HP99型堆垛机器人的运动分析及其模拟仿真

对ＨＰ９９型堆垛机器人进行了正运动学和逆运动学问题的分析,分别求出了正运动学解和逆运动学解。并在此基础上建立数学模型,应用Ｍａｔｌａｂ软件编程,进行运动学模拟仿真,验证了ＨＰ９９型堆垛机器人运动学正解、反解的准确性和运动的可行性,其仿真结构完全是真实可靠的,为以后的操作提供了数据和运动参考。     

大螺距圆弧螺纹的拟合法加工

介绍了大螺距圆弧螺纹拟合加工原理,建立了拟合加工中圆弧刀具中心的数学模型,提出了大螺距圆弧螺纹拟合加工宏程序的编制方法,对大螺距圆弧螺纹的高效加工具有指导意义。     

Formation of manufacturing cells based on material flows

The objective of many cell formation methods is to minimize overall material flows of parts. However, most methods do not incorporate several production factors that are extremely relevant to the material flows. We indicate and incorporate these factors into a nonlinear mathematical model and propose a heuristic methodology. Several problems are solved to illustrate the great benefits brought by these relevant production factors. We also test the computational performance of the proposed heuristic using three large-size problems. The computational results suggest that the approach produces reliable solutions in acceptable computational times.     

基于ADAMS的焊接机器人逆运动学求解

为了解决机器人运动学方程中的角度耦合问题,采用D－H方法建立了机器人的正运动学方程的数学模型,以PUMA560为研究对象求解,用ADAMS软件进行了仿真,其仿真结果与正运动学方程求解结果相近。验证了正运动学方程数学模型的正确性。在此基础上,采用解析法推导了焊接机器人逆运动学方程。此方法在整个推导过程中仅使用了逆矩阵相乘,解除了角度之间的耦合,推导出了各角的求解公式。此方法可为焊接机器人轨迹规划奠定基础。     

A study on the performance of some multi-response optimisation methods for WEDM processes

Wire electrical discharge machining (WEDM) processes are having several performance measures which are affected by different process parameters. In the recent past, researchers have attempted several systematic procedures for optimising the multiple responses of WEDM processes. However, most of these approaches use complex statistical/mathematical tools and are, therefore, impractical for application by the engineers who may not have a strong background in mathematics. Only a few methods, e.g., grey relational analysis and multiple response signal-to-noise ratio approaches use relatively simpler computational procedures. On the other hand, the computational procedures for the weighted signal-to-noise (WSN) ratio and VIKOR (VlseKriterijumska Optimizacija I Kompromisno Resenje in Serbian) methods are also quite simpler and, therefore, can easily be implemented by the engineers. However, an engineer needs to select the method that can give the best optimisation performance for the process. In this paper, the computational requirements for these four multi-response optimisation methods are standardised. Two sets of experimental data on WEDM processes are analysed using these standardised multi-response optimisation methods, and their relative performances are then compared. The results show that no method can lead to better optimisation than the WSN ratio method.     

Crawler robot kinematics modeling by using a two-wheeled approach

The aim of this paper is to analyze the kinematics of a small crawler robot. A mathematical model of kinematics based on a two-wheeled approach is proposed. This model is experimentally verified using vision-based motion measurements of a crawler vehicle equipped with encoders and a remote control system. It is assumed that the vehicle moves along a few curves with different angular speeds of its wheels. Based on the model of motion and the values of these speeds, numerical simulations are investigated. The results obtained from numerical and experimental validation are presented and discussed. The comparison delivered some important conclusions.

     

The mechanical efficiency and kinematics of pantograph-type manipulators

Pantograph mechanism has been well known for its motion feature of decoupled kinematics. Planar pantograph mechanism has been extensively used in machinery since the seventeenth century. Recently, three dimensional pantographs have been used in walking machine leg and manipulator designs. This is because, the pantograph mechanism possesses the following advantages decoupled kinematics, higher energy efficiency, good rigidity, less link inertia and compact drive systems. In this paper, the mechanical efficiency of the kinematics of pantograph type manipulators are studied. The mechanical efficiency of pantograph mechanisms and conventional open-chain and closed-chain type manipulators are studied and evaluated using the concept of modified geometric work. The kinematics of six-d.o.f., pantograph type manipulators are studied and special mechanisms which simplify the kinematics are introduced. The computational complexity of both Cartesian and cylindrical type pantograph manipulators are evaluated and compared with a PUMA type manipulator.     

PowerCube模块化机器人工作空间计算

以PowerCube模块化机器人为对象,采用D-H法建立机器人运动学数学模型.在比较现有的机器人工作空间求解方法的基础上,分别利用解析法和数值法绘制和计算出机器人的工作空间.将2个图形进行对比,结果表明2种方法所得的结果是一致的.     

六自由度并联运动机床奇异性研究

6-PSS并联运动机床的奇异性分析是6-PSS并联运动机床其它分析的基础,也是空间机构学分析的一个难点。本文首先解释了并联运动机床奇异性特征,通过建立6-PSS并联运动机床结构数学模型,实现了参数化设计。利用螺旋理论空间分析的优势,建立了6-PSS并联运动机床的Plücker坐标,方便地给出机床受力Jacobian矩阵,同时利用Matlab强大数学计算功能,精确的分析出并联机床的奇异性空间,降低了并联运动机床奇异分析的复杂性。     

Non-contact inspection of internal threads of machined parts

During the manufacturing process of mass-produced automotive parts, millions of internal threads are produced annually by each automaker. The manufacturers invest a lot of effort and resources to improve the quality of the threads by inspecting their features, mainly by using manual contact gages. The majority of manufactured threads are used in threaded joints that assemble two mechanical parts. However, there are threads that have additional functionality, for example, an automotive spark plug. Recently, automotive designers have found that the angular direction of the spark plug inside the combustion chamber affects the efficiency of the engine. Hence, the manufacturers are interested in measuring the exact position of the thread starting point, allowing them to position the plug in the right direction during the plug assembly process. Our technique allows precise measurement of the thread starting point and meets this requirement. In order to improve the quality of internal threads, it is essential to measure the threads dimensional features. It is also important to inspect its internal surface for defects such as the existence of burrs, thread discontinuities, or internal porosity defects. The paper introduces two novel non-contact electro-optical techniques for inspecting small-size internal threads. The first one enables in-process internal thread geometrical measurements using a high-precision laser sensor which utilizes a motorized periscope. The second technique is based on image processing and uses innovative machine vision; a line-scan technique which uses a CCD camera with a “sight pipe” panoramic optical device. The two methods are complementary; together they allow the practical inspection of all needed features of the internal thread. The methods were tested successfully.