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The University of New Mexico

Mobile Motion Capture Testbed

Funding: MAST-CTA

Students: Shakeeb Ahmad, Joseph Kloeppel, Jasmin Regalado

Introduction

miniROaCH is a small-scale, affordable, and portable multi-vehicle robotic platform, capable of running Linux, and hence Robot Operating System (ROS) on-board. The purpose of this research is to simulate and implement a small-scale swarm testbed based on these miniROaCHes. Developing a swarm testbed can be difficult in terms of robot localization. The proposed testbed aims to tackle this difficult issue by utilizing an aerial vehicle used to monitor and publish the locations and orientations of the swarm’s ground agents. The testbed consists of one quadrotor and multiple crawler robots. The team plans to build a mobile motion capture system so that experiments can be done both indoors and outdoors. The system is able to precisely estimate the poses of multiple ground robots with respect to the absolute world frame. A quadrotor UAV with a downward-facing camera is used to detect the relative poses of the ground robots in its field of view. The poses of each ground robot are ultimately transformed into the world frame through proper transformation calculations. The pose of the quadrotor is measured with respect to the world frame for the transformation.

Approach

The research is divided mainly into two parts:

  1. Simulation: Gazebo is used to create an environment with a hovering quadrotor, miniROaCH ground robot models, and a camera mounted beneath the quadrotor. AprilTags are used on the ground robots to detect their unique positions relative to the quadrotor frame which is ultimately transformed into the world frame.
  2. Practical implementation of the system: A tripod mount with a camera facing downwards is used to measure the relative poses of the miniROaCHes on the tabletop. An AprilTag package for ROS is used to decode the AprilTags posted on the ground robots. Once the transform tree in ROS is available, a simple swarm control algorithm is demonstrated with the system.

Tools

  1. ROS (packages : rotors_simulator, apriltags_ros etc)
  2. Rviz and Gazebo
  3. Raspberry Pi Zero
  4. 5 Kamigami Dash Robots (MARHES custom build)
  5. Tripod and camera mount
  6. USB Camera