Evaluation of shared tuple spaces as communication model for semi-autonomous robots in a mobile environment

Abstract

Robotics can be utilized more in emergency services, and a software platform for controlling many semi-autonomous can make it more alluring to use robots in this area. Using semi-autonomous robots can allow personnel to issue robots to perform complex task, without the need of extensive training, and it allows one person to control many robots alone. One challenging aspect of using robots in emergency situations is handling communication between devices in the system. Since emergency situations can be chaotic it must be assumed that the robots have to work in a segmented network, and devices in the system must be allowed to move. Due to the mobile environment, a spatial and temporal uncoupled communication model can be beneficial; it helps handle much of the complexity acquaint with a mobile environment.

A possible architecture for robots in a semi-autonomous robot platform has been discussed, and some features for a semi-autonomous robot control unit was implemented.

A shared tuple space was designed and implemented as a communication model for use in a mobile environment. The model is based on the client-server model, consisting of three main components: hosts, clients and name servers. Hosts act as buffers in the form of a tuple space, storing tuples from clients. Hosts can be accessed remotely over a network, and clients can insert, read, and withdraw tuples from hosts, thus providing a mechanism for passing data between devices. Clients provide a interface for processes to access the shared tuple space through. The client is also responsible for combine the content from the available hosts, constructing the shared tuple space as seen from the clients point of view. Name servers simply provide device detection, letting clients locate hosts. The use of this communication model grants the ability for clients to pass messages between each other without knowing which process will retrieve it, or at time the message is retrieved.

A set of experiments were performed to evaluate the performance of the implemented shared tuple space. Performance results show that the shared tuple space has good enough performance to be used as a communication model for messages that are not dependent on low latency. It is theorized that the important aspects of a communication model for a semi-autonomous robot platform is not low latency, but services provided by it. Messages requiring low latency should be sent over more efficient communication links, while the communication model should help remedy the complexity introduced by working in a mobile environment.