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Evaluation of functional methods for human movement modelling

Gastaldi L., Lisco G., Pastarelli S.

Acta of Bioengineering and Biomechanics

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2015

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Vol. 17, no. 4

31--38

EN

Purpose: accurate assessment of human joint parameters is a critical issue for the quantitative movement analysis, due to a direct influence on motion patterns. In this study three different known functional methods are experimentally compared to identify knee joint kinematics for further gait and motion analysis purposes. Methods: taking into account the human knee physiology complexity, within its roto-translation, the study is conducted on a lower limb mechanical analogue with a polycentric hinge-based kinematic model. The device mimics a joint with a mobile axis of rotation whose position is definable. Sets of reflective markers are placed on the dummy and flexion-extension movements are imposed to the shank segment. Marker positions are acquired using an optoelectronic motion capture system (Vicon 512). Results: acquired markers’ positions are used as input data to the three functional methods considered. These ones approximate the polycentric knee joint with a fixed single axis model. Different ranges of motion and number of markers are considered for each functional method. Results are presented through the evaluation of accuracy and precision concerning both misalignment and distance errors between the estimated axis of rotation and the instantaneous polycentric one, used as reference. Conclusion: the study shows the feasibility of the identification of joint parameters with functional approaches applied on a polycentric mechanism, differently from those usually conceived by the reviewed algorithms. Moreover, it quantifies and compares the approximation errors using different algorithms, by varying number and position of markers, as well ranges of motion.

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Model based monitoring of hypothermic patients

Schwarz M., Heilmann C., Krueger M. W., Kiencke U.

Metrology and Measurement Systems

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2009

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Vol. 16, nr 3

443-455

EN

In open heart surgery the patient is connected to a heart-lung machine which pumps and oxygenizes the blood. The body core temperature is reduced by cooling the blood in a heat exchanger to reduce oxygen consumption of the tissues and so protect organs from hypoxia. Monitoring of vital parameters is crucial for safety of the patient. However, only little information is available from direct measurement. Models of haemodynamics and heat exchange in the human body are presented in this paper which provide the perfusionist with detailed data on blood flow and temperature in regions of the body which cannot be accessed by measurement devices. Simulation is performed on a real-time hardware platform which receives measured signals from the heart-lung machine via a serial interface.

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An Animated Auslan Tuition System

Yeates S., Holden E. J., Owens R.

Machine Graphics and Vision

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2003

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Vol. 12, No. 2

203-214

EN

An Animated Auslan Tuition System uses a computer general signer to provide flexible, visual Australian Sign Language (Auslan) educational tool. Signs are generated and animated by our generig Human Modelling System that is implemented in cross-platform object-oriented C++. The Human Modelling System consists of three modules: the core Human Modelling Module for model construction, manipulation and forward kinetics; the Model Rendering Module for displaying model configuration visually using OpenGL; and the Model Interpolation Module, for providing flexible partial-keyframe interpolation and animation control. These modules form the basis of the Auslan Tuition System, and allow the display of categorised sign phrases, interactive fingerspelling and contextual sign dialogue examples. The user has complete viewing control of sign display and animation, running on modest hardware.