Experimental design of 4-point supported belt robot for sanding large convex surfaces.

In general, sanding robots that move as if drawing a line along a surface are mainly used when sanding objects with a large area; however, they require a long working time, and it is difficult to secure a uniform sanded area. This study focuses on large-area sanding robots, such as those for ships, storage tanks, and tank lorries, and proposes an adaptive belt tension robot equipped with a 4-point supported belt mechanism capable of sanding variable curved surfaces. In addition, a sanding normal force prediction formula is proposed to describe the sanding performance of the contact surface. This equation consists of the concentrated load function due to the belt movement and the normal force due to the vertical and horizontal elongation of the belt. A video image analysis was performed to calculate the sanding area. Therefore, we determined whether the area was uniformly sanded. The dimensions of the test bench (W × D × H) were 1700 mm × 1450 mm × 900 mm. Experiments were performed using the proposed techniques on convex specimens with radii of 725, 1000, and 2100 mm. The sanding performance was improved by 43 % compared with that of a general belt-sanding robot.

2 DOF transformable wheel design based on geared 8 bar parallel linkage mechanism.

This paper introduces a novel design and static optimization for a two-degrees-of-freedom transformable wheel based on a geared linkage mechanism. Overcoming obstacles, including stairs, with small wheels is a major challenge in the field of mobile robotics research. Among various robots, the transformable wheel, which can change the shape of the wheel to overcome steps and optimize the path, was presented and has undergone many improvements. Nevertheless, problems such as asymmetry and structural strength remain. Therefore, the design of this paper aims to address the structural inefficiencies identified in the previous research model, which were attributed to the asymmetric placement of the linear motion guide. Through the implementation of this mechanism, the linear motion of the lobe can be segregated, enabling each input motor to share the workload effectively. The optimization process focus on determining the optimal linkage length under static conditions, resulting in improved structural characteristics and force distribution of linkage within the designated workspace. As a result, asymmetry of motion is eliminated, required intervention angle of the driving motor and stress of linkage was reduced by 36.24% and 8.35%, respectively.

The stiffness adjustable wheel mechanism based on compliant spoke deformation.

This study proposes a variable-stiffness mechanism for non-pneumatic tires such that can actively adapt to various environments. Non-pneumatic tire is a compliant wheel structure that offers superior robustness and adaptability compared to pneumatic tires. However, the tire designed for certain terrain exhibits relatively high rolling resistance and inadequate suspension. To address these problems, a stiffness-adjustable wheel (SAW) that can modify the force applied to the contact surface is introduced in this study. In addition, the shape of SAW is optimized to maintain a desirable range of stiffness under different conditions. The optimization is conducted with experimental method, because nonlinear response of material and interference between components make it difficult to predict the characteristic of the wheel at large deformation. The SAW has potential for application in various mobile platforms to provide adequate stiffness for a variety of terrains and driving conditions.

Slip considered path planning of a novel angled-spoke based robot in a terrain mixture of granular media and rigid support.

Navigation in terrains mixture of rigid support and granular media is associated with slippage. It is important to find the optimal path because slippage implies the possibility of a mobile robot being stuck in the sand. This research introduce concept of effective distance which consider effect of slippage to present a path planning algorithm. Effective distance is a conceptual distance that the mobile robot traverse to reach next node, and it is calculated based on traversable difficulty. Traversable difficulty varies with the slope angle, and the revolution speed of the angled spoke-based wheel (ASW) is estimated using meta-model. The meta-model is achieved empirically. Experiments have done in testbench which can implement slope angle and terrain types. Effectiveness of this algorithm was verified through simulation. For the simulations three cost determination methods, namely, the effective distance with varying revolution speed of the ASW, the effective distance with fixed revolution speed of the ASW, and actual distance were examined in four different scenarios. The effective distance with varying revolution speed of the ASW has maximum [Formula: see text] longer total actual distance. However, it results minimum [Formula: see text] shorter total effective distance.

Examining the mechanics of rope bending over a three-dimensional edge in ascending robots.

This paper presents the analysis of ropes' bending on three-dimension edges by ascending robots. A rope ascending robot (RAR) is a type of exterior wall-working robot that utilizes a synthetic rope to traverse the outer surface of a building. Rope-based façade cleaning robots demonstrate effective performance in well-structured buildings. However, in unstructured buildings, the rope used by these robots may become entangled or caught on various structures, presenting a significant challenge for their operation. If the rope becomes caught on a structure, the robot will be unable to move to its intended position. In more severe cases, the rope may become damaged, leading to potential failure or even a fall of the robot. Therefore, solving this problem is crucial for safe and efficient robot operation. Consequently, this study defines the issue of the rope becoming caught on a structure as a rope-locking problem and analyzes it by categorizing it based on the dimensions of contact between the rope and the edge. To address the varying tension experienced in different areas, the rope was divided into micro units and subjected to a three-dimensional analysis to resolve the rope-locking problem. Additionally, the analysis was verified by experiments.

Empirical optimization of an angled spoke paddling wheel with self-rotating mechanism.

The development of the maritime industry has led to a corresponding increase in maritime accidents. Maritime accidents are major events that are costly to recover and can cause casualties. Moreover, individuals who are brought to the scene for recovery or rescue are at risk. To tackle this issue, the wheel mechanism of a water rescue robot, i.e., the angled spoke paddling wheel (ASPW), has been studied. The purpose of this study is to optimize the paddle design parameters of the ASPW using the Taguchi method. Experiments are conducted by creating paddles with various combinations of design parameters using [Formula: see text]([Formula: see text]) orthogonal arrays. The objective function is determining the optimal combination of paddle design parameters that will produce the greatest thrust force at the same RPM. Sensitivity analysis of each design parameter is conducted by calculating the signal-to-noise ratio from the experimental results. The pitch angle is found to be the most sensitive parameter. An additional experiment is conducted based on the results of the sensitivity analysis. The results show that the optimal design parameters are a pitch angle of [Formula: see text], rectangular end shape, X-axis curvature of 37.5 mm, and Y-axis curvature of 25 mm. The paddle with this combination of design parameters have a maximum thrust force of 64.74 gf at 120 RPM and exhibit up to an 18.27% improvement in performance compared with the initial paddle before optimization.

Design exploration and comparative analysis of tail shape of tri-wheel-based stair-climbing robotic platform.

Stair climbing is one of the most important capabilities of mobile robots. Therefore, stair-climbing mobile robots have become a field of study and diverse stair-climbing mobile robots have been developed. Although tri-wheel-based stair-climbing robotic platforms were developed to overcome the challenges posed by stair climbing, they have shown limitations such as impact during locomotion and damage owing to friction with the nosing of the stairs. In this study, several tail mechanisms were proposed and designed to solve the limitations of tri-wheel-based stair-climbing robots. A comparative analysis of the tail mechanisms was performed through dynamic simulations based on various performance indices. It was observed that the tail mechanism improved the stability and stair-climbing performance of the tri-wheel-based stair-climbing robots. The experimental verification confirmed the reliability of the comparative analysis results based on the simulation. These findings can be used to design mobile stair-climbing robots.

Design optimization of a linkage-based 2-DOF wheel mechanism for stable step climbing.

This paper presents the design optimization of a linkage-based wheel mechanism with two degrees of freedom, for stable step climbing. The mechanism has seven rotational joints and one prismatic joint. Kinematic and dynamic analyses of the mechanism were performed. The design was optimized in terms of linkage length and architecture to better manipulate the mechanism in its workspace, which was defined here by the targeted step size, as well as to ensure stability while climbing stairs. Optimization by genetic algorithm was performed using MATLAB. The optimized mechanism exhibited enhanced torque transmission from the input torque to the exerted for at the lobe of the wheel. Compliance control of the transformation will be addressed in the future.

Detection method for transparent window cleaning device, image processing approach.

Recent years, there has been an increase in the number of high-rise buildings, and subsequently, the interest in external wall cleaning methods has similarly increased. While a number of exterior wall cleaning robots are being developed, a method to detect contaminants on the exterior walls is still required. The exteriors of most high-rise buildings today take the form of a window curtain-wall made of translucent glass. Detecting dust on translucent glass is a significant challenge. Here, we have attempted to overcome this challenge using image processing, inspired by the fact that people typically use just the 'naked eye' to recognize dust on windows. In this paper, we propose a method that detects dust through simple image processing techniques and estimates its density. This method only uses processing techniques that are not significantly restricted by global brightness and background, making it easily applicable in outdoor conditions. Dust separation was performed using a median filter, and dust density was estimated through a mean shift analysis technique. This dust detection method can perform dust separation and density estimation using only an image of the dust on a translucent window with blurry background.

Honeycomb Artifact Removal Using Convolutional Neural Network for Fiber Bundle Imaging.

We present a new deep learning framework for removing honeycomb artifacts yielded by optical path blocking of cladding layers in fiber bundle imaging. The proposed framework, HAR-CNN, provides an end-to-end mapping from a raw fiber bundle image to an artifact-free image via a convolution neural network (CNN). The synthesis of honeycomb patterns on ordinary images allows conveniently learning and validating the network without the enormous ground truth collection by extra hardware setups. As a result, HAR-CNN shows significant performance improvement in honeycomb pattern removal and also detailed preservation for the 1961 USAF chart sample, compared with other conventional methods. Finally, HAR-CNN is GPU-accelerated for real-time processing and enhanced image mosaicking performance.

Real-time UVMS torque distribution algorithm based on weighting matrix.

This study presents a real-time algorithm for even distributing the torque burden on the parallel manipulator with an autonomous underwater vehicle (AUV) through the cooperation of the AUV and manipulator. For the redundant resolution of the underwater vehicle manipulator system (UVMS), we used the weighting matrix of the weighted pseudo inverse for kinematic and dynamic modeling. We made dynamic and kinematic modeling using the force distribution characteristics of parallel manipulators. Using the parallel manipulator's model, the weighting matrix was changed every second to share the manipulator torque with the AUV. The Taguchi method was used to reduce the calculation time for real-time calculation and to perform valve rotation operations with as little torque as possible even in an underwater environment where it is difficult to determine any cause of errors. To demonstrate the effectiveness of this algorithm, we experimented with valve rotation in water using the UVMS. Analysis of the experimental results revealed that the manipulator torque load was greatly reduced due to the AUV load distribution.

Effects of body movement on yaw motion in bipedal running lizard by dynamic simulation.

Lizards run quickly and stably in a bipedal gait, with their bodies exhibiting a lateral S-shaped undulation. We investigate the relationship between a lizard's bipedal running and its body movement with the help of a dynamic simulation. In this study, a dynamic theoretical model of lizard is assumed as a three-link consisting of an anterior and posterior bodies, and a tail, with morphometrics based on Callisaurus draconoides. When a lizard runs straight in a stable bipedal gait, its pelvic rotation is periodically synchronized with its gait. This study shows that the S-shaped body undulation with the yaw motion is generated by minimizing the square of joint torque. Furthermore, we performed the biomechanical simulation to figure out the relationship between the lizard's lateral body undulation and the bipedal running locomotion. In the biomechanical simulation, all joint torques significantly vary by the waist and tail' motions at the same locomotion. Besides, when the waist and tail joint angles increase, the stride length and duration of the model also increase, and the stride frequency decreases at the same running speed. It means that the lizard's undulatory body movements increase its stride and help it run faster. In this study, we found the benefits of the lizard's undulatory body movement and figured out the relationship between the body movement and the locomotion by analyzing the dynamics. In the future works, we will analyze body movements under different environments with various simulators.

Automated technique for high-pressure water-based window cleaning and accompanying parametric study.

The maintenance of buildings has become an important issue with the construction of many high-rise buildings in recent years. However, the cleaning of the outer walls of buildings is performed in highly hazardous environments over long periods, and many accidents occur each year. Various robots are being studied and developed to reduce these incidents and to relieve workers from hazardous tasks. Herein, we propose a method of spraying high-pressure water using a pump and nozzle, which differs from conventional methods. The cleaning performance parameters, such as water pressure, spray angle, and spray distance, were optimized using the Taguchi method. Cleaning experiments were performed on window specimens that were contaminated artificially. The cleaning performance of the proposed method was evaluated using the image-evaluation method. The optimum condition was determined based on the results of a sensitive analysis performed on the image data. In addition, the reaction force due to high pressure and impact force on the specimens were investigated. These forces were not sufficient to affect the propeller thrust or cause damage to the building's surface. We expect to perform field tests in the near future based on the output of this research.

Switching PD-based sliding mode control for hovering of a tilting-thruster underwater robot.

This paper presents a switching PD-based sliding mode control (PD-SMC) method for the 6-degree-of-freedom (DOF) hovering motion of the underwater robot with tilting thrusters. Four thrusters of robot can be tilted simultaneously in the horizontal and vertical directions, and the 6-DOF motion is achieved by switching between two thruster configurations. Therefore, the tilting speed of thruster becomes the most essential parameter to determine the stability of hovering motion. Even though the previous PD control ensures stable hovering motion within a certain ranges of tilting speed, a PD-SMC is suggested in this paper by combining PD control with sliding mode control in order to achieve acceptable hovering performance even at the much lower tilting speeds. Also, the sign function in the sliding mode control is replaced by a sigmoid function to reduce undesired chattering. Simulations show that while PD control is effective only for tilting duration of 600 ms, the PD-based sliding mode control can guarantee the stable hovering motion of underwater robot even for the tilting duration of up to 1500 ms. Extensive experimental results confirm the hovering performance of the proposed PD-SMC method is much superior to that of PD method for much larger tilting durations.

The Numerical Study of the Hemodynamic Characteristics in the Patient-Specific Intracranial Aneurysms before and after Surgery.

The patient-specific pre- and postsurgery cerebral arterial geometries in the study were reconstructed from computed tomography angiography (CTA). Three-dimensional computational fluid dynamics models were used to investigate the hemodynamic phenomena in the cerebral arteries before and after surgery of the aneurysm under realistic conditions. CFD simulations for laminar flow of incompressible Newtonian fluid were conducted by using commercial software, ANSYS v15, with the rigid vascular wall assumption. The study found that the flow patterns with the complex vortical structures inside the aneurysm were similar. We also found that the inflow jet streams were coming strongly in aneurysm sac in the presurgery models, while the flow patterns in postsurgery models were quite different from those in presurgery models. The average wall shear stress after surgery for model 1 was approximately three times greater than that before surgery, while it was about twenty times greater for model 2. The area of low WSS in the daughter saccular aneurysm region in model 2 is associated with aneurysm rupture. Thus the distribution of WSS in aneurysm region provides useful prediction for the risk of aneurysm rupture.

Drug-Eluting Stent Design is a Determinant of Drug Concentration at the Endothelial Cell Surface.

Although drug-eluting stents (DES) have greatly reduced arterial restenosis, there are persistent concerns about stent thrombosis. DES thrombosis is attributable to retarded vascular re-endothelialization due to both stent-induced flow disturbance and the inhibition by the eluted drug of endothelial cell proliferation and migration. The present computational study aims to determine the effect of DES design on both stent-induced flow disturbance and the concentration of eluted drug at the arterial luminal surface. To this end, we consider three closed-cell stent designs that resemble certain commercial stents as well as three "idealized" stents that provide insight into the impact of specific characteristics of stent design. To objectively compare the different stents, we introduce the Stent Penalty Index (SPI), a dimensionless quantity whose value increases with both the extent of flow disturbance and luminal drug concentration. Our results show that among the three closed-cell designs studied, wide cell designs lead to lower SPI and are thus expected to have a less adverse effect on vascular re-endothelialization. For the idealized stent designs, a spiral stent provides favorable SPI values, whereas an intertwined ring stent leads to an elevated SPI. The present findings shed light onto the effect of stent design on the concentration of the eluted drug at the arterial luminal surface, an important consideration in the assessment of DES performance.

Mathematical modeling of radiofrequency ablation for varicose veins.

We present a three-dimensional mathematical model for the study of radiofrequency ablation (RFA) with blood flow for varicose vein. The model designed to analyze temperature distribution heated by radiofrequency energy and cooled by blood flow includes a cylindrically symmetric blood vessel with a homogeneous vein wall. The simulated blood velocity conditions are U = 0, 1, 2.5, 5, 10, 20, and 40 mm/s. The lower the blood velocity, the higher the temperature in the vein wall and the greater the tissue damage. The region that is influenced by temperature in the case of the stagnant flow occupies approximately 28.5% of the whole geometry, while the region that is influenced by temperature in the case of continuously moving electrode against the flow direction is about 50%. The generated RF energy induces a temperature rise of the blood in the lumen and leads to an occlusion of the blood vessel. The result of the study demonstrated that higher blood velocity led to smaller thermal region and lower ablation efficiency. Since the peak temperature along the venous wall depends on the blood velocity and pullback velocity, the temperature distribution in the model influences ablation efficiency. The vein wall absorbs more energy in the low pullback velocity than in the high one.

Computational study of fluid mechanical disturbance induced by endovascular stents.

Arterial restenosis following stent deployment may be influenced by the local flow environment within and around the stent. We have used computational fluid dynamics to investigate the flow field in the vicinity of model stents positioned within straight and curved vessels. Our simulations have revealed the presence of flow separation and recirculation immediately downstream of stents. In steady flow within straight vessels, the extent of flow disturbance downstream of the stent increases with both Reynolds number and stent wire thickness but is relatively insensitive to stent interwire spacing. In curved vessels, flow disturbance downstream of the stent occurs along both the inner and outer vessel walls with the extent of disturbance dependent on the angle of vessel curvature. In pulsatile flow, the regions of flow disturbance periodically increase and decrease in size. Non-Newtonian fluid properties lead to a modest reduction in flow disturbance downstream of the stent. In more realistic stent geometries such as stents modeled as spirals or as intertwined rings, the nature of stent-induced flow disturbance is exquisitely sensitive to stent design. These results provide an understanding of the flow physics in the vicinity of stents and suggest strategies for stent design optimization to minimize flow disturbance.