Development of the Model-/Sensor-Based Nonlinear Dynamic Inversion Control Technique for Highly Maneuverability Fighter

Kim, Chong-Sup; Yang, Inseok; Koh, Gi-oak; Kim, Byungsoo

doi:10.5302/j.icros.2018.18.0049

Cited by 3 publications

(3 citation statements)

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“…The additional augmentation control with K aug of 0.8 shows quite robust characteristics for the uncertainty of M 0 q , M 0 α , and XCG travel compared to the baseline control law. As can be seen from previous research results, [35][36] INDI control using the measured angular acceleration is quite robust control on the uncertainties of the aerodynamic coefficients. However, the uncertainty of the control effectiveness coefficient for the horizontal tail control surface, M 0 δ es , deteriorates the robustness of the control system because measured angular acceleration cannot reflect control effectiveness uncertainties.…”

Section: Stability and Robustness Analysismentioning

confidence: 62%

“…In most of the fighter aircraft, control gain is designed at the nominal XCG position, and it is applied within the entire XCG travel range because it is difficult to measure XCG information accurately in flight operation. 35 Therefore, flying qualities degrade in case that the XCG travel is wide in flight operation. On the other hand, the additional augmentation control using the measured angular acceleration from the IMU sensor reflects dynamic characteristics changed by the XCG travel, so it is quite robust to the travel of the XCG.…”

Section: Stability and Robustness Analysismentioning

confidence: 99%

See 1 more Smart Citation

Control law design to improve the unexpected pitch motion in slow down turn maneuver

Kim¹,

Jin²,

Koh³

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part G:

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The highly maneuverable fighter aircraft is exposed to unexpected pitch motion such as over-Nz (normal acceleration) and Nz-drop characteristics in transonic and supersonic flight conditions with moderate angle of attack. These characteristics not only degrade flying qualities by destabilizing the aircraft but also threaten flight safety by increasing the structural load. This article proposes an additional augmentation control in the incremental nonlinear dynamic inversion structure, which feeds back the error of pitch angular acceleration to mitigate unexpected pitch motion in slow down turn maneuver. We evaluate the stability, flying qualities, and robustness of the proposed control system by performing the frequency-domain linear analysis and the time-domain numerical simulations based on the mathematical model of advanced trainer aircraft. As a result of the evaluation, the additional augmentation control further improves flying qualities and deceleration performance of the aircraft by decreasing over-Nz and Nz-drop characteristics in high-Nz maneuvering in the transonic flight condition as well as ensuring the stability and robustness of the control system against the major uncertainty factors of the aircraft system compared to the existing transonic pitching moment compensation (TPMC) control in which the predefined scheduling for Nz feedback is used.

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Section: Stability and Robustness Analysismentioning

confidence: 62%

Section: Stability and Robustness Analysismentioning

confidence: 99%

Control law design to improve the unexpected pitch motion in slow down turn maneuver

Kim¹,

Jin²,

Koh³

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part G:

Self Cite

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show abstract

“…In recent years, modern highly maneuverable fighter aircraft have applied more advanced multivariable control techniques to flight control law design to improve flying and handling qualities. The model or sensor-based incremental nonlinear dynamic inversion (INDI) [3] which is based on calculated or measured angular acceleration has been the most popular multivariable control technique. The advantage of the modelbased INDI with classical control techniques is that nonlinearities of aerodynamics directly are incorporated into the control laws without gain scheduling, and separates the flying qualities dependent part and the airframe-dependent part in the control laws [4].…”

Section: Introductionmentioning

confidence: 99%

Stability Margin and Structural Coupling Analysis of a Hybrid INDI Control for the Fighter Aircraft

Kim

Koh

et al. 2021

Int. J. Aeronaut. Space Sci.

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The sensor-based incremental nonlinear dynamic inversion (INDI) using angular acceleration measured by inertial measurement unit (IMU) sensor is a very robust control method on various model uncertainties when the aircraft maneuvers with moderate angle-of-attack (AoA) and high gravity in transonic speed flight conditions. However, the measured angular acceleration has time delay characteristics due to actuator and aircraft dynamics, IMU sensor dynamics, differential angular rate and structural coupling filter (SCF) and so on. These characteristics of angular acceleration feedback reduce dramatically the stability margin of the control system. In this paper, we propose the synchronization filter design method of the control surface feedback path for improving stability margin, based on the proposed hybrid INDI control method using error between the angular acceleration measured from IMU sensor and the angular acceleration calculated from on-board model (OBM) and control surface feedback. To evaluate the proposed control method, we perform the frequency-domain linear analysis and the time-domain simulation. As a result of the evaluation, synchronization method of control surface feedback not only improves the stability margin characteristics of the control system but also eliminates the structural coupling in low frequency range by designing the control surface command feedback using actuator command which is the output of flight control computer (FLCC).

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Development of Flight Control Law for Improvement of Uncommanded Lateral Motion of the Fighter Aircraft

Kim

2020

Int. J. Aeronaut. Space Sci.

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Development of the Model-/Sensor-Based Nonlinear Dynamic Inversion Control Technique for Highly Maneuverability Fighter

Cited by 3 publications

References 0 publications

Control law design to improve the unexpected pitch motion in slow down turn maneuver

Control law design to improve the unexpected pitch motion in slow down turn maneuver

Stability Margin and Structural Coupling Analysis of a Hybrid INDI Control for the Fighter Aircraft

Development of Flight Control Law for Improvement of Uncommanded Lateral Motion of the Fighter Aircraft

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