沈斌分享 http://blog.sciencenet.cn/u/bshen 同济大学中德学院机械工程系主任、制造执行系统(MES)分会理事长

博文

提高工业机器人机械加工精度的方法研究

已有 1492 次阅读 2019-8-27 09:48 |个人分类:硕士研究生毕业论文|系统分类:论文交流|关键词:学者| 工业机器人, 加工精度, 轨迹补偿, 多体仿真模型, 三维扫描 |文章来源:转载

 

硕士学位毕业论文

硕士研究生:巩照卿

指导教师:沈斌 教授 

答辩时间:2015.03


摘 要

如今,工业机器人已成为不可缺少的重要的自动化装备,大量装备于汽车行业、电子电气行业等。随着工业机器人速度与精度的不断提升,其在机械加工行业表现出越来越高的应用价值。相比传统的机床,工业机器人具有灵活、高效的优势。此外,工业机器人的购买与维护成本较低,具有突出的性价比。

但是,工业机器人自身的刚度较低,加工中在过程力的作用下,刀具轨迹的偏移比较严重,从而导致加工误差较大。因此,本文主要从刀具轨迹补偿的角度出发,对几种轨迹补偿的方法进行了研究。本论文主要研究工作及成果如下:

1. 全面分析了影响机器人加工精度的各种因素,包括机器人的机械结构、驱动系统、工件、编程、加工过程、刀具等几个方面。其中,由机器人的制造及装配引起的几何误差占主要部分,对于非几何因素则主要是由机器人关节的柔性导致。

2. 研究了机器人运动学,利用修正的D-H理论建立机器人的正运动学模型。在Matlab/Simulink中,借助SimMechanics建立了机器人的多体仿真模型。通过该模型,结合参数辨识得到的关节刚度参数,可以准确地预测刀具中心点(TCP)在过程力的影响下的实际位置。

3. 研究了基于三维扫描技术的补偿方法。该方法结合了反向工程与三维图像处理等技术。研究了迭代就近点算法,该方法用于将两个三维模型进行配准的。阐述了基于Dexel模型的三维表示法。该表示法将三维实体表示成一系列一维的柱体,极大地减少了数据量,实现了三维模型之间高效的布尔运算。

4. 研究了基于光学传感器的补偿方法。研究了光学坐标测量系统的工作原理。该方法是通过光学坐标测量系统对刀具的实际轨迹进行动态测量,从而确定刀具轨迹的偏差。

 

关键词:工业机器人;加工精度;轨迹补偿;多体仿真模型;三维扫描;光学坐标测量仪

 

Abstract

Industrial robots have become an indispensable automation equipment, which are mostly installed in automotive, electrical and electronics industries. With the continuously improvement of the speed and accuracy, industrial robots have shown an increasing application value in the machining industry. Compared with conventional machine tool, industrial robots are flexible and efficient. In addition, the purchase and maintenance costs of industrial robots are much lower, which makes industrial robots with outstanding cost performance.

However, the industrial robots have smaller structural stiffness, which leads to large processing error under the influence of the process force. The main contents are summarized as follows:

1. Analysis of various factors that influence the machining accuracy of the industrial robots, including several aspects such as robot mechanical structure, drivetrain, workpiece, programming, processing, and cutting tools. Among them, the geometric error caused by manufacturing and assembly play an important role. For the non-geometric error, the main cause are flexibility of the robot joints.

2. Based on robotics the forward kinematics model of the robot are built using the modified D-H convention. In Matlab/Simulink, the Multi-body simulation Model of the robot was established. Combining the joint stiffness parameters this model can accurately predict the actual position of TCP under the influence of the process force.

3. Camera-based compensation method was researched. This method combines the technology of the reverse engineering and the 3D-image processing. Through ICP algorithm two 3D models can be aligned. With the use of dexel-based description a 3D body will be expressed as a series of 1D columns, which achieve an efficient Boolean operation between two three-dimensional model.

4. Optical sensors-based compensation method was researched. The working principle of optical coordinate measuring system was beschre. With the use of this system the actual toolpath will be measured and then the deviation of toolpath can be determined.   

 

Keywords: industrial robot, machining accuracy, trajectory compensation, multi-body-model, 3D-Scanner, 3D coordinate measuring system




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