In this paper, a design method is presented for path-following control of underactuated autonomous underwater vehicles subject to velocity and input constraints, as well as internal and external disturbances. In the guidance loop, a kinematic control law of the desired surge speed and pitch rate is derived based on a backstepping technique and a line-of-sight guidance principle. In the control loop, an extended state observer is developed to estimate the extended state composed of unknown internal dynamics and external disturbances. Then, a disturbance rejection control law is constructed using the extended state observer. To bridge the guidance loop and the control loop, a reference governor is proposed for computing optimal guidance signals within the velocity and input constraints. The reference governor is formulated as a quadratically constrained optimization problem. A projection neural network is employed for solving the optimization problem in real time. Simulation results illustrate the effectiveness of the proposed method for path-following control of autonomous underwater vehicles subject to constraints and disturbances simultaneously in the vertical plane.
We study a class of compact surfaces in $\mathbb R^3$ introduced by Alexandrov and generalized by Nirenberg and prove a compactness result under suitable assumptions on induced metrics and Gauss curvatures.
This article is concerned with distributed dynamic event-triggered Nash equilibrium seeking in merely monotone games under switching communication topologies. B
This paper is concerned with a hierarchical distributed receding horizon control (HDRHC) approach, by which a global objective of locating the peaks of an unknown environment of interest can be achieved among locally communicating agents. The proposed HDRHC approach is executed by each agent independently and consists of two levels. In the first level, a radial basis function network is used to model the unknown environment of interest. On the basis of the established environment model, a dynamical optimization problem is formulated and solved by using a receding horizon control approach such that an ideal movement trajectory for each agent is generated. The agents can trace the peaks of the environment of interest by moving along the ideal movement trajectory; however, the collision among agents may occur. In the second level, a cooperative control optimization problem, whose aim is to avoid collision among agents, is designed. Hence, the real movement trajectory of each agent, which is produced by using the receding horizon control approach, not only should minimize the cooperative control optimization problem, but also should be close to the ideal movement trajectory. Finally, the effectiveness of the proposed HDRHC approach is illustrated for the gradient climbing problem.
This paper considered with the finite-time consensus for multi-agent systems (MASs) with discontinuous dynamics over switching topology. A novel discontinuous control protocol is designed to achieved the finite-time consensus. Then, together with Lyapunov function method and finite-time stability theory, several sufficient conditions are derived to guarantee the MASs networks to be finite-time consensus. Moreover, an upper bound of the settling time can be theoretically estimated.
In this article, the tracking control problem is investigated for a type of linear networked systems subject to the round-Robin (RR) protocol scheduling and impulsive transmission outliers (ITOs). The communication between the controller and sensors is implemented through a shared network, on which the signal transmissions are scheduled by the RR protocol. The considered ITOs are modeled by a sequence of impulsive signals whose amplitudes (i.e., the norms of all impulsive signals) and interval lengths (i.e., the duration between all adjacent impulsive signals) are greater than two known thresholds, respectively. The occurrence moment for each ITO is first examined by using a certain outlier detection approach, and then a novel parameter-dependent tracking controller is proposed to protect the tracking performance from ITOs by removing the "harmful" signals (i.e., the transmitted signals contaminated by ITOs). Sufficient conditions are presented to ensure the exponentially ultimate boundedness of the resulted tracking error, and the controller gain matrices are subsequently designed by solving a constrained optimization problem. Finally, a simulation example is provided to demonstrate the effectiveness of our developed outlier-resistant tracking control scheme.
This brief considers the fixed-time bipartite consensus tracking problem of a fractional-order multiagent system (FOMAS) with a dynamic leader in a general directed signed network. Firstly, by introducing a neighborhood-based variable, the FOMAS is transformed into an integer-order MAS. Then, a distributed protocol with heterogeneous coupling gains is proposed to ensure that the fixed-time bipartite consensus tracking can be achieved within a settling time. The upper bound of the settling time can be estimated explicitly, which is irrelevant to any initial conditions. Finally, the effectiveness of the proposed distributed protocol is illustrated by numerical simulation.
This paper is concerned with the event-triggered control problem of vehicle active suspension systems subject to uncertain actuator faults. Firstly, networked modeling of the vehicle suspension control system is presented and a dynamic event-triggered communication mechanism is developed to reduce some unnecessary data transmissions between networked sensor and controller, thus enabling efficient usage of the limited communication resources for the in-vehicle network. Different from most existing event-triggered mechanisms, the threshold parameter of the proposed triggering condition is adaptively regulated in accord with a dynamic rule. Secondly, by Lyapunov functional method, a co-design criterion of the desired event-triggering parameter and H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> controller gain is derived so as to guarantee the asymptotic stability of the resulting closed-loop system and preserve several performance requirements of the suspension system, including ride comfort, road holding and suspension deflection/stroke limitation. Finally, simulation results are provided to show the effectiveness of the proposed method.
This paper is concerned with the problem of robust H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">infin </sub> control for a class of uncertain time-delay fuzzy systems. The time-delay is assumed to be a time-varying continuous function belonging to a given interval, which means that the lower and upper bounds for the time-varying delay are available. No restriction on the derivative of the time-varying delay is needed, which allows the time-delay to be a fast time-varying function. The Takagi-Sugeno (T-S) uncertain fuzzy model with interval time-varying delay is adopted. Based on the Lyapunov-Krasovskii functional approach, some delay-dependent conditions for the existence of robust H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">infin</sub> controller are formulated in the form of linear matrix inequalities (LMIs). When these LMIs are feasible, an H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">infin</sub> controller is presented. A numerical example is given to demonstrate the effectiveness of the proposed method
This paper is concerned with sampled-data leader-following consensus of a group of agents with nonlinear characteristic. A distributed consensus protocol with probabilistic sampling in two sampling periods is proposed. First, a general consensus criterion is derived for multiagent systems under a directed graph. A number of results in several special cases without transmittal delays or with the deterministic sampling are obtained. Second, a dimension-reduced condition is obtained for multiagent systems under an undirected graph. It is shown that the leader-following consensus problem with stochastic sampling can be transferred into a master-slave synchronization problem with only one master system and two slave systems. The problem solving is independent of the number of agents, which greatly facilitates its application to large-scale networked agents. Third, the network design issue is further addressed, demonstrating the positive and active roles of the network structure in reaching consensus. Finally, two examples are given to verify the theoretical results.
One of the fundamental and challenging issues in microgrids is to guarantee fairness of load sharing while realizing voltage regulation of distributed generations. In order to address this issue, a new multiobjective optimization problem with tunable weighting coefficients is first formulated for dc microgrids. Second, a new distributed control scheme, which only requires local communications among neighbors, is proposed to solve the optimization problem. It is theoretically proved that the distributed control scheme can exponentially achieve the global optimal outputs of voltages and currents at distributed generations. Compared with a centralized control scheme, the proposed distributed control scheme provides remarkable advantages in improving reliability and scalability of microgrids. Third, the distributed control scheme is extended to accommodate a constant communication delay. The effects of the communication delay on the stability of microgrids are explicitly characterized. Finally, the performance of the proposed control schemes is evaluated by a modified six-bus microgrid with dc-powered trolleybus systems in terms of their convergence, robustness to load variations, plug-and-play functionality, tradeoff ability, and effects of communication delays.
