Asynchronous Controller Research Articles

Asynchronous Mean Stabilization of Positive Jump Systems With Piecewise-Homogeneous Markov Chain

In this brief, the mean stabilization of positive Markov jump systems (PMJSs) with piecewise-homogeneous Markov chain with two switching signals simultaneously is considered. Different from the existing results, asynchronous state feedback controllers are considered to achieve the control objective. Based on the hidden Markov model, the closed-loop systems are modeled as hidden Markov jump systems (HMJSs) with piecewise-homogeneous Markov chain. The definitions of positivity and mean stabilization are introduced for the considered system. Some sufficient conditions are derived to ensure that the HMJSs with piecewise-homogeneous Markov chain are positive and mean stable when the Markov chain follows a conditional probability distribution and Bernoulli distribution, respectively. Simulation results are described to demonstrate the effectiveness of our approach.

Robust Asynchronous H∞ Observer-Based Control Design for Discrete-Time Switched Singular Systems with Time-Varying Delay and Sensor Saturation: An Average Dwell Time Approach

This work discuss the robust stabilization problem for discrete-time switched singular systems with simultaneous presence of time-varying delay and sensor nonlinearity. To this end, an observer-based controller was synthesized that works under asynchronous switching signals. Investigating the average dwell time approach and using a Lyapunov–Krasovskii functional with triple sum terms, sufficient conditions were derived for achieving the existence of such asynchronous controller and guaranteeing the resulting closed-loop system to be exponentially admissible with H∞ performance level. Subsequently, the effectiveness of the proposed control scheme was verified through two numerical examples.

A novel event-triggered asynchronous H∞ control for T-S fuzzy Markov jump systems under hidden Markov switching topologies

This paper investigates the network-based H∞ control problem for Takagi-Sugeno fuzzy Markov jump systems with communication delays. Firstly, we propose a novel mode-dependent event-triggered communication scheme (ETCS) based on aperiodically sampled data, which largely reduce the data transmission. Secondly, to obtain a more applicable result, an asynchronous controller based on a hidden Markov model is designed for the first time to stabilize the fuzzy Markov jump systems with general transition rates. Thirdly, a less restrictive Lyapunov-Krasovskii functional, which is discontinuous and only required to be positive definite at endpoints of each subinterval of the holding intervals, is newly introduced for event-triggered asynchronous control issue. Based on the above methods, sufficient conditions with less conservatism are obtained to ensure the stochastic stability of the resulting closed-loop systems with a prescribed H∞ performance. A co-design method of the desired controller and ETCS is then presented. Finally, truck-trailer model and mass-spring-damper model are provided to demonstrate the effectiveness and practicability of the developed results.

A multiple convex Lyapunov function for asynchronous control of discrete-time switched systems

In this paper, the problem of asynchronous control for a class of discrete-time switched systems is investigated under mode-dependent integrated dwell time (MDIDT) switching. By constructing a time-dependent convex function, a multiple convex Lyapunov function (MCLF) is firstly proposed for the asynchronous control of the switched systems. Under the MDIDT switching strategy, the matching interval is divided reasonably, and the convex function combination is constructed on the partitioned interval. Under asynchronous switching, the Lyapunov function is continuous when the subsystem mode is switched, but discrete when the controller mode is changed. Then, the increase of the Lyapunov function in the mismatched interval will be offset by the attenuation in the matched interval. In light of these merits, the stability results of the system are deduced, and the asynchronous controller is devised to guarantee the globally uniformly exponentially stability of the closed-loop system. Comparing with the traditional asynchronous control methods, the proposed method has less conservative results and larger stability regions. Finally, a numerical example and an application example are demonstrated to verify the validity and superiority of the asynchronous control scheme.

Reusable Delay Path Synthesis for Lightening Asynchronous Pipeline Controller

In this work, we address the synthesis problem of two-phase bundled-data asynchronous pipeline controllers, in which the insertion of buffers is essential for guaranteeing the correct handshaking operation on every pipeline stage at the expense of considerable area increase. To lighten the pipeline controllers, we introduce a new logic synthesis concept called delay path sharing and reusing , by which we can significantly reduce the amount of the costly delay buffers. Precisely, first, we propose a technique of synthesizing an asynchronous pipeline controller in a way to share delay buffers among setup timing paths on pipeline stages for minimally allocating total delay buffers. In addition, we devise an area-efficient delay circuit structure called delay path unit (DPU) by extending the proposed delay path sharing concept and propose an in-depth synthesis flow of an asynchronous pipeline controller using DPUs. Through experiments with benchmark circuits using a 45-nm cell library, it is shown that our techniques of synthesizing asynchronous pipeline controllers are able to reduce the controller area by up to 46.3%–59.4% and the leakage power by up to 33.0%–49.0% on average while retaining the same level of performance.

Admissibility analysis and passive output feedback control for one-sided Lipschitz nonlinear singular Markovian jump systems with uncertainties

The paper investigates admissibility analysis, the existence and uniqueness (EU) of solutions and robustly passive asynchronous static output feedback (SOF) control for one-sided Lipschitz (OSL) nonlinear singular Markovian jump systems (SMJSs) with uncertainties. Sufficient conditions are derived to guarantee that OSL nonlinear SMJSs are regular, impulse-free, stochastically stable and have a unique solution with passive performance by using implicit function theorem. With these conditions, the design of robust asynchronous SOF controller is presented in form of linear matrix inequality (LMI) constraints. Finally, an example is given to evaluate the operation of our proposed methods.

Observer-Based Distributed Mean-Square Consensus Design for Leader-Following Multiagent Markov Jump Systems.

This paper addresses the mean-square leader-follower consensus problem for the multiagent Markov jump linear systems. The leader has the general linear dynamics while the followers are subject to parameter changes modeled by Markov jump. By using the output measurement of the leader, two types of observers, namely, the common observer and the distributed adaptive observer, are first constructed together to estimate the leader state. Then based on the estimated state and the follower self information, two kinds of controllers, namely, the synchronous controller and the asynchronous controller, are designed to achieve the mean-square leader-follower consensus. Finally, the simulation results are given to illustrate the feasibility and effectiveness of the proposed approaches.

Asynchronous [formula omitted] control for hidden singular Markov jump systems with incomplete transition probabilities via state decomposition approach

This paper addresses the asynchronous H∞ control problem for hidden singular Markov jump systems (HSMJSs) with incomplete transition probabilities. By employing the state decomposition approach, a novel augmented Lyapunov-Krasovkii functional (LKF) with the components of state vectors is designed to reduce the redundant decision variables. Meanwhile, a parameter-dependent reciprocally convex matrix inequality (PDRCMI) is introduced to decrease conservatism. To handle the non-synchronization phenomenon of the system mode and the controller mode, an asynchronous state feedback controller based on hidden Markov model (HMM) is developed. In addition, the incomplete transition probabilities are considered so that a more practical potential strategy is addressed. Finally, numerical examples are provided to illustrate the superiority and practicability of the presented results.

Neural network based asynchronous synchronization for fuzzy hidden Markov jump complex dynamical networks

This paper investigates the drive-response synchronization problem of Takagi–Sugeno fuzzy hidden Markov jump complex dynamical networks. More precisely, a novel asynchronous synchronization control strategy is developed for coping with mismatched hidden jumping modes. Furthermore, the neural network is adopted with online learning laws for unknown function approximation. By taking advantage of Lyapunov method, sufficient conditions are established to ensure mean-square synchronization performance with disturbances. Based on the synchronization criterion, asynchronous controller gains are designed in terms of linear matrix inequalities. An illustrative example is finally given to validate the effectiveness of the proposed synchronization techniques.

Robust Sampled-Data Control for Switched Complex Dynamical Networks With Actuators Saturation.

In this article, an aperiodic sampled-data control problem is investigated for polytopic uncertain switched complex dynamical networks subject to actuator saturation. Due to the constraint on the upper bound of the sampling interval being no greater than the dwell time, the issue concerning the asynchronization between the sampled-data controller mode and the system mode is hence considered to be caused by subsystems that may switch in a sampling interval. By considering the sampling interval without switching and the sampling interval with switching, the parameters-dependent loop-based Lyapunov functionals are constructed, respectively. With the help of the constructed functional, mean-square exponential stability criteria for the error polytopic uncertain switched complex dynamical networks are presented under the definition of average dwell time. Furthermore, based on the stability criteria, the asynchronous aperiodic sampled-data controller is designed for polytopic uncertain switched complex dynamical networks subject to actuator saturation. The polytopic uncertain switched complex dynamical networks can be guaranteed to exponentially synchronize with the target node based on the proposed stability conditions and aperiodic sampled-data controller design method. Finally, by transforming the proposed theoretical conditions into the LMI-based objective optimization problem, the domain of attraction of polytopic uncertain switched complex dynamical networks is estimated. An example based on switched Chua's circuit is applied to verify the effectiveness of the proposed method.

Asynchronous quadratic control for constrained hidden markov jump linear systems with incomplete MTPM and MOCPM

AbstractThis paper investigates the quadratic optimal control problem for constrained Markov jump linear systems with incomplete mode transition probability matrix (MTPM). Considering original system mode is not accessible, observed mode is utilized for asynchronous controller design where mode observation conditional probability matrix (MOCPM), which characterizes the emission between original modes and observed modes is assumed to be partially known. An LMI optimization problem is formulated for such constrained hidden Markov jump linear systems with incomplete MTPM and MOCPM. Based on this, a feasible state-feedback controller can be designed with the application of free-connection weighting matrix method. The desired controller, dependent on observed mode, is an asynchronous one which can minimize the upper bound of quadratic cost and satisfy restrictions on system states and control variables. Furthermore, clustering observation where observed modes recast into several clusters, is explored for simplifying the computational complexity. Numerical examples are provided to illustrate the validity.

Asynchronous quantized control of Markovian switching Lur’e systems with event-triggered strategy

This work is devoted to investigating the asynchronous quantized control of discrete-time Markovian switching Lur’e systems with an event-triggered mechanism. To model the asynchronous controller and the quantization effects, the hidden Markov model is employed. For reducing the burden of communication bandwidth, an event-triggered mechanism is adopted. By choosing the proper stochastic Lyapunov functional, sufficient conditions are derived. Finally, a practical example is given to illustrate the effectiveness and efficiency of the proposed method.

Dynamic event-based dissipative asynchronous control for T–S fuzzy singular Markov jump LPV systems against deception attacks

In this article, the issue of dissipative asynchronous control for continuous-time T–S fuzzy singular Markov jump linear parameter-varying systems against dual deception attacks under the dynamic event-triggered transmission protocol (DETP) is investigated. Firstly, the DETP is offered to further abate the channel congestion caused by the limited bandwidth. Meanwhile, the mutually independent random variables subject to Bernoulli distribution are utilized to model the dual deception attacks, which can destroy the integrity of the considered system to some degree. Besides, since the controller can not accurately receive the system information, a hidden Markov model is established to depict the asynchronous phenomenon. Specifically, in the light of the parameter-dependent Lyapunov functional, the stochastic admissible criterion of the closed-loop system with certain dissipative performance and uncertain transition rates is obtained. Ulteriorly, based on the parameter-dependent linear matrix inequalities, a cooperative design technique of asynchronous controller and the weighting matrix of the DETP is proposed. Finally, two examples of chaotic systems and electric truck-trailer systems under the DETP are given to illustrate the feasibility of the proposed method.

Energy-efficient inverter circuit for the low-voltage asynchronous driver controller with autonomous power supply

The design of the energy-efficient inverter circuit for the asynchronous frequency-controlled three-phase electric driver with autonomous low-voltage DC power supply. The components analysis of the electric drive, the main components selection approach: microcontroller, three-phase driver and power transistors. R&D prototype of the energy-efficient inverter circuit was created, characterized by an average consumption current reduced by 5%. Reducing energy losses is achieved by reducing dynamic losses in the power circuits of a low-voltage inverter and using several circuit solutions.

Novel Asynchronous Activation of the Bio-Inspired Adaptive Tuning in the Speed Controller: Study Case in DC Motors

The fusion of bio-inspired algorithms into online controller tuning (adaptive controller tuning) is one of the main topics in Intelligent Control. One crucial issue is to reduce the times that the tuning process performs over time. In this work, a novel Asynchronous Adaptive Controller Tuning (AACT) approach is proposed to reduce the number of tuning process activations, and hence, this promotes resource savings in the overall computational cost for the tuning process. In this approach, an event function is designed to determine the control parameter update where the use of identification and predictive stages set the current control parameters. Furthermore, an elitist initialization in the differential evolution algorithm is also incorporated for solving the optimization problems at each stage. The speed regulation of the DC motor under disturbances is the study case in the ACCT approach. Comparative results with state-of-the-art bio-inspired algorithms in control tuning reveal in the AACT approach that the elitist initialization in differential evolution notably benefits the controller performance. Moreover, the comparative results with the Synchronous Adaptive Controller Tuning (SACT) approach show that the proposal reduces 61% the tuning process computation frequency with a similar speed regulation performance when disturbances appear.

Dissipative Control for Fuzzy Singular Markov Jump Systems With State-Dependent Noise and Asynchronous Modes

In this paper, the issue of dissipative control for a class of discrete-time T-S fuzzy singular Markov jump systems with state-dependent noise and asynchronous modes is investigated. The hidden Markov model (HMM) is introduced to observe the asynchronous phenomenon between the original system modes and the controller modes. Sufficient conditions are established in the form of strict LMIs to guarantee that the closed-loop system is stochastically admissible and strictly $(Q, S, R)-\beta $ dissipative. An asynchronous output feedback controller is successfully proposed, which is more general than synchronous and mode-independent ones. Finally, the effectiveness and validity of the obtained results are illustrated by a numerical example.

A Fast Droop-Recovery Event-Driven Digital LDO With Adaptive Linear/Binary Two-Step Search for Voltage Regulation in Advanced Memory

This letter presents an event-driven digital low-dropout regulator (DLDO) with an adaptive linear/binary two-step search achieving a fast transient response. A two-dimensional (2-D) circular shifting register (CSR) offers an adaptive linear-search regulation. When a large voltage droop occurs, the CSR activates a fast-tracking mode that provides immediate recovery from the droop. Once the linear search by the CSR is completed, a subrange successive-approximation register (Sub-SAR) conducts the binary-search regulation. The full-scale current range of the Sub-SAR is adaptively scaled by referencing the CSR, which reduces the number of searching steps and improves undershoot or overshoot caused by the binary-search operation. Ring amplifier based 1.5b continuous-time (CT) comparators and the asynchronous controllers realize the event-driven operation that breaks a tradeoff between transient response and sampling clock frequency. The proposed DLDO was fabricated in a 40 nm CMOS process. The DLDO can operate in an input voltage V IN range from 0.6 to 1.2 V. When a load current step of 104.2 mA/1 ns was applied at a V IN of 1.0 V, a droop-recovery time and a settling time were measured as 6 and 15 ns, respectively.

Local Stabilization of Continuous-Time T–S Fuzzy Systems With Partly Measurable Premise Variables and Time-Varying Delay

This paper investigates the local stabilization problem for T–S fuzzy systems with partly measurable premise variables and time-varying delay. First, by using the measurable premise variables, a novel output feedback controller scheme is proposed. Second, via restricting the reachable set into an ellipsoid set, which is bounded by the objective region, the system state can be contained into a prespecified area so that the purpose of local stabilization can be fulfilled. Furthermore, because of network delay, there is a deviation between the membership function of the system and those of the controller. By exploring the information of the deviation, the stabilization condition can be further relaxed. Compared with the existing results, the new asynchronous controller strategy can simultaneously make full use of the information of the measurable premise variables and the aforementioned deviation for a less conservative result. Finally, an illustrative example is given to show the applicability of the presented approach.

Reachable set synthesis for discrete-time Markovian jump systems with time-varying delay by partially asynchronous control

Abstract The problem of reachable set synthesis for discrete-time Markovian jump system-s(MJSs) with time-varying delay is researched. Different from the traditional controller, a kind of partially asynchronous controller is proposed. The normal system mode and the asynchronous mode are fully considered in the desired control law including delay state and delay-free state that happen asynchronously. Moreover, Bernoulli random variables are applied to represent the probability distribution of above two kinds of states. On these foundations, by employing Lyapunov theory and linear matrix inequalities(LMIs), a sufficient condition of the reachable set synthesis for MJSs under partially asynchronous control is given. Finally, a numerical example is provided to show the effectiveness of the proposed methods.

Finite‐time dissipative control for time‐delay Markov jump systems with conic‐type non‐linearities under guaranteed cost controller and quantiser

For a class of conic-type non-linear time-delay Markov jump systems, the asynchronous dissipative output feedback controller based on the guaranteed cost control and quantiser is designed in this study. In real applications, the system and the controller modes are always non-synchronous, so we introduce the hidden Markov model to solve this problem. Furthermore, we define three novel auxiliary variables and use quantisers to accomplish the output feedback controller design. Then, the finite-time boundedness and strict dissipativity of the closed-loop systems are guaranteed by sufficient conditions, and the controller also meets the guaranteed cost-control performance. By solving a set of linear matrix inequalities, we get the controller gains, the guaranteed cost control performance index J*, and the dissipative performance index α. Finally, the correctness and feasibility of this designed approach are demonstrated by a given example.