Research On The Design And Characteristic Analysis Of Precise Cable Drive System

Precise cable drive is an elegantly simple technology,with a flexible layout,lightweight,miniaturization and other characteristics.It is widely used in precise acquiring tracking and pointing system(ATP),human-robot interaction equipment,biped or quadruped robot,terminal operating equipment and other systems.However,there are still some problems in the precise cable drive,which restrict it applied in high-precision and high-dynamic occasions.For example,the effect of force displacement characteristics and the mode of transformation are not well understood.The mapping relationship among design parameters,transmission characteristics and servo performance is not clear.Design theory is not systematic and normative.Focusing on the problems,the dynamic and static characteristics of transmission and the design method are studied in this paper.Through the research of these basic theories and key technologies,the genetic mechanism of the characteristics of the precise cable drive is mastered,and the standardized engineering design method is established,which lays a foundation for the application of the flexible cable drive in the precise servo mechanism.The main content includes the following parts:1.The design of high-performance precise cable drive components depends on the understanding of the transmission characteristics.Aiming at the problem that the creation mechanism and evolution rule of static characteristics of transmission are not fully understood,the theory and simulation model of transmission stiffness,hysteresis characteristics and transmission backlash of precise cable drive are established.Then the accuracy of the theoretical model is fully verified through experiments.The overall fitting degree between the theory and test results is over 85%.Through the above research,we draw the following conclusions: transmission stiffness presents the softing-spring characteristics.It indicates that the cable drive is suitable for the application of small load.The hysteresis characteristic not only depends on the loading moment at that time,but also is affected by the course of external load.The friction torque in the system should be reduced as much as possible.The generation and change rules of key static characteristics of cable transmission are comprehensively mastered.2.The dynamic characteristics of transmission components directly affect the servo performance of the system.Mechanical resonance and friction disturbance are two key dynamic factors that restrict the improvement of the performance of the precise cable drive servo system.Friction disturbance will cause static error and low speed jitter in the system.In order to master the control principle of the performance of the flexible cable drive servo system,the dynamic model of the double inertia elastic system was established.The causes of the mechanical resonance of the system and the law of the influence of the parameters on it were studied.The frequency identification method is used to identify the parameters,and the state extended kalman filter is constructed to observe and compensate the friction disturbance.The experimental results show that the proposed method can obviously improve the speed of the zero friction compensation dead zone and low jitter phenomenon.The dynamics of the established model can accurately predict the mechanical resonance center frequency,using the proposed notch filter control strategy,can effectively suppress the internal state of oscillation.The speed response error is decreased by more than 90%.Thus,the mapping relation between response precision and key dynamic characteristics is clarified,and the servo performance of the system is improved.3.Precise cable drive has typical characteristics of customized design.Its layout and preload mode are closely related to host structure and load characteristics,making it difficult for the design theory of flexible cable transmission to achieve systematic standardization.In view of the lack of modular design method,the engineering design process of the flexible cable drive mechanism is proposed,and the key steps are studied.Pretension is one of important design parameters which could regulate the transmission characteristics effectively.However,it is hard to measure accurately by the existing tension meter method in highly confined spaces.Therefore,a revised Three-PointBending method was proposed in this paper.The cable tension measurement revised model including the bending rigidity was established.The test results show that the tension deviation could narrow down to 5N by using proposed method,which was greatly reduced compared with existing method reported in the literature.It can meet the cable tension measurement requirement of precise cable drive system.In addition,in view of the difficulty in directly adopting mathematical analysis method to describe the complex cable-drive system with complex configurations,a rigid-flexible coupling finite element simulation method based on RecurDyn was proposed.It can be used to analyze the tension variation of each micro-segment of the flexible cable,providing an effective means for analyzing the characteristics of the complex cable-drive mechanism.Through the above research,the specific process and relevant criteria of precise cable drive engineering design are systematically put forward.4.Precision rotary electromechanical actuator is the base unit in the solar panels,the antenna pointing systems.The servo accuracy,output torque,the overall quality,the moving distance and other technical indicators,put forward the stringent requirements to its.Traditional way of gear and motor direct driving drive hard to at the same time satisfy the requirements above.Aiming at the application requirements of lightweight high-precision drive components,a transmission configuration based on the combination of bevel gears and guide gear train is proposed in this paper,and the kinematics relationship and the characteristics of the transmission air-to-air cycle under this configuration are studied.The experimental results show that the output torque of the prototype is up to 3.3 N·m,the output torque density is up to 9.649 N·m/Kg,and the position follow-up precision is about ±0.3mrad.Aimed at the application requirement of high torque ultra-high precision drive components,this paper proposes a multiple input single output(MISO)class straight gear flexible transmission configuration,studied the configuration of the transmission capacity,stiffness and returned empty transmission characteristics,such as the experimental results show that the prototype can be output torque and 35 N·m,output torque density up to 8.997 N·m/Kg,motion resolution can be better than the 0.5?rad.Both of the above two principle prototypes have achieved the expected design goal.It indicates that the design methods of the otary electromechanical actuator based on the precise cable drive are formed.5.Ball screw as the common drive element is used in the linear module,which is widely used in various industrial equipment and precision instruments.This paper proposes a linear transmission configuration based on combining guide wheel with movable pulley configuration.Then the design process methods based on linear transmission configuration is studied.As the cable on the driving wheel can lead to transmission failure in this configuration,the mapping model of design parameters on the inclined angle was deduced.At last,the experimental prototype is manufactured.Experimental results show that: the effective stroke of the prototype is 200 mm,the maximum speed can reach 1m/s,the positioning error can be better than 2.44 ?m.The results show that the precise cable drive technology can meet the high speed and high precision requirements of linear module.The design methods of linear module based on precise cable drive are formed.