Comprehensive review on controller for leader-follower robotic system

985-1007This paper presents a comprehensive review of the leader-follower robotics system. The aim of this paper is to find and elaborate on the current trends in the swarm robotic system, leader-follower, and multi-agent system. Another part of this review will focus on finding the trend of controller utilized by previous researchers in the leader-follower system. The controller that is commonly applied by the researchers is mostly adaptive and non-linear controllers. The paper also explores the subject of study or system used during the research which normally employs multi-robot, multi-agent, space flying, reconfigurable system, multi-legs system or unmanned system. Another aspect of this paper concentrates on the topology employed by the researchers when they conducted simulation or experimental studies

Coordinated multi-robot formation control

Tese de doutoramento. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 201

Distributed Formation Control for Ground Vehicles with Visual Sensing Constraint

Formation control combined with different tasks enables a group of robots to reach a geographical location, avoid a collision, and simultaneously maintain the designed formation pattern. The connection and perception are critical for a multi-agent formation system, mainly when the robots only use vision as a communication method. However, most visual sensors have limited Field-of-view (FOV), which leaves some blind zones. In this case, a gradient-based distributed control law can be designed to keep every robot in the visible zones of other robots during the formation. This control strategy is designed to be processed independently on each vehicle with no network connection. This thesis assesses the feasibility of applying the gradient descent method to the problem of visual constraint vehicle formation

Modelling and control of the coordinated motion of a group of autonomous mobile robots

The coordinated motion of a group of autonomous mobile robots for the achievement of a coordinated task has received signifcant research interest in the last decade. Avoiding the collisions of the robots with the obstacles and other members of the group is one of the main problems in the area as previous studies have revealed. Substantial amount of research effort has been concentrated on defning virtual forces that will yield reference trajectories for a group of autonomous mobile robots engaged in coordinated behavior. If the mobile robots are nonholonomic, this approach fails to guarantee coordinated motion since the nonholonomic constraint blocks sideway motions. Two novel approaches to the problem of modeling coordinated motion of a group of autonomous nonholonomic mobile robots inclusive of a new collision avoidance scheme are developed in this thesis. In the first approach, a novel coordination method for a group of autonomous nonholonomic mobile robots is developed by the introduction of a virtual reference system, which in turn implies online collision-free trajectories and consists of virtual mass-spring-damper units. In the latter, online generation of reference trajectories for the robots is enabled in terms of their linear and angular velocities. Moreover, a novel collision avoidance algorithm, that updates the velocities of the robots when a collision is predicted, is developed in both of the proposed models. Along with the presentation of several coordinated task examples, the proposed models are verifed via simulations. Experiments were conducted to verify the performance of the collision avoidance algorithm

Vision based automated formation for multi robot cooperation

In a multi robot system, robots are required to cooperate with each other, and therefore should have the ability to make their own decision based on multiple input sensors not only from the robots, but also from nearby robots. The task of carrying oversized objects of different shapes poses a challenge in selecting an appropriate group formation. Hence, the main objective of this project is to establish an algorithm that enables multi robot system to carry large load by automatically selecting the required group formation to successfully execute the task. At first, a robot will need to identify the shape of the object (oversized bar, rectangular, square or circular shapes). Then, the robots will form a suitable formation to carry the object. There are two main problems in this project. First, the capability of the robot to identify the shape of the object because the object’s image will be a bit skew form the actual shape, due to the slanting angle of the camera used to detect the shapes of the objects. The second challenge is maintaining the formation of the robots, while carrying the load on top of the robots, to a specified destination. A multi robot system, built in-house is used in the experiments to investigate the performance of the algorithm proposed. Algorithms implemented in this project are leader-follower and behaviour based strategy. One of the robots will operate as the command giver or the leader to the other robots. The algorithm consists of communication strategies and autonomous decision making capability. The robot will be communicating with each other using Xbee wireless modules and extracting the behaviour of the other robots. Sensors placed around the body of the robots are utilized to detect their relative distance, and hence, used to maintain their formation, so as to prevent the load from falling down. All the decisions are made by the robots autonomously via the onboard controllers. The multi robot system is shown to be able to autonomously determine the shape of the different oversized objects, thus appropriately change into formations capable of transporting large objects to a specified destination point autonomously, with no outside intervention

Application of Odometry and Dijkstra Algorithm as Navigation and Shortest Path Determination System of Warehouse Mobile Robot

One of the technologies in the industrial world that utilizes robots is the delivery of goods in warehouses, especially in the goods distribution process. This is very useful, especially in terms of resource efficiency and reducing human error. The existing system in this process usually uses the line follower concept on the robot's path with a camera sensor to determine the destination location. If the line and destination are not detected by the sensor or camera, the robot's navigation system will experience an error. it can happen if the sensor is dirty or the track is faded. The aim of this research is to develop a robot navigation system for efficient goods delivery in warehouses by integrating odometry and Dijkstra's algorithm for path planning. Holonomic robot is a robot that moves freely without changing direction to produce motion with high mobility. Dijkstra's algorithm is added to the holonomic robot to obtain the fastest trajectory. by calculating the distance of the node that has not been passed from the initial position, if in the calculation the algorithm finds a shorter distance it will be stored as a new route replacing the previously recorded route. the distance traversed by the djikstra algorithm is 780 mm while a distance of 1100 mm obtains the other routes. The time for using the Djikstra method is proven to be 5.3 seconds faster than the track without the Djikstra method with the same speed. Uneven track terrain can result in a shift in the robot's position so that it can affect the travel data. The conclusion is that odometry and Dijkstra's algorithm as a planning system and finding the shortest path are very efficient for warehouse robots to deliver goods than ordinary line followers without Dijkstra, both in terms of distance and travel time

Multi-robot Tethering Using Camera

An autonomous multi-robot or swarm robot able to perform various cooperative mission such as search and rescue, exploration of unknown or partially known area, transportation, surveillance, defence system, and also firefighting. However, multi-robot application often requires synchronised robotic configuration, reliable communication system and various sensors installed on each robot. This approach has resulted system complexity and very high cost of development

Characterization Of Cooperative Control For Multiple Non-Holonomic Wheeled Mobile Robots To Achieve Formation Tracking

Distributed control for cooperative system is an emerging research �eld in control system. This research focuses on characterization of the distributed control algorithm in solving formation tracking for multiple non-holonomic wheeled mobile robots. The existing research work mostly used mathematical approach to proof the convergence of controller but does not investigate how the parameters would a�ect the controller. Besides, usually only one communication topology is presented in solving formation tracking. Therefore, this research aims to �ll in the gap on current research by performing characterization of gain parameters in the distributed controller studied. Besides, several communication topologies are evaluated to understand how the neighbouring agents connected will impact the performance. A multi-agent system that consists of four wheeled mobile robots are investigated in this research using simulation approach. LabVIEWTM is used to simulate the multi- agent formation control. This research managed to perform the characterization of gain parameters and evaluate di�erent communication topologies. The characterization would complement the existing Lyapunov analysis thereby improving the research in cooperative formation control of wheeled mobile robot. This has helped to understand the how the distributed controller studied and used to tune the con- troller to solve the formation tracking. The formation tracking control is partially achieved and can be further improved by making the parameters adaptive to achieve state consensus