Journal articles: 'Modified feedback linearization'

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Shen, Zhe, and Takeshi Tsuchiya. "Cat-Inspired Gaits for a Tilt-Rotor—From Symmetrical to Asymmetrical." Robotics 11, no. 3 (May 13, 2022): 60. http://dx.doi.org/10.3390/robotics11030060.

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Among the tilt-rotors (quadrotors) developed in recent decades, Ryll’s model with eight inputs (four magnitudes of thrusts and four tilting angles) attracted great attention. Typical feedback linearization maneuvers all of the eight inputs with a united control rule to stabilize this tilt-rotor. Instead of assigning the tilting angles by the control rule, the recent research predetermines the tilting angles and leaves the magnitudes of thrusts with the only control signals. These tilting angles are designed to mimic the cat-trot gait while avoiding the singular decoupling matrix in feedback linearization. To complete the discussions of the cat-gait inspired tilt-rotor gaits, this research addresses the analyses on the rest of the common cat gaits, walk, run, transverse gallop, and rotary gallop. It is found that the singular decoupling matrix exists in walk gait, transverse gallop gait, and rotary gallop gait; the decoupling matrix can hardly be guaranteed to be invertible analytically. Further modifications (scaling) are conducted to these three gaits to accommodate the application of feedback linearization; the acceptable attitudes, leading to invertible decoupling matrix, for each scaled gait are evaluated in the roll-pitch diagram. The modified gaits with different periods are then applied to the tilt-rotor in tracking experiments, in which the references are uniform rectilinear motion and uniform circular motion with or without the equipment of the modified attitude-position decoupler. All the experiments are simulated in Simulink, MATLAB. The result shows that these gaits, after modifications, are feasible in tracking references, especially for the cases equipped with the modified attitude-position decoupler.

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Barzegar, Ali, Farzin Piltan, Mahmood Vosoogh, Abdol Majid Mirshekaran, and Alireza Siahbazi. "Design Serial Intelligent Modified Feedback Linearization like Controller with Application to Spherical Motor." International Journal of Information Technology and Computer Science 6, no. 5 (April 8, 2014): 72–83. http://dx.doi.org/10.5815/ijitcs.2014.05.10.

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Fesharaki, Vahid Jafari, Farid Sheikholeslam, and Mohammad Reza Jahed Motlagh. "Maximum power point tracking with constraint feedback linearization controller and modified incremental conductance algorithm." Transactions of the Institute of Measurement and Control 40, no. 7 (May 3, 2017): 2322–31. http://dx.doi.org/10.1177/0142331217701537.

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In this paper, a robust and constraint feedback linearization controller (FLC) with a modified incremental conductance (Inc.Cond) is proposed for maximum power point tracking (MPPT) in the photovoltaic (PV) systems and overall closed-loop internal stability is guaranteed. The proposed technique is independent with respect to load and is robust against disturbances in the load voltage. A boost chopper converter is utilized as an interface between the PV panel and load to control the system at the best operating point. A modified Inc.Cond method based on current orientation and without division equations is presented. The Inc.Cond method is utilized to generate the desired current for the FLC. The FLC navigates the PV panel to the maximum power point with high speed, whereas the control signal (duty cycle) constraints are monitored. Finally, the MPPT technique is validated through simulation and experimental results and two scenarios are defined to confirm controller robustness and modified Inc.Cond performance.

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Lu, Zhangyu, and Xizheng Zhang. "Composite Non-Linear Control of Hybrid Energy-Storage System in Electric Vehicle." Energies 15, no. 4 (February 21, 2022): 1567. http://dx.doi.org/10.3390/en15041567.

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The underlying circuit control is a key problem of the hybrid energy-storage system (HESS) in electric vehicles (EV). In this paper, a composite non-linear control strategy (CNC) is proposed for the accurate tracking current/voltage of the fully-active HESS by combining the exact feedback linearization method and the sliding mode variable structure control technology. Firstly, by analyzing the circuit characteristics of HESS, the affine non-linear model of fully-active HESS is derived. Then, a rule-based energy management strategy (EMS) is designed to generate the reference current value. Finally, the HESS is linearized by the exact feedback linearization method, and the proposed CNC strategy is developed combined with sliding mode variable structure control technology to ensure fast response, high performance, and robustness. At the same time, the stability proof based on the Lyapunov method is given. Moreover, the performance of the CNC strategy is thoroughly investigated and compared with simulation studies with the traditional PI control and a modified sliding mode control, and its effectiveness under different driving conditions is fully verified.

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Veysi, Mohammad, Mohammad Reza Soltanpour, and Mohammad Hassan Khooban. "A novel self-adaptive modified bat fuzzy sliding mode control of robot manipulator in presence of uncertainties in task space." Robotica 33, no. 10 (May 22, 2014): 2045–64. http://dx.doi.org/10.1017/s0263574714001258.

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SUMMARYIn this paper, an optimal fuzzy sliding mode controller has been designed for controlling the end-effector position in the task space. In the proposed control, feedback linearization method, sliding mode control, first-order fuzzy TSK system and optimization algorithm are utilized. In the proposed controller, a novel heuristic algorithm namely self-adaptive modified bat algorithm (SAMBA) is employed. To achieve an optimal performance, the parameters of the proposed controller as well as the input membership functions are optimized by SAMBA simultaneously. In this method, the bounds of structural and non-structural uncertainties are reduced by using feedback linearization method, and to overcome the remaining uncertainties, sliding mode control is employed. Mathematical proof demonstrates that the closed loop system with the proposed control has global asymptotic stability. The presence of sliding mode control gives rise to the adverse phenomenon of chattering in the end-effector position tracking in the task space. Subsequently, to prevent the occurrence of chattering in control input, a first-order TSK fuzzy approximator is utilized. Finally, to determine the fuzzy sliding mode controller coefficients, the optimization algorithm of Self-Adaptive Modified Bat is employed. To investigate the performance of the proposed control, a two-degree-of-freedom manipulator is used as a case study. The simulation results indicate the favorable performance of the proposed method.

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Wang, Lin Xiang, Rong Liu, and Roderick Melnik. "Feedback Linearization of Hysteretic Thermoelastic Dynamics of Shape Memory Alloy Actuators with Phase Transformations." Advanced Materials Research 47-50 (June 2008): 69–72. http://dx.doi.org/10.4028/www.scientific.net/amr.47-50.69.

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In the current paper, a macroscopic differential model for the hysteretic dynamics in shape memory alloy actuators is constructed by using the modified Landau theory of the first order phase transformation. An intrinsic thermo-mechanical coupling is achieved by constructing the free energy as a function depends on both mechanical deformation and the material temperature. Both shape memory and pseudoelastic effects are modeled. The hysteretic dynamics is linearized by introducing another hysteresis loop via nonlinear feedback strategy, which cancels the original one.

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Kumar, Atal Anil, Jean-François Antoine, and Gabriel Abba. "Control of an Underactuated 4 Cable-Driven Parallel Robot using Modified Input-Output Feedback Linearization." IFAC-PapersOnLine 53, no. 2 (2020): 8777–82. http://dx.doi.org/10.1016/j.ifacol.2020.12.1380.

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Brahmi, Brahim, Ibrahim El Bojairami, Tanvir Ahmed, Asif Al Zubayer Swapnil, Mohammad AssadUzZaman, Inga Wang, Erin McGonigle, and Mohammad Habibur Rahman. "A Novel Modified Super-Twisting Control Augmented Feedback Linearization for Wearable Robotic Systems Using Time Delay Estimation." Micromachines 12, no. 6 (May 21, 2021): 597. http://dx.doi.org/10.3390/mi12060597.

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The research presents a novel controller designed for robotic systems subject to nonlinear uncertain dynamics and external disturbances. The control scheme is based on the modified super-twisting method, input/output feedback linearization, and time delay approach. In addition, to minimize the chattering phenomenon and ensure fast convergence to the selected sliding surface, a new reaching law has been integrated with the control law. The control scheme aims to provide high performance and enhanced accuracy via limiting the effects brought by the presence of uncertain dynamics. Stability analysis of the closed-loop system was conducted using a powerful Lyapunov function, showing finite time convergence of the system’s errors. Lastly, experiments shaping rehabilitation tasks, as performed by healthy subjects, demonstrated the controller’s efficiency given its uncertain nonlinear dynamics and the external disturbances involved.

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ROBBIO, FEDERICO I., DIEGO M. ALONSO, and JORGE L. MOIOLA. "DETECTION OF LIMIT CYCLE BIFURCATIONS USING HARMONIC BALANCE METHODS." International Journal of Bifurcation and Chaos 14, no. 10 (October 2004): 3647–54. http://dx.doi.org/10.1142/s0218127404011491.

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In this paper, bifurcations of limit cycles close to certain singularities of the vector fields are explored using an algorithm based on the harmonic balance method, the theory of nonlinear feedback systems and the monodromy matrix. Period-doubling, pitchfork and Neimark–Sacker bifurcations of cycles are detected close to a Gavrilov–Guckenheimer singularity in two modified Rössler systems. This special singularity has a zero eigenvalue and a pair of pure imaginary eigenvalues in the linearization of the flow around its equilibrium. The presented results suggest that the proposed technique can be promising in analyzing limit cycle bifurcations arising in the unfoldings of other complex singularities.

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Shen, Zhe, Yudong Ma, and Takeshi Tsuchiya. "Feedback linearization-based tracking control of a tilt-rotor with cat-trot gait plan." International Journal of Advanced Robotic Systems 19, no. 4 (July 1, 2022): 172988062211093. http://dx.doi.org/10.1177/17298806221109360.

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With the introduction of the laterally bounded forces, the tilt-rotor gains more flexibility in the controller design. Typical feedback linearization methods utilize all the inputs in controlling this vehicle; the magnitudes as well as the directions of the thrusts are maneuvered simultaneously based on a unified control rule. Although several promising results indicate that these controllers may track the desired complicated trajectories, the tilting angles are required to change relatively fast or in large scale during the flight, which turns to be a challenge in application. The recent gait plan for a tilt-rotor may solve this problem; the tilting angles are fixed or vary in a predetermined pattern without being maneuvered by the control algorithm. Carefully avoiding the singular decoupling matrix, several attitudes can be tracked without changing the tilting angles frequently. While the position was not directly regulated in that research, which left the position-tracking still an open question. In this research, we elucidate the coupling relationship between the position and the attitude. Based on this, we design the position-tracking controller, adopting feedback linearization. A cat-trot gait is further designed for a tilt-rotor to track the reference; three types of references are designed for our tracking experiments: set point, uniform rectilinear motion, and uniform circular motion. The significant improvement with less steady state error is witnessed after equipping with our modified attitude–position decoupler. It is also found that the frequency of the cat-trot gait highly influenced the steady state error.

11

Chew, Chee-Meng, Geok-Soon Hong, and Wei Zhou. "Series damper actuator system based on MR fluid damper." Robotica 24, no. 6 (July 3, 2006): 699–710. http://dx.doi.org/10.1017/s0263574706002876.

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In our recent work, we have proposed a novel force control actuator system called series damper actuator (SDA). We have since built an SDA system based on magneto-rheological fluid (MR) damper. In this paper, the dynamics property of SDA system based on the MR fluid damper (SMRDA) is investigated. The effect of the extra dynamics introduced by the MR fluid damper is revealed by comparing the SMRDA with the SDA system based on a linear Newtonian viscous damper (SNVDA). To linearize the constitutive property of the MR fluid damper, a modified Bingham model is proposed. A force feedback control loop is implemented after the linearization. An experimental SMRDA is built to illustrate the performance of the SDA system.

12

Mishra, Rabi Narayan, and Kanungo Barada Mohanty. "Design and realization of an auto-tuned modified neuro-fuzzy sliding-mode-based IM drive deploying feedback linearization." EPE Journal 28, no. 1 (January 2, 2018): 28–42. http://dx.doi.org/10.1080/09398368.2018.1425242.

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Yao, Xuelian, Yi Yang, and Mingyu Wu. "A Modified Robust Adaptive Fault Compensation Design for Spacecraft with Guaranteed Transient Performance." International Journal of Aerospace Engineering 2023 (March 7, 2023): 1–19. http://dx.doi.org/10.1155/2023/6413085.

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A modified, robust adaptive fault compensation design is proposed for rigid spacecraft systems with uncertain actuator failures and unknown disturbances. The feedback linearization method is first introduced to linearize the nonlinear dynamics, and a model-reference adaptive controller is designed to suppress the unknown external disturbances and stabilize the linearized system. Then, a composite adaptive controller is developed by integrating multiple controllers designed for the corresponding actuator failure conditions, which can handle the essentially multiple uncertainties (failure time, values, type, and failure pattern) of actuator failures simultaneously. To further improve the transient performance problem in the failure compensation control, an H∞ compensator is introduced as an additional item in the basic controller to attenuate the adverse effects on tracking performance caused by parameter estimation errors. From the theoretical analysis and simulation results, it is obvious that the designed scheme can not only guarantee the stability of the closed-loop system is stable and asymptotical tracking properties for a given reference signal but also greatly improve the transient performance of the spacecraft system during the process of failure compensation.

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Fezzani, Amor, Said Drid, Abdesslam Makouf, Larbi Chrifi-Alaoui, and Mohamed Ouriagli. "Speed sensoless robust control of permanent magnet synchronous motor based on second-order sliding-mode observer." Serbian Journal of Electrical Engineering 11, no. 3 (2014): 419–33. http://dx.doi.org/10.2298/sjee1403419f.

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This paper is devoted to the study of the performances of a robust speed sensorless nonlinear control of permanent magnet synchronous machine. In the first part, the controllers are designed using two methods: the first one using the input output feedback linearization control and the second is a nonlinear control based on Lyapunov theory combined with sliding mode control. This second solution shows good robustness with respect to parameter variations, measurement errors and noises. In the second part, the high order sliding mode speed observer is used to overcome the occurring chattering phenomena. The super twisting algorithm is modified in order to design a speed and position observer for PMSM. Finally, simulation results are given to demonstrate the effectiveness and the good performance of the proposed control methods.

15

Sinha, S. C., and Alexandra Dávid. "Control of chaos in nonlinear systems with time-periodic coefficients." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 364, no. 1846 (July 27, 2006): 2417–32. http://dx.doi.org/10.1098/rsta.2006.1832.

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In this study, some techniques for the control of chaotic nonlinear systems with periodic coefficients are presented. First, chaos is eliminated from a given range of the system parameters by driving the system to a desired periodic orbit or to a fixed point using a full-state feedback. One has to deal with the same mathematical problem in the event when an autonomous system exhibiting chaos is desired to be driven to a periodic orbit. This is achieved by employing either a linear or a nonlinear control technique. In the linear method, a linear full-state feedback controller is designed by symbolic computation. The nonlinear technique is based on the idea of feedback linearization. A set of coordinate transformation is introduced, which leads to an equivalent linear system that can be controlled by known methods. Our second idea is to delay the onset of chaos beyond a given parameter range by a purely nonlinear control strategy that employs local bifurcation analysis of time-periodic systems. In this method, nonlinear properties of post-bifurcation dynamics, such as stability or rate of growth of a limit set, are modified by a nonlinear state feedback control. The control strategies are illustrated through examples. All methods are general in the sense that they can be applied to systems with no restrictions on the size of the periodic terms.

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Abdellah, Boucha, Hazzab Abdeldjebar, and Khessam Medjdoub. "An application for nonlinear control by input-output linearization technique for pm synchronous motor drive for electric vehicles." International Journal of Power Electronics and Drive Systems (IJPEDS) 13, no. 4 (December 1, 2022): 1984. http://dx.doi.org/10.11591/ijpeds.v13.i4.pp1984-1992.

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This paper leads to present the modified approach of the speed control for permanent magnet synchronous motors applied to electric vehicles using a nonlinear control. The motor's nonlinear dynamics are transformed into a linearized system model using the input-output feedback linearization technique. There are two permanent magnet synchronous motors (PMSM) in the propulsion model. In order to improve the motor's output torque, the direct component of the current is adjusted to zero. The electronic differential, which is used in the calculations, enables each driving wheel to be controlled individually at each curve. The MATLAB/Simulink software is used to implement modeling and simulation in order to assess the effectiveness of the suggested solution. Simulation studies are used to confirm the efficacy of the proposed technique. The obtained results signify that this approach is more accurate.

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ABJADI, NAVID REZA, and ABBAS KARGAR. "SECOND ORDER SLIDING MODE CONTROL FOR ISLANDED AC MICROGRIDS WITH RENEWABLE POWER RESOURCES." REVUE ROUMAINE DES SCIENCES TECHNIQUES — SÉRIE ÉLECTROTECHNIQUE ET ÉNERGÉTIQUE 69, no. 1 (April 1, 2024): 39–44. http://dx.doi.org/10.59277/rrst-ee.2024.1.7.

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Microgrids have attracted a lot of attention and are the future power systems. This paper proposes a new control scheme for islanded AC microgrid (MG) using master-slave technique. Stability and high performance are vital for islanded MG. Two second order sliding mode controls (SMCs) are designed in stationary reference frame for master and slave units to control the voltage and powers respectively. Both designed controls guarantee the convergence of considered outputs to their reference values. The proposed controls are robust, simple, chattering free and only need local measurements. The control method proposed in this paper can be easily extended to microgrids with any number of slave units and parallel connected inverters. The effectiveness of the proposed control scheme is veriﬁed through simulation results in SIMULINK/MATLAB environment and compared to feedback linearization control and a modified conventional SMC.

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Chen, Jingdong, and Paul I. Ro. "Variable Admittance Control in Sliding Mode for Robust Physical Human–Robot Interaction." Applied Sciences 13, no. 20 (October 12, 2023): 11219. http://dx.doi.org/10.3390/app132011219.

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Intuitive and comfortable physical human–robot interaction (pHRI) can be realized by changing impedance/admittance parameters corresponding to human interaction. However, this dynamic adjustment may result in drastically changed system dynamics, which usually give rise to system instability. We introduce a power envelope regulation strategy designed to constrain the variability of admittance parameters, thereby ensuring system passivity and mitigating the risk of instability. Then, sliding mode control (SMC) is employed to yield stable and robust performance. A new sliding surface is proposed based on feedback linearization, which shows improved tracking performance and stability compared to a conventional sliding surface. The effectiveness of the proposed sliding surface and associated control is theoretically validated. Notably, our modified sliding surface works universally, regardless of the order of the desired admittance equation. The trade-off between system chattering and robustness is effectively managed using a variable–boundary approach, which dynamically adjusts system constraints to optimize performance. In addition, a control algorithm combining acceleration feedback and sliding mode is proposed, showing improved robustness and tracking accuracy performance compared with applying the proposed SMC algorithm exclusively. The efficacy of these methodologies is substantiated through numerical simulations and empirical experiments.

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Psillakis, Haris E., and Antonio T. Alexandridis. "Coordinated Excitation and Static Var Compensator Control with Delayed Feedback Measurements in SGIB Power Systems." Energies 13, no. 9 (May 1, 2020): 2181. http://dx.doi.org/10.3390/en13092181.

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In this paper, we present a nonlinear coordinated excitation and static var compensator (SVC) control for regulating the output voltage and improving the transient stability of a synchronous generator infinite bus (SGIB) power system. In the first stage, advanced nonlinear methods are applied to regulate the SVC susceptance in a manner that can potentially improve the overall transient performance and stability. However, as distant from the generator measurements are needed, time delays are expected in the control loop. This fact substantially complicates the whole design. Therefore, a novel design is proposed that uses backstepping methodologies and feedback linearization techniques suitably modified to take into account the delayed measurement feedback laws in order to implement both the excitation voltage and the SVC compensator input. A detailed and rigorous Lyapunov stability analysis reveals that if the time delays do not exceed some specific limits, then all closed-loop signals remain bounded and the frequency deviations are effectively regulated to approach zero. Applying this control scheme, output voltage changes occur after the large power angle deviations have been eliminated. The scheme is thus completed, in a second stage, by a soft-switching mechanism employed on a classical proportional integral (PI) PI voltage controller acting on the excitation loop when the frequency deviations tend to zero in order to smoothly recover the output voltage level at its nominal value. Detailed simulation studies verify the effectiveness of the proposed design approach.

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Mahmood, Taha S., and Omar F. Lufty. "An Intelligent Feedforward Controller Utilizing a Modified Gorilla Troops Optimization for Nonlinear Systems." Mathematical Modelling of Engineering Problems 9, no. 4 (August 31, 2022): 944–54. http://dx.doi.org/10.18280/mmep.090411.

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This paper presents an intelligent feedforward controller based on the feedback linearization approach to control nonlinear systems. In particular, the nonlinear autoregressive moving average (NARMA-L2) network is trained to reproduce the forward dynamics of the controlled system. Consequently, the trained NARMA-L2 network can be immediately integrated into the inverse feedforward control (IFC) structure. In order to improve the NARMA-L2 structure's ability to approximate nonlinear systems, the NARMA-L2 controller is comprised of two wavelet neural networks (WNNs). In addition, the RASP1 function was used as the mother wavelet function in the structure of the WNN rather than the more common Mexican Hat, Gaussian, and Morlet functions. To prevent the limitations of gradient descent (GD) methods, an artificial gorilla troops optimization (GTO) algorithm is used to determine the optimal settings for the NARMA-L2 inverse controller parameters. In particular, a modified version of the GTO algorithm, which is called the Modified GTO (MGTO) algorithm, is proposed in this work for training the NARMA-L2 inverse controller. This algorithm has demonstrated superior optimization outcomes in comparison to other methods. The effectiveness of the proposed control strategy is demonstrated using two nonlinear dynamical systems. Specifically, several evaluation tests are used to assess the effectiveness of the WNN-based NARMA-L2 in terms of control accuracy and robustness against external disturbances in each of the systems under consideration. These tests clearly demonstrated the effectiveness of the control system. Finally, a comparison study showed that the proposed WNN-based NARMA-L2 controller achieved better control results compared to the multilayer perceptron (MLP) and the radial basis function (RBF)-based NARMA-L2 controllers.

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Lu, Quan, Tieqiang Gang, Guangbo Hao, and Lijie Chen. "Compound optimal control of harmonic drive considering hysteresis characteristic." Mechanical Sciences 10, no. 2 (July 22, 2019): 383–91. http://dx.doi.org/10.5194/ms-10-383-2019.

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Abstract. Hysteresis behavior widely exists in the transmission process of harmonic drives. Eliminating the hysteresis effect is highly desired in the high-precision mechanical transmission, which results in challenges in the control design. This paper aims to improve the tracking accuracy of the motor-harmonic drive serial system. Firstly, a modified Bouc-Wen model based on uniform smooth approximating function is applied to describe the hysteresis behavior of the harmonic drive. By using coordinate transformation and accurate state feedback linearization, we then obtain the mathematical model of the serial system of the motor-harmonic drive. Finally, the reference trajectory is tracked by a compound optimal controller that is based on a linear quadratic regulator. Simulation results show that compared with the disturbance observer-based control (DOBC) using a linear observer, the new compound optimal controller in this paper presents a smoother control signal with the elimination of large amount of high-frequency oscillations. Furthermore, the relative error in the steady state tracking tends to approach to zero and no cyclic fluctuations appears. With the employing of optimal control, the output of the harmonic drive can trace more complex trajectory.

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Pathak, Kaustubh, and Sunil K. Agrawal. "Band-Limited Trajectory Planning and Tracking for Certain Dynamically Stabilized Mobile Systems." Journal of Dynamic Systems, Measurement, and Control 128, no. 1 (November 21, 2005): 104–11. http://dx.doi.org/10.1115/1.2168158.

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In this paper, a general framework for trajectory planning and tracking is formulated for dynamically stabilized mobile systems, e.g., inverted wheeled pendulums and autonomous helicopters. Within this framework, the system state is divided into slow and fast substates. The fast substate is used as a pseudocontrol for tracking a desired slow substate trajectory. First, an exponential fast substate controller is designed to track a fast substate reference trajectory. This fast substate reference trajectory is, in turn, planned so that the slow substate follows its desired trajectory. To ensure that the fast substate reference trajectory is feasible for the exponential controller, it is designed using band-limited “Sinc” functions whose maximum frequency is less than the inverse of the time constant of the exponential controller. To illustrate the procedure, the dynamic model of an inverted wheeled pendulum is reformulated by a partial feedback linearization such that it is amenable to the separation into slow and fast components. The planning and tracking controller design is explained using simulation results. This technique is shown to be easily embedded inside a modified nonlinear model predictive control framework for the slow subsystem. This framework tries to explicitly take the computational delay into account. The computation time required for this technique is encouraging from a real-world implementation perspective.

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LI, Yu, Xiaoxiong LIU, Wei HUANG, Kecheng LI, Ruichen MING, and Weiguo ZHANG. "Design of adaptive flight control law for center of gravity and mass variation and HIL real-time simulation verification." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 40, no. 5 (October 2022): 1030–38. http://dx.doi.org/10.1051/jnwpu/20224051030.

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Considering the influence of the center of gravity (CG) and mass variations on flight dynamics, a nonlinear L1 adaptive control approach is presented in this paper and applied to design a flight controller to achieve the aim of improving the robustness of the flight system against sudden changes in the CG. Based on L1 adaptive control, this approach introduces a feedback linearization strategy to eliminate the known nonlinear dynamics of the aircraft and realize the rapid decoupling of the aircraft states. The nonlinear L1 adaptive control also addresses the problem of insufficient robustness in conventional L1 adaptive control due to overcoming its own known nonlinearities, and then improves the robustness to external disturbances. Additionally, the modified piecewise constant is employed to design the adaptive law to improve the estimation accuracy. Finally, the control performance and robustness of the designed flight control law are verified in the hardware in the loop (HIL) flight control semi-physical experimental platform. Experimental results indicate that the nonlinear L1 adaptive flight control law has strong robustness, which can effectively overcome the disturbance of the CG and mass sudden variations. Moreover, the designed controller takes into account the transient performance while ensuring the steady-state performance of the aircraft with CG change.

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ALONSO, DIEGO M., EDUARDO E. PAOLINI, and JORGE L. MOIOLA. "AN EXPERIMENTAL APPLICATION OF THE ANTICONTROL OF HOPF BIFURCATIONS." International Journal of Bifurcation and Chaos 11, no. 07 (July 2001): 1977–87. http://dx.doi.org/10.1142/s0218127401003152.

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The control of nonlinear systems exhibiting bifurcation phenomena has been the subject of active research in recent years. Contrary to regulation or tracking objectives common in classic control, in some applications it is desirable to achieve an oscillatory behavior. Towards this end, bifurcation control aims at designing a controller to modify the bifurcative dynamical behavior of a complex nonlinear system. Among the available methods, the so-called "anti-control" of Hopf bifurcations is one approach to design limit cycles in a system via feedback control. In this paper, this technique is applied to obtain oscillations of prescribed amplitude in a simple mechanical system: an underactuated pendulum. Two different nonlinear control laws are described and analyzed. Both are designed to modify the coefficients of the linearization matrix of the system via feedback. The first law modifies those coefficients that correspond to the physical parameters, whereas the second one changes some null coefficients of the linearization matrix. The latter results in a simpler controller that requires the measurement of only one state of the system. The dependence of the amplitudes as function of the feedback gains is obtained analytically by means of local approximations, and over a larger range by numerical continuation of the periodic solutions. Theoretical results are contrasted by both computer simulations and experimental results.

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Shekhar, Ravi, and William R. Boos. "Improving Energy-Based Estimates of Monsoon Location in the Presence of Proximal Deserts." Journal of Climate 29, no. 13 (June 14, 2016): 4741–61. http://dx.doi.org/10.1175/jcli-d-15-0747.1.

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Abstract Two theoretical frameworks have been widely used to understand the response of monsoons to local and remote forcings: the vertically integrated atmospheric energy budget and convective quasi-equilibrium (CQE). Existing forms of these frameworks neglect some of the complexities of monsoons, such as the shallow meridional circulations that advect dry air from adjacent deserts into the middle and lower troposphere of monsoon regions. Here the fidelity of energy budget and CQE theories for monsoon location is assessed in a three-dimensional beta-plane model with boundary conditions representative of an off-equatorial continent with a tropical grassland and an adjacent subtropical desert. Energy budget theories show mixed success for various SST and land surface albedo forcings, with the ITCZ being collocated with the energy flux equator but a nonmonotonic relationship existing between ITCZ latitude and cross-equatorial energy transport. Accounting for the off-equatorial position of the unperturbed energy flux equator is shown to be important when a linearization of meridional energy transports is used to quantitatively diagnose ITCZ location. CQE theories that diagnose ITCZ location based on the subcloud moist static energy maximum are shown to have large biases; accounting for convective entrainment of dry air by using a lower-tropospheric mean moist static energy provides a more correct diagnosis of ITCZ location. Finally, it is shown that although ITCZ shifts can be diagnosed by modified CQE and energy budget frameworks, neither can be used in a quantitatively prognostic capacity because of unpredictable feedbacks that are often larger than the imposed forcing.

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Ghaffari, Valiollah, and Ali Vazani. "Observer-based integral controller using composite nonlinear feedback for saturated control systems." Transactions of the Institute of Measurement and Control, January 27, 2023, 014233122211490. http://dx.doi.org/10.1177/01423312221149076.

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Usually, simultaneous improvement of the transient performance and static accuracy is a challenging issue in saturated control systems. Employing an observer and the concept of composite nonlinear feedback, an integral controller is developed for constrained continuous-time systems. To achieve the control goal in the regulation purpose, a linear model is first derived by linearization about the operating point. Some parameters of the integral control are adjusted via the feedback passivation idea. The integral control law would be presented when a passivity condition is satisfied. Adding suitable damping terms to the existing one, the final controller is modified to enhance the response quality of the closed-loop system. The obtained results are evaluated in some numerical real examples. Although such a control method uses linearization, the outcomes of simulations, as well as the calculated performance indexes, discover the efficiency of the designed control system over the comparable ones.

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Salahshoor, Karim, and Amin Sabet Kamalabady. "Adaptive Feedback Linearization Control of SISO Nonlinear Processes Using a Self-Generating Neural Network-Based Approach." Chemical Product and Process Modeling 6, no. 1 (January 3, 2011). http://dx.doi.org/10.2202/1934-2659.1518.

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This paper presents a new adaptive control scheme based on feedback linearization technique for single-input, single-output (SISO) processes with nonlinear time-varying dynamic characteristics. The proposed scheme utilizes a modified growing and pruning radial basis function (MGAP-RBF) neural network (NN) to adaptively identify two self-generating RBF neural networks for online realization of a well-known affine model structure. An extended Kalman filter (EKF) learning algorithm is developed for parameter adaptation of the MGAP-RBF neural networks. The MGAP-RBF growing and pruning criteria have been endeavored to enhance its performance for online dynamic model identification purposes. A stability analysis has been provided to ensure the asymptotic convergence of the proposed adaptive control scheme using Lyapunov criterion. Capabilities of the adaptive feedback linearization control scheme is evaluated on two nonlinear CSTR benchmark processes, demonstrating good performances for both set-point tracking and disturbance rejection objectives.

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Khodaverdian, Maria, and Maryam Malekzadeh. "Attitude stabilization of spacecraft simulator based on modified constrained feedback linearization model predictive control." IET Control Theory & Applications, January 30, 2023. http://dx.doi.org/10.1049/cth2.12429.

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Ashrafifar, Asghar, and Mohsen Fathi Jegarkandi. "Fin failure tolerant control of agile air vehicle using feedback linearization." Measurement and Control, April 22, 2024. http://dx.doi.org/10.1177/00202940241229303.

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The probability of actuator lock, control surface damage, and thermal insulation failure on supersonic aircraft due to high speed and temperature is significant. Additionally, foldable fins are often used in missiles to increase the number of missiles that can be loaded onto a launcher and facilitate transportation, but this design presents the potential for malfunction and failure to open during flight. This study focuses on scenarios where control surfaces do not open or are partially damaged, leading to asymmetries and changes in the vehicle’s dynamics and aerodynamic model. The aim is to detect such failures and design a control system that can withstand these issues. To achieve this, the paper proposes an equivalent aerodynamic model representing the vehicle’s dynamics. The health of each fin is monitored using a nonlinear filter to estimate a parameter. Using separation theory, the dynamic system is divided into fast and slow subsystems, and a control signal for the faulty dynamics is designed based on back-stepping theory principles. Furthermore, the control allocation method is modified to accommodate the condition of the fins and generate the desired control moment. The proposed technique can quickly detect and isolate fin failures within seconds, while the designed controller effectively compensates for these failures.

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Rizal, Yusie, Syamsudin Noor, Sunu Hasta Wibowo, Sarifudin Sarifudin, Ronny Mantala, and Ivan Maududy. "ROBUST SUPER-TWISTING SLIDING MODE CONTROL FOR BALANCING REACTION WHEEL PENDULUM." Engineering and Technology Journal 8, no. 08 (August 9, 2023). http://dx.doi.org/10.47191/etj/v8i8.10.

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Underactuated systems are one of the emerging research topics due to their challenging problems and applications in real-world engineering systems. In this paper, we consider the control problem of balancing the reaction wheel pendulum. Many control methods have been adopted to control the system and one of the common controls is based on sliding mode control (SMC). In SMC, the chattering phenomenon and its solution are widely discussed. Several approaches have been proposed, for example replacing the switching function, second-order SMC, and higher-order SMC. Here, the balancing of the reaction wheel pendulum with disturbances is considered. First, the system model derivation based on the Euler-Lagrange method is discussed. Second, a different approach to designing a controller is given where feedback linearization and robust super-twisting sliding mode control are used. The control performances are compared with those of standard and modified switching functions of first-order sliding mode control. For second-order sliding mode control, the super-twisting and PID super-twisting controllers are employed. In each controller, similar disturbances, namely, impulse signal and sinusoidal signal are used to verify the effectiveness of the controller. We conduct the comparison studies in Matlab/Simulink with fixed controller's gains and the controllers effectively stabilize the pendulum upright and reject the given external disturbances.

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Qiao, Yue, Wang Wei, Yunxiang Li, Shengzui Xu, Lang Wei, Xu Hao, and Re Xia. "CPG-MPC controller for wheel-fin-flipper integrated amphibious robot." Industrial Robot: the international journal of robotics research and application, September 29, 2023. http://dx.doi.org/10.1108/ir-01-2023-0008.

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Purpose The purpose of this paper is to introduce a motion control method for WFF-AmphiRobot, which can effectively realize the flexible motion of the robot on land, underwater and in the transition zone between land and water. Design/methodology/approach Based on the dynamics model, the authors selected the appropriate state variables to construct the state space model of the robot and estimated the feedback state of the robot through the maximum a posteriori probability estimation. The nonlinear predictive model controller of the robot is constructed by local linearization of the model to perform closed-loop control on the overall motion of the robot. For the control problem of the terminal trajectory, using the neural rhythmic movement theory in bionics to construct a robot central pattern generator (CPG) for real-time generation of terminal trajectory. Findings In this paper, the motion state of WFF-AmphiRobot is estimated, and a model-based overall motion controller for the robot and an end-effector controller based on neural rhythm control are constructed. The effectiveness of the controller and motion control algorithm is verified by simulation and physical prototype motion experiments on land and underwater, and the robot can ideally complete the desired behavior. Originality/value The paper designed a controller for WFF-AmphiRobot. First, when constructing the robot state estimator in this paper, the robot dynamics model is introduced as the a priori estimation model, and the error compensation of the a priori model is performed by the method of maximum a posteriori probability estimation, which improves the accuracy of the state estimator. Second, for the underwater oscillation motion characteristics of the flipper, the Hopf oscillator is used as the basis, and the flipper fluctuation equation is modified and improved by the CPG signal is adapted to the flipper oscillation demand. The controller effectively controls the position error and heading angle error within the desired range during the movement of the WFF-AmphiRobot.

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Ruiz, Adrián, Damiano Rotondo, and Bernardo Morcego. "Design of shifting state‐feedback controllers for constrained feedback linearized systems: Application to quadrotor attitude control." International Journal of Robust and Nonlinear Control, December 11, 2023. http://dx.doi.org/10.1002/rnc.7098.

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AbstractThis paper proposes a shifting feedback linearization controller for nonlinear systems under input saturation. The suggested approach for determining a linear parameter‐varying (LPV) state‐feedback controller is based on employing a linear matrix inequality (LMI)‐based methodology, the input‐output feedback linearization approach, and the shifting paradigm concept. The resultant controller deals with a full linearized version of the nonlinear system under state‐dependent input constraints, and it modifies the closed‐loop convergence speed of the system in accordance with changes in the system's region of linearity. The proposed approach is validated by means of an experimental example.

Journal articles on the topic 'Modified feedback linearization'

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