Skip to content
Joe Norby edited this page Feb 17, 2022 · 24 revisions

Frequently Asked Questions

What is the convention for joint and leg numbering in the RobotState message?

The joint arrays in spirit_msgs::RobotState are defined such that indices 0 = abad0, 1 = hip0, 2 = knee1, 3 = abad1, 4 = hip1, 5 = knee12, 6 = abad2, 7 = hip2, 8 = knee2, 9 = abad3, 10 = hip3, 11 = knee3. Legs are numbered such that 0 = front left, 1 = back left, 2 = front right, and 3 = back right. So calling state_msg.joints.positions[4] would give you the joint position of the back left hip motor.

Confusingly, Ghost Robotics does NOT use this definition, and instead has their urdf and /mcu/state/jointURDF use the following ordering: 0 = hip0, 1 = knee0, 2 = hip1, 3 = knee1, 4 = hip2, 5 = knee2, 6 = hip3, 7 = knee3, 8 = abd0, 9 = abd1, 10 = abd2, 11 = abd3. To correct this, our ground_truth_publisher.cpp reads their message and maps from their ordering to ours, see the joints_order_ vector in the source code . Likewise our estimator_plugin.cpp maps from the alphabetical order in Gazebo to our order.

Common errors

Unable to communicate with master

ERROR: Unable to communicate with master!

No ROS master detected - if on the remote computer make sure to source launch_robot_env.sh (which sources the appropriate setup.bash). Otherwise you probably haven't issues and roslaunch commands yet.

Can't SSH into Jetson TX2

Power cycle the USB ethernet adapter by turn on&off the USB hub port.

Internal compiler error (during catkin build)

This typically happens when your system runs out of RAM while compiling. Try catkin build -j4 -l4, go even lower than 4 (this represents the number of parallel threads used while compiling), or try catkin build --this in the package you want to build to avoid compiling the whole workspace. Alternatively if you were running catkin test, try compiling just the source code first, then the tests after completion.

This could also be caused by other processes running in the background which may or not be ROS related. Sometimes nodes or tests that do not get terminated properly can consume significant resources in the background. Check to make sure you don't have something eating up your CPU overhead.

RViz crashes when using Clicked Point

This appears to be a known issue when using interactive markers with NVidia drivers. It can be fixed by rebuilding OGRE with an updated version (and then also RViz) or reverting to Nouveau drivers, but most likely we will eliminate the use of interactive markers for this reason.

Catkin: command not found (or any other packages)

The setup.sh script should install all the required dependencies, if not then likely sudo apt update failed. Check your packages.