I had dissected mine. Here are what the sensors are about:
1.) Yes, there is a scale at the bottom (false bottom). There is also a weight sensor under the food dish. They were used to determine if food was dispensed and how much.
2.) There is an an IR eye on the food hopper to detect food level (they never enabled this which is why we never got notifications).
3.) There is also an optical encoder/interrupter sensor designed to ensure the motor is actually spinning and doesn't get jammed (mine would jam all the time, part of why I threw it away)
