Manufacturing knowledge for industrial robot systems: Review and synthesis of model architecture

Alexander Kuss, Julian R. Diaz P., Rebecca Hollmann, Thomas Dietz, Martin Hägele

This paper reviews the state of the art of models in robotic manufacturing applications. Moreover, a model architecture is proposed that is adequate for capturing knowledge of manufacturing processes in small and medium sized enterprises. The proposed architecture improves existing approaches by introducing a technology model that allows modeling of specific knowledge of manufacturing processes. This enables automatic generation of robot programs and supports reusability of manufacturing knowledge in industrial production scenarios. The usage of the presented model architecture is shown for a robotic welding application.

Nordic test and demonstration facilities: A mapping of test and demonstration facilities in the Nordic region

Leif Henrik Jakobsen, Benita Kidmose Rytz, Stig Yding Sørensen, Göran Hallin

In the Nordic countries, manufacturing plays a vital socio-economic role by contributing to employment and the economy at large. The key prerequisites are a high productivity and a strong competitive edge. One of the ways to obtain and maintain a competitive edge is if (small and medium-sized) companies apply new knowledge and new technologies. To support the use of new technologies by companies, easy access to testing of new products and technologies is a decisive factor for the companies to gain knowledge of and inspiration for the use of the new technologies in their current business. This report presents a mapping of test and demonstration facilities in the Nordic countries, including ten good practice examples of such facilities as well as political initiatives in the Nordic countries, including specific strategies for setting up and structuring test and demonstration facilities.

Automatic Close-optimal Workpiece Positioning for Robotic Manufacturing.

Julian R.Diaz P., Poulastya Mukherjee, Alexander Verl

Robot programming is still an expert dependent and not automatically optimized task. In order to make this process more automatic and intuitive for the end-user, this paper presents a novel approach to determine a close-optimal workpiece pose for different robotic manufacturing processes like welding and milling. The approach is based on a model-based interpretation of the Product, Process, and Resource (PPR) components defined in an internally developed Computer-Aided Manufacturing (CAM) software. After the interpretation addressed to simplify the path planning, an algorithm uses sample-based motion planning techniques and optimization algorithms, in order to find optimal motions in reaction to infeasible states of the robot (i.e. maximum joint limits and reachability) and a close-optimal workpiece pose. The optimized path planning is achieved by exploring an interpreted Configuration Space (C-space) using a Degree of Freedom (DoF) of the Robot Manufacturing Processes (RMP) and by interpreting its constraints. Simulation results are presented for robotic welding and milling task by optimizing welding orientations and robot stiffness respectively in the path planning and the joint movements and gravity cost criteria in the workpiece positioning. Optimization of these criteria could be used in RMP to address improvement of the process quality.

Automatic Motion Generation for Robotic Milling Optimizing Stiffness with Sample-Based Planning

Julian R.Diaz P., Ulrich Schneider, Arjun Sridhar, Alexander Verl

Optimal and intuitive robotic machining is still a challenge. One of the main reasons for this is the lack of robot stiffness, which is also dependent on the robot positioning in the Cartesian space. To make up for this deficiency and with the aim of increasing robot machining accuracy, this contribution describes a solution approach for optimizing the stiffness over a desired milling path using the free degree of freedom of the machining process. The optimal motion is computed based on the semantic and mathematical interpretation of the manufacturing process modeled on its components: product, process and resource; and by configuring automatically a sample-based motion problem and the transition-based rapid-random tree algorithm for computing an optimal motion. The approach is simulated on a CAM software for a machining path revealing its functionality and outlining future potentials for the optimal motion generation for robotic machining processes. View Full-Text

Deformable shape registration using surface-based free-form deformations in robotic welding

Alexander Kuss, Konstantin Ksensow, Alexander Verl

In this paper, a novel approach is presented to perform a deformable shape registration of workpiece geometries in robotic welding. Based on the free-form deformation (FFD) method, a surface-based extension FFDS is presented where the initial shape of the control points lattice corresponds to the shape of the surface to be deformed. A point-based registration is performed using the sum of least squares criteria to obtain the non-rigid shape transformation. The deformation is applied to the computer-aided design (CAD) model of the workpiece geometry preserving its topology for subsequent robot path planning to move a welding gun along the deformed part contours. The performance of the presented approach is evaluated using virtual test data and rea measurements of a welding workpiece obtained with a 3D sensor. Moreover, the performance of this approach is compared to state of the art deformable shape registration revealing a significant reduction of computation time and the usability for path planning in robotic welding.

High accurate robotic drilling with external sensor and compliance model-based compensation

Posada Diaz, Ricardo Julian, Ulrich Schneider, Sergej Pidan, Milad Geravand, Patrick Stelzer, Alexander Verl

High accurate absolute robot positioning is a requirement, and still a challenge, in many applications, such as drilling in the aerospace industry. The accuracy is affected due to many sources of errors from robot model, tool calibration, sensor and product uncertainties. While model-based error compensation cannot reach the desired accuracy, sensor-based compensation appears as the practical solution to increase the robot positioning accuracy. A structured analysis of the error sources in robotic manufacturing processes can facilitate error identification and further compensation. This paper describes an error source breaking down approach for analyzing robotic manufacturing processes. Moreover, an external sensor-based compensation is proposed for error reduction and error identification. Comparison with a compliance model-based compensation is performed. The proposed approach is applied to a robotic drilling process for aircraft manufacturing, considered a general and real industrial application. Further validation through experimentation is performed. The validation revealed a clear improvement in robot positioning accuracy and the benefits of the proposed error source structure for analysis.

Automatic optimal motion generation for robotic manufacturing processes: Optimal collision avoidance in robotic welding

Posada Diaz, Ricardo Julian, Thomas Dietz, Philip Ockert, Alexander Kuss, Martin Hägele, Alexander Verl

Optimal, efficient and intuitive robotic programming is still a challenge in robotic manufacturing and one of the main reasons why robots are not widely implemented in small and medium-sized enterprises (SME). In order to effectively and efficiently respond to the current product variability requirements, SMEs require easy and optimal programmable robotic manufacturing systems in order to achieve profitable and rapid changeover. To make up for this deficiency, this paper proposes a solution approach for computing optimal motions for manufacturing processes based on the interpretation of the manufacturing process and an automatic configuration of a state of the art sample-based algorithm, the Rapidly-exploring Random Tree RRT* which is provably asymptotically optimal, using as inputs the semantic and mathematical descriptions of the product, process and resource components. The approach is simulated on the example of collision avoidance for different scenarios in robotic welding revealing its functionality and outlining future potentials for the optimal motion generation for robotic manufacturing processes.

A survey about development interests in industrial robotics

Christoph Hellmann, Thilo Zimmermann, Werner Kraus

In this contribution the first results of a European wide survey on companies development interests in the area of industrial robotics are presented. The survey was conducted during training courses organised by the Robott-Net consortium for robot enthusiast in four different locations in Europe. 139 specialist from 73 industrial companies with an interest in robotics participated in this survey. The results show that companies are researching and looking for robotic automation solutions which are easy to use and reconfigurable. The biggest barrier for automation using robotics perceived by the participants is the lack of available technology. Another outcome of the survey is a ranking of the processes which companies want to automate using robotics.