Vision and Object Tracking
Why we need Vision
Almost every year FIRST puts retroreflective markers on key locations around the field, retroreflective tape is a material that reflects light back in the direction it came from like what's on high vis clothing. By putting powerful led's next to a camera the tape reflects a lot of light back to the camera and appears very bright. By lowering the camera's exposure almost nothing else is visible and we can search for blobs of the same colour as the led's to find where the tape is. Greed led's are used because there is usually not much green on the field to get confused with. This technique has been used for many years in FRC and so some teams have developed a product called a limelight which is basically a raspberry pi compute unit, bright green led's and a camera all in one unit.
in 2023 FIRST will be putting apriltags on the field.
The team has also used similar colour blob techniques to what is used for retroreflective tape to detect game pieces like the yellow cubes from 2018. If a game piece has a large distinct and high contrast colour this is likely the easiest solution to locating it.
In the past FIRST has also sometimes included high contrast tape markers on the floor at key locations on the field, these can be detected with reflectance or colour sensors and used to line up or localize. In 2019 we used a array of reflectance sensors to allow the robot to line up automatically.