Research On FPGA-Based Health Monitoring System For Typical Structure Of Aircraft’s Landing-gear

At present, the research of aircraft structure health monitoring has made some achievement,however, the health monitoring for the typical structure of landing gear are rarely studied, and thetraditional monitoring is usually based on PC for signal generation and process, in order to facilitatethe practical application, this paper presents a portable health monitoring system that can workwithout PC and a novel obliquity sensor. The design of the system adopts the combination ofhardware and software, it uses the monitoring mode of stimulation-response, which uses the specificsignal to stimulate the objects through a piezoelectric element, while receives the response signal anduses the peak value of its power spectrum as the characteristic parameters, so that the system canidentify damage in structure automatically by comparing with the healthy state, and issue a warningsignal. The obliquity sensor can achieve the measurement of object’s angle by the way that the FBGexperiences the deformation of the constant-section beam due to the change of object’s angle.Firstly, the structural health monitoring techniques and requirements for designing the system arediscussed in this paper. Then a FPGA monitoring system based on direct digital synthesis (DDS)technique is proposed, and the significance for achieving the system is explicated from differentangles. Besides, this paper analyzes the advantages and disadvantages of various obliquity sensormodel, and points out the necessity to develop and apply a new type of obliquity sensor. Subsequently,the paper analyzes the basic principles and structural characteristics of DDS for achieving an arbitrarysignal, and discusses the feasibility of using FPGA to achieve DDS.Secondly, four hardware modules of FPGA monitoring system are designed on the platform ofQuartus II9.0, including: I/O module, control module, data memory for stimulating signal module andpeak identification module. Besides, a software that generates arbitrary signal’s data for monitoring isdesigned for actual application. The software can obtain the signal data and imported it directly intoFPGA memory to achieve structure monitoring. After design work, this paper has take experimentsfor system function test and health monitoring of300M steel, results show that the system can meetthe design requirement and achieve health monitoring for typical structure of landing gear effectively.Finally, a new sensitivity adjustable fiber Bragg grating obliquity sensor is proposed for themonitoring of structure attitude angle of the landing gear, and corresponding measure system was setup to test and calibrate the sensor. The results show that the sensor can overcome the cross-sensitivitybetween temperature and strain, achieve regulation of sensitivity, and have a good performance.