Consensus Error Research Articles

Accuracy of the Standard GlucoNavii Mentor in Blood Glucose Monitoring According to International Organization for Standardization 15197:2013 Criteria

This study was performed to assess the system accuracy of the blood glucose monitoring system SD GlucoNavii Mentor (SD Biosensor Inc, Korea). The study procedures were based on International Organization for Standardization 15197:2013, in that capillary blood samples from 100 participants’ fingertips were measured with three reagent system lots of the self-monitoring blood glucose system. Samples were collected for comparison measurements on a hexokinase-based glucose analyzer (Cobas Integra400 Plus, Roche Instrument Center, Switzerland). Glucose concentrations were distributed as required by International Organization for Standardization 15197. For each of the 100 evaluable samples, duplicate measurements were taken from three different reagent lots, for a total of 600 measurements. Overall, 98.3% (590/600) of individual measurement results (185/186, 99.5% for glucose values <100 mg/dl and 405/414, 97.8% for glucose values ≥100 mg/dl) were within ±15 mg/dl or ±15% of the corresponding comparison method results. All results (100%) fell into the consensus error grid zones A and B, indicating only clinically acceptable results. In conclusion, the blood glucose monitoring system SD GlucoNavii Mentor device fulfilled the system accuracy criteria of the International Organization for Standardization 15197, indicating measurement accuracy sufficient for diabetes therapy.

Iterative learning based consensus control for distributed parameter type multi‐agent differential inclusion systems

AbstractThis article considers the learning consensus problem of distributed parameter type multi‐agent differential inclusion systems including parabolic type and hyperbolic type. By imposing a Lipschitz condition on a set‐valued mapping and utilizing distributed ‐type iterative learning consensus control protocols, an iterative learning process is established. Further, sufficient conditions for the convergence of the consensus error between any two agents in the sense of the certain norm are obtained with the help of Steiner‐type selectors. Finally, numerical simulations verify the validity of the proposed method.

Finite-Time Leader-Following Consensus of Multiagent Systems With Actuator Faults and Input Saturation

This article studies the fault-tolerant leader-following consensus problem for multiagent systems with input saturation. The main contribution is to present a modified low-and-high gain feedback approach to deal with multiple actuator faults, including partial loss of effectiveness, outage, and stuck simultaneously. First, without consideration of saturation, a distributed fault-tolerant control scheme is put forward by the adaptive technique, and a practical finite-time stability result is established. Second, by employing the fault-tolerant theory and introducing a novel form of parametric algebraic Riccati equation, a modified low-and-high gain feedback approach is developed for the saturated control strategy. It is proven that the practical finite-time stability can be achieved, and both the steady-state consensus error and the settling time can be well estimated. Finally, numerical simulations are provided to validate the effectiveness of the theoretical results.

Consensus control of cooperation‐competition multi‐agent systems with round‐robin protocols: A set‐membership approach

AbstractThis paper is concerned with the set‐membership consensus of cooperation‐competition multi‐agent systems (CCMASs) with the round‐robin (RR) protocol. First, the relationship between cooperative and competitive agents is featured by the graph theory. Second, the RR protocol is used to relieve the burden of data transmission among agents due to the limited network bandwidth. Third, a novel concept of set‐membership consensus for CCMASs is presented to disclose the bound of consensus errors. In the framework of set‐membership filtering, a novel co‐design framework of set‐membership estimation and set‐membership consensus is provided to realize the desired cooperation‐competition consensus, where an ellipsoid is obtained to estimate the agent state. The controller and observer gains as well as the ellipsoid parameters are obtained by a recursive convex optimization algorithm. Finally, an illustrated example is given to demonstrate the effectiveness of the proposed method.

Glucose meter standardization across a large academic hospital system

BackgroundTo select and standardize point-of-care (POC) glucose meters across a multi-hospital system. MethodsWe formed a multidisciplinary POC glucose standardization working group including key stakeholders from each site. A set of selection criteria: usability, clinical and laboratory performance, indications for use, interface connectivity, ease of implementation and ongoing operational costs were used to develop a scoring schemato facilitate a consensus-driven selection process. ResultsMethod comparison and consensus error grid evaluation against the clinically validated reference methods demonstrated that the analytical performance for all candidate meters was comparable for both the laboratory and clinical evaluation. However, Meter 1 ranked highest in usability evaluations, implementation and streamlined interface connectivity. The meter selection process and implementation were staggered across sites due to complexity of transitioning to a new manufacturer’s meter and limitations in vendor support for training and ongoing troubleshooting of interface connectivity. ConclusionsStandardization of POC glucose meters in a large multi-hospital system is a complex undertaking requiring robust, multidisciplinary organizational structure both system-wide and locally, development of consensus-driven selection tools, usability evaluation by end-users, laboratory and clinical evaluation of the analytical performance, and a strong vendor-laboratory partnership during the implementation process.

Sampled-Data Leaderless and Leader-Following Consensus of Multiagent Systems Under Nonidentical Packet Losses

In this work, the leaderless and leader-following consensus problems are investigated for multiagent systems (MAS) with asynchronous sampling mechanism and nonidentical packet losses. First, distributed sampled-data control protocols are proposed based on estimators, the estimator's state is updated according to whether packet losses occur in certain communication channel. Then, by defining appropriate consensus error variables and by means of internal auxiliary variables, a unified hybrid model consisting of flow dynamics and jump dynamics is constructed for both leaderless and leader-following MAS, such that leaderless and leader-following consensus of MAS can be dealt with in a unified framework. Based on this model, a hybrid system approach is proposed for stability analysis and linear matrix inequality based stability conditions are derived. The interaction relationship among sampling period, the number of successive packet losses, and design parameters is explicitly characterized. The effectiveness of the proposed method is illustrated via numerical simulation.

Optimality Condition and Distributed Optimization for Economic Dispatch Using a Novel Weighted Incremental Cost Consensus Approach

This research report investigates a novel optimization approach for the economic dispatch problem (EDP) based on the weighted sum of generators’ costs under supply-demand balance. Unlike conventional approaches, we present a distributed optimization approach that ensures optimality using weighted incremental cost (IC) consensus and sign-consensus error convergence. We can apply the optimization of a weighted sum of generators’ costs to address several constraints, such as capacity and environmental constraints, in addition to the supply-demand balance. The proposed distributed weighted incremental cost consensus approach has been applied to the IEEE-30 bus and IEEE-118 bus systems over a communication topology. The results indicate the efficacy of weights to address generation constraints and the convergence of weighted ICs under supply-demand balance.

Accuracy Assessment of the GlucoMen® Day CGM System in Individuals with Type 1 Diabetes: A Pilot Study.

The aim of this study was to evaluate the accuracy and usability of a novel continuous glucose monitoring (CGM) system designed for needle-free insertion and reduced environmental impact. We assessed the sensor performance of two GlucoMen® Day CGM systems worn simultaneously by eight participants with type 1 diabetes. Self-monitoring of blood glucose (SMBG) was performed regularly over 14 days at home. Participants underwent two standardized, 5-h meal challenges at the research center with frequent plasma glucose (PG) measurements using a laboratory reference (YSI) instrument. When comparing CGM to PG, the overall mean absolute relative difference (MARD) was 9.7 [2.6–14.6]%. The overall MARD for CGM vs. SMBG was 13.1 [3.5–18.6]%. The consensus error grid (CEG) analysis showed 98% of both CGM/PG and CGM/SMBG pairs in the clinically acceptable zones A and B. The analysis confirmed that GlucoMen® Day CGM meets the clinical requirements for state-of-the-art CGM. In addition, the needle-free insertion technology is well tolerated by users and reduces medical waste compared to conventional CGM systems.

Secure consensus control for multi‐agent systems against attacks on actuators and sensors

AbstractThis article studies the secure leader‐following consensus control problem for discrete‐time multi‐agent systems under false data injection (FDI) attacks on both actuators and sensors. It is shown that under standard consensus protocol, an attacked follower can cause normal followers to fail to follow the leader if the normal followers can access the attacked follower through directed paths of arbitrary length. To mitigate the adverse impacts of FDI attacks, a secure observer‐based consensus protocol is presented where local observer is used to estimate the system state and attack signal simultaneously and then the uniformly ultimately boundedness of state consensus error between all followers and leader can be guaranteed. Finally, a simulation example on the LC oscillator networks in the presence of FDI attacks validates the unavailability of standard consensus protocol and the effectiveness of the proposed secure observer‐based consensus protocol.

Hybrid Event-Triggered Approach for Quasi-Consensus of Uncertain Multi-Agent Systems With Impulsive Protocols

Quasi-consensus tracking problems of uncertain multi-agent systems are investigated in this paper. By integrating impulsive control theory with event-triggered mechanism, a new hybrid event-triggered impulsive consensus protocol is presented, under which the information transmission of agents occurs at a sequence of state-dependent instants. Based on Lyapunov method, several quasi-consensus criteria of uncertain multi-agent systems are constructed, as well as the relation among control gains, event parameters, consensus error level, and convergence rate is established. It shows that the hybrid event-triggered control strategy benefits to save the energy cost of information transmission and control cost between agents compared with the time-triggered scheme, and it is effective to achieve quasi-consensus tracking objective of considered systems. Finally, the Zeno behavior is shown to be ruled out, and some simulation examples are proposed to demonstrate the validity of the theoretical analysis.

The fault-tolerant consensus strategy for leaderless Multi-AUV system on heterogeneous condensation topology

The present paper proposes a distributed fault-tolerant consensus control protocol strategy for leaderless multi-autonomous underwater vehicle (AUV) systems, where actuators have a partial break-down. Instead of the global information, this strategy applies the relative state of the topology. Also, the topology graph can be any heterogeneous condensation digraph with a spanning tree in the communication network. The linear feedback technique is used to linearize the system model into a second-order multi-AUV system. Then, the Lyapunov functional method is used to prove the system's stability and astringency and the algorithm's effectiveness is simulated numerically. It was found that the actuator efficiency could not be the same in each AUV. Also, the partial actuator loss of effectiveness faults is more typical and complicated. In addition, each AUV's state can converge to the same asymptote, and the consensus error can converge to zero.

Observer-based H∞ consensus for linear multi-agent systems subject to measurement outliers

The consensus problem has a crucial role in theoretical and practical aspects of interconnected systems, for instance in smart computing field. This paper is concerned with the observer-based H∞ consensus problem for a class of linear multi-agent systems subject to measurement outliers. In the addressed observer-based H∞ consensus problem, measurement outliers can affect the estimation accuracy and thus affect the consensus performance. To assuage the impact of measurement outliers, a control protocol based on an observer containing a saturation function with variable saturation limits is proposed. The purpose of this paper is to find a solution to the addressed H∞ consensus problem for a class of linear multi-agent systems subject to measurement outliers by designing an observer-based control protocol such that multi-agent systems can fulfill the H∞ consensus performance over a finite horizon. With the aid of Lyapunov theory, the sufficient condition is established to guarantee that the consensus error dynamic system satisfies the H∞ consensus performance. Then, the linear matrix inequality (LMI) approach is used to obtain the desired parameters of the observer-based control protocol. Finally, the effectiveness of the proposed control protocol is verified in a simulation environment. Aim: The purpose of this study is to find a solution to the addressed H∞ consensus problem for a class of linear multi-agent systems subject to measurement outliers. Methods: By choosing a suitable Lyapunov function, the sufficient condition is obtained, which can guarantee the consensus error dynamic system satisfying the given H∞ consensus performance. The LMI approach is employed to design the desired controller. With Matlab LMI toolbox, a numerical example was conducted to demonstrate the effectiveness of the proposed observer-based control protocol in the simulation environment. Results: A satisfactory consensus performance can be guaranteed for multi-agent systems subject to measurement outliers under the proposed observer-based control protocol. The constructed saturation function with variable saturation limits can mitigate the effect of measurement outliers by dynamically regulating saturation limits. Compared with the traditional observer-based control protocol, in this paper, the proposed observer-based control protocol shows robustness against measurement outliers. Conclusion: A solution to the addressed multi-agent consensus problem subject to measurement outliers was found by designing an observer-based consensus controller. The obtained results can be extended to sensor networks, neural networks, and nonlinear multi-agent systems.

Distributed Consensus Control of Networked Robotic Systems With Dynamic Leader Under Time-Varying Delays and Denial-of-Service Attacks

Consensus of multi-agent systems has a wide range of applications, such as coordination, cooperative transportation, and synchronization. This study investigates consensus control in the task space of multi-robotic systems modeled using Euler-Lagrange equations with a moving leading under time-varying delays and denial-of-service (DoS) attacks, respectively. Two control algorithms are studied when networked robotic systems are interconnected over directed spanning trees with a constant-velocity leader as the root. First, we use the Lyapunov-Razumikhin theorem to address a condition of the maximum time delay for nonuniform time-delay communication, thereby ensuring asymptotic tracking of the network. Second, we propose a novel resilient control framework to deal with DoS attacks. Note that designing the control algorithm for DoS attacks is difficult because the attacks cause signal discontinuity. The proposed resilient controller can release the DoS duration condition, which is a common requirement in many related works. It is verified that the consensus errors converge to the origin under the proposed control frameworks. We present experimental results to demonstrate the effectiveness of the proposed controllers.

Distributed Predefined-Time Attitude Consensus Control for Multiple Uncertain Spacecraft Formation Flying

This paper addresses the distributed predefined-time attitude consensus problem for multiple uncertain spacecraft systems in the presence of model uncertainties and external disturbances. Firstly, a new predefined-time terminal sliding surface (PTS) is proposed. Secondly, a distributed predefined-time consensus control (DPTC) based on the PTS is designed to solve the robust attitude consensus problem. It is proved that the proposed DPTC can ensure that the attitude consensus errors converge to an arbitrary small bound centered on equilibrium point within predefined time and then go to equilibrium point asymptotically. The appealing features of the proposed control are faster convergence, higher precision, stronger robustness and easy implementation. Simulations verify the effectiveness of the proposed approach.

Consensus stability analysis for stochastic multi-agent systems with multiplicative measurement noises and Markovian switching topologies

&lt;p style='text-indent:20px;'&gt;We investigate the consensus stability for linear stochastic multi-agent systems with multiplicative noises and Markovian random graphs and investigate the asymptotic consensus in the mean square sense for the systems. To establish the consensus stability for the systems, we analysis the consensus error systems by developing general stochastic differential equation with jumps, matrix theory and algebraic graph theory, and then show that the error consensus in the mean square sense finally tending to zero as time goes on is determined by the strongly connected property of union of topologies. Finally, we provide an example to demonstrate the effectiveness of our theoretical results.&lt;/p&gt;

A Hybrid Predictive Type-3 Fuzzy Control for Time-Delay Multi-Agent Systems

In this paper, the consensus problem is addressed for multi-agent systems. The dynamics of each agent contain unknown uncertain/nonlinear terms and unknown time delays. A type-3 fuzzy logic system is developed to tackle the effect of unknown dynamics and design a hybrid controller. The policy scheme involves two control signals for the stabilization of the approximation and consensus error of each agent dynamic. To this end, based on the concept of the model predictive control approach, the constrained control laws are designed and updated at each time step. The simulations results portray the error signals. Feasibility, appropriate convergence, and proper transient response are the main merits of the suggested method.

Leader-following consensus control of multiple nonholomomic mobile robots: An iterative learning adaptive control scheme

In this paper, the distributed iterative learning control for nonholonomic mobile robots with a time-varying reference is investigated, in which the mobile robots are with parametric uncertainties and are not fully actuated. Besides, the control gains of mobile robots are unknown. The leader is with a time-varying reference trajectory, and there is no need to assume that the time-varying reference is linearly parameterized by a set of known functions. A distributed control scheme is designed for each mobile robot based on a set of local compensatory filters designed by its neighborhood information. Stability analysis is established through a set of composite energy function. The uniform convergence of the consensus errors can be guaranteed. An example is given to show that our designed control law is effective.

Dynamic event-triggered output consensus of nonstrict-feedback MASs with predefined performance

This paper deals with the output consensus problem for uncertain nonstrict-feedback leader-follower multi-agent systems with predefined performance. A distributed event-triggered control strategy with dynamic threshold is proposed to update the actual control input and alleviate the computation burden of the communication procedure effectively. The unknown nonstrict-feedback structures are addressed by using the property of radial basis function neural networks. It is worth noting that in practical applications, the predefined performance often alternates between constrained and unconstrained cases in some extreme situations. To overcome this challenge, a novel coordinate transformation technique is incorporated to tackle both the two cases with and without performance constraint in a unified manner. As a result, the proposed event-triggered control approach ensures that the output consensus errors converge to zero asymptotically, and all the signals in the closed-loop system are bounded. Finally, the effectiveness of the proposed protocol is demonstrated by the simulation results.

Adaptive Iterative Learning Control of Multiple Autonomous Vehicles With a Time-Varying Reference Under Actuator Faults.

In this article, a distributed adaptive iterative learning control for a group of uncertain autonomous vehicles with a time-varying reference is presented, where the autonomous vehicles are underactuated with parametric uncertainties, the actuators are subject to faults, and the control gains are not fully known. A time-varying reference is adopted, the assumption that the trajectory of the leader is linearly parameterized with some known functions is relaxed, and the control inputs are smooth. To design distributed control scheme for each vehicle, a local compensatory variable is generated based on information collected from its neighbors. The composite energy function is used in stability analysis. It is shown that uniform convergence of consensus errors is guaranteed. An illustrative example is given to demonstrate the effectiveness of the proposed control scheme.

Consensus Sliding-Mode Fault-Tolerant Control for Second-Order Multi-Agent Systems

This study investigates the consensus problem of second-order nonlinear multi-agent systems (MASs) with actuator faults via a sliding mode control approach. The consensus error dynamic is given based on the relative states of the neighbors. Then, a sliding mode surface based on consensus errors is proposed, and the asymptotic stability of the sliding mode is proved using the Lyapunov theory. Furthermore, a sliding-mode fault-tolerant consensus protocol is proposed to compensate for actuator faults. According to the sliding mode control theory, the proposed sliding-mode fault-tolerant controller ensures that the consensus of the MASs can be reached in a finite time. Finally, a simulation example of a second-order multi-robot system is presented to demonstrate the effectiveness of the proposed controller.