Yes and no.
The no part first: Mars 2020 had sensors and effectors attached to the non-important parts of your diagram, many of which had various degrees of smarts.
- Star trackers are very sophisticated cameras. The have their own computers that control mode (e.g., lost in space versus locked) and that perform pattern matching on an self-contained star map. The output of a star tracker is orientation (or attitude). That makes using a star tracker easy as pie for the main flight computer. The star tracker was not attached to the rover. It was ejected at some point during entry, descent, and landing.
- Mars 2020 had another camera that was on the critical path for landing and was not attached to the rover. Cameras are also sophisticated instruments (but not nearly as sophisticated as a star tracker), and typically have microcontrollers. This lander camera (LCAM) took commands from the Vision Compute Element (VCE) and sent images to the VCE.
- Modern thrusters take the amount of time they are commanded to be on over a smallish period of time. This means that the thrusters have to have their own microcontrollers and clocks with a time step that is considerably smaller than the time step used by the main computer's guidance, navigation, and control (GN&C) software.
- One set of equipment that was redundant on the Mars 2020 vehicle was the communications system. The rover has its own communication system, and so did the vehicle as a whole. The rover's communications equipment was enshrouded until the shells were ejected. Modern communications systems also have embedded microcontrollers and precision clocks.
- Another set of equipment that was redundant on the Mars 2020 vehicle were its Inertial Measurement Units (IMUs). The descent element had a set of IMUs distinct from those on the rover. An IMU is a smart sensor and is critical for navigation. IMUs, like thrusters, operate at fast rates. The non-gravitational accelerations output by an IMU are measurements taken at very fast rates that are accumulated by the IMU to generate the slower rate data to the main flight computer.
- The VCE mentioned above was a computer system distinct from the main Rover Compute Element (RCE). The VCE had its own flight hardware, firmware, and software. The heart of the VCE was a RAD750, the same kind of computer used by the RCE. However, since the VCE was on the rover, it is fair to say that the rover drove Mars 2020 from entry interface on.
- Finally, JPL drove the vehicle to Mars. Mars 2020 did not know where it was until shortly before the onset of entry, descent, and landing. While it is impractical to remotely drive a Mars rover on a minute by minute basis, that imperative did not exist during the cruise phase. All that the vehicle had to do during the cruise phase was to respond to infrequent commands from JPL to perform trajectory correct maneuvers.
Finally, the yes part: During entry, descent, and landing (EDL), it was without a doubt the rover's computers that controlled operations. The terrain recognition computer, the VCE, was on the rover, as was the rover's main flight computer, which performed EDL guidance, navigation, and control.