[GeeTwo]

We have done a number of projects (most notably our air cannon) with arduino controls. They are a great way to control a robot on a much smaller budget that using a roboRIO. They interface easily with all of the PWM-based motor controllers, as well as the spike relay, and (through 12V relay modules) pneumatic solenoids, LEDs, and a wide variety of sensors. That is, they are a great low-cost replacement for the roboRIO in many applications where the RIO is a bit of overkill.

While it is certainly possible to communicate between arduino and cRIO/roboRIO computers using USB, serial I/O, I²C, and/or SPI, we have not found enough reason to justify the effort. This is because the thing that arduinos do so well is to provide a bunch of analog inputs, digital I/Os, and PWM outputs; these are all things which the RIOs natively do in sufficient quantity (and speed) for our needs.

We have successfully used raspberry pi as a vision processor on FRC competition robots. That is, we connect the camera directly to the pi (or on network in 2012-2014), and send data packets consisting of just a handful of numbers to the robot telling it where the target is located (header/sync, x, y, width, height). Offloading the vision processing to a device adjacent to the camera definitely reduces the required wireless network bandwidth and/or the CPU load on the RIO. (and vs or is based on your alternate solution.)

I guess the main thing to know as to how or if to integrate an arduino and a roboRIO boils down to the generic engineering question: what problem are you trying to solve?