Aleksandar Veg

Walkaround: Mobile Balance Support for Therapy of Walking

We describe here the Walkaround, a new rehabilitation device that allows walking without hand support of individuals with limited ability to control posture. The design of this device was motivated by the recent development of functional electrical therapy of walking in individuals with hemiplegia, who in many cases need postural and body weight assistance while walking. The Walkaround assists humans with a compromised posture, inability to fully support the body weight on one leg, and prevents their falls. These three features are accomplished by an ergonomic lumbar belt being attached to a rigid wheeled frame by a suspensor system. The height of the frame which interfaces the ground by three telescopic bars, the size of the belt, and the pretension of the suspension system, can all be adjusted to complement the size and the needs of the potential user. The amount of body weight support can be adjusted by setting the lengths of telescopic bars and the pretension of the springs in the suspensors. The prototype device was tested on five individuals with hemiplegia. The walking assisted by the Walkaround was significantly faster (Deltav = 0.13 m/s, p < 0.05) in comparison to walking assisted by a therapist. The symmetry index between paretic and non affected leg was decreased (DeltaRstance = -7.4%, p < 0.05, DeltaRswing = -9.2%, p < 0.05, symmetry improved) when walking assisted by the Walkaround. The users and therapists were positive about the performance of the Walkaround. The users felt safer and the therapists were relieved from the physical effort allowing them to concentrate more on assisting a nearly normal walking pattern.

Gait training of poststroke patients assisted by the Walkaround (body postural support).

Improvement in gait abilities is one of the important goals of stroke rehabilitation. The Walkaround is a new postural assistance device for gait training, which allows an early start for gait training. This device provides body postural support (BPS) and trunk orientation by means of a lumbar belt that is connected to a powered rolling walker. We conducted a randomized, single-blinded, 4-week clinical trial of 22 subacute stroke patients with a follow-up period of 6 months. Patients were divided into two identically sized groups: the treatment group (BPS), which was assisted by the Walkaround, and the control (CON) group, which was assisted by conventional means (cane, therapist) during gait training. The objective of the study was to assess whether the Walkaround is more effective than conventional assistance during gait training. The outcome measures were as follows: Barthel index, Fugl-Meyer score for the lower extremities, Berg balance test, and gait speed. Changes in the outcome measures were significant for the Berg balance score after 6 months in both groups and in gait speed among the BPS group at the end of therapy and after 6 months (P<0.05) compared with the same outcome measures at the beginning of the trial. Significant differences were found in gait speed and Berg balance test scores after 4 weeks and in gait speed after 6 months (P<0.05) between the BPS and the CON groups. The results suggest that added postural support by the Walkaround led to limited yet significant changes in gait speed and balance control.

Vibration prediction of pellet mills power transmission by artificial neural network

Purpose The purpose of this study is to establish a vibration prediction of pellet mills power transmission by artificial neural network. Vibration monitoring is an important task for any system to ensure safe operations. Improvement of control strategies is crucial for the vibration monitoring. Design/methodology/approach As predictive control is one of the options for the vibration monitoring in this paper, the predictive model for vibration monitoring was created. Findings Although the achieved prediction results were acceptable, there is need for more work to apply and test these results in real environment. Originality/value Artificial neural network (ANN) was implemented as the predictive model while extreme learning machine (ELM) and back propagation (BP) learning schemes were used as training algorithms for the ANN. BP learning algorithm minimizes the error function by using the gradient descent method. ELM training algorithm is based on selecting of the input weights randomly of the ANN network and the output weight of the network are determined analytically.

Novice Methodology in Preserving Prestressed Cables by Injection of a Special Gel

The most popular grout solutions are based on the application of cement-based materials. They are most frequently being used for grouting of prestressing tendons. Besides, there are some kinds of grease or wax having a good flexibility of the coat layer, while providing adjustability of prestressing force inside strands. Main objective of the paper is to explore the conditions and review other relevant aspects in applying injection gel for covering the prestressing tendons.

Assisting persons after stroke to restore gait: hybrid system

Stroke and spinal cord injury have often an impact on the ability to stand and walk. We present a method for assisting the walking with a combination of the postural assistant (a powered walker providing safety and trunk support) and multi-channel electrical stimulation system that interfaces the paralyzed extremities with surface electrodes. The electrical stimulation is tuned by a sensors driven state-based controller and uses multi-pad electrodes for effective activation of motor systems.

Mechatronic approach to inventing a novel kind of deformeter

Original scientific paper Stress and strain measurements on frames and structures are mainly conducted by the use of strain gauges. A measuring chain applied in such measurements usually consists of strain gauges, amplifiers and data acquisition and logging device. The applicability of such instrumentation mainly depends on its sensitivity measuring repeatability, accuracy and noiseless operation. The key point of this paper is harmonization of measuring properties for the newly invented deformeter with the measuring electronics. Much alike a standard modeling of Mechatronic items, a very specific CLD (Close Loop Deformeter) is optimized throughout coupled modeling, bridging analysis of 3D virtual model and real design of laboratory prototype. Virtual experiment was developed to correspond with actual measurements on the test rig. The idea of rectification factor is introduced into concept of 3D modelling with an innovative CLD research. The focus of the research was kept on the output linearity, measuring range and resolution of the invented deformeter.

Todor Pantelić (1923–1999)

By transforming fundamental theoretical solutions into functional mechanisms, Todor Lazar Pantelic became a pioneer of innovative structural synthesis. Most of his work evolved to the level of patents and industrial products. Professor Pantelic’s specialty was the four-bar chain in innumerable varieties such as walking, imprinting, and shutter mechanisms. The crown of his innovative work was the helical conveyor, theoretically established, patented, designed, and prototyped. Loved and admired by his students and colleagues, he made a point of introducing engineering talent and creativity into the science of machines and mechanisms. He was one of the founders of the International Federation for the Theory of Machines and Mechanisms (IFToMM) and the first president of its Commission for Collaboration of Science and Industry.