Simulate ball following with PrintingMotion

  1. Open main.py. This file contains an example implementation of the image processor and motion classes. For this task in case of questions, ask an instructor.

  2. There should be a main loop that processes every camera frame and outputs the color information received by the camera.

  3. You should implement an object contour finding algorithm using tools provided by OpenCV to find the center coordinates for every green ball’s contours. Some hints can be found here: https://docs.opencv.org/4.x/d4/d73/tutorial_py_contours_begin.html

  4. Return the found coordinates in a structured way in case you need to extend the data being returned in the future. Remember that there can be multiple balls in the frame so you should return a list. Also consider how to sort the list of balls to find the best one to drive towards.TL;DR steps:

    • Create a new function that takes in the frame data and returns a list of found balls

    • In the function find the contours for all using OpenCV

    • (Optional: Do some filtering to reduce noise, like pixel-sized contours. It is best to filter data as soon as possible to reduce work being done on data you will throw away anyway)

    • Get the X and Y coordinates (and other data, if needed) for every contour. This is the data we will return.

    • Sort the data in a meaningful and consistent way. You should lock onto a single ball, not change the target every detection loop.

    • Check Useful links and other resources for an pseudo-code example.

    • Make sure you return all the processed data to the main loop.

  5. Use the return data in the main loop to find if there are any balls in the frame.

  6. If there are balls in the frame, find the largest ball and its coordinates. Take into consideration that the zero coordinates of the frame are in the upper left corner.

  7. Using these coordinates calculate the rotation for the robot to turn towards the ball. Use PrintingMotion and its move method print the direction the robot is turning. If the direction is opposite to what you expect, you can set the polarity variable to -1 to invert it. The default is 1.

  8. Write code so that the robot centers the ball horizontally. The robot should stop once a ball is in the center of the frame and turn towards the ball if it is at one of the edges of the frame. Don’t only use constant speeds since it leads to jerky motion. Try to implement a proportional system where the robot turns faster when the ball is further away from the center and slower when closer, stopping when centered. Consider using the width of the frame, the current position of the ball and the desired position of the ball in your calculations.

  9. Demo your solution to the instructors. Iterate on the solution in case deficiencies are brought up by instructors.

  10. If everything works, continue to the next task.