Effect of actuator nonlinearities on aeroservoelasticity

Taylor, Richard; Pratt, R.W.; Caldwell, B.D.

doi:10.2514/3.21620

Cited by 10 publications

(3 citation statements)

References 4 publications

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“…Firstly, if consideration is given to the amplitude and frequency of both the pilot demand signal and structural feedback signal, the maximum rate demand of the combined input signal to the actuator does not exceed the software rate limit. As a result, the significant phase lags that may be introduced if the rate limit is exceeded are not experienced (Taylor al, 1994(Taylor al, , 1995b. Naturally, if a larger pilot demand signal were considered, then premature rate limiting of the actuator input signal may occur, leading to a violation of the clearance boundary.…”

Section: Performance Boundary For Nonlinear Actuation Systemmentioning

confidence: 99%

“…In addition, some studies involving the use of nonlinear actuation system models have been completed (Maharaj et al, 1991;Stirling and Cowling, 1989). It has been shown (Taylor al, 1994(Taylor al, , 1995b, however, that the presence of a typical aeroservoelastic feedback signal can result in changes to the actuator's frequency response at FCS frequencies as a result of the nonlinear nature of the actuation system. Such a change in actuator performance could have serious consequences in terms of stability of the rigid body dynamics.…”

Section: Introductionmentioning

confidence: 99%

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The application of actuator performance limits to aeroservoelastic compensation

Taylor

Pratt

Caldwell

1999

Transactions of the Institute of Measurement and Control

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An interaction between an aircraft's structural dynamics, unsteady aerodynamics and flight control system can have serious effects on the aircraft both in terms of structural integrity and rigid body stability. The effects of such an interaction, known as aeroservoelasticity, are poorly understood and as a result, very conservative flight control system design methods are used in order to achieve flight clearance. This paper demonstrates how the use of nonlinear actuation system models predicts a maximum boundary for the amplitude of the structural response as a result of the performance limits of the nonlinear actuation system. This envelope of maximum structural response can then be used to allow relaxation of the current design criteria for the structural mode filters. The procedure is demonstrated using a representative aircraft system model. Finally, the results of single input frequency response tests of a representative actuation system are presented in support of the earlier results.

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Section: Performance Boundary For Nonlinear Actuation Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The application of actuator performance limits to aeroservoelastic compensation

Taylor

Pratt

Caldwell

1999

Transactions of the Institute of Measurement and Control

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“…However, SC has been predicted to have a profound effect on fatigue life* 8 ' even subject to these constraints, and this has been borne out by experience of airframe and actuator fatigue life usage during typical SC ground tests. Further concerns are that coupling with flutter modes may occur* 14 ' which could lead to structural damage, and that the propagation of high frequency signals through the FCS could seriously degrade actuator performance for rigid aircraft control* 9 '. Development of analysis tools and procedures to address the SC problem as experienced in aircraft flight control design at Warton, began in the early 1960s with the TSR2 aircraft, and have continued to the present with application to EF2000.…”

Section: Fcs/sc Design Examplesmentioning

confidence: 99%

FCS design for structural coupling stability

Caldwell

1996

Aeronaut. j.

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ACT embodying FBW and digital computing is now implemented routinely in almost all classes of aircraft, and is often essential in achieving performance requirements. However, careful design, thorough understanding, and attention to detail are necessary if the benefits of ACT are to be realised and attention must be focused appropriately among the issues to be resolved to ensure that development proceeds efficiently and overall costs are minimised. This paper introduces structural coupling as one of the important “details” of FCS design, and shows how the “state-of-the-art” has developed at BAe Warton in order to help achieve the performance specification for a modern weapons system, while maintaining a balanced and efficient FCS design effort.

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