Research On Redundancy Control Of Nose Wheel System For An Aircraft Landing Gear

With the fast development of digital and information technology, digital fly-by-wire system has gained obvious advantages in calculation of flight control law, redundancy management, and logical judgment, etc. Thus, flight control system of many newly-made foreign aircraft has widely adopted digital fly-by-wire system. After upgrading a certain aircraft landing gear with digital fly-by-wire technology, the main focus of this paper is redundancy control and built-in-test technology of Nose wheel steering system.In this paper,relationship between redundancy structures and system reliability have been researched using redundancy and reliability theories.Based on these analysis,the system redundancy structure have been proposed; the design of sensors, hydraulic, electric control and BIT subsystems are accomplished. According to high reliability and testability requirements for avionic electronics products, using redundancy control and BIT technology, a type of landing gear steering controller was designed,which is based on treble-redundancy dissimilar cold backup architecture.Then the hardware and software design of dual-DSP channel,PLC channel and redundancy management and detection channel are accomplished. Reliability model of treble-redundancy landing gear steering controller is developed based on markov process. It is proved by the reliability simulation results that this controller has higher reliability than previous single redundancy controller.The steering experiment platform of landing gear is established, on which the following experiments are performed:verification experiment of analog input and output of PLC channel, verification experiment of steering control law and verification experiment of BIT function. The results show that the PLC channel has the ability and accuracy of steering operation; the performance of controller in two steering mode can meet the relative requirement of error; the treble-redundancy controller has good performance of status monitoring, fault diagnosis, redundancy management and system reconfiguration.In conclusion, the designed steering control system can meet the basic requirement of an aircraft landing gear.