A lot of homeowners often find themselves in this situation but the problem is more of maintenance as opposed to malfunctions. If your robot seems to just pass on the floors and coming back to an empty bin, then there are a few parts you need to consider replacing.
If you have not changed your filters, maybe its time you consider buying a replacement because they get worn out very fast especially when used for daily cleaning. If you have just replaced the filters or you can’t get new filters, use compressed air to clean the entire filter system, and vacuum.
The brushes may also be the issue so if you haven’t replaced them in a while, it could be the main culprit. You can also use compressed air to clean it, this will at least boost its performance for a short while.
Another reason for dismal performance would be a dead battery. Remember, suction power highly depend on the battery so when it is less powerful, the suction power goes down. Consider replacing your battery if all the other solutions fail and most importantly if the battery shows signs of fading.