Zongying Shi

Time-Varying Formation Control for Unmanned Aerial Vehicles: Theories and Applications

Formation control analysis and design problems for unmanned aerial vehicle (UAV) swarm systems to achieve time-varying formations are investigated. To achieve predefined time-varying formations, formation protocols are presented for UAV swarm systems first, where the velocities of UAVs can be different when achieving formations. Then, consensus-based approaches are applied to deal with the time-varying formation control problems for UAV swarm systems. Necessary and sufficient conditions for UAV swarm systems to achieve time-varying formations are proposed. An explicit expression of the time-varying formation center function is derived. In addition, a procedure to design the protocol for UAV swarm systems to achieve time-varying formations is given. Finally, a quadrotor formation platform, which consists of five quadrotors is introduced. Theoretical results obtained in this brief are validated on the quardrotor formation platform, and outdoor experimental results are presented.

Output consensus analysis and design for high-order linear swarm systems: Partial stability method

Output consensus analysis and design problems for high-order linear time-invariant swarm systems with directed interaction topologies are investigated. Firstly, as foundations of our approaches, several conclusions about partial stability are given. Then, two subspaces of the output space of swarm systems, namely an output consensus subspace and a complement output consensus subspace, are introduced. Based on output projection onto the two subspaces and partial stability, necessary and/or sufficient conditions for output consensus and limited-control-energy consensus are proposed respectively, an explicit expression of the output consensus function is presented based on the different contributions of initial states of agents and protocols, and an approach independent of the number of agents is shown to determine the gain matrices of output consensus protocols. Finally, a numerical example is given to demonstrate the theoretical results.

Delay-dependent admissible consensualization for singular time-delayed swarm systems ☆

Abstract Admissible consensus analysis and design problems for high-order linear time-invariant singular swarm systems with time delays are investigated. Firstly, by state decomposition, the admissible consensus problem is transformed into admissible problems of multiple singular subsystems with lower dimensions. Then, linear matrix inequality (LMI) criteria for admissible consensualization are presented, which only involve eight LMI constraints independent of the number of agents. Moreover, an explicit expression of the consensus function which is independent of time delays is presented, and the impacts of protocol states and interaction topologies on the consensus function are revealed. Finally, a numerical example is given to illustrate the effectiveness of theoretical results.

Robust Tracking Control of a Quadrotor Helicopter

In this paper, a robust tracking control method for automatic take-off, trajectory tracking, and landing of a quadrotor helicopter is presented. The designed controller includes two parts: a position controller and an attitude controller. The position controller is designed by the static feedback control method to track the desired trajectory of the altitude and produce the desired angles for pitch and roll angles. By combining the proportional-derivative (PD) control method and the robust compensating technique, the attitude controller is designed to track the desired pitch and roll angles and stabilize the yaw angle. It is proven that the attitude tracking error of each channel can converge to the given neighborhood of the origin ultimately. Experimental results demonstrate the effectiveness of the designed control method.

Practical consensus for high-order linear time-invariant swarm systems with interaction uncertainties, time-varying delays and external disturbances

Practical consensus problems for general high-order linear time-invariant swarm systems with interaction uncertainties and time-varying external disturbances on directed graphs are investigated in this article. A dynamic consensus protocol with non-uniform time-varying delays is adopted to deal with the practical consensus problem. Using state space decomposition, practical consensus problems of a swarm system are converted into stability problems of a disagreement subsystem. Based on the Lyapunov–Krasovskii functional approach and the linear matrix inequality technique, sufficient conditions for swarm systems to achieve practical consensus are proposed where the time-varying external disturbance can be in L 2 or L ∞. Numerical simulations are presented to demonstrate theoretical results.

Robust Flight Control of Quadrotor Unmanned Air Vehicles

For quadrotor unmanned air vehicles(UAVs) flight control problem,a robust controller design approach is presented.The controller consists of two parts: an inner-loop attitude controller and an outer-loop position controller.The attitude controller is designed with robust control based on signal compensation.The position controller is realized with classical PD method.It is applied to a quadrotor UAV developed in our laboratory to realize indoor hovering.Experimental results demonstrate the effectiveness of this control approach.

Output consensus for high-order linear time-invariant swarm systems

Output consensus analysis and design problems of high-order linear time-invariant swarm systems are investigated. First, an output consensus subspace and a complement output consensus subspace are introduced. By output projection onto the two subspaces and the partial stability theory, a necessary and sufficient condition for output consensus is presented, and an explicit expression of the output consensus function, which is jointly determined by the interaction topology and initial states of all agents, is given. Especially, it is shown that the output consensus function is completely determined by initial states of all agents if the interaction topology is balanced. Then, an approach to determine gain matrices in consensus protocols of swarm systems is proposed, which has less calculation complexity. Finally, a numerical example is shown to demonstrate theoretical results.

Output containment control for swarm systems with general linear dynamics: A dynamic output feedback approach ☆

Abstract Output containment control problems for high-order linear time-invariant swarm systems under directed interaction topologies are investigated using a dynamic output feedback approach. Firstly, to propel the outputs of followers to converge to the convex hull formed by the outputs of leaders, a dynamic output containment protocol is presented. Then necessary and sufficient conditions for swarm systems to achieve output containment are proposed. To ensure the scalability of the criteria, a sufficient condition which only includes two linear matrix inequality constraints independent of the number of agents is further presented. Moreover, an approach independent of the number of agents is proposed to determine the gain matrices in the dynamic output containment protocols. Finally, numerical simulations are presented to demonstrate theoretical results.

Time-varying output formation control for high-order linear time-invariant swarm systems

Formation control of swarm systems has gained considerable attention from scientific communities due to its potential applications in various areas. In practical applications, the dynamics of each agent may be of high order and only the outputs of all agents are required to achieve time-varying formations. Therefore, this paper focuses on time-varying output formation control problems for high-order linear time-invariant swarm systems with directed interaction topologies. A general output formation protocol is proposed based on the relative outputs of neighboring agents. Necessary and sufficient conditions for swarm systems to achieve time-varying output formations are presented using a consensus based approach. An explicit expression of the output formation reference function is given. For a swarm system, whether or not a desired output formation is feasible is a crucial problem. Based on partial stability theory, necessary and sufficient conditions for output formation feasibility are derived. Approaches to expand the feasible time-varying output formation set and an algorithm to design the protocol for swarm systems to achieve time-varying output formation are presented respectively. Finally, theoretical results are demonstrated by numerical simulations.

Gait Planning Of Quadruped Robot Based On Third-Order Spline Interpolation

This paper presented a brief description for the gait planning of quadruped robot named Aibo ERS-7 which is a standard platform in the RoboCup 4-legged league. We approach a spline shaped locus to reduce the dimension of the parameter optimizing space and solve the problem of the significant bias between the planned locus and the real one. The result shows that the spline shaped locus is effective in finding the optimized locus shape in a short time. Finally, the robot achieves a gait faster than any previously known learned gait for Aibo