Modal Test And Damage Identification Based On Wireless Sensor

The structure health monitoring technology has been widely investigated andapplied in the field of civil engineering. The way of centralized data processing withwired sensors is widely used in traditional structural health monitoring system. Asthe development of wireless transmission technology and network protocol,especially the emergence of wireless smart sensor with data processing function,distributed data processing technology in local area is already applied in structuralhealth monitoring field. Based on wireless sensor platform Imote2, first, theapplication of Imote2in the Xihoumen Bridge is implemented; then the mobilewireless sensor system is developed; last, the damage identification technique basedon wavelet packet energy and sparse regularization is proposed.Main contents are included as follows:Firstly, reach on Imote2installed on the Xihoumen Bridge has been done toobserve the actual effect. A set of autonomous system with Imote2, sole panel andlithium battery is tested: data transmission distance, battery life and communicationjamming and so on. The result shows this system can availably accomplish themonitoring task. So we have installed four Imote2on the bridge for a long-termmonitoring.A mobile wireless sensor system is proposed for structural health monitoring,which is composed by wireless sensor, robot and remote-control system. Then anexperiment is done to verify the device practical applicability. The remote-controlrobot can move on the ferromagnetic surfaces with the magnet-wheeled and placethe wireless sensors on the structure accurately by mechanical arm. The structurevibration data is acquired by the wireless sensor and transmit it back to base station.After finished one point test, the robot can pick up the sensor then move to anothertest points. In this study, a laboratory experiment on sixteen-frame is conducted totest the performance of the mobile sensing system. The results show that the mobilewireless sensor has good potential to be used in SHM in future.A structural damage detection method based on the wavelet packet energy rateand sparse regularization is proposed. The finite modal is established to gain theacceleration data of the structure in the different extent of damage.Then the waveletpacket transform of the acceleration signal is carried out to obtain the energy as asensitivity matrix. The relation between the structural damage and measured waveletpacket energy is constructed by the sensitivity matrix. With considering thestructural damage sparsity conditions, the location and extent of damages areidentified by minimize the l1norm optimization problem. The numerical example of the truss structure with considering measurement noise, incomplete ofmeasurements and multi-damage cases are carried out.