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The implementation of a reliable vision system for a human-robot environment is a key issue for the collaborative production industry. The core challenge of human-robot collaboration is to ensure safety. Furthermore, a flexible safety system is required for frequently changing applications and work areas. This paper focuses on the development and application of a workspace monitoring system for safeguarding using radar sensors. The human-robot collaboration cell is designed to enable a flexible integration regardless of the work location. This results in higher productivity. Since no separating protective devices are provided for the cell, safety-oriented monitoring and control by suitable safety sensors is required. The methods to minimize the size of the necessary safety distance will be presented. The experimental validation shows that this safety system with radar sensors performs a reliable workspace monitoring system. The high robustness, reactivity and flexibility of the safet y concept makes this system usable for collaborative tasks in a real industrial environment.
Sensitive robots are an innovative technology of tomorrow ´s production. The Human–Robot-Collaboration (HRC) with its variable combination of unique skills represents a future-oriented form of work. Yet, there is a lack of experience in process realization, safety requirements are often not given and economic efficiency is still missing. There are a lot of innovative process solutions in research but industrial conditions are less considered. In this work, the approaches for the realization of standardizable HRCs for assembly operations in the automotive sector will be outlined. The aim is to present simple ways from the idea to series production by considering permitted limits. Based on an industrial application, innovative collaborations are realized with only few hardware and software components. In this context, standard compliant safety is ensured through internal system features and adjusted component designs. Additionally, an approach for HRC safety through real-time monitoring of the endeffector area is presented. As an
outlook there is a guideline for HRC realization.
The handling of flexible components, such as rubber sealings or cables, is an essential part of industrial manufacturing. Automating such processes through robotics is still a major challenge. Machine learning-based training of robots in combination with simulation has led to promising results in other areas of robotics. This approach can potentially be applied to assembly tasks as well. However, current simulation tools for robotics generally do not have capabilities for simulating flexible bodies. In this work, an approach for modeling such flexible bodies is proposed, which can be implemented with most common robotic simulation programs. Using the example of a rubber O-ring sealing, this approach was tested in such program and the results were compared with a professional multi-body physics engine. Realistic behavior of the O-ring was achieved with relatively low computation times.
Comparison of Commercial Physics-Based Simulation Environments with a Collision-Rich Benchmark
(2022)
For many years simulations are an important tool for researchers in many fields of application. With ongoing improvements in computing power and the rising requirements in the industry, simulation software has to shift the focus more towards industrial use cases. Especially in robotics and machine learning applications, the physical behavior has to be reproduced as realistic as possible to avoid unwanted collisions during runtime. In general, applications such as mounting or bin picking with an automated robot shall be evaluated. Therefore this paper investigates three in-use and one newly published software environment with included physics engine for realistic simulations that are commercially available. For comparison, a benchmark with collisions between two gears to imitate a mounting process is implemented and key features are defined. Only two of the simulation software manage to pass the benchmark. Despite that, both of them show restrictions revealing a lack of reliable software for realistic robot interaction simulation.
In laboratory practicals (labs), students actively investigate technical and scientific phenomena and thus experience autonomy, competence, and social embedding, factors that promote motivation. However, labs mostly rely on highly structured and instructive concepts and often require costly equipment. Therefore, the research question in this paper is: How can learner-centered teaching methods and learning formats be improved by rethinking the digitization of lab practicals?
The concept of the digital twin (DT), which accompanies a plant or machine throughout its entire life cycle, has further reinforced the role of Virtual Commissioning (VC). Of decisive importance for the economically and technically sensible use of the DT is its creation as early as possible in the life cycle. In the field of mechanical engineering, therefore, the first digital artifacts of the DT should ideally already be created in parallel with the mechanical design phase. The first step is the kinematization of the CAD model. This paper presents a new method for the semi-automated kinematization of 3D CAD models. The method uses a verbal description of the motion sequence desired by the designer, based on DIN EN 60848 (GRAFCET) [2] and using elements from VDI Guideline 2860 (handling functions) [8]. The presented method is easy to use and self-describing to a large extent. It enables designers to define in their own domain, in parallel to their mechanical designs, the desired motion sequence of the machine they have designed in machine-readable form. The actual kinematization of the CAD model is performed automatically. At the end, the kinematized design is available in COLLADA format and can be imported via the import interfaces of common simulation tools and can therefore be used for the DT.
Energy-saving potential for centrifugal pump storage operation using optimized control schemes
(2021)
AbstractIn this paper, we present the energy-saving potential of using optimized control for centrifugal pump–driven water storages. For this purpose, a Simulink pump-pipe-storage model is used. The equations and transfer function for steady-state and transient system behavior are presented and verified. Two different control strategies — optimum constant flow rate and level guided speed control — are compared to an allegedly optimal-driven pump with constant rotational speed. Twelve centrifugal pumps between 1 and 120 kW nominal power are evaluated to analyze the influence of different system parameters. The system characteristics, which are the static head, dynamic head factor, and maximum filling head, are varied 25 times for each pump in consideration of the pump’s best efficiency point. Thus, 300 different systems are optimized for each control strategy and compared to the constant speed control. The results are analyzed and the relevant system’s parameters, which have the most significant impact on energy savings, are shown. This theoretical energy–saving potential is verified with measurements, which show the high impact of the part load losses of the frequency converter and the electric motor. A law for identifying and estimation potential energy savings is developed using this information. Four use cases are analyzed with this law. It is shown that for a cost-minimal operation, not only the savings potential but also the operating time is decisive.
A shorter product life cycle and therefore, reduced
project duration is the major success factor for machinery and
plant engineering today. One use case for Virtual Commission-
ing (VC) is the early software test without an existing plant.
The primary effort of VC lies in the manual creation of the
plant model. There are various simulation tools with different
advantages available. Selecting one tool has consequences for
the whole engineering process. The exchange of models across
different tools is not possible or discouraged by the respective
vendors due to various reasons. This paper describes a concept to
exchange behavior models via the table-based import interfaces
for an automated model generation within common simulation
tools. The concept utilizes an approach to exchange the behavior
of components using the vendor-neutral and standardized pro-
gramming language PLCopenXML containing all IEC 61131-3
programming languages. This removes the main obstacle for a
broader industrial application of VC, as it minimizes the manual
effort for creating and exchanging behavior models through the
use of standardized library elements and existing interfaces.
The new seminar "Digital Twins for Virtual Commissioning of Production Machines" follows a technical approach that uses virtualization and offers the possibility to pursue an uncommon teaching method called problem-based learning (PBL). The seminar is divided into two parts, with fundamental theoretical knowledge in automation technology and systems modeling provided first. In the second part, the students use the dedicated software environment to edit projects on their own, and at this point the PBL approach is used. This method enables students to self-organize their learning process and take an active part in the seminar. The idea for the seminar and virtual teaching lab evolved from the industrial use case of testing software for programmable logic controllers (PLCs) without the real machine, using virtual commissioning (VC). The primary effort of VC lies in the manual creation of a digital representation of each mechatronic component providing the same behavior seen from PLC perspective. Students are taught to do this, create the so-called digital twin (DT).