Cosi119a

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### Introduction

* This final programming assignment pulls together what we've learned up to now
* You will practice detecting fiducials and using them to do simple navigation
* You will have to make sure the camera sees the fiducial and then navigates to it
* The task seems quite simple but it requires mastery of several aspects of Robotics at once
* What you learn here will very likely be directly applicable to your projects.
* Note that this assignment will only be done IRL.

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### Expected preparation

* Remember that the Platform and BranBot robots are preconfigured for fiducials where as the turtlebots will need some packages installed.
* Before tackling the full assignment, experiment with the fiducials IRL interactively
* You have to write a test program that prints out information of the fiducial it sees
* You can choose to use OpenCV's fiducial algorithms by themselves or use the aruco_detect layer
* Re-read PRR Chapter 2 to refresh your memory of coordinates and tfs/

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### Additional references and resources

* [Ubiquity Robotics Fiducial Follow](https://github.com/UbiquityRobotics/demos/tree/master/fiducial_follow)
* [Ubiquity Robotics Fiducials](https://learn.ubiquityrobotics.com/fiducials)
* More generic CV: [OpenCV aruco detection](https://docs.opencv.org/4.x/d5/dae/tutorial_aruco_detection.html) 
* ROS Oriented: [aruco_detect](http://wiki.ros.org/aruco_detect)
* [ROS Wiki tutorials on the tf2 package](http://wiki.ros.org/tf2/Tutorials).
* [This](https://www.rosroboticslearning.com/rigid-body-transformations) may help
   you understand transforms better.
* The [tf cheatsheet in the labnotebook](https://campusrover.github.io/labnotebook2/faq/tf/tf_cheatsheet/?h=cheat)

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### Requirements for the PA

* Setup
   * Four red blocks in a square with about 2m edges (you can tweak this if you need to)
   * Fiducial taped to each of the blocks, facing inwards
   * Robot in the center of the square
* roslaunch your package
   * The robot spins in place until it seems one (or more) fiducials
   * It drives slowly up to one, and returns to the center
   * And does it for the other three
`

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### Steps

1. Study and understand the `mapper.py` file.
2. Change the `fid_ids` parameter of the `mapper.py` file to match the ids of
   your fiducials.
3. Complete the `nav_real.py` file such that the robot:
   1. rotates in place to scan all the target fiducials; and
   2. moves to each target fiducial in turn.
4. Complete the `nav_sim.py` file such that the robot:
   1. rotates in place to scan all the target fiducials; and
   2. moves to each target fiducial in turn.

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### The Skeleton Code (Real)

1. `bringup` (onboard the robot)
2. `roslaunch fiducial_nav fiducials_real.launch` (on your vnc)
3. `rosrun rviz rviz` (on your vnc. Tune the RViz to visualize what you want.)
4. `rosrun fiducial_nav nav_real.py`

* [Sample Solution - IRL](https://www.youtube.com/watch?v=3K-Q4WguUSE&list=PLWp7_Yk4l1aPcMGxCCvqKCSwnkTBBInI3&index=78)

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### What to submit

* A correctly structured ROS package including
  * Nicely commented python source files
  * Readme how to run it
  * Appropriate launch file
* Video of your program running
  * IRL
  * Best to put the video on youtube and give the link
  * In your own voice, explain how the code works