Research On Cable-drive Seeker Mechanism

Precision strike has become one of the important ways and means of firepower competition in the modern warfare.As a key component of precision strike weapons, Seeker is to track the targer fast and accurately.Aiming accuracy of seeker has a great impact on success rate of missile attacking the target. Gyro stabilized platform is required to isolate the line of sight (LOS) from the movement and disturbance of carrier and ensure pointing and tracking for target in electro-optical tracking system.With the development of Electro-Optical interference technology,it is difficult for single-mode seeker to detect and track the target comprehensively on the more and more complex battlefield combat environment,Multi-mode combined control and guide will be future mode of precision guided weapons,the structure of seeker will become more small,more lightweight and design for multi-mode. Those put forward higher requirements to the platform structure and performance of transmission mechanism, simple, lightweight, hight-efficient, high-precision and integration is the basic requirements for new style seeker.Basd on cable drive arc gimbal seeker,in the article,two aspects are studied:The first is Research on transmission principle and transmission properties of cable drive.In this part,related design problems about cable drive are solved.Various factors impacting the transmission performance and accuracy of cable drive are analyzed.High stiffness, high precision and high efficiency of cable drive are verified. The second is about a new style seeker platform based on cable drive.Dynamics of coupling system as well as decoupling control of cable drive arc gimbal are analyzed and studied.The main work is organized as follows:1. Basic cable drive form and transmission theory. Those study are about capstan design, cable selection, cable wrapping, cable tensioning design ect. Cable-driven accuracy and error are deduced.At the same time, some experimental about transmission accuracy, error and miniature steel rope elastic model are verified.The results show that:accuracy of cable dirve is related with rope material, cable preload and friction as well as machining accuracy of capstan. Axial movement along rotary shaft is the characteristic of cable drive. So correct matching axial cable travel is the key factor for cable drive.Under the correct matching rope groove, cable drive can get to micro-level positioning accuracy.The transmission errors consist of the low frequency components.2. Dynamic studying on cable drive. Transverse vibration of rope as an axially moving string and transmission stiffness of cable drive are studied. Some factors affect Transmission stiffness of cable drive are simulated and analyzed. Some experiments show the theory about stiffness is correct.The results show that:Transmission stiffness of cable drive is fitted with an exponential function.It is related with preload, load, cable groups, friction.Different load, different transmission structure and parameter.3. A new style seeker platform based on cable drive is proposed. Structural characteristics of seeker are anylazed.dynamic equations of seeker platform are deduced.The results show that:there is strong torque coupling between inner gimbal and outer gimbal.coupling degree shows that system is unstable without regard to control system.so it is necessary for seeker coupling system to decouple.4. Decouling control of coupling seeker system is studied. Aiming at many different Line of sight (LOS) stabilization modes, Decoupling control methods are brought forward. Torque Disturbance observer (TDO) is applied to decouple strong torque coupling system in velcocity loop for velocity-Stabilized mode seeker. Active Disturbance Rejection Controller (ADRC) with feedforward decoupling control is applied in position loop for positon-stabilization mode seeker. Cross-coupled controller is applied to reduce the pitch position error of multiple motor positon coordinated control.The results show that:with good robustness and decoupling performance,TDO and ADRC can not only solve coupling object model uncertainty, but also realize coupling system high precision and high performance. Each is suitable to strong torque coupling control. At the same time, the pitch error is minimized through coordinated motion.