CERES :: Browsing by Author "Whidborne, James F."

Browsing by Author "Whidborne, James F."

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Open Access
A robust adaptive PID-like controller for quadrotor unmanned aerial vehicle systems
(MDPI, 2024-11-27) Boubakir, Ahsene; Souanef, Toufik; Labiod, Salim; Whidborne, James F.
This paper introduces a stable adaptive PID-like control scheme for quadrotor Unmanned Aerial Vehicle (UAV) systems. The PID-like controller is designed to closely estimate an ideal controller to meet specific control objectives, with its gains being dynamically adjusted through a stable adaptation process. The adaptation process aims to reduce the discrepancy between the ideal controller and the PID-like controller in use. This method is considered model-free, as it does not require knowledge of the system’s mathematical model. The stability analysis performed using a Lyapunov method demonstrates that every signal in the closed-loop system is Uniformly Ultimately Bounded (UUB). The effectiveness of the proposed PID-like controller is validated through simulations on a quadrotor for path following, ensuring accurate monitoring of the target positions and yaw angle. Simulation results highlight the performance of this control scheme.
Open Access
The accuracy and computational efficiency of the Loewner framework for the system identification of mechanical systems
(MDPI, 2023-06-20) Dessena, Gabriele; Civera, Marco; Ignatyev, Dmitry; Whidborne, James F.; Zanotti Fragonara, Luca; Chiaia, Bernardino
The Loewner framework has recently been proposed for the system identification of mechanical systems, mitigating the limitations of current frequency domain fitting processes for the extraction of modal parameters. In this work, the Loewner framework computational performance, in terms of the elapsed time till identification, is assessed. This is investigated on a hybrid, numerical and experimental dataset against two well-established system identification methods (least-squares complex exponential, LSCE, and subspace state space system identification, N4SID). Good results are achieved, in terms of better accuracy than LSCE and better computational performance than N4SID.
Open Access
Active Aerodynamic Control of Heavy Goods Vehicles
(Cranfield University, 2013-04) Barden, Jason; Garry, Kevin P.; Whidborne, James F.
Most heavy goods vehicles in service today are fitted with add-on aerodynamic devices. The most common of which is the cab-mounted roof deflector. Such devices provide appreciable drag savings, however, they are often not optimised for the trailer. When a wind yaw angle is present, their savings also diminish as the yaw angle increases. The work conducted within this thesis investigated the possibility of using an adjustable deflector for active flow control. The optimum deflector height for a given trailer height was initially investigated using wind tunnel testing. The variation of this optimum with yaw angle and container separation was then investigated. From the results a 3D look-up table was generated. A control scheme was proposed that used the 3D look-up table requiring only three measurable inputs. The three inputs required were: the wind yaw angle, the container height and the container separation. A pressure differential located on the deflector was found to linearly relate to the wind yaw angle. This relationship allowed on-road measurement of the wind yaw angle and therefore enabled the development of a prototype controller. Extensive on-road testing and unsteady computational simulation were conducted. The results obtained indicated a mean yaw angle magnitude of around 5 perturbed by four fundamental low frequencies. These frequencies were identified in the runs conducted over the test period and an average frequency established. Higher frequency disturbances were attributed to the wakes of leading heavy goods vehicles and were filtered by a suitably chosen numerical filter. Finally, an estimation of the efficiency of the active device was made using a combination of simulation and full scale testing. From the results obtained, an optimised deflector generated an average drag reduction of 7.4%. An estimated additional drag reduction of 1.9% over the optimised deflector was predicted through use of an active system.
Open Access
Active stall flutter suppression for a revised Leishman/Beddoes model
(American Society of Civil Engineers, 2023-12-25) Zheng, Junruoyu; Pontillo, Alessandro; Chen, Lejun; Whidborne, James F.
This paper proposes a nonlinear disturbance observer (NDO) based sliding mode control (SMC) method to the problem of stall flutter suppression for a revised Leishman/Beddoes (L/B) model. To capture accurate aerodynamic characteristics whilst reducing the plant model mismatch, the dynamics of the separation point and the shift of the aerodynamic centre are analysed to improve the structure of the L/B model. Based on this revised L/B model, an active flutter suppression problem which includes aerodynamic disturbances and actuator dynamics is addressed. The inclusion of the actuator dynamics means that the aerodynamic disturbance from the flow separation, induced by the revised L/B model, is considered as an ‘unmatched’ disturbance. To counteract the effect of unmatched disturbances, an NDO-based sliding mode control scheme is applied to suppress stall flutter and to ensure rapid reference tracking performance in both steady and unsteady flow conditions. Simulation results show the improvements of the proposed revised L/B model via a comparative analysis. In addition, the efficacy of the proposed stall flutter suppression scheme is demonstrated
Open Access
Adaptive backstepping nonsingular terminal sliding-mode attitude control of flexible airships with actuator faults
(MDPI, 2022-04-11) Liu, Shiqian; Whidborne, James F.; Song, Sipeng; Lyu, Weizhi
This paper studies the attitude tracking control of a flexible airship subjected to wind disturbances, actuator saturation and control surface faults. Efficient flexible airship models, including elastic deformation, rigid body motions, and their coupling, are established via Lagrange theory. A fast-nonsingular terminal sliding-mode (NTSM) combined with a backstepping control is proposed for the problem. The benefits of this approach are NTSM merits of high robustness, fast transient response, and finite time convergence, as well as the backstepping control in terms of globally asymptotic stability. However, the major limitation of the backstepping NTSM is that its design procedure is dependent on the prior knowledge of the bound values of the disturbance and faults. To overcome this limitation, a wind observer is designed to compensate for the effect of the wind disturbances, an anti-windup compensator is designed to compensate for actuator saturation, and an adaptive fault estimator is designed to estimate the faults of the control surfaces. Globally exponential stability of the closed-loop control system is guaranteed by using the Lyapunov stability theory. Finally, simulation results demonstrate effectiveness and advantages of the proposed control for the Skyship-500 flexible airship, even in the presence of unknown wind disturbances, control surface faults, and different stiffness variants.
Open Access
Adaptive sliding-mode-backstepping trajectory tracking control of underactuated airships
(Elsevier, 2019-12-12) Liu, Shi Qian; Sang, Yuan Jun; Whidborne, James F.
The problem of trajectory tracking control for an underactuated stratospheric airship with model parameter uncertainties and wind disturbances is addressed in the paper. An adaptive backstepping sliding-mode controller is designed from the airship nonlinear dynamics model. The proposed controller has a two-level structure for trajectory guidance, tracking and stability, and the developed controller, based on nonlinear adaptive sliding-mode backstepping method, provides airship attitude and velocity control for the entire flight process. Furthermore, an active set based weighted least square algorithm is applied to find the optimal control surface inputs and the thruster commands under constraints of actuator saturation. The closed-loop system of trajectory tracking control plant is proved to be globally asymptotically stable by using Lyapunov theory. By comparing with traditional backstepping control and PID design, the results obtained demonstrate the capacity of the airship to execute a realistic trajectory tracking mission under two cases of lateral- and roll- underactuations, even in the presence of aerodynamic coefficient uncertainties, and wind disturbances.
Open Access
Adopting exergy analysis for use in aerospace
(Elsevier, 2017-08-05) Hayes, David; Lone, Mudassir; Whidborne, James F.; Camberos, José; Coetzee, Etienne
Thermodynamic analysis methods, based on an exergy metric, have been developed to improve system efficiency of traditional heat driven systems such as ground based power plants and aircraft propulsion systems. However, in more recent years interest in the topic has broadened to include applying these second law methods to the field of aerodynamics and complete aerospace vehicles. Work to date is based on highly simplified structures, but such a method could be shown to have benefit to the highly conservative and risk averse commercial aerospace sector. This review justifies how thermodynamic exergy analysis has the potential to facilitate a breakthrough in the optimization of aerospace vehicles based on a system of energy systems, through studying the exergy-based multidisciplinary design of future flight vehicles.
Open Access
Advanced quadrotor control strategies for health monitoring of overhead power lines.
(Cranfield University, 2021-07) Foudeh, Husam; Luk, Patrick Chi-Kwong; Whidborne, James F.
Research into autonomous control and behavior of mobile vehicles has become increasingly widespread. In particular, unmanned aerial vehicles (UAVs) have seen an upsurge of interest and of the many UAVs available, the multirotor has shown significant potential in monitoring and surveillance tasks. The objective of this research’s programme is to develop novel control that enable quadrotors to track and inspect on high voltage electricity networks. This is a research application that has elicited little attention. This thesis provides a succinct and comprehensive literature research in both state-of-art overhead power lines (OPL) inspection technologies, and quadrotor design and control. It proceeds to motivate, develop and evaluate a learning algorithms controller which exploit the repeated nature of the fault-finding task. Very few iterative learning control (ILC) algorithms have been implemented in this area, and no analysis or practical results exist to specifically investigate UAV performance to modelling uncertainty and exogenous disturbances. In particular, novel contributions are made in ILC algorithms are derived and validated by experimental results on an AscTec Hummingbird quadrotor. It has taken a robust comparisons among several ILC approaches (gradient-based, norm optimal and Newton method ICLs), and the comparisons are largely based on analytical calculated results. In the case of optimal ILC approaches, a new algorithm for nonlinear MIMO systems is developed to cope with exogenous disturbances and noise severely affect UAV as well as a novel tuning method for bnew variation is formulated and applied to the problem of reference tracking for a 6-degree-of-freedom UAV with a two-loop structure. The first loop addresses the system lag and another tackles the possibility of a disturbance commonly encountered when inspection of OPL. The new algorithm contributes to good trajectory tracking and very good convergence speed while minimizing disturbance effects. A linearisation design approach has been extended to enable new updates using quadcopters dynamics. Then constraints have embedded to meet the application demands. After overcoming this deficiency, the ILC controller is further extended based on point-to-point through a straight conductor to fulfil the full task and perform a 2-3 sequence of operations. Finally, the ILC development results are given follow-up using 3D analysis approach where these results are the first ever in this key area.
Open Access
An advanced unmanned aerial vehicle (UAV) approach via learning-based control for overhead power line monitoring: a comprehensive review
(IEEE, 2021-09-03) Foudeh, Husam A.; Luk, Patrick Chi-Kwong; Whidborne, James F.
Detection and prevention of faults in overhead electric lines is critical for the reliability and availability of electricity supply. The disadvantages of conventional methods range from cumbersome installations to costly maintenance and from lack of adaptability to hazards for human operators. Thus, transmission inspections based on unmanned aerial vehicles (UAV) have been attracting the attention of researchers since their inception. This article provides a comprehensive review for the development of UAV technologies in the overhead electric power lines patrol process for monitoring and identifying faults, explores its advantages, and realizes the potential of the aforementioned method and how it can be exploited to avoid obstacles, especially when compared with the state-of-the-art mechanical methods. The review focuses on the development of advanced Learning Control strategies for higher manoeuvrability of the quadrotor. It also explores suitable recharging strategies and motor control for improved mission autonomy.
Open Access
Aerodynamic performance of a flyable flapping wing rotor with dragonfly-like flexible wings
(Elsevier, 2024-03-29) Pan, Yingjun; Guo, Shijun; Whidborne, James F.; Huang, Xun
Drawing inspiration from insect flapping wings, a Flapping Wing Rotor (FWR) has been developed for Micro Aerial Vehicle (MAV) applications. The FWR features unique active flapping and passive rotary kinematics of motion to achieve a high lift coefficient and flight efficiency. This study thoroughly investigates the aerodynamic performance and design of a bio-inspired flexible wing for FWR-MAVs, emphasizing its novel backward-curved wingtip and variable spanwise stiffness resembling a dragonfly's wing. The research departs from previous aerodynamic studies of FWR, which focused predominantly on rectangular and rigid wings, and delves into wing flexibility. Employing Computational Fluid Dynamics (CFD), Computational Structural Dynamics (CSD), and experimental measurements, the study demonstrates the aerodynamic benefits of the dragonfly-inspired FWR wingtip shape and its reinforced structure. Fluid-Structure Interaction (FSI) analysis is used to examine the effects of elastic deformation encompassing twist and bending on aerodynamic forces. The results underscore the importance of bending deformation in enhancing lift and power efficiency and propose a method for analysing variable stiffness along the wingspan using a vortex delay mechanism that is induced by delayed flapping motion. By comparing modelled and measured stiffness, the study validates the flexibility of the FWR wing, revealing optimal aerodynamic efficiency is achieved through moderate flexibility and spanwise stiffness variation. The curving leading-edge beam forming the sweep-back wingtip offers a practical approach to obtaining variable stiffness and aerodynamic benefits for FWR-MAVs. Using the same pair of dragonfly-like flexible wings, FWR-MAVs have effectively exhibited VTOL and hovering flight capabilities, spanning from a 25-g single-motor drive model to a 51-g dual-motor drive model. This research provides valuable insights into flexible wing design for FWR-MAVs, leveraging biomimicry to improve flight efficiency.
Open Access
Analysis of visualization systems in flight simulators
(AIAA, 2023-06-08) Barrio, Luis D.; Korek, Wojciech; Millidere, Murat; Whidborne, James F.
This paper details an analysis of different visualization systems for use in an academic flight simulator, Future Systems Simulator (FSS). First, an overview of off-the-shelf flight simulators is done, detailing the primary features of flight simulators such as Flight Gear, Prepar3D, X-Plane, and Microsoft Flight Simulator (2020). Then, the current setup of the FSS is presented (which uses FlightGear), followed by the process of introducing X-Plane as a scenery-generation tool. To conduct a comparative analysis between FlightGear and X-Plane visual systems, a total of twelve participants with varying levels of experience were invited to participate in the study. The participants performed flight trials in a simple landing scenario at Heathrow Airport. Additionally, the more complex approach at London City Airport was performed with a group of only four highly experienced participants. Participants then gave their feedback and completed a questionnaire. The data from their attempts were recorded for qualitative and quantitative comparison. The results were analyzed to determine which of the two visual systems could be used in the FSS moving forward.
Open Access
Application of an efficient gradient-based optimization strategy for aircraft wing structures
(MDPI, 2018-01-04) Dababneh, Odeh; Kipouros, Timoleon; Whidborne, James F.
In this paper, a practical optimization framework and enhanced strategy within an industrial setting are proposed for solving large-scale structural optimization problems in aerospace. The goal is to eliminate the difficulties associated with optimization problems, which are mostly nonlinear with numerous mixed continuous-discrete design variables. Particular emphasis is placed on generating good initial starting points for the search process and in finding a feasible optimum solution or improving the chances of finding a better optimum solution when traditional techniques and methods have failed. The efficiency and reliability of the proposed strategy were demonstrated through the weight optimization of different metallic and composite laminated wingbox structures. The results show the effectiveness of the proposed procedures in finding an optimized solution for high-dimensional search space cases with a given level of accuracy and reasonable computational resources and user efforts. Conclusions are also inferred with regards to the sensitivity of the optimization results obtained with respect to the choice of different starting values for the design variables, as well as different optimization algorithms in the optimization process.
Open Access
Application of LQG and H∞ gain scheduling techniques to active suppression of flutter
(Elsevier, 2019-11-23) Rosique, Miguel Á.; Alamin, Raheeg; Whidborne, James F.
Aircraft flutter behaviour is highly dependent on flight conditions, such as airspeed, altitude and Mach number. Thus when closed-loop control is applied to suppress flutter, if these variations are taken into account then improved performance can be obtained if the controller has a certain degree of adaptivity to the variations. In this paper, a Linear Parameter-Varying (LPV) model of a rectangular wing including a trailing-edge control surface is considered. Two different gain scheduling controllers based on LQG and H∞ techniques are designed to suppress flutter and reject perturbations. Simulations of the closed-loop system show that gain scheduling techniques are capable of fully stabilizing the system over the full range of the considered air velocity, and they increase flutter speed by more than 90%.
Open Access
Application of Lyapunov matrix inequality based unsymmetrical saturated control to a multi-vectored propeller airship
(SAGE, 2017-04-03) Chen, Li; Whidborne, James F.; Dong, Qi; Duan, Deng Ping
The problem of the design of a controller for a multi-vectored propeller airship is addressed. The controller includes anti-windup that takes into account unsymmetrical actuator constraints. First, a linear transformation is applied to transform the unsymmetrical constraints into symmetric constraints with an amplitude-bounded exogenous disturbance. Then, a stability condition based on a quadratic Lyapunov function for the saturated closed-loop system is proposed. The condition considers both amplitude-bounded and energy-bounded exogenous disturbances. Thus, the controller design problem is transformed into a convex optimization problem expressed in a bilinear matrix inequality form. Two controller design methods were applied: one-step controller and traditional anti-windup controller. The one-step method obtains the controller and the anti-windup compensator in one step while the anti-windup controller method separates this process into the linear controller design and the compensator design. Simulation results showed that both controllers enlarge the stability zone of the saturation system and have good tracking performance. It is shown that the anti-windup controller design method not only has a larger region of stability, but the demanded actuator output exceeds the constraints less and has a smaller anti-windup coefficient matrix compared to the one-step method.
Open Access
Application of Norm Optimal Iterative Learning Control to Quadrotor Unmanned Aerial Vehicle for monitoring overhead power system
(MDPI, 2020-06-22) Foudeh, Husam A.; Luk, Patrick Chi-Kwong; Whidborne, James F.
Wind disturbances and noise severely affect Unmanned Aerial Vehicles (UAV) when monitoring and find in faults in overhead power lines. Accordingly, we propose repetitive learning as a new solution for the problem. In particular, the performance of Iterative Learning Control (ILC)that are based on optimal approaches are examined, namely (i) Gradient-based ILC and (ii) Norm Optimal ILC. When considering the repetitive nature of fault-findin tasks for electrical overhead power lines, this study develops, implements and evaluates optimal ILC algorithms for a UAV model.Moreover, we suggest attempting a learning gain variation on the standard optimal algorithms instead of heuristically selecting from the previous range. The results of both simulations and experiments o gradient-based norm optimal control reveal that the proposed ILC algorithm has not only contributed to good trajectory tracking, but also good convergence speed and the ability to cope with exogenous disturbances such as wind gusts.
Open Access
Applying a modified Smith predictor-bilinear proportional plus integral control for directional drilling
(Elsevier, 2018-01-11) Inyang, Isonguyo J.; Whidborne, James F.
Recently, a Bilinear Proportional plus Integral (BPI) controller was proposed for the control of directional drilling tools commonly used in the oil industry However, there are delays in the measurement signals which reduces the system performance. Here, the BPI controller is extended by addition of a modified Smith predictor. The effectiveness, robustness and stability of the proposed modified Smith Predictor (SP)-BPI controller are analysed. Transient simulations are presented and compared with that of the earlier BPI controller. From the results, it can be surmised that the proposed modified SP-BPI controller significantly reduces the adverse effects of disturbances and time delay on the feedback measurements with respect to stability and performance of the directional drilling tool.
Open Access
Attitude control system for directional drilling bottom hole assemblies
(Iet, 2012-05-31T00:00:00Z) Panchal, Neilkunal; Bayliss, Martin T.; Whidborne, James F.
A general approach for the attitude control of directional drilling tools for the oil and gas industry is proposed. The attitude is represented by a unit vector, thus the non-linearities introduced by Euler angle representations are avoided. Three control laws are proposed, and their stability is proven. Their behaviour is tested by numerical simulation. The merits of the laws from an engineering perspective are highlighted, and some details for the implementation of the laws on directional drilling tools are provided.
Open Access
Autonomous landing of an UAV using H∞ based model predictive control
(MDPI, 2022-12-15) Latif, Zohaib; Shahzad, Amir; Bhatti, Aamer Iqbal; Whidborne, James F.; Samar, Raza
ossibly the most critical phase of an Unmanned Air Vehicle (UAV) flight is landing. To reduce the risk due to pilot error, autonomous landing systems can be used. Environmental disturbances such as wind shear can jeopardize safe landing, therefore a well-adjusted and robust control system is required to maintain the performance requirements during landing. The paper proposes a loop-shaping-based Model Predictive Control (MPC) approach for autonomous UAV landings. Instead of conventional MPC plant model augmentation, the input and output weights are designed in the frequency domain to meet the transient and steady-state performance requirements. Then, the H∞ loop shaping design procedure is used to synthesize the state-feedback controller for the shaped plant. This linear state-feedback control law is then used to solve an inverse optimization problem to design the cost function matrices for MPC. The designed MPC inherits the small-signal characteristics of the H∞ controller when constraints are inactive (i.e., perturbation around equilibrium points that keep the system within saturation limits). The H∞ loop shaping synthesis results in an observer plus state feedback structure. This state estimator initializes the MPC problem at each time step. The control law is successfully evaluated in a non-linear simulation environment under moderate and severe wind downburst. It rejects unmeasured disturbances, has good transient performance, provides an excellent stability margin, and enforces input constraints.
Open Access
Backstepping sliding-mode control of stratospheric airships using disturbance-observer
(Elsevier, 2020-11-16) Liu, Shi Qian; Whidborne, James F.; He, Lei
In the presence of unknown disturbances and model parameter uncertainties, this paper develop a nonlinear backstepping sliding-mode controller (BSMC) for trajectory tracking control of a stratospheric airship using a disturbance-observer (DO). Compared with the conventional sliding mode surface (SMS) constructed by a linear combination of the errors, the new SMS manifold is selected as the last back-step error to improve independence of the adjustment of the controller gains. Furthermore, a nonlinear disturbance-observer is designed to process unknown disturbance inputs and improve the BSMC performances. The closed-loop system of trajectory tracking control plant is proved to be globally asymptotically stable by using Lyapunov theory. By comparing with traditional backstepping control and SMC design, the results obtained demonstrate the capacity of the airship to execute a realistic trajectory tracking mission, even in the presence of unknown disturbances, and aerodynamic coefficient uncertainties
Open Access
A benchtop flight control demonstrator
(SAGE, 2019-07-27) Duran, Joris R.; Whidborne, James F.; Carrizales, Martin
A feedback control demonstrator is described. The demonstrator is intended for the demonstration of control principles applied to flight control of fixed-wing aircraft and hence is suitable for aeronautical programmes. The demonstrator consists of a two degree-of-freedom wing assembly where the wing is free to pitch in an airflow provided by a simple, benchtop wind tunnel. The second degree-of-freedom is provided by a hinged elevator which is actuated by a servomotor. The wing pitch angle is measured with a potentiometer attached to a pivot shaft, thus allowing feedback control of the elevator pitch to be implemented. The aerodynamics of the wing are modelled, the wind tunnel design is described and computational fluid dynamics analysis presented. An embedded controller that implements a proportional–integral–derivative controller and a graphical interface has been developed. Some details of these are also given.