Asian Journal of Control最新文献

The dynamic event-triggered decentralized adaptive fault-tolerant control strategy is designed for nonlinear interconnected systems with time delay and unknown control directions. The dynamic event-triggered control scheme where the threshold parameters related to measurement errors are dynamically adjusted by introducing adaptive laws into the control law appropriately increases the time interval for controller update. Then, the Nussbaum function and linear transformation are employed to handle the coupling problem caused by actuator faults and unknown control directions. Meanwhile, the Lyapunov–Krasovskii function is utilized to compensate the effect of time delay and guarantees that all closed-loop signals are bounded. The errors converge into bounded compact sets around the origin. The validity of the presented scheme is verified via a simulation example.

In this paper, a class of single-master-multiple-slaves (SMMS) bilateral teleoperation systems with the limitation of communication bandwidth is investigated. The signals are exchanged between the master and the slaves through delayed communication. Besides, to avoid data collisions, the Try-Once-Discard (TOD) scheduling protocol is utilized to decide which slave gets the network access at each triggered instant. A control algorithm with the event-triggered mechanism is proposed to ensure the master–slaves synchronization. Furthermore, the closed-loop system's stability criterion associated with the controller gains, the varying time delays' bounds, and the maximum transmission interval is established on the basis of the Lyapunov–Krasovskii analysis. Finally, the presented algorithm's performance is demonstrated by the simulation and experiment results.

This paper designs a continuous-time algorithm with event-triggered communication (ETC) for solving a class of distributed convex optimization problems with a metric subregularity condition. First, we develop an event-triggered continuous-time optimization algorithm to overcome the bandwidth limitation of multi-agent systems. Besides, with the aid of Lyapunov theory, we prove that the distributed event-triggered algorithm converges to the optimum set with an exact linear convergence rate, without the strongly convex condition. Moreover, we provide the discrete version of the continuous-time algorithm and show its exact linear convergence rate. Finally, we give a comparison example to validate the effectiveness of the designed algorithm in communication resource saving.

The problem of fixed-time adaptive event-triggered fault-tolerant control (FTC) is investigated for a class of nonlinear systems with actuator failures in this paper. Firstly, by utilizing back-stepping algorithm and the fixed-time stable criterion, a novel fixed-time adaptive fault-tolerant controller and parameter updated laws in forms of nonlinear differential equations are developed to counteract actuator faults and parameter uncertainties in fixed time. Then, the event-triggered mechanism based on the relative threshold method is applied to the proposed control scheme to save network resources. Furthermore, by the Lyapunov stability theory, it can be proven that all the closed-loop signals of system remain bounded, and the tracking error converges into a small neighborhood of the origin within fixed time interval. Finally, the simulation examples are shown to verify the feasibility and efficiency of the presented strategy.

This work presents a resilient distributed model predictive control (MPC) method for linear parameter varying (LPV) systems with state delays and attacks in communication networks. Coordinations are required for distributed MPC (DMPC) to achieve the global performance of centralized MPC (CMPC). However, control performance can be severely degraded by unreliable communication networks, for example, with denial of service (DoS) attacks. A resilient control framework is derived to address the unreliable communications in DMPC. A global system is divided into subsystems for the distributed control purpose. To deal with the model uncertainties and state delays, a “min-max” DMPC algorithm is presented with a buffer to ensure resilience against DoS attacks. A quantization scheme is introduced to quantize the control information exchanged between subsystems. An iterative interaction scheme is proposed to exchange feedback control laws among subsystems. The stability of the closed-loop system under the proposed algorithm is ensured by using a Lyapunov function method. The effectiveness of the proposed DMPC is demonstrated through two simulation examples.

In this paper, a dynamic event-triggered control problem is discussed for 2-D continuous systems by the Roesser model. In order to reduce communication frequency and avoid dependence on global information, a dynamic event-triggered mechanism is constructed, which is more flexible than some existing event-triggered schemes with fixed event-triggered thresholds. Utilizing the dynamic event-triggered mechanism, a state feedback controller is designed. By constructing a 2-D Lyapunov function, sufficient conditions expressed in terms of linear matrix inequalities (LMIs) are firstly established such that the 2-D system is asymptotically stable with a disturbance attenuation performance. It is also proved that the Zeno phenomenon is excluded. Finally, two examples are provided to illustrate the effectiveness of the proposed method.

The paper studies the restabilization problem of Boolean control networks (BCNs) under the function perturbation. First, an important concept-absorbable attractor is proposed for BCNs. Then, by using this concept, a necessary and sufficient restabilizability criterion is established. This criterion can be used to check whether the perturbed BCN can be restabilized to its original state by modifying the minimum number of parameters in the old controller. Finally, a constructive fine-tuning method is given to modify the old controller. Compared with the existing results, which can only solve the problem of single column function perturbation, our results are more powerful since they are applicable not only to the single column function perturbation problem but also to the case of multiple columns. Finally, two examples are employed to show the effectiveness of our results.

The study focuses on the event-triggered dynamic output feedback control for a type of switched linear neutral systems under time-varying delays and frequent asynchronism. Distinct from the existing literatures about asynchronous switching, which restricts the minimum dwell time, frequent switching is allowed to occur within each inter-event interval by reason of average dwell time method. Then, concentrated on switched neutral time-delay system, a novel sufficient condition is established under which proposed event-triggered control scheme guarantees its the global uniform exponential stability by using the controller-mode-dependent Lyapunov functional together with dynamic output feedback controller. Subsequently, the sufficient criteria are deduced for co-designing the dynamic output feedback controller and mode-dependent event-triggered mechanism. Additionally, it is proved that a positive minimum threshold on the inter-event intervals exists, which eliminates Zeno phenomenon. In the end, a numerical simulation indicates the efficacy of the acquired results.

An improved integral backstepping sliding mode control (IIBSMC) strategy is proposed to address the problems of long regulation time and poor disturbance resistance of integral backstepping control (IBC) for quadrotor aircraft. The IIBSMC method first introduces the integral term into the virtual variable on the basis of IBC, which makes the system respond faster, overshoot smaller and anti-interference performance stronger. After that, combined with sliding mode control, the system is further processed to improve the control performance of the system. Finally, the quadrotor is controlled to achieve fixed-point hovering and trajectory tracking, and the rotation and translation performance of the aircraft and the stability under external interference are improved. When the quadrotor aircraft is subjected to instantaneous interference, constant interference, sinusoidal interference, white noise interference, and complex interference, the simulation experiments of IBC, improved integral backstepping control (IIBC), integral backstepping sliding mode control (IBSMC), and IIBSMC are compared. It can be obviously found that the IIBSMC method has smaller system overshoot, faster recovery of the original equilibrium position, shorter adjustment time, and smaller error. When using the IIBSMC method to design the controller, the stability of the controller is theoretically proved by backstepping recursion. Finally, the simulation results show that the designed controller can better achieve fixed-point hovering and trajectory tracking control well.

The dielectric elastomer actuator (DEA) is widely used in the field of soft robots due to its large deformation, light weight, fast response, and high-energy conversion efficiency. The high-precision control of the DEA is the precondition for soft robots to perform complicated tasks. In early studies, researchers usually employed integer order modeling and control methods to build the dynamic model of the DEA and to achieve its tracking control. However, these methods are not good at handling the complicated memory property of the DEA. In addition, the number of required parameters in integer order models and control methods is enormous, which hinders their practical applications. To solve these problems, the fractional order modeling method and fractional order internal model control method of the DEA are proposed in this paper. Firstly, a fractional order transfer function (FOTF) model of the DEA is built to depict its complicated memory property. Then, to achieve the computer control, an integer order approximation model (IOAM) of the FOTF model is built by using the Oustaloup filter. Considering that the order of the IOAM is too high, a reduced integer order approximation model is established by using the square root balance truncation algorithm to facilitate the system controller design. Next, a fractional order internal model controller is designed. Finally, tracking control experiments are exerted to demonstrate the effectiveness of the proposed method. Since the root-mean-square errors of all experimental results are less than 2%, the proposed modeling method and control method are superior from the perspective of the practical application.