In this paper, we developed a virtual model predicting the tool deflection induced surface error and investigated the sensitivity and direction of the maximum surface error in various tool geometries and cutting conditions. The characteristics of the error were classified into the axial sensitive, radial sensitive, robust, overcut, and overlap zones according to the depth of cut. The maximum surface error was sensitive to the uncertainty of the radial depth of cut and robust to axial depth variation at the finishing process using a small radial depth of cut. The radial sensitivity was reduced by a large helix angle of tool. The sensitivity was decreased by increasing the depth of cut and it arrived at zero in the robust zone where the maximum surface error was not changed by both radial and axial depths of cut. An overcut occurred if axial and radial depths were deep and the overcut zone was enlarged by the helix angle and the number of teeth.
A theoretical and numerical FSI approach is used to predict the mass flow in a Coriolis flow meter. By comparing with the experimental results according to the relationship between mass flow and the time phase difference at the inlet and outlet of the tubes, the authors could determine the reliability of the present results from a theoretical and numerical approach in this paper. The mass flow has a linear relationship with the time phase difference, which is a unique parameter to measure true mass flow; therefore, for more precise measurement, it should be long enough to detect the signal within the given time resolution afforded by the detecting system and control system. Compact size and manufacturability, which are the important factors that decide the product competitiveness, should also be considered. In this paper, inversed triangle shaped and conventional U shaped Coriolis flow meters are designed, their time phase difference performances are predicted, and the results from experiments are well matched with the predicted results from the above-mentioned analysis.
Herein, we describe the development of a wearable lower limb rehabilitation robot that can perform walking movement according to the walking pattern trajectory. The robot can adjust the left and right widths of the waist and the front and rear widths of 100 and 20 mm, and the length of the thigh link and calf link by 100 and 80 mm, respectively, so that stroke patients of different heights and weights can use it in hospitals. For manufacturing the lower limb rehabilitation robot, the right exoskeleton was safely designed through structural analysis, and the motor and reducer constituting the hip joint actuator were calculated. The fabricated lower limb rehabilitation robot was divided into its own characteristic experiment and wearing characteristic experiment. Its own characteristic experiment was an experiment by the robot itself, and the wearing characteristic experiment was an experiment conducted after a person wears the robot. Through these two experiments, angular deviation of the walking pattern was analyzed. Results of the analysis confirmed that the wearable walking characteristic test was performed within 3.1° based on the self walking characteristic test result. Therefore, the fabricated lower limb rehabilitation robot can be used for gait training in stroke patients.
In this paper, we propose a method to generate the trajectory of a robotic shoe sole spray system by extracting target points from a 3-D model of a mold sole. Point cloud transformation based on the mold 3-D file format, Z-Axis uppermost point extraction, elimination of unnecessary points, and final target point selection are sequentially performed. The Catmull- Rom algorithm is then applied to plan spline trajectory that allows the robot end effector to spray at a constant speed by following the extracted target points. The proposed algorithm is validated on the test bed of a shoe sole spray system. Through the proposed method, the adhesive can be uniformly dispensed to the sole of the shoe in an atypical shape without the process of extracting the work point using the vision system.
Citations
Citations to this article as recorded by
Hierarchical Path Planning Method for Automated Valet Parking Systems Chanyoung Lee, Kibeom Lee Journal of the Korean Society for Precision Engineering.2024; 41(5): 365. CrossRef
Automation of Shoe Upper Adhesive Spraying Process Using Robot Won Bo Jang, Sang Hyun Park, Seong Youb Chung, Myun Joong Hwang, Murim Kim Journal of the Korean Society for Precision Engineering.2023; 40(12): 981. CrossRef
This paper proposes an IMU method for location tracking in power plants and indoor environments without GPS. IMU-based sensors use accelerometer, angular accelerometer, earth magnetometer, and altimeter. It is a method for recognizing the movement of pedestrians or moving objects. However, errors can be caused, as noise and bias increase due to long-term measurement. VIO-SLAM type sensor T265, which uses a combination of cameras and IMU, and can accurately track paths in invisible spaces, is used in this study. In addition, this type of sensor can be corrected in real time with a filter function inserted into the sensor and errors can be minimized. As a comparison experiment with the encoder, it is possible to evaluate the location of the scanner within a ±10 mm error from the actual distance in 1,500 × 700 (mm) space. The usefulness of this method is verified by measuring real specimens of boiler pipes and tubes, which are the major components of power plants.
An elevating drone station is very useful when lifting and lowering the battery charging station for safe installation, maintenance, and energy efficiency of a drone operation. When drone station modules rise above the average roof level of neighboring structures they may receive a strong wind force; thus, understanding the physical phenomena of both the structures and fluid is important to understand the structure"s reaction to the wind force. However, most studies in the field of drone stations did not perform a structural safety evaluation under wind loadings. Therefore, in this paper, we carried out a fluid-structure interaction analysis to verify the design of the lifting-and-lowering-type drone station.
Angular contact ball bearings (ACBBs) are widely used in rotating machinery due to their heavy load-carrying capacity and excellent accuracy in high-speed operation. However, employing an ACBB requires a careful analysis because the characteristics of the ACBB significantly depend on the operating condition. The ball-race contact condition of an ACBB is one of the most important factors that can change its properties. This study deals with the ball-race contact behavior concerning several important parameters, such as rotational speed, unloaded contact angle, and external loading. Between the ball and race under loading, an elliptical contact area is formed, in which pure rolling lines may exist. In the region other than the pure rolling lines, sliding dominates due to differential slippage in the elliptical contact area. We investigated the behavior of ball-race contact in terms of the pure rolling lines. A computational procedure was presented to determine the pure rolling lines. Through simulations, it was found that rotational speed, unloaded contact angle, axial preload, and radial load significantly affected the number and locations of pure rolling lines. The presented results are useful for investigating and estimating the sliding friction torque for ACBBs.
Citations
Citations to this article as recorded by
Influencia del ángulo de contacto en la cinemática y la distribución de carga de rodamientos a bolas Pello Alberdi Quevedo, Ibai Ulacia Garmendia, Aitor Arana Ostolaza, Jon Larrañaga Amilibia, Aitor Oyanguren Garcia Anales de Ingeniería Mecánica.2025;[Epub] CrossRef
A general kinematic model for lubricated ball bearings based on the minimum energy hypothesis Pello Alberdi, Aitor Arana, Aitor Oyanguren, Jon Larrañaga, Ibai Ulacia Tribology International.2024; 196: 109698. CrossRef
Analytical formulation for sliding friction torque in cylindrical roller bearings Gilbert Rivera, Patrick John Po, Chan-sik Kang, Seong-Wook Hong Journal of Mechanical Science and Technology.2024; 38(9): 4669. CrossRef
Stiffness characteristics and experimental study of angular contact ball bearings considering the influence of rotational speed Runlin Chen, Fan Xu, Gengzhou Liu, Jiakai Li, Shaodong Zhao, Xingyu Fan, Yanchao Zhang, Saisai Lv Advances in Mechanical Engineering.2024;[Epub] CrossRef
Study on Thermo-mechanical Modeling and Analysis of High-speed Angular Contact Ball Bearings Under Oil-jet Lubrication Gilbert Rivera, Shinhyang Park, Chan-sik Kang, Dongjoo Kim, Seong-Wook Hong Journal of the Korean Society for Precision Engineering.2024; 41(7): 569. CrossRef
Improved Formulation for Sliding Friction Torque of Deep Groove Ball Bearings Gilbert Rivera, Van-Canh Tong, Seong-Wook Hong Journal of the Korean Society for Precision Engineering.2022; 39(10): 779. CrossRef
Until recently, solar energy has been considered as a promising regeneration energy source in the future. Solar cell wafer production involves ingot cutting, cleaning, and packaging processes. In this research, design, fabrication, and testing of a batch-type midsonic for cleaning solar cell wafers were carried out. To reduce the damage compared to conventional systems, we decided to use 400 kHz in a midsonic wave range, and we used far-field to obtain a more regular acoustic pressure. Finite element analysis with Ansys software predicted an anti-resonance frequency of 458 kHz for an ultrasonic waveguide, and the measured result of the fabricated system was 454 kHz with a 0.9% error. Acoustic pressures were measured, and the result confirmed regular and high distributions. Finally, cleaning tests were performed, and a 90% particle removal efficiency (PRE) was achieved at 900 W. Thus, the newly developed midsonic cleaning system can be considered to clean particles on solar cell wafers efficiently while preventing damage.
Knee contact forces and knee stiffness are biomechanical factors worth considering for walking in knee osteoarthritis patients. However, it is challenging to acquire these factors in real time; thus, making it difficult to use them in robotic rehabilitation and assistive systems. This study investigated whether trained deep neural networks (DNNs) can capture the biomechanical factors only using kinematics during gait, which is possible to measure via sensors in real time. A public dataset of walking on the ground was analyzed through biomechanical analysis to train and test DNNs. Using the training dataset, several DNN topologies were explored via Bayesian optimization to tune the hyperparameters. After optimization, DNNs were trained to estimate the biomechanical factors in a supervised manner. The trained DNNs were then evaluated using two new datasets, which were not used in the training process. The trained DNNs estimated the biomechanical factors with a high level of accuracy in both types of test datasets. Results confirmed that DNNs can estimate the biomechanical factors based on only kinematics during gait.
Additive manufacturing requires a relatively long time to fabricate complex three-dimensional (3D) structures or parts with more than one material. For additive manufacturing processes, production time and precision vary depending on the fabrication conditions. In this study, we developed a food additive manufacturing process of the material extrusion method type using a dual nozzle. In addition, we observed the change in the cross-sectional shape of the discharged food line according to each fabrication condition. By using a dual nozzle, the structure was fabricated under conditions of relatively high precision for the outer wall and relatively low precision for the infill, thereby shortening the production time. Through this process, it can be expected that the production time will be shortened in the food field, while the appearance will be of good quality.
First
Prev
