This paper addresses the problem of formation control and tracking a of desired trajectory by an Euler-Lagrange multi-agent systems. It is inspired by recent results by and adopts an event-triggered control strategy to reduce the number of communications between agents. For that purpose, to evaluate its control input, each agent maintains estimators of the states of the other agents. Communication is triggered when the discrepancy between the actual state of an agent and the corresponding estimate reaches some threshold. The impact of additive state perturbations on the formation control is studied. A condition for the convergence of the multi-agent system to a stable formation is studied. Simulations show the e ectiveness of the proposed approach.
Different formation-tracking methods have been considered. In leader-follower techniques @cite_29 @cite_6 @cite_43 @cite_20 , based on mission goals, a trajectory is designed only for some leader agent. The other follower agents, aim at tracking the leader as well as maintaining some target formation defined with respect to the leader. A virtual leader has been considered in @cite_0 @cite_6 @cite_25 to gain robustness to leader failure. This requires a good synchronization among agents of the state of the virtual leader. Virtual structures have been introduced in @cite_10 @cite_33 , where the agent control is designed to satisfy constraints between neighbours. Such approaches also address the problem of leader failure. In distance-based control, the constraints are distances between agents. In displacement-based control, relative coordinate or speed vectors between agents are imposed. In tensegrity structures @cite_4 @cite_11 additional flexibility in the structure is considered by considering attraction and repulsion terms between agents, as formalized by @cite_3 . In addition to constraints on the structure of the MAS, @cite_16 imposes some reference trajectory to each agent. In most of these works, permanent communication between agents is assumed.
@cite_4 @cite_33 @cite_29 @cite_6 @cite_3 @cite_0 @cite_43 @cite_16 @cite_10 @cite_25 @cite_20 @cite_11
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This paper investigates the distributed formation control problem for a group of mobile Euler-Lagrange agents to achieve global stabilization by using virtual tensegrity structures. Firstly, a systematic approach to design tensegrity frameworks is elaborately explained to confine the interaction relationships between agents, which allows us to obtain globally rigid frameworks. Then, based on virtual tensegrity frameworks, distributed control strategies are developed such that the mobile agents converge to the desired formation globally. The theoretical analysis is further validated through simulations. In the study of task coordination for multiagent systems, formation control has received considerable attention due to its potential applications in civil and or military prac-tices. Fundamentally, formation control problem for multiagent systems can be formulated as making a group of agents follow the desired trajectory while maintaining certain prescribed geometric distances among agents. In this paper, we consider the formation control problem for mobile robots with nonlinear dynamics and moving in a 2D environment. To address the inherent challenges due to nonlinear system dynamics and agents' limited sensing communication capabilities, we instill an idea of integrating the recently developed distributed consensus theory into the standard feedback control, and propose a new time-varying cooperative control strategy to solve the formation control problem for multiagent systems. In particular, the proposed design only requires the local and intermittent information exchange among agents to achieve the formation control objective. More importantly, we remove the restriction on the need of the desired trajectory for every agent, and instead design a distributed observer for obtaining the desired trajectory in order to establish the formation in the design. The overall distributed formation control system stability is rigorously proved by using a contraction mapping method under the condition that the sensing communication network among robots is sequentially complete. Simulation is provided to validate the effectiveness of the proposed design. A constructive method is presented to design cooperative controllers that force a group of N unicycle-type mobile robots with limited sensing ranges to perform desired formation tracking and guarantee no collisions between the robots. Physical dimensions and dynamics of the robots are also considered in the control design. Smooth and p times differential bump functions are introduced and incorporated into novel potential functions to design a formation tracking control system. Despite the robot limited sensing ranges, no switchings are needed to solve the collision avoidance problem. Simulations illustrate the results. We designed a distributed collision-free formation flight control law in the framework of nonlinear model predictive control. Formation configuration is determined in the virtual reference point coordinate system. Obstacle avoidance is guaranteed by cost penalty, and intervehicle collision avoidance is guaranteed by cost penalty combined with a new priority strategy. A collision-free formation flight controller for unmanned aerial vehicle (UAV) is designed in the framework of nonlinear model predictive control (MPC). It can consider control input saturation and state constraints explicitly. Formation configuration is determined based on virtual reference point method, which has no error propagation in the formation. The formation flight controller is designed in a distributed way. Based on the tracking error, the objective function for each UAV is designed in the nonlinear MPC framework. A new type of cost function, based on the UAV's velocity orientation and relative distance between UAV and obstacle, is added to the objective function to guarantee obstacle avoidance. Inter-vehicle collision avoidance is also ensured by cost function combined with a priority strategy. The nonlinear optimization problem is solved by the filter-SQP method, which has the better convergence and numeric. Simulation results are provided to evaluate the performance of the designed collision-free formation flight controller. In this paper, we present a synchronization approach to trajectory tracking of multiple mobile robots while maintaining time-varying formations. The main idea is to control each robot to track its desired trajectory while synchronizing its motion with those of other robots to keep relative kinematics relationships, as required by the formation. First, we pose the formation-control problem as a synchronization control problem and identify the synchronization control goal according to the formation requirement. The formation error is measured by the position synchronization error, which is defined based on the established robot network. Second, we develop a synchronous controller for each robot's translation to guarantee that both position and synchronization errors approach zero asymptotically. The rotary controller is also designed to ensure that the robot is always oriented toward its desired position. Both translational and rotary controls are supported by a centralized high-level planer for task monitoring and robot global localization. Finally, we perform simulations and experiments to demonstrate the effectiveness of the proposed synchronization control approach in the formation control tasks. Built on the combined strength of decentralized control and the recently introduced virtual structure approach, a decentralized formation scheme for spacecraft formation flying is presented. Following a decentralized coordination architecture via the virtual structure approach, decentralized formation control strategies are introduced, which are appropriate when a large number of spacecraft are involved and or stringent interspacecraft communication limitations are exerted. The effectiveness of the proposed control strategies is demonstrated through simulation results. In this note, we study a distributed coordinated tracking problem for multiple networked Euler-Lagrange systems. The objective is for a team of followers modeled by full-actuated Euler-Lagrange equations to track a dynamic leader whose vector of generalized coordinates is time varying under the constraints that the leader is a neighbor of only a subset of the followers and the followers have only local interaction. We consider two cases: i) The leader has a constant vector of generalized coordinate derivatives, and ii) The leader has a varying vector of generalized coordinate derivatives. In the first case, we propose a distributed continuous estimator and an adaptive control law to account for parametric uncertainties. In the second case, we propose a model-independent sliding mode control algorithm. Simulation results on multiple networked two-link revolute joint arms are provided to show the effectiveness of the proposed control algorithms. Using dynamic models of tensegrity structures, we derive provable, distributed control laws for stabilizing and changing the shape of a formation of vehicles in the plane. Tensegrity models define the desired, controlled, multi-vehicle system dynamics, where each node in the tensegrity structure maps to a vehicle and each interconnecting strut or cable in the structure maps to a virtual interconnection between vehicles. Our method provides a smooth map from any desired planar formation shape to a planar tensegrity structure. The stabilizing vehicle formation shape control laws are then given by the forces between nodes in the corresponding tensegrity model. The smooth map makes possible provably well behaved changes of formation shape over a prescribed time interval. A designed path in shape space is mapped to a path in the parametrized space of tensegrity structures and the vehicle formation tracks this path with forces derived from the time-varying tensegrity model. By means of examples, we illustrate the influence of design parameters on performance measures.