Are You Using A Camera To Align Their Shooter?

[Jaci]

We're using a Kinect this year for our vision processing, connected to a coprocessor running Freenect and OpenCV.

The Kinect uses an IR stream to find depth, however you can also view the IR stream Raw, which is extremely useful, as it means we don't need to have a big green LED on our robot's camera.

Our coprocessor (originally the Pine64, but changed to the raspberry pi because of driver support in libusb) finds the contours and bounding boxes of the high goal target. These values are sent to the RoboRIO via regular sockets. A single frame of data takes up only 32 bytes per target, which means we never run out of bandwidth. All this code is in C/C++.

Instead of doing some (unreliable) math to find the angle and distance to the target, we're just using a PID controller with the error set to the deviation between the centre of the bounding box and the centre of the frame to align. For distance, we're just using a lookup table with the distance of the target from the bottom of the frame in pixels. Calculating Distance and Angle is an unnecessary step and just complicates things.

While a target is in view, our flywheels will passively spin up to the appropriate speed to avoid taking time to spinup when we're ready to take a shot. This means the shot it taken almost instantly when I hit the 'shoot' button on the joystick.

Our vision code is written in C/C++ and our RoboRIO code is written in Java/Kotlin.