Assignment 4: Mobile Manipulator Extra Credit Guide

CS498GC Mobile Robotics - Fall 2025

📅 Important Deadlines & Extra Credit Opportunities

Early Submission Bonus Points 🌟

  • Submit before November 9, 2025: +20 Bonus Points
  • Submit before November 14, 2025: +10 Bonus Points
  • Applies to: Assignment 4 Part 1

Regular Deadlines

  • Part 1: November 21, 2025 @ 11:00 PM (25 points)
  • Part 2: December 9, 2025 @ 11:00 PM (75 points)
  • Total Possible: 100 points + up to 20 bonus = 120 points

Gradescope Information

  • Course Code: KDP5G8
  • Submission Format: PDF report + rosbag file + screen recording

🎥 Demo Resources

Main Demo Recording

  • Link: Demo Recording
  • URL: https://drive.google.com/file/d/1TVCehZ8cksYwapauqrUs_4s2lsiecR_E/view?usp=share_link
  • Note: Only the first video’s window was recorded. Audio is present for the Bash script image and PDF slide deck.

Husky Robot Demo (Second Video)

  • Link: Husky UR3 Gripper Demo
  • URL: https://drive.google.com/file/d/1FVhyBrrrvM0TzXG092dVYTzzvB7eGf9Y/view?usp=sharing
  • Contents:
    • Husky robot as mobile base
    • UR3 arm with Robotis Gripper
    • Local and global navigation
    • Bash script to launch all files
    • Controllers correctly launched

2. Assignment 4 Part 1 Slide Deck PDF

Primary Resource

  • Google Drive: Slide Deck PDF
  • URL: https://drive.google.com/file/d/1ohlPm3fGtu99IuSKNHaQ0uCQNHpwxsMg/view?usp=sharing

💻 GitHub Repository

Official Repository

  • URL: https://github.com/kulbir-ahluwalia/husky_ur3_simulator
  • Branch: Assignment 4 - Part 1
  • Contents:
    • Complete ROS2 package structure
    • Launch files for Gazebo simulation
    • Controller configurations
    • URDF/Xacro files for robot description
    • Example gripper commands

Key Files in Repository

husky_ur3_simulator/
├── launch/
│   ├── gazebo_sim.launch.py
│   ├── controllers.launch.py
│   └── teleop.launch.py
├── config/
│   ├── controllers.yaml
│   └── ros_gz_bridge.yaml
├── urdf/
│   ├── husky.urdf
│   ├── ur3.urdf
│   └── gripper.urdf
└── scripts/
    └── gripper_controller.py

🚀 Bash Script for Consistent ROS2 Launches

Complete Example Script

Save this as example_bash_script_for_consistent_ros_launch.sh:

#!/bin/bash
# Example Bash Script for Consistent ROS 2 Launch
# CS498GC Mobile Robotics - Assignment 4
# Adapted from ROS 1 Noetic to ROS 2 Jazzy/Humble
# Date: 2025-10-29

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m' # No Color

# ROS 2 workspace paths
ROS_DISTRO="jazzy"  # Change to "humble" if using ROS 2 Humble
ROS_WS="$HOME/ros2_ws"

echo -e "${GREEN}Starting ROS 2 Assignment 4 Launch Sequence...${NC}"

# Check and deactivate conda if active
if [ ! -z "$CONDA_PREFIX" ]; then
    echo -e "${YELLOW}Deactivating conda environment...${NC}"
    conda deactivate 2>/dev/null || true
fi

# STEP 1: Opens up a terminal window 1 - Gazebo Simulation
echo -e "${GREEN}Step 1: Launching Gazebo simulation with Husky + UR3 + Gripper...${NC}"
gnome-terminal -- bash -c "source /opt/ros/${ROS_DISTRO}/setup.bash && \
    source ${ROS_WS}/install/setup.bash && \
    ros2 launch husky_ur3_simulation gazebo_sim.launch.py; \
    exec bash"
sleep 5

# STEP 2: Opens a new Terminal window 2 - Robot State Publisher & Controllers
echo -e "${GREEN}Step 2: Launching robot state publisher and controllers...${NC}"
gnome-terminal -- bash -c "source /opt/ros/${ROS_DISTRO}/setup.bash && \
    source ${ROS_WS}/install/setup.bash && \
    ros2 launch husky_ur3_simulation controllers.launch.py; \
    exec bash"
sleep 3

# STEP 3: Opens a new Terminal window 3 - Teleoperation
echo -e "${GREEN}Step 3: Launching teleoperation for mobile base...${NC}"
gnome-terminal -- bash -c "source /opt/ros/${ROS_DISTRO}/setup.bash && \
    source ${ROS_WS}/install/setup.bash && \
    ros2 run teleop_twist_keyboard teleop_twist_keyboard; \
    exec bash"
sleep 3

# STEP 4: Opens a new Terminal window 4 - Gripper Controller
echo -e "${GREEN}Step 4: Launching gripper controller...${NC}"
gnome-terminal -- bash -c "source /opt/ros/${ROS_DISTRO}/setup.bash && \
    source ${ROS_WS}/install/setup.bash && \
    ros2 run husky_ur3_simulation gripper_controller; \
    exec bash"
sleep 3

# STEP 5: Opens a new Terminal window 5 - ROS 2 Bag Recording (commented out by default)
echo -e "${YELLOW}Step 5: Recording setup (uncomment to enable)...${NC}"
# gnome-terminal -- bash -c "source /opt/ros/${ROS_DISTRO}/setup.bash && \
#     source ${ROS_WS}/install/setup.bash && \
#     ros2 bag record -a -o assignment4_recording --max-bag-duration 30; \
#     exec bash"
# sleep 3

# STEP 6: Opens a new Terminal window 6 - MoveIt2 (for Part B)
echo -e "${YELLOW}Step 6: MoveIt2 setup for Part B (commented out)...${NC}"
# gnome-terminal -- bash -c "source /opt/ros/${ROS_DISTRO}/setup.bash && \
#     source ${ROS_WS}/install/setup.bash && \
#     ros2 launch husky_ur3_moveit_config move_group.launch.py; \
#     exec bash"
# sleep 3

# STEP 7: Opens a new Terminal window 7 - Navigation Stack (for Part B)
echo -e "${YELLOW}Step 7: Navigation stack for Part B (commented out)...${NC}"
# gnome-terminal -- bash -c "source /opt/ros/${ROS_DISTRO}/setup.bash && \
#     source ${ROS_WS}/install/setup.bash && \
#     ros2 launch nav2_bringup navigation_launch.py use_sim_time:=true; \
#     exec bash"
# sleep 3

# STEP 8: Opens a monitoring terminal - Check topics
echo -e "${GREEN}Step 8: Opening monitoring terminal for topic verification...${NC}"
gnome-terminal -- bash -c "source /opt/ros/${ROS_DISTRO}/setup.bash && \
    source ${ROS_WS}/install/setup.bash && \
    echo 'Waiting for topics...' && sleep 5 && \
    echo '=== Active Topics ===' && \
    ros2 topic list && \
    echo '' && \
    echo '=== Topic Frequencies ===' && \
    timeout 5 ros2 topic hz /odom & \
    timeout 5 ros2 topic hz /imu & \
    timeout 5 ros2 topic hz /scan & \
    wait && \
    echo '' && \
    echo 'Press Enter to continue...' && \
    read && \
    exec bash"

echo -e "${GREEN}===========================================${NC}"
echo -e "${GREEN}All terminals launched successfully!${NC}"
echo -e "${GREEN}===========================================${NC}"
echo ""
echo -e "${YELLOW}Terminal Windows:${NC}"
echo "  1. Gazebo Simulation"
echo "  2. Controllers"
echo "  3. Teleoperation (use keys to move robot)"
echo "  4. Gripper Controller"
echo "  8. Monitoring Terminal"
echo ""
echo -e "${YELLOW}Key Commands:${NC}"
echo "  Teleoperation: Use arrow keys, i/k for forward/back"
echo "  Gripper Open:  ros2 topic pub -1 /rh_p12_rn_position/command std_msgs/msg/Float64 '{data: 0.0}'"
echo "  Gripper Close: ros2 topic pub -1 /rh_p12_rn_position/command std_msgs/msg/Float64 '{data: 1.05}'"
echo ""
echo -e "${YELLOW}To record rosbag (30 seconds):${NC}"
echo "  ros2 bag record -a -o assignment4_netid --max-bag-duration 30"
echo ""
echo -e "${GREEN}Script completed. Check all terminal windows for errors.${NC}"

Script Features

Your bash script automatically launches:

  1. Gazebo simulation with Husky + UR3 + Gripper
  2. Controllers for robot control
  3. Teleoperation for mobile base control
  4. Gripper controller
  5. Monitoring terminal to verify all topics

To Run the Script

cd /your_directory/demo_assignment4_part1/
chmod +x ./example_bash_script_for_consistent_ros_launch.sh
./example_bash_script_for_consistent_ros_launch.sh

The script will:

  • Open multiple terminal windows
  • Provide colored status messages to track the launch sequence
  • Include corrected gripper commands (0.0 for open, 1.05 for close)

📋 Deliverables Checklist

Part 1 Requirements (25 points + 10 bonus)

✅ Rosbag Recording (30 seconds)

ros2 bag record -a -o assignment4_[netID] --max-bag-duration 30

Required Topics:

  • /cmd_vel - Velocity commands
  • /odom - Odometry (50 Hz)
  • /joint_states - All joint positions
  • /imu - IMU data (100 Hz)
  • /scan - Laser scan (10 Hz)
  • /gripper_position_controller/command - Gripper commands

✅ Screen Recording (30 seconds)

  • 10 seconds: Mobile base movement (forward, backward, turn)
  • 20 seconds: Gripper demonstration (open and close)
  • Format: MP4 or MOV
  • Tool: OBS Studio or QuickTime

✅ Submission Format

  1. Create folder: assignment4_part1_[netID]/
  2. Include files:
    • rosbag/ - Contains recorded bag file
    • screen_recording.mp4 - Screen capture
    • README.txt - Brief description

Part 2 Requirements (75 points)

  • MoveIt2 integration
  • Navigation stack implementation
  • Pick and place demonstration
  • Detailed documentation

🎯 Gripper Control Commands

Updated Commands (Corrected Values)

Open Gripper

ros2 topic pub -1 /rh_p12_rn_position/command std_msgs/msg/Float64 '{data: 0.0}'

Close Gripper

ros2 topic pub -1 /rh_p12_rn_position/command std_msgs/msg/Float64 '{data: 1.05}'

Visual Reference

Gripper Commands Example

🔧 Troubleshooting

Common Issues and Solutions

Qt5/GPU Errors

export QT_QPA_PLATFORM=xcb
export LIBGL_ALWAYS_SOFTWARE=1

Missing Topics

Check ros_gz_bridge configuration:

ros2 param get /ros_gz_bridge config_file

Transform Errors

ros2 run tf2_tools view_frames
evince frames.pdf

Controller Not Loading

ros2 control list_controllers
ros2 control load_controller gripper_position_controller
ros2 control set_controller_state gripper_position_controller active

📚 Additional Resources

  • Course Website: https://kulbir-singh-ahluwalia.com/cs498gc/fa25/
  • Assignment 4 Page: https://kulbir-singh-ahluwalia.com/cs498gc/fa25/assignments.html
  • Campuswire: For questions and discussions
  • Canvas: For grade tracking

Documentation

  • ROS2 Documentation: https://docs.ros.org/en/jazzy/
  • Gazebo Sim: https://gazebosim.org/docs
  • MoveIt2: https://moveit.picknik.ai/

Office Hours

  • TA Office Hours: Wednesdays 1:30-2:30 PM @ SC 4407
  • Special Sessions: Sept 17 & Oct 1 via Zoom

📝 Important Notes

From the Announcement (October 24, 2025)

“Prof Girish and I are both concerned that many students are not starting early enough for Assignment 4 which is the hands-on ROS semester long project for your learning and benefit.”

Key Points:

  • Start early to maximize learning
  • Attend office hours for help
  • Ask questions on Campuswire
  • Watch demo videos for guidance

Motivational Note

“We will showcase the Deliverable TEASER Video this Friday, Oct 24 in class, SC0216, 3:30pm, to motivate all students as to how thrilling it is to control a Mobile Manipulator robot in your own local setup!!”

📧 Contact

Teaching Assistant: Kulbir Singh Ahluwalia

  • Email: ksa5@illinois.edu
  • Website: https://kulbir-singh-ahluwalia.com/

Instructor: Professor Girish Chowdhary

  • Email: girishc@illinois.edu
  • Lab Website: http://daslab.illinois.edu

Last Updated: November 7, 2025