[ROS Q&A] 078 – ROS Remap

Q: Remapping between nodes
How to remap between nodes in launch file. Plz guide.im using Ros indigo version

A: Basically, remap is a feature to rename topics, node names and some special keys of ROS env. You can see in this page what you can remap, like a node name (__node), namespace (__ns), log file (__log), etc.

Example: I’ve a node that publishes Twist messages in a topic called turtlebot_vel, but my robot listens to cmd_vel

You can remap using rosrun command, like this:

[ROS Q&A] 077 – How to solve the SetMaxForce error in Gazebo

In this video I’m going to show how to easily solve the following error:
error: ‘class gazebo::physics::Joint’ has no member named ‘SetParam’

[ROS Q&A] 076 – How to get the closest obstacle with rotating laser

Q: How to get the distance to obstacles given that the laser is rotating?
Original question: https://answers.ros.org/question/229865/how-to-incorporate-moveable-sensor-lidar-into-navigation-stack

A: By using TF to transform the obstacle detected to the base_link of the robot.

[ROS Q&A] 075 – 3rd time getting stuck at “Building a ROS Package”

In this question we see how to solve the problem when running catkin_make on a Catkin Workspace: The specified base path /home/user/catkin_ws contains a CMakeLists.txt but catkin_make must be invoked in the root of workspace

Q: https://answers.ros.org/question/277210/3rd-time-getting-stuck-at-building-a-ros-package/

A: The problem is because the user had a CMakeLists.txt on the root folder of the Workspace (~/catkin_ws/CMakeLists.txt). The file must be on the src folder: ~/catkin_ws/src/CMakeLists.txt

[ROS Q&A] 074 – Aerodynamic parameters of lift-drag plugin part2

In this video we complete the answer given previously ( https://www.youtube.com/watch?v=I-dhwqxV7QM ) with a more complex shape. Here is the question: http://answers.gazebosim.org/question/15331/need-information-on-aerodynamic-parameters-of-lift-drag-plugin/#17793

Q: Need information on aerodynamic parameters of lift-drag plugin
A: You have to calculate the area for the new shapes and also decide the axis for the front and upwards forces.

[ROS Q&A] 073 – How to add a simple wall to a Gazebo world

Q: I created a custom gazebo world for my turtleBot containing several walls and saved it as a .world file. However when I run the world file the walls that i created do not load.

A: Here you can see a simple example of how to launch a simple Gazebo world with a wall in it.

Related ROS Answers Question: https://answers.ros.org/question/277170/custom-gazebo-world-doesnt-load/