Patrik Kutilek

Variability of centre of pressure movement during gait in young and middle-aged women

The variability of the centre of pressure (COP) movement is a tool that is often used for stability assessments during standing; however, this variable can provide relevant findings during dynamic conditions, which are more related to fall risks. The aim of this study was to investigate age-related differences in the variability of COP movement. Healthy young (younger group - 25 subjects, age 22.2 ± 1.8 years) and middle-aged (elder group - 25 subjects, age 56.6 ± 4.9 years) females participated in this study. The ground reaction forces and COP movement during walking at a self-selected speed were recorded using two force platforms. Each stance phase was divided into four subphases: loading response (LR), mid-stance (MSt), terminal stance (TSt) and preswing (PS). Standard deviations of the medial-lateral, anterior-posterior and total COP displacements were assessed. For statistical comparisons, one-way ANOVA and the Bonferroni post-hoc test were used. These results showed significantly higher COP movement variability in selected variables in the PS, LR and MSt subphases in the elder group (p < 0.05) compared with the younger group; no differences were found in the TSt subphase. A comparison of the subphases within the groups revealed significant differences (p < 0.001 for all cases and both groups) between the parameters in the LR × MSt, LR × TSt, MSt × PS and TSt×PS subphases. The LR and PS subphases showed significantly higher values for the variability parameters.

Methods of Measurement and Evaluation of Eye, Head and Shoulders Position in Neurological Practice

The position of the eye, head and shoulders can be negatively influenced by many diseases of the nervous system, (particularly by visual and vestibular disorders) (Cerny R. et al, 2006). Disturbances of the cervical vertebral column are another frequent cause of abnormal head position. In this chapter we describe advanced methods of measuring the precise position of the eye, head and shoulders in space. The systems and methods are designed for use in neurology to discover relationships between some neurological disorders (such as disorders of vestibular system) and postural head alignment. We have designed a system and a set of procedures for evaluating the inclination (roll), flexion (pitch) and rotation (yaw) of the head and the inclination (roll) and rotation (yaw) of the shoulders with resolution and accuracy from 1 to 2 (Hozman et al, 2007). We will also deal with systems designed for parallel measurement of eye and head positions and a new portable system for studying eye and head movements at the same time is described as well (Charfreitag et al, 2008). The main goal of this study is to describe new systems and possibilities of the present methods determined for diagnostics and therapy support in clinical neurology. Furthermore, we describe the benefits of each method for diagnosis in neurology.

Evaluation of relationship between the activity of upper limb and the piloting precision

Flying an aircraft requires a significant degree of coordination of upper and lower limbs. Such movements tend to be rather uncoordinated in the case of inexperienced pilots which results in inaccurate piloting. The aim of this study is to prove or disprove the dependence of the upper limb activity in relation to the aircraft steering during various actions which are required for precise maneuvering. We also deal with the design of a method to determine the degree of correlation between the movement of the hand and the airplane. The study was conducted on 8 subjects with the same level of experience during 11 hours of flight training on the simulator of type TRD40 and aircraft of type DA40. Subjects performed 14 maneuvers in total. Between takeoff and landing a recurring cycle of four maneuvers has been carried out by the subjects. Repeated maneuvers were in the order from the straight-and-level flight, horizontal turn by 360°, ascend turn by 180°, and descent turn by 180°. Recorded data except for basic flight data (magnetic course, banked and altitude) have been variables depicting the activity of the pilots upper limb. The activity was measured using triaxial accelerometer located on the dorsal side of the distal end of the forearm. The correlation coefficient proved relationship between the upper limb movement and aircraft steering both at bank and altitude. It testifies that change of bank and altitude of aircraft is directly connected with upper limb movements. Resultant activity standard deviation relation correlation coefficient is 0.7.

System for Precise Measurement of Head and Shoulders Position

The objective of our study is to develop a technique for precise head and shoulders posture measurement or, in other words, for measuring the native position of the head and shoulders in 3D space with accuracy to 1° in each direction. Until now, no cheap, widely applicable technique was presented.

FlexiGuard: Modular biotelemetry system for military applications

The article presents a FlexiGuard modular biotelemetric system for real-time monitoring of special military units. The main focus of the system is on automated monitoring of special forces via parallel monitoring of each member of the special team individually, witch includes collecting sets of physiologic (or environmental) parameters. The systems consists of a set of sensors (for monitoring temperature, heart rate, acceleration, humidity etc.) and modular sensing unit, which records the measured data and sends them to the visualization unit. The measured values (i.e. heart rate, surface temperature of the body and so on) are then visualized in the graphic user interface of the visualization unit. Testing of the functionality of the system took place in both laboratory and real environment. In the case of carrying out the measurements on 34 soldiers at series of 4 probands at the same time, the sensor networks worked without any loss of signal. During the data transfer to the visualization unit, a loss of approx 0.2% of packets occurred. The system thus can offer information to the commander, which may prove essential for the optimalization of operational strategies, taking the state of wellbeing of the team members into account.

Quantification of Trunk Postural Stability Using Convex Polyhedron of the Time-Series Accelerometer Data

Techniques to quantify postural stability usually rely on the evaluation of only two variables, that is, two coordinates of COP. However, by using three variables, that is, three components of acceleration vector, it is possible to describe human movement more precisely. For this purpose, a single three-axis accelerometer was used, making it possible to evaluate 3D movement by use of a novel method, convex polyhedron (CP), together with a traditional method, based on area of the confidence ellipse (ACE). Ten patients (Pts) with cerebellar ataxia and eleven healthy individuals of control group (CG) participated in the study. The results show a significant increase of volume of the CP (CPV) in Pts or CG standing on foam surface with eyes open (EO) and eyes closed (EC) after the EC phase. Significant difference between Pts and CG was found in all cases as well. Correlation coefficient indicates strong correlation between the CPV and ACE in most cases of patient examinations, thus confirming the possibility of quantification of postural instability by the introduced method of CPV.

Volume of confidence ellipsoid: a technique for quantifying trunk sway during stance

Abstract The position of the trunk can be negatively affected by many diseases. This work focuses on a noninvasive method of quantifying human postural stability and identifying defects in balance and coordination as a result of the nervous system pathology. We used a three-degree-of-freedom orientation tracker (Xsens MTx unit) placed on a patient’s trunk and measured three-dimensional (3-D) data (pitch, roll, and yaw) during quiet stance. The principal component analysis was used to analyze the data and to determine the volume of 3-D 95% confidence ellipsoid. Using this method, we were able to model the distribution of the measured 3-D data (pitch, roll, and yaw). Eight patients with degenerative cerebellar disease and eight healthy subjects in this study were measured during stance, with eyes open and eyes closed, and statistical analysis was performed. The results of the new method based on the 3-D confidence ellipsoid show that the volumes related to the patients are significantly larger than the volumes related to the healthy subjects. The concept of confidence ellipsoid volume, although known to the biomechanics community, has not been used before to study the postural balance problems. The method can also be used to study, for example, head and pelvis movements or alignments during stance.

Analysis and prediction of upper extremity movements by cyclograms

Quantification of upper extremity movement is a common objective in both research and clinical practice. Currently, methods based on angle-angle diagrams, also called cyclograms, seem to be promising. Nevertheless, compared to the study of lower limbs, the concept of angle-angle diagrams has not been systematically used to study upper limb movements during walking. The paper describes two examples of new methods based on angle-angle diagrams for application in rehabilitation and assistive robotics. The cyclograms represent information about the relationship between the angles and their changes over time. We used cyclograms as patterns for learning artificial neural networks and predicting the movement of upper-limb. Together with artificial intelligence, cyclograms offer wide scope of application in prosthesis control systems. Using bilateral cyclogram, the information about the relationship between the right and left arm joint angles is used to evaluate the symmetry of movements. The method based on the orientation of the bilateral cyclogram can be used as an additional method for determining the symmetry of movements of the upper limbs or exo-prosthesis.

THE EVALUATION OF THE PRACTICAL ADHESION STRENGTH OF BIOCOMPATIBLE THIN FILMS BY FUZZY LOGIC EXPERT SYSTEM AND INTERNATIONAL STANDARDS

Abstract This work focuses on describing an evaluation method used in nano- and micro-thin films based on fuzzy logic expert systems. The aim is the elimination of comparison complications with mechanical properties of tin films, practical adhesion being one of the most important characteristic of tin films. The basic method for evaluating the practical adhesion strength is scratch test method, while the issue is that research teams use measurement methods based on the non-uniform measurement conditions of adhesion of biocompatible thin films. The authors tested new evaluation method and procedure based on international standards and fuzzy rule based expert system in order to eliminate the problem of comparison of practical adhesion of the films. The article concentrates on testing and using the fuzzy logic expert system designed based on international standards for evaluating adhesion of thin films in nano and micro dimensions. The materials used for tests of the fuzzy expert system were DLC biocompatible layers and substrate a titanium alloy Ti6Al4V.

Motion Capture Camera System for Measurement of Head and Shoulders Position

The objective of our study was to develop a technique for precise head and shoulder posture measurement or, in other words, for measuring the native position of the head and shoulders in 3D space with accuracy to 1 ̊. No technique or cheap MoCap camera system has been previously developed that can be widely and easily used in clinical practice. New technique and MoCap system could have important applications, as there are many neurological disorders that affect the postural alignment position of the head and shoulders. In many cases, the abnormalities of the head position can be small and difficult to observe. Although an accurate method could contribute to the diagnosis of vestibular disorders and some other disorders, this issue was not systematically studied. MoCap system of head and shoulder posture measurement is based on combination of infrared camera image recognition and evaluation of data recorded by gyroscope. This method was chosen to offer precision less than 1 ̊ in each angle. The system consists of separate components – a headset equipped by gyro-accelerometer and infrared LEDs, infrared LEDs placed on patients shoulders, and a stand with two infrared cameras. The first camera is placed above the patient and the other in front of him. Our designed system provides direct information for physicians on the current position of the patients head and patients shoulders represented by the angles. Our method is cheaper and offers better application in the field of quantitative assessment of head and shoulder posture.