Gregorij Kurillo

Static Analysis of Nippers Pinch

The purpose of the study was to present a method for the assessment of finger joint torques in two‐fingered precision grips. The static analysis of various grips is important for the analysis of the mechanics of a human hand and the functional evaluation of grasping. We have built a grip‐measuring device assessing the endpoint forces of two‐oppositional grips. Through the simultaneous use of an optical measuring system and the grip‐measuring device, the finger positions and the grip force acting on the object were obtained. A recursive computational method was used within the proposed static model of the finger to calculate the finger joint torques. In the paper a three‐dimensional static model of the grip is presented and the calculated finger joint torques are shown. The repeatability within subject is analyzed for the assessed grip force and finger joint torques. The estimated joint torques corresponds to the amount of load on the finger joints during the isometric muscle contraction in nippers pinch.

Grasping and manipulation in virtual environment using 3By6 finger device

Realistic simulation of grasping requires accurate modeling of forces and torques on the virtual object produced by fingers in contact. We present isometric 3By6 finger device for multi-fingered grasping in virtual environment (VE). The finger device was designed to measure forces of three fingers. Mathematical model of grasping adopted from the analysis of multi-fingered robot hands was used. The dynamics of the virtual object corresponds to the forces and torques applied by the three fingers. The multi-fingered grasping is demonstrated in four tasks aimed at the rehabilitation of the upper extremities of stroke patients. The tasks include opening of a safe, filling and pouring water from a glass, training of muscle strength with an elastic torus and force-tracking task.

Analysis and Synthesis of Human and Machine Motion at UL FE

The paper gives insight into main fields of analysis and synthesis of human motion in the recent years or into the works that are still under development. After general introduction half to one page of description is provided for each topics. Simple explanations are omitting theoretical details and rather each use one to two pictures to provide quickly accessible information, which is similar to digest structure. Topics are covering from fingers, hand, arms to the lower extremities, measurement systems to the systems using VR and haptics. In conclusion can be found a look into possible future activities..

Assessment of Grip Force Control in Healthy Children and Children with Down Syndrome

The aim of our study was to assess how the grip force control under visual feedback is affected in children with Down syndrome. We designed a tracking-based assessment system. The grip-measuring device developed was used as an input to a tracking task where the children applied the grip force according to the visual feedback from the computer screen. The evaluation was performed in a group of healthy 10 year-old children and a group of seven children with Down syndrome. In our investigation we used two different target signals: ramp to evaluate motor activity with a constant output rate and sinus to assess performance during periodic activity. The children performed the tasks using the lateral grip of their dominant hand. The results show that the healthy children were able to quickly understand the tracking task and performed all tasks with good accuracy. The children with Down syndrome required more time to adjust to the tasks. Based on the approach used during tracking, the children of the Down syndrome group were divided into two separate groups. The children of the first group were able to continuously track the target with somewhat consistent output. The remaining children were not able to understand the tracking task and they repeatedly applied and released the force instead of tracking the target. The results of our study suggest that training by the proposed tracking-based system could improve the performance in some of the children.

Force Tracking System for Training of Hand Function in Stroke Patients

We present a novel tracking system for the rehabilitation of hand function following stroke. The system consists of a compact assessment system with two measuring objects of different shapes, which can be connected to a personal computer for data acquisition and visual feedback. The system was used in connection with four tracking tasks which were applied to train and evaluate patients grip strength and grip force control. The method was applied as a supplemental therapy for 10 post-stroke patients. Training with the tracking system showed significant improvements in the grip force control in 8 out of 10 patients. The patients reduced the tracking error, improved the grasp stability and enhanced the release of the grip. The proposed tracking method is intended to be used to improve and evaluate hand functionality in post-stroke patients and patients after hand injury

Assessment and training of hand dexterity in virtual environment

We designed two systems for assessment and training of force coordination and hand dexterity in virtual environment. In the first system subjects aligned a real object with the reference virtual object. Pose of hand segments and object was assessed with motion tracking system. The study revealed repeatability of trajectories of movements and a significant delay in the movements of joints when close to their mechanical constraints. The second device was designed to simultaneously assess isometric forces applied by the fingers. Mathematical model of grasping was applied to achieve multi-fingered interaction with virtual objects. Several tasks were developed with the aim to improve grip force coordination and increase muscle strength of patients after stroke through repetitive exercises.