When it comes to electrical components, specifically the RoboRio, are you allowed to use one from a robot from a previous year?
Yes, RoboRIOs can (and are expected to) be used from year to year. Make sure to read the rules regarding what modifications can be made to parts prior to kickoff.
All electrical components can be reused so long as they are returned to COTs status(how you bought them) meaning you can’t just take out your electrical board from last year and reuse it. However, if you were to unwire everything then you can reuse components.
For motors, motor controllers, and any other component that might have connectors attached keep R14 D in mind and for batteries R14 C
R14. Physical ROBOT elements created before Kickoff are not permitted. Exceptions are:
A. OPERATOR CONSOLE,
B. BUMPERS (a protective assembly designed to attach to the exterior of the ROBOT and constructed as specified in Section 8.5 Bumper Rules),
C. battery assemblies per R05-B,
D. FABRICATED ITEMS consisting of one COTS electrical device (e.g. a motor or motor controller) and attached components associated with any of the following modifications:
I. Wires modified to facilitate connection to a ROBOT (including removal of existing connectors)
II.Connectors and any materials to secure and insulate those connectors added
III.Motor shafts modified and/or gears, pulleys, or sprockets added
The intro to Section 8.1 and R14(D) have most of what you’re looking for. It’s also a good idea to just search through the rules for all occurrences of “COTS” for some of the nuances. Note that R14(D) does not apply to COTS items per se as they are not FABRICATED ITEMS, but specifies how much you can tweak it before kickoff and still use it on your robot.