Qingke Tan

Necessary and sufficient conditions for average formation tracking of second-order multi-agent systems with multiple leaders☆

Abstract Average formation tracking problems for second-order multi-agent systems with multiple leaders and directed interaction topologies are studied, where the states of followers form a predefined time-varying formation while tracking the average state of the multiple leaders. An average formation tracking protocol is constructed using neighboring relative information, where only part of the followers which are named as well-informed ones are required to obtain the information of the multiple leaders. New properties of the Laplacian matrix are derived under the assumption that for each uninformed follower, there exists at least one directed path from a well-informed follower to it. Necessary and sufficient conditions for second-order multi-agent systems with multiple leaders to achieve average formation tracking are proposed by utilizing the properties of the Laplacian matrix. An approach to design the average formation tracking protocol is presented by solving an algebraic Riccati equation. The presented results can be applied to deal with the target enclosing problems, average tracking problems and consensus tracking problems for second-order multi-agent systems with one or multiple targets/leaders. An application example in multiple vehicles enclosing is provided to demonstrate the effectiveness of the theoretical results.

Active control method on flutter suppression of a high-aspect-ratio two-dimensional airfoil with a control surface

The structure of aircrafts airfoil is elastic and flexible. When the aircraft flies at a certain speed in the flow field, the couple-interaction of airfoils elastic deformation and aerodynamic force will cause its self-excited vibration with amplitude increase, and this phenomenon is called airfoils flutter. Such sharply divergent structural aeroelastic vibrations may threaten the flight safety seriously. This paper focuses on the problem of active flutter suppression of a typical high-aspect-ratio two-dimensional airfoil with a control surface. The control surface is driven by an actuator. First, a physical model of the high-aspect-ratio two-dimensional airfoil involving a three-DOF (degree-of-freedom) motion which includes the dynamic characteristics of the actuator is proposed. By analyzing the physical models differential equations of motion and the actuators transfer function, the state-space of the aeroelastic system which is composed of the high-aspect-ratio two-dimensional airfoil and the control surface with actuator is established. Then, on the basis of the state-space model, controllers respectively based on the optimal control theory and robust control theory are successfully designed. Finally, the simulation results indicate that all these designed controllers have an excellent performance on flutter suppression and they also can be able to improve the original systems flutter boundary speed. The contrastive analysis of controllers designed by different methods is also given at the end of this paper.

Circular formation tracking control for time-delayed second-order multi-agent systems with multiple leaders

In this paper, circular formation tracking control problems for time-delayed second-order multi-agent systems (MASs) with multiple leaders are studied, where the state of followers are designed to form a circular formation while tracking the average state of the multiple leaders. A circular formation tracking control protocol with time-varying delays is proposed. Sufficient conditions for time-delayed second-order MASs with multiple leaders to realize circular formation tracking are given. The presented results can be applied to target enclosing problem for multiple unmanned aerial vehicles (UAVs) with a group of targets and time-varying delays. Numerical examples on target enclosing are provided to demonstrate the feasibility of the theoretical results.

Weighted average consensus-based cubature Kalman filtering for mobile sensor networks with switching topologies

To deal with the distributed estimation for mobile sensor networks with switching topologies, an algorithm of the weighted average consensus-based cubature Kalman filtering is proposed by combining the advantages of the cubature Kalman filtering in information form and consensus algorithm. On the basis of the predecessors research work, the sufficient condition is presented for ensuring the weighted average consensus estimation in mobile sensor networks. Besides, the stability of the algorithm is analyzed for nonlinear systems with nonlinear state equation and nonlinear observation equation which are assumed to be continuously differentiable. Finally, the effectiveness of the proposed algorithm is evaluated on a target tracking case study with nonlinear motion equation and nonlinear observation equation.

Particle filter based on improved genetic algorithm resampling

For solving the problem of sample impoverishment in particle filter resampling, this paper proposes a particle filter based on improved genetic algorithm resampling combined with characteristics of selection operator, crossover operator and mutation operator in the genetic algorithm. In the improved genetic algorithm, we choose the importance weight of particles as the fitness value, select particles by utilizing simple resampling and elitist selection, and conduct crossover and mutation operation according to the changeable crossover probability and changeable mutation probability based on the degree of particle degeneracy. Simulation results demonstrate that the particle filter algorithm based on the improved genetic algorithm resampling could guarantee the validity of the particles and increase the diversity of the particles. This algorithm could improve the performance of the particle filter.