Applied Mechanics and Materials Vol. 902

Abstract: The main propulsion plant (MPP) on marine sea-going ships consisting of a diesel engine as the main engine and driving the ship propeller is with the torsional vibrations to be calculated in accordance with the Rules for the Classification and Construction of Sea-Going Ships. The Rules are given by one of maritime registers in the world that are the members of IACS, such as Russian Maritime Register of Shipping (RMR), DNV, ABS, at el. The TV calculation (TVC) on the MPP usually is certainly a monumental calculation task and is conducted with special software for TVC. Nowadays, in accordance with the Rules, almost modern software products for TVC have the abilities to calculate the TVs at normal working regimes and at misfire regimes (called by Normal or Misfire regimes relatively) with only one of cylinders of marine diesel engine (MDE) while engine speed range covers from the minimum to maximum values of the operation speeds. The paper presents improved algorithms and software for automatic calculating the TVs (SATVC) at the Normal and the Misfire regimes, in which the misfiring processes appear not only in one cylinder, but also in two of the MDE cylinders together. The SATVC was based on the made mathematical models, algorithms and coded in LabView by authors. The SATVC consists of modules for automatic calculation of freedom TVs (FTVs), excited torsional moments (ETM), excited TVs (ETVs), permitted torsional pressures (PTP), and common management (CTVC). TVC at every working regime of MDE was automatically conducted in the following procedure: Configuration of the MPP for TVC; Calculation of FTVs; Calculation of ETM; Calculation of ETVs); Calculation of ETVs, and solution of the TVC in considered working regime. The working regime of MDE was modeled by a vector of firing coefficients (VFC) of every MDE cylinder.

Abstract: This paper presents the research of model-base design and control of Remotely Operated Vehicle (ROV) built in VietNam Automation & Mechatronics Laboratory (VIAMLAB). This is one of the most important types of underwater robots used in water environments for many purposes, especially for navy and marine industries. The design keeps our tethered ROV self-stabilized in the horizontal plane. It is also equipped with thrusters and sensor feedbacks, allowing 6 degrees-of-freedom motion. Moreover, cameras and grabber integrated into ROV support underwater survey tasks. In addition, the paper also simulates controllers with the main task of keeping depth for ROV. The controllers designed and surveyed here include: PID, optimal control (LQR), standard model control (MRAC) and combination controller between LQR and MRAC. The performance of the algorithm will be evaluated through simulation results using Matlab / Simulink.

Abstract: This paper presents modeling and simulation of spring-mass damper system for quarter car in the Simulink environment. The simulations in this research have been carried out by using the Simulink of Matlab. The parameters in the simulation model for the suspension system under study include car body mass, wheel mass, spring and damping elements of shock absorber, and tire. A road disturbance profile comprising a combination of two sinusoidal curves is modeled. Controllers that are used in this study are the proposed fuzzy logic controller. The purpose of this research is to improve vehicle comfort using the Fuzzy Logic Controller (FLC). The simulation results of the system perform well fulfill the minimum percentage requirements and fast stability time, provide good leveling of stability and ride comfort.

Abstract: Autonomous Guided Vehicles (AGV) have the ability to operate on their own, perform tasks without human intervention. However, the investment cost is very high, so it is not suitable for countries with cheap workers like Vietnam. Therefore, this article will aim to build a complete AGV model that can move to the given coordinates. Model of AGV is 6-wheeled vehicles driven by 4 engines with the advantage of good movement in soft terrain, subsidence, ruggedness, slope, easy to balance and limit the vibration. Furthermore, we propose a method to improve the quality of the traditional A* algorithm by eliminating unnecessary intermediate points, which is Shortcut Path Reduction (SPR). Experimental results show that the vehicle can perform the bending technique, following straight lines and broken lines. Besides, the SPR not only met the requirements but also reduced the length of the journey.

Abstract: Agriculture is one of the key sectors of Vietnam economy as well as most country in the world. Nowadays, the urgent requirement for it is an increase in production, quality of labor and labor productivity. Therefore, we researched and built self-propelled robot serving in agriculture. This promises to be one of the pioneer products with application of science and technology to modernize agriculture in our country. The robot is based on combining two main components: Automatic guided vehicle (AGV) and Delta robot with different specific tasks. Being an AGV, robot can locate and automatically move in the field without human intervention. Besides, the Delta robot is the main structure impacting directly on the field such as: watering, weeding, fertilizing, … depending on our need.This paper focuses on analyzing 3 major sections: the overall design of robot, control algorithms and computer vision programs. The System Overview helps readers have an overview of the shape and operation of robot. The control algorithm focuses on control algorithm analysis of Delta robot. And the last part introduces the computer vision programs used in Robot.The experimental results are evaluated objectively, so we can see both of the successes and the limitations. But in general, with the task set out in the subject: identifying and following vegetable rows in combination with identifying and moving the robot arm to the target need to be impacted, the robot has done very well and the results are within acceptable errors.

Abstract: This paper proposes a method of using the B-spline mathematical model to plan high smoothness curve trajectories with heading condition through given waypoints for autonomous underwater vehicles (AUVs) in particular and ships with rudder systems in general. In addition, this paper examines some of the physical limitations of this vehicle, which lead to some binding conditions of the trajectory. Besides, the paper applies B-spline approximation method to reduce the curvature of the trajectory, when waypoints are too close and we do not need to go through exactly these waypoints in the 2D plane. Finally, this paper also proposes the genetic algorithm application with some modifications to solve the optimization of B-spline path length with constraint in turning radius of the vehicle.

Abstract: Nowadays, 3D printing technology or Additive Manufacture (AM) is becoming more and more popular in industries and life. Additive Material technology is a technology of linking or crystallizing materials under the control of a computer to create three-dimensional details. Additive Manufacture Technology currently consists of many different methods, in which the method of extruding molten materials through the nozzle called Fused Deposition Modeling (FDM) is the most popular. Almost all 3D printer machines that use this method are now very popular in the market, with the ability to work suitable for many types of objects, from individual scale to company one. However, the design and manufacture of these machines are carried out according to traditional methods, with many limitations. The paper presents an application of selective design method for FDM technology analysis results according to the module in [5] to implement the control system design of FDM to reduce costs and improve the reliability of the product.

Abstract: Nowadays, 3D printing technology is the national theme in Vietnam. Most countries have national strategies in research and development and widely apply 3D design and printing to all industries, organizations and people. 3D printing technology has been applied in many industries such as automotive, aviation, health, construction, electronics ... Almost all Digital Light Processing (DLP) 3D printing machine on ​​domestic market are imported from Chinese, Korean manufacturers ... with medium quality but high cost. The paper presents a study of application of selected design methods and tools of engineering design process to design DLP 3D printer driver with lower cost but equivalent quality with the other machine in series on the market that are imported from China.

Abstract: 3D printer technology has been applied to a lot of industrial branches such as automobile, aircraft, medicine, civil engineering, electronic engineering. Normally in Vietnam, the plastic fiber, raw material that is the most popular application is hot plastic fiber extruding through FDM nozzle... is being imported from China, Korea, and Taiwan. The paper represents our own research on the application of the technical design processes for design a plastic-bamboo fiber extruder that is sustainable, environmental friendliness, consumes domestic raw material and saving national budget for importation and mastering the technology of extruding plastic bamboo fiber.