This contains the design files for the various electronic modules that make up the robot. The original development was done with Eagle Version 7 since it was the last 'free' version of Eagle. More recent versions are likely to be developed in KiCad since it is free, open source, unconstrained and multiplatform.
You are only likely to need to look in here if you want to modify existing modules or create your own. Either Eagle or KiCad can be used for new development.
If you only want the PDF schematics, gerber files, renders of the boards or a Bill Of Materials, look in the hardware section of the repository.
NOTE that the actual sensor devices used, and their related component values are nominal suggestions and you are free to make changes as you wish. The values shown are nominal and are likely to need adjustment for your specific build.