微小型加速度计磁钢组件自动装配设备研制

发布时间：2018-10-09 16:56

【摘要】：加速度计是惯性导航系统的重要组成部分,是一种典型的微小型机电产品,其性能直接影响导航精度。而加速度计力矩器磁钢组件装配质量会影响加速度计的线性度,从而影响加速度计性能。目前加速度计磁钢组件的装配主要依靠手工操作完成,装配效率低、精度差,依赖装配人员的技能,产品一致性差。迫切需要研制自动装配设备,应用高精度自动装配技术来解决这一问题。本文针对某型号微小型加速度计的磁钢组件装配任务,研制开发了基于机器视觉的精密自动装配设备。设备采用模块化设计思想,分为视觉测量模块、装配作业模块、作业工作台模块和装配控制模块。视觉测量模块用于获取零件的位置和姿态信启、：装配作业模块完成零件的拾取、移动和装配等任务：作业工作台模块提供装配空间,其中夹具实现零件的装夹和装配后的固定等功能：装配控制模块控制设备其它模块有序的工作,并提供人机交互界面。根据壳体和磁钢零件特征设计了零件操作装置和夹具,保证了装配过程的稳定性,提高了装配精度,并实现了对装配力的实时检测和控制。视觉测量是一种非接触测量方法,测量速度快,不损伤零件,为了提高视觉测量的精度和效率,开发了一种基于图像灰度值的粗精结合的自动对焦算法,粗精两个阶段分别采用方差函数和梯度方差函数作为图像清晰度评价函数,采用爬山法和二次插值法搜索最优解。并根据磁钢和壳体零件特征设置光照环境,保证了磁钢和壳体零件上表面的图像采集质量。使用中值滤波、线性灰度增强对图像进行预处理,提高其识别精度。基于图像拼接技术扩大了大倍率相机的采集范围,最后提取边缘点并利用最小二乘法拟合圆,完成了零件的测量任务,得到待装配零件的特征点位置信息。分析了影响装配精度的主要因素,基于齐次坐标转换建立了误差补偿模型,标定了图像坐标系、视觉测量坐标系和装配作业坐标系之间的夹角,并对三维运动平台各轴之间的垂直度误差进行了补偿。经过装配实验验证,装配精度能够达到10μm,符合设计要求,装配稳定性、一致性等均满足预期要求。
[Abstract]:Accelerometer is an important part of inertial navigation system. It is a typical micro electromechanical product. Its performance directly affects navigation accuracy. The assembly quality of accelerometer torque magnets will affect the linearity of accelerometers and thus the performance of accelerometers. At present, the assembly of accelerometer magnetic steel assembly mainly depends on manual operation. The assembly efficiency is low, the precision is poor, the assembly depends on the skill of the assembler, and the product consistency is poor. It is urgent to develop automatic assembly equipment and apply high precision automatic assembly technology to solve this problem. In this paper, a precision automatic assembly equipment based on machine vision is developed for the assembly of magnetic steel components of a certain type of micro accelerometer. The equipment is divided into visual measurement module, assembly module, workbench module and assembly control module. The visual measurement module is used to obtain the position and attitude of the parts. The assembly module completes the tasks of picking up, moving and assembling the parts. The work table module provides the assembly space. The fixture realizes the functions of clamping and fixing after assembly. The assembly control module controls the orderly work of other modules of the equipment and provides the man-machine interface. According to the features of shell and magnetic steel parts, the operating device and fixture are designed to ensure the stability of assembly process, improve the assembly accuracy, and realize the real-time detection and control of assembly force. Visual measurement is a non-contact measurement method, which is fast and does not damage parts. In order to improve the accuracy and efficiency of visual measurement, an automatic focusing algorithm based on coarse and fine image gray value is developed. The variance function and the gradient variance function are used as the image definition evaluation functions in the two stages of rough refinement, and the mountain climbing method and the quadratic interpolation method are used to search the optimal solution. The illumination environment is set according to the characteristics of the magnetic steel and shell parts to ensure the image acquisition quality of the upper surface of the magnetic steel and shell parts. The median filter is used to preprocess the image with linear gray enhancement to improve the recognition accuracy. Based on the image stitching technology, the acquisition range of large magnification camera is expanded. Finally, the edge points are extracted and the circle is fitted with the least square method. The measuring task of the parts is completed, and the position information of the feature points of the parts to be assembled is obtained. The main factors affecting assembly accuracy are analyzed, and the error compensation model is established based on homogeneous coordinate transformation. The angle between image coordinate system, visual measurement coordinate system and assembly operation coordinate system is calibrated. The verticality error between the axes of the three-dimensional moving platform is compensated. The assembly accuracy can reach 10 渭 m, which meets the design requirements, assembly stability, consistency and so on.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TH824.4

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