Save and retrieve data on the robot (Database)

Technical
1

Hi

I would like to save a list of data in the robot. Similar to a database (Example: SQLite). You would need around 4 columns and several records and then you would need to retrieve these values. I believe you can do something with JSON but I would like to know if anyone has already done something like this using JAVA and WPI? Another problem I see is the limitation of storage space, I don’t even know how this works in RoboRIO. I’ll wait, thank you.

2

I don’t know what/why you need a database.

I would look at the Preferences API, as it will persist data on a file in your Rio: Setting Robot Preferences — FIRST Robotics Competition documentation It would also put the data on NetworkTables, so you can tune it on the fly.

If you are insistent on using a database or something, remember the Rio is just a Linux PC (with a really old kernel). You can do file IO to read/write files to it. Just watch out you don’t fill the storage (you have hundreds of MBs on a Rio1).

1 Like
3

Hello.

Thanks Steve. I want to do some tests by saving points in the arena and also a trajectory taken by the robot. I will look into your suggestions. When I solve it I will also post it here. Thank you very much.

4

why not save your points to the drive-station. you will have far more flexibility that way.

5

While you can plug a USB flash drive in… any major read/write operations on the RIO are glacially slow. I’d recommend a co-processor for this or using your driver station.

6

Another option, you could use WpiLib logging for some of this. As long as the data could be on NetworkTables, you can log it quickly (see On-Robot Telemetry Recording Into Data Logs — FIRST Robotics Competition documentation). My team has used it for 2 years now, and it works well. AdvantageScope (which came with WpiLib this season) can view all the data recorded or live. We just stick in a flash drive to the Rio and it auto logs there.

You can also plot your current location and trajectories with it, see The Field2d Widget — FIRST Robotics Competition documentation. AdvantageScope even has a odometry tab that you can plot your robot on it.

7

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