ROS udacity_bot robot model package

Author: Roberto Zegers R.

Abstract

This package contains a URDF model of a differential drive robot equipped with a camera and laser sensor.

Fig.1 Image of the robot model in Gazebo (coke_can model shown for size comparison).

Default topics

Image Topic: /udacity_bot/camera1/image_raw
Image Info Topic:/udacity_bot/camera1/camera_info
Laser Scan Topic: /udacity_bot/laser/scan
Odometry Topic: /odom
Movement Commands: /cmd_vel

To spaw the robot into a running Gazebo simulation with a custom Odometry Topic append an argument like this:
$ roslaunch udacity_bot spawn_udacity_bot.launch odometryTopic:=odom_perfect

Repository architecture

Directories

urdf/ : (required) contains the files that generate the robot model and provide simulated actuators and sensors
meshes/ : (required) contains the mesh files of the laser sensor
config/ : (optional) contains YAML files that store the Navigation Stack configuration files for the robot
rviz/ : (optional) contains Rviz configuration settings for displaying the robot model
launch/ : (optional) contains launch files for starting the simulation / running nodes
worlds/ : (optional) contains scene/environment files for Gazebo
maps/ : (optional) contains the occupancy grid based maps required for navigation

Robot model files

udacity_bot.xacro : the xacro file that generates the urdf description file of the robot
udacity_bot.gazebo : contains the Gazebo plugins that provide an interface to control the robot wheels and simulate the laser sensor

Direct usage

Clone this repository into a ROS catkin workspace
Build and source the workspace
To view this robot model on an empty Gazebo world: $ roslaunch udacity_bot empty_world.launch
To launch this package including the Jackal Race Gazebo world and Rviz: $ roslaunch udacity_bot udacity_world.launch use_rviz:=true
or:
To spawn the robot into another already opened Gazebo world:
$ roslaunch udacity_bot spawn_udacity_bot.launch

If you want to move the robot using a keyboard you will also need to start a teleop node.
To run the AMCL localization node and use the robot with the Navigation Stack type in a new window: roslaunch udacity_bot amcl.launch

To view raw images on the topic /camera/rgb/image_raw, use:
$ rosrun image_view image_view image:=/udacity_bot/camera1/image_raw

Mapping

First check that you satisfy all dependencies by running: $ rospack find gmapping
You can use this robot to build a map since it includes the required odometry and laser sensor. The inluded launch file mapping.launch will start Gazebo, load a predetermined world, and start the package gmapping properly configured, along with all other nodes required, including Rviz.
To move the robot around a telop node is also required, for instance you can use:
$ rosrun rqt_robot_steering rqt_robot_steering
At the beginning there could be no map in Rviz, you may need to wait few second until it is generated.

Known Issues

Gazebo is crashing as it is starting up: Usually, it is enough to run it again (probably several times).
Most of the visual robot model shapes are not shown or are displayed collapsed on Rviz: make sure to run robot_state_publisher to publish transforms for all joints.
Do it by running roslaunch udacity_bot robot_description.launch

This package has only been tested on Ubuntu 16.04 LTS with ROS Kinetic and Gazebo 7.0 and 7.15.

rfzeg/udacity_bot