In laparoscopic surgeries, robotic systems commonly use trocar fixation to achieve remote center motion (RCM). However, this fixation occupies the surgeon's operational space and limits surgical flexibility. It is essential to ensure adequate workspace while maintaining RCM to enhance procedural efficiency and safety. This paper introduces a novel approach to preserve RCM without relying on trocar fixation. The proposed method integrates a six-degree-of-freedom robotic arm with a dual end-effector system, employing tool coordinate storage and remote center point definition to achieve precise four- degree-of-freedom RCM motion control. To validate this method, an experimental setup with an optical tracking system was utilized to measure and calibrate the remote center position. The results indicate that the robot maintained RCM with mean positional errors of 0.672, 0.318, and 0.704 mm along the x, y, and z axes, respectively, yielding a three-dimensional mean error of 1.136 mm. These findings demonstrate the effectiveness of the method in maintaining RCM while maximizing surgical workspace and operational flexibility.

As advanced driver-assistance systems become more common in commercial vehicles, there is a growing need for evaluating safety of vehicles. Low platform target robot systems play a crucial role in this evaluation process as they can assess safety performances of autonomous vehicles. Driving stability of a target robot during real vehicle tests depends significantly on its suspension system. Therefore, developing an appropriate suspension device for the target robot is of utmost importance. This study aimed to improve driving stability by comparing two different suspension configurations: a single rocker and a double rocker, both incorporating a crank rocker mechanism. Initially, a two-dimensional model that met constraints of the suspension device was developed, followed by an analysis of reaction forces. Subsequently, an optimal design was determined using design of experiments principles based on parameters of a 2D model. The manufactured suspension system model based on the optimal design underwent multi-body dynamics simulation to evaluate driving stability. Comparative analysis of driving stability for both configurations was performed using MBD simulation, offering insights into the superior suspension design for the target robot.

Environmental issues have become a global concern recently. Countries worldwide are making efforts for carbon neutrality. In the automotive industry, focus has shifted from internal combustion engine vehicle to eco-friendly vehicles such as Electric Vehicles (EVs), Hybrid Electric Vehicles (HEVs), and Fuel Cell Electric Vehicles (FCEVs). For driving strategy, research on vehicle driving method that can reduce vehicle energy consumption, called eco-driving, has been actively conducted recently. Conventional cruise mode driving control is not considered an optimal driving strategy for various driving environments. To maximize energy efficiency, this paper conducted research on eco-driving strategy for EVs-based on reinforcement learning. A longitudinal dynamics-based electric vehicle simulator was constructed using MATLAB Simulink with a road slope. Reinforcement learning algorithms, specifically Deep Deterministic Policy Gradient (DDPG) and Deep QNetwork (DQN), were applied to minimize energy consumption of EVs with a road slope. The simulator was trained to maximize rewards and derive an optimal speed profile. In this study, we compared learning results of DDPG and DQN algorithms and confirmed tendencies by parameters in each algorithm. The simulation showed that energy efficiency of EVs was improved compared to that of cruise mode driving.

In the current SI (International System of Units), the kilogram is defined by the mass of a material artefact. In this instance, because the artefact can be damaged during use, the present definition is inherently considered unstable. To overcome the shortcomings of the present kilogram definition, the SI will be redefined in near future. In the new SI, the kilogram will be redefined by fixing the numerical value of the Planck constant. After the kilogram redefinition, realization experiments which link the Planck constant to the mass will be necessary. In the new SI, the kilogram will be realized through experiments including the Kibble balance and the X-ray crystal density. The Kibble balance, which is named for the scientist Bryan P. Kibble, is an electromechanical device comparing mechanical power and electrical power. The electrical power is proportional to the Planck constant, because of the voltage and resistance are measured using the Josephson effect and the quantum Hall effect, respectively. The Planck constant is an invariant and not a characteristic of a man-made object, or a specific experiment. The new mass unit is more stable than the current one, and will pave the way for the advancement of precision measurement.

As geometry of machined parts becomes complex the demands for more precise and faster machining using advanced computerized numerical control (CNC) are increased. Especially, recently improved computing power of CNC enables the implementation of the complicated control algorithms. Consequently a variety of intelligent control algorithms have been studied and implemented in CNC. This paper reviews the recent progress of control technologies for precision machining using CNC in the area of interpolation, contour control and compensation. In terms of interpolation several corner blending methods and parametric curves are introduced and the characteristics of each method are discussed. Regarding contour control algorithms recently developed multi-axis contour control methods are reviewed. Latest research efforts in compensation algorithms for geometric, thermal and friction induced errors in CNC machining are introduced.

Bearings having a small clearance during normal operation are selected. In some cases, bearings having a negative clearance when mounted are selected, to generate internal stress which enables achieving various effects. This so-called preload can be applied only to rolling bearings and not sliding ones. The performance of bearings is greatly affected by the applied preload. Application of a heavy preload to enhance the stiffness at the spindle undermines the high-speed rotation performance. In contrast, when a light preload is applied for high speed rotation, the stiffness is undermined. Therefore, a variable preload method is required. This study aims to develop a variable preload device using a linear actuator of the ball screw type, and to perform the performance evaluation of the developed device. Our studies verified that the proposed device worked satisfactorily.

This paper describes the derivation methodology of the working torque predictive model that can be used in the initial design stages of the impact hammer tool. The working torque control mechanism is designed, taking into account various factors, such as the force of the spring and friction. Firstly, the analysis dynamic model for working environments was modeled as an additional bush and spring, and verified by comparing the test results of the working torque. Secondly, the main performance parameters of the working torque were theoretically defined by analyzing the operating mechanism. The equation to predict the working torque was derived using the dynamic analysis results according to the value changes of the parameters. The prediction equation of the working torque was validated by comparing the predicted results with the experimental data. The error difference between the experimental data and the predictive model results was found to be 8.62%.

In the recent field of Machining, with the improving efficiency of processing, the index table is a key unit according to the increase of parts in available processing when working with the three axes at the same time. As an essential product of MCT, the index tables effect an influence on product quality of machined parts. Therefore, it is necessary to design the shape of index table with stability, high stiffness, lightweight structure. In this study, the optimal shape of index table was proposed using by design of experiment. The maximum displacement and stress analysis were carried out by using FEM software. The optimized shape was verified by using the statistical software. The results of shape optimization were confirmed that both displacement and stress were reduced in comparison with initial model.

Recently, many researchers and industry are looking for ways to decrease the use of lubricants because of economical and environmental reasons. One of the lubrication technologies is the MQL method. This study presents a research of MQL and Wet milling processes of Al 6061 material. For this experiment, the test specimen is suggested, and various machining conditions are applied. And, shape of micro-pattern which has been recently spotlighted is included in the test specimen. In order to compare MQL with Wet machining, several milling experiments were carried out, varying feed rate, cutting speed, depth of cut, etc. Finally, the surface roughness results of machining tests according to the process conditions were measured. It is expected that the results of machining experiments can be used to predict the surface roughness of various MQL milling processes.

A spindle unit is very important in machine tools. It has a direct effect on machining accuracy. The static and dynamic characteristics of the spindle unit should be considered in the initial design stage for manufacturing of precision product. This study describes an investigation for deriving design stability of a 20,000rpm heavy-cutting spindle for precision machining. Static and dynamic characteristics of the spindle, such as deformation, stress, natural frequency and mode shapes are analyzed using finite element analysis. The 20,000rpm heavy-cutting spindle is confirmed that it is successfully designed through finite element analysis.

Recently, laser processing technologies have been developed in many different industrial fields. The laser processing technologies are widely being applied such as laser assisted machining, cladding, heat treatment and coating. In the laser modules of the laser assisted machining system, laser lens is very important for accuracy and productivity of product. As the laser beam size, shape and focusing distance change, heat input energy of preheating point can be changed, the laser module of the laser assisted machining system should be equipped with various lenses differing beam size, beam shape and focusing distance. In this study, the rotary and linear laser modules are suggested. The finite element analysis is carried out to certify the static and dynamic stabilities of the developed laser modules. Finally, the rotary and linear laser modules have been fabricated successfully using the analysis results.

Recently, in industry field, many researchers are looking for ways to reduce the use of lubricant because of environmental and economical reasons. MQL lubrication is one of many lubrication technologies. The aim of this study is to evaluate the machinability considering lubrication methods and taper angles of workpieces for turning of SCM440. Workpieces of two shapes such as workpiece with and without taper angle are used. And two lubrication methods such as MQL and Wet have been considered. And cutting force and surface roughness are used as characteristic values. Cutting speed, feed rate, injection angle and distance are used as design parameters. The characteristic values were statistically analyzed by Taguchi method. From the results, main effects plot and importance of each parameter according to conditions are analyzed. Finally, this study has been suggested the optimum machining conditions according to the lubrication methods, machining conditions and shape of workpiece.

Automatic tool changer(ATC) is typically provided to a machine tool to improve the efficiency of the machine tool significantly by saving time in moving, switching, installing and storing tools as well as adjusting a calibrating the machine tool. In this study, technical trend of machine tools automatic tool changer are analyzed by patent mapping. And future development direction of automatic tool changer has suggested. The analysis is carried out by using problem solution map for the applied patent during 2000 and 2010 in USA, Japan, Europe and Korea.

Laser assisted machining (LAM) is machining method that performs a machining for workpieces using laser beam preheating. LAM is in the early stage of its applications and has only been used in limited fields including turning, planning and micro end-milling throughout the world. LAM system should be able to move to the laser radiation direction and to rotate on a tool path for machining of complex shapes. A laser module with two-axis manipulator is designed in this study. It has been performed static structural analysis and shape modification of the manipulator. As the results of shape modification it has been obtained better results than the initial model. These results will be able to use in development of the two-axis manipulator.

Laser assisted machining is the processing method that preheating brittle materials by laser heat source and cutting the soften area. This processing applied to various industries because it can be cutting difficult-to-cut materials. However, the laser assisted machining appeared the limitations of processing for equipped with the spindle. So, it assumed separate model that spindle and laser assisted machining. In feed, the calculation of changing the angle of the laser module according to preheat point and the shape of the feed is important and it tried easy calculating changing angle of 1-axis Manipulator in separate model. In 3 types feed shape, angle of 1-axis Manipulator was calculated when fixed and moved in the outside of spindle. In this study, suggest 2 types of methods for laser module when fixed and moved.