Abstract: The use of industrial robots is widespread in diverse manufacturing fields. Hence, there have been attempts to use robot for machining processes instead of machine tools. However, limited machining accuracy has been a major obstacle hampering the adoption of robotic machining systems. Recently, substantial research has been carried out to address this issue. In this paper, recent progress in robotic machining has been summarized, such as kinematic calibration and compliance error compensation to improve the accuracy of robotic machining. Auxiliary units for improving the performance of robotic machining systems are also discussed.

Abstract: Thickness is a typical parameter related to length, of which measurements are conducted in various industrial fields, such as the automotive, aviation, ship-building, semiconductor, and display industries. Among various measurement techniques, optical interferometry is very attractive in terms of reliability owing to the direct realization of the metre. Moreover, the nature of this non-contact method is such that it does not damage samples. In this review, optical interferometric methods for measuring thicknesses of thick transparent layers are introduced through a discussion of basic principles and applications. With consideration of optical layouts and analysis methods of interference signals, monochromatic laser interferometry, low-coherence interferometry, and spectral interferometry are introduced and discussed in chapters 2, 3 and 4, respectively. With regard to spectral interferometry, the two different key technologies of spectrally resolved interferometry and wavelength-scanning interferometry are covered in different subsections of chapter 4.

Abstract: In this paper, we propose a convolutional neural network (CNN) based method that inspects non-patterned welding defects (craters, pores, foreign substances and fissures) on the surface of the engine transmission using a single RGB camera. The proposed method consists of two steps: first, extracting the welding area to be inspected from the captured image, and then determining whether the extracted area includes defects. In the first step, to extract the welding area from the captured image, a CNN based approach is proposed to detect a center of the engine transmission in the image. In the second stage, the extracted area is identified by another CNN as defective or non-defective. To train the second stage CNN stably, we propose a class-specific batch sampling method. With our sampling method, biased learning caused by data imbalance (number of collected defective images is much less than that of non-defective images) is effectively prevented. We evaluated our system with a large amount of samples (about 32,000 images) collected manually from the production line, and our system shows a remarkable performance in all experiments.

Abstract: The components built using new generation feature based design and manufacturing process, called laser additive manufacturing (LAM) is inherited with tensile residual stress due to rapid heating and cooling during material processing. Laser shock peening (LSP) is an advanced surface engineering process that imparts beneficial compressive residual stresses into materials yielding longer product life by increasing the resistance to many surface-related failures, such as wear. LSP is widely used by various industries including aerospace, power generation, chemical processing, etc. to increase the life of engineering components. This paper reports LSP of LAM built Inconel 718 and the parametric study is conducted by varying peak laser power and number of shots at three different levels. Optimum laser power and number of shots derived using grey relational analysis is found to be 170 mW and 7, respectively for maximum hardness and minimum depth of profile. The investigation show that LSP changed the surface morphology and mechanical properties of the LAM built structure. The surface investigation using optical profilometer and Vickers micro-hardness shows a maximum profile depth of 10 μm and hardness of 360 HV. Residual stress measurement indicates compressive residual stress of 214.9–307.9 MPa on the LAM sample surface after LSP. The wear studies show an improvement by a factor of 1.70 for LSP treated LAM samples as compared to that of as-built condition. This study unwrap avenues for using LSP as property enhancement post-processing technique LAM fabricated structures with geometrical complexities.

Abstract: With the rapid development of the industry, the demand for new materials is increasing. However, new material development is time-consuming and costly. In this study, we proposed a workflow that uses data to create a materials model that accurately reflects the properties of materials. Six different numerical models for predicting the fatigue strength of steels were constructed with an empirical dataset extracted from a certified database (NIMS MatNavi material database). Because it is very difficult to understand the structure and patterns of large amounts of datasets and develop good predictive models at once, we have sought reliable models through statistical inference analysis, which has not been done in previous studies. We also chose the highest performance model with the accuracy (R2 = 0.9850) by applying the latest XGBoost algorithm. Through further study, we believe that this workflow can be used to develop predictive models on various properties of materials.

Abstract: Laser cladding has been applied to reduce the wear on rails in a curved track. It is important to evaluate the wear and rolling contact fatigue (RCF) characteristics of laser cladding rails. This paper evaluated the wear characteristics of three types of laser cladding, i.e., Stellite 21, Inconel 625, and Hastelloy-C. The wear of Stellite 21 was reduced by 83% as compared to the untreated rail specimen, while those of Inconel 625 and Hastelloy C were decreased by 42% and 29%, respectively. Meanwhile, when laser cladding is applied, a cladding boundary between the rail and the laser cladding is created. The cladding boundary consists of the rail base material, the heat-affected zone, and laser cladding. At the cladding boundary, various types of microstructures are distributed, and as a result the hardness changes. The wear and RCF characteristics of the cladding boundary caused by rolling contact loads have been evaluated through twin-disc tests. Since Stellite 21 has low hardness at the cladding boundary, it suffered the most severe wear and damages in three types of laser cladding. If laser cladding is applied to reduce the wear of the curved track, the damage of the boundary, as opposed to the wear characteristics, should be taken into consideration. In this paper, Stellite 21 exhibits the best wear characteristics, but Hastelloy C is found to be the most appropriate when simultaneously considering both the wear and RCF of the cladding boundary.

Abstract: Friction stir spot welding (FSSW) is a solid state joining technique with a simple concept. A non-consumable rotating tool with a specially designed pin and shoulder are inserted into the sheets or plates to be joined. In this study, the effect of vibration on microstructure and thermal properties of Al5083 weldment made by FSSW using rotation speed of 1500 rpm and different dwelling times, namely 5 and 10 s, was investigated. This new method was entitled FSSVW (friction-stir-spot-vibration welding). The experimental and numerical results, obtained using Abaqus software, were compared. In this work, the Johnson–Cook hardening condition was used for modeling of deformable metals. The results showed good comparability between experimental and FEM data. Also, metallography analyses indicated that the grain size decreased and the temperature increased as FSSVW method was applied. The results showed that vibration during FSSW leads to grain size decrease of about 30–50% in the weld region.

Abstract: Titanium alloy is a highly specific strength material, having excellent mechanical characteristics such as high stiffness, fracture resistance, and hardness at high temperature, so it is applied to various fields such as automotive, aerospace and bio-industry. Yet, the excellent characteristics of titanium alloy generate high cutting heat in cutting process, stimulating tool wear and degrading process accuracy. This study looked into turning characteristics of Ti–6Al–4V alloy using super light, coated carbide and cermet tool and applied Taguchi method to identify factors affecting turning process. In the process of titanium alloy, the major cause of tool wear was adhesion of the chip by cutting heat at a high temperature, and to enhance tool life, cutting speed control is necessary. Factors affecting tool life were in the order of tool material, cutting speed and feed rate.

Abstract: Biologically inspired or mimetic approaches have been traditionally widely adopted in robotic creative design. Generally, the most considered source for biorobotics and soft robotics are animals. Rarely, plants have been considered as a model of inspiration for innovative engineering solutions owing to their inconspicuous motion principles. In this work, a new type of plant-inspired soft robotic gripper was created by reconstructing and simulating the leaf structure and head formation mechanisms of cabbage. Firstly, according to the research reports of biological morphology and curling development mechanism of cabbage leaves, we determined that the flexible leaf with special hierarchical veins is the biological structure basis of curling formation. In the light of this observation, we designed a cabbage-inspired leaf bionic structure using paper substrate as a leaf body and using polylactic acid (PLA) polymer as leaf veins. This bionic design schema of cabbage leaves first has the advantage of ease of manufacture using 3D printing technology. In addition, due to the shape memory effect of PLA, we can control the reciprocal deformation of bionic leaves by controlling the temperature field. Undoubtedly, when two or more pieces of such bionic leaves are assembled together, they can be considered as a soft robotic gripper. Furthermore, we thoroughly studied the embodiment design of this bionic design concept as well as its 3D printing process. Finally, we built a prototype of this cabbage-inspired soft robotic gripper and successfully performed small objects (e.g., spitballs and cylinders) grasping experiments. Obviously, this research achievement first successfully integrated the bionic structure of plant deformation, direct digital manufacturing, and the control of shape memory materials. Secondly, this work realized the unified design of the structure, function, driving, and fabrication of robotics, and further expanded the family of the bionic robot, especially plant-like or plant-inspired robotic solutions.

Abstract: Nomex honeycomb core materials have been widely used in the aviation industry due to their special structure and performance. Conventional high-speed machining have resulted in the poor machinability of the honeycomb core so that the ultrasonic machining technology was applied. The kinematic characteristics in the ultrasonic vibration assisted cutting process were analyzed according to the movement of the sharp tool. Based on slide effect, a cutting force model was proposed to study the relationship between cutting parameters and cutting force. Ultrasonic vibration assisted cutting and ordinary cutting tests of Nomex honeycomb core material were conducted by considering feed rate, the inclined angle and the deflected angle. Besides, the effects of cutting parameters on machined surface quality of honeycomb core wall were studied. The test results show that slide effect caused by ultrasonic vibrations can reduce cutting resistance compared with ordinary cutting. The developed cutting force model can be applied to evaluated the cutting force in the ultrasonic vibration assisted cutting of Nomex honeycomb core material. The inclined angle has a great influence on the cutting force during ultrasonic vibration assisted cutting. High-speed reciprocating sliding action can effectively cut aramid fibers so that burrs and tearing defects of the incision have been greatly improved under condition of ultrasonic vibration assisted cutting.

Abstract: In the paper, a novel passive vibration isolator is proposed for an ultra-precision sensing system, utilizing a quasi-zero stiffness (QZS) mechanism. The QZS mechanism implements the high static low dynamic stiffness, which effectively reduces the dynamic force transmission while minimizing the static deflection under the natural frequency of conventional passive isolator. Furthermore, it does not need any electric components; the mechanism is suitable for the ultra-precision sensing systems measuring extremely weak electromagnetic fields. However, nonlinear stiffness and hysteresis caused from the negative stiffness elements degrade the system performance. A vertical spring with a pre-tension and eight horizontal plate springs with nonlinear buckling characteristics constitute the proposed system to solve these problems. The mathematical model compares the negative stiffness design with previous QZS research. The buckled plate spring with ball joint design reduces stiffness variation. Transmissibility of the proposed system for low frequency range is investigated experimentally.

Abstract: A set of samples of glass fiber reinforced polymer composites with Teflon inclusions in the shape of pentagram have been specifically designed and fabricated for the purpose of assessing the efficacy and practicality of terahertz (THz) time domain spectroscopy (TDS) system in non-destructive evaluation (NDE), in side-by-side comparison with X-ray computed tomography (CT), and ultrasonic imaging. The samples feature systematic variation of Teflon inclusions of a variety of thicknesses and placement depths. An improved THz imaging algorithm is proposed and demonstrated to enhance the capability of THz-TDS detection by adding an appropriate window for sampling the reflected time-domain waveform a posteriori. Additionally, image fusion algorithm based on block segmentation is applied to combine multiple imaging detection results, leading to further improvement of the final defect detection capability. Comparative analysis of the detection results among THz-TDS, X-ray CT, and ultrasonic imaging is carefully carried out to assess the merits and disadvantages of each technique, and to attempt to find a proper place for THz-TDS imaging in the traditional arsenal of NDE tools.

Abstract: Fault diagnosis plays a key role in monitoring manufactured products for the purpose of quality control. Among the several fault diagnosis approaches, knowledge-based fault diagnosis, which uses signals from sensors and machine learning algorithms instead of a priori information, is widely employed to diagnose the status of products. In this paper, we propose a knowledge-based procedure to establish a fault diagnosis model. The model is aimed to diagnose planetary gear carrier packs, which have many fault types and an unbalanced number of samples in the sample classes, using transmission error. In the procedure, the best feature subset that contains the most important features is selected using two different feature selection processes. Several ensemble algorithms are used during the model training process. The imbalance ratio between classes of samples is addressed. The number of weak learners is automatically determined by a genetic algorithm. Finally, the performance of the proposed procedure is validated by comparison with other models trained without applying the proposed procedure. We observed that it is important to incorporate the class imbalance technique in the training process as it reduces the misclassification of faulty products as normal ones. This reduction is important in production quality control.

Abstract: Fault detection and diagnosis of the induction motor is important to prevent the system downtime of industrial fields. Most of the fault detection and diagnosis is conducted in the frequency domain using fast Fourier transform (FFT). Although several studies have been done using FFT, this method has difficulties in finding the fault characteristic frequency component. To overcome these difficulties, this paper provides the algorithm using principal component analysis (PCA) to easily find the feature of the FFT signal and utilize the Hotelling’s $$T^{2}$$ as an index for fault detection. After selecting the peak of top five frequencies and corresponding amplitude of the FFT as a feature and reducing the dimension through PCA, it is possible to detect a motor abnormality through Hotelling’s $$T^{2}$$ value. The proposed method is verified for detecting abnormal states of three-phase squirrel-cage induction motor. It has been confirmed that using the fault characteristic frequency component of both frequency and corresponding amplitude is more accurate in determining the motor abnormality than the characteristic of only frequency.

Abstract: Measurement and detection of ground information by airborne Lidar are one of the hot topics in the field of intelligent sensing in recent years. This study proposes a new point cloud classification algorithm of Mixed Kernel Function SVM to distinguish different types of ground objects. Firstly, the combined features including the coordinate values, the RGB value, normalized elevation, standard deviation of elevation, and elevation difference of point cloud data were extracted. A mixed kernel function of Gauss and Polynomial was designed. Then, one-versus-rest SVM multiple classifiers was constructed. Finally, the feature of 3D point cloud data was employed to train the SVM classifiers. The overall classification accuracies of test data were 97.69% and 99.13% for two data sets, I and II respectively. In addition, the experimental results have showed that the performance of the proposed method with mixed kernel function SVM was better than standard SVM method with Gaussian kernel function and polynomial kernel function only, which demonstrates the effectiveness of the proposed method.

Abstract: A robust algorithm to classify various hand postures using EMG signals is needed for the EMG-based electric hand prosthesis with the multiple degrees of freedom. In this study, an armband-type multi-channel EMG module was designed, and an algorithm for classifying seven different types of hand postures was developed using the artificial neural network (ANN). The classification accuracy was evaluated for ten normal volunteers, according to the independence of the EMG feature groups, donning and doffing training data size, and whether or not majority voting was applied. The results revealed an optimized accuracy of 97.49 ± 3.87% when majority voting was applied after using high independence feature group (HIFG) to perform classification training for seven or more sessions. The algorithm was successfully applied to provide seven different hand postures in a 5-finger myoelectric hand prosthesis. Confusion matrices and separability indexes of ANN classifiers showed that the major misclassifications, in spite of a good accuracy, were found to be lateral pinch versus palmar pinch, and index versus thumb-up. However, with the classification training for seven or more sessions, the probability of misclassification significantly decreased.

Abstract: A transformation algorithm compensating a radius of the probe tip and pre-travel errors is proposed to improve measurement uncertainty of a coordinate measuring machine (CMM). The transformation algorithm does not only compensate a radius of the probe tip, but it also compensates a slipping displacement from the predicted contact point caused by vertical tension for each data point. The performance of the transformation algorithm was successfully demonstrated by applying the transformation algorithm to raw data of an on-axis lens and an off-axis mirror measured with the CMM and comparing them with a reference data measured with UA3P-5 having several tens of nanometer accuracy.

Abstract: The direct measurement of grinding temperature is always difficult due to coolant cover and very size of work and wheel interaction zone. At the same time, high heat generation in grinding often leads to grinding burns thereby affecting surface integrity; in this context, theoretical evaluation of temperature could facilitate early detection of the grinding burns. This paper therefore presents an analytical model to evaluate grinding temperature and correlates it with the occurrence of grinding burns in terms of BNA. In general, the analytical approach involves evaluating real contact length, grinding forces and finally grinding zone temperature for the plunge cylindrical grinding. The maximum rise in grinding temperature at the surface was calculated, for the wet grinding process by considering the total heat flux entering into the grinding system. Model validation experiments have been performed to measure BNA and identify parametric conditions that produce grinding burns. The model estimate of grinding zone temperature of 631 °C is in good agreement (92%) with other research works. Further, when the calculated grinding temperature reaches beyond 631 °C, the grinding burns are observed on the work surface with a BNA value of the order of 100 mp for the micro alloyed steel. The minimum thermal damage in terms of BNA is observed at higher levels of wheel speed and spark-out time and lower levels of depth of cut.

Abstract: This paper presents a novel method to generate three-axis CNC tool paths for machining freeform surfaces based on a preferred feed direction field. This research was initiated from a fluid dynamics behavior that the energy loss can be reduced when the streamlines of fluid and the small grooves on a surface are in the same directions. In this research, the fluid streamlines above the surface are defined by a collection of vectors. These vectors are regularized into a grid of vectors, and these regularized vectors are further projected onto the tangent planes of a grid of points on the surface to create the preferred feed direction field. Based on the parametric model of the surface, the vectors on the tangent planes of the surface are mapped into vectors in the parametric domain. A scalar function is constructed such that the isolines of this scalar function and the preferred feed direction vectors in the parametric domain are in the same directions. A group of isolines of the scalar function are identified and these isolines are mapped back onto the 3-D surface as the created tool paths considering the tolerance requirement. The developed method has been applied to generate the tool paths for machining surfaces of a compressor blade.

Abstract: The present study investigated the effect of different machining environments such as dry, wet, cryogenic cooling, minimum quantity lubrication (MQL), Al2O3 nanofluids with MQL, CuO nanofluids with MQL and Al–CuO hybrid nanofluids with MQL on machining performance characteristics during turning of EN-24 steel The nanofluids and hybrid nanofluids were prepared by adding different weight percentages (02 wt%, 04 wt%, 06 wt%) of Al2O3, CuO and Al–CuO to the soluble oil The thermal and tribological properties of soluble oil, nanofluids and hybrid nanofluids were analysed The thermal conductivity of Al–CuO hybrid nanofluids was more compared with Al2O3, CuO nanofluids The specific heat of Al–CuO hybrid nanofluids was less compared with Al2O3, CuO nanofluids The comparative analysis of machining performance was done during turning under different environments Experimental results reveal that the turning performance under Al–CuO hybrid nanofluids with MQL was better as compared to other machining environments

Abstract: Chemical mechanical polishing (CMP) is essential in semiconductor processing and has recently widened its scope of application. However, the study on its mechanisms is still in progress. Understanding the CMP process requires an understanding of the various physical and chemical reactions that occur at the pad-wafer interface. Moreover, understanding the real contact area (RCA) between the polishing pad and the wafer in the CMP process is essential for predicting the material removal rate (MRR) and understanding the overall process. In this study, a modified mathematical model for the RCA was developed and validated experimentally. The model of the RCA proposed in this study was used to establish the MRR model and predict the MRR under various pressure values and the effect of abrasive particle size and its distribution. Specifically, the experimentally obtained values were compared with the values obtained by the model and the comparison results were analyzed. Thereby, it was found that the RCA model and the MRR model proposed in this study were in good agreement with the experimental results, which shows that the MRR can be predicted by a mathematical model using the measurement of the RCA.

Abstract: In the directed energy deposition (DED) process, the scanning speed around sharp corners decreases from the command speed to a capable-curve speed. At a constant powder feed rate, the reduction in the scanning speed causes oversized beads owing to the increased deposition amount per unit time. In this study, the excessive deposition at the corners is controlled by the tailored setting of the corner scanning speed. The proposed control method enables fabrication of an equal-height rectangular corner geometry using the DED process. The bead height along the rectangular corner is controlled to be equal to those of the linear segments. For the sensitivity analysis of the process parameters, the effect of the scanning speed, laser power, and powder feed rate on the bead deposition was investigated experimentally. To generate smooth and equal-height deposition, a corner scanning-speed control algorithm was applied. Results showed that over deposition occurred near the corner section due to the scanning speed drop but after applying the controlled scanning speed, over deposition was decreased. In addition, a three-dimensional thermo-mechanical finite element simulation was performed to investigate the temperature field and induced residual stresses.

Abstract: In the hot forging process of aluminum piston using water-soluble lubricants, the lubricant layer is often peeled off due to excessive deformation of the material during forming, which may result in direct contact between the material and the die, thereby partially increasing the friction. The constant friction in the Finite element (FE) analysis of this process sometimes results in a completely different result from the actual material flow. Therefore, this study was designed to investigate the friction condition to accurately predict the material flow in the FE analysis. The FE analysis was performed for various material temperatures and friction parameters and the proper friction condition was also derived to remove forging defects. Finally, the forging test was carried out for the initial specimens produced by three different methods to verify the analytical results and eliminate the forging defects. The results showed that the friction depends on the effective strain in the FE analysis and the critical value to increase friction is approximately 1.5–1.8. In addition, among the three different specimens, the shot peened specimen can remove the forging defect by increasing the amount and uniformity of the lubricant on its surface.

Abstract: Physical vapour deposition technique was used to deposit TiAlCrN coatings on the YT15 tungsten carbide inserts. The dry turning tests of 20CrMo steel were carried out to evaluate performances of TiAlCrN coated and uncoated tools on the CA6140A lathe. The effect of the two kinds of tools on cutting forces, cutting temperature, surface roughness and tool wear had been investigated to assess the performance of TiAlCrN coated tools. The results showed that the cutting force and cutting temperature obtained by TiAlCrN coated tools were decreased and the TiACrN coated tools produced a better surface finish in comparison with the uncoated tools. The TiAlCrN coated tools yield working life about 45 min, which was two times of that for uncoated tools. The wear mechanisms of the TiAlCrN coated tools were mainly oxidation and boundary wear, accompanied with diffusion wear.

Abstract: Roll-to-roll printing equipment can be used to manufacture flexible electronic devices with multilayer structures. This manufacturing process requires both precise tension control of the web and high register accuracy between printed layers. Because of the high temperature of the dryer required for sintering inks, the web after printing undergoes considerable shrinkage. This shrinkage brings out an accumulated phase difference between each of the printing layers and a linearly varying term in the register errors. This error can be removed by elongating the shrunk web, or by transferring the web at the same linear velocities using rollers with identical diameters. However, the elongation causes high increase in tension that can damage the previously printed layer. Moreover, a very small difference between the diameters of the printing rollers because of the tolerance in the machining process of the roller can still produce a linearly varying term in the register errors although the web has recovered from shrinkage. This paper proposes a linear dancer system to remove the linearly varying term of the register errors caused by small difference in the diameters of the printing rollers. The dancer system is designed to synchronize the velocity of the second printing roller with the movement of the dancer to ensure that the dancer controls the tension within a limited range of movement of the dancer. Simulations as well as experiments show that the proposed dancer system and control method can eliminate the linearly varying register error and control the tension effectively. As a reverse application of the proposed method, it is also presented that a larger difference between the diameters of the printing rollers can decrease the stabilized tension for elongating the web to compensate for the shrinkage, which can reduce possible damage to previously printed layers during the manufacturing process of printed devices.

Abstract: The scientific and reasonable prediction of energy consumption in WEDM process is the key for energy-saving optimization of wire-cutting process in the design stage. The existing research about WEDM energy-saving studies mainly focus on the pulsed power control strategies. And, the research on non-pulsed energy consumption of WEDM is deficient. The non-pulsed energy consumption takes up a larger proportion in the whole WEDM process through theoretical analysis and case verification, and the energy consumption characteristics are equally representative. Therefore, the paper analyzes the energy characteristics based on non-pulsed energy consumption subunits of WEDM. A non-pulsed auxiliary energy consumption and feeding energy prediction model is established, and a WEDM machine tool is used for the experiment. The accuracy of the prediction model proposed in this paper can reach more than 96%. The raise and establishment of the model provides the basis for energy saving optimization of the subsequent wire cutting process.

Abstract: This paper presents the design, fabrication and testing of a solid polymer microneedle. Mechanical behavior of the microneedle was simulated by ANSYS via the results of suffered and strength calculations. The results shows, that the maximum stresses of polymer MNs is far less than 3.183 MPa, which is the allowable pressure needed. Taguchi method was used help in data analysis and prediction of optimum parameter settings, a series of experiments were conducted to verify the impact of embossing temperature, embossing pressure, and embossing time on the microneedle’s quality. According to the result from the Taguchi experiment, S/N ratio is calculated to find the best combination settings for microneedle’s height. The highest value of S/N ratio (54.403) for product height is determined as optimal initial parameter settings, achieved by 130 °C, 11 MPa and 150 s for PMMA microneedle with optimized size of 550 µm height, 250 µm base diameter and 50 µm tip diameter. Embossing temperature and embossing pressure are the significant parameters in the experiment. The proposed method was verified by a set of experiments, the force for insertion as well as the modes of mechanical failure were examined.

Abstract: In this research, a three-modular obstacle-climbing robot is suggested for the operation of a window-cleaning system on the facade of buildings. The suggested robot is composed of a main platform and three modular climbing units. The middle module has the window-cleaning system that performs the cleaning task using a roll-brush, water and detergent, a squeezing pad, and a suction device. Various sensors are installed in each climbing module to detect obstacles and measure the states of the robot and the wall. A winch mechanism is set on the top of the building to facilitate the vertical motion of the robot. The robot controller coordinates the three modules as well as the winch to climb obstacles. To evaluate the performance of the developed robot prototype, a 6-m-high test bed was set up on the roof and the facade. The obstacle size and time required to climb the obstacle were selected as the performance indices. In addition, quantitative and qualitative evaluation of the window-cleaning system were performed. As a result, it was confirmed that the obstacle-climbing robot could climb obstacles of varying sizes with reasonable speed while it performed the window-cleaning function. This research shows that a systemically well designed robot with a combination of simple sensors and actuators can solve the practical problem and apply in built buildings.

Abstract: We herein propose a cutting force model in a micro-dimple pattern process using the two-frequency elliptical vibration texturing (TFEVT) method. The TFEVT method decreases the cutting force compared to the conventional texturing (CT) method owing to the intermittent cutting behavior. The cutting force model in the TFEVT method is formulated, in which the shear angle is assumed as a transient and the transient area of cut of the micro-dimple is determined. The transient area of cut of the micro-dimple can be determined by obtaining the starting and ending time of cutting, while the shear angle can be determined by Cerniway’s hypothesis. Finally, the cutting force model was compared with the experimental cutting force value. The comparison results show that the cutting force simulation is in agreement with the experimental cutting force value. The experimental results also show that the cutting force in the TFEVT method is lower than that in the CT method.