Biomedical subjects

Marko Munih

Publications and source records attributed to Marko Munih.

4 recordsLinked to original sources

PubMed2006

An identification technique for evaluating body segment parameters in the upper extremity from manipulator-hand contact forces and arm kinematics.

OBJECTIVE: To show that it is possible to determine segment masses and segment centers of mass by measuring manipulator-hand contact forces and joint angles during upper extremity movement. BACKGROUND: The method serves as a quick subject specific body segment parameter evaluation technique. Clinically we see this method as an alternative upper extremity body segment parameter evaluation study especially useful in rehabilitation treatment activities. METHODS: The experiment is based on coupling the human arm with a robotic manipulator which is then used for imposing a specified sagittal plane trajectory. Joint angles and forces in the contact point serve as input to the identification procedure. For verification purposes the proposed identification procedure was first performed on a mechanical arm. Afterwards a low velocity trajectory was imposed into all joints of the human upper extremity, with very small angular deviations. Within this small angular region the arm was assumed to be represented as a linear system. FINDINGS: The outcome of the identification procedure is an estimate of masses and center of mass coordinates for the lower arm and palm segments, their products for the upper arm and the passive moments around the measured angle of all joints in the sagittal plane. The results obtained for three particular human arms are eventually compared to the average population based literature. CONCLUSION: From the clinical point of view the study can become useful for biomechanical evaluation and for evaluating biomechanical properties of lower extremities or other body segments. This method may also provide a foundation to measuring body segment moments of inertia and joint viscoelastic parameters.

Adult↗

PubMed2006

Application of haptic interface for finger exercise.

A haptic device with two active degrees-of-freedom and a tendon-driven transmission system was designed, later on constructed, and submitted to testing. It was embodied as a lightweight mechanism with a small workspace that wraps the finger workspace and can generate forces up to 10 N suitable for finger exercise. The control loop and the user application were implemented on a personal computer in the Microsoft Windows environment. Along with the device, application covering several different experiment types was developed. The system was evaluated in a group of stroke patients during a one-month period of therapy. Results for two types of experiments are presented. The progress of the patient affected hand side was found to be greater than for the one nonaffected, however, the mean values of the relevant parameters on the nonaffected side of patients are higher than those for the affected side. Results were compared to the motor component of functional independence measure (M-FIM) measured clinical scale.

Adult↗

PubMed2004

Unsupported standing with minimized ankle muscle fatigue.

In the past, limited unsupported standing has been restored in patients with thoracic spinal cord injury through open-loop functional electrical stimulation of paralyzed knee extensor muscles and the support of intact arm musculature. Here an optimal control system for paralyzed ankle muscles was designed that enables the subject to stand without hand support in a sagittal plane. The paraplegic subject was conceptualized as an underactuated double inverted pendulum structure with an active degree of freedom in the upper trunk and a passive degree of freedom in the paralyzed ankle joints. Control system design is based on the minimization of a cost function that estimates the effort of ankle joint muscles via observation of the ground reaction force position, relative to ankle joint axis. Furthermore, such a control system integrates voluntary upper trunk activity and artificial control of ankle joint muscles, resulting in a robust standing posture. Figures are shown for the initial simulation study, followed by disturbance tests on an intact volunteer and several laboratory trials with a paraplegic person. Benefits of the presented methodology are prolonged standing sessions and in the fact that the subject is able to maintain voluntary control over upper body orientation in space, enabling simple functional standing.

Algorithms↗

PubMed2003

Quantification of shoulder and elbow passive moments in the sagittal plane as a function of adjacent angle fixations.

The goal of this study was an assessment of the shoulder and elbow joint passive moments in the sagittal plane for six healthy individuals. Either the shoulder or elbow joints were moved at a constant speed, very slowly throughout a large portion of their range by means of an industrial robot. During the whole process the arm was held fully passively, while the end point force data and the shoulder, elbow and wrist angle data were collected. The presented method unequivocally reveals a large passive moment adjacent angle dependency in the central angular range, where most everyday actions are performed. It is expected to prove useful in the future work when examining subjects with neuromuscular disorders. Their passive moments may show a fully different pattern than the ones obtained in this study.

Adult↗