Event-triggered Sampling Mechanism Research Articles

Model Predictive Control With Guaranteed Feasibility of Inequality Path Constraints.

This article concerns nonlinear model predictive control (MPC) with guaranteed feasibility of inequality path constraints (PCs). For MPC with PCs, the existing methods, such as direct multiple shooting, cannot guarantee feasibility of PCs because the PCs are enforced at finitely many time points only. Therefore, this article presents a novel MPC framework that is capable of not only achieving stability control but also guaranteeing feasibility of PCs during the rolling optimization stages of MPC. Under the above MPC framework, an algorithm is first proposed by applying the semi-infinite programming technique to the rolling optimization of MPC. However, it takes heavy computational time to achieve guaranteed feasibility of PCs. Therefore, to guarantee feasibility of PCs meanwhile effectively reducing the computation burden of the closed-loop system, an event-triggered sampling mechanism is constructed in the above path-constrained MPC algorithm. Moreover, sufficient conditions are given for asymptotic convergence of the closed-loop systems. Finally, the effectiveness of the proposed results is illustrated via a cart-damper-spring system.

Tracking Control of Unicycle Mobile Robots With Event-Triggered and Self-Triggered Feedback

This paper studies the tracking control problem for unicycle mobile robots with event-triggered and self-triggered feedback. Based on a modified dynamic feedback linearization technique and a refined stability analysis, we first propose a new class of saturated sampled-data controllers for unicycle mobile robots of which the state is subject to sampling (measurement) errors. It is guaranteed that the generated control inputs are restricted to within desired ranges, and the unicycle trajectory practically converges towards a time-varying trajectory as long as the sampling errors satisfy a saturated sector bound condition with a nonnegative offset. The proposed robust controller gives rise to a novel event-triggered sampling mechanism with a saturated threshold signal, which adjusts the sampling errors online to steer the tracking error to a desired neighborhood of the origin and guarantees a positive lower bound for the intersampling intervals. As a special case, by designing appropriately the controller and the event-triggered sampling mechanism, asymptotic tracking is achievable. New self-triggered and periodic sampling mechanisms are also developed as natural extensions of the ev

Event-triggered consensus control for singular multi-agent systems based on observers

This paper is devoted to the problem of event-triggered consensus for a class of general linear singular multi-agent systems with undirected topology. Considering that the system states are not measurable, state observers are designed first, and then a new observer-based event-triggered sampling mechanism is proposed, which naturally avoids Zeno behavior. Furthermore, a distributed event-triggered consensus protocol is designed. By employing the Lyapunov-Krasovskii functional method and model transformation approach, sufficient conditions are obtained such that the consensus of the singular multi-agent systems can be achieved, while the explicit dynamic expression of the consensus function is also given. Finally, a numerical example is included to illustrate the effectiveness of the proposed results.

Event-triggered control with waiting time based on state observer for switched linear systems

This paper concentrates on the state observer–based event-triggered control problem for a class of switched linear systems with external disturbance and transmission delay. It is assumed that the controller can only access the transmitted information of the state observer at each delayed event-triggered instant with a waiting time. First, by adopting the multiple Lyapunov–Krasovskii functional method, some sufficient conditions are derived for the establishment of the state observer, the input-to-state stability (ISS) and the globally uniformly exponential stability (GUES) of the switched linear systems under adjacent mode-dependent average dwell time (AMDADT) scheme. Then, we propose a state observer-based event-triggered sampling mechanism with waiting time and design an observer-based state feedback controller for the considered switched systems. Under the proposed event-triggered mechanism, the Zeno behavior can be easily excluded in all sampling processes. Finally, a numerical example is included to validate the proposed theory.

ESO-based event-triggered attitude control of spacecraft with unknown actuator faults

An event-triggered control strategy based on extended state observer (ESO) is proposed for the attitude tracking problem of small plug-and-play spacecraft with uncertain inertia parameters, external disturbances, and actuator faults. A simplified controller is developed based on the angular velocity and the general disturbances estimated by the provided ESO using the information of the system inputs and the angular velocities. In the designed event-triggered sampling mechanism, a state-dependent event-triggered strategy determines the triggering instant of the controller to reduce the frequency of information transmission between the controller and the actuator. In comparison with the previous literature, this paper considers uncertain inertia parameters, external disturbances, and actuator faults as general disturbances estimated by ESO, especially for the actuator faults. The inputs of ESO are the error of the angular velocities, which can simplify the controller design. Moreover, the designed ESO can effectively attenuate the influence of measured noises generated by the gyroscopes. The proposed event-triggered policy balances the performance of event-triggering and the control stability performance, which reduces the final state convergence regions without increasing more triggering times compared to existing studies. Furthermore, the investigated policy achieves Zeno-free triggering. Numerical simulations verify theoretical results.

Robust Event-Triggered Control of Nonlinear Systems Under a Global Sector-Bound Condition

This paper studies an event-triggered control problem for nonlinear systems subject to both external disturbances and dynamic uncertainties. It is assumed that the system satisfies a global sector-bound condition. To avoid infinitely fast sampling, a novel event-triggered sampling mechanism is proposed, which uses not only the measured system state but also an estimation of the influence of the disturbances. With the proposed design, the intersampling intervals can be lower bounded by a positive constant, and it is independent of both external disturbances and dynamic uncertainties. Moreover, the closed-loop event-triggered system is proved to be input-to-state stable with respect to the external disturbances. Advanced small-gain techniques are used for the stability analysis of the closed-loop system.

Multi-spacecraft attitude synchronization based on performance adjustable event-triggered control

This paper is devoted to solving the multi-spacecraft attitude synchronization problem via performance adjustable event-triggered control in the presence of external disturbances and model uncertainties. In the proposed control policy, the inter-spacecraft information interaction is determined by an event-triggered sampling mechanism, and the influences of external disturbances and model uncertainties are counteracted by an adaptive estimation. This sampling method does not only reduce communication resource consumption but also provides a trade-off between resource savings and synchronization accuracy. Moreover, the corresponding performance-adjustable triggering function can achieve Zeno-free triggering. According to the comparison of some numerical simulation results, this paper shows that the provided control policy is effective and superior.

Adaptive Resilient Event-Triggered Control Design of Autonomous Vehicles With an Iterative Single Critic Learning Framework

This article investigates the adaptive resilient event-triggered control for rear-wheel-drive autonomous (RWDA) vehicles based on an iterative single critic learning framework, which can effectively balance the frequency/changes in adjusting the vehicle's control during the running process. According to the kinematic equation of RWDA vehicles and the desired trajectory, the tracking error system during the autonomous driving process is first built, where the denial-of-service (DoS) attacking signals are injected into the networked communication and transmission. Combining the event-triggered sampling mechanism and iterative single critic learning framework, a new event-triggered condition is developed for the adaptive resilient control algorithm, and the novel utility function design is considered for driving the autonomous vehicle, where the control input can be guaranteed into an applicable saturated bound. Finally, we apply the new adaptive resilient control scheme to a case of driving the RWDA vehicles, and the simulation results illustrate the effectiveness and practicality successfully.

Event-triggered distributed filtering for Markov jump systems over sensor networks

This article deals with the distributed filtering problem for a class of discrete-time Markov jump systems over sensor networks. First, in the distributed filtering network, each local filter simultaneously fuses the estimation and measurement from itself and neighboring nodes to achieve the system state estimation. And each sensor intelligent node is embedded with an event-triggered sampling mechanism, which can reduce the computation load or saving limited network bandwidth. Then, we use Bernoulli stochastic variables to describe whether the filtering network can successfully receive the system jump modes. Next, based on the Lyapunov stability theory, we design a distributed filter dependent on partial system modes, which has the exponential stability in mean square and [Formula: see text] performance. Finally, all desired estimator parameters can be obtained by solving a set of linear matrix inequalities. Moreover, two numerical examples are given to illustrate the effectiveness of the distributed [Formula: see text] filtering design approach.

Finite-Time Stabilization of Switched Systems with Time-Varying Delay

This paper studies the problem of finite-time stabilization of a class of switched linear time-varying delay systems. An event-triggered sampling mechanism and an event-triggered state feedback control are proposed. Based on Lyapunov-like function method, linear matrix inequality technique and averaged dwell time method, sufficient conditions for switched delay systems under event-triggered state feedback control are given to ensure the finite-time stabilization of the switched delay systems. Finally, a numerical example is given to verify the validity of the proposed results.

Secure Control of Networked Switched Systems with Random DoS Attacks via Event-triggered Approach

This paper considers security control of networked switched systems in which the denial-of-service attacks may happen when the output information is transmitted from the sensor to the controller. Besides, it is assumed that the denial-of-service obeys Bernoulli distribution. First, to reduce the communication burden and retaining a satisfactory performance, an event-triggered sampling mechanism is adopted. And then, security control of the switched systems is analyzed by designing an output-feedback controller and a switching signal based on the average dwell time method. It is shown that the state trajectory can be driven onto a certain bound despite the presence of the random denial-of-service attacks. Finally, a numerical example is given to demonstrate the effectiveness of the proposed method.

Interval observer-based event-triggered control for switched linear systems

This paper studies the interval observer-based event-triggered controller design for switched systems involving additive disturbance and measurement noise. We first extend the definition of asymptotic interval observers for general non-switched systems into switched ones. Then, by giving the bound of the disturbance and the measurement noise and adopting the multiple Lyapunov function method, some sufficient conditions are derived and applied to build the interval observer, which supply certain information at any instant: an upper bound and a lower bound are provided for each component of the states. Next, we propose an event-triggered sampling mechanism and design an interval observer-based state feedback controller for the considered switched systems. Finally, we afford two examples to illustrate the validity of the derived results.

Observer-based event-triggered H∞ control for asynchronous switched delay systems

In this paper, the [Formula: see text] performance of observer-based asynchronous linear switched delay systems with an event-triggered sampling scheme is considered. Firstly, owing to the system state cannot be measured completely in practice, a state feedback observer is used to reconstruct the system state. Next, we design an event-triggered sampling mechanism, under which the sample of the system only occur when the error exceeds a predetermined threshold, so it will reduce economic losses. Then, considering the asynchronous switching between the subsystems and the controllers, some sufficient conditions are proposed by using merging switching signal method and multiple Lyapunov function method to ensure the [Formula: see text] performance of the asynchronous closed-loop system. Finally, a numerical example is given to illustrate the validity of the results.

Event-triggered control for linear continuous switched singular systems

Event-triggered control is an effective control scheme, which can reduce the number of samplings without affecting a desirable system performance. The state-based and observer-based state feedback control are studied for linear switched singular systems in continuous-time case. Firstly, we provide an improved event-triggered sampling mechanism. Next, a set of co-design methods are presented, namely, the construction of switching laws, event-triggered scheme and the choice of controller parameters are jointly discussed. Furthermore, the stability conditions are achieved in terms of global E-uniform boundedness providing that the average dwell time is satisfied for considered systems. In our paper, the improved event-triggered mechanism is adopted and obtained results have less conservatism than existing results. Finally, we illustrate the feasibility via numerical examples.

A novel event-triggered communication strategy for second-order multiagent systems

This paper concentrates on the design of an event-triggered communication strategy for secondary multi-agent systems. Many existing results in this field usually require centralized information depending on the Laplacian matrices. In a real application, however, such the constraint is conservative. To address it, this paper proposes an event-triggered sampling mechanism for interagent communication with updated thresholds. Accordingly, consensus protocols with adaptive coupling control gains are proposed for both a fixed topology and switching topologies. It is proven that the proposed method guarantees the leader-following consensus for second-order multiagent systems with an arbitrarily connected topology and even with jointly connected switching topologies. The effectiveness of the proposed scheme is verified by simulation examples.

Real-Time H∞ Control of Networked Inverted Pendulum Visual Servo Systems.

Aiming at the challenges of networked visual servo control systems, which rarely consider network communication duration and image processing computational cost simultaneously, we here propose a novel platform for networked inverted pendulum visual servo control using H∞ analysis. Unlike most of the existing methods that usually ignore computational costs involved in measuring, actuating, and controlling, we design a novel event-triggered sampling mechanism that applies a new closed-loop strategy to dealing with networked inverted pendulum visual servo systems of multiple time-varying delays and computational errors. Using the Lyapunov stability theory, we prove that the proposed system can achieve stability whilst compromising image-induced computational and network-induced delays and system performance. In the meantime, we use H∞ disturbance attenuation level γ for evaluating the computational errors, whereas the corresponding H∞ controller is implemented. Finally, simulation analysis and experimental results demonstrate the proposed system performance in reducing computational errors whilst maintaining system efficiency and robustness.

Differentially Private Event-Triggered Sampling

This paper describes a differentially private event-triggered sampling mechanism to select measurement samples from a data sequence whose dynamics can be modelled by a stochastic linear system. The mechanism produces subsequences that can be used to reestimate the original sequence relatively accurately and the differential privacy constraint guarantees that these subsequences are insensitive to certain variations in the input sequence. The subsampling process can be motivated by the presence of communication bandwidth constraints, but also provides an additional tool to explore achievable privacy-utility tradeoffs in privacy-preserving signal processing and control. Event-triggered sampling can offer benefits over periodic subsampling by attempting to select the most useful samples, but the fact that it leaks information when no sampling occurs must be carefully taken into account to meet the differential privacy requirement. We propose a design using a stochastic sampling threshold, leveraging the "sparse vector technique" from differential privacy to incur a privacy loss only when samples are actually released. This design includes a suboptimal but tractable recursive finite-dimensional estimator that can also be used to re-estimate the original sequence from the differentially private noisy subsequence.

Stabilization of Switched Linear Neutral Systems: An Event-Triggered Sampling Control Scheme

Event-triggered control is an effective control strategy, capable of reducing the amount of communications and retaining a satisfactory closed-loop performance. In this paper, we aim at proposing an event-triggered sampling mechanism and studying observer-based output feedback control for switched linear neutral systems with mixed time-varying delays. Different from the conventional event-triggered control strategies, our proposed one transmits not only the state but also the switching information to the controller, which is advantageous in applications where the measured outputs and the switching information have to be transmitted over a communication network. Moreover, asynchronous switchings may be caused between the subsystems and their matched subcontrollers under the proposed sampling mechanism, which increases difficulties in analyzing stability. We develop a sufficient condition, under which the proposed control scheme guarantees globally the exponential stability of the closed-loop system meanwhile taking into account asynchronous switchings. Finally, an illustrative example is given to show the effectiveness of the proposed method.

Improved event‐triggered control for a class of continuous‐time switched linear systems

Both state-based and observer-based output feedback event-triggered controls for continuous-time switched linear systems are studied. An improved event-triggered sampling mechanism is adopted in feedback control, under which Zeno behaviour can be easily excluded in sampling process. Meanwhile, it is shown that the closed-loop switched system is stable in the sense of global uniform boundedness satisfying an average dwell time condition. A numerical example is finally given to verify the developed results.

Event-triggered sampling and fault-tolerant control co-design based on fault diagnosis observer

A co-design scheme of event-triggered sampling mechanism and active fault tolerant control (FTC) is developed. Firstly, a fault diagnosis observer is designed to estimate both the fault and the state simultaneously by using the event-triggered sampled output. Some H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> constraints between the estimation errors and the event-triggered sampling mechanism are established to ensure the estimation accuracy. Then, based on the constraints and the obtained fault information, an event-triggered detector and a static fault tolerant controller are co-designed to guarantee the stability of the faulty system and to reduce the sensor communication cost. Furthermore, the problem of the event detector and dynamic FTC co-design is also investigated. Simulation results of an unstable batch reactor are finally provided to illustrate the effectiveness of the proposed method.