A Direct Adaptive Control Approach in the Presence of Model Mismatch

Joshi, Suresh M.; Tao, Gang; Khong, Thuan

doi:10.2514/6.2009-5620

Cited by 6 publications

(3 citation statements)

References 7 publications

(13 reference statements)

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“…Once actuator failures occur, will be updated. As → 0, → ∞, the associated component in (12) is therefore weighted heavily since becomes large. If the th actuator has damaged completely, the value of will be infinity.…”

Section: Adaptive Fault-tolerant Controlmentioning

confidence: 99%

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Adaptive Fault-Tolerant Control for Flight Systems with Input Saturation and Model Mismatch

Wang

Yang

2013

Discrete Dynamics in Nature and Society

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A novel scheme for fault-tolerant control is proposed in this paper, in which model reference adaptive control method is incorporated with control allocation to cope with simultaneous actuator failures, input saturation, and model mismatch in the flight system. In order to reduce performance degradation caused by actuator failures, the proposed scheme redistributes the control signal to healthy actuators and updates the weighting matrix based on actuator effectiveness. Because of saturation errors resulting from actuator constraints and model mismatch caused by abnormal changes in the system, the original reference model may not be appropriate. Under this circumstance, an adaptive reference model which can also provide satisfactory performance is designed. Simulations of a flight control example are given to illustrate the effectiveness of the proposed scheme.

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Section: Adaptive Fault-tolerant Controlmentioning

confidence: 99%

“…Model mismatch can be caused by icing or damage to the aircraft. Joshi et al first considered this problem in [12] and further developed his work in [13]. Although the previous work has achieved satisfactory tracking performance, none of them considered actuator limits.…”

Section: Introductionmentioning

confidence: 99%

Adaptive Fault-Tolerant Control for Flight Systems with Input Saturation and Model Mismatch

Wang

Yang

2013

Discrete Dynamics in Nature and Society

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“…Such as, overcoming issues associated with gain-scheduled control systems [40], the approximation of inverse dynamics for feedback linearization control of fighter aircraft [41], Unmanned Aerial Vehicle [17], the adaptive control of air-to-air missiles [42], and Neural Adaptive Control for Bank-to-Turn Missiles to adaptively compensate for roll-induced cross coupling [39]. The ability of neural networks in modeling nonlinear systems [39], has been exploited in direct adaptive of a nonlinear controller, as in inverse model control [43].…”

Section: Figure 2-3: Architecture Of the Ifcs F-15 Direct Adaptive "Gmentioning

confidence: 99%

Parameter Estimation Analysis for Hybrid Adaptive Fault Tolerant Control

Eshak¹

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Research efforts have increased in recent years toward the development of intelligent fault tolerant control laws, which are capable of helping the pilot to safely maintain aircraft control at post failure conditions. Researchers at West Virginia University (WVU) have been actively involved in the development of fault tolerant adaptive control laws in all three major categories: direct, indirect, and hybrid. The first implemented design to provide adaptation was a direct adaptive controller, which used artificial neural networks to generate augmentation commands in order to reduce the modeling error. Indirect adaptive laws were implemented in another controller, which utilized online PID to estimate and update the controller parameter. Finally, a new controller design was introduced, which integrated both direct and indirect control laws. This controller is known as hybrid adaptive controller. This last control design outperformed the two earlier designs in terms of less NNs effort and better tracking quality. The performance of online PID has an important role in the quality of the hybrid controller; therefore, the quality of the estimation will be of a great importance. Unfortunately, PID is not perfect and the online estimation process has some inherited issues; the online PID estimates are primarily affected by delays and biases. In order to ensure updating reliable estimates to the controller, the estimator consumes some time to converge. Moreover, the estimator will often converge to a biased value. This thesis conducts a sensitivity analysis for the estimation issues, delay and bias, and their effect on the tracking quality. In addition, the performance of the hybrid controller as compared to direct adaptive controller is explored. In order to serve this purpose, a simulation environment in MATLAB/SIMULINK has been created. The simulation environment is customized to provide the user with the flexibility to add different combinations of biases and delays to the explored derivatives. Biases were considered in the range-500% to 500% and delays in the range 0.5 to 40 seconds. The stability and control derivatives considered in this research effort are a combination of decoupled derivatives in the three channels, longitudinal, lateral, and directional. Numerous simulation scenarios and flight conditions are considered to provide more credibility to the obtained results. In addition, a statistical analysis has been conducted to assess the results. The performance of the control laws has been evaluated in terms of the integral of the error in tracking the three desired angular rates, pitch, roll, and yaw. In addition, the effort of the neural networks exerted to compensate for tracking errors is considered in the analysis as well. The results show that in order to obtain reliable estimates for the investigated derivatives, the estimator needs to generate values with less than five seconds delay. In addition, derivatives estimates are within 50% or-15% off the exact values. Moreover, the importance of updating de...

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