Robot trajectory planning using OLP and structured light 3D machine vision

This paper proposes a new methodology for robotic offline programming (OLP) addressing the issue of automatic program generation directly from 3D CAD models and verification through online 3D reconstruction. Limitations of current OLP include manufacturing tolerances between CAD and workpieces and inaccuracies in workpiece placement and modelled work cell. These issues are addressed and demonstrated through surface scanning, registration, and global and local error estimation. The method allows the robot to adjust the welding path designed from the CAD model to the actual workpiece. Alternatively, for non-repetitive tasks and where a CAD model is not available, it is possible to interactively define the path online over the scanned surface

Generation of rule-adhering robot programs for aluminium welding automatically from CAD

This paper presents a method to automatically generate robot welding programs from CAD to address the ever-constant demand for product customisation. Furthermore, to ensure that proper welding operations and structural integrity are met, the generated programs also consider the welding conditions and requirements. These welding conditions and requirements are defined by the weld direction and face relative to gravity and surrounding geometry, which has not been observed in the present research sphere. To achieve this, the approach leverages information that can be extracted from a topological analysis of tessellated geometry local to the weld joint in conjunction with available CAD API functions. Finally, an implementation of the method using Siemens NX and the Robotics Toolbox for Python is presented and tested on three geometrically different node configurations and a stiffener piece provided by industrial collaborators. In all, the proposed system was able to correctly generate programs adhering to allowed welding operations as long as a solution existed. For the more complex node configurations (which require reorientation when welded by humans), 32 weld path programs out of 42 were generated based on the given criteria. For the least complex node, a total of 20 out of 24 were generated with the same criteria. All 14 weld programs were generated for the stiffener representation.publishedVersio

On Sensor-Controlled Robotized One-off Manufacturing

A semi-automatic task oriented system structure has been developed and tested on an arc welding application. In normal industrial robot programming, the path is created and the process is based upon the decided path. Here a process-oriented method is proposed instead. It is natural to focus on the process, since the path is in reality a result of process needs. Another benefit of choosing process focus, is that it automatically leads us into task oriented thoughts, which in turn can be split in sub-tasks, one for each part of the process with similar process-characteristics. By carefully choosing and encapsulating the information needed to execute a sub-task, this component can be re-used whenever the actual subtask occurs. By using virtual sensors and generic interfaces to robots and sensors, applications built upon the system design do not change between simulation and actual shop floor runs. The system allows a mix of real- and simulated components during simulation and run-time