For my mechatronics project, we decided to create a robotic goalie, like we have seen in a few videos. I accomplished this by using a camera and OpenCV, a computer vision library for Python to track the ball and move a servo motor to an angle calibrated through experimentation based on what "grid square" the ball was in.

Earlier prototypes I made attempted to use 2 cameras to triangulate the ball and note its position in 3d space and draw a line between the current point and previous point of the ball and determine if it will intercept the goal. If it does, it moves the servo to the angle required to intercept the prediction. While this method occasionally worked, it was overall inconsistent for me and I went with the simpler grid method.

More detail about the steps in the design process are below.

Enclosure and Hardware

I designed this sheet metal enclosure for the box to house the electronics. It has mounting holes so it can be screwed into wood, or you can put tent stakes in them to hold it in the ground for outdoor use.  It also has a handle to make it easily portable since we had to move it a lot. They ended up too uncomfortable for holding directly, but were still good for mounting a grip as seen below in the first picture on the left.

Software

The software was made in Python using a few key libraries:

• Pyfirmata 2

  • Allows Python to talk to the Arduino

• OpenCV

  • A computer vision library that allows tracking of the ball

• Pickle

  • Saves and loads matrices that contain the "models" trained based on the grid size and camera position

• Numpy

  • Allows for 3D math, used for the dual camera setup.