Research And Design Of Windshield Wipers Control System For A Certain Helicopter

The wind shield rain removal system is of great significance for aircraft to ensure its flight safety,and currently windshield wiper is widely applied to the wind shield rain removal system.Under this background,this thesis takes the reliability improvements of windshield wiper device as the design objective,and combining with practical work experience,the author takes the windshield wiper device of a certain helicopter as the research object to conduct the research and design of its windshield wiper device control system.This thesis mainly includes four parts as follows.Firstly,the author explores the conceptual design of the windshield wiper device control system.After a brief introduction of the windshield wiper device system,the author proposes three kinds of motor schemes and determines to use the brushless DC motor as the driving part of the helicopter windshield wiper device with a comparative analysis.Then two feasible plans for control circuit are designed and the hardware circuit scheme with higher reliability is selected.Finally,MC33035 is determined to be the motor driver and MC33039 is determined to be the speed regulator to improve the conceptual design,which also lays a foundation for the subsequent hardware design of the windshield wiper device control system.Secondly,the author explores the hardware design of the windshield wiper device control system.With a theoretical analysis of the relevant structure components of the windshield wiper device,the author firstly determines the parameters of the brushless DC motor.Then,the author explores the hardware design of the windshield wiper device control system in Altium Designer platform.Based on the above designed hardware circuit,the author conducts a modularization analysis to discuss the feasibility of the separate circuit module,which is,respectively,command module,power module,speed closed-loop module,motor drive module,protection module and etc.Furthermore,PCB design and hardware testing are carried out,and electrical parameters are optimized according to the test results.Thirdly,based on the designed hardware circuit and the structure components of windshield wiper device,the comprehensive reliability analysis of windshield wiper device system is carried out and further proved by reliability test.The author firstly develops the basic reliability mathematical model of windshield wiper device,then analyzes the reliability prediction of each component of windshield wiper device system.Specifically,the reliability prediction of motor components is analyzed by "components counting" method,while the reliability prediction of structure components is analyzed by "similar products" method to calculate the failure rate of the separate component.Finally,the obtained reliability and mean time between failures(MTBF)satisfy the MTBF regulation value.For further verification,the author develops the reliability compliance test.With the issues occurred to be analyzed and corrected,the reliability of windshield wiper device is further improved.Finally,the electromagnetic compatibility(EMC)for the wiper system is designed and further verified by EMC test.The author firstly briefly introduces the basic theory for electromagnetic compatibility,then followed by the unique characteristics of windshield wiper device of a certain helicopter,the author designs the electromagnetic compatibility from the aspects of PCB board,grounding,shielding and filter according the effective technology.Finally,after the verification and adjustment by EMC test,EMC trial items,namely CE101(the issues occurred to be analyzed and corrected),CE102 and RE102,all meet the relevant requirements of GIB151B.