Search

This work introduces a new actuator fault estimation approach coupled with a fault‐tolerant control (FTC) strategy for uncertain systems in an output feedback framework. The proposed method involves constructing a Multi‐Layer Neural Network (MLNN) observer‐based fault estimation unit to accurately predict system states and potential faults in the actuator channel. An online control allocation (CA) scheme is then developed, utilizing the derived estimates to actively reconfigure the virtual control signals among the healthy redundant actuators in the event of actuator malfunction. Furthermore, an adaptive neural network‐based output integral sliding mode control scheme is designed based on the virtual control. This integration enhances the overall system's robustness and significantly reduces the chattering effect. The stability analysis of the proposed fault estimations scheme is initially performed using MLNN structure, followed by a comprehensive closed‐loop stability analysis to establish the stability of the entire system. Finally, the effectiveness of the proposed method is validated on a nonlinear six‐degree‐of‐freedom model of multirotor unmanned aerial vehicle aircraft. Numerical simulations under different fault and failure scenarios validate the efficacy of the proposed method. The comparative analysis of the proposed scheme is conducted with the static output feedback control allocations and adaptive allocation strategy. This analysis focuses on evaluating performance using metrics such as root mean square error and mean square deviation, particularly in the presence of faults and failures. The results demonstrate the superior performance of the proposed scheme in fault/failure conditions. [ABSTRACT FROM AUTHOR]

This study considers the numerical design and practical implementation of a new multi-layer neural network observer-based control design technique for unmanned aerial vehicles systems. Initially, an adaptive multi-layer neural network-based Luenberger observer is designed for state estimation by employing a modified back-propagation algorithm. The proposed observer's adaptive nature aids in mitigating the impact of noise, disturbance, and parameter variations, which are usually not considered by conventional observers. Based on the observed states, a nonlinear dynamic inversion-based fast terminal sliding mode controller is designed to attain the desired attitude and position tracking control. This is done by employing a two-loop control structure. Numerical simulations are conducted to demonstrate the effectiveness of the proposed scheme in the presence of disturbance, parameter uncertainty, and noise. The numerical results are compared with current approaches, demonstrating the superiority of the proposed method. In order to assess the practical effectiveness of the proposed method, hardware-in-loop simulations are conducted by utilizing a Pixhawk 6X flight controller that interfaces with the mission planner software. Finally, experiments are conducted on a real F450 quadrotor in a secured laboratory environment, demonstrating stability and good tracking performance of the proposed MLNN observer-based SMC control scheme. [ABSTRACT FROM AUTHOR]

The attitude tracking control problem of flexible spacecraft subjected to parameter uncertainties, time-dependent external disturbances, actuator input nonlinearity, and input actuator misalignment is investigated in this paper. Explicitly, the proposed strategy addresses the input actuator misalignment and dead-zone issues that increase the controller design difficulties. Initially, a new second-order sliding mode observer (SoSMO) using an extended state approach is developed by adding a correction function to improve observer performance to estimate unwanted system perturbations. Then, a distinct SoSMO-based integral-type sliding mode control (ISMC) structure is designed in a unified manner to guarantee the asymptotic stability of the closed-loop system. Comparative numerical simulations under input actuator misalignment, the dead-zone nonlinearity, external disturbance, and inertia uncertainty are performed to illustrate the effectiveness of the proposed controller. [ABSTRACT FROM AUTHOR]

This article introduced fault-tolerant control (FTC) schemes for over-actuated affine non-linear uncertain systems. The proposed methodologies incorporate two different control allocation (CA) units with high-level nonlinear adaptive sliding mode control (NLASMC) strategy. The first FTC strategy is active that utilizes an online CA unit to effectively manage the redundant actuators towards the chosen flight path in faulty conditions. On the other hand, the second FTC scheme is passive based on the idea of a fixed CA scheme and does not require control-input reconfiguration during the faulty condition. A robust NLASMC law is selected to enforce the state trajectories converges to the sliding manifold despite the uncertainty in the model dynamics and external disturbance effect. The proposed schemes are then applied to the nonlinear F16 aircraft detailed model equipped with thrust vectoring (TV) control. The nonlinear simulations on 6-degree-of-freedom (6-DOF) F16 aircraft are performed under the failure of the aileron, rudder, and elevator. It can be visualized that both schemes performed well, but online CA scheme can cope with more faults and failures combinations in comparison to fixed CA schemes. Furthermore, both FTC approaches performed well when compared to existing methods in the literature. [ABSTRACT FROM AUTHOR]

This paper proposes an active fault‐tolerant control (FTC) strategy for a class of non‐linear Lipschitz systems. The proposed FTC approach employs the integral sliding mode control (ISMC) technique due to its inherent capability of dealing with system uncertainties. First, under the nominal fault‐free condition, the linear matrix inequality technique is introduced to design the primary controller for the non‐linear Lipschitz system. To accommodate the actuator faults/failures, the ISMC law is combined with a control allocation scheme that distributes the control signals to the redundant actuators. A non‐linear octorotor system is then used as a test bench to validate the tolerance performance of the proposed FTC strategy. In particular, the proposed FTC strategy is applied for the inner‐loop control, while in the outer loop, a fractional‐order control approach is used to achieve the precise longitude and latitude control. Finally, various simulations are performed to justify the effectiveness of the proposed control scheme. [ABSTRACT FROM AUTHOR]

To research the tendencies of immediate change in the scheduled parameters, a linear parameter–varying control strategy is made in real time for lab-based inverted pendulum system. An adjusted and observing virtual instrument is designed in LabVIEW to construct this mechanism. To obtain the transient response data, a step response is transmitted by virtual instrument to the inverted pendulum by which model of inverted pendulum is identified. System model depicts its characteristics, so this model is employed in designing controller. To improve the performance and robustness, linear parameter–varying controller is created to deal with parameter distinctions. Furthermore, the effectiveness of this designed robust controller is checked by integrating on hardware system. The discovered model is checked by evaluating the presented approaches in real time and simulation outcomes with traditional controller as proportional–integral–derivative controller and linear–quadratic regulator. [ABSTRACT FROM AUTHOR]

The Sikhs were the integral part of Punjab politics especially after Montague-Chelmsford reforms. They although had joint political venture with the Unionist Party of Punjab but later on during the partition drive they missed the train. They were more relying on the Indian National Congress authorities and were betrayed by them. Despite of many offers of Jinnah, they rejected all the offers and joined hands with the Congress. After the Cabinet mission, they mad and re-made all of their policies which led towards of their illusion politics, damaging their cause. Congress leadership assured them many times about their full support to the Sikh leadership and all of their demands. This paper will deal with the political development of partition drive and betrayal of the Sikhs by the Congress that how they were betrayed and the Sikhs were confused in their politics and political tactics and the role of Colonial authorities as well Congressites to get the support of the Sikhs. [ABSTRACT FROM AUTHOR]