Formation Control Of Mobile Robots Research Articles

Adaptive Vision-Based Leader–Follower Formation Control of Mobile Robots

This paper focuses on the problem of vision-based leader–follower formation control of mobile robots. The proposed adaptive controller only requires the image information from an uncalibrated perspective camera mounted at any position and orientation (attitude) on the follower robot. Furthermore, the approach does not depend on the relative position measurement and communication between the leader and follower. First, a new real-time observer is developed to estimate the unknown intrinsic and extrinsic camera parameters as well as the unknown coefficients of the plane where the feature point moves relative to the camera frame. Second, the Lyapunov method is employed to prove the stability of the closed-loop system, where it is shown that convergence of the image error is guaranteed. Finally, the performance of the approach is demonstrated through physical experiments and experimental results.

Formation Control of Agricultural Mobile Robots: A Bidirectional Weighted Constraints Approach

AbstractThis paper focuses on the formation control of several mobile robots in off‐road conditions. A control strategy based on bidirectional referencing is proposed, where each robot combines a velocity control w.r.t. the immediate preceding neighbor with a control w.r.t. the immediate following neighbor. Two virtual leaders, respectively, at the head and at the tail of the fleet, are propelling the fleet at the desired velocity. The fleet stability is investigated using Lyapunov techniques, pending on combination coefficients. The stability is theoretically proven for constant coefficients as weights of the respective velocity controls and tested through simulations and full‐scale experiments. It is shown that this control strategy permits us to reduce the error propagation problem often encountered in formation control, while limiting the communication problems of the global strategies. As a result, a stable formation control architecture is defined, which requires each vehicle to be refereed only to two other robots. This limited communication need is particularly interesting for agricultural operations. The proposed approach is implemented in this paper on agricultural tractors.

Distributed tracking control of uncertain mechanical systems with velocity constraints

SummaryThis paper considers the leader‐following control problem of multiple mechanical systems with uncertainty and velocity constraints. So as to deal with the velocity constraints, a reduction procedure is applied to transform the model of each system to a cascaded system. With the aid of the cascade structure of each system and the properties of linear time‐varying systems, distributed robust feedback controllers are proposed such that the state of each follower system asymptotically converges to the state of a leader system with the aid of neighbors' information. So as to reduce the cost of the communication between systems, an event‐triggered leader‐following control problem is also considered, and event‐triggered distributed controllers are proposed. As an application of the proposed results, formation control of wheeled mobile robots is considered, and distributed controllers are obtained with the aid of the results in Theorems 1 and 2. Simulation results show the effectiveness of the proposed results. Copyright © 2017 John Wiley & Sons, Ltd.

Leader-follower Formation Control of Mobile Robots with Sliding Mode

Leader-follower Formation Control of Mobile Robots with Sliding Mode

駆動源に飽和を有する移動ロボットのフォーメーション制御

駆動源に飽和を有する移動ロボットのフォーメーション制御

Formation Control of Mobile Robots Using Distributed Controller With Sampled-Data and Communication Delays

This brief presents a synchronous formation control approach using distributed controller with sampled-data and communication delay. The local information of each robot is sampled first, and then transmitted to its coupling robots through a network with communication delays, i.e., the information exchanged between coupling robots is the sampled-data with communication delays. The distributed formation controller is designed by using the synchronization approach, which enables mobile robots to maintain time-varying formations while performing a group task in a synchronous manner. A sufficient condition for formation control that can guarantee the exponential convergence of both the position errors and the synchronization errors is obtained by using the Lyapunov approach. Based on the proposed sufficient condition, an upper bound of the sampling period and the communication delay that guarantees mobile robots to converge to the desired formations can be easily obtained. Finally, the effectiveness of the proposed method is demonstrated by simulations and real experiments.

Distributed Finite-Time Cooperative Control of Multiple High-Order Nonholonomic Mobile Robots.

The consensus problem of multiple nonholonomic mobile robots in the form of high-order chained structure is considered in this paper. Based on the model features and the finite-time control technique, a finite-time cooperative controller is explicitly constructed which guarantees that the states consensus is achieved in a finite time. As an application of the proposed results, finite-time formation control of multiple wheeled mobile robots is studied and a finite-time formation control algorithm is proposed. To show effectiveness of the proposed approach, a simulation example is given.

Flexible Formation of Multiple Car-like Robots with respect to a Dynamic Environment

This paper attempts to give a perspective on decentralized formation control of multiple car-like mobile robots using local information and formation changes in a dynamic environment having several obstacles. In addition, for every mobile robot, it takes physical dimensions, mass, moment of inertia, movement constraints and saturation of actuators into account. This study makes use of Input/output feedback linearization method to control each robot. Hence, hierarchical leader follower based algorithm is employed to control the group formation. To avoid collision between robots and obstacles, and between robots each other’s, local artificial potential fields are addressed. The group can change formation with respect to obstacles in the environment. Finally, simulation results of seven individual robots formation are presented to show the performance of the proposed control system.

Distributed Multirobot Formation and Tracking Control in Cluttered Environments

In this article, we propose formation control of nonholonomic mobile robots avoiding obstacles in a distributed manner for cluttered environments. The introduction of a virtual robot restructures the formation control problem into a tracking control problem between the virtual reference robot and follower robots. A novel obstacle avoidance approach is proposed based upon the scaling of whole (partial) formation corresponding to a centralized (distributed) framework. For the distributed environment with limited communication, our approach utilized proportional-integral average consensus estimators, whereby information from each robot diffuses through the communication network. The theoretical contribution is to determine the time constant involved in the diffusion process, which can affect overall system performance. The asymptotic convergence of follower robots to the position and orientation of the reference robot is ensured using the Lyapunov function. The new technique is tested with complete, limited, and no information availability. Several simulation results are provided that demonstrate the formation control and obstacle avoidance for multirobots using the proposed scheme.

Distributed consensus-based formation control for nonholonomic wheeled mobile robots using adaptive neural network

This paper investigates the distributed formation control problem for multiple nonholonomic wheeled mobile robots. A variable transformation is first proposed to convert the formation control problem into a state consensus problem. Then, when the dynamics of the mobile robots are considered, the distributed kinematic controllers and neural network torque controllers are derived for each robot such that a group of nonholonomic mobile robots asymptotically converge to a desired geometric pattern along the specified reference trajectory. The specified reference trajectory is assumed to be the trajectory of a virtual leader whose information is available to only a subset of the followers. Also the followers are assumed to have only local interaction. Moreover, the neural network torque controllers proposed in this work can tackle the dynamics of robots with unmodeled bounded disturbances and unstructured unmodeled dynamics. Some sufficient conditions are derived for accomplish the asymptotically stability of the systems based on algebraic graph theory, matrix theory, and Lyapunov control approach. Finally, simulation examples illustrate the effectiveness of the proposed controllers.

Cooperative formation control of autonomous underwater vehicles: An overview

Formation control is a cooperative control concept in which multiple autonomous underwater mobile robots are deployed for a group motion and/or control mission. This paper presents a brief review on various cooperative search and formation control strategies for multiple autonomous underwater vehicles (AUV) based on literature reported till date. Various cooperative and formation control schemes for collecting huge amount of data based on formation regulation control and formation tracking control are discussed. To address the challenge of detecting AUV failure in the fleet, communication issues, collision and obstacle avoidance are also taken into attention. Stability analysis of the feasible formation is also presented. This paper may be intended to serve as a convenient reference for the further research on formation control of multiple underwater mobile robots.

A General Purpose Network-Oriented Fault-Diagnose Control Architecture for MMR

WSN technology has strong advantages in the facet of environmental perception; node localization and path selection. The WSN technology combining with Multi Mobile Robots (MMR)can gain the ability of its self-planning, self-organization and self-adaption under the complex environment situation. The engineering record shows that the formation control of multi mobile robots is easily broken down. Even if a careful created robot formation at the great cost of manpower and material resources, it is possible breaking down when facing with unknown and complex environment. Recently, the traditional mobile robots formation also facing fault tolerance problem as well, such problems as low coupling, bad robustness and agreement diversification, especially hard to remedy the trouble when occurring the communication breakdown or damage. While WSN networks conducts a research on fault tolerant techniques, robots will show their advantages over localization, distance measuring, fault diagnosis, breakdown maintenance and formation recovery. Robots are installed WSN sensor node can perceive location between nodes by using this algorithm, the paper will proposing an algorithm based on WSN-MMR fault diagnosis through comparing the data perceived by neighbor nodes. It can ensure that the checked node situation and spread the state to other neighboring nodes in the networks. The algorithm can realize the fault diagnosis of the nodes and have a good performance, its feasibility and effectiveness can be tested.

Formation control of networked mobile robots with guaranteed obstacle and collision avoidance — ERRATUM

In the original version of this paper the email of the corresponding author, Reza Mahboobi Esfanjani, was given incorrectly. The correct email is mahboobi@sut.ac.ir.The publisher apologises for this error.

Tracking and Formation Control of Leader-Follower Cooperative Mobile Robots Based on Trilateration Data

This research deals with formation control of swarm robot based on changing of robot’s relative positional data. A follow the leader movement with simple triangle formation case is applied with three robots; a leader with two followers. Trilateration method is used as a method of determining the position of the leader robot from the follower robots using the distance to the reference point (local positioning). Follower robots are designed to follow every movement of the leader on a formation position. The controller is designed to maintain the formation position of the follower robots relatively to the leader. As a uniqueness, a relative positional control method by using bearing angle and distance error is proposed instead of the common Cartesian positional error control. From the experiment which conducted in maximum distance between the robots,it was obtained a maximum error approximately 56%. The follower robots are able to follow any changes in motion of the robot leader with average distance error of 36%.Keywords: Cooperative mobile robot, formation control, trilateration, follow the leader

Formation control of networked mobile robots with guaranteed obstacle and collision avoidance

SUMMARYThis note presents a novel method to design a controller for the formation of networked mobile robots, where the communication between the members of the group is affected by variable time-delay. The control objective is twofold: to maintain the formation during the motion along a desired path and guarantee no collisions with obstacles or adjacent robots. Initially, an innovative dynamical model is formulated for the system; afterwards, the notion of model predictive control is employed to ensure collision avoidance with guaranteed stability. Simulation results are provided to demonstrate the applicability and effectiveness of the suggested method.

Leader–Follower Formation and Tracking Control of Mobile Robots Along Straight Paths

We address the problem of tracking control of multiple mobile robots advancing in formation along straight-line paths. We use a leader–follower approach, and hence, we assume that only one swarm leader robot has the information of the reference trajectory. Then, each robot receives information from one intermediary leader only. Therefore, the communications graph forms a simple spanning directed tree. As the existence of a spanning tree is necessary to achieve consensus, it is the minimal configuration possible to achieve the formation-tracking objective. From a technological viewpoint, this has a direct impact on the simplicity of its implementation; e.g., less sensors are needed. Our controllers are partially linear time-varying with a simple added nonlinearity satisfying a property of persistency of excitation, tailored for nonlinear systems. Structurally speaking, the controllers are designed with the aim of separating the tasks of position-tracking and orientation. Our main results ensure the uniform global asymptotic stabilization of the closed-loop system, and hence, they imply robustness with respect to perturbations. All these aspects make our approach highly attractive in diverse application domains of vehicles’ formations such as factory settings.

Neural network-based finite horizon optimal adaptive consensus control of mobile robot formations

Summary In this paper, a novel NN-based optimal adaptive consensus-based formation control scheme over finite horizon is presented for networked mobile robots or agents in the presence of uncertain robot/agent dynamics. The uncertain robot formation dynamics are approximated online by using an NN-based identifier and a suitable weight tuning law. In addition, a novel time-varying value function is derived by using the augmented error vector, which consists of the regulation and consensus-based formation errors of each robot. By using the value function approximation and the identified dynamics, the near optimal control input over finite horizon is derived. This finite horizon optimal control leads to a time-varying value function, which becomes the solution of the Hamilton–Jacobi–Bellman equation, and control input is approximated by a second NN with time-varying activation function. A novel weight update law for the NN value function is developed to tune the value function, satisfy the terminal constraint, and relax an initial admissible controller requirement. The Lyapunov stability method is utilized to demonstrate the consensus of the overall formation. Finally, simulation results are given to verify theoretical claims. Copyright © 2015 John Wiley & Sons, Ltd.

적응 PID 제어기를 이용한 이동로봇의 군집제어

In this paper, we strengthen the advantages of a simple PID controller as a study on the formation control of mobile robots and propose an adaptive PID controller with robust performance at the dynamics characteristics of following robot. Simulation studies show that the adaptive PID controller has better keeping constant distance and angle such as tracking performance of following robot for the formation control than a conventional PID controller. This is the proposed adaptive PID controller to change the gains is found to represent the best performance. This is able to verify that the performance of the proposed adaptive PID controller is excellent.

Finite-time consensus of multiple nonholonomic chained-form systems based on recursive distributed observer

The consensus tracking problem of multiple nonholonomic high-order chained-form systems is considered in this paper. A finite-time observer-based distributed control strategy is proposed. At the first step, a distributed finite-time convergent observer is proposed for each agent to estimate the leader’s state in a finite time. Then, a finite-time tracking controller is designed to track the estimated state and the leader’s attitude in a finite time. As an application of the proposed results, finite-time formation control of multiple wheeled mobile robots is studied and a finite-time formation control algorithm is proposed. To show effectiveness of the proposed approach, a simulation example is given.

Adaptive distributed formation control for multiple nonholonomic wheeled mobile robots

This paper investigates the adaptive distributed formation control problem for multiple nonholonomic wheeled mobile robots. First, the formation control problem is converted into a state consensus problem by the aid of a variable transformation. Then, distributed kinematic controllers and adaptive dynamic controllers are developed for each robot such that a group of nonholonomic mobile robots asymptotically converge to a desired geometric pattern with its centroid moving along the specified reference trajectory. The specified reference trajectory is assumed to be the trajectory of a virtual leader whose information is available to only a subset of the followers. Also the followers are assumed to have only local interaction. Some sufficient conditions are derived for accomplishing the asymptotically stability of the systems based on algebraic graph theory, matrix theory, and Lyapunov control approach. Finally, simulation examples illustrate the effectiveness of the proposed controllers.