M. Milfelner, F. Cus
USE OF ERGOMEDICAL DATA FOR CONSTRUCTION

The present paper describes the technological system used to rationalize the production. An important feature in introducing this system into production is the correct arrangement and ergonomics of work station and components. The technological system for analyzing and introducing the ergonomic environment and products contains the ergonomic programme package ANTHROPOS and the digitalizing system GP12. As an example the analysis of the introduction of the work station in the working environment is presented.

E. Kaniusas, L. Mehnen, H. Pfützner, B. Saletuand R. Popovic
EVALUATION OF ACOUSTIC SIGNALS FOR THE DETECTION OF SLEEP APNEA EVENTS

The present paper concerns acoustic measurements in connection with the sleep apnea syndrome. The latter induces pathophysiologic changes in the respiratory and circulatory systems and is diagnosed by polysomnography (PSG). PSG comprises the measurement of many parameters and thus tends to be expensive and time consuming. In contrast to available portable devices which use many distributed sensors, we propose a single acoustic sensor in the heart region from which multiple information is derived through excessive signal processing. Measurement is performed by means of a microphone complemented by a stethoscope head. Analysis of the detected signal by means of histogram, cross correlation and FFT shows that it includes information an all three the cardiac activity, the respiratory activity and the snoring sounds. In order to obtain automatic monitoring of obstructive apnea events, a series of signal characteristics in both the time and the spectral domain (e.g., power density, histogram width, PCA components) are subject of processing through adaptive algorithms which are also used for classification. In addition, the method yields breathing patterns and diagnostically relevant physiological data such as changes of the heart rate and the rate of respiration. For the detection of central apnea event, the acoustic sensor is complemented by a magnetostrictive one.

T. Angeli
DYNAMOMETER FOR THE MEASUREMENT OF TORQUES ON HUMAN JOINTS

In the field of biomechanics, in sport as well as in rehabilitation, it is very important to deduce the muscle-force knowing the torque of the joints. So called knee-dynamometers are used for this purpose. These dynamometers must follow given velocity-courses of the measuring lever regardless of the torque to be measured. Up to now there are only dynamometers available for measuring static torques and torques with constant velocity. However, these dynamometers can only measure the torque of isometric contractions and extensions or flexions of the knee joint with constant angular velocity. Therefore the idea was born to design and construct a prototype which is able to measure the torque during acceleration-courses for different human joints. At the same time a new measuring method would ensure correct results by considering gravity or inertia of masses during acceleration. It became evident that the force-development of the physiologically contracted muscle differs to that of the electrically stimulated muscle.

A. Piratelli-Filho, B. Di Giacomo, M. L. Siqueira
DETERMINATION OF STRAIGHTNESS ERRORS IN A WELDING ROBOT

In some large industries, a robotic arm describing predefined paths in work volume and carrying a welding gun executes automatic welding operations. The deviations in relation to ideal robot arm predefined paths may cause severe distortions in welded parts. The displacement along a straight path must be close to the ideal straight line and the deviations cause a poor quality weld. In this case, the straightness errors in two orthogonal planes crossing the planned welding line can be considered as parameters to predict welding quality. In this work, an approach was used to investigate the performance of a welding cell that requires the determination of path straightness of a robot arm movement using online programming. This approach involves the use of a dial gauge connected to the robot arm and moved over a reference straight standard. The straightness was determined as the range of the measurement errors at each measuring line and was determined in several different locations in work volume. The results obtained showed that the different regions in work volume promote the change in weld quality and error compensation may be applied to improve the accuracy in welding operations.

V. Naydenov, P. Sente, C. Eugène
HOW TO USE REFLECTIVE OPTOCOUPLERS AS POSITION SENSORS

Due to its numerous qualities, namely their low cost, infrared reflective optocouplers are of large use in the industry to detect an object passing in their field of view. They nevertheless are mainly limited to deliver a pure dichotomic information. The purpose of the paper is to propose several solutions for using this component as an accurate position sensor at the industrial level. Linear and angular displacements are both considered with emphasis on a linear response. A global linearity of about 1% is achieved for a few centimeters and a few tens of degrees ranges.