We propose a novel simple method for quantitative and qualitative finger-tapping assessment based on miniature inertial sensors (3D gyroscopes) placed on the thumb and index-finger. We propose a ...simplified description of the finger tapping by using a single angle, describing rotation around a dominant axis. The method was verified on twelve subjects, who performed various tapping tasks, mimicking impaired patterns. The obtained tapping angles were compared with results of a motion capture camera system, demonstrating excellent accuracy. The root-mean-square (RMS) error between the two sets of data is, on average, below 4°, and the intraclass correlation coefficient is, on average, greater than 0.972. Data obtained by the proposed method may be used together with scores from clinical tests to enable a better diagnostic. Along with hardware simplicity, this makes the proposed method a promising candidate for use in clinical practice. Furthermore, our definition of the tapping angle can be applied to all tapping assessment systems.
A new method for estimation of angles of leg segments and joints, which uses accelerometer arrays attached to body segments, is described. An array consists of two accelerometers mounted on a rigid ...rod. The absolute angle of each body segment was determined by band pass filtering of the differences between signals from parallel axes from two accelerometers mounted on the same rod. Joint angles were evaluated by subtracting absolute angles of the neighboring segments. This method eliminates the need for double integration as well as the drift typical for double integration. The efficiency of the algorithm is illustrated by experimental results involving healthy subjects who walked on a treadmill at various speeds, ranging between 0.15 m/s and 2.0 m/s. The validation was performed by comparing the estimated joint angles with the joint angles measured with flexible goniometers. The discrepancies were assessed by the differences between the two sets of data (obtained to be below 6 degrees) and by the Pearson correlation coefficient (greater than 0.97 for the knee angle and greater than 0.85 for the ankle angle).
Abstract A new data processing method is described for estimation of angles of leg segments, joint angles, and trajectories in the sagittal plane from data recorded by sensors units mounted at the ...lateral side of leg segments. Each sensor unit comprises a pair of three-dimensional accelerometers which send data wirelessly to a PC. The accelerometer signals comprise time-varying and temperature-dependent offset, which leads to drift and diverged signals after integration. The key features of the proposed method are to model the offset by a slowly varying function of time (a cubic spline polynomial) and evaluate the polynomial coefficients by nonlinear numerical simplex optimization with the goal to reduce the drift in processed signals (angles and movement displacements). The angles and trajectories estimated by our method were compared with angles measured by an optical motion capture system. The comparison shows that the errors for angles (rms) were below 4° and the errors in stride length were below 2%. The algorithm developed is applicable for real-time and off-line analysis of gait. The method does not need any adaptation with respect to gait velocity or individuality of gait.
The control of movement in humans is hierarchical and distributed and uses feedback. An assistive system could be best integrated into the therapy of a human with a central nervous system lesion if ...the system is controlled in a similar manner. Here, we present a novel wireless architecture and routing protocol for a distributed functional electrical stimulation system that enables control of movement.
The new system comprises a set of miniature battery-powered devices with stimulating and sensing functionality mounted on the body of the subject. The devices communicate wirelessly with one coordinator device, which is connected to a host computer. The control algorithm runs on the computer in open- or closed-loop form. A prototype of the system was designed using commercial, off-the-shelf components. The propagation characteristics of electromagnetic waves and the distributed nature of the system were considered during the development of a two-hop routing protocol, which was implemented in the prototype's software.
The outcomes of this research include a novel system architecture and routing protocol and a functional prototype based on commercial, off-the-shelf components. A proof-of-concept study was performed on a hemiplegic subject with paresis of the right arm. The subject was tasked with generating a fully functional palmar grasp (closing of the fingers). One node was used to provide this movement, while a second node controlled the activation of extensor muscles to eliminate undesired wrist flexion. The system was tested with the open- and closed-loop control algorithms.
The system fulfilled technical and application requirements. The novel communication protocol enabled reliable real-time use of the system in both closed- and open-loop forms. The testing on a patient showed that the multi-node system could operate effectively to generate functional movement.
Alternation of walking pattern decreases quality of life and may result in falls and injuries. Freezing of gait (FOG) in Parkinson's disease (PD) patients occurs occasionally and intermittently, ...appearing in a random, inexplicable manner. In order to detect typical disturbances during walking, we designed an expert system for automatic classification of various gait patterns. The proposed method is based on processing of data obtained from an inertial sensor mounted on shank. The algorithm separates normal from abnormal gait using Pearson's correlation and describes each stride by duration, shank displacement, and spectral components. A rule-based data processing classifies strides as normal, short (short + ) or very short (short - ) strides, FOG with tremor (FOG + ) or FOG with complete motor block (FOG - ). The algorithm also distinguishes between straight and turning strides. In 12 PD patients, FOG + and FOG - were identified correctly in 100% of strides, while normal strides were recognized in 95% of cases. Short + and short - strides were identified in about 84% and 78%. Turning strides were correctly identified in 88% of cases. The proposed method may be used as an expert system for detailed stride classification, providing warning for severe FOG episodes and near-fall situations.
This paper deals with the central powering of very low power sensor networks deployed over wide areas. Although wireless communications are nowadays dominant in the majority of implementations, wired ...differential communications sometimes provide the only ultimately reliable solution. In a large-scale network, it is of interest to implement both communication and powering with a small number of thin conductors. The consequential problem of the serial resistance of the long powering lines appears as the limiting factor. Sensor nodes powered with linear supply support very low power consumption, but the current flow through ground loops creates common mode voltage on communication lines. An introduction of the galvanic isolation resolves the common mode issue, but the isolation usually consumes more power than a sensor node itself, which in total gives even worse results than linear regulation. Moreover, a galvanic isolation demands an additional reference conductor for signal return path. In this paper, a novel approach to the realization of a floating linear power supply is proposed, incorporating advantages of both linear and isolated solutions. The new power supply scheme retains linear regulation characteristics regarding low power consumption, at the same time eliminating common mode voltage issue, such as an isolated power supply.
Postural impairments and gait disorders in Parkinson's disease (PD) affect limits of stability, impaire postural adjustment, and evoke poor responses to perturbation. In the later stage of the ...disease, some patients can suffer from episodic features such as freezing of gait (FOG). Objective gait assessment and monitoring progress of the disease can give clinicians and therapist important information about changes in gait pattern and potential gait deviations, in order to prevent concomitant falls. The aim of this study was to propose a method for identification of freezing episodes and gait disturbances in patients with PD. A wireless inertial sensor system can be used to provide follow-up of the treatment effects or progress of the disease.
The system is simple for mounting a subject, comfortable, simple for installing and recording, reliable and provides high-quality sensor data. A total of 12 patients were recorded and tested. Software calculates various gait parameters that could be estimated. User friendly visual tool provides information about changes in gait characteristics, either in a form of spectrogram or by observing spatiotemporal parameters. Based on these parameters, the algorithm performs classification of strides and identification of FOG types.
The described stride classification was merged with an algorithm for stride reconstruction resulting in a useful graphical tool that allows clinicians to inspect and analyze subject's movements.
The described gait assessment system can be used for detection and categorization of gait disturbances by applying rule-based classification based on stride length, stride time, and frequency of the shank segment movements. The method provides an valuable graphical interface which is easy to interpret and provides clinicians and therapists with valuable information regarding the temporal changes in gait.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
We describe design and verification of a novel autonomous sensor system (Magnetic Cubes) for evaluating the distance between two points as well as the rotation matrix between the coordinate systems ...attached to the sensors. The system is based on two sensors, each comprising three orthogonal coils wound on foam cubes, and near-field coupling between the sensors, which operate the medium frequency band. Testing and verification of the designed system was done by performing various 2D and 3D movements, and comparing positions and orientations estimated by Magnetic Cubes with those measured by an optical motion capture system. In all cases, good agreement is obtained: the RMS error for the estimation of the distances between the cubes is less than 10 mm (less than 2%), while the RMS errors for the estimation of the Cartesian coordinates are less than 7%. The discrepancies between the results obtained from the two systems were also assessed by the Pearson correlation coefficient (greater than 0.9 for the Cartesian coordinates and greater than 0.99 for the distances between the cubes).
This paper presents a fast and accurate method for programming simple strategies for small autonomous robots based on embedded processing platforms. There are several approaches in programming of ...mobile and industrial robots, but the most common one is online programming. This method begins with so called teaching phase during which human operator guides the robot by issuing a set of simple commands. All that commands are automatically logged and saved into a command log, which in the operation phase eventually serves as final program. In case of industrial robots, the whole process including teaching and operation phase runs on the same platform, usually PC, which by the rule has convenient user interface. On the other side, small embedded robot platforms do not have appropriate user interfaces and their programs must be written in the form of hard-coded precompiled firmware. This paper describes the architecture of the robot and supporting system which are designed in the way that support convenient usage of PC based software during development phase, and a fast and accurate method for translation of tested command sequence into the embedded platform firmware running the robot during the deployment phase.
Funkcionalna električna stimulacija se koristi za vraćanje funkcije nervnomišićnom sistemu čoveka oštećenom fizičkom povredom, bolešću ili nekim drugim uzrokom. Kontrolisanim strujnim ili naponskim ...impulsima se vrši pobunjivanje nervnih motornih ili senzornih vlakana što se odražava kroz aktivaciju mišića. Posledica toga je restauracija funkcionalnog kretanja pojedinačnih ili grupe mišića.Počeci primene funkcionalne električne stimulacije sežu u šezdesete godine dvadesetog veka, kada je projektovan i proizveden prvi upotrebljiv električni stimulator, namenjen korekciji poremećaja padajućeg stopala. Nada da će tehnologija ubrzo omogućiti paralizovanim osobama da se ponovo pokreću podstakla je u narednim godinama razvoj mnogih rešenja za sisteme električne stimulacije. Meñutim, današnje stanje, pola veka kasnije, pokazuje da i pored jasne motivacije i ogromnog napretka na polju tehnologije još uvek nema značajnog pomaka na tom putu.Konzervativne strategije upravljanja električnom stimulacijom se zasnivaju na centralizovanom upravljanju. Raspoloživi istraživački sistemi se odlikuju manjim ili većim brojem senzorskih ulaza i nezavisnih stimulacionih kanala. Generalne mane su mnoštvo provodnika, komplikovane procedure postavljanja i podešavanja i vezanost za laboratoriju. Komercijalni sistemi su jednostavni za korišćenje ali imaju slabe funkcionalne performanse.U ovoj disertaciji je predstavljena nova arhitektura distribuiranog sistema za električnu stimulaciju inspirisana prirodnim biološkim sistemom. Nova filozofija u razumevanju mehanizma kretanja počiva na ideji hijerarhijski kontrolisane distribuiranosti u nervnom sistemu. Nekoliko kontrolnih sprega na različitim nivoima nervnog sistema doprinose ovoj kontroli: silazna motorna kontrola iz motornog korteksa (u mozgu), mreža generatora ritma u kičmenoj moždini (spinalni steppinggenerator) i senzorna povratna sprega za kontrolu hoda (sa zglobova u pokretu, mišića i kože).
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