Before installing the simulation environment, make sure your desktop is setup with a standard installation of ROS Indigo on Ubuntu 14.04. Once your APT repositories are configured, you can install the simulator:
>$ sudo apt-get update >$ sudo apt-get install ros-indigo-fetch-gazebo-demo
Warning
Never run the simulator on the robot. Simulation requires that the ROS parameter use_sim_time be set to true, which will cause the robot drivers to stop working correctly. In addition, be sure to never start the simulator in a terminal that has the ROS_MASTER_URI set to your robot for the same reasons.
The fetch_gazebo and fetch_gazebo_demo packages provide the Gazebo environment for Fetch. fetch_gazebo includes several launch files:
- simulation.launch spawns a robot in an empty world.
- playground.launch spawns a robot inside a lab-like test environment. This environment has some tables with items that may be picked up and manipulated. It also has a pre-made map which can be used to test out robot navigation and some simple demonstrations of object grasping.
To start the simplest environment with Freight
>$ roslaunch fetch_gazebo simulation.launch robot:=freight
Puzzle: While I am using the default argument, I see the Fetch robot but without the lidar scan which I don‘t know why.
Adding a Brick wall to see how lidar scan works:
Even though Gazebo has a graphical visualization, RVIZ is still the preferred tool for interacting with your robot.
>$ rosrun rviz rviz
Simulating a Freight in Gazebo
原文：http://www.cnblogs.com/casperwin/p/6049508.html