Research On Improved Local Area Differential GPS Method For Deformation Monitoring Based On ZigBee

It is meaningful to precaution the disasters such as dam break and public building collapse that the research on deformation monitoring. Comparison to traditional methods of deformation monitoring such as manual operation,optical fiber sensing and laser positioning,local area differential GPS(LADGPS) method have predominant advantages. However,there are several drawbacks in LADGPS method of deformation monitoring,for instance,single parameter of point displacement and requirement of special data link.To solve the drawbacks in LADGPS method,improved method combined LADGPS with wireless sensor network(WSN) is presented in the paper.In improved LADGPS method,special data link of LADGPS method is replaced by WSN,that decreases inconvenience caused by cables or powerful wireless transmitter.And more ambient parameters such as temperature are added to measure for analyzing the relationship between deformation and ambient parameters.According to the relationship,a mathematic model,involving the principle and solution method is presented.Experimental facility is set up for demonstration of improved LADGPS method,and main framework of experimental facility is CC2431ZDK,which is a Zigbee standard WSN development kit produced by TI Corporation.In experimental facility,GPS 15L which is receiver module produced by GARMIN Corporation is integrated into CC2431ZDK nodes as displacement sensor of monitoring points. Fundamental of improved LADGPS method is relative differential GPS (RDGPS),which is suitable for deformation monitoring rather than absolute differential GPS(ADGPS).Carrier phases and pseudo-range datum for resolving displacement of monitoring points are acquired by GPS15L,and ambient temperature datum of monitoring points is gathered by temperature sensor aboard CC2431ZDK node.All data are transmitted to personal computer(PC) via collection node through 2.4GHz wireless link of WSN.Acceptance,analysis,display,storage and processing of all data are implemented by Labview software on PC.It is an advisable and effective method of deformation monitoring that improved LADGPS with WSN is demonstrated in multiple experiments.But due to multi-path interference,differences between receivers and clock drift,there are subsequent optimal process on measurement accuracy for improved LADGPS method of deformation monitoring.