Design Of Zigbee-based Magnetic Anomaly Detection Node For Target Positioning And Implementation Of Positioning Algorithm

The location of underground or underwater target is often required in the military and geological prospecting application. However, such kind of target location detection is very hard to achieve due to the invisible nature of the target. The geo-magnetic anomaly detection (MAD) is a non-contact passive detection method. Thus it can work under any weather condition and perceive any type of ferromagnetism target in earth magnetic field. Since the ferromagnetism target can produce perturbation to the space magnetic field, we present a method to detect the location of concealed target based on its magnetic property.The non-linear target location detection algorithm is derived from non-linear model of3D magnetic field of point magnetic source. Based on this non-linear model and vector calculation, the algorithm is simplified into a linear form which can ease the further implementation. The parameter that has to be measured from sensor system is also determined. According to the requirement of location detection algorithm, the hardware of distributed MAD monitor system is designed. The system consists of one central controlling node and several terminal monitoring nodes. The communication between these nodes is achieved by using Zigbee wireless protocol or RS-485serial communication protocol selectively to transmit the control commands and synchronize the time. The HMC10533-axis anisotropic magnetoresistive sensor is used in terminal monitor node to sensing the external magnetic field. The signal from HMC1053is further conditioned by AD8556digital programmable instrumentation amplifier. Then the conditioned signal is acquired by multi-channel high-speed simultaneous sampling AD converter. The data is saved on SD memory card on each terminal node. After a full cycle of measurement finished, the data will then be transmit to a PC that connect with central node for off-line data analysis. In this thesis, we also proposed performance evaluation criterion for MAD localization system based on the error that induced by sensor array that implemented by multiple monitor nodes. The sensor array calibration method is also proposed. Finally, the simulation study is conducted based on experiment data.It is shown by the experiment results that the MAD monitor node which proposed in this thesis can detect magnetic anomaly that induced by the target. The accuracy of the signal can fulfill the requirement of localization algorithm. The linearized localization algorithm has lower computation complexity compared to its non-linear version. Furthermore, there is no additional computation error that introduced by linear algorithm. The simulation results show that the MAD target location detection system can give the location and orientation of the target in3D space with required accuracy.