Research On Aerospace Special Valve Spool Assembly Based On One-Dimensional Force Sensing

The special solenoid valve is one of the key components which used for flow control in space propulsion to ensure the smooth implementation of space missions.The valve core is the core component of this type of special solenoid valve.It has small length/diameter ratio points with short shaft length and large diameter.It is required to perform micro-scale gap assembly with the valve body with deep hole structure.At present,this type of spool assembly relies on manual work,which not only requires extensive assembly experience,but also has poor assembly consistency and low efficiency.Therefore,this topic is aimed at the automatic assembly requirements of aerospace special high-precision solenoid valve spools,and abstracts the micro-gap ultra-short axis deep-hole assembly as the research object.It studies from the three aspects of assembly system,hole-seeking strategy and instrumentation method.The composite compliant peg-in-hole assembly method of the force sensing and flexible clamping operation hand,and verified by experiments that the method meets the automatic assembly of the aerospace special high precision solenoid valve spool.The main research contents of this paper are as follows:1)A composite compliant peg-in-hole assembly method based on one-dimensional force sensing and flexible clamping operation is proposed,which is designed for the small length-to-diameter ratio ultra-short shaft deep hole assembly of aerospace special high-precision solenoid valve spool.Five functional modules of motion,adjustment,force sensing,and system control.2)According to the requirements of ultra-short axis assembly positioning,the active hole-seeking strategy based on one-dimensional force sensing is studied.Through the modeling and mechanical analysis of the contact state of the hole seeking,the hole spacing of the peg-in-hole is reduced,and the pressure of the end face of the peg-in-hole is attenuated.According to the law of force variation,an active hole-seeking control algorithm based on one-dimensional force sensing is designed to solve the hole-seeking problem of small length/diameter ratio ultra-short axis deep hole assembly.The algorithm combines the characteristics of adaptive deformation of flexible working hands,and solves the problem of finding holes in the micro-gap non-chamfered peg-in-hole assembly based on only one Z-direction force information.3)In order to solve the ultra-short shaft deep hole insertion,analyze the instrumentation process of ultra-short peg-in-hole assembly,and construct the mechanical model of each state of each stage of the insertion and loading.The simulation analysis shows that the larger the deviation of the end position is,the insertion force The larger the force fluctuation is,the higher the probability that the initial insertion depth is delayed and the hole cannot be inserted.Through the system,the limit conditions for successfully completing the insertion of the jamming resistance are as follows:the end position deviation is 0,3 mm,the adsorption deviation is 0.5 mm,and the initial insertion depth is 0.15 mm.The maximum insertion force at this time is 8.9 N,which is smooth.Cartridge.4)In order to verify the feasibility of the assembly method,the assembly experiment system integration is first completed,and then the influence of various parameters on the assembly effect is studied.After the parameters are optimized,the smooth assembly is achieved.At this time,the initial position deviation is less than 4 mm,and the initial hole seeking pressure is 0.4.Between-0.6N,the insertion speed is less than 4mm/s,and the insertion force threshold is less than ION.The overall experimental results show that the precision peg-in-hole assembly method based on one-dimensional force sensing meets the aerospace special valve spool assembly with a diameter of 20 mm and a radius gap of 3μm.