Research On Static Deformation Of The Arm Of Self-driving Articulated Arm Coordinate Measuring Machine

With the development of automation and intelligence in the manufacturing industry,the accuracy and efficiency of online measurement are becoming higher and higher in the production process.There is an increasing demand for measurement of large workpieces,especially irregular shape workpieces.Coordinate measuring machines are an important way to solve this demand.The articulated arm coordinate measuring machine is applied due to its flexible operation and easy manipulation.Because of its relatively complicated structure,the source of error is not single,and the measurement error,especially the measurement error of the self-driven articulated arm coordinate measuring machine,is relatively small,and it is difficult to meet the actual demand for further improving the processing quality of the product.It is urgent to carry out research in this aspect.In this thesis,the self-driven articulated arm coordinate measuring machine is taken as the research object.The combination of theoretical analysis,simulation and experiment is used to systematically study the influence of the deformation of the arm on the accuracy of the articulated arm coordinate measuring machine.The main work and research results are as follows:(1)In order to establish the mathematical model of the articulated arm coordinate measuring machine,the paper compares the characteristics of DH model,Hayati improved DH model,MD-H model and spin volume exponential product model.The spin volume exponential product is selected as the self-driven articulated arm coordinate measuring machine.The modeling tool establishes a mathematical model of coordinate measurement based on the spin volume exponential product,which provides a theoretical basis for the accuracy analysis of the articulated arm coordinate measuring machine.(2)Ideally,the self-driving articulated arm coordinate measuring machine can be regarded as a rigid body,and the relative rotation angle between the two arms of the joint is detected by the disk grating sensor at each joint,and the mathematical model is used to obtain the Cartesian coordinates with the base as the origin.End probe position information.For the actual self-driving articulated arm coordinate measuring machine,the self-weight causes the arm to elastically deform,causing the end probe to deviate from the ideal position,resulting in measurement errors.Based on the principle of virtual work,the translation method of joint force and the relationship between the attitude of the measuring machine and the mechanical deformation are used to establish the deformation model of the self-driven articulated arm coordinate measuring machine,and the calculation method of the force deformation error is solved.(3)A self-driven articulated arm coordinate measurement test prototype was designed and developed,and a new method based on fiber grating strain sensing technology for boom deformation detection was proposed.Under the combined action of axial force,radial force,bending moment and torque,six axially bonded fiber grating strain sensors and an obliquely bonded fiber grating strain sensor on the outer side of the arm are used to measure the strain.Analysis,to achieve separation and detection of the composite load of the boom.The measured load is substituted into the deformed body model to obtain the measurement error.The experimental results show that the monitoring method is accurate and reasonable,and can accurately and accurately describe the static error law of the articulated arm coordinate measuring machine,which provides theoretical basis and practical experience for the subsequent research.Figure [59] table [23] reference [50].