다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

This paper deals with the lateral motion control of four-wheel-independent-drive electric vehicles (4WID-EVs) subject to onboard network-induced time delays. It is well known that the in-vehicle network and x-by-wire technologies have considerable advantages over the traditional point-to-point communication. However, on the other hand, these technologies would also induce the probability of time-varying delays, which would degrade control performance or even deteriorate the system. To enjoy the advantages and deal with in-vehicle network delays, an H∞-based delay-tolerant linear quadratic regulator (LQR) control method is proposed in this paper. The problem is described in the form of an augmented discrete-time model with uncertain elements determined by the delays. Delay uncertainties are expressed in the form of a polytope using Taylor series expansion. To achieve a good steady-state response, a generalized proportional-integral control approach is adopted. The feedback gains can be obtained by solving a sequence of linear matrix inequalities (LMIs). Cosimulations with Simulink and CarSim demonstrate the effectiveness of the proposed controller. Comparison with a conventional LQR controller is also carried out to illustrate the strength of explicitly dealing with in-vehicle network delays.

Combined AFS and DYC Control of Four-Wheel-Independent-Drive Electric Vehicles over CAN Network with Time-Varying Delays

This paper considers the event-triggered tracking control problem of nonlinear multiagent systems with unknown disturbances. The event-triggering mechanism is considered in the controller update, which decreases the amount of communication and reduces the frequency of the controller update in practice. By designing a disturbance observer, the unknown external disturbances are estimated. Moreover, a part of adaptive parameters are only dependent on the number of followers, which weakens the computational burden. It is shown that all the signals are bounded, and the consensus tracking errors are located in a small neighborhood of the origin based on the Lyapunov stability theory and backstepping approach. Finally, the effectiveness of the approach proposed in this paper is proved by simulation results.

Event-Triggered Adaptive Tracking Control for Multiagent Systems With Unknown Disturbances

Adaptive control methods are developed for stability and tracking control of flight systems in the presence of parametric uncertainties. This paper offers a design technique of adaptive sliding mode control (ASMC) for finite-time stabilization of unmanned aerial vehicle (UAV) systems with parametric uncertainties. Applying the Lyapunov stability concept and finite-time convergence idea, the recommended control method guarantees that the states of the quad-rotor UAV are converged to the origin with a finite-time convergence rate. Furthermore, an adaptive-tuning scheme is advised to guesstimate the unknown parameters of the quad-rotor UAV at any moment. Finally, simulation results are presented to exhibit the helpfulness of the offered technique compared to the previous methods.

Adaptive sliding mode control for finite-time stability of quad-rotor UAVs with parametric uncertainties.

This paper is concerned with event-triggered consensus of general linear multiagent systems (MASs) in leaderless and leader-following networks, respectively, in the framework of adaptive control. A distributed dynamic event-triggered strategy is first proposed, in which an auxiliary parameter is introduced for each agent to regulate its threshold dynamically. The time-varying threshold ensures less triggering instants, compared with the traditional static one. Then under the proposed event-triggered strategy, a distributed adaptive consensus protocol is formed including the updating law of the coupling strength for each agent. Some criteria are derived to guarantee leaderless or leader-following consensus for MASs with general linear dynamics, respectively. Moreover, it is proved that the triggering time sequences do not exhibit Zeno behavior. Finally, the effectiveness of the proposed dynamic event-triggered control mechanism combined with adaptive control is validated by two examples.

Adaptive Consensus Control of Linear Multiagent Systems With Dynamic Event-Triggered Strategies

This paper investigates a novel integral sliding mode control (ISMC) strategy for the waypoint tracking control of a quadrotor in the presence of model uncertainties and external disturbances. The proposed controller has the inner–outer loop structure: The outer loop is to generate the reference signals of the roll and pitch angles, while the inner loop is designed by using the ISMC technique for the quadrotor to track the desired $x$ , $y$ positions and roll and pitch angles. The Lyapunov stability analysis is provided to show that the negative effects of the bounded model uncertainties and external disturbances can be significantly decreased. The designed controller is then applied to a heterogeneous multi-agent system (MAS) consisting of quadrotors and two-wheeled mobile robots (2WMRs) to solve the consensus problem. We present the control algorithms for the 2WMRs and quadrotors. Consensus of the heterogeneous MAS can be reached if the switching graphs always have a spanning tree. Finally, the experimental tests are conducted to verify the effectiveness of the proposed control methods.

Integral Sliding Mode Flight Controller Design for a Quadrotor and the Application in a Heterogeneous Multi-Agent System

In this paper, we use an event-triggered control methode to study the consensus problem for an asynchronous distributed multi-agent system. An integral-type event-triggering condition is proposed. Each agent periodically checks its triggering condition by its own clock. When the triggering condition for an agent is satisfied, then control inputs of this agent and its neighbors are updated. Based on local information, we present the consensus protocol, and using Lyapunov's methods, we show that all agents asymptotically reach an agreement on states. Finally, experiments are presented to demonstrate the effectiveness of our proposed protocol.

Consensus Control for a Multi-Agent System With Integral-Type Event-Triggering Condition and Asynchronous Periodic Detection

This paper investigates the consensus problem for a group of two-wheeled mobile robots (2WMRs) using nonuniform sampling. The directed and switching communication topologies are considered. The control protocols for the first-order/second-order system dynamics are designed with bounded control gains. The RotateR 2) the vehicle rotates in place until it aims at the calculated direction; and 3) the vehicle moves forward/backward with the calculated wheel velocities until the next sampling time instant. It is shown that consensus in a group of 2WMRs can be achieved when the switching directed graphs satisfy certain conditions. The convergence analysis of consensus is conducted based on the algebraic graph theory and stochastic matrix analysis. Experiments demonstrate the effectiveness of the proposed methods.

Design and Implementation of Nonuniform Sampling Cooperative Control on A Group of Two-Wheeled Mobile Robots

Image noise smoothing using a modified Kalman filter

Cooperative control of multi-agent systems (MASs) has been intensively investigated in the past decade. The task is always complicated for an individual agent, but can be achieved by collectively operating a group of agents in a reliable, economic and efficient way. Although a lot of efforts are being spent on improving MAS performances, much progress has yet to be developed on different aspects. This thesis aims to solve problems in the consensus control of multiple quadrotors and/or mobile robots considering irregular sampling controls, heterogeneous agent dynamics and the presence of model uncertainties and disturbances. The thesis proceeds with Chapter 1 by providing the literature review of the state-of-the-art development in the consensus control of MASs. Chapter 2 introduces experimental setups of the laboratory involving two-wheeled mobile robots (2WMRs), quadrotors, positioning systems and inter-vehicle communications. All of the developed theoretical results in Chapters 3-6 are experimentally verified on the platform. Then it is followed by two main parts: Irregular sampling consensus control methods (Chapter 3 and 4) and cooperative control of heterogeneous MASs (Chapter 5 and 6). Chapter 3 focuses on the non-uniform sampling consensus control for a group of 2WMRs, and Chapter 4 studies the event-based rendezvous control for a group of asynchronous robots with time-varying communication delays. Chapter 5

Bingxian Mu

Papers

Integral Sliding Mode Flight Controller Design for a Quadrotor and the Application in a Heterogeneous Multi-Agent System

Consensus Control for a Multi-Agent System With Integral-Type Event-Triggering Condition and Asynchronous Periodic Detection

Design and Implementation of Nonuniform Sampling Cooperative Control on A Group of Two-Wheeled Mobile Robots

Image noise smoothing using a modified Kalman filter

Cooperative control of quadrotors and mobile robots: controller design and experiments