The development of new robot structures, in particular of parallel kinematic machines(PKM), is widely systematized by different structure synthesis methods. Recent research increasingly focuses on PKM with less than six degrees of freedom(DOF). However, an overall comparison and evaluation of these structures is missing. In order to compare symmetrical PKM with three translational DOF, different evaluation criteria are used. Workspace, maximum actuation forces and velocities, power, actuator stiffness, accuracy and transmission behavior are taken into account to investigate strengths and weaknesses of the PKMs. A selection scheme based on possible configurations of translational PKM including different frame configurations is presented. Moreover, an optimization method based on a genetic algorithm is described to determine the geometric parameters of the selected PKM for an exemplary load case and a prescribed workspace. The values of the mentioned criteria are determined for all considered PKM with respect to certain boundary conditions. The distribution and spreading of these values within the prescribed workspace is presented by using box plots for each criterion. Thereby, the performance characteristics of the different structures can be compared directly. The results show that there is no "best" PKM. Further inquiries such as dynamic or stiffness analysis are necessary to extend the comparison and to finally select a PKM. . She received her diploma degree in mechanical engineering in 2010 from RWTH Aachen University, Germany. Her research interests include synthesis and analysis of parallel mechanism, mechanism theory, engineering design and development.
The ''Robots to Re-Construction'' Bots2ReC project was launched in 02/2016 to introduce mobile robotic units on construction sites for the automated removal of asbestos contamination. The novel use case of asbestos removal and the dedicated robotic system are introduced. After giving the motivation for the use case, a brief overview of recent approaches to mobile robotic systems on construction sites is given. Analysis of the use case and the situation of asbestos contamination in Europe follow. The project approach is shown, and specific challenges regarding mobility, perception, and collaboration are analyzed. The publication concludes with a brief description of the current prototype and an introduction of the project consortium. As we are addressing the first special edition of this journal, our focus is on the introduction of the use case, challenges, and approach rather than on specific scientific or technological solutions, that will follow during the course of the project. http://www. bots2rec.eu.
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