Multi-robot Communication Module Design And Implementation

With the development of robot technology and the needs of practical applications, research on the applications of multi-robot systems has been a trend. Multi-robot system has been paid more and more attention because of its advantages such as high parallelism, high distribution, high robustness and low individual requirement over single-robot system. Building map after exploring unknown environment is a classic problem in mobile robot research.With the multi-robot communication system, robots can provide current status and share informations to other members in order to achieve the coordination,.Therefore, it is meaningful that the development of multi-robot communication platform for multi-robot cooperative map exploration.The topic comes from National Natural Science Foundation program" The network environment based on swarm intelligence approach virtual machine Collaborative Platform". The program hopes to explore a new parallel computing model to control the large-scale group collaboration and verify performance through map building classic scene. The research team designed and produced dozens of homogeneous robot, which are low computing performance, smaller storage space, simple sensors and communications .These multi-robot systems have features like small size, high mobility, quick topology variation, low communication traffic and battery powered. For these features, following the principle of simple and reliable, a communication network is developed for multi-robot system. The specific content of this paper is as follows:(1) The design and implementation of hardware platform: According to local communication features of swarm intelligence, hardware uses IEEE 802.15.4-standard radio frequency chip CC2430, and is equipped with SMA antenna interface. The maximum communication range is up to 15 meters. The size is 25.4x35mm, low power consumption, so the module is suitable for our battery-small mobile robot. By the developed UART driver, data can transmit between the robot system and wireless communication module.(2) Design and Implementation of Protocol: Following the principle of simple, the IEEE 802.15.4 standard established for Low-Rate Personal Area Network is analyzed and adopted as physical and MAC protocol. The binary exponential backoff algorithm in MAC layer reduces packet collision. Application layer provides services like setting for robots , parameter inquiring and data transceiving.(3) Test Platform for RobotNet: A test platform is developed to evaluate the performance and functionality of the system. At static conditions and dynamic conditions,the test compares the impact of different baud rate, different send interval, different packet length, whether the node is transceiving at the same time on packet loss rate. And analysis of the experimental results.The results show that every robot can communicate with others by broadcasting. Users can adjust the transmission power by changing the transmission distance. The transmission distance is changed by controlling the transmit power. Channel sharing can realize by CSMA / CA mechanism. RobotNet has no network restrictions, is suitable for large-scale group communication. The test result show that packet loss rate is less than 3% at the dynamic conditions. RobotNet is simple and reliable for the research of swarm intelligence algorithm.