Home Service Robot

Final project for Udacity's Robotics Software Engineer Nanodegree Program

Project Goals

The goal of this project was to design a robot's environment in gazebo and program the home-service robot that will map it's environment and autonomously navigate to pre-specified pickup and drop-off locations. For this one needed to:

• Design robot's environment with the Building Editor in Gazebo.
• Teleoperate the robot and manually test SLAM.
• Use the ROS navigation stack and manually command the robot using the 2D Nav Goal arrow in rviz to move to 2 different desired positions and orientations.
• Write a pick_objects node that commands the robot to move to the desired pickup and drop off zones.
• Write an add_markers node that subscribes to the robot odometry and publishes pick-up and drop-off markers to rviz.
• modify pick_objects node and add_markers node to establish communication between them, to complete desired home service robot implementation

Prerequisites

(since I have not tested on multiple platforms, and versions, I am listing only the configuration I used)

• Ubuntu 16.04 OS with default make (>=4.1) and g++/gcc (>=5.4) packages
• Gazebo >= 7.0
• ROS Kinetic
• following ROS packages were used and the process of obtaining them is detailed below:
  • gmapping
  • turtlebot_teleop
  • turtlebot_rviz_launchers
  • turtlebot_gazebo

Directory Tree and contents

.
├── README.md
├── images
│   ├── ... ...
├── CMakeLists.txt
├── add_markers
│   ├── launch
│   │   └── home_service_rviz_config.launch
│   └── src
│       ├── add_markers.cpp
│       └── add_markers_test.cpp
│   ├──  ... ...
├── config
│   └── marker_config.yaml
├── map
│   ├── building
│   │   ├── ... ...
│   ├── home_service.world
│   ├── home_service_map.pgm
│   ├── home_service_map.yaml
├── pick_objects
│   └── src
│       ├── pick_objects.cpp
│       └── pick_objects_test.cpp
│   ├──  ... ...
├── rvizConfig
│   └── home_service.rviz
├── scripts
│   ├── add_marker.sh
│   ├── home_service.sh
│   ├── pick_objects.sh
│   ├── test_navigation.sh
│   └── test_slam.sh
├── slam_gmapping
│   ├── gmapping
│   |── ... ...
├── turtlebot
│   |── turtlebot_teleop
│   |── ... ...
├── turtlebot_interactions
│   |── turtlebot_rviz_launchers
│   |── ... ...
|── turtlebot_simulator
│   ├── turtlebot_gazebo
│   |── ... ...

This directory represents the main project's src folder structure with following contents

• README.md: this file.
• images - folder with images and videos for this report
• add_markers - add marker C++ node
• config - folder with configuration file to specify pick-up and drop-off locations
• map - map and gazebo world files
• pick_objects - pick-objects C++ node
• rvizConfig - folder with rViz configurations used with some launch scripts
• scripts - shell scripts
  • add_marker.sh - script for testing add_marker concept with add_markers_test.cpp
  • home_service.sh - main script for the home-service-robot
  • pick_objects.sh - script for testing pick_objects concept with pick_objects_test
  • test_navigation.sh - script for testing navigation
  • test_slam.sh - script for performing SLAM and preparing map
• slam_gmapping - official ROS package with gmapping_demo.launch file
• turtlebot - official ROS package with keyboard_teleop.launch file
• turtlebot_interactions - official ROS package with view_navigation.launch file
• turtlebot_simulator - official ROS package with turtlebot_world.launch file

---

Clone and Build

Since the folder presented here comprises only of ROS package, one needs to first create a catkin workspace and initialize it. Also, note that the official ROS packaged are already included here, but their dependencies need to be installed; steps for this are given below.

Within your home directory, execute the following:

mkdir -p catkin_ws/src
cd catkin_ws/src
catkin_init_workspace

Within ~/catkin_ws/src/ download or clone folders of this repository:

cd ~/catkin_ws/src/
git clone https://github.com/viks8dm/home-service-robot.git

Install dependencies:

rosdep -i install gmapping -y
rosdep -i install turtlebot_teleop -y
rosdep -i install turtlebot_rviz_launchers -y
rosdep -i install turtlebot_gazebo -y

NOTE: If any of the official packages give error, I recommed you delete associated folder and clone with src folder using appropriate line from here:

git clone https://github.com/ros-perception/slam_gmapping.git  
git clone https://github.com/turtlebot/turtlebot.git  
git clone https://github.com/turtlebot/turtlebot_interactions.git  
git clone https://github.com/turtlebot/turtlebot_simulator.git

Go back to catkin workspace and build it

cd ~/catkin_ws/
catkin_make

Launch specific application and visualize

Specific applications can be launched using scripts provided. In this section I will go over how I have used these scripts.

Gazebo-world, SLAM test & map-creation

For my world file I started with the gazebo-world I have used in past (like the one in https://github.com/viks8dm/mapping_ROS). However, during SLAM and map preparation I realized that this world had following flaws:

• it has very few features and a lot of open space. This leads to gmapping error with following messages:
  • Scan Matching Failed, using odometry. Likelihood=0
• There were two carts in the model which were not fixed. So while the robot completed a loop and came back to a spot near one of the carts, the mapping algorithm was getting confused and resulting in image rotation in rviz, similar to that shown below.

Fig.1: gmapping-error sample

Hence I added features to the world and updated it to that shown here:

Fig.2: home-service-world

For SLAM-test go to src/scripts folder and run test_slam.sh script:

cd ~/catkin_ws/src/scripts
./test_slam.sh

This will launch:

• turtlebot_world.launch to deploy turtlebot in my world with specific pose
• gmapping_demo.launch to perform SLAM
• view_navigation.launch to observe map in rviz
• keyboard_teleop.launch to manually control robot

After navigating the robot around multiple times, once I was satisfied with the map appearance in comparison to the world-file, I saved it using:

rosrun map_server map_saver -f <map-location-and-name>

The corresponding map looks as follows:

Fig.3: saved-map

Localization and navigation test

For localization testing, I used test_localization.sh as follows:

cd ~/catkin_ws/src/scripts
./test_localization.sh

This will launch:

• turtlebot_world.launch to deploy turtlebot in my world with specific pose
• amcl_demo.launch to localize turtlebot
• view_navigation.launch to observe map in rviz

I used 2D Nav tab in rviz to manually point out to two different goals, one at a time, and direct the robot to reach them and orient itself with respect to them. A sample image is shown below and the sample video can be found here

Fig.4: navigation-test sample

Navigation Goal Node (pick-objects)

To test robot's capability to reach multiple goals, as specified by the program (and not manually), I created pick_objects package and specifically pick_objects_test.cpp function. This can be tested following script which launches turtlebot, AMCL, rviz and pick_objects node:

cd ~/catkin_ws/src/scripts
./pick_objects.sh

Virtual Objects Node (add-markers)

To model a virtual object with markers in rviz, I created add_markers package and specifically add_markers_test.cpp function. This can be tested following script which launches turtlebot, AMCL, rviz and add_markers node:

cd ~/catkin_ws/src/scripts
./add_markers.sh

A sampe output is shown here:

Fig.5: virtual object addition test

Home-Service-Robot package

To simulate a full home service robot capable of navigating to pick up and deliver virtual objects, communication was established between the add_markers and pick_objects nodes via a "/goal_reached" topic. For this purpose modified versions of previous test codes were created respectively pick_objects.cpp and add_markers.cpp. The entire package can be launched using:

cd ~/catkin_ws/src/scripts
./home_service.sh

The result can be seen in the gif display above or at one of these video links:

• home-service-robot's rviz window: https://youtu.be/iy3RJXRyFkw
• home-service-robot's rviz with messages: https://youtu.be/mAXX1b7Ap_k