402 research outputs found
Optimal Rejection of Bounded Perturbations in Linear Leader-Following Consensus Protocol: Method Invariant Ellipsoid
The objective of the invariant ellipsoid method is to minimize the smallest
invariant and attractive set of a linear control system operating under the
influence of bounded external disturbances. In this paper, this method is
extended into the leader-following consensus problem. Initially, a linear
control protocol is designed for the Multi-agent System without disturbances.
Subsequently, in the presence of bounded disturbances, by employing a similar
linear control protocol, a necessary and sufficient condition is introduced to
derive the optimal control parameters for the MAS such that the state of
followers converge and remain in an minimal invariant ellipsoid around the
state of the leader
Space-and-time-synchronized simultaneous vehicle tracking/formation using cascaded prescribed-time control
In this paper, we present a space-and-time-synchronized control method with
application to the simultaneous tracking/formation. In the framework of polar
coordinates, through correlating and decoupling the reference/actual kinematics
between the self vehicle and target, time and space are separated, controlled
independently. As such, the specified state can be achieved at the
predetermined terminal time, meanwhile, the relative trajectory in space is
independent of time. In addition, for the stabilization before the predesigned
time, a cascaded prescribed-time control theorem is provided as the preliminary
of vehicle tracking control. The obtained results can be directly extended to
the simultaneous tracking/formation of multiple vehicles. Finally, numerical
examples are provided to verify the effectiveness and superiority of the
proposed scheme.Comment: 10 pages, 5 figures. International Journal of Robust and Nonlinear
Control 202
Distributed Sliding-Mode Formation Controller Design for Multirobot Dynamic Systems
This paper presents a distributed formation control for multirobot dynamic systems with external disturbances and system uncertainties. First from the Lagrangian analysis, the dynamic model of a wheeled mobile robot can be derived. Then, the robust distributed formation controller is proposed based on sliding-mode control, consensus algorithm, and graph theory. In this study, the robust stability of the closed-loop system is guaranteed by the Lyapunov stability theorem. From the simulation results, the proposed approach provides better formation responses compared to consensus algorithm
Cooperative Control of Nonlinear Multi-Agent Systems
Multi-agent systems have attracted great interest due to their potential applications in a variety of areas. In this dissertation, a nonlinear consensus algorithm is developed for networked Euler-Lagrange multi-agent systems. The proposed consensus algorithm guarantees that all agents can reach a common state in the workspace. Meanwhile, the external disturbances and structural uncertainties are fundamentally considered in the controller design. The robustness of the proposed consensus algorithm is then demonstrated in the stability analysis. Furthermore, experiments are conducted to validate the effectiveness of the proposed consensus algorithm.
Next, a distributed leader-follower formation tracking controller is developed for networked nonlinear multi-agent systems. The dynamics of each agent are modeled by Euler-Lagrange equations, and all agents are guaranteed to track a desired time-varying trajectory in the presence of noise. The fault diagnosis strategy of the nonlinear multi-agent system is also investigated with the help of differential geometry tools. The effectiveness of the proposed controller is verified through simulations.
To further extend the application area of the multi-agent technique, a distributed robust controller is then developed for networked Lipschitz nonlinear multi-agent systems. With the appearance of system uncertainties and external disturbances, a sampled-data feedback control protocol is carried out through the Lyapunov functional approach. The effectiveness of the proposed controller is verified by numerical simulations. Other than the robustness and sampled-data information exchange, this dissertation is also concerned with the event-triggered consensus problem for the Lipschitz nonlinear multi-agent systems. Furthermore, the sufficient condition for the stochastic stabilization of the networked control system is proposed based on the Lyapunov functional method. Finally, simulation is conducted to demonstrate the effectiveness of the proposed control algorithm.
In this dissertation, the cooperative control of networked Euler-Lagrange systems and networked Lipschitz systems is investigated essentially with the assistance of nonlinear control theory and diverse controller design techniques. The main objective of this work is to propose realizable control algorithms for nonlinear multi-agent systems
Fixed-time safe tracking control of uncertain high-order nonlinear pure-feedback systems via unified transformation functions
summary:In this paper, a fixed-time safe control problem is investigated for an uncertain high-order nonlinear pure-feedback system with state constraints. A new nonlinear transformation function is firstly proposed to handle both the constrained and unconstrained cases in a unified way. Further, a radial basis function neural network is constructed to approximate the unknown dynamics in the system and a fixed-time dynamic surface control (FDSC) technique is developed to facilitate the fixed-time control design for the uncertain high-order pure-feedback system. Combined with the proposed unified transformation function and the FDSC technique, an adaptive fixed-time control strategy is proposed to guarantee the fixed-time tracking. The novel original results of the paper allow to design the independent unified flexible fixed-time control strategy taking into account the actual possible constraints, either present or missing. Numerical examples are presented to demonstrate the proposed fixed-time tracking control strategy
Synchronous control of double-containers for overhead crane
The development and wide application of double spreaders overhead cranes have
effectively improved the loading and unloading efficiency of the container terminals.
However, due to the nonlinear time-varying characteristics and parameter perturbation
of the lifting device of the double spreaders, the difficulty of synchronous and
coordinated control of the double spreader overhead crane is increased. In order to solve
the problem of synchronous control of double spreaders overhead cranes, this work
establishes the mathematical model of the double spreaders overhead crane and
proposes two main methods. The controller based on the fuzzy sliding mode method is
established. Fuzzy logic control can effective estimate the parameters of the system,
reduce the chattering of sliding mode control, and improve the performance of its
control. Mean deviation coupling synchronization control combined with sliding mode
control can effectively control the speed error between the two spreaders, so that they
can keep working synchronously. The other controller is established which use fast
non-singular terminal sliding mode control to ensure that the system can converge in a
finite time. The combination of terminal sliding mode control and super twisting
algorithm can enhance the stability of the system.O desenvolvimento e a vasta aplicação de pontes rolantes de duplo espalhamento
tem melhorado a eficiência de carga e descarga dos terminais de contentores. No
entanto devido ao facto das variações não lineares do tempo e a perturbação dos
parâmetros do dispositivo de elevação de duplo espalhamento, é dificultado o controlo
sincronizado e coordenado. Com o objetivo de resolver o problema do controlo
síncrono das pontes rolantes de duplo espalhamento, este projeto usa o modelo
matemático do guindaste de dupla propagação e propõe dois métodos de resolução. O
controlo baseado no método do modo deslizante difuso. O controlo lógico difuso pode
estimar eficazmente os parâmetros do sistema, reduzir a vibração do controlo do modo
deslizante e melhorar o seu desempenho. O control de sincronização do acoplamento
do desvio médio, combinado com o control do modo deslizante que pode controlar
eficazmente o erro de velocidade entre os dois espalhadores, para que o seu trabalho
possa continuar de forma síncrona. O outro controlador usa um controlo rápido e não
singular do modo de deslizamento do terminal para garantir que o sistema possa
convergir num tempo limitado. A combinação do control no modo deslizante do
terminal e do algoritmo de super rotação pode melhorar a estabilidade do sistema
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