I love it when one can find a way to simplify things. Multi-deck robots are inherently cool (there was a great example of one at the FRR meeting), but mine was looking like a weird Star Trek era pagoda on wheels -- with clearance problems, no room for the fire suppression equipment or for routing wires, and the controller in an odd place. That's because there's a front servo with a crab-claw-like ranger array taking up tons of space, and a rear servo with a flame sensor in the form of a giant flashlight reflector taking up more space.
Why put the flame sensor on a servo? To avoid DC motor noise and ensure precise control of the scan. At slower speeds pulse width modulation is imprecise. On the other hand, with a servo, once you find the candle it's hard to point the robot body properly unless your robot uses encoders. Even so it is another challenge.
The answer: repeated, short bursts of high duty cycle to the motors, reading the flame sensor in between. Result: a granular, smooth scan. Find the candle, then drive forward. Simple. So I can ditch the flame servo and solve one clearance problem, and mount the flame sensor on the 3rd deck.
With Servo 2 gone, the controller has a better home, wiring is simplified, and now the robot is modular. Swap on a purpose-built top deck for specific tasks.