Browsing by Author "Alam, Mushfiqul"

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    Landing gear health assessment: synergising flight data analysis with theoretical prognostics in a hybrid assessment approach
    (PHM Society, 2024-06-27) El Mir, Haroun; King, Stephen; Skote, Martin; Alam, Mushfiqul; Place, Simon
    This study addresses a critical shortfall in aircraft landing gear (LG) maintenance: the challenge of detecting degradation that necessitates intervention between scheduled maintenance intervals, particularly in the absence of hard landings. To address this issue, we introduce a Performance Degradation Metric (PDM) utilising Flight Data Recorder (FDR) output during the touchdown and initial roll phases of landing. This metric correlates time-series accelerometer data from a Saab 340B aircraft’s onboard sensors with non-linear response dynamic models that predict expected LG travel and reaction profiles across a set of ground contact cycles within a single landing. This facilitates the early detection of deviations from standard LG response behaviour, pinpointing potential performance abnormalities. The initiator of this approach is the Landing Sequence Typology, which systematically decomposes each aircraft landing into successive dynamic periods defined by their representative boundary conditions. What follows is the setting of initial parameters for the ordinary differential equations (ODE)s of motion that determine the orientation and impact responses of the most critical components of the LG assembly. Solving these ODEs with the integration of a non-linear representation of an oleo-pneumatic shock absorber model compliant with CS25 aircraft standards produces anticipated profiles of LG travel based on factors such as aircraft weight and speed at touchdown, which are subsequently cross-referenced with real accelerometer data, enhanced by video footage analysis. This footage is crucial for verifying the sequence of LG touchdowns and corresponding accelerometer outputs, thereby bolstering the precision of our analysis. Upon the conclusion of this study, by facilitating the early identification of LG performance deviations in specific landing scenarios, this diagnostic tool shall enable timely maintenance interventions. This proactive approach not only mitigates the risk of damage escalation to other components but also transitions main LG maintenance practices from reactive to proactive.
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    LPV systems analysis using pseudospectra
    (IEEE, 2022-05-27) Alamin, Raheeg; Whidborne, James F.; Alam, Mushfiqul
    Pseudospectra provides a qualitative and quantitative tool for analyzing the stability sensitivity of linear systems. In this paper pseudospectral analysis is extended to Linear Parameter Varying (LPV) systems that are approximated by frozen sets. Two examples of quasi-LPV system models are analyzed, namely an actuated pendulum system and a 2-DOF aeroelastic flutter model. It is shown that use of pseudospectra can overcome some limitations of classical eigenvalue sensitivity as well as providing qualitative information that is straightforward to interpret. Some limitations are discussed and suggestions for further work included.
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    Modelling, simulation and verification of the Saab 340B
    (AIAA, 2023-01-19) Makadia, Jeet; Millidere, Murat; Alam, Mushfiqul; Place, Simon; Whidborne, James F.
    Flight simulation modelling of an aircraft is required for various purposes including performance analysis, flight control design, and flying qualities analysis. The Saab 340B is a twin turboprop transport aircraft designed to seat 30-36 passengers. A Saab 340B has been modified to operate as a flying laboratory for teaching and research purposes at the Cranfield University, United Kingdom. This paper demonstrates a component build-up approach towards creating a simulation model using the data available from the aircraft manufacturer. This approach has previously proven successful in establishing the fundamental working principles of flight dynamics for a Jetstream J31 aircraft. Empirical estimates of the aerodynamic forces and moments acting on the aircraft are calculated from the aircraft’s geometrical parameters using Engineering Sciences Data Unit (ESDU) data sheets. The contribution of this study is a systematic approach to developing an aerodynamic model using ESDU and comparing the results with the collected flight test data across the entire flight envelope for the aircraft.
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    Performance Analysis of eXogenous Kalman Filter for INS/GNSS Navigation Solutions
    (Elsevier, 2023-11-22) Alam, Mushfiqul; Whidborne, James F.; Millidere, Murat
    There are several methods of fusing data for navigation solutions using Inertial Navigation System (INS) aided by Global Navigation Satellite System (GNSS). The most used solutions are nonlinear observer (NLO) and extended Kalman filter (EKF) of various architectures. EKF based estimation methods guarantees sub-optimal solutions but not stability, on the contrary NLO based estimation guarantees stability but not optimality. These complimentary features of EKF and NLO has been combined to design an eXogenous Kalman filter (XKF) where the estimate from the NLO is used as an exogenous signal to calculate the linearized model of the EKF. The performance of the designed XKF is tested on real flight test data collected using a Slingsby T67C ultra-light aircraft. The results show that during the outage of GNSS, in some cases the divergence of position estimates using XKF is lower compared to EKF and NLO, however no clear benefit is achieved.
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    Rapid method for computing reachable landing distances in helicopter autorotative descent
    (AIAA, 2022-05-25) Eberle, Brian F.; Rogers, Jonathan D.; Alam, Mushfiqul; Jump, Michael
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    Real-time motion planning for quadcopter using adaptive spherical expansion and sequential convex optimization
    (AIAA, 2023-01-19) Karaman, Atakan; Kurt, Huseyin Burak; Millidere, Murat; Alam, Mushfiqul
    This paper introduces the Adaptive Spherical Expansion and Sequential Convex Programming (ASE-SCP) as a real-time motion planning algorithm. ASE-SCP algorithm is an improved version of the Spherical Expansion and Sequential Convex Programming (SE-SCP) algorithm in terms of computational speed. ASE-SCP is a hybrid real-time motion planning algorithm which combines the advantages of the Adaptive Spherical Expansion, such as approaching the neighborhood of the global optimal path, and the quick convergence ability of the Sequential Convex Programming. The ASE-SCP algorithm first finds a collision-free path using the adaptive spherical expansion approach. After finding a feasible path from the start point to the target point, the feasible path is re-optimized (tuned) using sequential convex optimization to find the suboptimal path. ASE-SCP Algorithm is applied to a quadcopter model to demonstrate its applicability.
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    SAAB 340B aerodynamic model development using binary particle swarm optimization
    (AIAA, 2024-01-04) Millidere, Murat; Alam, Mushfiqul; Place, Simon; Whidborne, James
    his paper follows-up previous work on the development of a high-fidelity Saab 340B aerodynamic model using system identification methods. In the prior work, Saab 340B flight tests were carried out using different excitations on the control surfaces. The flight test data was collected at predefined trim points. Thrust forces and moment were obtained using the propeller efficiency map provided by the manufacturer. The equation and output error methods were employed to analyse flight test data to estimate aerodynamic parameters in the time domain. This paper follows-up previous work on the development of a high-fidelity Saab 340B aerodynamic model using system identification methods. In the prior work, Saab 340B flight tests were carried out using different excitations on the control surfaces. The flight test data was collected at predefined trim points. Thrust forces and moment were obtained using the propeller efficiency map provided by the manufacturer. The equation and output error methods were employed to analyse flight test data to estimate aerodynamic parameters in the time domain. The paper extends the work to select independent variables in the equation error method in an optimal way using binary particle swarm to determine the best subset of independent variables. The impact of the hyperparameters of the binary PSO approach such as the transfer function scheme, inertia weight updating strategy, and the value of acceleration coefficients is investigated.
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    Simulation framework and development of the Future Systems Simulator
    (Cambridge University Press (CUP), 2024-12-01) Korek, Wojciech T.; Beecroft, P.; Lone, Mudassir; Bragado Aldana, Estela; Mendez, Arthur; Enconniere, J.; Asad, Hafiz ul; Grzedzinski, Kacper; Milidere, Murat; Whidborne, James F.; Li, Wen-Chin; Lu, Linghai; Alam, Mushfiqul; Asmayawati, Saryani; Del Barrio Conde, L.; Hargreaves, D.; Jenkins, D.
    The Aerospace Integration Research Centre (AIRC) at Cranfield University offers industry and academia an open environment to explore the opportunities for efficient integration of aircraft systems. As a part of the centre, Cranfield University, Rolls-Royce, and DCA Design International jointly have developed the Future Systems Simulator (FSS) for the purpose of research and development in areas such as human factors in aviation, single-pilot operations, future cockpit design, aircraft electrification, and alternative control approaches. Utilising the state-of-the-art modularity principles in simulation technology, the FSS is built to simulate a diverse range of current and novel aircraft, enabling researchers and industry partners to conduct experiments rapidly and efficiently. Central to the requirement, a unique, user-experience-centred development and design process is implemented for the development of the FSS. This paper presents the development process of such a flight simulator with an innovative flight deck. Furthermore, the paper demonstrates the FSS’s capabilities through case studies. The cutting-edge versatility and flexibility of the FSS are demonstrated through the diverse example research case studies. In the final section, the authors provide guidance for the development of an engineering flight simulator based on lessons learned in this project.
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    Supporting flight dynamics, parameter identification and simulation teaching with a flying classroom
    (Elsevier, 2024-09-05) Whidborne, James F.; Place, Simon; Alam, Mushfiqul; Lu, Linghai
    Cranfield University recently commissioned a modified Saab 340B airliner as a new flying laboratory classroom. The modifications are briefly described before the use of the flying classroom for flight test teaching is described. A flight dynamic model of the aircraft has been developed, and that, along with the data from the flight test programme are extensively used to support masters-level teaching in flight dynamics, flight simulation and flight parameter identification. Some examples of student results are also briefly presented.
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    Tau theory-based flare control in autonomous helicopter autorotation
    (MDPI, 2023-12-29) Saetti, Umberto; Rogers, Jonathan; Alam, Mushfiqul; Jump, Michael
    A novel trajectory generation and control architecture for fully autonomous autorotative flare that combines rapid path generation with model-based control is proposed. The trajectory generation component uses optical Tau theory to compute flare trajectories for both longitudinal and vertical speed. These flare trajectories are tracked using a nonlinear dynamic inversion (NDI) control law. One convenient feature of NDI is that it inverts the plant model in its feedback linearization loop, which eliminates the need for gain scheduling. However, the plant model used for feedback linearization still needs to be scheduled with the flight condition. This key aspect is leveraged to derive a control law that is scheduled with linearized models of the rotorcraft flight dynamics obtained in steady-state autorotation, while relying on a single set of gains. Computer simulations are used to demonstrate that the NDI control law is able to successfully execute autorotative flare in the UH-60 aircraft. Autonomous flare trajectories are compared to piloted simulation data to assess similarities and discrepancies between piloted and automatic control approaches. Trade studies examine which combinations of downrange distances and altitudes at flare initiation result in successful autorotative landings.