【作者】 刘力；

【导师】 娄志峰；

【作者基本信息】 大连理工大学 ， 机械工程（专业学位）， 2021， 硕士

【摘要】 回转运动作为机械运动中的最基本的运动之一,其被广泛的应用在工业机器人、精密机床、激光跟踪仪、坐标测量机等。但是由于装配、制造、设计等诸多因素的存在,导致转台回转轴在运动过程中始终固有的存在着位置相关几何误差以及位置无关几何误差。误差防止法和误差补偿法是提高精密加工或测量仪器回转精度最常用的方法,相比于误差防止法,误差补偿法不需要提高零部件的制造、装配精度,通过相关理论分析建立相关的数学模型补偿误差,进一步的提升仪器的加工测量精度。所以本文着重研究转台的几何运动误差测量以及分离工作,提出转台运动误差的在线与离线测量方法,建立几何运动误差的分离补偿模型并进行测量比对验证。本文提出一种精密转台的五自由度几何运动误差的激光测量系统。基于齐次坐标变换的误差分离模型,分析参考轴与回转轴未对准的位置无关几何误差、测量仪器的安装误差、以及回转轴固有的多自由位置相关几何误差之间的几何关系。对测量的误差运动进行最小二乘圆(LSC)分析,分离出测量仪器的安装误差,同时解耦出精密转台的五自由度位置相关几何误差以及回转轴线未对准的位置无关几何误差。最后对精密转台分别进行顺时针(CW)以及逆时针(CCW)多次重复测试,并与光电自准直仪测量结果进行比对,成功验证了转台多自由度运动误差测量系统的可行性以及有效性。目前,包括上述本文提出的方法在内,转台的多自由度几何运动误差辨识大多均属于离线准静态测量。然而在实际运动过程中,回转工作台不可避免的存在着负载,由于负载的实时变化,其回转运动的多自由度的几何运动误差与离线准静态测量的误差模型不一致,导致离线准静态测量的运动误差在在线运动中补偿效果不理想。因此,本文提出一种双光栅编码器的精密转台几何误差多自由度在线测量系统,该双光栅编码器可以内嵌到精密转台回转主轴上,通过快速运动速傅里叶变换(FFT)分析回转轴的几何运动误差,成功分离出精密转台的多自由度的位置相关几何误差以及位置无关几何误差,最后通过与电感测微仪测量的工件圆度误差进行比对,验证转台多自由度运动误差在线测量系统的可行性以及有效性。最后,基于上述内嵌式双光栅的多自由度实时在线测量系统,成功设计一台具有在线自标定几何运动误差功能的精密回转运动台,其径向运动误差为±1.5μm,倾斜运动误差为±2",通过对自标定转台进行静力学分析以及模态分析,自标定转台各项性能指标符合设计需求。更多还原

【Abstract】 Rotary motion is one of the most basic motion in mechanism kinematics,which is widely applied in industrial robots,precision machine tools,laser tracker,coordinate measuring machines,etc.However,due to the assembly,manufacturing,design of rotary tables,there are always position dependent geometric errors and position independent geometric errors inherently in the rotating motion.Error prevention method and error compensation method are the most commonly used methods to improve the rotating accuracy of precision machining and measuring instruments.Compared with the error prevention method,the error compensation method does not need to improve the manufacturing and assembly accuracy of parts and components,and the related mathematical model is established through theoretical analysis to compensate for errors,and further improve the processing and measurement accuracy of the instrument.This thesis focuses on the measurement and separation of the geometric error motion of the rotary tables,puts forward to the two measurement methods on-line and off-line calibrated geometric errors of rotating motion firstly,establishes the separation and compensation model of the geometrical error motions secondly,and finally carries on the measurement comparison and verification experiment of rotary tables’ error motions.In this thesis,a laser off-line measurement system for 5-DOF geometric error motions of precious rotary tables is proposed.Based on the homogeneous coordinate transformation model,the geometric relationship between the position independent geometric errors of the misalignment between the reference axis and the rotary axis,the installation errors of the measuring instruments,and the inherent multi-degrees-of-freedom position dependent geometric errors of the rotary axis were analyzed.The least square circle(LSC)was used to analyze the measurement error motion,and the installation error of the measuring instrument is separated.Meanwhile,the five-degrees-of-freedom position dependent geometric error of the precision rotary tables and the position independent geometric error of the misalignment error of the rotary axis were decoupled.Finally,the precision rotary table was measured clockwise(CW)and counter clockwise(CCW)for several times,and the results were compared with the photoelectric autocollimator,which successfully verified the feasibility and effectiveness of the rotary table’s multi-degrees-of-freedom error motion measurement system.At present,including the methods proposed in this paper,the multiple-degrees-of-freedom geometric error motion identification of rotary table mostly belongs to off-line measurement.However,in the actual rotating motion,there is inevitably a load in the rotary tables.Due to the real-time change of the load,the position dependent geometric error motions of the rotary table were inconsistent with the model of off-line quasi-static error measurement,which leads to the error motions compensation effect of off-line quasi-static measurement is not ideal in on-line motion.Therefore,this paper proposes a multi degrees of freedom measurement system for online geometric error motion of precision rotary table with double grid discs.The dual grid discs can be embedded in the rotating spindle of precision rotary tables.The geometric error motions of grid discs were analyzed based on Fast Fourier Transform(FFT),and the M-DOF position dependent geometric errors and position independent geometric errors of precision rotary tables were successfully separated.Finally,compared with a linear variable differential transformer(LVDT)measuring the roundness errors,the feasibility and effectiveness of the on-line measurement system are verified.Based on the above-mentioned on-line multi-DOF real-time measurement system with embedded dual grid discs,a precision rotary table with on-line self-calibration of geometric error motion was successfully designed.The radial error motions are within ±1.5μm,and the tilt error motions are with ±2arcsec,Through the static analysis and modal analysis of the selfcalibration rotary table,the performance indexes of the self-calibration rotary table satisfy the designed demand.更多还原