What does rudder input control in normal law in an A320? I understand form documentation that in normal law, pedal input is not necessary to keep coordinated flight. It is merely said that using the pedals is not necessary. Later in the documentation it is said that the law for the yaw axis is either normal, alternate or direct (depending on the condition). For the normal law, automatic functions are implemented (yaw damping, coordinated flight). What happens when the pilot provides a non-neutral command on the pedals? Such information is well documented for pitch an roll control (command of load factor and roll rate), but not for yaw.

On the A380, the documentation states that, "A pedal deflection results in a proportional sideslip and bank angle". I found no such precision for the A320, but it seems reasonable to assume the pedals command a sideslip angle.

In normal and alternate law on a A320, do the pedals command a sideslip? If not, what do they command?
You are correct. On all Airbus FBW aircraft, the rudder pedals normally control the sideslip angle, beta. See this presentation for a source, slides 3, 5-6.

As a note, on pre-A345/A346 models, the rudder pedals are mechanically connected to the rudder. However, the FBW system adds in an additional input, via the yaw damper servos, to drive the rudder to the position the FBW control loops want.

Additional details can be found in Advances In Aircraft Flight Control, M. B. Tischer, page 90:


  Finally, it was decided that the rudder pedals would command a combination of sideslip and roll angle to restore some of the conventional aircraft behavior.


Figure 5 shows that the rudder command is a gain-scheduled proportional control based on sideslip, yaw rate, roll rate, and roll angle. The gain scheduling is based on airspeed and high-lift configuration.