Formation Control of Mobile Robots Using a Beacon-Based Algorithm with Alternating Node Activation

This paper presents a leader-follower formation control of multiple mobile robots by position-based method using a fisheye camera. A fisheye camera has a wide field of view and recognizes a wide range of objects. In this paper, the fisheye camera is first modeled on spherical coordinates and then a position estimation technique is proposed by using an AR marker based on the spherical model. This paper furthermore presents a method for estimating the velocity of a leader robot based on a disturbance observer using the obtained position information. The proposed techniques are combined with a formation control based on the virtual structure. In this paper, the formation controller and velocity estimator can be designed independently, and the stability analysis of the total system is performed by using Lyapunov theorem. The effectiveness of the proposed method is demonstrated by simulation and experiments using two real mobile robots.

This paper presents a formation control of mobile robots with a large obstacle avoidance. The mobile robots considered in this paper have multiple sonars which are used for not only constructing formation but also avoiding obstacle. The novel modules overcoming the drawbacks of the previous navigation algorithm [6] are introduced to accomplish the obstacle avoidance and formation control. The effectiveness of the proposed techniques are demonstrated by an experiment using three mobile robots.

This paper presents the robustness in formation control of multiple mobile robots using leader-follower method. The uncertainty considered is the measured error which is included in the relative state. The robust stability conditions against the relative state error are derived by Lyapunov’s stability theory (direct method). We also obtain the formation steady-state deviation when formation stability is ensured. The formation control environment is constructed on Simulink. The validity of the stability condition and the steady-state deviation is demonstrated by numerical simulation. It is seen that the L-F method provides a robust control law against the relative state error although large formation steady-state deviation is occurred in some cases.

In this chapter, formation control of mobile robots with nonlinear models is considered. Two controllers are proposed with the aid of the dynamic feedback linearization technique, the time-scaling technique and properties of Laplacian matrix. The proposed controllers ensure the group of mobile robots to move in a desired formation. Existing results in formation control using graph theoretical methods are extended to nonlinear systems of high dimensions. Simulation results show the effectiveness of the proposed controllers.

A constructive method is presented to design cooperative controllers that force a group of N mobile robots to achieve a particular formation in terms of shape and orientation while avoiding collisions between themselves. The control development is based on new local potential functions, which attain the minimum value when the desired formation is achieved, and are equal to infinity when a collision occurs. The proposed controller development is also extended to formation control of nonholonomic mobile robots.

This paper considers the formation control of nonholonomic mobile robots. The formation problem is converted to the error model based on the leader-follower structure. A sliding mode controller, which is proved to be globally finite-time stable by Lyapunov stability theory, is presented in this study. In addition, a continuous reaching law is designed to reduce the chattering which caused by the computation time delays and limitations of control. Simulation results verify the feasibility and effectiveness of the control strategy.

In this paper, a combined formation control of nonholonomic wheeled mobile robots (WMR) is presented. In this method, the sliding mode control (SMC) strategy is used to solve the tracking problem of any robot agent. In our scenario, we assume the static and dynamic obstacles in the working environment. For guaranteeing obstacle avoidance, we use the artificial potential field method in which the coefficient of attractive and repulsive functions is determined by a Mamdani fuzzy system. Moreover, in order to maintain the desired formation considered between WMRs a fuzzy system is used to control the position and orientation of any agent with respect to the desired formation. The efficiency and simplicity of proposed control scheme has been proved by simulation on different situations.

In this paper, we propose an inverse optimal design method of a distributed graphical formation control of multiple mobile robots, where the group of robots configures the desired formation and moves with the same group velocity under the undirected graph topology. The robots' dynamics and kinematics are considered in the design. Under the assumption of perfect angular velocity tracking, the proposed protocol guarantees inverse optimality with respect to a meaningful cost function. Backstepping technique is employed to relax the assumption. Finally, the numerical simulation is carried out to verify the effectiveness of the proposed method.

Recently, usage of autonomous wheeled mobile robots (WMRs) is significantly increased in different industries such as manufacturing, health care and military and there exist stringent requirements for their safe and reliable operation in industrial/commercial environments. In addition, autonomous multi-agent mobile robot systems in which specific numbers of robots are cooperating with each other to accomplish a task is becoming more demanding in different industries in the age of technology enhancement. Consequently, development of fault tolerant controller (FTC) for WMRs is a vital research problem to be addressed in order to enhance the safety and reliability of mobile robots. The main aim of this paper is to develop an actuator fault tolerant controller for both single and multiple-mobile robot applications with the main focus on differential derive mobile robots. Initially, a fault tolerant controller is developed for loss of effectiveness actuator faults in differential drive mobile robots while tracking a desired trajectory. The heading and position of the differential drive mobile robot is controlled through angular velocity of left and right wheels. The actuator loss of effectiveness fault is modeled on the kinematic equation of the robot as a multiplicative gain in the left and right wheels angular velocity. Accordingly, the aim is to estimate the described gains using joint parameter and state estimation framework. Toward this goal, the augmented discrete time nonlinear model of the robot is considered. Based on the extended Kalman filter technique, a joint parameter and state estimation method is used to estimate the actuator loss of effectiveness gains as the parameters of the system, as well as the states of the system. The estimated gains are then used in the controller to compensate the effect of actuator faults on the performance of mobile robots. In addition, the proposed FTC method is extended for the leader-follower formation control of mobile robots in the presence of fault in either leader or followers. Multi agent mobile robot system is designed to track a trajectory while keeping a desired formation in the presence of actuator loss of effectiveness faults. It is assumed that the leader controller is independent from the followers and is designed based on the FTC frame work developed earlier in this document. Also, the fault is modeled in the kinematic equation of the robot as a multiplicative gain and augmented discrete-time nonlinear model is used to estimate the loss of effectiveness gains. The follower controller is designed based on feedback linearization approach with respect to the coordinates of the leader robot. An extended Kalman filter is used for each robot to estimate parameters and states of the system and as the fault is detected in any of the followers, the corresponding controller compensates the fault. Finally, the efficacy of the proposed FTC framework for both single and multiple mobile robots is demonstrated by experimental results using Qbot-2 from Quanser. To sum up, a fault tolerant controller scheme is proposed for differential drive mobile robots in the presence of loss of effectiveness actuator faults. A joint parameter and state estimation scheme is utilized based on EKF approach to estimate parameters (actuator loss of effectiveness) and the system states. The effect of the estimated fault is compensated in the controller for both single robot and formation control of multiple mobile robots. The proposed schemes are experimentally validated on Qbot-2 robots.

In this paper, the application of wheeled mobile robot (WMR) formation control in diffusion process characterization and control is discussed. We present a review over the current approaches on mobile robot formation control. A new consideration is presented on formation control within the framework of networked control system with wireless communication. The potential benefits of robot formation in distributed diffusion process measurement and control are discussed. In this paper, we present a new nonlinear control law for a general formation that can be useful in diffusion process boundary measurement. Then, we introduce our on-going project called Mobile Actuator and Sensor Network (MAS-net) on the diffusion process characterization and control. Experiment results are presented to illustrate how pattern formation can be achieved in MAS-net.

Cooperation among mobile robotic platforms is beneficial for various industrial applications, particularly in the warehouse and logistics sector. Formation control of mobile robots for collaborative transportation of an object, also known as collective transport, is a key challenge for cooperative robotic systems. This paper investigates communications-based formation control which is a promising approach. Based on an analytic model for wirelessly controlled leader-follower formation, the impact of connectivity imperfections on path-tracking performance has been investigated for two different types of mobile robots. Performance evaluation provides insights for wireless-centric system design.

Formation Control of Mobile Robots Based on Interconnected Positive Systems

In literature leader — follower strategy has been used extensively for formation control of car-like mobile robots with the control law being derived from the kinematics. This paper takes it a step further and a nonlinear control law is derived using Lyapunov analysis for formation control of car-like mobile robots using robot dynamics. Controller is split into two parts. The first part is the development of a velocity controller for the follower from the error kinematics (linear and angular). The second part involves the use of the dynamics of the robot in the development of a torque controller for both the drive and the steering system of the car-like mobile robot. Unknown quantities like friction, desired accelerations (unmeasured) are computed using an online neural network. Simulations results prove the ability of the controller to effectively stabilize the formation while maintaining the desired relative distance and bearing.

This article addresses the problem of leader-follower formation control of mobile robots using only onboard monocular cameras that subjected to visibility constraints. An adaptive image-based visual servoing control strategy was proposed following the prescribed performance control methodology. First, the leader-follower visual kinematics in the image plane and an error transformation with predefined performance specifications are presented. Then, an adaptive control law with online estimating the inverse height between the optical center of camera and the single feature point attached to leader is designed to ensure the global stability of the closed-loop system. Finally, the applicability and performance of the proposed control scheme are demonstrated by the numerical simulations and hardware experiments. Compared with other formation control schemes, our solution relies only on onboard visual sensors without communication, since it does not need the relative angle/distance between the robots, or the velocity of the leader. Moreover, it guarantees the prescribed transient and the steady-state performance besides the visibility constraints.

This paper proposed CTC (Computed Torque Control) with NDOB (Non-linear Disturbance Observer) to compensate disturbance for formation control of mobile robot. The kinematics models of robot is used to solve the formation control problem. The robot formation was formed using the SBC (Separation-Bearing Control) approach. However, in this paper also used SSC (Separation-Separation Control), because SSC approach can avoid collision between follower if one of the follower affected by disturbance. In this case, CTC is used to control the dynamics of the robot, but the controller has poor performance when the robot was affected by disturbance, consequently the formation that has been formed is interrupted when tracking trajectory. Under these conditions, NDOB is designed to estimate disturbance in robots. The simulation results show that CTC with NDOB succeeds to reducing the effect of disturbance on the robot so that the formation can be maintained when any follower was affected by disturbance.