Integrator ?

[SUB320]

Hi,
Just doing the transition to the Airbus 320, and I cannot understand what the integrator is and what/how does it function. Cannot find any information in the FCOM except the quote below.Would appreciate any experienced pilot/engineer on the Airbus fleet to explain .

"With the horizontal stabilizer jammed, control is much easier than it is on a conventional aircraft, because the integrator holds the elevator required to maintain the 1g flight path. The control laws remain normal to touchdown."

Thank you
:hmm:

[barit1]

Integration in calculus is a means of finding the area under a curve.

Inasmuch as the Airbus FBW uses computer calculus to provide control loops for artificial stability, IMHO the "integrator" referred to here is a computer math model controlling the elevator. In this case it may be integrating pitch over a period of time to seek zero pitch change.

But hey, I've been wrong before... :uhoh:

[Paris Hilton]

* Integrator--Circuit in an FBW flight control system that reduces response errors over time. It "remembers" the pilot's command and continues to move the control surfaces until the desired response is achieved and no further "error signal" is present.

Integrators remember the pilot's request as of some time ago, which may differ significantly from the pilot's instantaneous request during rapid control inputs. This may cause system lag and instability.

To provide immediate response to pilot input, the computer provides a direct path to the elevator via the proportional line (called the "feed forward gain" in the B-777). For precision over time, an integrator produces a control surface command until the feedback signal is equal to the pilot's command signal.
Pure integral control, or too much integrator gain (K), causes excessive lag in the aircraft response, hence the use of the proportional circuit. This arrangement, called "proportional plus integral" control, is found in most fly-by-wire designs, including the B-777 and the A320.
In a block diagram, "1/s" or "K/s" denotes an integrator, the "K" indicating some gain value. FBW engineers must "tune" the integrator gain to prevent excessive lag.
Lag causes delay in changing directions--for example, nose-up to nose-down, which is a classic cause of pilot-involved oscillation, or PIO. Engineers can mathematically analyze control laws for such instabilities.

[barit1]

See, I told you I was wrong :eek:

[SUB320]

Thanks , information much appreciated. :ok: :ok: