Bearing-based Formation Control Research Articles

Distributed Bearing-based Formation Control With Edge-triggered Observers

Distributed Bearing-based Formation Control With Edge-triggered Observers

Prescribed-Time Bearing-Based Formation Control of Underactuated ASVs Under External Disturbance

Prescribed-Time Bearing-Based Formation Control of Underactuated ASVs Under External Disturbance

Distributed finite-time bearing-based formation control for underactuated surface vessels with Levant differentiator

In this paper, a distributed bearing-based formation control scheme with finite-time convergency is proposed for multiple underactuated surface vessels (USVs). By virtue of the guide point-based model transformation method, the dimension of underactuated tracking error dynamics can be reduced from three to two. This allows us to convert the actuator model to a fully form that matches dimension-reduced tracking error dynamics. Further, to reduce the computation complexity, a finite-time recruited filter is designed according to first-order Levant differentiator. At meanwhile, auxiliary error compensation signals are introduced to address unknowns stemming from filter process and system dynamics. Since merely relative-distances and inner bearings are utilized in the proposed bearing-based formation approaches, the proposed control scheme provides a feasible solution to achieve formation control under body-fixed frame. Finally, theoretical analysis and numerical simulations are presented to demonstrate the efficacy.

Adaptive robust bearing-based formation control for multi-agent systems

The problem of bearing-based formation control with disturbance rejection has been studied by quite a few papers under various assumptions on the disturbances such as constant disturbances, trigonometric polynomial disturbances or bounded uniformly continuous disturbances with known bounds. In this paper, we further study the same problem with the disturbances being bounded piecewise continuous time functions. We first consider the case where the bounds of the disturbances are known. We show that the problem can be solved by a distributed static state feedback control law. Then we further consider the case where the bounds of the disturbances are unknown. We manage to solve this problem by introducing the adaptive control technique to deal with the unknown bounds of the disturbances. Our results include all the existing results on the bearing-based formation control with disturbance rejection as special cases. Moreover, we present a sufficient condition on the initial values of the closed-loop system for each case that prevents the collision.

Distributed bearing-based formation maneuver control of fixed-wing UAVs by finite-time orientation estimation

This paper investigates the bearing-based formation maneuver control problem for a group of fixed-wing unmanned aerial vehicles. Unlike the existing works that only steer UAV swarm to achieve a fixed geometric pattern, our objective is to enable UAV swarm to maneuver as a group such that the centroid, scale and orientation of the formation can be continuously changed. The underlying graph of UAV swarm is assumed to satisfy a leader-first-follower structure, and the desired formation maneuvering parameters are only accessible to the leader. To address such issue, a cascaded control scheme is proposed. Firstly, we propose a distributed quaternion-based observer for each follower to estimate the desired orientation of the formation in finite time. Secondly, a bearing-based formation control law is developed to achieve the maneuvering formation, in which an adaptive-gain finite-time disturbance observer is synthesized to reject the deformations which vary the bearing constraints. It is demonstrated that the closed-loop formation tracking error converges to zero exponentially. Comparative simulations are preformed to demonstrate the effectiveness of the proposed method.

Label-Free Formation Control of Multi-Agent Systems with Bearing-Based Self-Organizing Map Neural Network

This paper proposes a label-free bearing-based formation control method of multi-agent systems based on a self-organizing map (SOM) neural network. The Follower Henneberg Construction is defined to construct the interaction network of the multi-agent system. The position of each agent in the target formation is not preset, but determined by the consensus-based auction algorithm (CBAA) in the competition stage of the SOM to obtain optimal trajectories of agents. The proposed method drives agents to form the target formation by controlling the bearings between each agent and its neighbors. The effectiveness and robustness of the method are verified by simulating the formation control process in 2-dimensional and 3-dimensional Euclidean space.

Bearing-based formation control for multiple underactuated autonomous surface vehicles with flexible size scaling

Most existing formation control approaches for Autonomous surface vehicles (ASVs) focused on achieving rigid patterns with invariant inter-vehicle distance in open ocean environment. However, these methods cannot be applied to the cooperative missions on irregular inland waterway with changing width (such as rivers, canals and fjords), wherein the inter-vehicle distance should be continuously adjustable to respond to the environment dynamically. This paper proposes a bearing-based formation scaling control scheme for underactuated ASVs to achieve the desired patterns but with a flexible size scaling. By assuming that the fleet satisfies a leader–first-follower structure, the formation scaling parameters are accessible only to leaders, while each follower needs to maintain the bearing constraints to its neighboring ASVs without any knowledge of scale information. We respectively design distributed control laws for leaders and follower, and adaptive neural networks (NNs) are incorporated to approximate the dynamic uncertainties induced by parameter perturbations, external disturbances and input saturations. To improve the tracking performance, an auxiliary adaptive law is resorted to compensate the non-zero estimation error of NNs. Theoretical analysis demonstrates that the closed-loop scaling maneuver tracking and formation tracking errors converge to zero asymptotically. The comparative simulation results are presented to substantiate the effectiveness of the designed control method.

Bearing-Based Distributed Formation Control of Unmanned Aerial Vehicle Swarm by Quaternion-Based Attitude Synchronization in Three-Dimensional Space

Most of the recent research on distributed formation control of unmanned aerial vehicle (UAV) swarms is founded on position, distance, and displacement-based approaches; however, a very promising approach, i.e., bearing-based formation control, is still in its infancy and needs extensive research effort. In formation control problems of UAVs, Euler angles are mostly used for orientation calculation, but Euler angles are susceptible to singularities, limiting their use in practical applications. This paper proposed an effective method for time-varying velocity and orientation leader agents for distributed bearing-based formation control of quadcopter UAVs in three-dimensional space. It combines bearing-based formation control and quaternion-based attitude control using undirected graph topology between agents without the knowledge of global position and orientation. The performance validation of the control scheme was done with numerical simulations, which depicted that UAV formation achieved the desired geometric pattern, translation, scaling, and rotation in 3D space dynamically.

Bearing-based Formation Tracking of Multi-UAV System under Time-varying Directed Interaction

A problem of bearing-based formation control of a group of Unmanned Aerial Vehicles (UAVs) with directed and time-varying communication topology is considered. A subset of vehicles called “leaders” are remotely controlled to perform formation manoeuvres. The remaining vehicles, called “followers” use autonomous bearing-based control law for achieving the desired formation and maintaining it during the manoeuvres. Sufficient conditions for uniqueness of the formation in leader-follower configuration are analysed. For the time-varying manoeuvres of the leaders, the proposed control is shown to exponentially stabilize the formation. A switching time bound is presented that ensures the stability of the system with the proposed control under switching interaction topology. The results are validated with numerical simulations on a multi-vehicle system with directed and time-varying communication topologies.

Distributed bearing-based formation control of unmanned aerial vehicle swarm via global orientation estimation

Most existing formation control approaches for Unmanned Aerial Vehicle (UAV) swarm assume that global position and global coordinate frame are directly available for each agent. To extend the application domain, this paper proposes a distributed bearing-based formation control scheme, without any reliance on global position or global coordinate frame. The interactions among UAVs are described by a directed topology with two-leader structure. To address the issue of unavailable global coordinate frame, we first present a distributed orientation estimation law for each UAV to determine its orientation under the coordinate frame of the first leader. Based on the orientation estimation, we then design a bearing-based formation control law to globally asymptotically track target moving formations. Finally, simulation results are provided to validate the proposed method, which show that the translation, scale and orientation of the formation can be flexibly controlled via two leaders.

Distributed bearing-based formation control of networked thrust-propelled vehicles

In this paper, the distributed bearing-based formation control problem of networked thrust-propelled vehicles (TPVs) is addressed, in which both the constant and time-varying velocity leaders are considered, respectively. By introducing a reference acceleration and adaptive control scheme for the followers, the mass knowledge is not necessary in contrast to the existing works. Based on the designed reference accelerations, distributed adaptive control laws are proposed for the networked TPVs. Then the stabilization conditions are presented and an inner-bearing prescribed formation can be achieved. Under the proposed control laws, the leader-follower formation maneuver problem for networked TPVs with system uncertainties can be solved. Finally, simulation results are provided to demonstrate the effectiveness of the proposed control laws.

Specified-time bearing-based formation control of multi-agent systems via a dynamic gain approach

In this paper, the specified-time bearing-based formation control problem is investigated via a dynamic gain approach. Both the leader-follower and leaderless cases for single- and double-integral multi-agent systems are considered with bearing measurement, respectively. By considering the communication graph as bearing rigid, distributed bearing-based controllers with a time-varying gain are designed. By using time transformation method and Lyapunov stability theory, the close-loop systems under the proposed protocols can achieve the target formation within the specified time. Comparing with some existing results, the proposed approaches can make multi-agent systems converge to the desired formation within any preset time without dependence on the initial conditions or system parameters. Finally, some simulations and experiments are presented to demonstrate the effectiveness of the proposed algorithms.

Bearing-based formation control of networked robotic systems with parametric uncertainties

Abstract In this paper, the distributed bearing-based formation control problem for networked robotic systems with parametric uncertainties is investigated. Firstly, under the consideration that the task-space velocity is measurable, a reference control input is designed to achieve a bearing constrained target formation. For the unmeasurable task-space velocity case, an observer-based reference velocity scheme is proposed and only the local relative task-space position measurement is needed to achieve globally bearing-based formation stabilization. By designing a velocity feedback in proportional-integral reference velocity control scheme, at least two leaders can handle the leader–follower formation tracking problem, in which the followers do not need any global information. Finally, some simulation results are provided to demonstrate the effectiveness of the proposed control laws.

Bearing-Based Formation Control of A Group of Agents with Leader-First Follower Structure

This paper studies bearing-based formation control of a group of autonomous agents with the leader-first follower (LFF) structure in an arbitrary dimensional space. First, the bearing-based Henneberg construction and some properties of the LFF formation are introduced. Then, we propose and analyze bearing-only control laws that almost globally stabilize LFF formations to a desired formation. Further strategies to rotate and rescale the target formation are also discussed. Finally, simulation results are provided to support the analysis.

Translational and Scaling Formation Maneuver Control via a Bearing-Based Approach

This paper studies distributed maneuver control of multi-agent formations in arbitrary dimensions. The objective is to control the translation and scale of the formation while maintaining the desired formation pattern. Unlike conventional approaches where the target formation is defined by relative positions or distances, we propose a novel bearing-based approach where the target formation is defined by inter-neighbor bearings. Since the bearings are invariant to the translation and scale of the formation, the bearing-based approach provides a simple solution to the problem of translational and scaling formation maneuver control. Linear formation control laws for double-integrator dynamics are proposed and the global formation stability is analyzed. This paper also studies bearing-based formation control in the presence of practical problems including input disturbances, acceleration saturation, and collision avoidance. The theoretical results are illustrated with numerical simulations.