I don't know why I decided to put a Sharp IR (GP2Y0A21) in K-9. Probably because it's smaller than the HC-SR04 that I'm so much more used to. In any case, I got a general system assembled and decided to test it using essentially the same branching that I used on Maus. It seems to go into its obstacle avoidance routine at random. It definitely reacts when it "sees" something, but also often when there's nothing in front of it. What I'm wondering is could the "Analogness" of the sensor be what's killing me?