Research For Time Synchronization And Positioning In Swarm Robots Based On Wireless Network

In recent years, both Wireless Sensor Networks(WSN) and mobile multi-robot technology have been integrated into wireless communications, machinery, computers, electronics and other disciplines, and highly valued in research field. Based on the advantages, swarms of robotic nodes can achieve to the location of close and long-distance in an unknown environment.The related research and key technologies at home and abroad in the field of WSN and mobile multi-robot had been introduced in this paper, and then the comparison had also been given out. After the research for typical time synchronization in WSN, an improved algorithm was proposed and the synchronization error between the nodes was estimated. Through the analysis of these two positioning technology, the way of positioning with ultrasonic and radio signal attenuation was also proposed. When the distance was less than 5 meters, swarms of robotic nodes could perceive of the surrounding information and complete their positioning by using ultrasonic, whereas, nodes would start Received Signal Strength Indication(RSSI) automatically for positioning. Depending on fusion of the distance information, nodes could calculate the position in two-dimensional coordinates with the triangular localization algorithms.The research about time synchronization and positioning system of nodes was divided into three parts, that is swarm of robotic nodes, time synchronization algorithm and positioning technology. Swarms of robots could be designed in mini-car with three wheels for the structure. The nodes hardware design mainly includes:wireless communication module, motor drive module, ultrasonic sensors module for ranging, serial communication module and power module. Based on Two-way Synchronization and flooding, the proposed synchronization algorithm in this paper could reduce the number of exchange of information under the premise of synchronization precision. Localization for nodes uses ranging mechanism, by supporting RSSI and transit time of ultrasonic, all the nodes could achieve to positioning in an unknown environment.Swarms of robotic nodes based on WSN had been deployed for positioning test in both indoor and outdoor and could run well. With the mobile nodes had achieved a good positioning in the two-dimensional area, it confirmed the rationality of node design and algorithm. WSN can improve the capability of apperceiving surrounding environment for swarm of robots, and at the same time, the dynamic performance of the network nodes could be increased. By combination of these two technologies, it will have broad application prospects in the tracking of mobile target and others.