Distributed Event-Triggered Circular Formation Control for Multiple Anonymous Mobile Robots With Order Preservation and Obstacle Avoidance

Abstract

This paper investigates circular formation control problems for a group of anonymous mobile robots in the plane, where all robots can converge asymptotically to a predefined circular orbit around a fixed target point without collision, and maintain any desired relative distances from their neighbors. Given the limited resources for communication and computation of robots, a distributed event-triggered method is firstly designed to reduce dependence on resources in multi-robot systems, where the controller's action is determined by whether the norm of the event-trigger function exceeds zero through continuous sampling. And then, to further minimize communications costs, a self-triggered strategy is proposed, which only uses discrete states sampled and sent by neighboring robots at their event instants. Furthermore, for the two proposed control laws, a Lyapunov functional is constructed, which allows sufficient stability conditions to be obtained on the circular formation for multi-robot systems. And at the same time, the controllers are proved to exclude Zeno behavior. At last, numerical simulation of controlling uniform and non-uniform circular formations by two control methods are conducted. Simulation results show that the designed controller can control all mobile robots to form either a uniform circular formation or a non-uniform circular formation while maintaining any desired relative distances between robots and guaranteeing that there is no collision during the whole evolution. One of the essential features of the proposed control methods is that they reduce the update rates of controllers and the communication frequency between robots. And also, the spatial order of robots is also preserved throughout the evaluation of the system without collision.

A Survey on Techniques in the Circular Formation of Multi-Agent Systems

“…The bearing rigidity and ETC mechanism are applied in [209] to address the encirclement control problem of MAS around a moving target. Further, [210] addressed the ETC-based CFP for a group of anonymous mobile robots with restricted computational and communication abilities. Recently, a novel co-design combination of nonuniform quantization and ETC mechanism is designed in [211] to solve the ETC-based CFP.…”

Distributed control of mobile robots in an environment with static obstacles

“…This is of no surprise as the idea of deploying a decentralised group of robots, working in collaboration by distributing information, is very enticing and has many applications. Some of the most popular tasks for swarm robotics are: moving while preserving a formation [1][2][3], exploration and mapping of an unknown region [4][5][6][7], and foraging [8][9][10], where the robots have to find and transport objects to specific locations.…”

Distributed Time-Varying Output Formation Tracking Control for General Linear Multi-Agent Systems With Multiple Leaders and Relative Output-Feedback

“…A growing body of literature [1]- [3] shows that the significance of collaborative control cannot be ignored to achieve the requirement. Formation control, as one of the main research branches of collaborative control, has been widely used as a major approach to regulate relative coordinates among unmanned surface vehicles [4], mobile robots [5], unmanned aerial vehicles [6] and so on. A group of agents working together and maintaining the desired formation configuration is more efficient than a single agent when executing challenging missions such as rescue operations, reconnaissance, security patrol, and exploration.…”

“…Distributed TVSF control approaches in [15] and [16] are suitable for large-scale general linear MASs with switching undirected network and fixed directed network, respectively. In practical engineering applications, a MAS can be formed by multiple vehicles, such as mobile robots [5] and unmanned aerial vehicles [17], [18]. Position, velocity, attitude, and other unmeasured variables constitute the states of each vehicle.…”