Being an all around Scraper seems to work for us. Originally, we had a "claw" that would knock down 5 rows of bins and would allow us to stack. We couldn't make weight, so the claw disappeared. The arm mounted on a turret has proven to be a very good defensive strategy. It allows us to knock down at least 3 rows and "stiff arm" 'bots coming up the ramp. We haven't intentionally knocked a high center bot over. But if they try driving up the ramp, and our arm is down, over they will go. The arm also allows us to reach over other robots protecting a stack.
Having a fast, reliable Auton mode is very important. He who knocks bins in their zone first, has a big advantage. Especially if you can prevent the other team from stacking. We are consistantly to the bins in 3.2 seconds.
KOTH 'bots are tough, but they must have an effective method for staying on the ramp. Having a machine that is versitale seems to be a better strategy this year. Good drivers are extremely important too!!! Helps if you have a second robot of similar design to practice with.
