IET Control Theory and Applications最新文献

For a class of full-states constraints nonlinear system with actuator failure, an adaptive fuzzy disturbance observer tracking design is carried out by using Lyapunov function and the dynamic surface method. The integral explosion problem is avoided by using the dynamic surface design method. Because the disturbance of the system is unknown, a nonlinear fuzzy disturbance observer is designed to estimate the unknown disturbance. And the unknown nonlinear function is approximated fuzzy logic systems. Based on the Lyapunov function method and backstepping approach, the stability of considered systems are analysed. And the proposed method can guarantee that all the signals in the closed-loop system are bounded and the system output can track the desired signal to the small neighbourhood range. In addition, the fuzzy disturbance observer can estimate the unknown disturbance state well. Finally, several sets of simulation examples are given and compared with other method, and the experimental results are quantitatively analysed. Then, the robustness and superiority of the proposed control scheme are verified and demonstrated.

This article proposes a novel approach for designing a mode-dependent $�H_{\infty }$ full-order dynamic filter for a cyber-physical system (CPS) that is subject to polytopic uncertainties. The CPS operates on an unreliable network that is susceptible to transmission failures and Denial of Service (DoS) attacks. The attackers have limited energy resources, and the duration of the DoS attack is limited to a maximum number of consecutive time instants. The network is modeled after a proposed non-homogeneous Markov chain whose transition probability matrix may feature uncertain and unknown probabilities, which are dependent on time-varying parameters. The design conditions for the filter are obtained using parameter-dependent linear matrix inequalities. The proposed filter is shown to be effective in reducing the impact of DoS attacks and transmission failures on the CPS. Numerical experiments are presented to illustrate the efficacy of the proposed filter design method, demonstrating its ability to mitigate the effects of uncertainties and attacks on the CPS.

An inerter-based dynamic vibration absorber (IDVA) is proposed and applied to suppress the vibration of a plate. The dynamic model of a thin rectangular plate attached with an IDVA is established and the frequency response function of the transverse displacement of the plate is derived through the classical vibration theory and the analysis in the $�s$ domain. In addition, the equation for frequency ratios of fixed points is obtained, and the condition for the existence of four fixed points is found by investigating the problem of solving quartic equations. Moreover, the extended fixed-point method is employed to analytically obtain the optimal parameters of the IDVA attached to a plate, the expressions of the optimal damping ratio and other dimensionless qualities are presented.

This work tackles the tracking control problem of robotic manipulators where the robot dynamics contains uncertain parameters and joint velocity measurements are not available. Specifically when the robotic manipulator is required to perform a periodic task repetitively, as in most industrial applications, a repetitive learning controller is proposed that does not require joint velocity measurements and can compensate the uncertainties of the robot dynamical parameters and additive disturbances caused due to the periodic joint motion. The proposed solution is achieved via the use of a novel learning component in the controller design in conjunction with a novel model-free joint velocity observer design. The stability of the closed-loop system and the convergence of both the joint position tracking error and the joint velocity observation error to the origin are guaranteed via Lyapunov based arguments. Experimental results performed on a 2 degree of freedom robot manipulator are presented to demonstrate the performance of the proposed observer–controller couple.

This study investigates the global adaptive prescribed performance control (PPC) of a class of uncertain strict-feedback nonlinear systems with sensor faults based on the switching periodic event-triggering mechanism (SPETM). Due to the existence of sensor faults, the controlled system is first remodeled by utilizing the available variables. To reduce the communication frequency, a novel SPETM is proposed by combining the advantages of the static and the dynamic event-triggering mechanisms. This mechanism can not only avoid continuously monitoring the event-triggering condition and avoid the Zeno phenomenon in mechanism, but also reduce the trigger frequency while ensuring the system performance by adjusting the event-triggering threshold dynamically. Meanwhile, a time-varying scaling function, whose reciprocal is considered as a prescribed performance function, is designed to achieve the global PPC by combining the nonlinear transformation technique. The adaptive control algorithm design is completed by employing the backstepping methodology, which can guarantee that all closed-loop signals are bounded and the actual system output signal evolves within the prescribed performance boundary for arbitrary initial values. The effectiveness and the advantages of the proposed control algorithm are illustrated through an application example of the network-based robotic manipulator system.

In industrial process control, the proportional–integral–derivative (PID) control scheme is well-recognized and widely utilized. However, due to the distinctive characteristics of real systems, their control design primarily aims at achieving optimal production performance, constrained by uncertainty and variations. This paper initially discusses a database-driven PID (DD-PID) control scheme that was previously proposed. This scheme combines the DD-PID with the cerebellar model articulation control to minimise computational and memory requirements for industrial application. Subsequently, a hydraulic system is introduced, detailing its characteristics and control necessities. Furthermore, both the DD-PID and the proposed cerebellar model articulation control memory-based DD-PID control schemes are implemented and evaluated through experimental examples on a hydraulic system. Lastly, as a practical validation of the theoretical approach, a quantitative assessment compares the two methods, discussing the practicality and efficacy of the proposed scheme in reducing computation and memory consumption.

Formation control is a fundamental task in the realm of autonomous multiagent systems. To drive a group of agents to maneuver continuously with the desired formation, this paper studies the finite-time affine formation control problem with disturbances, input constraints and safety guarantee. A non-singular terminal sliding mode control (NTSMC) is implemented to achieve finite-time convergence of all followers to their desired positions. Additionally, an auxiliary system is deployed to address input constraints resulting from the physical properties of the affine formation system. To mitigate the impact of lumped disturbances, a finite-time disturbance observer (FTDO) is employed to estimate the disturbances and compensate for their effects. Based on FTDO, the auxiliary system and the above NTSMC, a finite-time robust controller is developed as the nominal controller. By modifying the nominal controllers to comply with safety constraints, control barrier functions are employed to ensure the safety of the formation system in obstacle-filled environment. Finally, the effectiveness and feasibility of this method are validated through simulations and real-world experiments.

In this paper, an improved zeroing neural network (ZNN) model is proposed to obtain the positive definite solutions of the continuous coupled Lyapunov matrix equations (CLMEs) associated with continuous-time Markovian jump (CMJ) systems. To achieve this, a general ZNN model is established by constructing a matrix-valued error function. Then, to accelerate the convergence rate of the proposed ZNN model, the latest estimation is introduced to obtain an improved ZNN model. Some convergence conditions have been derived for the presented improved ZNN model through Lyapunov theory. Comparisons among the improved ZNN model and the existing results are conducted to illustrate the advantages of the proposed improved ZNN model in numerical examples.

This study addresses the state estimation problem of discrete-time non-linear stochastic systems with non-Gaussian noises, particularly impulsive noises. Instead of minimizing the mean square error of the state estimate, which tends to excessively focus on outliers caused by non-Gaussian noises, the $�{\ell }_1$ norm-based non-linear recursive filter (L1KF) is put forward in this paper. Here, minimizing the $�{\ell }_1$ norm of model errors is actually to pursue the minimum sum of absolute values of all errors, which is equitable to all model errors rather than paying much attention on outliers. To further improve estimation accuracy, a recursive nonlinear smoother (L1KS) is proposed, based on minimizing the $�{\ell }_1$ norm of model errors. The proposed $�{\ell }_1$ norm-based filter and smoother are implemented using unscented transformation for statistical linear regression applied to nonlinear models. Additionally, the computational complexity of the proposed method is analysed. Simulation results of tracking a radar target with impulsive noises demonstrate the effectiveness and robustness of the proposed estimator.

For enhancing the load torque synchronization performance of dual-driven systems, the inherent coupling effect between the parallel axes is analyzed first and could be described as two distinct components of the synchronous error. Thus, the feedforward-feedback composite synchronous control scheme is proposed in this paper to eliminate these desynchronization factors. Secondly, the selection of synchronization objectives such as speeds, positions or currents of parallel axes is analyzed, which may not accurately reflect the actual load desynchronization due to mismatch dynamics. To overcome this drawback, the synchronous feedback controller is modified by incorporating a load torque observer, which can provide good adaptation to modelling errors, disturbances and eliminate the load desynchronization effectively. Simulation and experimental results demonstrate significant improvement in load torque synchronization performance achieved by the proposed control scheme.