Dynamic characteristics of large civil infrastructures have been monitored for safe operation and efficient maintenance of the structures. To measure vibration data, the conventional system uses cables causing very expensive costs and inconvenience for installation. Therefore, various wireless sensor nodes have been developed to replace the conventional wired system. However, there remain lots of issues to be resolved such as power supply, data loss, data security, etc. In this study, smart distributed sensor node (SDSN) was developed to measure vibration data. The SDSN is basically timely synchronized one-channel data acquisition system. It consists of its local time clock with high accuracy and SD memory card or local data storage. It is designed for temporal measurement, not long-term monitoring, since it can operate several hours using embedded batteries. Laboratoy tests were carried to verify the performance of the developed SDSN compared with conventional wired sensors. Several application examples for large civil infrastructure were also suggested.

This study presents a method to monitor cable force using an Imote2/SHM-DAQ sensor node and a PZT sensor. The following approaches are carried out to achieve the objective. Firstly, the principle of piezoelectric material (e.g., PZT) as a strain sensor is reviewed. According to its piezoelectric features, the use of PZT sensor for strain measurement of a stay cable is presented. Secondly, the design of the data acquisition sensor node Imote2/SHM-DAQ is described. The sensor node is used to monitor strain-induced voltage from the PZT sensor. The advantages of the system are cheap, and enable for wireless communication and automated operation. Finally, the feasibility of the sensing system is evaluated on a lab-scale stay cable.

This paper describes efficient flight control algorithms for building a reconfigurable ad-hoc wireless sensor networks between nodes on the ground and airborne nodes mounted on autonomous vehicles to increase the operational range of an aerial robot or the communication connectivity. Two autonomous flight control algorithms based on adaptive gradient climbing approach are developed to steer the aerial vehicles to reach optimal locations for the maximum communication throughputs in the airborne sensor networks. The first autonomous vehicle control algorithm is presented for seeking the source of a scalar signal by directly using the extremum-seeking based forward surge control approach with no position information of the aerial vehicle. The second flight control algorithm is developed with the angular rate command by integrating an adaptive gradient climbing technique which uses an on-line gradient estimator to identify the derivative of a performance cost function. They incorporate the network performance into the feedback path to mitigate interference and noise. A communication propagation model is used to predict the link quality of the communication connectivity between distributed nodes. Simulation study is conducted to evaluate the effectiveness of the proposed reconfigurable airborne wireless networking control algorithms.