Powering sub-sytems on a robot with a single battery
The issue with using linear regulators (LM78xx) is that each regulator dissipates as heat the power represented by current to the load x Voltage dropped by regulator. 

For at least the servo motors mentioned, this would be substantial: 6 x Servo Current x (12 - 5). For one thing this will need a good heat sink on the LM7805, for another, the battery will discharge quickly as a lot of power is just being wasted as heat.

A scheme that could work is to use DC-DC buck regulators powered from the 12 Volt battery for the 9 Volt camera and the 5 Volt servo motors, and (optionally, if needed) a linear regulator instead of a buck regulator, from the 9 Volt camera rail, for a clean 5 Volt supply to the microcontroller. 

Also, one would use separate 5 Volt regulators for the microcontroller supply rail and the servo supply rail, to avoid EMI from the servo motors messing with the microcontroller.

Buck or switching regulators do not waste as much power or generate as much heat as linear regulators, they have efficiency in the 80% to 92% range. Thus batteries would last longer too.

There are integrated buck regulators available as drop-in replacements for the 78xx series. See the Murata OKI-78SR series as one option, there are others as well: