Comprehensive Simulation System Research Articles

Design and Implementation of Autonomous Underwater Vehicle Simulation System Based on MOOS and Unreal Engine

An effective autonomous underwater vehicle (AUV) simulation system can greatly improve development efficiency and reduce the cost and risk of actual equipment operation. In this paper, a comprehensive simulation system is developed using Mission Oriented Operating Suite (MOOS) and Unreal Engine 4 (UE4). The former provides an open-source development framework and application components, which are widely used in the field of underwater robots. The latter is a well-known game development engine that has realistic effects and various plugins. As far as we know, there are few simulation systems based on MOOS and UE4. Moreover, a modular architecture for the simulation system is designed and implemented in the paper. The developed system consists of four subsystems, including the simulation editing and controlling subsystem, shore-based operation subsystem, simulation engine subsystem, and three-dimensional (3D) visualization subsystem. These subsystems have modular characteristics and independent functions and communicate with each other through network sockets. Through the system, users can customize simulation scenarios, send missions and control simulation progress from the graphic user interface. And the system can be used in operation training, software testing, algorithm verification of AUV, etc.

A fuzzy control method with the optimized intelligent weight function for directional control during aircraft autoland rollout

Aircraft landing rollout process is a complex and high non-linearity process. The mutual effects of tire dynamics, aerodynamics and multi-body dynamics should be taken into considerations. It is difficult to be accurately expressed in mathematics. Aiming at obtaining a good directional control capability during aircraft autoland rollout, a comprehensive simulation system was constructed including all those three aspects above, and a fuzzy control method with intelligent weight function was adopted which is appropriate for systems difficult to be modeled exactly. In the paper’s work, the intelligent weight function was optimized by the power function for the first time. By adjusting the exponential k, the fuzzy control rules can be conveniently and reasonably optimized. Through a set of simulations without crosswind, the optimal k was obtained. Finally, the simulation tests under conditions of 20 kn crosswind with ±5° original drift angles were conducted with the system configured by the optimal k. Accroding to the results, the optimized fuzzy controller can give a good directional control performance.

Development of the Comprehensive Simulation System for Autonomous Ships

In recent years, there has been a growing interest in autonomous ships, and efforts to realize autonomous ships are underway in Japan. Automated and unmanned ships are expected to improve safety by reducing accidents caused by human with the supports by the automated system. On the other hand, it is necessary to demonstrate that the autonomous ships are safely operated to implement the autonomous ships in society. The National Maritime Research Institute (NMRI) has been studying the evaluation method of safety of the autonomous ships and developing a simulation system as a tool for the evaluation. This paper introduces a comprehensive simulation system including a ship handling simulator, and the evaluation method using the simulation system.

Housing Price Research Based on System Dynamics Model

Based on the theory of system dynamics, a system dynamics model regarding to housing price is constructed. The changes on housing price are simulated via Vensim DSS software, and the effectiveness of the model is verified. Policy regulation experiments are conducted from the prospective of population, land and taxation that are mostly concerned by the government. It can be concluded that the land policy and taxation policy are the main methods for regulation. It provides macro-direction for the government to manage the commercial housing market and control the price of commercial residential house, as well as corresponding decision basis for house purchasers and commercial housing developers in their purchasing and investing. It also provides a systematic prediction method for the comprehensive simulation system of the commercial housing market.

Registration of mandibular movement for dental diagnosis, planning and treatment

During the last decade, due to the digitalization of many procedures in the dental workflow, dentistry has undergone many changes. To begin with, virtual articulators substituted traditional mechanical articulators. Thanks to virtual articulators, exploring more options (manufacture in clinic, laboratory in different materials, among others) for each case became possible. Now, this study proposes a step forward in the registration of the patients’ mandibular movements, which allows taking into account the kinematics of each patient’s mandible in the design of prostheses. Surgeons and dentists require a comprehensive simulation system of the mandibular movements as a support for their design work. Taking into consideration the market needs, this article describes the work carried out to develop a method to capture mandibular movement. Using a Leap Motion device and rapid prototyped pieces, the developed system is simple and economically affordable. To design a dental prosthesis taking into account the movements of the antagonist, the most significant information regarding these mandibular movements—lateral movements, retrusion, protrusion and chewing—is necessary. In order to minimize interventions at the clinic, this kinematic design is essential because it eliminates occlusal interferences. However, this registration system is only applicable when an intraoral scanner and a virtual face bow are already integrated. Since the maxillary and mandibular casts must simulate the registered movements, the origin and relative position between both casts is essential. This virtual location of models and simulation of these movements enables the dentist, surgeon and lab technician to achieve a more interactive design, thus leading to a more functional design.

Multiple-level Digital Loudspeaker Array

In modern audio systems, the signal path is generally digital in nature, with the notable exception being the analogue loudspeaker. Digital Loudspeaker Arrays (DLA) have been proposed as an alternative approach. Generally, they have a relatively poor acoustic output, as high audio quality requires an impractically large number of speaklets (tiny loudspeakers). We address this limitation by proposing an increase in the number of quantizing levels, thus requiring fewer speaklets. A comprehensive system simulation has demonstrated the feasibility of such a system to produce high quality sound, with a hardware implementation currently being investigated.

Multibody simulation of a generalized predictive controller for tiltrotor active aeroelastic control

A generalized predictive control has been developed for the control of the aeroelasticity and structural dynamics of a tiltrotor. Adaptivity is the key feature of the proposed technique. It gives the controller the capability to autonomously follow the variations of the system. A comprehensive simulation system has been adopted to design and test the adaptive regulator under realistic conditions. The aeroservoelastic tiltrotor has been modelled using a multibody approach, considering the structural dynamics, the aerodynamics, the blade pitch control system kinematics, and actuator and sensor dynamics. Numerical simulations illustrate the capability of the adaptive controller to reduce wing vibrations and loads while significantly extending the flutter-free flight envelope. This controller shows satisfactory performances within the whole flight envelope as it is able to properly work in different rotor trim conditions and varying structural properties in the presence of external disturbances and measurement noise.

A Comprehensive Mechatronic Modeling and Simulation of Electric Power Steering System

Electric power steering (EPS) systems are rapidly replacing existing traditional hydraulic power steering systems due to their important advantages such as fuel and cost savings, environmental compatibility and flexibility. Many articles are available in this field in which EPS is viewed only from one specific aspect. Other aspects have been introduced only by brief equations neglecting some main details regarding the important effects of ignored parts. Therefore, it is quite necessary to make a complete analysis of every part of this system with a right combination between them. It makes a comprehensive simulation system for EPS. This matter needs sufficient knowledge in mechanical, electrical and control sciences and how to assemble them with each other properly. Therefore, Mechatronic is the most appropriate branch of science to achieve this goal. In this paper, a complete model of EPS is presented which includes a 7-D.O.F mechanical model of steering system. A Permanent Magnet Synchronous Machine (PMSM) is used to supply the assist torque to steering column. Vector Control Method is utilized for controlling the motor. A PID controller determines the reference assist torque value. The results are presented to estimate the model precision and evaluation of model.

System topologies and performance evaluation of the RESOLUTION embedded local positioning system

This article introduces a hybrid communications and positioning system, developed in the course of the EU-endorsed RESOLUTION project. The system provides a reconfigurable, embedded hardware platform fit to support a variety of deployment scenarios. The flexibility of our solution is assessed by means of a comprehensive system simulation.

Evaluation of Satellite-Based Navigation Services in Complex Urban Environments Using a Three-Dimensional GIS

We developed a comprehensive simulation system for evaluating satellite-based navigation services in highly built-up areas; the system can accommodate Global Positioning System (GPS) multipath effects, as well as line-of-sight (LOS) and dilution of position (DOP) issues. For a more realistic simulation covering multipath and diffracted signal propagations, a 3D-ray tracing method was combined with a satellite orbit model and three-dimensional (3D) geographic information system (GIS) model. An accuracy estimation model based on a 3D position determination algorithm with a theoretical delay-locked loop (DLL) correlation computation could measure the extent to which multipath mitigation improved positioning accuracy in highly built-up areas. This system could even capture the multipath effect from an invisible satellite, one of the greatest factors in accuracy deterioration in highly built-up areas. Further, the simulation results of satellite visibility, DOP, and multipath occurrence were mapped to show the spatial distribution of GPS availability. By using object-oriented programming, our simulation system can be extended to other global navigation satellite systems (GNSSs) simply by adding the orbital information of the corresponding GNSS satellites. We demonstrated the applicability of our simulation system in an experimental simulation for Shinjuku, an area of Tokyo filled with skyscrapers.

Geometrical Modelling of a Ball-End Finish Milling Process for a Surface Finish

Finish milling with a ball-end mill is a key process in manufacturing high-precision and complex workpieces such as dies and moulds. Due to the complexity of the milling process, it is difficult to observe experimentally the surface microcharacteristics such as the surface topography and roughness of machined workpieces real-time during machining. This necessitates simulation of the process. In this area, the existing related simulation researches focus mainly on scallop heights; few have presented a whole picture of the microcharacteristics of milled surfaces. A comprehensive simulation system has been developed for predicting the surface topographic features and roughness formed in the milling process, and the effect of machining parameters was studied. This paper focuses on the modelling method and theory adopted in the simulation system. The method to improve the calculation accuracy is discussed in detail. The approach to incorporate the effects of the cutting tool run-out and wear is also presented. Experiments are also carried out to verify the simulation results.

A Geometrical Simulation System of Ball End Finish Milling Process and Its Application for the Prediction of Surface Micro Features

Finish milling with a ball end mill is a key process in manufacturing high-precision and complex workpieces, such as dies and molds. Because of the complexity of the milling process, it is difficult to evaluate the microcharacteristics of machined surfaces real time, which necessitates the simulation of the process. In this area, the existing related simulation researches mainly focus on scallop height evaluation, but few have presented a whole picture of the microcharacteristics of milled surfaces. This paper develops a comprehensive simulation system based on a Z-map model for predicting surface topographic features and roughness formed in the finish milling process and studies the effect of machining parameters. The adoption of the discretization concept of the tool’s cutting motion makes it possible to dynamically track the cutting tool-workpiece interaction with the tool movement and to describe the cutting edges-workpiece discrete cutting interaction more realistically and, therefore, the microcharacteristics of the machined surfaces more accurately. Also, the effects of the cutting tool run-out and wear are incorporated into the developed model through modifying the tool center motion and the cutting-edge shape, respectively. As a fundamental study, the tool-swept envelope has been simulated. The developed simulation system is applied to thoroughly study the surface features formed by the 2.5-axis finish milling process. The application for general three-axis machining is discussed. Additionally, this paper studies the effect of the tool inclination, which is the most common characteristic in 3+2- or five-axis milling processes, on the machined surface features. Experiments are carried out to study the milling process and to verify the simulation results. The difference between the simulated and experimental results is discussed, and the reason behind the difference is explored.

Comprehensive Simulation System for Advanced Bus Priority Schemes by tiss-NET

The purpose of this study is to build the simulation system which can evaluate bus priority schemes comprehensively. First, authors improved tiss-NET which is micro traffic simulation system, tocorrespond to actually bus run which based on timetable, detailed demand model of bus passenger. Second, autors add function of several bus priority schemes, bus lanes, bus priority signal system and scheme of reduce bus stop time to tiss-NET. Then, using tiss-NET, we analysis that effect of these bus priority schemes and combination ofthese schemes by estimating trip time of bus and passenger.

Comprehensive Simulation System for Bus Priority Schemes by tiss-NET

The purpose of this study is to build the simulation model of tiss-NET which include car behavior of bus stop and bus bay. At first, authors verified the bus stop and bus bay model to compare to result of survey, and estimated that effect of construction bus bay and scheme of reduce bus stop time. Result of analysis, those schemes were effective for reducing trip time. Then, in these simulation, the situation that interval of two or more buses becomes too close and/or too far, which often occur in congested bus routes, could also be reproduced.

Impact of dynamic decision making on hub‐and‐spoke freight transportationnetworks

Hub‐and‐spoke freight transportation networks use consolidation as a means to achieve the economies of scale. The operations and rules in such networks are very complex. This paper considers the tactical planning for these networks and the study is driven by the emerging new information technology that allows us to use real‐time information to guide decision making. First, we develop a comprehensive simulation system that can capture the relationships between the network configuration, load planning, complicated work rules, trailer-closing policies, day of the week effects, and service commitment. Through the simulation study, we highlight the effects on costs and services if we add the time dimension in the tactical planning and if we change some parameters that govern the trailer closing process. The simulation results suggest that if we can dynamically change the shipment routes and the trailer‐closing rules, the service levels can be improved substantially. Based on the results, we further formulate the trailer‐closing policy as a dynamic programming model. We consider a framework for developing solution methods and discuss issues and possible research directions under this framework.