Formation Maneuvering Control Research Articles

Adaptive estimator‐based formation maneuvering control of nonholonomic mobile robots

SummaryIn this paper, the formation maneuvering control problem for a group of nonholonomic mobile robots with the objective of having a desired formation shape described by distances between pairs of robots and an overall maneuvering velocity is studied. The desired maneuvering velocity, which can be constant or time‐varying, is only known to a set of agents. A control scheme consisting of an adaptive estimator and a modified gradient control law is proposed to solve this problem. The adaptive estimator is designed to estimate the desired maneuvering velocity in either constant or time‐varying situation. Utilizing the estimated velocity, a modified gradient control law is designed based on the nonholonomic kinematic model so that the objective is achieved. Local asymptotic convergence of the overall system is guaranteed by choosing appropriate control parameters. The effectiveness of the proposed control scheme is demonstrated through simulation results.

Distance-Based Formation Maneuvering of Non-Holonomic Wheeled Mobile Robot Multi-Agent System

In this paper, finite-time distance-based formation maneuvering control of a non-holonomic wheeled mobile robot multi-agent system in a leader-follower configuration is considered. The desired formation graph is assumed to be minimally and infinitesimally rigid, and only a subset of agents has access to the relative position and velocity of the leader. A distributed velocity estimator is employed by each agent to estimate the leader’s velocity and therefore the swarm velocity in finite-time. A finite-time formation maneuvering algorithm is presented and it is proved that drives the agents to the desired formation and tracks the leader’s velocity in finite-time. Moreover, it is demonstrated that both the velocity estimator and the controller can be implemented in the agents’ local coordinate frames. Simulations are provided to illustrate the effectiveness of the proposed algorithms.

Affine Formation Maneuver Control of Event-triggered Multi-agent Systems

An event-triggered affine formation maneuver control problem is studied in this work. The formations are invariant for any affine transformation. An event-triggered mechanism is proposed for the closed-loop system under which the controller updates and information broadcasting are generated only when it is necessary to maintain the system behavior. The practical convergence is guaranteed for the closed-loop system and Zeno behavior is excluded. Simulations are provided to verify the effectiveness of the method.

Output-Feedback Cooperative Formation Maneuvering of Autonomous Surface Vehicles With Connectivity Preservation and Collision Avoidance.

In this paper, a cooperative time-varying formation maneuvering problem with connectivity preservation and collision avoidance is investigated for a fleet of autonomous surface vehicles (ASVs) with position-heading measurements. Each vehicle is subject to unknown kinetics induced by internal model uncertainty and external disturbances. At first, a nonlinear state observer is used to recover the unmeasured linear velocity and yaw rate as well as unknown uncertainty and disturbances. Then, observer-based cooperative time-varying formation maneuvering control laws are designed based on artificial potential functions, nonlinear tracking differentiators, and a backstepping technique. The stability of closed-loop distributed formation control system is analyzed based on input-to-state stability and cascade stability. The salient features of the proposed method are as follows. First, cooperative time-varying formation maneuvering with the capability of connectivity preservation and collision avoidance can be achieved in the absence of velocity measurements. Second, the complexity of the cooperative time-varying formation maneuvering control laws is reduced without resorting to dynamic surface control. Third, the uncertainty and disturbance are actively rejected in the presence of position-heading measurements. Simulation results are given to substantiate the proposed output feedback control method for cooperative time-varying formation maneuvering of ASVs with connectivity preservation and collision avoidance.

Affine Formation Maneuver Control of Multiagent Systems

A multiagent formation control task usually consists of two subtasks. The first is to steer the agents to form a desired geometric pattern, and the second is to achieve desired collective maneuvers so that the centroid, orientation, scale, and other geometric parameters of the formation can be changed continuously. This paper proposes a novel affine formation maneuver control approach to achieve the two subtasks simultaneously. The proposed approach relies on stress matrices, which can be viewed as generalized graph Laplacian matrices with both positive and negative edge weights. The proposed control laws can track any target formation that is a time-varying affine transformation of a nominal configuration. The centroid, orientation, scales in different directions, and even geometric pattern of the formation can all be changed continuously. The desired formation maneuvers are only known by a small number of agents called leaders, and the rest of the agents called followers only need to follow the leaders. The proposed control laws are globally stable and do not require global reference frames if the required measurements can be measured in each agent's local reference frame.

Finite-Time Rigidity-Based Formation Maneuvering of Multiagent Systems Using Distributed Finite-Time Velocity Estimators.

In this paper, finite time rigidity-based formation maneuvering control of single integrator multiagent systems is considered. The target formation graph is assumed to be minimally and infinitesimally rigid, and the desired group velocity is considered to be available only to a subset of the agents. A distributed nonsmooth velocity estimator is used for each agent to estimate the desired group velocity in finite time. Using Lyapunov and input to state stability notions, a finite time distance-based formation maneuvering controller is presented and it is proved that by using the controller, agents converge to the target formation and track the desired group velocity in finite time. Furthermore, it is demonstrated that the designed controller is implementable in local coordinate frames of the agents. Simulation results are provided to show the effectiveness of the proposed control scheme.

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.