Autonomous network repairing of a home security system using modular self-reconfigurable robots

Traditional wheeled robots cannot easily adapt to complex home environments with stairs and doorsills. This paper presents the design and implementation of a novel wireless sensor network based home security system with a modular self-reconfigurable robot (Transmote) as the mobile node. The security system is composed of some static monitoring nodes, a Transmote, and a home server. Static nodes with pyroelectric infrared (PIR) sensor and digital camera are mounted on doorframes and windows to detect intruders and send intrusion alarm messages to the home server. Transmote with PIR sensor and camera can patrol in the house for security surveillance. Transmote also can provide network repairing service when some static router nodes fail. Transmote modules and static monitoring nodes are controlled by two different wireless sensor networks. The remote house owner can get the alarm messages through Internet. Transmote can transform into I-shaped or O-shaped configuration according to different locomotion requirements. A prototype system has been implemented and some performance tests have been done. Experimental results show that the I-shaped Transmote can pass through an 8.8 cm high and 10 cm wide channel. The velocity of the I-shaped Transmote is up to 3 m/min and the maximum velocity of O-shaped Transmote is 9.3 m/min. A 12 kB captured photo can be transmitted to the gateway through 15 hops without any packet loss.