Search PubMed⌕ Search

Biomedical subjects

T Bajd

Publications and source records attributed to T Bajd.

51 records · Page 3Linked to original sources
PubMed1977

Standardization of kinematic gait measurements and automatic pathological gait pattern diagnostics.

The estimation of patients gait in the field of rehabilitation is the starting point for an appropirate therapy decision and convenient prosthesis or orthosis choice. The measurement and estimation of human locomotion is increasingly being transferred to every day clinical use. In recent times many systems are intended for kinematic gait parameters measurements: stroboscopic photography, movie camera, TV picture analysis, TV signal analysis, chronocyclographical measurement, polarised light goniometer, the "Selspot" system, parallelgram goniometers, exoskeleton goniometers. In the paper the role of the computer in gait measurements is also determined. The problems of the choice of parameters to be measured, unique reference coordinate systems and normal gait pattern are encountered in this work. Finally two versions of pathological gait pattern estimation are described: clinical gait analysis and mathematical quantitative gait analysis. A combination of both methods provides an efficient, compact automatic pathological gait pattern diagnostics.

Automation↗
PubMedDate not supplied

Use of telekinesthetic feedback in walking assisted by functional electrical stimulation.

A telekinesthetic feedback implemented into functional electrical stimulation (FES) orthosis is described. Single channel FES is used to provoke ankle dorsiflexion during walking. FES is controlled manually by a special lever, built into the handle of the crutch. The angular position of the lever defines the intensity of stimulation and thus the magnitude of the ankle dorsiflexion. The measured joint angle provides the feedback information about the ankle joint position, which is presented to the user as a force feedback applied to the control lever. As the first step in the development of a complex micromechatronic device, a simulated testing environment was prepared. A computer model, comprising dynamic foot characteristics, as well as agonistic and antagonistic muscle groups, substitutes the ankle joint. The model also includes fatiguing of the electrically stimulated muscles. For experimental purposes an actuated control lever was built. The efficacy of the telekinesthetic feedback was evaluated in a group of six healthy persons.

Ankle Joint↗
PubMedDate not supplied

Development and evaluation of a two-dimensional electrocutaneous cognitive feedback system for use in paraplegic standing.

Fatigue of electrically activated paralysed muscles is a major factor limiting the duration of functional electrical stimulation (FES) supported paraplegic standing. Fatigue can be significantly delayed by changing the posture. Since paralysed individuals are deprived of proprio- and exteroception from the lower limbs they are not aware of the posture and loading of their paralysed legs. If suitable cognitive feedback (CF) information about posture in the sagittal and frontal planes is provided, they might be able to successfully exercise posture switching. A two-dimensional electrocutaneous CF system was developed. Relative limb loading and the location of the weighted centre of pressure were selected as informational variables. Discrete encoding schemes in the form of spatial and frequency codes were employed and the informational signals were divided into three sub-regions. The ability to correctly interpret the CF was investigated using one- and two-dimension tracking tests in three paralysed subjects, each of whom were studied over five consecutive days. All three subjects were able to use the CF in one-dimension tests. Two subjects could do the same also in two-dimension tests. The encoding scheme which was developed to communicate the selected biomechanical variables proved to be easily understood and thus appropriate for use in paraplegic standing.

Adult↗
PubMedDate not supplied

Paraplegics standing up using multichannel FES and arm support.

The suitability of multichannel functional electrical stimulation (FES) during the standing-up manoeuvre for therapeutic home use was investigated. Two spinal cord-injured subjects (SCI) participated in the study. Ankle plantar flexors, knee extensors and hip extensors were stimulated. The amplitude of the stimulation pulses depended on the current phase of raising. The sit-to-stand process was divided into three phases by detecting characteristic events in the vertical handle reaction force. It was found that the multichannel FES did not contribute to the decrease of the arm support force when compared with stimulation of knee extensors only. However, stimulation of the hip extensors could speed up the raising process. Increased repeatability and faster standing up were observed when the stimulation began before the start of raising.

Arm↗
PubMedDate not supplied

Standing-up robot: an assistive rehabilitative device for training and assessment.

In this paper a robotic assistive device is presented, aimed at assisting physically impaired individuals when rising from a sitting to a standing position. The robotic device is designed as a three degrees of freedom (3-DOF) mechanism supporting the subject under the buttocks. The device is driven by an electrohydraulic servosystem capable of operating in multiple control modes. It is instrumented with a sensory system providing information about the standing-up parameters. Evaluation of the standing up assistive device was accomplished in robot-supported rising trials of a paraplegic subject. The experiments demonstrated that stable risings in different standing - up manoeuvres were achieved. The measurement results revealed the role of the arm support and the support of the artificially evoked moments in the paralysed lower extremities during rising. The results show that the device can be used efficiently for training and evaluation of standing up manoeuvres.

Adult↗
PubMedDate not supplied

A quantitative gait assessment method based on energy exchange analysis during walking: a normal gait study.

In this paper a gait efficiency assessment method, Gait Energy Efficiency Index (GEEI), which can be used in evaluation of the progress of the rehabilitation process in disabled persons, is proposed and described. The method is based on calculation of cross correlation between normalized time courses of kinetic and potential energy of the body's centre of mass (COM). We hypothesized that GEEI in energetically optimal normal walking should be high and invariable of gait speed. The method was tested on twelve healthy subjects walking at three different speeds and contrasted to five established gait energy consumption assessment methods. The results showed that GEEI in normal walking is close to 1 regardless of walking speed.

Adult↗
PubMedDate not supplied

Voluntary telemetry control of functional electrical stimulators.

With the assistance of crutches and functional electrical stimulation (FES) we are able to restore standing and simple gait in some spinal cord injured (SCI) patients. In the present rehabilitative systems the patient divides the gait cycle into 'stance' and 'swing' phase by using pushbuttons mounted in the handles of the crutches. These are then hard wired to the functional electrical stimulator. We present the development and evaluation of a surface mount technology based telemetry system that provides reliable and interference resistant wireless control of FES assisted walking. The system makes use of radio frequency carriers operating at a frequency of 40 MHz. Crutch pushbutton signals are coded and transferred from the transmitter placed in the crutch to the receiver which is firmly attached to the patient's waist and connected to the stimulator. The telemetry system was found to be of special importance for both complete and incomplete SCI subjects and is currently in use at the Rehabilitation Institute of the Republic of Slovenia.

Activities of Daily Living↗