The issue appears to be in your use of:
Code:
Connector.openOutputStream(filename);
The stack trace is complaining that the filename value you provided is an illegal argument (bad parameter) for this method call. You passed in a value of "PrewinterRobotData". I'm guessing you wanted the Connector class to use a file named "PrewinterRobotData". It looks like the Connector class expects the string to be in the form of a URI (like a web page address).
I'm not familiar with the Connector class you are using, but you could try changing your filename value to: "file:///PrewinterRobotData" (a URI which specifies a file on the cRIO file system).
NOTE: If this works, you will need to ftp to your cRIO to download the file when you want to look at it's contents.
Hope that helps,
Paul