The Experimental Research on Gear Eccentricity Error of Backlash-Compensation Gear Device Based on Transmission Error

Li Yu,Guangjian Wang,Shuaidong Zou 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.1

Backlash compensation is a research focus in precision gear transmission, and eccentricity error is the main factor which leads to transmission error(TE) with large period and periodically variable backlash in gear transmission, therefore, the eccentricity of gear has to be considered in anti-backlash. Firstly, the dual-eccentricity model for calculating the transmission error caused by eccentricity errors of gears is presented based on external parallel-axes gear transmission. Then, the tests are carried out at different input speed and initial starts for acquiring transmission error of the designed backlash compensation device, and the eccentricity error of the gear is identified from the testing data of transmission error by curve fitting based on the calculation model. Both the value and phase of the fitting eccentricity error are well coincident with the calculating model. Finally, the fast Fourier transform (FFT) is also employed to analyze the value of the eccentricity error. The results of the FFT are closed to the fitting values. The work is helpful for obtaining the eccentricity error of gear from the testing results of transmission error, which is useful for forecasting the TE caused by eccentricity error and provides important reference for backlash compensation and control.

MODELING TRANSMISSION ERRORS OF GEAR PAIRS WITH MODIFIED TEETH FOR AUTOMOTIVE TRANSMISSIONS

Lee, H.W.,Park, M.W.,Joo, S.H.,Park, N.G.,Bae, M.H. The Korean Society of Automotive Engineers 2007 International journal of automotive technology Vol.8 No.2

A tooth profile modification for loaded gears is used to avoid a tooth impact. Since a tooth profile error causes amplification of the cumbersome whine noise in automotive gear transmissions, an optimal quantity of tooth profile modifications must be obtained for good performance in the vibration sense. In this paper, a tooth profile modification curve considering profile manufacturing errors and elastic deformation of the gear tooth is formulated; in addition, transmission errors of the gear system with modified teeth are verified. The equivalent excitation due to transmission errors is formulated. For experimental evaluation of the transmission error, the transmission error for a simple gear system was measured by two rotational laser vibrometers. Finally, we perform a comparative analysis between the calculated and measured responses to the excitations due to the transmission error to verify the practicability of the application to automotive transmissions.

Multi-objective optimization of the tooth surface in helical gears using design of experiment and the response surface method

Park, Chan-Il 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.3

The design of tooth surface for low gear noise under various load conditions is very important, and gear noise is highly related to transmission error. Optimal tooth surface for reduction of transmission error is very difficult to analytically determine due to nonlinearity of transmission error and the need to satisfy multiple load conditions. Satisfying design variables in multiple load conditions leads to the Pareto optimum of multi-objective optimization. There, the method to determine optimal lead curve and robust tooth surface design is proposed, using the response surface method and multi-objective optimization. The effect of transmission error on the candidate design variables by a screening experiment has been investigated using analysis of variance. Design variables are likewise selected. The fitted regression model of transmission error is built with the statistic validation of the representation. The model with constraints is solved to obtain optimum lead curve design and robust design for the tooth surface under multiple loads.

사진 노이즈의 역용(逆用)에 관한 연구 -사진작품 <전송오류> 시리즈를 중심으로-

김정회,윤준성 한국기초조형학회 2020 기초조형학연구 Vol.21 No.5

The purpose of this study is to identify their methodological differences in various photo production methods using noise, and to clarify the modes as a ‘Noise Antistrophe’. In the use of photographic noise, there are the most well-known Glitch art, Photogram, Luminogram, and Transmission-error. Photogram and luminogram are analog-based methods for the noise that use only materials with light and physical properties without a camera, or produce results on the photo-sensitives (films or photographic paper) only with light without any object. These methods do not directly modify the results. Transmission-error also corresponds to the analog-based method despite using the digital camera, because it generates the noise for images due to external or specific internal or physical malfunctions. In glitch art, the noise belongs to the digital one, because it is originated from errors made from the information or digital communication systems. Rosa Menkman defines that glitch art also includes the natural transformation of noise, but most works classified as glitch art intentionally manipulate images and artificially induce noises. These academic confusions raise the necessity of this study to elucidate the difference between intentional transformations and natural ones. This study analyzed <Welcome to Heartbreak>(2009) and <Digital TV Dinner>(1978) as cases of Glitch art that intentionally transforms, and the <TransmissionError> series (2009, 2015, 2018) as examples of the natural transformation. And as a result, it was revealed that their noise generation methods and modes were in contrast. Thus, this study discusses that the glitch art and the transmission-error actually generate noises in completely different ways, although they may visually and superficially show similar results and phenomena. 본 연구의 목적은 노이즈를 활용한 다양한 사진 제작 방식들에서 노이즈 이용의 방법론적 차이를 확인하고, ‘노이즈의 역용(逆用)’의 의도적 수행과 자연적 변형의 차이를 구분하여 노이즈의 수용 양상을 규명하는 것이다. 노이즈를 이용한 사진 기법들로는 가장 잘 알려진 글리치 아트(Glitch art)를 비롯해서 포토그램(Photogram), 루미노그램(Luminogram), 전송오류(Transmission Error) 등이 있다. 포토그램과 루미노그램은 카메라 없이 빛과 물성을 가진 재료만 이용하거나 대상이나 오브제 없이 빛으로만 감광물에 결과물이 산출되는 아날로그 노이즈 방식으로, 작업 과정이나 결과물에 직접적으로변형을 가하지 않는다. 전송오류는 외부 혹은 특정한 내적, 물리적 오동작에 의해 생성된 노이즈를 이미지로 표출하기 때문에 디지털 카메라임에도 불구하도 아날로그 노이즈 방식과 유사하다. 글리치 아트에서 노이즈는 정보나 디지털 통신 시스템으로부터 만들어진 오류에서 발생되기 때문에 디지털 노이즈에 속한다. 로사 멩크만(Rosa Menkman)은 글리치 아트에도 자연적인 변형이 포함된다고 정의하지만, 글리치 아트로 분류되는 작품들은 대부분 이미지를 의도적으로 조작하여 인위적으로 노이즈를유발시키는 방식들이었다. 이와 같은 학술적 논제들은 노이즈를 이용한 사진 제작 방식에서 의도적인변형과 자연적인 변형의 차이를 분명히 하고자 하는 본 연구의 필요성을 제기하였다. 본 연구는 직접적으로 변형을 가하는 글리치 아트의 사례로서 <웰컴 투 하트브레이크>(2009)와 <디지털 TV 디너>(2007)를, 자연적 변형의 사례는 <전송오류> 시리즈(2009, 2015, 2018)를 분석하였다. 그 결과, 글리치와 전송오류의 노이즈 생성과 수용 방식이 서로 대조적임이 드러났다. 이에 따라, 본 연구는직접적으로 이미지에 변형을 가하는 글리치 방식과 이미지 자체의 자연적 변형 과정을 포착하는 전송오류 방식이 시각적으로는 서로 유사한 결과를 보여줄 수 있어도 상이한 방식의 노이즈 수용 양상을보인다는 것을 논구한다.

Reliable Data Transmission Based on Erasure-resilient Code in Wireless Sensor Networks

( Jian-jun Lei ),( Gu-in Kwon ) 한국인터넷정보학회 2010 KSII Transactions on Internet and Information Syst Vol.4 No.1

Emerging applications with high data rates will need to transport bulk data reliably in wireless sensor networks. ARQ (Automatic Repeat request) or Forward Error Correction (FEC) code schemes can be used to provide reliable transmission in a sensor network. However, the naive ARQ approach drops the whole frame, even though there is a bit error in the frame and the FEC at the bit level scheme may require a highly complex method to adjust the amount of FEC redundancy. We propose a bulk data transmission scheme based on erasure-resilient code in this paper to overcome these inefficiencies. The sender fragments bulk data into many small blocks, encodes the blocks with LT codes and packages several such blocks into a frame. The receiver only drops the corrupted blocks (compared to the entire frame) and the original data can be reconstructed if sufficient error-free blocks are received. An incidental benefit is that the frame error rate (FER) becomes irrelevant to frame size (error recovery). A frame can therefore be sufficiently large to provide high utilization of the wireless channel bandwidth without sacrificing the effectiveness of error recovery. The scheme has been implemented as a new data link layer in TinyOS, and evaluated through experiments in a testbed of Zigbex motes. Results show single hop transmission throughput can be improved by at least 20% under typical wireless channel conditions. It also reduces the transmission time of a reasonable range of size files by more than 30%, compared to a frame ARQ scheme. The total number of bytes sent by all nodes in the multi-hop communication is reduced by more than 60% compared to the frame ARQ scheme.

VIBRATIONAL CHARACTERISTICS OF AUTOMOTIVE TRANSMISSION

이형우,박노길,박성환,박문우 한국자동차공학회 2009 International journal of automotive technology Vol.10 No.4

A mathematical model of an automotive transmission is developed, that considers the flexibility of the shafts, bearings, and gear teeth, and gyroscopic effects of geared rotors. The transverse, torsional, and axial motions are strongly coupled due to helical gearing. The excitation forces acting on the automotive transmission are classified into first, second, and third grades, based on the magnitudes of the forces that are determined by the perturbation method. The excitation forces are caused by the mass imbalances among gears, misalignment of shafts, clearance and non-linear deformation of bearings, transmission errors, and the periodic variation of the gear mesh stiffness. A bench test on loading conditions is carried out for the third speed of the automotive transmission. The experimental results of vibration characteristics are compared with those from theoretical analysis. The results show good agreement, i.e., within a tolerance of 3.3%. A mathematical model of an automotive transmission is developed, that considers the flexibility of the shafts, bearings, and gear teeth, and gyroscopic effects of geared rotors. The transverse, torsional, and axial motions are strongly coupled due to helical gearing. The excitation forces acting on the automotive transmission are classified into first, second, and third grades, based on the magnitudes of the forces that are determined by the perturbation method. The excitation forces are caused by the mass imbalances among gears, misalignment of shafts, clearance and non-linear deformation of bearings, transmission errors, and the periodic variation of the gear mesh stiffness. A bench test on loading conditions is carried out for the third speed of the automotive transmission. The experimental results of vibration characteristics are compared with those from theoretical analysis. The results show good agreement, i.e., within a tolerance of 3.3%.

Enhancements of T-REFWA to Mitigate Link Error-Related Degradations in Hybrid Wired/Wireless Networks

Nishiyama, Hiraki,Taleb, Tarik,Nemoto, Yoshiaki,Jamalipour, Abbas,Kato, Nei The Korea Institute of Information and Commucation 2006 Journal of communications and networks Vol.8 No.4

With the on-going wireless access technologies, the Internet has become accessible anytime anywhere. In wireless networks, link errors significantly degrade the performance of the transmission control protocol (TCP). To cope with this issue, this paper improves the recently-proposed terrestrial REFWA (T-REFWA) scheme by adding a new error recovery mechanism to its original design. In the T-REFWA scheme, senders are acknowledged with appropriate sending rates at which an efficient and fair utilization of network resources can be achieved. As the feedback values are computed independently of link errors, senders can keep transmitting data at high rates even in case of link error occurrences. Using this feature, the proposed error recovery mechanism can achieve high throughput in environments with high bit error rates. The throughput is further improved by disabling the exponential back-off algorithm of TCP so that long idle times are avoided in case of link errors. We show through simulations that the proposed method improves TCP performance in high bit error rates. Compared with several TCP variants, the proposed error recovery scheme exhibits higher link utilization and guarantees system fairness for different bit error rates.

자동차용 변속기의 치합전달오차에 의한 진동특성 연구

배명호,박노길 한국소음진동공학회 2001 한국소음진동공학회 논문집 Vol.11 No.8

The gear whine noise of vehicle transmission is directly correlated tilth the gear transmission error of mating gear The object of this study is to build up the synthesized countermeasure for the reduction of gear whine noire of vehicle transmission by developing the program which can be used to analyze and predict the vibrational characteristics caused by gear transmission error of mating gears of vehicle transmission. The developed mathematical models on the elements of transmission, for example, helical gear pairs, bearings and shafts are used and the modeling of the excitation forces are developed by the gear transmission error of mating gear which is defined by the amount of the elastic deformation of gear tooth & shaft and gear profile & lead errors. The mathematical system model of vehicle transmission developed by the substructure synthesis method Is also verified by the experiments.

헬리컬기어의 동적해석을 통한 전달오차 예측

이정석(Jeongseok Lee),윤문영(Moonyoung Yoon),부광석(Kwangsuk Boo),김흥섭(Heungseob Kim) 대한기계학회 2016 大韓機械學會論文集A Vol.40 No.12

기어소음의 근본적인 원인은 전달오차로 인해 발생하게 된다. 전달오차는 기어가 맞물릴 때 발생하는데 크게 정적전달오차와 동적전달오차가 있다. 이러한 오차들은 기어 이빨의 처짐 또는 치면 마찰에 의해 발생하고 이 요인들이 원인이 되어 기어 시스템에 진동이 발생하게 된다. 그리고 이 진동이 기어의 축으로 이동하게 되어 축을 떠받치고 있는 베어링에 전달되고 베어링에 전달된 가진은 최종적으로 기어의 케이싱으로 이동하게 되어 소음을 방출하게 된다. 본 논문에서는 이러한 전달오차에 의해 발생하는 최대 굽힘응력을 가지는 롤각을 찾기 위한 응력해석을 수행되었다. 본 논문에서는 이론적 바탕으로 설계되어 인볼류트 곡선을 가진 기어와 수정된 치형을 가진 기어의 전달오차에 대한 해석을 진행하였다. 또한, 급작스러운 작동이나 큰 백래쉬로 인해 발생하는 충격강도에 대한 영향을 알아보기 위해 유한요소해석을 통해 각각 정적 최대굽힘응력과 동적 최대굽힘응력의 결과를 이용하여 충격인자 값을 예측해 보았다. The fundamental reason for gear noise is transmission error. Transmission error occurs because of STE (static transmission error) and DTE (dynamic transmission error), while a pair of gears is meshing. These errors are generated by the deflection of the teeth and the friction on the surface of the teeth. In addition, the vibration generated by transmission error leads to excited bearings. The bearings support the shafts, and the noise is radiated after exciting the gear casing. The analysis of the contact stress in helical gear tooth flanks indicates that it is due to impact loading, such as the sudden engagement and disengagement of a gear. Stress analysis is performed for different roll positions, in order to determine the most critical roll angle. Dynamic analysis is performed on this critical roll position, in order to evaluate variation in stresses and tooth contact force, with respect to time. In this study, transmission error analysis was implemented on a spur and helical gear with involute geometry and a modified geometry profile. In addition, in order to evaluate the intensity of impact due to sudden engagement and significant backlash, the impact factor was calculated using the finite element analysis results of static and dynamic maximum bending stresses.

Transmission Scheme for Asymmetric MIMO Two-way Relay with Channel Estimation Error

Jinhong Fan,Chaowei Yuan,Ke Xiao 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.7

In this paper, we consider the transmission scheme for asymmetric decode-and-forward (DF) multi-input multi-output (MIMO) two-way relay system with channel estimation error. In order to transmit with asymmetric data rates from the relay to the receivers according to their individual link qualities, we propose a novel transmission scheme for the broadcast phase by employing a priori bit information. The proposed scheme employs multi-antenna and network coding at the relay. The idea is the weaker link receiver exploits a priori bit information in each transmit symbol, so that it only needs to decode on a subset of the transmit symbol constellation. Subject to the same bit error rate constraint, the weaker link receiver can decode at lower signal-to-noise ratio compared to the stronger link. The different signal labeling used for mapping bits to symbols at the relay cause different minimum Euclidean distance, so it is shown to be crucial for the performance at the receivers. Subsequently, we investigate the effect of the channel estimation error on the system performance. Simulations show that the proposed transmission scheme can be applied to practical scenarios with asymmetric channel qualities.