Virtual Simulation Environment Research Articles

Modeling and Simulation of the Nutation Drive with Movable Taper Teeth

Background: The nutation drive is being extensively interested due to its ability to achieve a high reduction ratio with a compact structure and the potential for low vibration, high efficiency and design flexibility, while many problems including the difficulty to process the inner bevel gear and less number of teeth in engagement have restricted the development of it. Objective: The purpose of this paper was to propose and analyze a patent about a new nutation drive with movable taper teeth, in which rolling substitutes tooth meshing, the bevel gear processing difficulties and other issues can be avoided. Methods: Based on geometry transformation and the meshing theory, the meshing surface and mathematical equations of the tooth profiles for both the stator and the rotor were developed, enabling the pressure angle to be analyzed in detail. Results: These mathematical models were then verified by kinematics simulation and interference detection in a virtual simulation environment. Further, the verification of the working process of the nutation drive showed that all the simulation values were approximate to the desired value of the designed nutation drive. Conclusion: The study proposed an approach for generating stator and rotor in the nutation drive to provide superior performance in terms of load sharing and contact intensity. Simulation and manufacturing technology of the mechanism were carried out to prove the theoretical equations. The prototype of it has been illustrated to verify the theory and the computer simulation model at the end of this paper.

Investigating the Effect of Cutting Parameters of Ti–6Al–4V on Surface Roughness Based on a SPH Cutting Model

This work establishes a 2D numerical model to simulate the cutting process of workpieces made of Ti–6Al–4V, by applying an improved Smoothed Particle Hydrodynamics algorithm together with a modified constitutive model based on the Johnson–Cook model known as Hyperbolic Tangent (TANH). The location information of the surface particles obtained by the SPH cutting model are used to evaluate the variation trend of surface roughness with different parameters. Parameters that affect the surface roughness are investigated in detail by using the Taguchi method and the SPH cutting model. The present work provides an efficient and cost-effective approach to determine the optimal parameters for cutting processes for Ti–6AL–4V workpieces, through computer simulations in virtual environments, instead of expensive and time-consuming cutting experiments using actual workpieces.

Systemic interventions in regional innovation systems: entrepreneurship, knowledge accumulation and regional innovation

ABSTRACTThe paper employs a regional innovation system concept and divides system failures into three categories: institutional infrastructure, organizational landscape and structural connectedness. To analyze the economic effects of systemic interventions, it employs the VISIBLE model, which allows ex-ante policy experiments to be conducted in a virtual simulation environment. First, the findings show that regional learning and knowledge exchange are accompanied by pronounced non-linearities and combined learning strategies generate highest regional returns. Second, systemic interventions, originally designed to stimulate qualitatively different types of entrepreneurial entries, show – against the backdrop of different regional learning regimes – rather ambiguous effects for both the target firms and the incumbent firms. Finally, it can be seen that interventions designed to affect individual linking behaviour of entrepreneurial firms are effective and robust even for different learning regimes.

A Sim2real method based on DDQN for training a self-driving scale car

The self-driving based on deep reinforcement learning, as the most important application of artificial intelligence, has become a popular topic. Most of the current self-driving methods focus on how to directly learn end-to-end self-driving control strategy from the raw sensory data. Essentially, this control strategy can be considered as a mapping between images and driving behavior, which usually faces a problem of low generalization ability. To improve the generalization ability for the driving behavior, the reinforcement learning method requires extrinsic reward from the real environment, which may damage the car. In order to obtain a good generalization ability in safety, a virtual simulation environment that can be constructed different driving scene is designed by Unity. A theoretical model is established and analyzed in the virtual simulation environment, and it is trained by double Deep Q-network. Then, the trained model is migrated to a scale car in real world. This process is also called a sim2real method. The sim2real training method efficiently handles these two problems. The simulations and experiments are carried out to evaluate the performance and effectiveness of the proposed algorithm. Finally, it is demonstrated that the scale car in real world obtains the capability for autonomous driving.

Speed and Acceleration Control for a Two Wheel-Leg Robot Based on Distributed Dynamic Model and Whole-Body Control

The control technique for generating whole body motions on wheel-leg robot for dynamic locomotion and balance is a challenging topic. In this paper, a whole body dynamic model is built. It consisted by the torso dynamic model, the wheel-leg dynamic model and the contact force constraint between the wheels and the ground. A whole body control frame is proposed which composed by a torso motion controller, two torque solvers, a slippage predictor and an online trajectory generator. The torso controller plans the coupling wrenches between wheel-legs and torso. The torque solvers for every wheel-leg compute joint torques based on the coupling wrenches computed from the torso controller synchronously. The contact forces can be calculated by the slippage predictor based on the joint torques, then a boolean signal will be transmitted to the online trajectories generator to indicate whether the friction cone constraint will be broken. The online trajectory generator can plan reasonable acceleration trajectory with different boolean signals. The efficiency of this control frame is illustrated by several simulations in virtual simulation environment.

E-Learning Proposal Supported by Reasoning based on Instances of Learning Objects

In recent years, new research has appeared in the area of education, which has focused on the use of information technology and the Internet to promote online learning, breaking many barriers of traditional education such as space, time, quantity and coverage. However, we have found that these new proposals present problems such as linear access to content, patronized teaching structures, and non-flexible methods in the style of user learning. Therefore, we have proposed the use of an intelligent model of personalized learning management in a virtual simulation environment based on instances of learning objects, using a similarity function through the weighted multidimensional Euclidean distance. The results obtained by the proposed model show an efficiency of 99.5%; which is superior to other models such as Simple Logistic with 98.99% efficiency, Naive Bayes with 97.98% efficiency, Tree J48 with 96.98% efficiency, and Neural Networks with 94.97% efficiency. For this, we have designed and implemented the experimental platform MIGAP (Intelligent Model of Personalized Learning Management), which focuses on the assembly of mastery courses in Newtonian Mechanics. Additionally, the application of this model in other areas of knowledge will allow better identification of the best learning style of each student; with the objective of providing resources, activities and educational services that are flexible to the learning style of each student, improving the quality of current educational services.

A Memory Model for Emotional Decision-Making Agent in a Game

Virtual characters are an important part of many modern computer games. This paper describes a graph-based memory system designed for artificial agents that also simulate simple emotions. The system was tested using virtual simulation environment and it showed many new and desirable AI behaviours. These behaviours include simple preferences, reactions based on bot’s opinion of a stimuli or improvement of bot’s ability to find objects to interact with.

Vibration control of an active vehicle suspension systems using optimized model-free fuzzy logic controller based on time delay estimation

This paper presents a new model-free fuzzy logic controller based on particle swarm optimization (PSO-MFFLC) for the nonlinear active suspension systems. The proposed method comprises the model-free based intelligent PID controller, the fuzzy logic controller, the time-delay estimation, and the particle swarm optimization. The advantage of PSO-MFFLC is quite simple structure and easy to be regulated. To validate the proposed controller, the nonlinear active suspension systems with non-linearity such as the parameters variation, external disturbance, and friction force effect are simultaneously taking into account to provide a realistic framework. The control objective is to deal with the classical conflict between minimizing vertical chassis acceleration to increase the ride comfort and keeping the dynamic wheel load small in order to ensure the ride safety. Moreover, modeling performed using a virtual detailed simulation environment LMS-AMESim, while the control part configured on Matlab/Simulink. Finally, the comparison of PSO-MFFLC with a classical PID, intelligent PID and the time-delay estimation control (TDEC) is conducted for different roads disturbances.

Energy Modelling and Indoor Air Quality Analysis of Cooling Systems for Buildings in Hot Climates

Energy consumption due to cooling and ventilation of buildings has grown significantly within the last two decades, and therefore advancement in cooling technologies has become imperative to maximise energy savings. This work numerically investigates the performance of vapour-compression unitary and centralised cooling systems for high rise buildings using an office case-study in the United Arab Emirates (UAE). Energy modelling, thermal comfort and indoor air quality analyses have been carried out using the Integrated Environmental Simulation Virtual Environment (IES-VE). Using the benchmark system based on fan-coil units, the findings have indicated that attaching a Variable Speed Drive (VSD) fan can reduce the overall energy consumption of the building by 8%, with 20% reduction in the cooling loads. The unitary cooling system operating on variable refrigerant flow principle achieved an energy reduction of approximately 30%; however, this system is not recommended in high-rise buildings as the CO2 concentration obtained is in excess of 3000 ppm, which is considerably higher than ASHRAE standards. It is essential for buildings running in hot climates to incorporate hybrid cooling techniques to relieve the load on conventional active cooling systems.

Urban Walkability Design Using Virtual Population Simulation

AbstractWe present a system to generate a procedural environment that produces a desired crowd behaviour. Instead of altering the behavioural parameters of the crowd itself, we automatically alter the environment to yield such desired crowd behaviour. This novel inverse approach is useful both to crowd simulation in virtual environments and to urban crowd planning applications. Our approach tightly integrates and extends a space discretization crowd simulator with inverse procedural modelling. We extend crowd simulation by goal exploration (i.e. agents are initially unaware of the goal locations), variable‐appealing sign usage and several acceleration schemes. We use Markov chain Monte Carlo to quickly explore the solution space and yield interactive design. We have applied our method to a variety of virtual and real‐world locations, yielding one order of magnitude faster crowd simulation performance over related methods and several fold improvement of crowd indicators.

Force-balancing algorithm to remove the discontinuity in soil force during wheel loader excavation

An important issue in developing a virtual simulation environment for a wheel loader is capturing the interaction force between the bucket and soil during excavation. In this work, we review several important studies on fundamental earthmoving equations (FEE) and confirm that discontinuity of soil force occurs when soil is loaded with a large terrain angle using a soil model based on traditional FEE for a wheel loader. This discontinuity is removed by recalculating the external friction angle to satisfy the force equilibrium condition under the assumption that the combined net normal and frictional force is zero in a certain condition. Comparison of an actual test with an inverse dynamic simulation using measured data confirms that the soil model proposed in this study is sufficient for estimating the external force transferred to the structure during actual operation. This soil force model can be used for durability and performance assessments in the initial design of wheel loaders.

Height Simulation in a Virtual Reality CAVE System: Validity of Fear Responses and Effects of an Immersion Manipulation.

Acrophobia is characterized by intense fear in height situations. Virtual reality (VR) can be used to trigger such phobic fear, and VR exposure therapy (VRET) has proven effective for treatment of phobias, although it remains important to further elucidate factors that modulate and mediate the fear responses triggered in VR. The present study assessed verbal and behavioral fear responses triggered by a height simulation in a 5-sided cave automatic virtual environment (CAVE) with visual and acoustic simulation and further investigated how fear responses are modulated by immersion, i.e., an additional wind simulation, and presence, i.e., the feeling to be present in the VE. Results revealed a high validity for the CAVE and VE in provoking height related self-reported fear and avoidance behavior in accordance with a trait measure of acrophobic fear. Increasing immersion significantly increased fear responses in high height anxious (HHA) participants, but did not affect presence. Nevertheless, presence was found to be an important predictor of fear responses. We conclude that a CAVE system can be used to elicit valid fear responses, which might be further enhanced by immersion manipulations independent from presence. These results may help to improve VRET efficacy and its transfer to real situations.

Evolving Behaviors for an Interactive Cube-Based Artifact

In the present paper we explore the idea of combining computation power and the availability of ordinary art spectators in order to produce new interactive art works. This is investigated for a particular application, which consists of producing new behaviors for a programmable art apparatus named C3 Cubes. Given the nature of the problem and some difficult challenges to be dealt with, an Interactive Evolutionary Computation (IEC) approach was devised. Furthermore, it was necessary to adopt a surrogate function method for approximating the user's preferences and to implement a Web-based virtual simulation environment for speeding up the generation and the evaluation of C3 Cubes projects. The integration of all these elements is crucial for producing new user-guided cube projects with interesting behaviors. The main approaches experimented in this research and the proposed design solutions are useful to solving similar problems in other domain areas, for example, in the context of game design.

Simulation software and virtual environments for acceleration of agricultural robotics: Features highlights and performance comparison

Research efforts for development of agricultural robots that can effectively perform tedious field tasks have grown significantly in the past decade. Agricultural robots are complex systems that require interdisciplinary collaborations between different research groups for effective task delivery in unstructured crops and plants environments. With the exception of milking robots, the extensive research works that have been carried out in the past two decades for adaptation of robotics in agriculture have not yielded a commercial product to date. To accelerate this pace, simulation approach and evaluation methods in virtual environments can provide an affordable and reliable framework for experimenting with different sensing and acting mechanisms in order to verify the performance functionality of the robot in dynamic scenarios. This paper reviews several professional simulators and custom-built virtual environments that have been used for agricultural robotic applications. The key features and performance efficiency of three selected simulators were also compared. A simulation case study was demonstrated to highlight some of the powerful functionalities of the Virtual Robot Experimentation Platform. Details of the objects and scenes were presented as the proof-of-concept for using a completely simulated robotic platform and sensing systems in a virtual citrus orchard. It was shown that the simulated workspace can provide a configurable and modular prototype robotic system that is capable of adapting to several field conditions and tasks through easy testing and debugging of control algorithms with zero damage risk to the real robot and to the actual equipment. This review suggests that an open-source software platform for agricultural robotics will significantly accelerate effective collaborations between different research groups for sharing existing workspaces, algorithms, and reusing the materials. Keywords: agricultural robotics, precision agriculture, virtual orchards, digital agriculture, simulation software, multi-robots DOI: 10.25165/j.ijabe.20181104.4032 Citation: Shamshiri R R, Hameed I A, Pitonakova L, Weltzien C, Balasundram S K, Yule I J, et al. Simulation software and virtual environments for acceleration of agricultural robotics: Features highlights and performance comparison. Int J Agric & Biol Eng, 2018; 11(4): 15–31.

A semi-automatic approach to implement rapid non-immersive virtual maintenance simulation

PurposeCurrent virtual simulation platforms provide various tools to generate non-immersive simulation processes purposefully in different domains. The generated simulation processes are adopted for analysis, presentation, demonstration and verification. In the virtual maintenance domain, this intuitive and visual method has benefitted product maintainability design and improvement. Generating an ideal and reasonable non-immersive virtual maintenance simulation is always time-consuming because of the complicated human operations and logical relationships involved. This study aims to propose a semiautomatic approach to increase efficiency in non-immersive virtual maintenance simulation implementation.Design/methodology/approachThe methodology analyzes the general catalogs of common maintenance tasks and explores the corresponding secondary development approaches of simulation tools that can achieve motion simulation in virtual environments, by focusing on the diversity, complexity and uncertainty in non-immersive virtual simulation process generation. Afterward, a single virtual human motion can be generated by controlling the parameters and indices of the simulation tools. Subsequently, all of the generated single motions are connected logically to simulate the entire maintenance process.FindingsInstead of selecting various tools, such as that in a traditional method, the proposed methodology analyzes and integrates the necessary basic parameters considering the characteristics of virtual maintenance simulation for a target maintenance activity.Originality/valueThe user can control the predefined parameters to generate the simulation combining several other simple operations in virtual environments. Consequently, the methodology decreases simulation tool selection and logic consideration and increases efficiency to a certain extent in non-immersive virtual maintenance simulation generation.

Three-dimensional Forest growth simulation in virtual geographic environments

Virtual geographic environments related to dynamic processes contribute to a human understanding of the real world. The results of growth simulations provide good estimations of the future status of forests, but they are typically expressed in plain text summaries, tables or static displays, making it difficult to analyse, understand and further apply the forecast data. The objectives of this study were to propose a strategy for integrating a three-dimensional (3D) geographic environment with growth models and to develop a 3D stand visualization software prototype. Forest growth increments were predicted using the growth models, whereas stand dynamics were simulated using detailed tree models to recognize the changes in the branch whorls and height of individual trees. The spatial structure of the stand was represented by linking each tree diameter class to a spatial distribution according to the features of a Voronoi diagram. The stand visualization system VisForest, which allows users to predict increments in the diameter and height of trees, was extended to estimate the number of trees in each diameter class and to visualize many aspects of a forest stand, e.g., individual tree structure, stem diameter at breast height (DBH, i.e., 1.3 m) distribution and height. The software system provides a specialized, intuitive tool for the visualization of a stand, thus facilitating the participation of various stakeholders in management and education.

Augmented reality in the business world

In the last issue of Business Information Review, we explored the emerging role of virtual reality (VR) technology in the workplace. VR, augmented reality (AR) and mixed reality (MR) describe a suite of closely related technologies, each of which attempts in some way to break down the distinction between the virtual and the real. Unlike VR, however, AR and MR do not place the user in the simulated virtual environment, but attempt to blend the elements of the virtual and the real. In this edition of Out-of-the-Box we look at the development of AR.

Effect of selected factors on stiffness of dowel joints

Furniture must be designed to suit the intended use. Producers need to guarantee its quality and stiffness. During external loading, there are internal forces that can be transmitted and may result in a failure. This article examines the dowel joint, which is one of the most popular furniture joints. It discusses the effects of selected parameters, such as type of loading (tension and pressure), the size of the dowel (one-half or one-third of the joined parts), wood species [beech (Fagus sylvatica L.) and spruce (Picea abies L.)], and the adhesives type (polyvinyl acetate and polyurethane), on the joint stiffness. The effect of the annual rings was also monitored; however it was not determined as significant. Based on the results, the dowel joint is recommended with greater diameters and while using PVAc gluing. Article also deals with test simulation in virtual environment using the programme Solidworks.

A Fire Drill Training System Based on VR and Kinect Somatosensory Technologies

The traditional fire drill is difficult, high cost, poor effect etc. in variety of fire scene simulation; a new fire drill platform combined Somatosensory camera Kinect and VR can achieve self-construction and virtual simulation fire drill based on somatosensory interaction; the platform achieves interaction between human and the 3D objects in virtual simulation environment, 3D modeling, scene building with Unity, identified human skeletal by Kinect, and using Euclidean distance matching recognition algorithm for body movements, and finally realizes the evaluation of fire drills.; the platform shows that the system has important practical significance and use value in fire drills, fire safety teaching and other aspects.

Understanding the Effect of Handedness on Both-Handed Task Performance: An Experimental Study based on a Haptic-Controlled, Simulation-Based Surgical Skill Training Scenario

ABSTRACTUnderstanding the performance on both-handed tasks, such as endoscopic surgery, is critical to better organize and develop appropriate instructional systems to improve the necessary skills of surgeons. However, in the literature, only a limited number of studies have investigated the effect of handedness on both-handed task performance. This study aimed to provide an understanding of the participants’ performance differences while performing both-handed tasks through a haptic user interface in a simulated virtual environment specifically developed for surgical training purposes. Twenty-four surgeons attending a medical school in Turkey voluntarily participated in the study. The duration, accuracy, and collision measures were automatically recorded by software. The results revealed that the left-handed participants performed the both-handed tasks (camera: nondominant hand, tool: dominant-hand) in a significantly shorter time than the right-handed participants. This study also showed that haptic-controlled simulation-based surgical skill training systems can potentially provide measures for better understanding the individual behaviors and deliver alternative training environments specific to individual requirements.