Boeing FBW Controller Backdrive Objective
The objective behind pilot controller backdrive on the Boeing airplanes is to move the controllers as they would need to be moved by the pilot to achieve the same response as is being delivered by the autopilot were the autopilot disconnected and the pilot flying manually. On non-FBW models this indicates the position of the associated surfaces. That is not the case on FBW models where surface position is defined by maneuver demand, stability augmentation control laws.
One outcome of this approach is that only minimal airplane transient will result if at any time the crew grabs the controllers and disconnects the autopilot while maintaining controller position.