Pavel Smrcka

Fatigue Indicators of Drowsy Drivers Based on Analysis of Physiological Signals

The analysis of physiological signals (EEG, ECG EOG) of drowsy and alert drivers described here is aimed at determining the fatigue level of the driver while driving. We tested possible fatigue indicators: 1. extracted from EEG spectrum; 2. based on blinking frequency, interval histogram and speed of blinks; 3. fractal properties of RR interval-series. The first group of indicators is assumed to provide information about immediate fatigue level, whereas groups 2 and 3 are more suitable for determining the drivers global state (alert/drowsy).

New methods for precise detection of systolic complexes in the signal acquired from quantitative seismocardiograph

Quantitative seismocardiography is a simple and non-invasive method of measuring compression waves generated by heart activity. It provides important information about the cardiovascular system. The first important information acquired from quantitative seismocardiogram (QSCG) is the pseudo-period rate. This paper focuses just on the detection of pseudo-periods in the QSCG signal. Two methods of detection together with a method of sophisticated data preprocessing are presented. The results of the methods are demonstrated using real data.

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.

Wearable systems for monitoring the health condition of soldiers: Review and application

From the second half of the 1990s, thanks to more affordable and more powerful technology and systems for recording based on miniaturized sensors, we can observe a more intensive development of a system that monitors the physical and psychological conditions of soldiers. Systems for measuring of physical and medical data for the diagnostics of physical and psychological state has significantly spread. This study, however, examines the current technologies and usage of the wearable monitoring systems in military. The article can serve as a guide for choosing suitable and affordable systems of quantitative evaluation of physical and psychological conditions of soldiers. In addition, the innovative telemetry monitoring system (FlexiGuard system) composed of appropriate sensors is introduced. Based on previous researches and tests, FlexiGuard system and its sensors are recommended for use in military practice.

Evaluation of Bilateral Asymmetry of the Muscular Forces Using OpenSim Software and Bilateral Cyclograms

The aim of this article is to introduce a method of quantification of bilateral asymmetry of the muscular forces which can be used for rehabilitation, and also for evaluating the functionality and usability of the actuators of prosthesis. Our work focuses on quantification of asymmetry of the muscular forces using OpenSim software and bilateral cyclograms. A group of healthy children and children with cerebral palsy was measured using a Vicon MoCap system. The kinematic data were recorded and the OpenSim software system was used to identify the muscular forces, which are represented by time diagrams. The bilateral cyclograms were created to quantify the bilateral asymmetry of the muscular forces of the left and right sides of body. In order to quantify the asymmetry of the muscular forces, we have tested the application of method based on the shape of synchronized bilateral cyclograms.

The use of artificial neural networks to predict the muscle behavior

The aim of this article is to introduce methods of prediction of muscle behavior of the lower extremities based on artificial neural networks, which can be used for medical purposes. Our work focuses on predicting muscletendon forces and moments during human gait with the use of angle-time diagram. A group of healthy children and children with cerebral palsy were measured using a Vicon MoCap system. The kinematic data was recorded and the OpenSim software system was used to identify the joint angles, muscle-tendon forces and joint muscle moment, which are presented graphically with time diagrams. The musculus gastrocnemius medialis that is often studied in the context of cerebral palsy have been chosen to study the method of prediction. The diagrams of mean muscle-tendon force and mean moment are plotted and the data about the force-time and moment-time dependencies are used for training neural networks. The new way of prediction of muscle-tendon forces and moments based on neural networks was tested. Neural networks predicted the muscle forces and moments of healthy children and children with cerebral palsy. The designed method of prediction by neural networks could help to identify the difference between muscle behavior of healthy subjects and diseased subjects.

Compensation of the contrast and brightness attenuation with depth in confocal microscopy

A confocal laser scanning microscope (CLSM) captures images from a biological specimen in different depths and provides one with a stack of precisely registered fluorescent images. However, image intensities suffer from light loss distortions showing contrast and brightness degradation of images with depth. This effect causes problems in subsequent analysis and segmentation of biological objects. Therefore, we developed a post-processing method to correct this problem. It is a two step algorithm. In the first step the algorithm determines a standard histogram of the stack of images and in the second step histograms of individual images are warped according to this standard histogram. The algorithm results in more stable brightness and contrast of images through the stack.

Evaluation of the adhesion strength using digital microscope and international standards

The most frequently used method for scratch test in the international standards is progressive loading scratch test mode. Although the mentioned standards to measure practical adhesion of nano and micro thin films require optical microscope with magnifications between 100× and 500×, not only the optical microscopes, but even the international standards are not usually and largely used to study new biocompatible thin films. The authors designed a method and a custom-written program for the measurement and evaluation of scratches using digital microscope and digital microscope image analysis, which is based on the requirements of international standards for the determination of critical normal forces and capabilities of existing scratch testers. The proposed procedure and software were tested on the samples of TiN, Au, Pt and Pd biocompatible nano-thin layers. Delamination or loss of adhesion was observed in all cases, and two types of critical normal forces were determined. It was found that the calculated critical normal forces are largely similar in the three operations of the measurement of a sample. Thus, evaluation using critical scratch loads measured by three test operations seems to be sufficient. The new software and procedures allow us to evaluate the practical adhesions of a wide range of substrate and thin film materials, and gave us credible results.

A MYOELECTRIC PROSTHETIC ARM CONTROLLED BY A SENSOR-ACTUATOR LOOP

This paper describes new methods and systems designed for application in upper extremity prostheses. An artificial upper limb with this system is a robot arm controlled by EMG signals and a set of sensors. The new multi-sensor system is based on ultrasonic sensors, infrared sensors, Hall-effect sensors, a CO 2 sensor and a relative humidity sensor. The multi-sensor system is used to update a 3D map of objects in the robot’s environment, or it directly sends information about the environment to the control system of the myoelectric arm. Occupancy grid mapping is used to build a 3D map of the robot’s environment. The multi-sensor system can identify the distance of objects in 3D space, and the information from the system is used in a 3D map to identify potential collisions or a potentially dangerous environment, which could damage the prosthesis or the user. Information from the sensors and from the 3D map is evaluated using a fuzzy expert system. The control system of the myoelectric prosthetic arm can choose an adequate reaction on the basis of information from the fuzzy expert system. The systems and methods were designed and verified using MatLab/Simulink. They are aimed for use as assistive technology for disabled people.

Quantifying postural stability of patients with cerebellar disorder during quiet stance using three-axis accelerometer

Abstract This work focuses on the novelty of applying a 3-D postural analysis on the cerebellar disorders diagnosis and on introduction of an alternative to recent methods of quantifying the human postural stability during quiet stance, which uses a three-axis accelerometer. It introduces an advantage in the form of an ability to evaluate a complex three-dimensional (3-D) movement, as opposed to a major limitation of todaýs alternatives that evaluate only two coordinates in space. 3-D data (anterior-posterior, superior-inferior, and medio-lateral accelerations of a patients trunk) were obtained using a three-axis accelerometer (Xsens Mtx), enabling us to evaluate 3-D translational body movements on the basis of the average velocity (AV) of the point and the total length (TL) of the 3-dimensional trajectory. Then a pathological balance control has been identified from the 3-D plot of the three trajectories. The data were obtained from patients suffering from the progressive cerebellar ataxia as well as from healthy participants and were analyzed statistically. The analysis revealed several significant differences between the AVs and TLs of the patients versus the healthy participants.