One wall on the deep end of my pool has a negative edge wall that overflows over 1 foot wide "coping" into a collection trough about 4 feet below the top of the negative edge. I would like to to get a robot but am worried that the robot will climb the wall, start cleaning the 1 foot flat area and then tumble over the negative edge. Do robots do this? Kind of like cleaning the very top of the stairs I guess. I hope this is clear, if not, I can post a pic of what I'm talking about later. I don't want to invest in a robot if it will fall over the negative edge and break. Thanks in advance.