Limiters and Non-Linear Aspects

  • Richard Alden Hyde
Part of the Advances in Industrial Control book series (AIC)


Figure 13.1 shows the relationship between fan speed and throttle servo demand. The severe non-linearity is due to the engine governor cutting in at high fan speeds. Note, that as well as the change in gain there is also a change in the dynamics, they being much faster at high engine speeds. An engine controller has been developed to compensate for this large non-linearity. Refer to the block diagram in appendix B where the engine controller is shown within a dotted box. It gives an approximately linear relationship between the demand APF and achieved fanspeed (which in turn reflects achieved thrust). Note that the compensator relies on knowing the fan speed at which the governor cuts in which in practice will not be known exactly. The engine controller has been left parametric so that the values can be tuned to the actual aircraft if necessary. FORTRAN variables ENJA, ENJB, ENJC, ENJD and ENJE correspond to the values A, B, C, D and E in figure 13.1.


Flight Path Bank Angle Thrust Vector Aerodynamic Lift Pitch Rate 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag London Limited 1995

Authors and Affiliations

  • Richard Alden Hyde
    • 1
  1. 1.Cambridge Control LimitedNewton House, Cambridge Business ParkCambridgeUK

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