Journal articles: 'Actuators Saturation'

1

Lindner, D. K., T. P. Celano, and E. N. Ide. "Vibration Suppression Using a Proofmass Actuator Operating in Stroke/Force Saturation." Journal of Vibration and Acoustics 113, no. 4 (October 1, 1991): 423–33. http://dx.doi.org/10.1115/1.2930203.

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We consider proofmass actuators for vibration suppression in flexible structures. Proofmass actuators appear to have a significant force-to-weight ratio over other types of actuators; hence, there has been considerable interest in them recently. These actuators, however, have a maximum force capability imposed in part by the stroke length of the proofmass. This nonlinearity is difficult to handle because this constraint cannot be violated (unlike saturation of electronic devices). Furthermore, this constraint is peculiar to this type of actuator. In this paper we consider the control loop structure of a feedback control system which contains a proofmass actuator for vibration suppression. This loop structure is decomposed into inner control loops directly related to the actuator and outer loops which add damping to the structure. The inner loops determine the frequency response of the actuator. Evidently, when the frequency response of the actuator is matched to the stroke/force saturation curve, the actuator is most effective in the vibration suppression loops. Since the stroke/force saturation curve is characterized by the stroke length, mass of the proofmass, and the maximum current delivered by motor electronics, this actuator can be easily sized for a particular application. We also discuss the interaction between the inner loops around the actuator and the structure (with the vibration loops open). To illustrate our results, we consider linear DC motors as proofmass actuators for the COFS-I Mast. To discuss the interaction the actuator and the structure, we develop a simple result based on classical control theory. This result is of independent interest since it leads to a simple procedure for designing low order compensators for single-input-single-output systems with poles near the imaginary axis.

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Zhang, Shaojie, Han Zhang, and Kun Ji. "Incremental Nonlinear Dynamic Inversion Attitude Control for Helicopter with Actuator Delay and Saturation." Aerospace 10, no. 6 (June 1, 2023): 521. http://dx.doi.org/10.3390/aerospace10060521.

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In this paper, an incremental nonlinear dynamic inversion (INDI) control scheme is proposed for the attitude tracking of a helicopter with model uncertainties, and actuator delay and saturation constraints. A finite integral compensation based on model reduction is used to compensate the actuator delay, and the proposed scheme can guarantee the semi-globally uniformly ultimately bounded tracking. The overall attitude controller is separated into a rate, an attitude, and a collective pitch controller. The rate and collective pitch controllers combine the proposed method and INDI to enhance the robustness to actuator delay and model uncertainties. Considering the dynamic of physical actuators, pseudo-control hedging (PCH) is introduced both in the rate and attitude controller to improve tracking performance. By using the proposed controller, the helicopter shows good dynamics under the multiple restrictions of the actuators.

3

Macatangay, Xan, Reza Hoseinnezhad, Anthony Fowler, Sharmila Kayastha, and Alireza Bab-Hadiashar. "Addressing Actuator Saturation during Fault Compensation in Model-Based Underwater Vehicle Control." Electronics 12, no. 21 (November 1, 2023): 4495. http://dx.doi.org/10.3390/electronics12214495.

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Robust control systems are a necessity for autonomous underwater vehicle (AUV) systems due to the challenges they face during operation. Many AUV control-design methods have been developed for different actuator configurations, with robustness against model parameter uncertainties, environmental disturbances, and system faults. Actuator faults can reduce the physical capabilities of a system, which can be compensated for through control re-allocation. However, the increased control allocation to the remaining actuators may cause actuator saturation and reduce controller performance. In this work, we present a depth-pitch model-based nonlinear control law that directly considers actuator saturation, and a fault-tolerant control allocation method for a hybrid AUV actuator configuration. Two types of actuator faults are considered for an underwater vehicle with a hybrid actuator configuration. The proposed controller is implemented in a simulated system, and its trajectory tracking performance is compared with a baseline system without fault or saturation tolerance. To determine the utility of the proposed saturation and fault tolerance control methods, the tracking performance in these simulations is quantified in terms of the settling time, post-fault peak values, and root mean square of the depth and pitch errors.

4

Wang, Man, Jianying Yang, and Nan Li. "Adaptive Fault-Tolerant Control for Flight Systems with Input Saturation and Model Mismatch." Discrete Dynamics in Nature and Society 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/712486.

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A novel scheme for fault-tolerant control is proposed in this paper, in which model reference adaptive control method is incorporated with control allocation to cope with simultaneous actuator failures, input saturation, and model mismatch in the flight system. In order to reduce performance degradation caused by actuator failures, the proposed scheme redistributes the control signal to healthy actuators and updates the weighting matrix based on actuator effectiveness. Because of saturation errors resulting from actuator constraints and model mismatch caused by abnormal changes in the system, the original reference model may not be appropriate. Under this circumstance, an adaptive reference model which can also provide satisfactory performance is designed. Simulations of a flight control example are given to illustrate the effectiveness of the proposed scheme.

5

Guo, Jishu, Junmei Guo, and Zhongjun Xiao. "Robust tracking control for two classes of variable stiffness actuators based on linear extended state observer with estimation error compensation." International Journal of Advanced Robotic Systems 17, no. 2 (March 1, 2020): 172988142091177. http://dx.doi.org/10.1177/1729881420911774.

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In this article, a novel robust tracking control scheme based on linear extended state observer with estimation error compensation is proposed for the tracking control of the antagonistic variable stiffness actuator based on equivalent nonlinear torsion spring and the serial variable stiffness actuator based on lever mechanism. For the dynamic models of these two classes of variable stiffness actuators, considering the parametric uncertainties, the unknown friction torques acting on the driving units, the unknown external disturbances acting on the output links and the input saturation constraints, an integral chain pseudo-linear system with input saturation constraints and matched lumped disturbances is established by coordinate transformation. Subsequently, the matched lumped disturbances in the pseudo-linear system are extended to the new system states, and we obtain an extended integral chain pseudo-linear system. Then, we design the linear extended state observer to estimate the unknown states of the extended pseudo-linear system. Considering the input saturation constraints in the extended pseudo-linear system and the estimation errors of the linear extended state observer with fixed preset observation gains, the adaptive input saturation compensation laws and the novel estimation error compensators are designed. Finally, a robust tracking controller based on linear extended state observer, sliding mode control, adaptive input saturation compensation laws, and estimating error compensators is designed to achieve simultaneous position and stiffness tracking control of these two classes of variable stiffness actuators. Under the action of the designed controller, the semi-global uniformly ultimately bounded stability of the closed-loop system is proved by the stability analysis of the candidate Lyapunov function. The simulation results show the effectiveness, robustness, and adaptability of the designed controller in the tracking control of these two classes of variable stiffness actuators. Furthermore, the simulation comparisons show the effectiveness of the proposed estimation error compensation measures in reducing the tracking errors and improving the disturbance rejection performance of the controller.

6

Ijaz, Salman, Mirza T. Hamayun, Lin Yan, and Cun Shi. "Active fault-tolerant control for vertical tail damaged aircraft with dissimilar redundant actuation system using integral sliding mode control." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 7 (September 15, 2018): 2361–78. http://dx.doi.org/10.1177/0954406218790280.

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The research about the dissimilar redundant actuation system has indicated the potential fault-tolerant capability in modern aircraft. This paper proposed a new design methodology to achieve fault-tolerant control of an aircraft equipped with dissimilar actuators and is suffered from vertical tail damage. The proposed design is based on the concept of online control allocation to redistribute the control signals among healthy actuators and integral sliding mode controller is designed to achieve the closed-loop stability in the presence of both component and actuator faults. To cope with severe damage condition, the aircraft is equipped with dissimilar actuators (hydraulic and electrohydraulic actuators). In this paper, the performance degradation due to slower dynamics of electrohydraulic actuator is taken in account. Therefore, the feed-forward compensator is designed for electrohydraulic actuator based on fractional-order control strategy. In case of failure of hydraulic actuator subject to severe damage of vertical tail, an active switching mechanism is developed based on the information of fault estimation unit. Additionally, a severe type of actuator failure so-called actuator saturation or actuator lock in place is also taken into account in this work. The proposed strategy is compared with the existing control strategies in the literature. Simulation results indicate the dominant performance of the proposed scheme. Moreover, the proposed controller is found robust with a certain level of mismatch between the actuator effectiveness level and its estimate.

7

Shojaei, Khoshnam. "Saturated output feedback control of uncertain nonholonomic wheeled mobile robots." Robotica 33, no. 1 (January 31, 2014): 87–105. http://dx.doi.org/10.1017/s0263574714000046.

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SUMMARYMany research works on the control of nonholonomic wheeled mobile robots (WMRs) do not consider the actuator saturation problem and the absence of velocity sensors in practice. The actuator saturation deteriorates the tracking performance of the controller, and the use of velocity sensors increases the cost and weight of WMR systems. This paper simultaneously addresses these problems by designing a saturated output feedback controller for uncertain nonholonomic WMRs. First, a second-order input–output model of nonholonomic WMRs is developed by defining a suitable set of output equations. Then a saturated adaptive robust tracking controller is proposed without velocity measurements. For this purpose, a nonlinear saturated observer is used to estimate robot velocities. The risk of actuator saturation is effectively reduced by utilizing saturation functions in the design of the observer–controller scheme. Semi-global uniform ultimate boundedness of error signals is guarantied by the Lyapunov stability analyses. Finally, simulation results are provided to show the effectiveness of the proposed controller. Compared with one recent work of the author, a comparative study is also presented to illustrate that the proposed saturated controller is more effective when WMR actuators are subjected to saturation.

8

Tsiakmakis, Kyriakos, Vasileios Delimaras, Argyrios T. Hatzopoulos, and Maria S. Papadopoulou. "Displacement Measurement System and Control of Ionic Polymer Metal Composite Actuator." WSEAS TRANSACTIONS ON SYSTEMS AND CONTROL 18 (June 12, 2023): 144–53. http://dx.doi.org/10.37394/23203.2023.18.15.

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This work presents a study comparing two control methods used in IPMC actuators. The position of the free end of the actuator is extracted using low-frequency signals, and the driving voltage is limited to ±3 V. This paper also proposes a new image sensor-based method for measuring displacement, which uses the actuator's route and applied current to predict the direction and detect the free edge using small areas of interest. The algorithm detects the area of the moving route, reduces the searching area of the IPMC's free edge, and predicts the edge direction. An experimental setup was established using a laser sensor and camera system. The results of simple computer usage reveal that the new technique is 17% faster. The paper also discusses model identification using a black-box approach. A major objective is to find the optimal control settings for various methods to highlight the issue of saturation and define the duration in which the IPMC actuator can be controlled.

9

Yaqubi, Sadeq, Morteza Dardel, and Hamidreza Mohammadi Daniali. "Nonlinear dynamics and control of crank–slider mechanism with link flexibility and joint clearance." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 5 (June 29, 2015): 737–55. http://dx.doi.org/10.1177/0954406215593773.

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Dynamical behaviors and control of planar crank–slider mechanism considering the effects of joint clearance and link flexibility are studied. A control scheme for maintaining continuous contact is proposed. It was observed that using one actuator for control scheme might cause the actuator to reach its saturation limit, a problem that was bypassed by installing an additional actuator on connecting rod. In one actuator case, only continuous contact can be obtained, while with the aid of two actuators, point contact can be achieved. Great improvements in the performance of mechanism and reduction of vibrations are observed in the case of using an additional actuator.

10

Wang, Guoliang, and Bo Feng. "Finite-Time Stabilization for Discrete-Time Delayed Markovian Jump Systems with Partially Delayed Actuator Saturation." Discrete Dynamics in Nature and Society 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/1304379.

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The finite-time control problem of discrete-time delayed Markovian jump systems with partially delayed actuator saturation is considered by a mode-dependent parameter approach. Different from the traditionally saturated actuators, a kind of saturated actuator being partially delay-dependent is firstly proposed, where both nondelay and delay states are included and occur asynchronously. Moreover, the probability distributions of such two terms are described by the Bernoulli variable and are taken into account in the controller design. Sufficient conditions for the existence of the desired controller are presented with LMIs. Finally, a numerical example is provided to show the effectiveness and superiority of the obtained results.

11

Bencsik, László, and László L. Kovács. "Reduction of the effect of actuator saturation with periodic servo-constraints." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, no. 1 (October 20, 2016): 96–105. http://dx.doi.org/10.1177/0954406216674980.

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Saturation is an undesired event in trajectory tracking control of mechanical systems. When the actuators of a robotic device saturate, the solution of the inverse dynamics problem cannot fully be realized, which results in deviations from the desired trajectory and loss of performance. It is generally hard to consider the limited actuator torques and the corresponding nonlinear effects in the control design. The most common way to handle the problem is recalculating the control forces and trying to adjust the desired trajectory such that saturation will not happen. In contrast we propose a switched control approach, where, upon saturation, different sets of inputs are varied periodically to keep the reference point of the robot on the desired trajectory. For this, the desired motion is formulated by means of servo-constraints, and the periodic switching of these constraints is adjusted according to the variation of a new, manipulability type performance measure. It is demonstrated that the proposed controller can effectively reduce the trajectory following error due to actuator saturation. A typical robotic benchmark example is provided to show the application of the method, and to compare it with other approaches taken from the literature.

12

Lin, Jinxing. "Exponential Estimates and Stabilization of Discrete-Time Singular Time-Delay Systems Subject to Actuator Saturation." Discrete Dynamics in Nature and Society 2012 (2012): 1–27. http://dx.doi.org/10.1155/2012/414373.

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This paper is concerned with exponential estimates and stabilization of a class of discrete-time singular systems with time-varying state delays and saturating actuators. By constructing a decay-rate-dependent Lyapunov-Krasovskii function and utilizing the slow-fast decomposition technique, an exponential admissibility condition, which not only guarantees the regularity, causality, and exponential stability of the unforced system but also gives the corresponding estimates of decay rate and decay coefficient, is derived in terms of linear matrix inequalities (LMIs). Under the proposed condition, the exponential stabilization problem of discrete-time singular time-delay systems subject actuator saturation is solved by designing a stabilizing state feedback controller and determining an associated set of safe initial conditions, for which the local exponential stability of the saturated closed-loop system is guaranteed. Two numerical examples are provided to illustrate the effectiveness of the proposed results.

13

Xia, Shuyan, Daolin Xu, Haicheng Zhang, and Yousheng Wu. "Response control of a floating airport in heading waves with output saturation." Journal of Vibration and Control 25, no. 3 (August 23, 2018): 571–80. http://dx.doi.org/10.1177/1077546318790592.

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This paper presents a nonlinear control strategy to stabilize the response of a floating platform in waves. The floating platform consists of multiple floating modules connected in sequence with flexible connectors. A nonlinear dynamic model with a number of controllers is developed for the stability control of the chain-shape floating structure. The backstepping method in conjunction with the Lyapunov stability criteria is proposed to derive the control law for each of the control actuators where the actuator forces are limited with output saturation. The numerical experiments illustrate the feasibility and effectiveness of the control strategy in various conditions of heading waves. The performance of the control method is discussed, especially associated with the saturated output.

14

Prado, Alvaro Javier, Marco Herrera, Xavier Dominguez, Jose Torres, and Oscar Camacho. "Integral Windup Resetting Enhancement for Sliding Mode Control of Chemical Processes with Longtime Delay." Electronics 11, no. 24 (December 18, 2022): 4220. http://dx.doi.org/10.3390/electronics11244220.

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The effects of the windup phenomenon impact the performance of integral controllers commonly found in industrial processes. In particular, windup issues are critical for controlling variable and longtime delayed systems, as they may not be timely corrected by the tracking error accumulation and saturation of the actuators. This work introduces two anti-windup control algorithms for a sliding mode control (SMC) framework to promptly reset the integral control action in the discontinuous mode without inhibiting the robustness of the overall control system against disturbances. The proposed algorithms are intended to anticipate and steer the tracking error toward the origin region of the sliding surface based on an anti-saturation logistic function and a robust compensation action fed by system output variations. Experimental results show the effectiveness of the proposed algorithms when they are applied to two chemical processes, i.e., (i) a Variable Height Mixing Tank (VHMT) and (ii) Continuous Stirred Tank Reactor (CSTR) with a variable longtime delay. The control performance of the proposed anti-windup approaches has been assessed under different reference and disturbance changes, exhibiting that the tracking control performance in the presence of disturbances is enhanced up to 24.35% in terms of the Integral Square Error (ISE) and up to 88.7% regarding the Integral Time Square Error (ITSE). Finally, the results of the proposed methodology demonstrated that the excess of cumulative energy by the actuator saturation could reduce the process resources and also extend the actuator’s lifetime span.

15

Fu, Tianlei, Lianwu Guan, Yanbin Gao, and Chao Qin. "An Anti-Windup Method Based on an LADRC for Miniaturized Inertial Stabilized Platforms on Unmanned Vehicles in Marine Applications." Journal of Marine Science and Engineering 12, no. 4 (April 2, 2024): 616. http://dx.doi.org/10.3390/jmse12040616.

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This paper investigates an anticipatory activation anti-windup approach based on Linear Active Disturbance Rejection Control (LADRC) to address the influences of accelerated saturation on the actuators in a Miniaturized Inertial Stabilized Platform (MISP) with extreme external disturbance. The proposed method aims to eliminate the high-frequency vibrations on the Line of Sight (LOS) of electro-optical devices during actuator saturation. To achieve this, the Linear Extended State Observer (LESO) is modified by adding saturation feedback to the total disturbance observed state variable, which is operated as an anticipatory activation anti-windup compensator. The stability of the proposed controller is discussed, and the gains are optimized by the Linear Matrix Inequality (LMI) constraints though quadratic programming and an H-infinite performance indicator. Additionally, as the multiple activated scheme for anti-windup, the effectiveness of immediate activation in dealing with accelerated saturation is compared and analyzed. These comparisons and verification are implemented through simulations, where the external disturbance is introduced using recorded attitude data from USV sailing. Finally, experiments are conducted on an MISP for a visual tracking system, demonstrating that the anticipatory activation mothed effectively suppresses high-frequency vibrations on the LOS during instances of accelerated saturation.

16

Kirecci, A., and M. J. Gilmartin. "Application of learning to high-speed robotic manipulators." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 212, no. 4 (June 1, 1998): 315–23. http://dx.doi.org/10.1243/0959651981539497.

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When a desired signal is applied to a servo system it responds in a characteristic fashion and follows the required trajectory with an error. The physical features of the actuators and the gain setting of the controller are the main parameters that determine the response of the system. Controllers with fixed gain values are effective for many conventional processes using slow-speed manipulators. However, there are several cases where the precise tracing of a fast trajectory under different payloads requires more advanced control techniques. When the motion is cyclical, learning control is one advanced technique which is appropriate to use. Depending solely on measurements of data from the preceding cycle, its implementation in real time is both fast and efficient. In practice, however, it has been observed that learning can induce high-frequency ripples on the tuned command curve which with increasing iterations result eventually in the saturation of the system's actuators. In this study, the use of on-line learning control techniques is discussed and a new approach using digital filters is implemented to prevent actuator saturation from occurring when learning is applied. A planar robotic manipulator has been designed and built to investigate the practical problems of learning control, particularly when the system runs at high speeds.

17

Rasouli, Padideh, Mazda Moattari, and Ahmad Forouzantabar. "Nonlinear disturbance observer-based fault-tolerant control for flexible teleoperation systems with actuator constraints and varying time delay." Transactions of the Institute of Measurement and Control 43, no. 10 (March 23, 2021): 2246–57. http://dx.doi.org/10.1177/0142331221993246.

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In this paper, designing a control law for teleoperation systems with flexible-link slave robots in the presence of dynamic uncertainties, disturbances, actuator faults and actuator constraints with time-varying communication delays is addressed. This study proposes a simple anti-saturation nonlinear fault-tolerant controller incorporating a disturbance observer. The attractive features of the proposed controller include the ability to cope with disturbances, avoiding actuators exceeding their usual bounds, and compensating for the actuator faults. Besides which, the controller has a simple structure, does not need a fault detection mechanism, and coordinates the master’s motion speed with the slave’s actuator. A Lyapunov–Krasovskii functional is used to prove the stability and tracking performance of the teleoperation system. The feasibility and efficiency of the proposed controller are corroborated through simulation results.

18

Tyan, Feng, and Dennis S. Bernstein. "Anti-windup compensator synthesis for systems with saturation actuators." International Journal of Robust and Nonlinear Control 5, no. 5 (1995): 521–37. http://dx.doi.org/10.1002/rnc.4590050510.

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19

Si, Zhi-Yuan, Xian-Xu ‘Frank’ Bai, and Li-Jun Qian. "Asymmetric Hysteresis Modeling Approach Featuring “Inertial System + Shape Function” for Magnetostrictive Actuators." Materials 13, no. 11 (June 5, 2020): 2585. http://dx.doi.org/10.3390/ma13112585.

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Hysteresis of the actuators based on magnetostrictive materials influences the control performance of the application systems. It is of importance and significance to establish an effective hysteresis model for the magnetostrictive actuators for precision engineering. In this paper, based on the analysis of the Duhem model, a first-order inertial system with hysteresis characteristic under harmonic input is used to describe the hysteresis caused by the inertia of the magnetic domains of magnetostrictive materials. Shape function is employed to describe the pinning of domain walls, the interactions of different magnetic domains of magnetostrictive materials, and the saturation properties of the hysteresis. Specifically, under an architecture of “inertial system + shape function” (ISSF-Duhem model), firstly a new hysteresis model is proposed for magnetostrictive actuators. The formulation of the inertial system is constructed based on its general expression, which is capable of describing the hysteresis characteristics of magnetostrictive actuators. Then, the developed models with a Grompertz function-based shape function, a modified hyperbolic tangent function-based shape function employing an exponential function as an offset function, a one-sided dead-zone operator-based shape function are compared with each other, and further compared with the classic modified Prandtl–Ishlinskii model with a one-sided dead-zone operator. Sequentially, feasibility and capability of the proposed hysteresis model are verified and evaluated by describing and predicting the hysteresis characteristics of a commercial magnetostrictive actuator.

20

Leu, Ming C., Sangsik Yang, and Andrew U. Meyer. "Anti-Windup Control of Second-Order Plants With Saturation Nonlinearity." Journal of Dynamic Systems, Measurement, and Control 115, no. 4 (December 1, 1993): 715–20. http://dx.doi.org/10.1115/1.2899202.

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All real-world control systems have saturation nonlinearity in final control elements (including actuators). When controllers involve integral action, reset windup can cause instability as well as make system performance unsatisfactory. Based on the describing function method and the generalized Popov criterion, this paper presents analysis of the global stability of a control system having a saturating second-order plant, both with and without using a deadbeat limiting scheme to constrain its controller output. The improvement of system performance by incorporating the anti-windup feature in the controller is illustrated by computer simulations.

21

An, H., H. Xia, and C. Wang. "Finite-time output tracking control for air-breathing hypersonic vehicles with actuator constraints." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, no. 14 (November 13, 2016): 2578–93. http://dx.doi.org/10.1177/0954410016675894.

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This paper designs a finite-time output tracking controller for air-breathing hypersonic vehicles (AHVs) subjected to disturbances and actuator constraints. After proper derivations, the original model is divided into two independent subsystems undergoing mismatched lumped disturbance. A finite-time disturbance observer (FTDO) is employed to estimate the lumped disturbance, while an auxiliary system combined with a command pre-filter is designed to analyze the effect of input saturation caused by the restrained actuators. Based on the FTDO and the auxiliary system, a novel integral sliding surface is constructed and then a chattering-free nonsingular controller is developed to realize finite-time output tracking in spite of mismatched lumped disturbance and input saturation, which is its major merit compared with other existing AHV controllers. A simulation study is carried out to verify the proposed control scheme.

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Yang, Guang, Faxing Lu, Ling Wu, and Junfei Xu. "Design of Particle Swarm Optimization Adaptive Sliding Mode Controller Based on an Extended State Observer for the Longitudinal Motion of a Supercavitating Vehicle with Input Saturation." Journal of Sensors 2023 (February 22, 2023): 1–23. http://dx.doi.org/10.1155/2023/2938089.

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The aim of this paper is to present a novel sliding mode control scheme for the supercavitating vehicle trajectory tracking problem that subjects to external disturbances and actuator saturation with two symmetric elevators and a cavitator as actuators by analytical methods and computer simulations. Firstly, the nonlinear and highly coupled dynamic and kinematic models of a supercavitating vehicle are presented in a comprehensive way by taking the cavity memory effect and time-variant planing force into consideration. The PSO algorithm is employed to optimize the control parameters for achieving better and more practical tracking performance by minimizing the objective function. A second-order extended state observer (ESO) is utilized to estimate the unknown external and state-dependent disturbances and compensates for control inputs. In addition, an antiwindup compensator is adopted to cope with actuator saturation. Finally, the proposed control scheme is employed for complex trajectory tracking of a supercavitating vehicle under various conditions by conducting comparative numerical simulations. Rigorous theoretical analysis and simulation results indicate that the proposed control scheme can achieve satisfactory tracking performance and have a good capability of robustness.

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Khatibi, Mahmood, and Mohammad Haeri. "Fault-tolerant control considering time-varying bounds on faults." Transactions of the Institute of Measurement and Control 40, no. 10 (June 26, 2017): 2982–90. http://dx.doi.org/10.1177/0142331217711748.

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This paper presents a novel fault-tolerant control strategy to compensate the time-varying loss of actuators’ effectiveness. It considers intermediate situations where the fault is not determined precisely (unlike active approaches) but overall estimations about its rate and final value are available through the previous experiences and/or experiments. Based on the estimations, two upper and lower time-varying bounds on the actuators’ effectiveness are established to be exploited in the procedure of controller design. In a special case, where these bounds are constant, the method will be reduced to the conventional passive approach. Also, actuator saturation and the effects of [Formula: see text] disturbances are considered in the research. To tackle the conflict between attenuating the effect of L∞ disturbances and enlarging the domain of attraction, a linear matrix inequality optimization framework is suggested. The proposed method is implemented on a model of an unmanned aerial vehicle and the results are discussed.

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Geranmehr, Behdad, Esmaeel Khanmirza, and Shahab Kazemi. "Trajectory control of aggressive maneuver by agile autonomous helicopter." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 4 (February 12, 2018): 1526–36. http://dx.doi.org/10.1177/0954410018755807.

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In this paper, a new state-dependent coefficient parameterization of an agile helicopter dynamics is derived to deal effectively with the optimal trajectory control of aggressive maneuver such as the infinity maneuver with agility. The angular velocity of the main rotor and engine throttle as state and input, respectively, are involved in the dynamic model to improve the maneuvering capability of helicopter. Since the presented six degrees-of-freedom helicopter model is highly nonlinear and nonaffine, particularly nonlinear in actuator, the state-dependent Riccati equation is implemented in the presence of saturation bounds for actuators to achieve precision trajectory control and conquer the challenge of aggressive maneuver tracking control. In addition, new helicopter dynamic representation results in the conventional state-dependent Riccati equation to be applied without prevalent simplifications within dynamic and actuators and also certain augmentations on controllers such as trim or feedforward compensators. Indeed, the proposed controller structure is verified by simulations for both regulation and trajectory tracking problem.

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Félix-Herrán, L. C., D. Mehdi, J. J. Rodríguez-Ortiz, R. Ramírez-Mendoza, and R. Soto. "Takagi-Sugeno Fuzzy Model of a One-Half Semiactive Vehicle Suspension: Lateral Approach." Mathematical Problems in Engineering 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/396305.

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This work presents a novel semiactive model of a one-half lateral vehicle suspension. The contribution of this research is the inclusion of actuator dynamics (two magnetorheological nonlinear dampers) in the modelling, which means that more realistic outcomes will be obtained, because, in real life, actuators have physical limitations. Takagi-Sugeno (T-S) fuzzy approach is applied to a four-degree-of-freedom (4-DOF) lateral one-half vehicle suspension. The system has two magnetorheological (MR) dampers, whose numerical values come from a real characterization. T-S allows handling suspension’s components and actuator’s nonlinearities (hysteresis, saturation, and viscoplasticity) by means of a set of linear subsystems interconnected via fuzzy membership functions. Due to their linearity, each subsystem can be handled with the very well-known control theory, for example, stability and performance indexes (this is an advantage of the T-S approach). To the best of authors’ knowledge, reported work does not include the aforementioned nonlinearities in the modelling. The generated model is validated via a case of study with simulation results. This research is paramount because it introduces a more accurate (the actuator dynamics, a complex nonlinear subsystem) model that could be applied to one-half vehicle suspension control purposes. Suspension systems are extremely important for passenger comfort and stability in ground vehicles.

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Liu, Zhixiang, Chi Yuan, Xiang Yu, and Youmin Zhang. "Fault-Tolerant Formation Control of Unmanned Aerial Vehicles in the Presence of Actuator Faults and Obstacles." Unmanned Systems 04, no. 03 (July 2016): 197–211. http://dx.doi.org/10.1142/s2301385016500060.

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This paper presents a leader-follower type of fault-tolerant formation control (FTFC) methodology with application to multiple unmanned aerial vehicles (UAVs) in the presence of actuator failures and potential collisions. The proposed FTFC scheme consists of both outer-loop and inner-loop controllers. First, a leader-follower control scheme with integration of a collision avoidance mechanism is designed as the outer-loop controller for guaranteeing UAVs to keep the desired formation while avoiding the approaching obstacles. Then, an active fault-tolerant control (FTC) strategy for counteracting the actuator failures and also for preventing the healthy actuators from saturation is synthesized as the inner-loop controller. Finally, a group of numerical simulations are carried out to verify the effectiveness of the proposed approach.

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Zhang, Guilin, Chengjin Zhang, and Jason Gu. "A Memory-Based Hysteresis Model in Piezoelectric Actuators." Journal of Control Science and Engineering 2012 (2012): 1–7. http://dx.doi.org/10.1155/2012/498590.

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A mathematical memory-based model is proposed to capture the hysteresis behavior in piezoelectric actuators. It is observed that the ascending (descending) hysteresis curves are alike and converge to one point without memory saturation. Therefore, two, dominant curves are determined and expressed as continuous functions, and the other hysteresis curves are modeled using two dominant curves through nonlinear transforming of coordinate axis. In the event of memory saturation, a new converging point is used to compensate the model prediction error. The experimental study has been carried out and our proposed model prediction method is compared with PI model and the linear model. It shows that the proposed model prediction method is better than other two methods.

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Chen, B.-S., C.-L. Lin, and F.-B. Hsiao. "Robust Observer-Based Control of a Vibrating Beam." Proceedings of the Institution of Mechanical Engineers, Part C: Mechanical Engineering Science 205, no. 2 (March 1991): 77–89. http://dx.doi.org/10.1243/pime_proc_1991_205_095_02.

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A new multiple-input multiple-output time domain stability criterion for large flexible structures is illustrated by application to observer-based control of a Bernoulli-Euler beam. Upper norm bounds of the state transition matrix of the residual dynamics and total spillover matrix (impulse response matrix of the residual model) are investigated. The approach can be easily extended to a practical consideration of the unavoidable saturation of the actuators and gives an insight into the stabilization analysis of saturating control of flexible structures.

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Moussaoui, L., S. Aouaouda, and R. Rouaibia. "Fault tolerant control of a permanent magnet synchronous machine using multiple constraints Takagi-Sugeno approach." Electrical Engineering & Electromechanics, no. 6 (November 6, 2022): 22–27. http://dx.doi.org/10.20998/2074-272x.2022.6.04.

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Introduction. Fault diagnosis, and fault tolerant control issues are becoming very important to ensure a good supervision of systems and guarantee the safety of human operators and equipments even if system complexity increases. Problem. In fact, the presence of faults in actuators, sensors and processes can lead to system performance degradation, system breakdown, economic loss, and even disastrous situations. Furthermore, Actuator saturation or control input saturation is probably the most usual nonlinearity encountered in control engineering because of the physical impossibility of applying unlimited control signals and/or safety constraints. Purpose. This article is dedicated to the problem of fault tolerant control for constrained nonlinear systems described by a Takagi-Sugeno model. One of the interests of this type of models is the possibility of extend some tools and methods from linear system case to the nonlinear one. The novelty of the work consists in developing a fault tolerant control algorithm for a nonlinear Permanent Magnet Synchronous Machine model using an observer based state-feedback control technique in order to enhance fault and state estimation despite actuator saturation and system disturbances. Methods. Indeed a sensor fault detection observer based residual generator is synthesized with a guaranteed L2 performance to attenuate the external disturbances effect from one side and to maximize the residual sensitivity to faults from the other side. Based on Lyapunov function, design conditions are formulated in terms of Linear Matrix Inequalities to ensure stability of the global system. Practical value. A detailed study concerning nonlinear permanent magnet synchronous machine model, which is consolidated by simulation results, is conducted to show the used algorithm’s effectiveness guarantying fault estimation and reconfiguration of the control law to maintain stable performance even in the presence of actuator faults, external perturbation and the phenomenon of actuator saturation.

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XIAO, JIN-ZHUANG, HONG-RUI WANG, and HONG-BIN WANG. "KNOWLEDGE BASED ROBOTIC CONTROL AGAINST SATURATION OF ACTUATORS OWING TO FUZZY RULES." International Journal of Pattern Recognition and Artificial Intelligence 22, no. 01 (February 2008): 183–94. http://dx.doi.org/10.1142/s0218001408006107.

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Considering the decreasing performance of robotic systems under the constraints of actuators, this paper concludes the rules of dynamic control process and extracts the knowledge of optimizing the output of robotic controller based on the analysis of a Lyapunov function. Then fuzzy rules are used to express the knowledge and embedded in the controller to direct the dynamic control process. Under this controller, the systemic requirement of high-level outputs of the actuators is limited to a great extent, at the same time the convergent performance is optimized by a fuzzy-sets method from which the saturated fault tolerant control is realized in robotic manipulators. Simulating results on a 2-DOF robot validate the effectiveness of the given controller.

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Wu, Wen-Juan, and Guang-Ren Duan. "Gain scheduled control of linear systems with unsymmetrical saturation actuators." International Journal of Systems Science 47, no. 15 (December 7, 2015): 3711–19. http://dx.doi.org/10.1080/00207721.2015.1117157.

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Baldini, Alessandro, Riccardo Felicetti, Alessandro Freddi, and Andrea Monteriù. "Fault-Tolerant Control of a Variable-Pitch Quadrotor under Actuator Loss of Effectiveness and Wind Perturbations." Sensors 23, no. 10 (May 19, 2023): 4907. http://dx.doi.org/10.3390/s23104907.

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The actuator fault-tolerant control problem for a variable-pitch quadrotor is addressed under uncertain conditions. Following a model-based approach, the plant nonlinear dynamics are faced with a disturbance observer-based control and a sequential quadratic programming control allocation, where only kinematic data of the onboard inertial measurement unit are required for the fault-tolerant control, i.e., it does not require the measurement of the motor speed nor the current drawn by the actuators. In the case of almost horizontal wind, a single observer handles both faults and the external disturbance. The estimation of the wind is fed forward by the controller, while the actuator fault estimation is exploited in the control allocation layer, which copes with the variable-pitch nonlinear dynamics, thrust saturation, and rate limits. Numerical simulations in the presence of measurement noise show the capability of the scheme to handle multiple actuator faults in a windy environment.

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Kchaou, Mourad, Mohamed Amine Regaieg, Houssem Jerbi, Rabeh Abbassi, Dan Stefanoiu, and Dumitru Popescu. "Admissible Control for Non-Linear Singular Systems Subject to Time-Varying Delay and Actuator Saturation: An Interval Type-2 Fuzzy Approach." Actuators 12, no. 1 (January 7, 2023): 30. http://dx.doi.org/10.3390/act12010030.

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Applied in many fields, nonlinear systems involving delay and algebraic equations are referred to as singular systems. These systems remain challenging due to saturation constraints that affect actuators and cause harm to their operation. Furthermore, the complexity of the problem will increase when uncertainty also simultaneously affects the system under consideration. To address this issue, this paper investigated a feasible control strategy for nonlinear singular systems with time-varying delay that are subject to uncertainty and actuator saturation. The IT-2 fuzzy model was adopted to describe the dynamic of the non-linear delayed systems using lower and upper membership functions to deal with the uncertainty. Moreover, the polyhedron model was applied to characterize the saturation function. The goal of the control approach was to design a relevant IT2 fuzzy state feedback controller with mismatched membership functions so that the closed-loop system is admissible. On the basis of an appropriate Lyapunov–Krasovskii functional, sufficient delay-dependent conditions were established and an optimization problem was formulated in terms of linear matrix inequality constraints to optimize the attraction domain. Simulation examples are provided to verify the effectiveness of the proposed method.

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Guay, Martin, and Daniel J. Burns. "Extremum Seeking Control for Discrete-Time with Quantized and Saturated Actuators." Processes 7, no. 11 (November 8, 2019): 831. http://dx.doi.org/10.3390/pr7110831.

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This paper proposes an extremum-seeking controller (ESC) design for a class of discrete-time nonlinear control systems subject to input constraints or quantized inputs. The proposed method implements a proportional-integral ESC design along with a discrete-time anti-windup mechanism. The anti-windup enforces input saturation while preserving the input dither signal. The technique incorporates a mechanism for adjusting the amplitude of the extremum seeking control dither signal. This mechanism ensures that any violation of constraints due to the dither signal is removed while maintaining the probing signal active. An amplitude update routine is also proposed. The amplitude update is coupled with a saturation bias estimation algorithm that correctly accounts for the inherent bias associated with systems operated at or near saturation conditions. The amplitude update is designed to remove the dither signal when the system approaches the optimum. It also ensures that a lower bound of the amplitude is enforced to guarantee that excitation conditions are maintained.

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Guo, Jishu, and Guohui Tian. "Mechanical design and robust tracking control of a class of antagonistic variable stiffness actuators based on the equivalent nonlinear torsion springs." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 232, no. 10 (June 22, 2018): 1337–55. http://dx.doi.org/10.1177/0959651818781272.

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The novel conceptual model of the antagonistic variable stiffness actuator based on the equivalent nonlinear torsion spring and the friction damper is demonstrated. For the dynamic model of the antagonistic variable stiffness actuator in the presence of parametric uncertainties, unknown bounded friction torques, unknown bounded external disturbance, and input saturation constraints, using the coordinate transformation, the state space model of the antagonistic variable stiffness actuator with composite disturbances and input saturation constraints is transformed into an extended integral chain–type pseudo-linear system with input saturation constraints. Subsequently, a combination of the linear extended state observer, sliding mode control, and adaptive input saturation compensation law is adopted for the design of the robust tracking controller that simultaneously regulates the position and stiffness of the antagonistic equivalent nonlinear torsion spring-based variable stiffness actuator. Under the proposed controller, the semi-global uniformly ultimately bounded stability of the closed-loop system has been proved via Lyapunov stability analysis. Simulation studies demonstrate the effectiveness and the robustness of the proposed robust adaptive tracking control method for the antagonistic variable stiffness actuator.

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Nguyen, Ngoc Phi, Nguyen Xuan Mung, Le Nhu Ngoc Thanh Ha, and Sung Kyung Hong. "Fault-Tolerant Control for Hexacopter UAV Using Adaptive Algorithm with Severe Faults." Aerospace 9, no. 6 (June 3, 2022): 304. http://dx.doi.org/10.3390/aerospace9060304.

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In this paper, a fault-tolerant control method is proposed for a hexacopter under uncertainties. The proposed method is based on adaptive-sliding-mode control (ASMC) and a control allocation scheme. First, a mathematical model of the hexacopter is employed with model uncertainties. Next, the control allocation strategy is combined with ASMC to handle actuator faults, which can distribute the virtual control signal to redundant actuators. A modified fault-tolerant control is proposed to overcome this virtual input saturation. Finally, the system stability is validated using the Lyapunov theory. The performance of the proposed method is compared with that of normal ASMC. The simulation results show that the suggested strategy can realize quicker compensation under faulty conditions.

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Ruiz, Adrián, Damiano Rotondo, and Bernardo Morcego. "Design of State-Feedback Controllers for Linear Parameter Varying Systems Subject to Time-Varying Input Saturation." Applied Sciences 9, no. 17 (September 2, 2019): 3606. http://dx.doi.org/10.3390/app9173606.

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All real-world systems are affected by the saturation phenomenon due to inherent physical limitations of actuators. These limitations should be taken into account in the controller’s design to prevent a possibly severe deterioration of the system’s performance, and may even lead to instability of the closed-loop system. Contrarily to most of the control strategies, which assume that the saturation limits are constant in time, this paper considers the problem of designing a state-feedback controller for a system affected by time-varying saturation limits with the objective to improve the performance. In order to tie variations of the saturation function to changes in the performance of the closed-loop system, the shifting paradigm is used, that is, some parameters scheduled by the time-varying saturations are introduced to schedule the performance criterion, which is considered to be the instantaneous guaranteed decay rate. The design conditions are obtained within the framework of linear parameter varying (LPV) systems using quadratic Lyapunov functions with constant Lyapunov matrices and they consist in a linear matrix inequality (LMI)-based feasibility problem, which can be solved efficiently using available solvers. Simulation results obtained using an illustrative example demonstrate the validity and the main characteristics of the proposed approach.

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Pană, Valentin. "Pilot-Induced Oscillations Prevention Using Anti-Windup Compensation in the Presence of Time-Delay." Applied Mechanics and Materials 325-326 (June 2013): 1262–66. http://dx.doi.org/10.4028/www.scientific.net/amm.325-326.1262.

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The paper presents a compensator design technique for systems with saturating actuators in order to recover as much as possible the performance of the unsaturated case. This anti-windup scheme is obtained using H-infinity optimization methodology. The proposed design approach allows to obtain a anti-windup controller that accounts for time-delays in the control system. Comparative result are presented for the two design methods and time simulation of the nonlinear system are used to analyze the performances of both designs. A reduced order anti-windup controller procedure is also investigated. Keywords: PIO, anti-windup, rate saturation, compensator.

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Pak, H. A., and P. J. Turner. "Optimal Tracking Controller Design for Invariant Dynamics Direct-Drive Arms." Journal of Dynamic Systems, Measurement, and Control 108, no. 4 (December 1, 1986): 360–65. http://dx.doi.org/10.1115/1.3143807.

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This paper presents an optimal solution to the problem of tracking controller design for a category of direct-drive robot arms, mechanically constructed to have invariant and decoupled joint actuator dynamics. The controller acts on joint actuators consisting of d.c. servo motors driven via servo amplifiers containing an analog current feedback loop. For good tracking behavior, the controller uses future reference positions of a joint to anticipate the changes in reference velocity. An explicit acceleration feedforward term is avoided improving the power to noise ratio of the control signal. For good regulation behavior, the controller uses position and velocity feedback. An integral of error term is also avoided, reducing the probability of the occurrence of limit cycle oscillations caused by saturation of the actuator torque rating. The correlations between the classical and the optimal design parameters are discussed using transient response analysis followed by experimental observations.

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Dong, Zhenle, Dawei Ma, Qi Liu, and Xin Yue. "Motion control of valve-controlled hydraulic actuators with input saturation and modelling uncertainties." Advances in Mechanical Engineering 10, no. 11 (November 2018): 168781401881227. http://dx.doi.org/10.1177/1687814018812273.

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This article mainly concerns the high-performance motion control of valve-controlled hydraulic actuators with input saturation and modelling uncertainties. The nonlinear mathematic model including a continuously differentiable static friction model is constructed, and then adaptive robust design framework is adopted to cope with the modelling uncertainties, which always impede the progress of high-performance motion controller. Input saturation, which frequently exists in most physical systems, has been found to be prone to performance decay. To address this specific issue, an embedded anti-windup block containing two adjusting mechanisms is properly designed to improve the motion controller to ensure the stability and performance preservation in circumstance of input saturation, which is proved via rigorous Lyapunov analysis. Typical simulation is implemented to illustrate the availability of the proposed control method.

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SAIFIA, D., M. CHADLI, and S. LABIOD. "Static Output Feedback Stabilization of Multiple Models Subject to Actuators Saturation." IFAC Proceedings Volumes 43, no. 8 (2010): 534–39. http://dx.doi.org/10.3182/20100712-3-fr-2020.00087.

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Seuret, Alexandre, and Joao M. Gomes Da Silva. "Networked control: taking into account sample period variations and actuators saturation." IFAC Proceedings Volumes 44, no. 1 (January 2011): 14501–6. http://dx.doi.org/10.3182/20110828-6-it-1002.01058.

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Lindner, Douglas K., Gregory A. Zvonar, and Dusan Borojevic. "Performance and control of proof-mass actuators accounting for stroke saturation." Journal of Guidance, Control, and Dynamics 17, no. 5 (September 1994): 1103–8. http://dx.doi.org/10.2514/3.21316.

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Mahmoud, Mufeed, Jin Jiang, and Youmin Zhang. "STABILITY OF FAULT TOLERANT CONTROL SYSTEMS DRIVEN BY ACTUATORS WITH SATURATION." IFAC Proceedings Volumes 35, no. 1 (2002): 473–78. http://dx.doi.org/10.3182/20020721-6-es-1901.01150.

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Li, Yanzhou, Yuanqing Wu, and Shenghuang He. "Synchronization of Network Systems Subject to Nonlinear Dynamics and Actuators Saturation." Circuits, Systems, and Signal Processing 38, no. 4 (September 20, 2018): 1596–618. http://dx.doi.org/10.1007/s00034-018-0940-3.

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Mihankhah, Amin, and Ali Doustmohammadi. "Adaptive neural-based finite-time attitude synchronization and tracking control of multiple rigid bodies under actuator faults and saturation." Aircraft Engineering and Aerospace Technology 94, no. 3 (November 22, 2021): 407–17. http://dx.doi.org/10.1108/aeat-10-2020-0219.

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Purpose The purpose of this paper, is to solve the problem of finite-time fault-tolerant attitude synchronization and tracking control of multiple rigid bodies in presence of model uncertainty, external disturbances, actuator faults and saturation. It is assumed that the rigid bodies in the formation may encounter loss of effectiveness and/or bias actuator faults. Design/methodology/approach For the purpose, adaptive terminal sliding mode control and neural network structure are used, and a new sliding surface is proposed to guarantee known finite-time convergence not only at the reaching phase but also on the sliding surface. The sliding surface is then modified using a proposed auxiliary system to maintain stability under actuator saturation. Findings Assuming that the communication topology between the rigid bodies is governed by an undirected connected graph and the upper bounds on the actuators’ faults, estimation error of model uncertainty and external disturbance are unknown, not only the attitudes of the rigid bodies in the formation are synchronized but also they track the time-varying attitude of a virtual leader. Using Lyapunov stability approach, finite-time stability of the proposed control algorithms demonstrated on the sliding phase as well as the reaching phase. The effectiveness of the proposed algorithm is also validated by simulation. Originality/value The proposed controller has the advantage that the need for any fault detection and diagnosis mechanism and the upper bounds information on estimation error and external disturbance is eliminated.

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Zhou, X., and A. Chattopadhyay. "Hysteresis Behavior and Modeling of Piezoceramic Actuators." Journal of Applied Mechanics 68, no. 2 (August 28, 2000): 270–77. http://dx.doi.org/10.1115/1.1357168.

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A new theory is developed to model the hysteresis relation between polarization and electric field of piezoceramics. An explicit formulation governing the hysteresis is obtained by using saturation polarization, remnant polarization, and coercive electric field. A new form of elastic Gibbs energy is proposed to address the coupling relations between electrical field and mechanical field. The nonlinear constitutive relations are derived from the elastic Gibbs energy and are applicable in the case of high stroke actuation. The hysteresis relations obtained using the current model are correlated with experimental results. The static deflection of a cantilever beam with surface-bonded piezoelectric actuators is analyzed by implementing the current constitutive relations. Numerical results reveal that hysteresis is an important issue in the application of piezoceramics.

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Graber, V., and E. Schuster. "Nonlinear burn control in ITER using adaptive allocation of actuators with uncertain dynamics." Nuclear Fusion 62, no. 2 (February 1, 2022): 026016. http://dx.doi.org/10.1088/1741-4326/ac3cd8.

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Abstract ITER will be the first tokamak to sustain a fusion-producing, or burning, plasma. If the plasma temperature were to inadvertently rise in this burning regime, the positive correlation between temperature and the fusion reaction rate would establish a destabilizing positive feedback loop. Careful regulation of the plasma’s temperature and density, or burn control, is required to prevent these potentially reactor-damaging thermal excursions, neutralize disturbances and improve performance. In this work, a Lyapunov-based burn controller is designed using a full zero-dimensional nonlinear model. An adaptive estimator manages destabilizing uncertainties in the plasma confinement properties and the particle recycling conditions (caused by plasma–wall interactions). The controller regulates the plasma density with requests for deuterium and tritium particle injections. In ITER-like plasmas, the fusion-born alpha particles will primarily heat the plasma electrons, resulting in different electron and ion temperatures in the core. By considering separate response models for the electron and ion energies, the proposed controller can independently regulate the electron and ion temperatures by requesting that different amounts of auxiliary power be delivered to the electrons and ions. These two commands for a specific control effort (electron and ion heating) are sent to an actuator allocation module that optimally maps them to the heating actuators available to ITER: an electron cyclotron heating system (20 MW), an ion cyclotron heating system (20 MW), and two neutral beam injectors (16.5 MW each). Two different actuator allocators are presented in this work. The first actuator allocator finds the optimal mapping by solving a convex quadratic program that includes actuator saturation and rate limits. It is nonadaptive and assumes that the mapping between the commanded control efforts and the allocated actuators (i.e. the effector model) contains no uncertainties. The second actuator allocation module has an adaptive estimator to handle uncertainties in the effector model. This uncertainty includes actuator efficiencies, the fractions of neutral beam heating that are deposited into the plasma electrons and ions, and the tritium concentration of the fueling pellets. Furthermore, the adaptive allocator considers actuator dynamics (actuation lag) that contain uncertainty. This adaptive allocation algorithm is more computationally efficient than the aforementioned nonadaptive allocator because it is computed using dynamic update laws so that finding the solution to a static optimization problem is not required at every time step. A simulation study assesses the performance of the proposed adaptive burn controller augmented with each of the actuator allocation modules.

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Wu, Yuan-Qing, Zheng-Guang Wu, and Hongye Su. "Synchronisation control of dynamical networks subject to variable sampling and actuators saturation." IET Control Theory & Applications 9, no. 3 (February 5, 2015): 381–91. http://dx.doi.org/10.1049/iet-cta.2014.0383.

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Zheng, Zewei, Cheng Jin, Ming Zhu, and Kangwen Sun. "Trajectory tracking control for a marine surface vessel with asymmetric saturation actuators." Robotics and Autonomous Systems 97 (November 2017): 83–91. http://dx.doi.org/10.1016/j.robot.2017.08.005.

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Journal articles on the topic 'Actuators Saturation'

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