Multiple Mobile Robot System Research Articles

On robot-borne extended object tracking using the em algorithm

High precision tracking of all surrounding objects is a prerequisite to the autononious/senii-autononious management of multiple mobile robot systems. This task comprises not only tracking of moving objects, but also detection of obstacles or other stationary objects. We demonstrate that Expectation-Maximization applied to multiple object tracking is a promising method being flexible enough to handle the problems typical of robot-borne tracking, such as extended objects, dense object environment, mutual occlusions. Observations and preliminary conclusions based on simulated and real sensor data are discussed.

Human-supervised multiple mobile robot system

In order that robots may achieve tasks in unknown environments, research focusing on the following three points must be conducted: (1) design of commands from the operator to the robots; (2) environmental recognition to show the operator information about the remote work area where robots are working; and (3) interface between a system and the operator and information display of the work area for the operator. For (1), the focus is on the operation of the multiple robots by a single operator. For (2), the problem is divided into two parts; object recognition and self-positioning. As for (3), a graphical user interface is implemented. The operator mainly uses a mouse to input commands, and the operator watches a virtual environment to monitor remote working areas. The virtual environment is constructed with the environment information acquired by the method described in (2) above. After the problems mentioned above are solved, our system will provide a flexible command and monitoring structure and an operator would be able to command the robots appropriately. These are the main advantages of the method we are proposing. We verified the effectiveness of the proposed methods in experiments.

A Space-Division Optical Wireless Communication System for Fully Distributed Multiple Autonomous Mobile Robots

This paper describes the realization of a space-division optical communication system specifically designed to perform local inter-robot communication in fully distributed multiple autonomous mobile robot systems. Requirements for autonomy and robustness of communication functions among moving robots are discussed. The communication system uses a set of modules, or transceivers, which is arranged in the circumference of the robot body. Each module comprises an IR detector/receiver and an IR transmitter. Each IR module detects the angle of incidence of infrared rays. Space-division communication networks can be created, because a robot can commumcate with more than one robot through different modules at the same time. Hardware realization and performance measurements are illustrated to reveal the effectiveness of the developed system.

複数移動ロボットによる持ち上げ作業のためのセンシング計画

We are going to explain about sensing strategy of multiple mobile robot system, which is suitable for transport various objects whose mass and center of gravity are usually unknown. Our proposal is based on statics of manipulation by multiple fingers. We apply this analysis and sensing problem to optimal planning of multiple mobile robots. The main topic of in this paper is optimizing position of robots before the robots get started to lift an object up. Optimization in this case means maximizing probability of being successful in lifting an unknown object, without any overload situation. If lifting has resulted in failure, the robots renew the parameter of the object by their sensing data and plan their optimal lifting positions again. This optimizing process says that we can give an optimized solution according to probability of being successful, if there is causal relationship between a property of an object, a plan of robots, and a result of execution. We have verified an effect of proposed strategy by numerical computation.

Evolving communicating controllers for multiple mobile robot systems

Multiple mobile robot systems working together to achieve a task have many advantages over single robot systems. However, the planning and execution of a task which is to be undertaken by multiple robots is extremely difficult. To date no tools exist which allow such systems to be engineered. One of the key questions that arises when developing such systems is: does communication between the robots aid the completion of the task, and if so what information should be communicated? This paper presents the results of an investigation undertaken to address the above question. The approach adopted is to utilize genetic programming (GP) with the aim of evolving a controller, and letting the evolution process determine what information should be communicated and how best to use this information. A number of experiments were performed with the aim of determining the communication requirements. The results of these experiments are presented in this paper. It is shown that the GP system evolved controllers whose performance benefitted as a result of the communication process.

Distributed Control of a Multiple Tethered Mobile Robot System for Highway Maintenance and Construction

The development of a distributed control system for a multiple mobile robot system is described. The mobile robots considered have been termed tethered mobile robots (TMRs). The TMRs are differentially steered, wheeled mobile robots tethered to a support vehicle, and they have been designed for automating highway maintenance and construction. The control system consists of a network of a host computer and several real‐time dynamic controllers running under Windows for Workgroups and DOS operating systems, respectively. Advanced industrial embedding technology is applied to the hardware design, and the system's fault‐tolerance is achieved from a distributed architecture and overall condition monitoring. The object‐oriented and hardware‐independent software programming provides a graphic user interface and flexibility for a large number of highway maintenance and construction tasks. It also provides convenience for any other mobile robotics research applications.

Simulation Language for Multiple Mobile Robots

The purpose of this paper is to propose a design concept for a simulation language to be used in path planning in a multiple mobile robots system. The paper also includes some examples of programming of path planning for multiple mobile robots. In some path planning problems with mobile robots, graph theory can be a powerful tool. In our system, the environment information of the robots is represented in a graph structure. By handling this graph with a programming language, path planning tasks can be executed in a systematic way. Each task of the multiple mobile robots can be described using a Petrinet expression, and several features of the given robot system, for example, the optimum path problem, the deadlock problem of multiple robots, etc., can be deduced using the network model.

Motion skills in multiple mobile robot system

Abstract This paper deals with how to introduce motion skills in motion planning of multiple mobile robots. The motion skills are defined as rules of “IF (a specific situation) THEN (a specific manner of motion)” type. Authors propose an algorithm for acquiring and utilizing the skills. First, the concept of sensor information pattern is introduced for recognizing the specific situation. Next, acquisition of the motion skills are made by induction process, which is accomplished by using hierarchical neural network. Last, simulations are made to show the effectiveness of the proposed algorithm.

Motion Planning of Multiple Mobile Robots Using Virtual Impedance

This paper proposes a planning method for multiple mobile robot systems. It has two characteristics: (1) Each robot plans a path on its own, without any supervisor; (2) The concept of cooperative motion can be implemented. A two-layered hierarchy is defined for a scheme of individual path planning. The higher layer generates a trajectory from the current position to a goal. The lower layer called“Virtual Impedance Metho” makes a real-time plan to follow the generated trajectory while avoiding obstacles and avoiding or cooperating with other robots. This layer is composed of four modules called, “watchdog”, “deadlock solver”,“blockade solver”, and “pilot”. The local equilibrium is detected by the watchdog and cancelled by the deadlock solver or the blockade solver. Simulation results indicate the effectiveness of the proposed method.

２台の移動ロボットの協調による搬送制御

A coordinated control method for two mobile robots without explicit communication is presented in this paper. Concretely, transferring control by cooperation of two robots is realized from the viewpoints of mechanical design and of control system design. In the mechanical design, compliance mechanism with 3 degrees of freedom is added on one of the robots in order to avoid extreme inner forces between the robots. In the control system design, leader-follower method is adopted. “Virtual Impedance Method” is used for controlling the follower robot. A deadlock problem, where a robot stops at some other positions from a target position of the robot, is solved by transforming lateral virtual forces to virtual moments. Effectiveness of the proposed method is verified by experimental results. The proposed method is applicable to multiple mobile robot system by increasing the number of followers.

群秩序生成可能な追従戦略を用いた複数移動ロボット系の動作計画

In this paper, we propose“a strategy of following another robot”for motion planning of multiple mobile robot system, which gives order to behavior of robots from the viewpoint of angular velocities of robots. In the strategy, one robot (Follower, F) tries to follow another robot ( Leader, L) which is in front of F and goes in the same direction as F. The strategy is implemented to Virtual Impedance Method, which was proposed by authors. Each robot has two kinds of impedance mode: one is avoiding mode, in which each robot moves individually and independently. The other is following mode, in which each follows L by means of keeping constant distance from L. Each robot decide the mode with other robots in real time by using rule-based method. The simulation indicates effectiveness of the proposed strategy from angular velocities of robots.

仮想的なインピーダンスを用いた複数移動ロボット系の動作計画

This paper proposes a planning method for multiple mobile robots system. It has two characteristics as follows: (1) Each robot plans a path individually. There is no supervisor. (2) The concept of cooperative motion can be implemented. A two layered hierarchy is defined for a scheme of individualrobot path planning. The higher layer generates a trajectory from the current position to the goal. The lower layer called “Virtual Impedance Method” makes a real-time plan to follow the generated trajectory while avoiding obstacles and avoiding/cooperating other robots. This layer is composed of four modules called “watchdog”, “deadlock solver”, “blockade solver” and “pilot”. The local equilibrium is detected by the watchdog and canceled by the deadlock solver or the blockade solver. Simulation results indicate eff eciveness of the proposed method.

A flexible multiple mobile robots system

Optimal performance of a manufacturing layout consisting of several mobile robots performing specific transportation tasks is addressed. A synergistic approach based on decentralized path planning, heuristic-algorithm-based navigation, and localized collision avoidance is presented. A comprehensive, flexible multiple mobile robots system (MMRS) consisting of standard patterns, a local controller, and individual mobile robots is described. The mobile robots are capable of performing their own path planning and collision avoidance by means of ultrasonic sensors, standard patterns, and rotary optical encoders. Specially designed algorithms for the mobile robot and local controller are presented. To ensure greater flexibility in designing the layout, the MMRS was interfaced with a specially designed CAD subsystem. Simulations using varying numbers of robots were performed on a sample layout that was designed using the CAD subsystem. The results of the simulation illustrate the validity of the approach.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>