I've modified to cleanFloor() to go back to the charging station once it's done cleaning.
I used Sue's ShortestPath class and it seems to work so thanks for the fix Sue, because just minutes before you pushed the update, it wasn't working for me.
Once it reaches the homeTile, I also have it recharge.

FYI: To get this to work, I temporarily changed MAX_BATTERY_CAPACITY = 100