Non-destructive evaluation of residual stress using the collaborative robot

在斯特拉斯克莱德大学的超声工程中心（CUE），焊接和丝+弧增材制造（WAAM）中残余应力的无损评估被认为是通过由Javadi博士领导的5年校长奖学金的更大计划的一部分。因此，将在该中心最先进的机器人设施内开发用于过程中残余应力测量的先进机器人系统：传感器自动化、机器人和控制中心（Sensor Enabled Automation，Robotics & Control Hub，简称EMT）。测量过程将使用（i）相控阵超声系统和（ii）灵活的机器人单元进行。机器人残余应力测量的创新思想有望通过减少人为误差和提高测量系统的定位精度来提高测量的可重复性和准确性，并节省测量时间。传统上，大多数残余应力测量方法都是手动进行的，具有一定的自动化程度，整个过程仍然需要高度熟练的操作员（NDE和残余应力领域的专家）进行监督。在该项目中，将使用与KUKA KMR iiwa类似的协作机器人（Cobot），与高技能操作员（该博士生）直接合作，促进从手动过程（残余应力测量）到自动化过程的过渡。这样的智能协作机器人可以在（A）对完工部件的离线测量和（B）高温过程中残余应力测量中帮助残余应力测量。对于离线测量，由于操作员应到达焊缝、热影响区（HAZ）和部件母材的不同部分进行全面的残余应力测量，因此预计将增加测量的灵活性。这种灵活性也需要处理部件的尺寸和几何形状的变化，因为WAAM部件的复杂几何形状在手动残余应力测量过程中很难完全覆盖。此外，该过程的某些部分在重复过程中是耗时的，操作员可以在其中一个测试部分上训练协作机器人，然后相同的过程将自动重复整个测量，从而获得更准确的结果并节省时间/能量。对于高温在线残余应力测量，协作机器人还可以对热样品进行初始测试和实验，以促进从手动测量到全自动在线检测的过渡。所有这些发展都将在本项目中考虑，以探索cobot残余应力测量系统的要求。

In the Centre for Ultrasonic Engineering (CUE) at the University of Strathclyde, the non-destructive evaluation of residual stress in welding and Wire + Arc Additive Manufacturing (WAAM) is considered as part of a larger programme through a 5-year Chancellor's fellowship led by Dr Javadi. Therefore, an advanced robotic system for the in-process residual stress measurement will be developed within the centre's state of the art robotic facility: Sensor Enabled Automation, Robotics & Control Hub (SEARCH). The measurement process will be carried out using (i) a phased array ultrasonic system and (ii) a flexible robotic cell. The innovative idea of robotic residual stress measurement is anticipated to increase the repeatability and the accuracy of the measurement, through reducing human errors and increasing the positioning accuracy of the measurement system, and also saving the measurement time. Traditionally, the majority of residual stress measurement methods are carried out manually with some basic automation, where the whole process still requires supervision by a highly skilled operator (expert in both areas of NDE and residual stress). In this project, a collaborative robot (Cobot) similar to KUKA KMR iiwa, will be used to facilitate the transition from a manual process (residual stress measurement) to an automated process in direct collaboration with the highly skilled operator (this PhD student). Such a smart collaborative robot can help with the residual stress measurement in both (A) offline measurement on the as-built components and (B) high-temperature in-process residual stress measurement. For the offline measurement, it is expected to increase the flexibility of the measurement as the operator should reach the different sections of weld, Heat Affected Zine (HAZ) and parent material of the component for the comprehensive residual stress measurement. This flexibility is also required to deal with the variations in the size and geometry of the components because the complex geometry of WAAM components is challenging to be fully covered during a manual residual stress measurement process. Furthermore, some parts of the process are time consuming in a repetitive procedure, The cobot can be trained by the operator on one of the testing sections and then the same process will be repeated automatically for the whole measurement reaching a more accurate results and saving time/energy. For the high-temperature in-process residual stress measurement, the cobot can also allow the initial testing and experiments on the hot sample to facilitate the transition from the manual measurement to the fully automated in-process inspection. All of these developments will be considered in this project to explore the requirements of a system of cobot residual stress measurement.