Distributed Mobile Robots Research Articles

Non-line-of-sight error mitigating algorithms for transmitter localization based on hybrid TOA/RSSI measurements

Rendezvous control of multiple robots without losing network connectivity has important implications in multi-robot system including formation control, coordinated task assignments, and cooperative robotic missions. This paper introduces a new coordinate-free, bearing-based algorithm to enable rendezvous of distributed mobile robots at any designated leader robot node using hierarchical tracking of wireless network topology. An assumption is made that the robot can only sense and communicate with their neighbors (i.e., local sensing). The proposed approach preserves connectivity during the rendezvous task, adapts to dynamic changes in the network topology (e.g., losing or re-gaining a communication link), and is tolerant of mobility faults in the robots. We theoretically analyze the proposed algorithm and experimentally demonstrate the approach through simulations and extensive field experiments. The results indicate that the method is effective in a variety of realistic scenarios in which the robots are distributed in a cluttered environment.

Multi-robot rendezvous based on bearing-aided hierarchical tracking of network topology

Rendezvous control of multiple robots without losing network connectivity has important implications in multi-robot system including formation control, coordinated task assignments, and cooperative robotic missions. This paper introduces a new coordinate-free, bearing-based algorithm to enable rendezvous of distributed mobile robots at any designated leader robot node using hierarchical tracking of wireless network topology. An assumption is made that the robot can only sense and communicate with their neighbors (i.e., local sensing). The proposed approach preserves connectivity during the rendezvous task, adapts to dynamic changes in the network topology (e.g., losing or re-gaining a communication link), and is tolerant of mobility faults in the robots. We theoretically analyze the proposed algorithm and experimentally demonstrate the approach through simulations and extensive field experiments. The results indicate that the method is effective in a variety of realistic scenarios in which the robots are distributed in a cluttered environment.

離散事象ネットによるタスク間同期通信を用いたネットワーク型分散ロボットシステムの制御プログラム設計

離散事象ネットによるタスク間同期通信を用いたネットワーク型分散ロボットシステムの制御プログラム設計

Leader election algorithms for static swarms

Work solutions are proposed for problems of leader definition and role distribution in homogeneous groups of robots. It was shown that transition from a swarm to a collective of robots with hierarchical organisation is possible using exclusively local interaction. The local re-voting algorithm is central to the procedure for choice of leader while distribution of roles can be achieved by a wave method. The basis for this approach is the static swarm model characterised by the absence of a set control centre; it represents the network fixed at some time interval as a set of locally interacting agents. A task of cooperative hunting by distributed mobile robots based on local interaction was considered. Two strategies were used for the hunting task solution: individual hunting and pack-hunting. Simulation results showed that symbiosis of leader election and role distribution procedures has advantages over the individual strategy.

VCS-based motion planning for distributed mobile robots: collision avoidance and formation

This paper addresses decentralized motion planning among a homogeneous set of feedback-controlled mobile robots. It introduces the velocity obstacle, which describes the collision between robot and obstacle, and the hybrid interactive velocity obstacles are designed for collision checking between interacting robots. The (sub)goal selection algorithm is also studied for formation control, then the preferred velocity is designed for robot tracking its desired (sub)goal. Furthermore, the rules for the size regulation of obstacle are presented to avoid conservative motion planning and enhance the safety. Then, we establish a novel Velocity Change Space (VCS), map the velocity obstacles, the desired (sub)goal and the reachable velocity change window before collision in this space, and directly get the new velocity by a multi-objective optimization method. We apply VCS-based motion planning methods to distributed robots, and simulation is used to illustrate the good performances with respect to the un-conservative, foresighted and multi-objective optimal motion planning, especially the successful application in the formation control of the multi-robot system.

Improvement of group performance of job distributed mobile robots by an emotionally biased control system

This paper deals with the implementation of emotions in mobile robots performing a specified task in a group in order to develop intelligent behavior and easier forms of communication. The overall group performance depends on the individual performance, group communication, and the synchronization of cooperation. With their emotional capability, each robot can distinguish the changed environment, can understand a colleague robot’s state, and can adapt and react with a changed world. The adaptive behavior of a robot is derived from the dominating emotion in an intelligent manner. In our control architecture, emotion plays a role to select the control precedence among alternatives such as behavior modes, cooperation plans, and goals. Emotional interaction happens among the robots, and a robot is biased by the emotional state of a colleague robot in performing a task. Here, emotional control is used for a better understanding of the colleague’s internal state, for faster communication, and for better performance eliminating dead time.

Adaptive task assignment for multiple mobile robots via swarm intelligence approach

This paper describes an adaptive task assignment method for a team of fully distributed mobile robots with initially identical functionalities in unknown task environments. A hierarchical assignment architecture is established for each individual robot. In the higher hierarchy, we employ a simple self-reinforcement learning model inspired by the behavior of social insects to differentiate the initially identical robots into “specialists” of different task types, resulting in stable and flexible division of labor; on the other hand, in dealing with the cooperation problem of the robots engaged in the same type of task, Ant System algorithm is adopted to organize low-level task assignment. To avoid using a centralized component, a “local blackboard” communication mechanism is utilized for knowledge sharing. The proposed method allows the robot team members to adapt themselves to the unknown dynamic environments, respond flexibly to the environmental perturbations and robustly to the modifications in the team arising from mechanical failure. The effectiveness of the presented method is validated in two different task domains: a cooperative concurrent foraging task and a cooperative collection task.

Cooperative hunting by distributed mobile robots based on local interaction

This paper proposes a distributed control approach called local interactions with local coordinate systems (LILCS)to multirobot hunting tasks in unknown environments, where a team of mobile robots hunts a target called evader, which will actively try to escape with a safety strategy. This robust approach can cope with accumulative errors of wheels and imperfect communication networks. Computer simulations show the validity of the proposed approach.

2P2-C34 Decentralized Formation Control for Small-Scale Mobile Robot Teams

We present a new formation control framework for small-scale, distributed mobile robot teams that can adjust their formation to adapt to a variety of circumstances. Specifically, a neighbor-referenced decentralized approach is proposed to generate and keep geometric shapes. It is also demonstrated by simulation that robots continue to strive toward achieving their mission even if a part of team is unable to function normally.

Robot and Sensor Networks for First Responders

The need to collect, integrate, and communicate information effectively in emergency response scenarios exceeds the state of the art in information technology. This emergency response problem provides an interesting and important test bed for studying networks of distributed mobile robots and sensors. Here, we describe the component technologies required to deploy a networked-robot system that can augment human firefighters and first responders, significantly enhancing their firefighting capabilities. In a burning building at a firefighting training facility, we deployed a network of stationary Mote sensors, mobile robots with cameras, and stationary radio tags to test their ability to guide firefighters to targets and warn them of potential dangers. Our long-term vision is a physical network that can sense, move, compute, and reason, letting network users (firefighters and first responders) Google for physical information - that is, information about the location and properties of physical objects in the real world.

A "constrain and move" approach to distributed object manipulation

Studying the system dynamics, this research is an attempt to understand and design the basic robot behavior, information system, and distributed cooperation strategies required by a group of cooperative behavior-based mobile robots for handling an object. A new concept to develop distributed cooperation strategies to carry a load is introduced. In this method, the task of transferring the object is divided into two independent executable subtasks: constraining and moving the load. Each subtask is assigned to a group of distributed mobile robots. Based on this idea (constrain-move concept), two distributed cooperation strategies to turn the object about a fixed point and to move it along a straight line are introduced. The constrain-move concept is generalized for lifting and lowering the object. It is noted that weight of the payload can be used by the robots as a natural constraint on the object. Utilizing this natural constraint, a distributed cooperation strategy and an information system to lift and lower the object are introduced. The coordination protocols are devised in such a way that the robots can control movements of the object using their own sensory information and some static data communicated between the team members. Simulation and experimental results are given to support the proposed approach.

Line and circle formation of distributed physical mobile robots

The formation problem of distributed mobile robots was studied in the literature for idealized robots. Idealized robots are able to instantaneously move in any directions, and are equipped with perfect range sensors. In this study, we address the formation problem of distributed mobile robots that are subject to physical constraints. Mobile robots considered in this study have physical dimensions and their motions are governed by physical laws. They are equipped with sonar and infrared range sensors. The formation of lines and circles is investigated in detail. It is demonstrated that line and circle algorithms developed for idealized robots do not work well for physical robots. New line and circle algorithms, with consideration of physical robots and sensors, are presented and validated through extensive simulations. © 1997 John Wiley & Sons, Inc.