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IET control theory & applications
Institution of Engineering and Technology
IET control theory & applications

Institution of Engineering and Technology

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1751-8644

IET control theory & applications/Journal IET control theory & applications
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    Adaptive prescribed performance terminal sliding mode attitude control for quadrotor under input saturation

    Gang XuYuanqing XiaDi-Hua ZhaiDailiang Ma...
    2473-2480页
    查看更多>>摘要：This study investigates the attitude tracking problem of quadrotor in presence of external disturbances and the constraint of input saturation. An adaptive prescribed performance terminal sliding mode control scheme is proposed. Terminal sliding mode control algorithm guarantees all state variables to converge to their desired value in a short time while prescribed performance function limits the convergence speed, maximum overshoot and steady-state error. Adaptive law is adopted to estimate the unknown upper bound of external disturbances. To further address input saturation problem encountered in practical system, an auxiliary system is designed. Lyapunov stability approach is applied to guarantee the stability of the closed-loop system. Finally, Numerical simulations with non-linear model are presented to demonstrate the effectiveness and superiority of the proposed control scheme.
      原文链接:
    • NETL
    • NSTL
    • Inst Engineering Technology-Iet

    First-order plus time-delay systems under the effects of actuator rate limit

    Jie YuanJie HanLin ChaiShumin Fei...
    2481-2490页
    查看更多>>摘要：Actuator rate limit phenomenon is ubiquitous in control systems, but it has always been neglected in practical engineering. Especially, few papers are published to investigate the system identification while considering the rate limit. Step function is commonly used in parameter estimation and its first-order derivative at the step time goes to infinity, which is not affordable by real actuators. As a result, the rate limit slows down the system response speed, misleads the parameter identification, and subsequently affects the controller design and deteriorates the control performance. This study proposes both graphical method and curve fitting method to identify the first-order plus time-delay (FOPTD) systems with consideration of the actuator rate limit effect whose limit value is unknown. Quantitative analyses of the parameter mismatch in the traditional FOPTD model and parameter sensitivity analyses are also carried out. Both simulation results and experimental results have shown the necessity and feasibility of defining a new model structure which includes the rate limit value.
      原文链接:
    • NETL
    • NSTL
    • Wiley

    Distributed fusion estimation for non-linear networked systems with random access protocol and cyber attacks

    Jiyong LuWeizhen WangLi LiYanping Guo...
    2491-2498页
    查看更多>>摘要：This study investigates the distributed fusion estimation problem for multi-sensor non-linear networked systems with random access protocol (RAP) and cyber attacks. For each sensor, the RAP is applied to determine which channel can enter the communication networks at each transmission instant. The process of transmitting measurements to a corresponding local estimator (LE) via the wireless network may be attacked by a vicious attacker. Hence, a detector based on cross-correlation of the causal sequence is proposed in the LE. Moreover, a distributed fusion estimation algorithm based on a sequential covariance intersection fusion technique is designed utilising local estimations calculated by modified unscented Kalman filter. A sufficient condition is obtained to guarantee the boundedness of fusion estimation error. Finally, a numerical simulation is given to demonstrate the effectiveness of the theoretical results.
      原文链接:
    • NETL
    • NSTL
    • Inst Engineering Technology-Iet

    Consensus of multi-agent system based on novel avoidance function and unequal avoidance strategy

    Yakun ZhuHaoran LiHongjun Duan
    2499-2506页
    查看更多>>摘要：In practice, the energy of an agent is limited, therefore, saving energy is an important problem in the practical applications of multi-agent systems. For this problem, the authors firstly proposes a novel collision avoidance function, which have much less energy cost than the normal potential field function. Secondly, to further reduce energy cost, the authors propose an unequal collision avoidance strategy, that is, according to the residual energy of neighbouring agents, high-energy agent performs collision avoidance, while the low-energy agent does not. Thirdly, the controller is designed based on the novel collision avoidance function and the unequal collision avoidance strategy. Besides the consensus and collision avoidance can be achieved, the proposed controller can also effectively extend the operation time/range of the whole system. Finally, the simulations verify the effectiveness and superiority of the proposed controller.
      原文链接:
    • NETL
    • NSTL
    • Inst Engineering Technology-Iet

    Stability and ℓ∞-gain analysis for discrete-time positive singular systems with unbounded time-varying delays

    Dinh Cong HuongNguyen Huu Sau
    2507-2513页
    查看更多>>摘要：This study considers the stability and <inline-formula/>-gain analysis problem for discrete-time positive singular systems with unbounded time-varying delays. By proposing some new techniques and employing mathematical induction method, the authors first derive a sufficient condition to analyse the stability of the system. The authors then investigate the <inline-formula/>-gain by exploiting the monotonicity of state trajectory. They show that the <inline-formula/>-gain for the considered systems is independent of the magnitude of delays and fully determined by the system matrices. The validity of the theoretical results is demonstrated by a numerical example.
      原文链接:
    • NETL
    • NSTL
    • Wiley

    Dynamic event-triggered cooperative formation control for UAVs subject to time-varying disturbances

    Lili WeiMou ChenTao Li
    2514-2525页
    查看更多>>摘要：The dynamic event-triggered cooperative formation control problem for unmanned aerial vehicles (UAVs) subject to time-varying disturbances is studied. A single UAV is described by a second-order kinematical model and the desired formation is constructed by utilising the leader–follower framework, in which the leader UAV provides the desired trajectory for each follower. Unknown external disturbances are assumed to be composed of multiple frequency waves and appropriate disturbance observers are designed. A dynamic event-triggered mechanism is proposed with its triggering threshold being dynamically adjustable rather than a fixed constant, which can reduce data transmissions more effectively and meanwhile avoid the Zeno behaviour. Then a distributed event-triggered control scheme is developed for the UAV formation and two sufficient conditions on asymptotical stability of the resulting closed loop system are derived. Furthermore, controller gains, observer gains, and triggering parameters can be jointly obtained by solving the desired linear matrix inequality (LMI). Finally, a simulated example is given to illustrate the obtained results.
      原文链接:
    • NETL
    • NSTL
    • Inst Engineering Technology-Iet

    Data filtering-based recursive identification for an exponential autoregressive moving average model by using the multi-innovation theory

    Huan XuFengying MaFeng DingLing Xu...
    2526-2534页
    查看更多>>摘要：This study employs the data filtering technique to investigate the recursive identification problems for a non-linear exponential autoregressive model with moving average noise, i.e. the ExpARMA model. Whitening the ExpARMA model by a linear filter, the original identification model is divided into a filtered identification model and a coloured noise model, then a filtering-based extended stochastic gradient algorithm is derived. In order to improve the parameter estimation accuracy, the multi-innovation identification theory is used to develop a filtering-based multi-innovation extended stochastic gradient algorithm for the ExpARMA model. A simulation example is given to demonstrate the superiority of the proposed filtering-based multi-innovation algorithm over the existing algorithms.
      原文链接:
    • NETL
    • NSTL
    • Wiley

    Trade-off between power extraction maximisation and fatigue reduction in wind farms via second-order sliding mode control and min–max optimisation

    Elisa CapelloTakayuki WadaElisabetta PuntaYasumasa Fujisaki...
    2535-2547页
    查看更多>>摘要：In the last 10 years, with the increase of renewable energies, great attention is devoted to operation and maintenance of wind turbines and wind farms, which are the fundamental objectives to be guaranteed by the design of control systems. This study proposes a trade-off approach between fatigue reduction and power extraction for wind farm scenarios. The focus of this approach is to reduce maintenance costs for fatigue loads. This issue is solved by an optimisation problem, in which the maximum fatigue load among the turbines in the wind farm is minimised, then pitch angle and tip-speed ratio are given as reference points for each turbine in the wind farm. Furthermore, the super-twisting sliding mode algorithm is used for the rotor speed control and it shows that the turbines work at the optimised operating points. Moreover, the sliding mode controller produces continuous torques and improves the wind turbine performance by enhancing energy capture and reducing dynamic loads. The effectiveness of the method is illustrated through simulations of two wind farm scenarios. The results obtained with the proposed approach are compared with the case when each turbine in the wind farm tracks the maximum power operating point.
      原文链接:
    • NETL
    • NSTL
    • Inst Engineering Technology-Iet

    Non-linear estimation and observer-based output feedback control

    Y. BatmaniS. Khodakaramzadeh
    2548-2555页
    查看更多>>摘要：In this study, a new observer is proposed for a class of non-linear systems which is based on an output-dependent Riccati equation. Necessary conditions for convergence of the state estimation to the system state are investigated through a theorem. Then, based on the proposed observer, two techniques are developed to solve non-linear stabilisation and non-linear tracking problems. It is shown that the separation principle between the estimation and control holds. Indeed, just like a linear system, a decentralised observer-based state feedback controller can be designed for the non-linear system while the stability of the closed-loop system is guaranteed. For the tracking problem, it is proved that the closed-loop system states converge asymptotically to the states of the desired model. Numerical simulations are given to demonstrate the effectiveness of the proposed observer and the observer-based controllers.
      原文链接:
    • NETL
    • NSTL
    • Wiley

    Fractional-order adaptive non-singular fast terminal sliding mode control with time delay estimation for robotic manipulators

    Yangyang ZhangXiaohui YangPeng WeiPeter Xiaoping Liu...
    2556-2565页
    查看更多>>摘要：In this study, an adaptive fractional-order non-singular fast terminal sliding mode (FO-NFTSM) scheme based on time delay estimation (TDE) is proposed for the control of robotic manipulators. A new FO-NFTSM surface with a continuous TSM-type switch item is designed to ensure good performance, such as fast finite-time convergence, high precision and being non-singular. The chattering problem is solved by introducing a saturation function into the control signal. The TDE element is used to estimate the robot's unknown dynamic parameters and external disturbances. The Lyapunov stability theory is used to prove the finite-time stability of the control system. The proposed control algorithm is applied to a two-link robotic manipulator and the comparative results verify the effectiveness and superiority of the proposed control approach in comparison with existing control methods.
      原文链接:
    • NETL
    • NSTL
    • Inst Engineering Technology-Iet