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【摘要】：隨著自由曲面類零件在汽車制造、航空航天、造船、模具加工等許多工業(yè)領(lǐng)域的廣泛應(yīng)用,對此類零件的加工精度也提出了越來越嚴(yán)格的要求。目前,如何實現(xiàn)自由曲面零件的高效率、高精度的檢測,已成為當(dāng)前產(chǎn)品表面質(zhì)量檢測的重要研究內(nèi)容。為了獲取自由曲面的加工質(zhì)量信息,本文重點研究了自由曲面輪廓度誤差的評定模型、算法以及誤差不確定度估計方法。首先,依據(jù)形狀幾何誤差經(jīng)典定義,綜合剛體運動學(xué)中的齊次坐標(biāo)變換理論和最小區(qū)域準(zhǔn)則建立了自由曲面輪廓度誤差評定的數(shù)學(xué)模型。該模型的優(yōu)點是利用最小二乘法對測點進(jìn)行預(yù)定位處理,并將預(yù)處理后的有效測點作為精定位時的初始測量數(shù)據(jù),進(jìn)而為精定位算法的實施鎖定了高質(zhì)量的初始位姿。其次,研究了基于序列二次規(guī)劃算法(SQP)的自由曲面輪廓度誤差評定方法。針對僅已知CAD模型的曲面,提出了計算測點到自由曲面最小距離STL(STeror Lithography)模型方法;針對已知參數(shù)表達(dá)式的曲面,采用分割逼近法計算測點到該曲面的最小距離。然后,采用序列二次規(guī)劃算法,并結(jié)合距離函數(shù)的線性微分運動模型,實現(xiàn)測點與理論曲面的最佳配準(zhǔn)。此外還利用MATLAB對誤差評定算法進(jìn)行了仿真實驗,試驗的對比結(jié)果表明該輪廓度誤差評定算法的有效性。最后,分析了影響自由曲面輪廓度誤差的不確定度因素,并依據(jù)測量不確定度表示指南中的不確定度傳播律,建立了曲面輪廓度誤差不確定度估計模型。最后,通過搭建實驗平臺對上述模型和算法進(jìn)行了實驗驗證。
[Abstract]:With the wide application of free-form parts in automobile manufacture, aerospace, shipbuilding, die processing and so on, more and more strict requirements have been put forward for the machining accuracy of these parts. At present, how to realize the high efficiency and high precision detection of free-form surface parts has become an important research content of product surface quality inspection. In order to obtain machining quality information of free-form surface, the evaluation model, algorithm and error uncertainty estimation method of free-form surface contour error are studied in this paper. Firstly, according to the classical definition of shape geometric error, a mathematical model for evaluating the contour error of free-form surface is established by integrating the homogeneous coordinate transformation theory and the minimum region criterion in the kinematics of rigid body. The advantage of this model is that it uses the least square method to prelocate the measured points, and takes the pre-processed effective measuring points as the initial measurement data for precise positioning, thus locking the high quality initial pose for the implementation of the precision localization algorithm. Secondly, a method for evaluating the contour error of free surface based on sequential quadratic programming (SQP) is studied. For the surface with only known CAD model, a STL (STeror Lithography) model method is proposed to calculate the minimum distance from the measuring point to the free surface, and the partition approximation method is used to calculate the minimum distance from the measured point to the surface for the surface with known parametric expressions. Then, using the sequential quadratic programming algorithm and the linear differential motion model of the distance function, the optimal registration between the measured points and the theoretical surface is realized. In addition, the error evaluation algorithm is simulated by MATLAB, and the comparison results show that the algorithm is effective. Finally, the factors of uncertainty affecting the contour error of free-form surface are analyzed, and a model for estimating the uncertainty of contour error of curved surface is established according to the uncertainty propagation law in the guide to express the uncertainty of measurement. Finally, the above models and algorithms are verified by building an experimental platform.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TP391.72;O186.11

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本文編號：2414329