Development Of Precision Assembly System For Wire Suspended Pendulum Accelerometer Base Component

The suspended wire pendant accelerometer is an important part of the inertial navigation and guidance device in the field of aerospace.It measures the acceleration of the carrier,and its assembly belongs to the category of precision assembly.At present,it still relies on the manual assembly of the operator,who uses tweezers to assemble under a magnifying glass and a microscope.Low degree of automation,poor product consistency,small room for capacity improvement and difficult to trace key assembly parameters and product quality.In addition,precision assembly requires high skills of operators,high labor intensity and poor substitutability,so it is urgent to develop an automatic assembly system and carry out research on the automatic assembly technology of each component in the suspended wire pendulous accelerometer.Based on the analysis of assembly tasks and technical requirements,the automatic assembly system of accelerometer base component was developed in this paper.The assembly of suspended wire pendulum component was put on the seat,then the suspended wire was tensified,and the two ends of the suspended wire were automatically welded to the column of the seat.The assembly process needs to control the gap between the inner ring of the hanging wire pendulum assembly and the magnetic steel side,the height of the hanging wire from the reference level of the accelerometer base,the tension force of the hanging wire and the welding temperature.Reference manual assembly process and experience to dismantling of assembly tasks,based on modular design,the suspension wire pendulum accelerometer automatic assembly system is divided into five modules: visual measurement module,assembly operation module,workbench module,suspension wire tension module and welding module,the design of mechanical structure of the assembly system,and according to the functions and features of different modules,the design of hardware structure and function of the corresponding module to realize the control strategy.In order to ensure the accuracy of the assembly,appropriate industrial cameras and telecentric lenses are selected for the key purchased parts of the equipment.Meanwhile,appropriate lighting conditions are provided with annular light source and coaxial light source to jointly constitute the visual system.The precision mobile sliding table with repeated positioning accuracy of ±2?m was selected to build the three-degree-of-freedom assembly operation module.In order to prevent the damage of pendulum components in the operation process,the force sensor was integrated on the manipulator arm of the assembly operation module to detect the assembly force in real time.In the assembly process,the pendulum component and the base should move in coordination to ensure that the vortex plate of the pendulum component does not interfere with the base column in the assembly process.Therefore,the workbench module with three degrees of freedom is designed to fix the base,and the assembly work module is used to complete the assembly of the pendulum component.According to different force control requirements and temperature control range,reasonable force sensors and temperature sensors are selected.In order to meet the assembly accuracy,the camera pixels and force sensors in the system were calibrated first,and then the assembly experiment of the accelerometer base component was carried out.The assembly process was developed,and the errors generated in the assembly process were analyzed,and the corresponding compensation method was proposed.The experimental results show that the assembly system of suspended wire pendant accelerometer base assembly can complete all assembly tasks,and the clearance between the inner ring of pendant assembly and the magnetic steel side can be controlled within the range of 1.0±0.1mm,and the assembly results can meet the requirements of relevant technical indexes.