Time-varying Formation Control Research Articles

Time-varying formation control for double-integrator multi-agent systems with jointly connected topologies

ABSTRACTTime-varying formation analysis and design problems for double-integrator multi-agent systems with jointly connected topologies are investigated. Different from the previous work on formation control, in this paper, the formation is specified by time-varying piecewise continuously differentiable vectors and the topology can be disconnected at any time instant. First, a distributed formation control protocol is constructed using local neighbour-to-neighbour information. In the case where the switching topology is jointly connected, necessary and sufficient conditions for double-integrator multi-agent systems to achieve time-varying formations are proposed, where the formation feasibility constraint is also derived. To describe the macroscopic movement of the whole formation, explicit expressions of the formation reference are presented, the motion modes of which can be partially assigned. Moreover, an approach to design the formation control protocol is given, which is fully distributed and requires no global information about the topology. Finally, the obtained theoretical results are applied to deal with the time-varying formation control problems of multi-vehicle systems.

Time-varying formation control for unmanned aerial vehicles with switching interaction topologies

Time-varying formation control problems for unmanned aerial vehicle (UAV) swarm systems with switching interaction topologies are studied. Necessary and sufficient conditions for UAV swarm systems with switching interaction topologies to achieve predefined time-varying formations are proposed. Based on the common Lyapunov functional approach and algebraic Riccati equation technique, an approach to design the formation protocol is presented. An explicit expression of the formation reference function is derived to describe the macroscopic movement of the whole UAV formation. A quadrotor formation platform consisting of four quadrotors is introduced. Outdoor experiments are performed to demonstrate the effectiveness of the theoretical results.

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.

Time‐varying formation control for high‐order linear swarm systems with switching interaction topologies

Time-varying formation control problems for high-order linear time-invariant swarm systems with switching interaction topologies are investigated. A general formation control protocol is proposed firstly. Then using a consensus based approach, necessary and sufficient conditions for swarm systems with switching interaction topologies to achieve a given time-varying formation are presented. An explicit expression of the time-varying formation reference function is given. It is revealed that the switching interaction topologies have no effect on the formation reference function and the motion modes of the formation reference can be specified. Furthermore, necessary and sufficient conditions for formation feasibility are presented. An approach to expand the feasible formation set is given and an algorithm to design the protocol for swarm systems with switching interaction topologies to achieve time-varying formations is provided. Finally, numerical simulations are presented to demonstrate theoretical results.

Formation Control for High-Order Linear Time-Invariant Multiagent Systems With Time Delays

Formation control problems for high-order linear time-invariant multiagent systems with time delays are investigated. First, a general time-varying formation control protocol is proposed. Then, based on consensus approaches, necessary and sufficient conditions for multiagent systems to achieve a given time-varying formation are presented. An explicit expression of the time-varying formation reference function is also given. It is shown that the motion modes of the formation reference can be specified. Furthermore, necessary and sufficient conditions for formation feasibility are proposed. An approach to expand the feasible formation set and an algorithm to design the protocol for multiagent systems to achieve time-varying formations are provided, respectively. Finally, numerical simulations are presented to demonstrate theoretical results.

Time-varying formation control of a collaborative heterogeneous multi agent system

In this paper, coherent formation control of a multi-agent system in the presence of time-varying formation is studied. For special application of rescue and surveillance, a set of agents, consisting of unmanned aerial vehicles (UAVs) and unmanned ground vehicles (UGVs) are considered. Due to different degrees of freedom of the UAVs and the UGVs, the collaboration between the agents confronts many problems. A Lyapunov based controller is presented to stabilize the swarming and lead the system to a rigid formation using decentralized control approach. In the proposed control signal of each agent, a signal of the neighbors’ error is considered to cope with variation in performance and to provide synchronization, which means that the state error of the agents converges to zero nearly at the same time. The decentralized approach provides reliability of the performance in unknown environment, since the controller of each agent is designed based on local knowledge. This algorithm is evaluated in simulation and the results approve the accepted performance of the proposed approach.

Decentralized time-varying formation control for multi-robot systems

In this paper, a distributed controller–observer schema for tracking control of the centroid and of the relative formation of a multi-robot system with first-order dynamics is presented. Each robot of the team uses a distributed observer to estimate the overall system state and a motion control strategy for tracking control of time-varying centroid and formation. Proof of the overall convergence of the controller–observer schema for different kinds of connection topologies, as well as for the cases of unsaturated and saturated control inputs is presented. In particular, the solution is proven to work in the case of strongly connected non-switching topologies and in the case of balanced strongly connected switching topologies. In order to complete the work, the approach is validated by experimental tests with a team of five wheeled mobile robots.

Time varying Formation Control Using Differential Game Approach

AbstractThis paper deals with time varying formation control of mobile robots i.e. the formation can change during the mission. To achieve this goal differential game approach is proposed to control the formation. A time varying incidence matrix is defined to determine the interconnection between robots. An open loop Nash equilibrium solution is employed to satisfy the defined cost function for each robot (the players in differential game) and control the formation. The convergence of the proposed approach to the desired formation is studied. By minor modifications, the introduced approach can be applied for a wide range of fully decentralized to leader follower formation. The effectiveness of the proposed method is verified by simulations.