Design optimisation of industrial robots using the Modelica multi-physics modeling language
Superior performance of industrial robots can only be achieved if the interaction of mechanics, electronics and software is taken into account already in the design phase. Conventional approaches to modelling, however, cannot cope with such multi-physics systems. The new Modelica modelling language has been specifically developed for this purpose. It also significantly increases re-usability of model components, since components adapt to the connection structure in which they are used. In the European resarch project “Real-time Simulation for Design of Multi-physics Systems“ (RealSim), efficient tools for modelling, simulating and optimising industrial robots are developed. A general Modelica MultiBody library (freely available from [1] or [2]) formed the basis for the development of a specific robot component library. A development environment for creating robot models out of the available components was provided, in which initial calculations to verify the first rough design can also be performed. Tools for automated optimisation were developed that take the initial design as the starting point. Afterwards, the performance of a design can than be verified in a real-time simulation before investing in building a real prototype. These powerful development tools provide the basis for an even more efficient development process and superior robot performance in the future.
Modelica Model for the youBot Manipulator
This paper presents the development of Modelica model for the youBot manipulator. Whereas other robotic simulations focus on the robot interaction with its environment, Modelica allows the modeling of the manipulator controllers and motors. The model was developed with a Modelica library for the manipulator’s components which provides modularity, reusability and abstraction. A comparison test with the actual system is performed to ensure the model accuracy. The test result shows promising result and provides possible future work. The Modelica model of the youBot manipulator is freely available.
High-frequency hearing thresholds: effects of age, occupational ultrasound and noise exposure
AbstractPurpose
It has been suggested that high-frequency audiometry (HFA) could represent a useful preventive measure in exposed workers. The aim was to investigate the effects of age, ultrasound and noise on high-frequency hearing thresholds.MethodsWe tested 24 industrial ultrasound-exposed subjects, 113 industrial noise-exposed subjects and 148 non-exposed subjects. Each subject was tested with both conventional-frequency (0.125–8 kHz) and high-frequency (9–18 kHz) audiometry.ResultsThe hearing threshold at high frequency deteriorated as a function of age, especially in subjects more than 30 years old. The ultrasound-exposed subjects had significantly higher hearing thresholds than the non-exposed ones at the high frequencies, being greatest from 10 to 14 kHz. This hearing loss was already significantly evident in subjects with exposure <5 years and increased with years of exposure and advancing age. The noise exposure group had significantly higher hearing thresholds than the non-exposed group at the conventional frequencies 4 and 6 kHz and at the high frequency of 14 kHz. After stratification for age, there was a significant difference between the two groups at 9–10 and 14–15 kHz only for those under 30 years of age.ConclusionMultivariate analysis indicated that age was the primary predictor, and noise and ultrasound exposure the secondary predictors of hearing thresholds in the high-frequency range. The results suggest that HFA could be useful in the early diagnosis of noise-induced hearing loss in younger groups of workers (under 30 years of age).
