Sharif University of Technology
1- PhD. in Aerospace Engineering , University of Kansas , 1989, USA.
2- M.S. in Aerospace Engineering, University of Kansas, 1984, USA.
3- B.S. in Aerospace Engineering, University of Kansas, 1982, USA.
4- B.S. in Civil Engineering, University of Kansas, 1982, USA.
5- FAA Private Pilot License, 1981, USA.
• Aerospace Flight Dynamics and Control,
• Stochastic Optimal Control and Nonlinear Filtering,
• Spacecraft Orbit and Attitude determination and Control,
• Motion Planning and Trajectory Optimization,
• Aeroelastic/Statistical Analysis/Simulation of Dynamic Systems,
• Reliability Based and Multidisciplinary Design Optimization.
Amir H. Khodabakhsh and Seid H. Pourtakdoust Elsevier BV
Marjan Moghanipour, Maryam Kiani, and Seid H. Pourtakdoust Elsevier BV
Seid H Pourtakdoust, Mohamad Fakhari Mehrjardi, Mohammad Hossein Hajkarim, and Forough Nasihati Gourabi SAGE Publications
A review of advanced fault detection and diagnosis (FDD) techniques in attitude control systems (ACSs) of spacecraft is presented. In the first part of the paper, several types of ACS failure scenarios with their practical solutions are presented. Next, the existing approaches to FDD are considered and classified based on different criteria, including applications and design techniques. The literature of this part showed that to enhance ACS operational safety, predictability of failure of an ACS and/or of its components as well as reducing the possibility of failure occurrence is imperative. In addition, fast FDD of various kinds of failures is necessary to guarantee the required reliability of an ACS. The second part of this study highlights challenges involved with different FDD approaches, emphasizing their practical applicability. Current research gaps in FDD techniques such as insensitive residual signal, process monitoring methods, accurate plant model design, easy-to-use software development, FDD tuning process, dealing with noisy sensor measurements, time taken for fault management, the sensitivity of FDD system to faults, and FDD robustness are further elaborated on. Subsequently, the state-of-the-art FDD and its future needs are reflected on. The results of this study could direct spacecraft manufacturers and ACS providers to focus on future needs and improve ground testing for enhanced operational reliability and redundancy.
E. Mohajeri, Seid H Pourtakdoust, and Farshad Pazooki SAGE Publications
Microburst (MB) wind shear is one of the most important meteorological dangers threatening the aircraft (AC) safety and the life of passengers. Though there are some ground-based 3D Lidar systems to detect low-level MB wind shears to alert the pilots, there have been fewer scientific attempts to identify model-based MB parameters via AC onboard air and position data. The latter refers to the development and identification of an acceptable MB model upon which an automatic flight control (AFC) system can be designed to control the AC through wind shear microburst. In essence, accurate knowledge of MB model is an essential prerequisite for design and analysis of AFC systems that can safely fly the AC against microbursts, especially in crucial phases of flight such as takeoff and landing. The present study focuses on online estimation of MB parameters whose results pave the way for effective MB autopilot designs for safe flights through MB. The proposed task is accomplished via a model-based approach using the AC six degrees of freedom (6 DoF) equations of motion (EOM) integrated with the latest verified model of the MB utilizing the extended Kalman filter (EKF). In addition to a sensitivity analysis to determine the key MB model parameters, the performance of the estimation process is enhanced via a hybridization of the genetic algorithm (GA) with the EKF. The results are promising and indicate that the proposed scheme can identify the MB model parameters with sufficient accuracy needed for online applications with AFC design.
Seid H Pourtakdoust, Hadi Zare, and Arian Bighashdel SAGE Publications
A novel integrated aeroelastic model of flapping wings (FWs) undergoing a prescribed rigid body motion is presented. In this respect, the FW nonlinear structural dynamics is enhanced via a newly proposed modification of implicit condensation and expansion (MICE) method that better considers the structural nonlinear effects. In addition, the unsteady aerodynamic model is also an extension of the widely utilized modified strip theory (MST) in which the flexibility effects are accounted for (MST-Flex). The integrated utility of the proposed generalized MICE and MST-Flex is demonstrated to be more realistic for elastic FW flight simulation applications. The prescribed rigid body motion is produced via a servo motor whose dynamics is also considered for the analysis. A special case study is also performed whose combined aeroelastic solution is determined and validated under a sinusoidal flapping motion. To this end, an experimental setup is designed and tested in order to validate the proposed integrated approach for aeroelastic modeling of FWs. There is very good agreement between the numerical and experimental results for elastic FW aerodynamics. It should be noted that the proposed integrated aeroelastic approach is readily adaptable to all kinds of elastic wings with arbitrary geometry and various combination of structural elements.
Seid H Pourtakdoust and Amir H Khodabakhsh SAGE Publications
Most Aeronautical and Astronautical Systems (AAS) are inherently complex, multidisciplinary, nonlinear, and computationally intensive for design and analysis. Utilizing the Reliability-Based Multidisciplinary Design Optimization framework can address the multidisciplinary nature of these systems while accounting for inherent uncertainties. In this paper, an efficient methodology for Reliability-Based Multidisciplinary Design optimization of an aerial vehicle is developed. The computational burden of reliability assessment could make its integration within a Multidisciplinary Design Optimization cycle a formidable task. In this respect, a multilevel Multidisciplinary Design Optimization architecture is proposed in which the computational cost is reduced by considering the reliability analysis, as needed only for critical subsystems. To this end, a single-level Reliability-Based Multidisciplinary Design Optimization is derived using the Performance Measure Analysis and the Karush-Kuhn-Tucker condition. The work demonstrates the integration of this formulation into the proposed multilevel Reliability-Based Multidisciplinary Design Optimization architecture. The proposed design architecture is implemented for an aeroelastic Unpowered Guided Aerial Vehicle whose outcomes are compared with previous results obtained via a mono-level Uncertainty-Based Multidisciplinary Design Optimization architecture.
Seid M. S. Mousavi and Seid H. Pourtakdoust American Institute of Aeronautics and Astronautics (AIAA)
Modeling uncertainties and oscillatory dynamics are control challenges for flapping vehicles. Flapping-wing aerial vehicles are nonlinear time-varying oscillatory systems with flexible multibody dynamics. As such, accurate modeling of these complex systems considering unsteady aerodynamics is a formidable task. Though adaptive controllers can work well with uncertain approximate models, inherent oscillation of flapping systems can degrade their control performance and create undesired control actuations. This paper addresses improvements of neural adaptive dynamic inversion controller toward efficient performance for flapping flight via effective utility of actuator capacity. In this respect, first an assumptive model of a bird-mimetic flapping-wing is considered for simulation and analysis. It is shown that the usage of oscillatory feedback data produces additional error in trajectory tracking and unnecessary oscillatory control actuations. Subsequently, the control loop is modified by adding an adaptive notch filter for real-time estimation, tracking, and removal of dominant oscillatory modes from the feedback data and consequently from the controller output. As a result, the required control effort is effectively reduced and the controller performance is significantly improved. Simulations are provided to demonstrate the efficiency of the proposed scheme in presence of noise, variation of system frequency, disturbances, as well as delay in the control loop.
Seid H. Pourtakdoust and Amir H. Khodabakhsh Elsevier BV
Forough Nasihati Gourabi, Maryam Kiani, and Seid H. Pourtakdoust Elsevier BV
Seid H. Pourtakdoust, M. Fakhari Mehrjardi, and M.H. Hajkarim Elsevier BV
N. Raouf, A. Davar, and Seid H. Pourtakdoust Informa UK Limited
Application of composite lattice structures in aerospace application can bring about considerable weight savings, thus allowing for increased payload weight. This study is devoted to reliability an...
Sasan Amani, Seid H. Pourtakdoust, and Farshad Pazooki Informa UK Limited
Forough Nasihati Gourabi, Maryam Kiani, and Seid H. Pourtakdoust Institute of Electrical and Electronics Engineers (IEEE)
S. Saraygord Afshari, Seid H. Pourtakdoust, B.J. Crawford, R. Seethaler, and A.S. Milani Elsevier BV
Abstract Reliability evaluations play a significant role in engineering applications to ensure the serviceability and safety of advanced structures such as those made of composites. Here, a dynamic reliability evaluation analysis based on the probability density evolution Method (PDEM) has been adapted to assess the reliability of composite structures under uncertainties within the material properties and the external loadings. A Back-Propagation Neural Network approach is employed to identify the system's nonlinear structural response, which is often the case under large deformations. To exemplify, a split Hopkinson pressure bar system was employed to mimic the mechanical behavior of a polypropylene/fiberglass woven composite plate structure under repeated high-strain rate impacts. Subsequently, the reliability prediction was performed offline via the system model and integration of uncertainties, as well as via an online SHM-based approach, and compared to full-scale (direct) experimental reliability values by repeating the impact tests on a population of samples. A material degradation factor has been introduced within the PDEM approach to account for surface damage induced during impacts. Results clearly showed the accuracy of the PDEM in predicting the remaining reliability of the composite after each impact. The method is generic and may be applied to other types of loadings and structures.
Amir Shakouri, Seid H. Pourtakdoust, and Mohammad Sayanjali Elsevier BV
Abstract This paper proposes a solution for multiple-impulse orbital maneuvers near circular orbits for special cases where orbital observations are not globally available and the spacecraft is being observed through a limited window from a ground or a space-based station. The current study is particularly useful for small private launching companies with limited access to global observations around the Earth and/or for orbital maneuvers around other planets for which the orbital observations are limited to the in situ equipment. An appropriate cost function is introduced for the sake of minimizing the total control/impulse effort as well as the orbital uncertainty. It is subsequently proved that for a circle-to-circle maneuver, the optimization problem is quasi-convex with respect to the design variables. For near circular trajectories the same cost function is minimized via a gradient based optimization algorithm in order to provide a sub-optimal solution that is efficient both with respect to energy effort and orbital uncertainty. As a relevant case study, a four-impulse orbital maneuver between circular orbits under Mars gravitation is simulated and analyzed to demonstrate the effectiveness of the proposed algorithm.
Amir Shakouri, Maryam Kiani, and Seid H. Pourtakdoust Institute of Electrical and Electronics Engineers (IEEE)
A novel trajectory design methodology is proposed in the current work to minimize the state uncertainty in the crucial mission of spacecraft rendezvous. The trajectory is shaped under constraints utilizing a multiple-impulse approach. State uncertainty is characterized in terms of covariance, and the impulse time as the only effective parameter in uncertainty propagation is selected to minimize the trace of the covariance matrix. Furthermore, the impulse location is also adopted as the other design parameter to satisfy various translational constraints of the space mission. Efficiency and viability of the proposed idea have been investigated through some scenarios that include constraints on final time, control effort, and maximum thruster limit addition to considering safe corridors. The obtained results show that proper selection of the impulse time and impulse position fulfills a successful feasible rendezvous mission with minimum uncertainty.
Amir Shakouri, Maryam Kiani, and Seid H. Pourtakdoust Elsevier BV
Abstract A new shape-based geometric method (SBGM) is proposed for generation of multi-impulse transfer trajectories between arbitrary coplanar oblique orbits via a heuristic algorithm. The key advantage of the proposed SBGM includes a significant reduction in the number of design variables for an N-impulse orbital maneuver leading to a lower computational effort and energy requirement. The SBGM generates a smooth transfer trajectory by joining a number of confocal elliptic arcs such that the intersections share common tangent directions. It is proven that the well-known classic Hohmann transfer and its bi-elliptic counterpart between circular orbits are special cases of the proposed SBGM. The performance and efficiency of the proposed approach is evaluated via computer simulations whose results are compared with those of optimal Lambert maneuver and traditional methods. The results demonstrate a good compatibility and superiority of the proposed SBGM in terms of required energy effort and computational efficiency.
Forough Nasihati Gourabi, Maryam Kiani, and Seid H. Pourtakdoust Elsevier BV
Abstract Orbit estimation (OE) is a required significant task in almost all space missions. Accordingly, a wide variety of sensors and estimation algorithms have been developed within the last few decades to this aim. However, the current study proposes a novel autonomous OE method that is purely based on temperature data of six orthogonal surfaces of a three-axis stabilized satellite as it orbits around the Earth. While the utility of satellite surface temperature data has been recently investigated for satellite attitude estimation (AE) assuming its navigational information, the present paper is focused on OE via only temperature data that has not been attended to in the related literature. To this end, it is assumed that satellite surfaces are equipped with small plates that are thermally isolated from the internal heat sources so that their temperature changes mainly arise from environmental radiation emanated mainly from the Sun and the Earth. In this sense, a thermal model is developed and demonstrated to show how the satellite surface temperatures and their time rates are the only ingredients needed, as measurement quantities, for the proposed OE method to produce the satellite navigational data in terms of its position and velocity vectors. In addition, the effect of sensor configuration on state observability and estimation accuracy is investigated while the unscented Kalman filter (UKF) is exploited in the estimation process. Performance and viability of the proposed temperature-based OE are verified through Monte Carlo simulations and a comprehensive sensitivity analysis over orbital parameters, satellite initial conditions, sensor accuracy and attitude error.
N. Raouf, Seid H. Pourtakdoust, and S. Samiei Paghaleh Springer Science and Business Media LLC
Structural and system reliability of a typical jet vane (JV) thrust vector control (TVC) subsystem subjected to stochastic loadings is investigated. Jet vane TVC (JVTVC) is used in many aerospace liquid and solid propulsion systems. For the purpose of this work, JVTVC structural reliability of a solid rocket propulsion system is computed using an explicit closed-form limit state function. The JV structure is influenced by the internal ballistic loads emanating out of the solid rocket propulsion internal ballistic, whose performance is modeled via a one-dimensional uniform flow assumption at the engine steady operating condition. Subsequently, JV structural reliability is predicted using the methods of mean value first-order second-moment as well as the first- and second-order reliability methods. The reliability results of the analytical methods are compared with Monte Carlo simulation for verification purposes. Finally, a comprehensive sensitivity analysis is performed to identify the key JVTVC and solid rocket propulsion design parameters affecting the TVC total system reliability. The parameters considered for sensitivity analysis include the JV geometric and structural properties as well as the solid rocket propulsion ballistic and geometric features. It turned out that the vane support arm radius and the vane area are the most important strength and load design variables, respectively, that impact the JVTVC failure reliability.
A. Labibian, S.H. Pourtakdoust, A. Alikhani, and H. Fourati Elsevier BV
This paper is focused on the development and verification of a heat attitude model (HAM) for satellite attitude determination. Within this context, the Sun and the Earth are considered as the main external sources of radiation that could effect the satellite surface temperature changes. Assuming that the satellite orbital position (navigational data) is known, the proposed HAM provides the satellite surface temperature with acceptable accuracy and also relates the net heat flux (NHF) of three orthogonal satellite surfaces to its attitude via the inertial to satellite transformation matrix. The proposed HAM simulation results are verified through comparison with commercial thermal analysis tools. The proposed HAM has been successfully utilized in some researches for attitude estimation, and further studies for practical implementations are still ongoing.
ajad Saraygord Afshari and Seid H. Pourtakdoust Vilnius Gediminas Technical University
Reliability evaluation is a key factor in serviceability and safety analysis of air vehicles. Structural health monitoring methods have grown to a degree of maturity in many industries. However, there is a challenging interest to tie in SHM with reliability assessment. In this respect, consideration of stochastic structural dynamics with SHM data and random loadings opens a new chapter in failure prevention. The current study focuses on the stochastic behavior of structures as a way to relate SHM data with reliability. In this respect, uncertain factors such as atmospheric turbulence, structural parameters, and sensor outputs are considered in the process of reliability assessment. Firstly, an experimental evaluation is conducted using a simple cantilevered beam. Subsequently, system identification is weaved in with a probability density evolution equation for calculating the reliability of a wing structural component. Numerical simulations demonstrate that structural reliability of a typical WSC can be effectively evaluated. The proposed scheme paves the way for new SHM research topics such as online life prediction and reliability based failure prevention.
A Hassanpour and Seid H Pourtakdoust SAGE Publications
Microburst is considered an extreme powerful hazard for aircrafts, especially during takeoff, approach and landing phases of flight. Current airborne piloting practices involve taking alternative routes, if early detection of microburst wind shear (MBW) for its effective avoidance is possible. In this respect, design and analysis of precision automatic flight path control systems for microburst penetration are of outmost importance whose success can significantly reduce crash risks and thus enhance the flight safety. The current study is focused on the design and analysis of a three-dimensional model predictive controller for a wide body transport type aircraft encountering MBW in approach to landing phase of flight. This task is performed utilizing the full nonlinear six degrees of freedom aircraft equations of motion and the most complete 3D model of the MBW and its gradients. The results are promising for online applications as the proposed model predictive controller-based controller has effectively guided and kept the aircraft on the approach glide path with negligible deviations against aircraft initial lateral displacements, sharp edge gust disturbance as well as the MBW.
H. Zare, Seid H. Pourtakdoust, and A. Bighashdel Cambridge University Press (CUP)
ABSTRACTThe effect of inertial forces on the Structural Dynamics (SD) behaviour of Elastic Flapping Wings (EFWs) is investigated. In this regard, an analytical modal-based SD solution of EFW undergoing a prescribed rigid body motion is initially derived. The formulated initial-value problem is solved analytically to study the EFW structural responses, and sensitivity with respect to EFWs’ key parameters. As a case study, a rectangular wing undergoing a prescribed sinusoidal motion is simulated. The analytical solution is derived for the first time and helps towards a conceptual understanding of the overall EFW's SD behaviour and its analysis required in their designs. Specifically, the EFW transient and steady response in on-off servo condition is also attended.
S. Saraygord Afshari and Seid H. Pourtakdoust Wiley
1. Shakouri A., Kiani M., Pourtakdoust Seid H., “A New Shape -Based Multiple-Impulse Strategy for Coplanar Orbital Maneuvers”, Acta Astronautica, Volume 161, pp. 200-208, , Elsevier, 11th, May 2019.
2. Nasihati Gourabi F., Kiani M., Pourtakdoust Seid H., “Autonomous temperature-based orbit estimation”, Aerospace Science and Technology, No. 86, pp. 671-682, , Elsevier, January 2019.
3. Shakouri A., Kiani M., Pourtakdoust Seid H., “Covariance-Based Multiple-Impulse Rendezvous Design”, accepted for publication in IEEE Transactions on Aerospace and Electronic Systems, DOI 10.1109/, IEEE, November 2018.
4. Raouf N., Pourtakdoust Seid H., S. Samiei Paghaleh, “Reliability and Failure analysis of jet vane TVC system”, Journal of Failure Analysis and Prevention, Volume 18, Issue 6,pp. 1635-1642,Springer, October 2018.
5. Labibian A., Pourtakdoust Seid H., A. Alikhani, H. Fourati, “Development of a Radiation Based Heat Model for Satellite Attitude Determination”, Aerospace Science and Technology, No. 82-83, pp. 479-486, , Elsevier, September 27th , 2018.
6. Afshari S. S. , Pourtakdoust Seid H., “Probability Density Evolution For Time-Varying Reliability Assessment Of Wing Structures”, Aviation Journal, ISSN: 1648-7788 /, Volume 22, Issue 2,pp. 52-61, , May 2018.
7. Afshari S. S. , Pourtakdoust Seid H., “Utility of Probability Density Evolution Method for Experimental Reliability Based Active Vibration Control”, Structural Control & Health Monitoring, DOI: 10.1002/, Wiley, April 2018.
8. Bighashdel A., Zare H., Pourtakdoust Seid H., “An Analytical Approach in Dynamic Calibration of Strain Gauge Balances for Aerodynamic Measurements”, IEEE Sensors Journal , DOI 10.1109/, March 2018.
9. Zare H., Bighashdel A., Pourtakdoust Seid H., “Analytical Structural Behavior Of Elastic Flapping Wings Under The Actuator Effect”, The Aeronautical Journal ,Vol. 122, Issue 1254, pp. 1176-1198, Royal Aeronautical Society, U.K , August 2018.
1- Implementation of satellite attitude determination process via nonlinear filtering of thermal data. Patent No. 90141, Intellectual Property Center, Tehran-Iran, October 2016.
2- Development of a 3 DOF Dynamic Force/Moment Measurement System for Flapping Robots. Patent No. 94817, Intellectual Property Center, Tehran-Iran, January 2018.
3- Advanced UAV aerodynamics, flight stability and control: Novel concepts, theory and applications. John Wiley & Sons Inc, December 2016.ISBN-10: 1118928687, ISBN-13: 978-1118928684.
Chapter 17: Constrained Motion Planning and Trajectory Optimization for Unmanned Aerial Vehicles.
Chapter 18: Autonomous Space Navigation Utilizing Nonlinear Filters with MEMS Technology.
4- Recent Advances in Multisensor Attitude Estimation: Fundamental Concepts and Applications.
CRC Press- Taylor and Francis Group, August 2016. ISBN 9781498745710
Chapter 11: Recent Advances in Nonlinear Attitude Estimation Algorithms.