Design And Analysis Of Differential Cable-driven Inertially Stabilized Platform

The photoelectric stabilized platform takes the photoelectric detection device as the payload,and under the control instruction,the disturbance on optical axis caused by the motion of the carrier can be compensated by the multi-axis motion.On the basis of keeping the inertia stabilization,it can further achieve the search,capture,tracking and positioning of the target,which is widely used in airborne,missile,carrier-based and vehicle-mounted equipment systems.In order to guarantee higher stability precision,torque motors are generally employed to drive the integrated gimbal frames of the photoelectric stabilized platform directly.This leads to a lower load/self-weight ratio and makes it difficult to meet the requirement of lightweight and high precision simultaneously.And the new battlefield environment gave birth to new application requirements,the light-weighted carriers like the Unmanned Aerial Vehicle(UAV)in the future put forward higher demands,which makes the contradiction more prominent.In this thesis,the traditional structure of the two-axis and two-gimbals platform is replaced by the differential form innovatively,realizing the parallel drive of motors.And the cable-driven transmission with the advantage of low transmission error,high stiffness,high efficiency and no need to lubricate is introduced in mechanical system design instead.The work above not only improves the load/self-weight ratio of the platform effectively,but resolves the conflict of compact design and suitability enhancement,which makes the platform meets the requirements of large load capacity,lightweight,high precision,wide adaptation and compact structure.The research effort of the paper is mainly reflected in the following aspects:The overall structure and control technology are studied based on the functional requirements and technical indexes of the platform.Based on the analysis of the mechanism and the basic transmission configuration of the flexible cable,a new configuration of differential cable-driven transmission is proposed with the sufficient study on the transmission principle and basic transmission configuration.And its working principle is further demonstrated.Research on the key characteristics of the cable-driven differential configuration platform.To explore the key mechanical factors influencing the transmission precision,the transmission model including ropes is established,and the backlash characteristic of the whole machine are analyzed.Then its kinematic characteristics and the dynamic transmission characteristics are lucubrated.In addition,the simulation method of flexible body is studied.The flexible-body drive characteristics simulation and whole system simulation are achieved based on ADAMS.Research on the method of mechanical structure design and optimization.The method of load analysis and structural design are studied to guide the selection and verification of key elements like the wirerope and motors.The structure optimization of important components is guided by the intensity check and modal analysis.Finally the scheme of detailed structural design is formed.Research on dynamic modeling and decoupling method of multi-input and multioutput system with strong coupling.To analyze its dynamic characteristics,the dynamic model of system is established by means of analytical mechanics.The coupling characteristic is quantitatively described and analyzed by Coupling Degree.The decoupling control method is studied and the decoupling strategy is also proposed to provide reference for the control system design.The system is set up to carry out transmission performance test.The results show that the prototype can meet the requirements in weight,stoke and load capacity with load/self-weight ratio improved significantly.And the expected function is realized with good dynamic characteristics.