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failure-tolerance
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Dynamic-programming-based failure-tolerant control for satellite with thrusters in 6-DOF motion
, Article Advances in Space Research ; Volume 65, Issue 12 , 2020 , Pages 2857-2877 ; Assadian, N ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this paper, a dynamic-programming approach to the coupled translational and rotational control of thruster-driven spacecraft is studied. To reduce the complexity of the problem, dynamic-programming-based optimal policies are calculated using decoupled position and attitude dynamics with generalized forces and torques as controls. A quadratic-programming-based control allocation is then used to map the controls to actuator commands. To control the spacecraft in the event of thruster failure, both the dynamic programming policies and control allocation are reconfigured to cope with the losses in controls. The control allocation parameters are adjusted dynamically to ensure the satellite...
Adaptive fin failures tolerant integrated guidance and control based on backstepping sliding mode
, Article Transactions of the Institute of Measurement and Control ; Volume 42, Issue 10 , 2020 , Pages 1823-1833 ; Fathi Jegarkandi, M. F ; Sharif University of Technology
SAGE Publications Ltd
2020
Abstract
An integrated guidance and control (IGC) is designed in this study for a surface-to-air missile considering burned or broken fin as a fault. The IGC model in the pitch plane is developed with various uncertainties in the presence of fin failure. The considered fault may cause a change in the vehicle’s shape that leads to a change in aerodynamic coefficients and consequently in the model. To identify the new model, aerodynamic coefficients are estimated using an estimator and the result is sent to the controller. Then, an adaptive robust controller is designed using the combination of backstepping and sliding mode scheme to compensate fin failure and changes in the dynamic. The simulation...
Fin Failure Tolerant Control of Agile Supersonic Flight Vehicle
, Ph.D. Dissertation Sharif University of Technology ; Fathi Jegarkandi, Mohsen (Supervisor)
Abstract
To make it easier to transition and increase the number of missiles on the launcher, many missiles consider the fins are designed to be foldable. Also, these types of fins can be opened during the flight and therefore reduce the drag force in the initial phase of the flight. One of the disadvantages of this type of design is that the fins may not open during the flight. Moreover, locking the actuator, breaking or destroying some part or all of the control surface of supersonic aircraft due to high speed and temperature and loss of thermal insulation is very probable. This thesis considers the locking, not opening, or even breaking the control surfaces, as well as the destruction of some part...
Resiliency of cortical neural networks against cascaded failures
, Article NeuroReport ; Volume 26, Issue 12 , 2015 , Pages 718-722 ; 09594965 (ISSN) ; Sharif University of Technology
Lippincott Williams and Wilkins
2015
Abstract
Network tools have been extensively applied to study the properties of brain functional and anatomical networks. In this paper, resiliency of Caenorhabditis elegans cortical networks against cascaded failures is studied. To this end, directed network formed by chemical connections and undirected network formed by electrical couplings through gap junctions are considered. Furthermore, two types of C. elegans networks are studied: the whole cortical network of the hermaphrodite type and the network of the posterior cortex in male C. elegans. The results show that resiliency of hermaphrodite and male networks is different. The male cortical network of chemical synapses shows extensively weaker...
Actuator failure-tolerant control of an all-thruster satellite in coupled translational and rotational motion using neural networks
, Article International Journal of Adaptive Control and Signal Processing ; 2018 ; 08906327 (ISSN) ; Assadian, N ; Sharif University of Technology
John Wiley and Sons Ltd
2018
Abstract
The nonlinear model predictive control (MPC) approach is used to control the coupled translational-rotational motion of an all-thruster spacecraft when one of the actuators fails. In order to model the dynamical response of the spacecraft in MPC, instead of direct integration, a neural network (NN) model is utilized. This model is built of a static NN, followed by a dynamic NN. The static NN is used to find the changes of the mapping of “the demanded forces to the thrusters” and “the real torques/forces produced by the remaining thrusters” after the failure occurrence through online training. In this manner, the effect of failed thruster on the dynamics can be found and the need for...