Study On The Principle And Design Method Of The Precise Cable Drive

Precise acquiring tracking and pointing system(ATP) is playing a more and more important role in modern military reconnaissance and fire control, precision-guided weapons systems, space exploration engineering, industrial and medical equipment, and other national defense and economic issues. A brief overview of previously built acquiring tracking and pointing devices reveals a trend toward smaller, more agile systems. However, the traditional transmission method including gear drive, chain drive and belt drive and other traditional methods has been difficult to meet these requirements. It is urgently to explore a new transmission method with higher transmission accuracy and dynamic response characteristics. Therefore, purpose of this thesis focuses on the development of the new precise cable drive technology, including the transmission mechanism, characteristic analysis method, performance simulation, experimental verification and other issues. The design and characteristic analysis method of precise cable drive is put forward. The precise cable drive technology is used in two typical ATP applications to verify the theory of precise cable drive. Work in this thesis could provide a technical support for the application of the precise cable drive in new generation of high-precision and lightweight ATP systems.The following studies are included in the thesis:1. In order to master the impact of the transmission factors on the servo control performance, the modeling and analyzing method of the transmission stiffness, backlash and transmission friction are studied in detail. The improvement of servo performance includes advantage control method and new transmission method. Study on a new transmission mode with higher transmission accuracy and dynamic response is urgently to improve the performance of ATP system.2. In order to explain the principle and design method of the precise cable drive, the typical configuration and work characteristics is analyzed and a number of key design issues are summarized. The cable-drum interaction is discussed in detail and the effect of bending stiffness and nonlinear friction on the tension ratio is investigated. A non-intervene cable wrapping method is presented to decrease the wear between the incoming cable and outgoing cable and decrease the scrubbing between the cable and groove. The typical failure modes of precise cable drive are discussed, the design guidance and general procedures of precise cable drive for typical application is provided.3. The transmission characteristics of precise cable drive are researched, including the transmission capacity, transmission backlash, transmission stiffness, longitudinal vibration and lateral vibration. The theoretical formula is deduced and the relationship between the design parameters and the transmission characteristics are investigated. The experimental setup of precise cable drive is built and the effective modulus of cable, cable-drum frictional coefficient, and transmission backlash is tested to verify the correctness of the theoretical formula. The design and characteristic prediction method has been initially come into being.4. In order to analyze the characteristics of complex cable drive system, A simulation method based on Recurdyn software is presented. The rigid-flexible hybrid modeling method of cable is studied. The simulation method based on Recurdyn software is developed, including the modeling of the cable with bushing force, the parameter calculation method of bushing force, and the modeling of the cable-drum interaction with rigid-rigid contact. The simulation model of precise cable drive is built and the transmission capacity and transmission accuracy is simulated to verify the simulation method.5. According to the requirement of strict size, weight, and high precision, the precise cable drive technology is used in an ultra-light optical pod. The background and the technical indicator is discussed. The precept of precise cable drive ultra-light optical pod is discussed and the characterization design methods are studied. The ultra-light optical pod experimental prototype is built, and the relevant performances are tested. The results show that the precise cable drive ultra-light optical pod has a better transmission performance, and high positioning accuracy can be achieved.6. According to the requirement of large field of view, light weight and high precision for a new generation seeker, a diffential cable drive mechanism is presented. The mechanical design, including structure configuration, transmission system and feathers, kinetic principle is introduced. Dynamics of the differential cable drive mechanism is studied based on the Lagrange equations and simulation method based on Recurdyn. Experimental setup is built, and the frequency response in different operating conditions is investigated and the transmission performance is tested. The location tracking accuracy is tested based on the PID+DOB decoupling controller. These application examples could better demonstrate the feasibility of precise cable drive in ATP system, which could also provide a reference for further applications.