Wireless Sensor and Actuator Networks: Algorithms and Protocols for Scalable Coordination and Data Communication

9.4 SELECTING BEST ROBOT(S) WITH NONNEGLIGIBLE COMMUNICATION COSTS

If the robot network is disconnected then sensor nodes may be used to connect some robots. Sensors and robots may both participate in the same flooding protocol, with different transmission ranges being available to them. Robots may apply smaller backoff waiting times for retransmissions, so that they get a priority over sensors for retransmitting. If the transmission region (the set of its neighbors) of a particular sensor or robot is not covered by all received transmissions before the time runs out, the node retransmits the message. For simplicity, we assume here that the robot network is connected, and discuss further only robot-robot communication.

Solutions for robot-robot coordination described in this section do not depend on the particular environment served by networked robots. One such environment of interest to us are wireless sensor and robot networks (WSRNs), as an extension of MRS. Wireless sensor and robot networks consist of sensors and robots linked by wireless medium to perform distributed sensing of the physical world, processing of sensed data, making decisions, and acting upon sensed events (Fig. 9.3). We will illustrate our problem statement using this scenario. In many cases, the robot that receives the report may itself be the best candidate for responding. However, a remote robot could receive the report. Upon event occurrence (e.g., a fire, or the failure of a sensor), sensors detect events ...