Wireless navigation system for a self-propelled car with a rotational directional antenna

Indoor positioning based on wireless signal strength is inaccurate due to unpredictable wireless channels at complex environments. In this paper, we propose another approach for guiding a self-propelled car. We implement a wireless navigation system which consists of a self-propelled car, several Zigbee reference nodes, and a suit of navigation programs. The reference nodes, which are placed on the desired path, send beacon packets to indicate the direction for the self-propelled car. Only one reference node is active at a time. When the self-propelled car arrives at the current active node, the guiding duty is switched to the next reference node. By this way, the self-propelled car can visit these reference nodes one by one to the destination. The self-propelled car, equipped with a rotational directional antenna, continues rotating its antenna to find the direction of the active reference node according to the signal strength of receiving packets. The wireless navigation system is proved effective by prototyping.