Real-time Virtual Simulation Research Articles

Real-Time Embedded Simulation Platform for Hippocampal Traveling Waves of Electric Field Conduction

The investigation of hippocampal traveling waves has gained significant importance in comprehending and treating neural disorders such as epilepsy, as well as unraveling the neural mechanisms underlying memory and cognition. Recently, it has been discovered through both in vivo and in vitro experiments that hippocampal traveling waves are typically characterized by the coexistence of fast and slow waves. However, electrophysiological experiments face limitations in terms of cost, reproducibility, and ethical considerations, which hinder the exploration of the mechanisms behind these traveling waves. Model-based real-time virtual simulations can serve as a reliable alternative to pre-experiments on hippocampal preparations. In this paper, we propose a real-time simulation method for traveling waves of electric field conduction on a 2D plane by implementing a hippocampal network model on a multi-core parallel embedded computing platform (MPEP). A numerical model, reproducing both NMDA-dependent fast waves and Ca-dependent slow waves, is optimized for deployment on this platform. A multi-core parallel scheduling policy is employed to address the conflict between model complexity and limited physical resources. With the support of a graphical user interface (GUI), users can rapidly construct large-scale models and monitor the progress of real simulations. Experimental results using MPEP with four computing boards and one routing board demonstrate that a hippocampal network with a 200 × 16 pyramidal neuron array can execute real-time generation of both fast and slow traveling waves with total power consumption below 500 mW. This study presents a real-time virtual simulation strategy as an efficient alternative to electrophysiological experiments for future research on hippocampal traveling waves.

An Optimal Simulation Configuration Method for Real-Time Simulation Based on Simulation Requirements

An optimal configuration method of simulation parameters, including the solver and step size of each sub-model, is proposed to realize real-time virtual simulation. The content of the presented study is threefold: firstly, the simulation requirements of three simulation modes, including Model-Exchange, Co-Simulation, and Hybrid Co-Simulation, are analyzed; secondly, the mathematical descriptions of the three simulation configuration problems are constructed, which are classified as an inequality problem and two assignment problems, where the assignment problems are decoupled; finally, an optimal simulation configuration procedure is proposed, where the analysis method and corresponding design methods for configured simulation parameters of each sub-model are given. The configuration method is applied to configure the simulation parameters of an aeroengine control system model with 6 separate components, and the simulation results verify the effectiveness of the proposed method. Specifically, the feasibility analysis results of the sub-models reveal that 4 of them meet the requirements while 2 of them are numerically unstable, which are consistent with the verification results. Meanwhile, after redesigning the infeasible sub-models using the proposed design methods, all the sub-models can meet their simulation requirements. In addition, an optimal configuration of the simulation parameters as well as several comparative configurations are provided, and the simulation results show that the time consumption of the optimal configuration is minimal and it can achieve real-time performance.

A Simulation Configuration Method for Real-Time Simulation Based on Requirements Analysis

A configuration method of simulation parameters, which include solver, step size, and solving precision, is proposed to realize real-time virtual simulation. The content of the presented study is twofold: firstly, simulation requirements are analyzed and a variant description of numerical stability using frequency and damping ratio is discussed; secondly, a simulation configuration procedure is proposed where an analysis method and corresponding guidance measures are given. The method is applied to configure the simulation parameters of an engine nozzle control system under 7 cases with different requirements and pre-configurations. Simulation results verify the effectiveness of the analysis method: 1 of them meets the requirements, 4 of them are time-out, and 2 of them are numerically unstable. Meanwhile, simulation results show that using the guidance measures proposed, all the infeasible cases can meet their simulation requirements after redesign by adjusting simulation requirements or designing the model, and achieve real-time performance.

Virtual simulation of otolith movement for the diagnosis and treatment of benign paroxysmal positional vertigo.

Benign paroxysmal positional vertigo (BPPV) is a clinical condition. The existing diagnostic methods cannot determine the specific location of otolith on the short or long brachial sides. Thus, visual and quantitative evaluation of the existing clinical standard diagnostic modality Dix-Hallpike test is needed to improve medical efficiency. Our goal was to develop a real-time virtual simulation system to assess a BPPV treatment manipulation. In this study, we used the proposed simulation system to observe otolith movement during a posterior semicircular canal BPPV diagnostic test, and to analyze the diagnostic mechanisms and strategies. Through visual cluster analysis of otolith position and analysis of otolith movement time in the standard Dix-Hallpike test, we can find that the positions of otoliths are relatively scattered, especially on the z-axis (z 1=10.67±3.98), and the fall time of otoliths at different positions has relatively large changes (t 1=22.21±1.40). But in the modified experiment z 2=4.93±0.32 and t 2=26.21±0.28. The experimental results show that the simulation system could track the state and the movement of otolith in real-time, which is of great significance for understanding the diagnostic mechanisms of BPPV evaluations and improving the diagnostic method.

A New Nonlinear Control Design Strategy for Fixed Wing Aircrafts Piloting

This paper proposes a novel nonlinear feedback control strategy for velocity and attitude control of fixed wing aircrafts. The key feature of the control design strategy is the introduction of a virtual control input in order to deal with the underactuation property of such vehicles and to indirectly control the orientation of the aircraft. As such, the proposed strategy consists of three control loops each realizing a specific task. Simulations are carried out by using the jetstream-3102 aircraft in a real-time virtual Simulation Platform for the development of Aircraft Control Systems (SP-ACS). The proposed approach of control is model-based for which we have introduces an identification part before test and validation. We use the Total Least Squares Estimation (TLSE) technique to identify the aerodynamic parameters, which are unknown, variable and classified. Each aerodynamic coefficient is defined as the mean of its numerical values. All other variations are considered as modeling uncertainties that will be compensated by the robustness of the piloting law. Simulation results on Jetstream-3102 aircraft show very good performance in terms of convergence towards the desired reference trajectories and in terms of robustness with respect to modeling uncertainties.

Research on the virtual reality technology of a pipeline welding robot

Purpose This paper aims to improve the scene sense of a virtual scene, the welding model of a virtual reality system of riser automatic equipment was constructed using Unity3D and UG software, which mainly included a welding car, welding guide rail, welding power supply, virtual camera and other equipment and the model was rendered. Design/methodology/approach The human-computer interaction page and simulation test of the system was produced using the user interface GUI system for creating a human-computer interaction scene. The operator could capture the welding status of the physical equipment accurately and in real-time so the virtual reality technology was very suitable for the remote monitoring operation integrated with the welding system. Findings Human-computer interaction design and collision detection were realized. In addition, the system simulation experiment was accomplished. With the continuous improvement and development of virtual reality technology real-time virtual simulation and monitoring, technology will become the main development trend. Research limitations/implications Based on virtual reality, the monitoring system can capture the operation status of physical welding equipment in real-time and accurately, which is very suitable for remote monitoring operation integrated with the welding system and also conducive to improving the monitoring level of the welding process. Practical implications This technology is time-saving and money-saving, for the operators do not have to be in a real welding environment and therefore they can get away from dangerous places. Consequently, it can avoid unnecessary injuries and problems. Social implications This technology can replace people to enter the dangerous and extreme environment to carry out welding operation, so it becomes the most effective means of nuclear power plant maintenance, space structure construction and marine engineering construction. In addition, it is time-saving and money-saving. Originality/value With the rapid development of virtual reality technology in recent years, it is a new research direction to apply virtual reality technology to the remote welding operation. This technology is different from the traditional way of welding for the operators can stay away from the welding scene especially some dangerous places.

Combining Homogeneous High Order Sliding Mode and Nonlinear Dynamic Inversion for fixed wing aircraft attitude and speed control

Abstract This paper addresses the problem of robust flight control for fixed wing aircrafts. Such systems are generally of Multi-Input Multi-Output (MIMO) form, tightly coupled and highly nonlinear whereby the nonlinearity resides both in the dynamic equations and in the aerodynamic coefficients. Consequently, we propose to combine Homogeneous High Order Sliding Mode (HHOSM) and Nonlinear Dynamic Inversion (NDI) approaches in order to deal with the piloting controller. The overall controller is designed so as to ensure the tracking of desired longitudinal velocity and attitude angles. The dynamics inversion uses nonlinear full-state feedback to globally linearize the dynamics of the selected controlled variables so that a linear controller can then be applied to regulate these variables with a desirable closed-loop behavior. To handle the nonlinearity, the desired closed-loop dynamics are given by an HHOSM controller. Simulations are carried out on a real-time virtual simulation platform for the development of Aircraft Control Systems (ACS). The obtained results demonstrate the effectiveness of the proposed controller. It is shown that HHOSM-NDI autopilot delivers a high dynamic tracking performance and can alleviate the chattering effect. Moreover, finite time convergence to the origin is ensured.

A virtual reality simulation for coordination and interaction based on dynamics calculation

ABSTRACTVirtual reality (VR)-based training system can provide experience for the decision-makers and inexperienced workers. We propose a novel solution for real-time hydrodynamic calculation between lifting bodies and liquids. This paper presents a brief description of the features and germane designed work of this system. The proposed system uses a type of distributed simulation frame and a real-time virtual simulation method based on dynamics calculation to support collaborative operation among several different types of workers and human-computer interaction (HCI). By applying efficient data transmission technology as well as the coordinate transformation method, it gets a wonderful balance between simulation precision and calculation efficiency for using off-line data. In the last, this study implements a real-time semi-physical simulation system that can simulate offshore lifting and installation. The applicability and accuracy of the proposed virtual simulation method have also been verified by conducting a case study.

Virtual Simulation and Remote Desktop Interface for CNC Milling Operation

Advanced development of computer network through Internet brings the technology to Manufacturing. Increasing the demand for effectively use of the production facility requires the tools for sharing the manufacturing facility by remote operation of the machining process. This paper introduces the methodology of machining technology for direct remote operation of networked milling machine. The tools including virtual simulation using CAD model, remote desktop protocol and Setup Free Attachment for remote operation of milling process are proposed. Accessing and monitoring of machining operation is performed by remote desktop interface and 3D virtual simulations. Capability of remote operation is supported by an auto setup attachment with a reconfigurable pin type setup free technology installed on the table of CNC milling machine to perform unattended machining process. The system is designed using a computer server and connected to a PC based controlled CNC machine for real time monitoring. A client will access the server through internet communication and virtually simulate the machine activity. The result has been presented that combination between real time virtual simulation and remote desktop tool is enabling to operate all machine tool functions and as well as workpiece setup.

Virtual Reality and Programming by Demonstration: Teaching a Robot to Grasp a Dynamic Object by the Generalization of Human Demonstrations

Humans possess the ability to perform complex manipulations without the need to consciously perceive detailed motion plans. When a large number of trials and tests are required for techniques such as learning by imitation and programming by demonstration, the virtual reality approach provides an effective method. Indeed, virtual environments can be built economically and quickly, and can be automatically reinitialized. In the fields of robotics and virtual reality, this has now become commonplace. Rather than imitating human actions, our focus is to develop an intuitive and interactive method based on user demonstrations to create humanlike, autonomous behavior for a virtual character or robot. Initially, a virtual character is built via real-time virtual simulation in which the user demonstrates the task by controlling the virtual agent. The necessary data (position, speed, etc.) to accomplish the task are acquired in a Cartesian space during the demonstration session. These data are then generalized off-line by using a neural network with a back-propagation algorithm. The objective is to model a function that represents the studied task, and by so doing, to adapt the agent to deal with new cases. In this study, the virtual agent is a 6-DOF arm manipulator, Kuka Kr6, and the task is to grasp a ball thrown into its workspace. Our approach is to find a minimum number of necessary demonstrations while maintaining adequate task efficiency. Moreover, the relationship between the number of dimensions of the estimated function and the number of human trials is studied, depending on the evolution of the learning system.

Real-Time Design Patterns in Virtual Simulations

In a virtual simulation, people and real system hardware interact with the simulated system. Introducing these real-world elements into the simulation environment imposes timing constraints which, from a software standpoint, places the design into the class of real-time systems. We develop two software design patterns for real-time virtual simulations: a variant of the model-view-controller architecture and a companion component pattern that facilitates the development of hierarchical simulation models, graphical displays, and network input/output (I/O ) that meet real-time constraints. These design patterns promote good programming practice and allow the performance of a design to be evaluated using rate mono-tonic analysis techniques.We also introduce selective abstraction and focused fidelity to reduce simulation development time and cost, while simultaneously improving runtime performance and the validity of simulation results.