Determination of the rotational vibration behaviour of hand-arm systems in the context of user-centered product development

• Applicant: Professor Dr.-Ing. Sven Matthiesen
• Subject Area: Engineering Design, Machine Elements, Product Development
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 408254169

Power tools (handheld devices) and many other technical systems are in direct dynamic interaction with the user. In the development of such systems, it is essential to take these interactions into account, as they affect all system components. A significant part of these interactions consists of passive interactions, i. e. those that originate from the dynamics and are only influenced by the user indirectly. In the simulation-supported development of technical systems, these passive interactions can be implemented using vibration models. These models are based on the mechanical impedance of the user, which can be understood as mechanical resistance to vibration excitation. The impedance is subject to many influencing factors such as arm position, gripping force and contact pressure. The influencing factors for translational excitation directions have been the focus of research for a long time. However, many systems have a main vibration excitation in rotational directions (e. g. cordless screwdrivers or angle grinders). The aim of the proposal is to close this knowledge gap by researching the mechanical impedance of the user in the three rotational space directions. In application studies, the variation of the influencing factors on impedance is first determined in real application scenarios. Exemplary power tools modified for measurement are used. Subsequently, the user's impedances are investigated at the DFG-funded user interaction test bench (UIT) of the IPEK. The UIT is a two-shaker system for the superimposed translational and rotational vibration excitation of the human hand-arm system using an attached measuring handle. For this purpose, the user interaction test bench is equipped with exemplary handle contours in order to generate relevant results.As a result, impedance diagrams of the user's rotational impedance are generated, from which fundamental hand-arm models for simulation-supported product development can be derived in further research.

• DFG Programme: Research Grants