The problem
In the first prototypes, the camera was placed at the top of a pole independent from the base of Babot. This location allowed easy recognition of the ball’s position. The camera looked down and the ball appeared to the camera on the white background of the plate. This made the detection of the color of the ball very simple but there were several counterparts. The pole had to be very tall for the camera to be at the right distance from the plate and well centered. Consequently, the pole was very sensitive to vibration and this caused the camera to move slightly, which disturbed Babot. It was impossible to move Babot when it was on, otherwise it made the pole move and nothing worked anymore because of the movement of the camera. Another problem with this pole was that it took a lot of space and was fragile so it made Babot difficult to carry.
The solution
The chosen solution was to place the camera in Babot’s base to make the whole product much more compact. For the ball to be visible to the camera, the cardboard plate has been replaced by a frosted acrylic plate. Thanks to this treatment of the acrylic the ball seems clear on the camera only when it is very close or when it touches the plate. Unlike the first prototypes the background of the ball is not fixed, the camera sees the ball but also what is happening above it which makes the detection of its position much more complicated.
Another challenge related to this location of the camera was to resize the dimensions of the three arms so that they did not fit too much in the field of view of the camera. No matter where the ball is on the plate, it will never be hidden by one of Babot’s arms.