Model for surface-roughness parameters determination in a virtual machine shop environment

With the help of the computer simulation technology, the virtual machining simulation system of NC machine tool was built based on the integrated simulation module of the UG NX software. Through setting the NC machine parameter of the virtual machining system, the machining process simulation of the typical parts in virtual environment was completed, which implements the collision and interference checking in the process of NC machining and verifies the correctness of NC programs. Finally, the simulation results prove that the assembly modeling method of virtual simulation system for the NC machining is feasible, and the simulation of machining process can effectively determine the mutual interference problem of the machining system, which lays the foundation for effectively preventing the collision accident.

The current study concerns the identification of possible differences in perception between the virtual and the real world in terms of the effect on brain activity. For this reason, an EEG device was used to capture participants' brain activity in different brain areas during their exposure to different virtual and real environments. The environments considered in this study portray a classroom environment with a scenario suitable for teacher training and professional development. The first aim of the experiment is to investigate if exposure to a virtual environment can affect motor, cognitive or other function of the users, and the second aim is to test if the graphics content and nature of such an environment can influence the user experience. During the study, the optimum duration of exposure in a virtual environment was also assessed by measuring the time that the brain needs to perceive and adapt to the new state. Our results, consisting of EEG data analyzed in 10 Regions of Interest (ROIs) and responses from an Igroup Presence questionnaire, indicated a significant difference in each brain area, especially in the frontal and occipital region, when a participant was exposed to a non-realistic virtual environment, compared to a realistic one, highlighting the impact of the selected virtual environment design. The results of the experiment can play an important role in defining the characteristics of optimal virtual environments for virtual reality-based training applications.

In this paper, an innovative approach to controlling temperature was made. Using Unity as our chosen platform, we crafted a virtual environment, that replicates the real-world temperature change dynamics. For this, a virtual environment mimics an enclosed area with a virtual heat source. Additionally, this environment’s area and air density were also taken into consideration. Then, a virtual sensor and cooler were added for detecting and adjusting the environment temperature. Finally, the ML agent package was integrated for controlling temperature with RL. This integration consisted of adding a script that inherits from the agent class and has environment, sensor, and cooler as variables. In each epi-sode, there was a time duration in which both environment's temperature change was calculated and the reward was set to be given only when the environment's temperature was at a certain range. The empirical findings show the efficiency of our approach, show-casing the system's ability to adapt and optimize temperature regulation parameters over successive iterations. By successfully integrating Unity and ML agents, our study under-scores the transformative potential of harnessing virtual environments and machine learning for advancing temperature control technologies. Keywords: unity, ml agents, temperature control, virtual environment, reinforcement learning.

A virtual machine is a software replica of an underlying real machine. Multiple virtual machines can operate on the same host machine concurrently, without interfere each other. Such concept is becoming valuable in production computing systems, due to its benefits in terms of costs and portability. As they provide a strong isolation between the virtual environment and the underlying real system, virtual machines can also be used to improve the security of a computer system in face of attacks to its network services. This work presents a new approach to achieve this goal, by applying intrusion detection techniques to virtual machine based systems, thus keeping the intrusion detection system out of reach from intruders. The results obtained from a prototype implementation confirm the usefulness of this approach.

A real-time integrated calibration system for virtual reality environments has been developed that enables accurate electromagnetic tracking of user motions. Electromagnetic tracking systems suffer degradation in accuracy due to the presence of metals and other electromagnetic distortions in the environment. Calibration of the virtual environment to account for these distortions is essential for VR applications in engineering where correlation between the virtual environment and the physical world is important. The major contribution of the paper is the presentation of a comprehensive methodology for calibrating the VR space, the numerical/mathematical techniques proposed for the calibration, and case studies for calibration accuracy and execution time to enable using these techniques in real time in an integrated setup.

A robot belt grinding system provides promising prospects for relieving hand grinders from their noisy work environment, as well as for improving machining accuracy and product consistency. However, for a manufacturing system with a flexible grinder, controlling the robot to perform precise material removal from free-form surfaces is a challenge. In the belt grinding process, material removal is related to a variety of factors, such as workpiece shape, contact force, and robot velocity. Some factors of the grinding process, such as belt wear, are time-variant. To achieve the desired removal in the grinding process, an intelligent control method for the industrial robot is proposed in this paper. First, an adaptive grinding process model that can track discontinuous changes in working conditions is constructed to precisely predict material removal in accordance with in situ measurement data. With incorporated prior knowledge, the method considerably improves model accuracy, which worsens when new samples from an in situ measurement are insufficient or are unevenly distributed under new working conditions. After this, an online trajectory generation method for the robot control parameters is proposed. By calculating the optimal control parameters in real time, the control transition process is shortened and its negative effect on grinding quality is reduced. Finally, the preliminary grinding experiments validate the workability and effectiveness of the proposed control method.

In this paper, a different way to construct the virtual reality system is put forward. Based on Virtools technology, a virtual lab for mechanical experiment is built. Machining scenes and assembly scene are contained in the system. The simulation of machining process and assembly using tools is implemented through interacting with the computer. A method using both the building blocks and the Virtools Script Language corporately is realized. The feeling of reality is also increased by mixing of multimedia such as audio, video and the virtual environment. All these can be used either in college education or practice training to acquire knowledge about the machines and the related operations, and avoid the potential dangers in the real process.

Over the past decade, wide-area distributed computing has emerged as a powerful computing paradigm. Virtual machines greatly simplify wide-area distributed computing by lowering the abstraction to benefit both resource users and providers. A virtual execution environment consisting of virtual machines (VMs) interconnected with virtual networks provides opportunities to dynamically optimize, at run-time, the performance of existing, unmodified distributed applications without any user or programmer intervention. We have formalized the adaptation problem in virtual execution environments and shown that it is NP-hard to both, solve and approximate within a factor of m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2-δ</sup> for any δ > 0, where m is the number of edges in the virtual overlay graph. We also designed and evaluated greedy adaptation algorithms and found them to work well in practice.

This paper shows the early research findings of utilizing a virtual reality environment as an educational tool for the operation of a computerized numerical control (CNC) milling machine. Based off of previous work, the Advanced Virtual Machining Lab (AVML), this project features an environment in which a virtual CNC machine is fully operable, designed to allow STEM students and training professionals to learn the use of the CNC machine without the need to be in a physical lab. Users operate in the virtual environment using an immersive virtual reality headset (i.e. Oculus Rift) and standard input devices (i.e. mouse and keyboard), both of which combined make for easy movement and realistic visuals. On-screen tutorials allow users to learn about what they need to do to operate the machine without the need for outside instruction. While designing and perfecting this environment has been the primary focus of this project thus far, the research goal is to test the ease of use and the pedagogical effectiveness of the immersive technology as it relates to education in STEM fields. Initial usability studies for this environment featured students from a CAD/CAM-Theory and Advanced Applications (ME 54600) course at a Midwestern urban institution. Results from the study were tabulated with a survey using a four-point Likert scale and several open-ended questions. Findings from the survey indicated that the majority of users found the environment realistic and easy to navigate, in addition to finding the immersive technology to be beneficial. Many also indicated that they felt comfortable navigating the environment without the need for additional assistance from the survey proctors. Full details on the usability study, including data and discussion, can be found in this paper. The general consensus from the study was that, while some features needed refinement, the immersive environment helped them learn about the operation of a CNC machine. An additional comparative study will be undertaken to evaluate pedagogical effectiveness.

Unlike physical systems consisting of hardware, virtual machines are conceptual computers in logical configurations made of software. Although programs implemented in virtual machine environments have platform-independent characteristics, their performance is low in terms of implementation speed and they cannot implement those parts that are dependent on the platform by themselves. In addition, they have the shortcoming of being unable to reuse those libraries and programs that are written in the native language. In the present paper, a study for provision of native interfaces of smart virtual machines (SVMs) is introduced. The native interfaces of existing systems were analyzed to define a native interface protocol for SVMs, an interface definition language and an interface generator were designed for effective use of the defined native interface protocol, and the operation of the implemented native interface was verified through experiments. The native interface proposed in the present paper consists of items and rules necessary for information transmission between virtual machine environments and native environments, interface definition files necessary to deliver information on native functions to virtual machines, and functions and data types necessary for native environment to receive information from virtual machine environments. Through such native interfaces, virtual machine environment developers can use environment-dependent function without modifying virtual machine environments.

The needs for three-dimensional (3D) visualization and navigation within 3D-GIS environment are growing and expanding rapidly in a variety of fields. In a steady shift from traditional two-dimensional (2D) GIS toward 3D-GIS, a great amount of accurate 3D data sets (e.g. city models) have become necessary to be produced in a short period of time and provided widely on the market. This requires a number of specific issues to be investigated, e.g. 3D routing accuracy, appropriate means to visualize 3D spatial analysis, tools to effortlessly explore and navigate through large models in real time, with the correct texture and geometry. There had been a lot of study on 3D landscapes, urban and city models. The rapid advancement in science and technology had opened wide options for a change and development of current methods and concepts. Virtual Reality (VR) is one of those developments, which gives the sense of feel in virtual environment. It enables users to visualize, make query and exploring 3D data. Such system can, not only help laymen, who often have trouble in understanding or interpreting complex data, but they also can help experts in decision making. The objective of this paper is to discuss some initial requirements of the proposed solution towards 3D-GIS. Eventually, this paper will serve as a starting point for a more challenging research idea. The focus of this research is to investigate and implementing 3D navigation techniques and solutions for 3D-GIS. Investigation on the support of navigation in real world environment will be carried out. This will include a research on the benefits of using 3D network model (non-planar graph) compared to 2D, how to use visual landmarks in route descriptions and using 3D geometry to get more accurate routing (in buildings, or in narrow street, etc). And as for implementation, a GUI provides the users with means (e.g. fill-out forms) to specify SQL queries interact and visualize 3D outcomes in virtual reality environment. This has opened up the ability to distribute and navigate accurately in 3D virtual worlds. The initial study on Klang Valley will go through data conversion processes from different formats like Laser, VRML, CAD and Shape 3D in a first person view environment using a developed system using VRML, JAVA and .Net compiler. The dataset structure will be in the form of various 2D, 2.5D and 3D array of height fields.

This paper presents the creation of an assembly simulation environment with multisensory feedback (auditory and visual), and the evaluation of the effects of auditory and visual feedback on the task performance in the context of assembly simulation in a virtual environment (VE). This VE experimental system platform brings together complex technologies such as constraint-based assembly simulation, optical motion tracking technology, and real time 3D sound generation technology around a virtual reality workbench and a common software platform. A peg-in-a-hole and a Sener electronic box assembly task have been used as the task cases to conduct the human factor experiment, using sixteen participants. Both objective performance data (i.e., task completion time, TCT; and human performance error rate, HPER) and subjective opinions (i.e., questionnaires) on the utilization of auditory and visual feedback in a virtual assembly environment (VAE) have been gathered from the experiment. Results showed that the introduction of auditory and/or visual feedback into VAE did improve the assembly task performance. They also indicated that integrated feedback (auditory plus visual) offered better assembly task performance than either feedback used in isolation. Most participants preferred integrated feedback to either individual feedback (auditory or visual) or no feedback. The participants' comments demonstrated that nonrealistic or inappropriate feedback had a negative effect on the task performance, and easily made them frustrated.

Event Abstract Back to Event Effect of visual field motion on vestibulo-myogenic response during upright stance: A pilot study Yawen Yu1, 2* and Emily A. Keshner1 1 Temple University, Physical Therapy, United States 2 Shriners Hospitals for Children - Philadelphia, United States BACKGROUND Maintaining upright stance requires the continuous update on sensory information from the primary systems in order to estimate the current state of postural orientation (Peterka, 2002). While each sensory system is responsible for unveiling a specific aspect of body motion, changes in one sensory system can also alter sensory input from another sensory system. This process of adjusting sensory contributions to balance control is referred to as sensory reweighting (Asslander & Peterka, 2014). Sensory reweighting would explain why the magnitude of the postural response due to galvanic vestibular stimulation (GVS) is dependent upon non-vestibular sensory signals (Fitzpatrick & Day, 2004). A much greater postural response can be elicited by GVS, when visual information is made unavailable (Welgampola & Colebatch, 2001). Individuals standing quietly in an immersive virtual environment where the visual surround is continuously moving exhibit postural sway in the direction of the visual flow (Wang, Kenyon, & Keshner, 2010). Thus, vestibular reafference could be modulated by visual flow as it is by fear of falling (Naranjo, Allum, Inglis, & Carpenter, 2015) and weakened muscle strength around the ankle (McIntosh, Power, & Dalton, 2018). The purpose of the current study was to explore whether vestibular reafference would be modulated by visual field motion. Results of this study provide a physiological interpretation for changes in the postural response due to visual field motion. METHODS Subjects: Eight healthy young adults (8 females; 28.0 ± 6.0 years) with no history of neurological disorder gave informed consent to participate in the current study. All subjects had no known history of vestibular or hearing deficit. All participants had a minimum of 20/40 corrected vision. The experimental protocol was approved by the Temple University Ethics Board. Using the Rod-and-Frame test, all participants were identified as visually independent (Yu, Lauer, Tucker, Thompson, & Keshner, 2018). Virtual Environment: The immersive virtual environment consisted of three screens facing the front, right, and left of the subject. The overall dimension of the virtual environment was 3.5m (width), 3.5m (depth), and 6.1m (height). One Panasonic PT-DX610 DLP-based projectors positioned behind each screen projected a full-color field with the resolution of 1024x768 pixels at a 60 Hz refresh rate. The image of the virtual environment was created in Unity (Unity Technologies SF, San Francisco, CA, USA). Vestibular Evoked Myogenic Potential (VEMP): Acoustic air-conducted stimulation consisting of 500Hz, 125dB SPL tone bursts, with 1ms rise/fall time, 2ms plateau, at a repetition rate of 5 Hz, was delivered monaurally though in-ear earphones (ER-3C, Etymotic Research Inc., Elk Grove Village, IL, USA). The electromyogram (EMG) signals representing cervical vestibular evoked myogenic potential (cVEMP) responses were recorded with disposable, self-adhesive, pre-gelled, Ag/AgCl electrodes with 40-inch safety leadwires (GN Otometrics, Schaumbaurg, IL, USA), which were amplified (2500x) and band-pass filtered (20 – 2000Hz) for cVEMPs. A non-inverting electrode was placed at the mid-point of the sternocleidomastoid (SCM) muscle on each side. An inverting electrode was placed at the sternoclavicular junction on each side. A ground electrode was placed on the manubrium sterni. Procedure: Participants were instructed to perform quiet stance in the center of the virtual environment. For left cVEMP testing, for example, participants were asked to look over the right shoulder to face the front screen with their body parallel to the left screen and actively contract the left SCM throughout the trial. During each 20-second trial, the visual field motion was kept either stationary (EO) or continuously rolling about the nasion-to-inion axis (RU) at 30°/s. Additionally, the acoustic air-conducted stimulation (100 tone-bursts) was delivered over the 20-second period. Three trials were performed for each condition on each side. Response parameters: The cVEMP waveform consists of a positive peak (p13), identified as the first distinctive valley in the waveform that appears 11ms – 16ms post tone burst, and a negative peak (n23), identified as the first distinctive peak in the waveform that appears 18ms – 26ms post tone burst. Mean values for cVEMP latencies and amplitudes were calculated separately for p13 and n23; peak-to-peak (p13-n23) amplitudes were also calculated. Muscle background activity of each SCM was calculated using the area under the curve of the rectified EMG over the 10ms window pre-stimulus. Statistical Analysis: Paired-sample t-tests were used to compare differences between EO and RU conditions for all dependent measures with the level of statistical significance set at p = 0.05. RESULTS A significant effect of visual field motion emerged in cVEMP amplitudes (p=.014). Specifically, the p13 amplitudes were significantly reduced by the RU visual scene condition (Figure 1; EO: 21.1±4.2 uV; RU: 17.7±3.7 uV). No significant differences between the stationary and roll visual conditions were found in n23 amplitudes, p13 and n23 latencies, and p13-n23 peak-to-peak amplitudes or in the background EMG activity (ps>.05). DISCUSSION Changes in the magnitude of the cVEMP suggest that vestibular reafference was modulated by visual field motion in the virtual environment even though all of the healthy participants in this study were identified as visually independent. To our knowledge, this is the first study to elicit and record VEMPs during upright stance with different conditions of visual field motion. These results provide a foundation for future studies examining vestibulo-myogenic responses in individuals with visual dependence due to neurological disorders (e.g., stroke, cerebral palsy). Comparison of vestibulomyogenic responses as a function of illusion of self-motion due to visual field motion (or vection) could further explain how the nervous system weights these signals in the natural environment. Figure 1 Acknowledgements This work is supported by the Shriners Hospitals for Children Postdoctoral Fellowship (#84308-PHI) to Yawen Yu. References Asslander, L., & Peterka, R. J. (2014). Sensory reweighting dynamics in human postural control. J Neurophysiol, 111(9), 1852-1864. doi: 10.1152/jn.00669.2013 Fitzpatrick, R., & Day, B. (2004). Probing the human vestibular system with galvanic stimulation. Journal of Applied Physiology, 96, 2301-2316. doi: 10.1152/japplphysiol.00008.2004. McIntosh, E. I., Power, G. A., & Dalton, B. H. (2018). The vestibulomyogenic balance response is elevated following high-intensity lengthening contractions of the lower limb. Neurosci Lett. doi: 10.1016/j.neulet.2018.03.056 Naranjo, E. N., Allum, J. H., Inglis, J. T., & Carpenter, M. G. (2015). Increased gain of vestibulospinal potentials evoked in neck and leg muscles when standing under height-induced postural threat. Neuroscience, 293, 45-54. doi: 10.1016/j.neuroscience.2015.02.026 Peterka, R. J. (2002). Sensorimotor integration in human postural control. J Neurophysiol, 88(3), 1097-1118. Wang, Y., Kenyon, R. V., & Keshner, E. A. (2010). Identifying the control of physically and perceptually evoked sway responses with coincident visual scene velocities and tilt of the base of support. Exp Brain Res, 201(4), 663-672. doi: 10.1007/s00221-009-2082-0 Welgampola, M. S., & Colebatch, J. G. (2001). Vestibulospinal reflexes: quantitative effects of sensory feedback and postural task. Exp Brain Res, 139(3), 345-353. Yu, Y., Lauer, R. T., Tucker, C. A., Thompson, E. D., & Keshner, E. A. (2018). Visual dependence modifies postural sway responses to continuous visual field motion in individuals with cerebral palsy. Dev Neurorehabil. doi: 10.1080/17518423.2018.1424265 Keywords: virtual environment, posture and balance, sensorimotor integration, Vestibular evoked myogenic potential (VEMP), Vection Conference: 2nd International Neuroergonomics Conference, Philadelphia, PA, United States, 27 Jun - 29 Jun, 2018. Presentation Type: Oral Presentation Topic: Neuroergonomics Citation: Yu Y and Keshner EA (2019). Effect of visual field motion on vestibulo-myogenic response during upright stance: A pilot study. Conference Abstract: 2nd International Neuroergonomics Conference. doi: 10.3389/conf.fnhum.2018.227.00086 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 03 Apr 2018; Published Online: 27 Sep 2019. * Correspondence: PhD. Yawen Yu, Temple University, Physical Therapy, Philadelphia, PA, United States, yawen.yu@colostate.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Yawen Yu Emily A Keshner Google Yawen Yu Emily A Keshner Google Scholar Yawen Yu Emily A Keshner PubMed Yawen Yu Emily A Keshner Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

The current study was done to investigate the effect of varying the update rate of a computer-generated simulation (5, 10, 15, 20, 25 Hz) on the sense of presence within stereoscopic virtual environments. Thirteen subjects navigated a virtual representation of Stonehenge and were asked to search for a rune, inscribed upon the wall of one of Stonehenge's edifices. After performing the search task, subjects completed a questionnaire designed to assess their level of presence within the virtual environment. The results indicated that the subjective report of presence within the virtual environment was significantly less using an update rate of 5 and 10 Hz when compared to update rates of 20 and 25 Hz. Furthermore, the reported level of presence using a 15 Hz update rate was similar to the reported level of presence using update rates of 20 and 25 Hz thus indicating that computational resources could be saved using a slower update rate while maintaining a given level of presence. In addition, a factor analysis procedure indicated that the 13 questions designed to assess the subjects sense of presence within virtual Stonehenge could be grouped into three factors: (1) virtual presence, (2) navigation within the virtual environment, and (3) knowledge of real world surroundings while in the virtual world. Finally, comments on a descriptive model of presence within virtual environments are presented.

Hadoop MapReduce as a service from cloud is widely used by various research, and commercial communities. Hadoop MapReduce is typically offered as a service hosted on virtualized environment in Cloud Data-Center. Cluster of virtual machines for MapReduce is placed across racks in Cloud Data-Center to achieve fault tolerance. But, it negatively introduces dynamic/heterogeneous performance for virtual machines due to hardware heterogeneity and co-located virtual machine's interference, which cause varying latency for same task. Alongside, curbing number of intermediate records and placing reduce tasks on right virtual node are also important to minimize MapReduce job latency further. In this paper, we introduce Multi-Level Per Node Combiner to minimize the number of intermediate records and Dynamic Ranking based MapReduce Job Scheduler to place reduce tasks on right virtual machine to minimize MapReduce job latency by exploiting dynamic performance of virtual machines. To experiment and evaluate, we launched 29 virtual machines hosted in eight different physical machines to run wordcount job on PUMA dataset. Our proposed methodology improves overall job latency up to 33% for wordcount job.