Research On Vibration Characteristics And Control Strategy Of Robotic Drilling System Of Elastic Components

The robot drilling system of elastic component is a coupling system composed of industrial robots,drilling actuators and elastic components.Due to the low stiffness of the open-chain multi-degree of freedom series robot body,vibration is easy to occur in the drilling process.At the same time,the elastic component is prone to chatter under the action of drilling force.The elastic vibration of the elastic component through the coupling of the drilling spindle and the robot body affects the stability of the robot drilling system and the quality of the drilling of the elastic component.In this paper,vibration characteristics and control strategies of robot drilling system with elastic components are studied.The main research contents are as follows:First,combined with the structure of the robot drilling system,the axial stiffness characteristics of the robot drilling system were analyzed.The kinematic model of the robot was established by using D-H parameter method.The equivalent model of the axial stiffness of the robot was established based on the kinematic model and the differential transformation method.The equivalent model of the axial stiffness of the elastic component was obtained by force analysis.By using theoretical analysis,finite element simulation and experimental test,the axial stiffness characteristics of the robot and the elastic member in drilling direction were analyzed,and the distribution law of the axial stiffness of the robot and the elastic member was verified,which provided the basis for the dynamic analysis and vibration control of the robot drilling system.Secondly,considering the dynamic coupling effect of robot,drilling device and elastic component in machining process,the equivalent dynamic model of mass-spring-damping system of robot drilling system was established.In view of the complex coupling relationship of robot structure,it is difficult to obtain modal parameters in theoretical analysis.Therefore,the modal parameter data of robot and elastic component were obtained based on virtual prototype experiment.Through virtual prototype simulation data and theoretical model,the influences of different compression forces and stiffness on the vibration characteristics of robot drilling system were analyzed.Then,by designing the active and passive vibration control strategy of the robot drilling system with elastic components,the vibration between the robot and the elastic components is reduced by adding a passive vibration isolation device when the end of the robot drilling device contacts with the workpiece.At the same time,the active control of the elastic vibration of the drilling system is realized through the pressure force servo control of the drilling device.The effectiveness of the active and passive vibration control strategy is verified by ADAMS and MATLAB/Sim-ulink co-simulation.Finally,on the basis of theoretical analysis and virtual prototype simulation,the end effector of active and passive drilling of elastic component robot drilling is designed and developed,including spindle drilling feed system,pneumatic compaction system and active and passive vibration reduction system.The hardware equipment selection,processing and assembly,control system and upper computer program design of the end actuator prototype were completed.Based on the hardware and software of the prototype and control system,an experimental system for robot drilling of elastic components was built.By comparing the conditions,the experimental testing of robot drilling of elastic components was completed,and the active and passive vibration control effect of the robot drilling system of elastic components was verified.