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 Unmanned Aerial Vehicles: Theories and Applications

Time-varying formation tracking analysis and design problems for second-order Multi-Agent systems with switching interaction topologies are studied, where the states of the followers form a predefined time-varying formation while tracking the state of the leader. A formation tracking protocol is constructed based on the relative information of the neighboring agents. Necessary and sufficient conditions for Multi-Agent systems with switching interaction topologies to achieve time-varying formation tracking are proposed together with the formation tracking feasibility constraint based on the graph theory. An approach to design the formation tracking protocol is proposed by solving an algebraic Riccati equation, and the stability of the proposed approach is proved using the common Lyapunov stability theory. The obtained results are applied to solve the target enclosing problem of a multiquadrotor unmanned aerial vehicle (UAV) system consisting of one leader (target) quadrotor UAV and three follower quadrotor UAVs. A numerical simulation and an outdoor experiment are presented to demonstrate the effectiveness of the theoretical results.

Time-Varying Formation Tracking for Second-Order Multi-Agent Systems Subjected to Switching Topologies With Application to Quadrotor Formation Flying

This paper addresses the distributed formation control problem of a networked multi-agent system (MAS) subject to limited communication resources. First, a dynamic event-triggered communication mechanism (DECM) is developed to schedule inter-agent communication such that some unnecessary data exchanges among agents can be reduced so as to achieve better resource efficiency. Different from most of the existing event-triggered communication mechanisms, wherein threshold parameters are fixed all the time, the threshold parameter in the developed event triggering condition is dynamically adjustable in accordance with a dynamic rule. It is numerically shown that the proposed DECM can achieve a better tradeoff between reducing inter-agent communication frequency and preserving an expected formation than some existing ones. Second, an event-triggered formation protocol is delicately proposed by using only locally triggered sampled data in a distributed manner. Based on the formation protocol, it is shown that the state formation control problem is cast into an asymptotic stability problem of a reduced-order closed-loop system. Then, criteria for designing desired formation protocol and communication mechanism are derived. Finally, the effectiveness and advantages of the proposed approach are demonstrated through a comparative study in multirobot formation control.

Distributed Formation Control of Networked Multi-Agent Systems Using a Dynamic Event-Triggered Communication Mechanism

This paper studies the observer-based leader-following consensus of a linear multiagent system on switching networks, in which the input of each agent is subject to saturation. Based on a low-gain output feedback method, distributed consensus protocols are developed. Under the assumptions that the networks are connected or jointly connected and that each agent is asymptotically null controllable with bounded controls and detectable, semiglobal observer-based leader-following consensus of the multiagent system can be reached on switching networks. A numerical example is presented to illustrate the theoretical results.

Semiglobal Observer-Based Leader-Following Consensus With Input Saturation

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

In this paper, we consider the problem of decentralized cohesive motion control of a formation of autonomous vehicles or robots moving in three dimensions, where the formation is required to move from its initial setting (defined by the positions of the agents in the formation) to a final desired setting and, during this motion, maintain its formation geometry defined by the initial distances between the agent pairs We propose a distributed control scheme to solve this problem utilizing the notions of graph rigidity and persistence as well as techniques of virtual target tracking and smooth switching The distributed control scheme is developed by modeling the agent kinematics as single-velocity integrator; nevertheless, extension to the cases with practical kinematic and dynamic models of fixed-wing autonomous aerial vehicles and quadrotors is discussed In this context, we examine the maintenance of geometric formation of a swarm of autonomous flight vehicles The developed coordination and control schemes are verified via a number of simulations

Distributed Cohesive Motion Control of Flight Vehicle Formations

One of the challenges for manned-unmanned air vehicles flying in joint airspace is the need to develop customized but scalable algorithms and hardware that will allow safe and efficient operations. In this work, we present the design of a bus-backboned UAV microavionics system and the hardware-in-the-loop integration of this unit within a joint flight network simulator. The microavionics system is structured around the Controller Area Network and Ethernet bus data backbone. The system is designed to be cross-compatible across our experimental mini-helicopters, aircrafts and ground vehicles, and it is tailored to allow autonomous navigation and control for a variety of different research test cases. The expandable architecture allows not only scalability, but also flexibility to test manned-unmanned fleet cooperative algorithm designs at both hardware and software layer deployed on bus integrated flight management computers. The flight simulator is used for joint simulation of virtual manned and unmanned vehicles within a common airspace. This allows extensive hardware-in-the-loop testing capability of customized devices and algorithms in realistic test cases that require manned and unmanned vehicle coordinated flight trajectory planning.

http://cal.uubf.itu.edu.tr/~inalhan/Inalhan_Publications/JINT08.pdf

Design and Hardware-in-the-Loop Integration of a UAV Microavionics System in a Manned---Unmanned Joint Airspace Flight Network Simulator

Designing 3-DOF Hardware-In-The-Loop Test Platform Controlling Multirotor Vehicles

In this paper, we focus on cooperative adaptive cruise control of ground vehicles and platoon stability in daily traffic. The general adaptive cruise control (ACC) structure and different cooperative adaptive cruise control (CACC) approaches are discussed for highway platooning, considering case studies for a Grand Cooperative Driving Challenge (GCDC) program the authors involved in. The hardware design and the low level control strategy for braking, throttle and gearshift actuators for these case studies are presented. Finally, the performance of a PD based CACC algorithm used in GCDC is analyzed.

Design of string stable adaptive cruise controllers for highway and urban missions

In this work, we present a micro-avionics system structured around the controller area network (CAN) bus data backbone. The system is designed to be cross-compatible across our experimental mini-helicopters and ground vehicles, and it is tailored to allow autonomous navigation and control for a variety of different research test cases. The expandable architecture deploys a hybrid selection of COTS Motorola (MPC555) and Arm processor boards (LPC2294), each with different operating systems and coding techniques (such as rapid algorithmic prototyping using automatic code generation via Matlab/Real Time Workshop Embedded Target). The micro-avionics system employs a complete sensor suite that provides real-time position, orientation and associated time-rate information. As a part of the on-going fleet autonomy experiments, we present the design of a novel wireless SmartCan node. This wireless node allows seamless CAN Bus access of low-level sensor and operational data of other vehicles within close proximity.

Ismail Bayezit

Papers

Distributed Cohesive Motion Control of Flight Vehicle Formations

Design and Hardware-in-the-Loop Integration of a UAV Microavionics System in a Manned---Unmanned Joint Airspace Flight Network Simulator

Designing 3-DOF Hardware-In-The-Loop Test Platform Controlling Multirotor Vehicles

Design of string stable adaptive cruise controllers for highway and urban missions

Development of a Cross-Compatible Micro-Avionics System for Aerorobotics