a node is started from a launch file. To set all nodes to log their output to the screen, set the --screen parameter when starting a launch file.

Even with the screen parameter set, by default, ROS_DEBUG messages won't display in the console. See here for instructions on changing this behavior for specific nodes.