The use of environmentally friendly, lubricant-free plastic seals in the rotating parts of robots and machines is on the rise. However, variations in seal geometry and operating conditions can influence the contact pressure between the seal and shaft, potentially leading to poor sealing performance, premature wear, or debris ingress. Therefore, advanced design optimization is essential. In this study, we conduct a parametric study and sensitivity analysis to enhance the performance of plastic seals. Finite element analysis (FEA) is carried out using a 2D axisymmetric model with interference fit contact conditions to accurately simulate the behavior of the seal and shaft. We verify the reliability of the analysis by comparing the deformation of the seal diameter before and after shaft insertion with experimental measurements obtained using a 3D tactile measurement device. We analyze four design variables: pressure, temperature, seal diameter, and coefficient of friction, considering seal contact pressure as the objective function. Sensitivity analysis is performed to determine the impact of these design variables on contact pressure and to identify trends.

Drone stations are increasingly being applied to enhance the mission capabilities of drones. The drone’s station landing occurs in a limited space. A relative position communication signal between the drone and the station is required. Strong, precise control over communication signal interference is required. In this paper, we describe a filter processing method for position signal processing. In consideration of the anchor position and installation angle of the UWB module of the drone station, nine performance test cases were proposed. As a result of the performance test, high position accuracy output was confirmed when considering the result of minimizing signal shading and beam pattern direction with excellent reception sensitivity. A performance test was conducted using the developed drone station, and the landing performance was confirmed with a precision of within 20 cm.

A novel method for the development of a highly sensitive triboelectric sensor based on porous PDMS matrix and carbon black (CB) particles is proposed. The porosity of the PDMS is controlled by using wet sugar particle sizes, and we fabricate a porous PDMS plate with a pore-to-volume ratio of 46%, which has a larger internal contact area compared to a non-pore one. To investigate the sensitive responses of the sensor, two key processes for the deposition of CB particles are conducted. One is the stirring process and another is ultrasonic vibration waving process. Based on the proposed method, a high-performance flat triboelectric sensor is fabricated. By a weight drop test of two different sensors, the amount of out-voltage is changed to approximately 29.1 and 95.1%, respectively. Through this study, we can evaluate that the sensitivity of triboelectric sensors is affected by the deposition method of the CB particles. The proposed flexible triboelectric sensor can be applied to analyze human physical behavior. Also, we believe that it can be applied to measure various physical signals such as contact force or gripping force with small values.

Recently, large-scale accidents caused by minor damage from fatigue failure and impact on structures have been frequently reported. Therefore, a real-time damage monitoring system of structures is considered to be one of the most important technologies to ensure safety in various types of research. The piezoelectric sensor, which has an advantage of converting deformation of a structure into an electrical signal without using an additional power source, has been reported as one of the most suitable methods for real-time monitoring systems. This review aims to describe the structural monitoring system utilizing piezoelectric paint sensors. First, we present the concept of a piezoelectric paint sensor with the advantages of flexibility and piezoelectric performance. Then, factors affecting the performance of the piezoelectric paint sensor are introduced. Finally, an overview of piezoelectric paint sensors for structural monitoring, such as vibration detection and impact monitoring, are provided. The state-of-the-art of the application of the piezoelectric sensor is also introduced, providing feasibility in industrial fields.

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.

Precision positioning stages are devices for precisely positioning objects according to required degrees of freedom and performance. Precision positioning stages are classified into serial and parallel mechanisms. Except for specific applications, the parallel mechanism is preferred. In serial mechanism, dynamic characteristics such as resonant frequency are clearly different from axis to axis and the first resonance frequency is distinctly low compared to the second. These make the control performance different for each axis and incurs limitation in control. In this study, the first and second resonant frequencies in a serial 2-DOF precision positioning stage were increased while maintaining their approximal value. Compliance analysis for the stage was performed by applying the matrix based method. A new concept of resonant frequency isotropy (RFI) was introduced and design optimization was performed in which first and second resonant frequencies almost coincided. This optimization allowed for the design of a serial 2-DOF precision positioning stage with enhanced first resonance frequency by 50.8% and RFI by 80.2% compared to the initial design. This paper is expected to increase the use of precision positioning stages based on serial mechanism and apply the concept of RFI to the positioning stages with more than 2-DOF.