Cup Tower Stacking with Baxter

Baxter stacks tower of cups with Moveit, Apriltag, and OpenCV

Project Overview

*3 Cups Tower Demo*

This is a ROS project developed as part of the ME495 - Embedded Systems in Robotics course at Northwestern University.

The goal of this project is to use the BAXTER robot to build a “HUGE” tower from plastic cups.

My role in this project was image processing using AprilTags. I implemented AprilTag detection using the apriltag_ros wrapper package and published the cups’ transformations so that the Baxter would detect and keep track of the locations of the cups.

Demonstration

10 Cups Tower

*10 Cups Tower Demonstration*

6 Cups Tower

*6 Cups Tower Demonstration*

6 Cups Sorting

*6 Cups Sorting Demonstration*

Project Details

Gazebo Simulation

*Gazebo Simulation Environment*

• Baxter Simulator
• Tool utilized to test code without a real robot
• Get the position of the cups with get_model_state service
• Set cup pose with set_model_state

Rviz

*Rviz Visualization*

• MoveIt to set the planning scene and Rviz visualizer
• Set the positions of the cups and tables
• Add objects to the scene
• Return information about the scene

Robot Control

*Robot Control Interface*

Let one hand first place what it’s grabbing, then let the other hand grab the next cup to place.

Computer Vision

*Computer Vision Setup*

*Computer Vision Results*

• We used apriltag_ros, which is a ROS wrapper of the AprilTag, to get x, y, z positions of the cups.
• We mainly used Baxter’s right-hand camera for tag detection, but we provided options to use the left camera or the head camera.
• simulator.py, which is a MoveIt Python API, converts tf data to x, y, z positions and adds positions and visual cylinders that represent cups to the scene, which can be seen in Rviz.
• arm_control nodes use those positions for Baxter’s tasks of sorting or building cups.

Project Team Members

• Dimitrios Chamzas
• Dong Ho Kang
• Yuxiao Lai
• Gabrielle Wink