The time delay which arises due to rate limiting in a control system has been identified as a contributing factor to the occurrence of pilot induced oscillations (PIO's). Recent discussions concerning PIO prevention measures have proposed the elimination of this time delay through an alternate control scheme. In response to this proposal, the SCARLET (Saturated Command And Rate Limited Elevator Time delay) project was initiated in order to study the effects of both the time delay and the elimination scheme on the handling qualities of a contemporary fly-by-wire aircraft. A flight experiment was carried out in 1992 using DLR's ATTAS In-Flight Simulator. The flight test included runs with two different control laws: a conventional control scheme and the alternate control scheme (ACS). Results of the experiment demonstrated both the negative effect of rate saturation and the effectiveness of ACS to reduce the equivalent time delay and improve tracking performance. In order to further validate the concept of an alternate control scheme, the algorithms were adapted for use with a model-following control system. Pilot-in-the-loop simulations have shown improved performance through the use of ACS during rate saturated conditions. A second flight test will be performed this year in order to further evaluate the use of the alternate control scheme to eliminate the rate limit induced time delay and reduce the danger of PIO.


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    Title :

    Scarlet: DLR Rate Saturation Flight Experiment


    Contributors:

    Publication date :

    1995


    Size :

    6 pages


    Type of media :

    Report


    Type of material :

    No indication


    Language :

    English






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