Design And Reliability Analysis Of A Aircraft Landing Gear Control System

Landing gears play a pivotal role for aircrafts to take off and land safely. Traditionalcentralized landing gear control systems can not meet the needs of development becauseof its heavy wire harness, relatively low reliability and poor real-time performance, soreal-time distributed control system came into being. Distributed control strategy hasmany features including: modularity, scalability, etc, and the control system uses the buscommunication technology, which greatly improves its timeliness and reliability.A distributed aircraft landing gear control system based on TTCAN protocol isdesigned in this paper. The reliability and network performance of the control system isanalyzed, and the results show that designed distributed control system has goodreliability and timeliness. Electrical control system of aircraft landing gear is mainlystudied in this paper. Star–bus mixed topology is used, which not only makes it wiringsimple and scalable, but also improves the ability of fault detection and handling. Thelanding gear distributed control system consists of three subsystems: the nose landinggear, the left main landing gear and the right main landing gear. There are many controlunits and associated sensors and actuators that achieve a decentralized control andcentralized management of nodes. Sensors, actuators, control units and buses of systemsare redundant and it greatly improves the system reliability. TTCAN interface module isconnected to TTCAN bus in each landing gear node, to complete the transfer of databetween the various parts of the control system by design of hardware, software and thesystem matrix. Finally, a semi-distributed power scheme is designed for thiscommunication architecture of control system.The reliability of the control system is analyzed using fault tree and Markov model.the main fault tree model is studied in fault tree analysis，and the probability of failure iscalculated by the minimal cut set method. Markov state space diagram is gave inMarkov model analysis, and system reliability is calculated by Markov solving process. Real-time of system is essential for the design of distributed control systems. Delayperformance of TTCAN network is simulated by OPNET software, and network delayis studied by building the network model, node model, process model. The result showsthat TTCAN network delay is very small, and it is a field bus that has a good real-timeperformance. The designed control system can meet real-time requirement of aircraftlanding gear control system.A distributed aircraft landing gear control system based on TTCAN protocol isdesigned in the paper. The designed system reduces wiring complexity and weight, itsreliability is very high, and it has a good real-time performance, which is of greatsignificance for improving the safety and economy of landing gear retraction/extensioncontrol system.