I’m just analyzing sidestick inputs from a flight simulator study with manual flying (raw data). On Airbus aircraft you can either do one-dimensional/separate or two-dimensional/combined inputs on the two-dimensional sidestick.
Some flight trainers say that a pilot should separate the inputs on both axes, doing only one-dimensional inputs, i.e. pitch or roll inputs, but not at the same time. One possible reason for separating both axes might be a higher control accuracy when manipulation one axis only.
I’m looking for documents, reasons, literature for or against this practice. Does anyone know such documents or know some reasons for or against the separation of axes?
Dear Mr. Haslbeck,
as you know, it was always our ergonomic "religious conviction" that the dimensionality of the task with the dimensionality of the control element should agree (an example is the separate control of the north - south / the west - east direction on a map by 2 separate control elements which is to be used clearly more difficult as the identical task with a touchpad or a joystick). Presently to me no scientific investigations is known to this question for the control of airplanes. With the attempt to steer the longitudinal and transversal dynamics of a vehicle by means of a joystick, however, appeared that because of the different dynamics (time constants) of the vehicle in transverse direction and longitudinal direction a separation absolutely makes sense. By a realization of such a control in a roadworthy vehicle, Eckstein has laid out for example, the joystick in transverse direction as an active control element and in longitudinal direction as an isometric control element. By the transmission of this knowledge on the airplane would be to be investigated from my view first, whether there exist important dynamics differences between lateral and upward/down movement. If these are in the identical order of magnitude, the two-dimensional control element is to be preferred according to my images.
This would be highly impractical in a flight control, speaking from the perspective of a pilot, as positive aircraft control constantly requires dynamic, varied control inputs.
I do not understand David's answer completely. Just because in an airplane a constant feedback of the dynamics is necessary for a successful operating, according to my ergonomic images the active control element (there is an haptic feedback about the dynamic effects of the airplane) would be the given means of the choice. However, after my knowledge such a control element nowhere is in application. The traditional mechanical control element supplies such haptic feedbacks, like they would be realised by an active operating element, now by the electronic way.
Thank you for this discussion. However, my question addresses a more practical problem of manual control of an aircraft. I guess modern fly-by-wire aircraft like most of the Airbus types provide quite good flying and handling qualities. A major point of criticism is that the Airbus sidesticks do not provide haptical feedback.
But as mentioned above my focus is on more practical questions:
Why should pilots in Airbus aircraft control both axes (roll and pitch) at the same time (combined inputs) or separate their inputs? What do we know in terms of precision, workload etc?
Wow, it's been a long time since I asked this question. Now I published an articel with this kind of analysis - just check my latest publication 'Stirring the Pot'. I could differentiate between one dimensional and two dimensional sidestick inputs in airline pilots. But I still have the feeling, that there is not too much other literature analyzing this behavior.
Wow, it's been a long time since I asked this question. Now I published an articel with this kind of analysis - just check my latest publication "Stirring the Pot". I could differentiate between one dimensional and two dimensional sidestick inputs in airline pilots. But I still have the feeling, that there is not too much other literature analyzing this behavior.
Wow, it's been a long time since I asked this question. Now I published an articel with this kind of analysis, just check my latest publication "Stirring the Pot". I could differentiate between one dimensional and two dimensional sidestick inputs in airline pilots. But I still have the feeling, that there is not too much other literature analyzing this behavior.
The answer is actually quite simple: the task of flying is even three-dimensional, because the pilot can determine speed (= location in the longitudinal direction), turn flight (= position in the lateral direction) and height (= position in the vertical direction). Due to the characteristics of the aircraft and the aerodynamics these 3 directions are coupled with each other (this is not unlike the car, with which a two-dimensional task can be fulfilled - position in the longitudinal direction and position in the transverse direction on the road surface - and where also the movement in longitudinal and transverse directions due to the driving physics are coupled together).
In a certain manner independent of definition of the task is the type of technical realization: with flying by means of a joke or a two-dimensional joystick, at least the task can be met in transverse and high direction by a single control element, whereas speed is separately influenced by control of the engines. From an ergonomic point of view, ideally the dimensionality of the control element should match the dimensionality of the task.
In order to answer your question, it is necessary to distinguish between the dimensionality of the task and the dimensionality of the influence of the respective vehicle, which, due to the technical realization, do not have to coincide with each other.
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