Andrzej Grabowski

Usability Evaluation of VR Interface for Mobile Robot Teleoperation

This article presents the results from research in which 3 different remote control interfaces were compared to assess the impact of interface structure on the performance of the operator for remotely controlled mobile inspection robots. The primary control interface of a mobile robot consists of a head-mounted display, data gloves for gripper control, joystick for movement control of the robot platform, and a motion tracking system for measuring head orientation and hand position. In order to compare different control interfaces, an additional system, based on a Liquid Crystal Display monitor and joystick, was prepared. Results of this study show that the use of virtual reality techniques in the interfaces of mobile inspection robots increases operator productivity, the level of spatial presence, and distance evaluation while facilitating the execution of tasks, as well as improving and speeding up their execution and reducing the operator’s time needed to adapt to the control interface. The latter is achieved with the increased level of intuitive control while ensuring comfort.

Vision safety system based on cellular neural networks

This work is dedicated to develop a safety measurement for human–machine cooperative system, in which the machine region and the human region cannot be separated due to the overlap and the movement both from human and from machines. Modern production processes become more and more flexible. Therefore, there is a need that devices used in workplace also support flexibility as much as possible. Such characteristics have vision-based protective devices. We present a neural system for the advanced recognition of danger situation for safety control. The sequence of the images from two cameras located above the robot is presented to the system of cellular neural networks (CNNs) realized in the PC computer. They detect a new object appearing in a safety field, define its position with respect to the robot arm and perform the feature extraction of its image. Experiments conducted using artificial images (virtual environment) and low-quality images (internet cameras) indicate that our system can work in a real time and detect successively dangerous situations. We have found that the CNN is unable to detect a new object properly in the presence of high level of noise as a result of percolation type phase transition. An example of possible application of the system is presented.

Heart rate variability (HRV) during virtual reality immersion

The goal of the study was assessment of the hour-long training involving handling virtual environment (sVR) and watching a stereoscopic 3D movie on the mechanisms of autonomic heart rate (HR) regulation among the subjects who were not predisposed to motion sickness. In order to exclude predispositions to motion sickness, all the participants (n=19) underwent a Coriolis test. During an exposure to 3D and sVR the ECG signal was continuously recorded using the Holter method. For the twelve consecutive 5-min epochs of ECG signal, the analysis of heart rate variability (HRV) in time and frequency domains was conducted. After 30 min from the beginning of the training in handling the virtual workstation a significant increase in LF spectral power was noted. The values of the sympathovagal LF/HF index while sVR indicated a significant increase in sympathetic predominance in four time intervals, namely between the 5th and the 10th minute, between the 15th and the 20th minute, between the 35th and 40th minute and between the 55th and the 60th minute of exposure.

Stereovision Safety System for Identifying Workers’ Presence: Results of Tests

This article presents the results of extensive tests of a stereovision safety system performed using real and artificial images. A vision based protective device (VBPD) analyses images from 2 cameras to calculate the position of a worker and moving parts of a machine (e.g., an industrial robot’s arm). Experiments show that the stereovision safety system works properly in real time even when subjected to rapid changes in illumination level. Experiments performed with a functional model of an industrial robot indicate that this safety system can be used to detect dangerous situations at workstations equipped with a robot, in human–robot co-operation. Computer-generated artificial images of a workplace simplify and accelerate testing procedures, and make it possible to compare the effectiveness of VBPDs and other protective devices at no additional cost.

Intelligent Agents System for Evacuation Processes Modeling

In the paper an intelligent agents system is used for modeling evacuating processes of rooms and buildings. The motion of each agent is described using Langevin equation with the social force term, which make possible to take into account mental component in agents motion - connected with the level of hazard. In numerical simulations it is possible to observe the trajectories of agents and emergent phenomena accompanying evacuation. Calculation of times of evacuation for different rooms and buildings enable to discuss factors influencing the effectiveness of evacuation.

Workstations for people with disabilities: an example of a virtual reality approach

This article describes a method of adapting workstations for workers with motion disability using computer simulation and virtual reality (VR) techniques. A workstation for grinding spring faces was used as an example. It was adjusted for two people with a disabled right upper extremity. The study had two stages. In the first, a computer human model with a visualization of maximal arm reach and preferred workspace was used to develop a preliminary modification of a virtual workstation. In the second stage, an immersive VR environment was used to assess the virtual workstation and to add further modifications. All modifications were assessed by measuring the efficiency of work and the number of movements involved. The results of the study showed that a computer simulation could be used to determine whether a worker with a disability could access all important areas of a workstation and to propose necessary modifications.

EPIDEMIC CONTROL IN A HIERARCHICAL SOCIAL NETWORK

The phenomenon of epidemic spreading in a population with a hierarchical structure of interpersonal interactions is described and investigated numerically. The SIR model with incubation time is used. In our model the localization of individuals in different social groups, the effectiveness of different interpersonal interactions and the mobility of a contemporary community are taken into account. The influence of different control methods on the spreading process is investigated as a function of different initial conditions. The cost-effectiveness of mass preventive random vaccinations, target vaccinations and sick leaves are compared. A critical range of vaccinations, sufficient for suppressing of an epidemic is calculated. The results of numerical calculations are similar to the solutions of the master equation for the spreading process.

Rękawica rzeczywistości wirtualnej : budowa systemu śledzenia ruchu ręki oraz palców wykorzystywanego w technice rzeczywistości wirtualnej

Publikacje opracowano na podstawie wynikow realizacji projektu numer DOB – BIO7/22/02/2015 pn.: „Symulatory szkoleniowe w zakresie zwalczania pozarow wewnetrznych” (CYBERFIRE) finansowanego przez Narodowe Centrum Badan i Rozwoju w latach 2015-2018.

Sense of Touch in Training Tasks Demanding High Precision and Short Time of Execution

Engaging the sense of touch in virtual environments is a challenging and important issue. Currently, the most common way to address this issue is the use of a set of actuators that restrict hand movement. This article presents an alternative method to track physical surrogate representations of virtual objects using a vision-based system. Using real objects that can be manipulated by a person immersed in a virtual environment is an alternative to expensive robotized haptic systems. Moreover, this technique allows the user to move objects over long distances. Research conducted with 30 volunteers shows that the sense of touch can significantly reduce the execution time of tasks demanding high precision. Despite this decrease in execution time, an increase in precision has been observed. The conclusion of this article looks at the pros and cons of the use of physical surrogates for virtual objects, for example, less time needed for virtual reality-based training with the use of physical surrogates.

Simulation study on evacuation from buildings

In the paper the results of simulation study on evacuation from building using intelligent agents system and experiment during drill evacuation from a building are presented. Each agent uses movement strategies based on algorithms integrating data coming from many different sources, eg. Langevin equation with the social force term describing agents mental component are used. In numerical simulations it is possible to observe the trajectories of agents. Reuse of information obtained by different agents decreases computation time.