Towards Net-Centric System of Systems Robotics in Air, Sea And
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Towards Net-Centric System ofSystems Robotics in Air, Sea and Land Ted Shaneyfelt, Sevki Erdogan, Azim Maredia, Gnanadeep Vemuri, Bhargavaram Pachala, Dong Yue, Sohel Karovalia, Ming-Zhu Lu, Shi-Zhong Yang, and Chenyu Gao Autonomous Control Engineering Center Electrical and Computer Engineering Department The University ofTexas at San Antonio, TX, USA Near - The communication range is small and the robot can Abstract-This paper investigates how we can work towards only communicate with nearby robots. building net-centric swarms of land, sea and air robots working INF - The range is infinite and the robot can communicate together to accomplish a common goal. The goal is to bring with any robots in the working space regardless of the together swarms of robots from all three sectors to safely benefit physical size ofthe working space. mankind without increasing dangers in the process. Several platforms are explored for simulation to investigate swarm Communication Topology - Although a robot could robotics within heterogeneous environments. communicate with others randomly and arbitrarily, a structural rule is generally followed, describing a Communication Index Terms-Mobile robots, Net-centric, Simulation software, Topology. System ofsystems BROAD -Broadcast. A robot can send a message that is received by many robots. I. INTRODUCTION ADD - Addressable. A robot communicates with other HIS document identifies Network Centric System of robots using their particular addresses, which are typically TSystems of robots within a brief taxonomy of robotics predetermined. and swarm robotics, investigates some potential applications TREE - A robot can only communicate through a for such systems, and considers a road-map towards hierarchy. realization. Recent progress has been made in research GRAPH - Communication between robots follows some towards Net-Centric System of Systems of fault-tolerant other graph pattern. sensor networks [1] and robotic swarms. Net-Centric does not Communication Bandwidth: Data connections by cable imply totally autonomous systems, but rather using allow massive amounts of information to be transferred in a networking to enable people and systems to work together very short time. Conversely, wireless signals by submarines productively [2] and safely. A primary concern not covered in using sound waves carry only a small amount of data over a this paper is ethical use, which includes rights to privacy, relatively long period oftime. Regardless, some robots need to safety, etc. We overview some ofthe robotics developments at stop other processing in order to communicate due to limited the Autonomous Control Engineering lab at The University of processing resources. Bandwidth characterizes these aspects of Texas at San Antonio, and evaluate several robotics suites for communication cost. simulation. INF - Bandwidth limitations are negligible so that all desired communication is fast and easy. A. Robots MOTION - Robots must divert valuable processing A number ofresearchers have taken on the task ofdevising resources from other tasks to handle communication, so that taxonomies for robotics [3]-[8]. The taxonomy devised by communication is relatively expensive in terms of Dudek et al. follows [7]. processing. Collective Size - The number ofrobots in the workspace LOW -Bandwidth is narrow making communication ALONE -A single robot working alone in the workspace difficult or very expensive in terms ofprocessing. PAIR - Two robots working together in the workspace ZERO - No communication bandwidth is available. Lim - A limited number ofrobots in the working together Collective Reconfiguability - The ability of a Collective to INF -An unlimited number ofrobots working together reorganize its spatial configuration Communication Range - A robot cannot communicate with STATIC - Static arrangement; the topology is fixed. others outside ofits communication range. COMM - Coordinated rearrangement NONE -The robot cannot communicate with others under DYN - Dynamic rearrangement any condition. Processing Ability - Each unit ofthe Collective has a model ofprocessing and computation ability. 978-1-4244-2173-2/08/$25.00 ©2008 IEEE SUM -linear summation unit [9] one leader for each assigned task. Weakly centralized systems FSA - Finite state automaton utilize multiple master robots. We are primarily concerned PDA - Push-down automaton with weakly centralized systems that are capable of self TME- Turing machine equivalent; this computational organization, yet respond to higher level control. model is assumed by most robotic systems. We extend this classification by considering Net-Centric Collective Composition - Three important compositions in swarms as a subclass of'weakly-connected robots. Net-centric the Collective. swarms are capable of self-organization and discovery of one IDENT - Identical; each unit of the collective is another, yet capable of multiple levels of direct remote homogeneous in both form and function, i.e., in both operator intervention. We are specifically interested in hardware and software. coordination of systems, which involves land, sea and air HOM - Homogeneous; all of the units of the Collective based swarms of robots. Each of swarm is itself a complex, essentially have the same physical characteristics. independent system, yet all of them are required to work HET - Heterogeneous; the units of the Collective have together as a coordinated System ofSystems. different physical characteristics. General speaking, this also implies difference in the physical behavior. II. ApPLICATIONS OPPORTUNITIES FOR SWARM ROBOTIC SYSTEM OF SYSTEMS B. Swarm Robots Alessandro Farinelli et aI., [2] classify of swarm A. Steps towards realization robotics based on several levels: Cooperation level, The first step towards realization is to develop actual robots knowledge level, coordination level and organization level. in the lab on a small scale to discover physical characteristics This organization is shown in Fig. 1. and technologies that cannot be so easily simulated. This is Swarm robotics is distinguished from robotics in general by already well underway at the UTSA Autonomous Control the cooperation of robots to perform a task. Classification of Engineering laboratory with land and sea based robots, with swarms as cooperative robotics is the first level in the some initial work on air based robots. Small swarms ofrobots hierarchy. are being investigated with real equipment, while scalability The second level in hierarchy deals with knowledge will be tested with simulations based on the knowledge gained possessed among the robots. Robots are either aware of other working with real robots. robots in the swarm, or unaware. Awareness allows robots to After proof-of-concept is sufficiently accomplished with cooperate well with increased efficiency. At this level, we are small swarms of real robots, simulation can be used to test primarily concerned with swarm robots that are aware of one scalability to many robots working together as a net-centric another. System of Systems. Economically it is not feasible to The third level deals with coordination, which distinguishes experiment with such large scale System of Systems in early whether or not robots act in consideration of the actions of stages of research. There is also some risk of actual robots other robots. Robotic swarms can be classified according to experiencing damage during testing in a real environment, the strength of their coordination, which is affected by the which is avoided when doing simulations. Simulation can reliability of the coordination protocol. At this level, we are provide a safe environment where correct programming can be primarily concerned with strongly coordinated robotic verified before implementing some algorithms directly on swarms. robot. A fault in programming real robots could cause damage Swarms are further classified into centralized and to robots or their environment. Some tuning can be decided distributed organization. In distributed systems each robot acts during simulation so as to reduce the likelihood ofcollision. A and makes decisions autonomously. On the other hand, ifthere simulation can provide results that are not easily is a master robot in charge of the swarm, it is called a experimentally measurable with currently available centralized system. Strongly centralized systems have only technology. Testing of robots for long periods of time can cause wearing of robots which can be prevented using Cooperation simulations. There are some drawbacks to relying on simulations as well. For example, the result of simulations may not be always accurate as expected in real time. This Knowledge calls for both simulation and development ofphysical robotics in an integrated plan. Coordination Simulation is to be carried out to demonstrate the use of robotics in a net-centric System of Systems to profit mankind. We considered many applications, taking into account Organization negative consequences as well as benefits. For example, sending robots to dig through rubble after a major disaster in search for survivors could cause undue harm to people who INet-Centric I are trapped in the rubble ifthe robots are less able to adapt to Fig. 1. A taxonomy for swarm robotics people's cries for help or verbal cues from the disaster victims. Adapted from. Jacoffet aI., (2000) Cold Zone Commandpost rest &: recovery 1t Fig. 3. Coast Guard Deep Water Program 1tf$ human rescue workers. For this reason, use ofrobotic swarms is potentially most helpful