Application of Compensation Method of Motion Analysis Error Using Displacement Dependency between Anatomical Landmarks and Skin Markers Due to Soft Tissue Artifact

류태범(Taebeum Ryu) 한국산업경영시스템학회 2012 한국산업경영시스템학회지 Vol.35 No.4

Of many approaches to reduce motion analysis errors, the compensation method of anatomical landmarks estimates the position of anatomical landmarks during motion. The method models the position of anatomical landmarks with joint angle or skin marker displacement using the data of the so-called dynamic calibration in which anatomical landmark positions are calibrated in ad hoc motions. Then the anatomical landmark positions are calibrated in target motions using the model. This study applies the compensation methods with joint angle and skin marker displacement to three lower extremity motions (walking, sit-to-stand/stand-to-sit, and step up/down) in ten healthy males and compares their performance. To compare the performance of the methods, two sets of kinematic variables were calculated using different two marker clusters, and the difference was obtained. Results showed that the compensation method with skin marker displacement had less differences by 30~60% compared to without compensation. And, it had significantly less difference in some kinematic variables (7 of 18) by 25~40% compared to the compensation method with joint angle. This study supports that compensation with skin marker displacement reduced the motion analysis STA errors more reliably than with joint angle in lower extremity motion analysis.

연조직 변형에 의한 해부학적 지표와 피부마커의 변위 상관성을 이용한 동작분석 오차 보정 방법의 적용

유태범 한국산업경영시스템학회 2012 한국산업경영시스템학회지 Vol.35 No.4

Of many approaches to reduce motion analysis errors, the compensation method of anatomical landmarks estimates the position of anatomical landmarks during motion. The method models the position of anatomical landmarks with joint angle or skin marker displacement using the data of the so-called dynamic calibration in which anatomical landmark positions are calibrated in ad hoc motions. Then the anatomical landmark positions are calibrated in target motions using the model. This study applies the compensation methods with joint angle and skin marker displacement to three lower extremity motions (walking, sit-to-stand/stand-to-sit, and step up/down) in ten healthy males and compares their performance. To compare the performance of the methods,two sets of kinematic variables were calculated using different two marker clusters, and the difference was obtained. Results showed that the compensation method with skin marker displacement had less differences by 30~60% compared to without compensation. And, it had significantly less difference in some kinematic variables (7 of 18) by 25~40% compared to the compensation method with joint angle. This study supports that compensation with skin marker displacement reduced the motion analysis STA errors more reliably than with joint angle in lower extremity motion analysis.

Motion Compensation for Ultrasound Thermal Imaging Using Motion-Mapped Reference Model: An <i>in vivo</i> Mouse Study

Seo, Joonho,Kim, Sun Kwon,Kim, Young-sun,Choi, Kiwan,Kong, Dong Geon,Bang, Won-Chul IEEE 2014 IEEE Transactions on Biomedical Engineering Vol.61 No.11

<P>Ultrasound (US)-based thermal imaging is very sensitive to tissue motion, which is a major obstacle to apply US temperature monitoring to noninvasive thermal therapies of in vivo subjects. In this study, we aim to develop a motion compensation method for stable US thermal imaging in in vivo subjects. Based on the assumption that the major tissue motion is approximately periodic caused by respiration, we propose a motion compensation method for change in backscattered energy (CBE) with multiple reference frames. Among the reference frames, the most similar reference to the current frame is selected to subtract the respiratory-induced motions. Since exhaustive reference searching in all stored reference frames can impede real-time thermal imaging, we improve the reference searching by using a motion-mapped reference model. We tested our method in six tumor-bearing mice with high intensity focused ultrasound (HIFU) sonication in the tumor volume until the temperature had increased by 7°C. The proposed motion compensation was evaluated by root-meansquare-error (RMSE) analysis between the estimated temperature by CBE and the measured temperature by thermocouple. As a result, the mean±SD RMSE in the heating range was 1.1 ± 0.1°C with the proposed method, while the corresponding result without motion compensation was 4.3 ± 2.6°C. In addition, with the idea of motion-mapped reference frame, total processing time to produce a frame of thermal image was reduced in comparison with the exhaustive reference searching, which enabled the motioncompensated thermal imaging in 15 frames per second with 150 reference frames under 50% HIFU duty ratio.</P>

Hardware Design of 3-Axis Motion Platform with Load Compensation Mechanism

박정우(Jeong Woo Park),김효곤(Hyo Gon Kim),최영호(Young Ho Choi),박성호(Sung Ho Park),이효준(Hyo Jun Lee) Korean Society for Precision Engineering 2020 한국정밀공학회지 Vol.37 No.6

The motion platform supports the trainee in experiencing a sense of reality in virtual space by performing a motion on the available degrees of freedom for a motion that mimics a specific motion in connection with a virtual reality content or a simulator. The required specification of the motor and driver of motion platform is determined by the target specification for the upward motion of the motion plate. The reason is that the weight of the upper plate always applies gravity in the direction of the downward motion. As a result, the downward motion has an excessive specification compared to the upward motion specification, resulting in an unbalanced motion specification. Additionally, a problem may occur in which a volume increases from the application of a high specification driving unit. In this paper, the motion platform was designed capable of three-axis motion in roll, pitch, and gravity directions using a compression spring to apply a load compensation mechanism. Based on the design results, the specifications of the compression spring for motion platform to satisfy the operating specifications do not excessively move the upward and downward direction derived by the analysis.

Robust Motion Compensated Frame Interpolation Using Weight-Overlapped Block Motion Compensation with Variable Block Sizes to Reduce LCD Motion Blurs

이지찬,이대호,최진혁 한국광학회 2015 Current Optics and Photonics Vol.19 No.5

Liquid crystal displays (LCDs) have slow responses, so motion blurs are often perceived in fast movingscenes. To reduce this motion blur, we propose a novel method of robust motion compensated frameinterpolation (MCFI) based on bidirectional motion estimation (BME) and weight-overlapped block motioncompensation (WOBMC) with variable block sizes. In most MCFI methods, a static block size is used,so some block artefacts and motion blurs are observed. However, the proposed method adjusts motionblock sizes and search ranges by comparing matching scores, so the precise motion vectors can be estimatedin accordance with motions. In the MCFI, overlapping ranges for WOBMC are also determined by adjustedblock sizes, so the accurate MCFI can be performed. In the experimental results, the proposed methodstrongly reduced motion blurs arisen from large motions, and yielded interpolated images with high visualperformance and peak signal-to-noise ratio (PSNR)

SAR(Synthetic Aperture Radar)시스템 요동보상기법 연구

강은균,나극환,Kang, Eun-Kyun,Ra, Keuk-Hwan 대한전자공학회 2013 전자공학회논문지 Vol.49 No.11

본 논문에서는 Synthetic Aperture Radar 시스템 요동보상기법을 통해 영상을 형성하는 방법을 컴퓨터 시뮬레이션으로 실현하였다. 거리압축과정, 보상과정, 방위압축과정 및 잡음제거과정 등 요동보상 기법을 단계별로 실행하여 영상데이터를 형성하였다. 거리압축과정은 SAR 생데이터를 주파수영역으로 변환하고 변환된 데이터와 주파수영역의 거리참조함수를 상관시킨 후 결과를 시간영역으로 역변환 시키는 과정이다. 보상과정은 SAR를 탑재한 비행체의 요동을 보상하는 과정과 영상형성 방법상의 화질 저하요인을 제거하는 과정으로 분류하여 수행하였다. 비행체의 요동을 보상하는 과정은 렌지 게이트의 개폐시각을 기준으로 위상각을 보정하는 단계 및 빔내의 각 렌지 게이트에 대한 도플러 주파수를 계산하여 수신 데이터의 지상좌표를 결정하는 단계로 분류하여 수행하였다. 영상형성 방법상의 화질저하 요인을 보상하는 과정은 거리이동 효과 및 몽롱화 현상의 보상기준에 따라 보상의 정도 및 보상 유무가 결정되고 필요한 경우에만 보상과정이 수행된다. 방위압축과정은 보상과정이 완료된 데이터를 다시 주파수영역으로 변환하여 방위참조함수와 상관시킨 후 결과를 시간영역으로 역변환 시키는 과정으로 SAR의 영상데이터를 형성한다. 이렇게 형성된 영상데이터는 잡음과 신호가 혼용된 상태이므로 임계값을 적용하여 잡음과 신호를 분리한다. In this paper, the image formation by the motion compensation technique for Synthetic Aperture Radar system(SAR) were realized through the computer simulation. The motion compensation technique performed image data with the range compression, the compensation procedure, the azimuth compensation and the noise elimination procedure. The range compression procedure transform the SAR raw data into the frequency domain and correlate with the range reference function and then inversely transform into the time domain. The compensation procedure contain the aircraft fluctuations compensation and the radar image degrading effect elimination procedure which was caused by image formation algorithm itself. The aircraft fluctuations compensation procedure perform the first stage which correct the phase angle and the second stage which calculate the Doppler frequency and determine the coordinate of the received signal. The radar image degrading effect elimination procedure also perform range migration compensation and the image defocussing effect compensation. The azimuth compression procedure transform the compensation data to the frequency domain and correlate with the azimuth reference function. The azimuth correlated data are inversely transformed to the time domain which is called SAR image data. When the above procedure were completed, the image data contains the received signals mixed with noise. The threshold technique was applied to elimination the noise from the mixed image data.

Motion-Compensated Frame Interpolation Using a Parabolic Motion Model and Adaptive Motion Vector Selection

최강선,Min-Chul Hwang 한국전자통신연구원 2011 ETRI Journal Vol.33 No.1

We propose a motion-compensated frame interpolation method in which an accurate backward/forward motion vector pair (MVP) is estimated based on a parabolic motion model. A reliability measure for an MVP is also proposed to select the most reliable MVP for each interpolated block. The possibility of deformation of bidirectional corresponding blocks is estimated from the selected MVP. Then, each interpolated block is produced by combining corresponding blocks with the weights based on the possibility of deformation. Experimental results show that the proposed method improves PSNR performance by up to 2.8 dB as compared to conventional methods and achieves higher visual quality without annoying blockiness artifacts.

Ego-Motion 보정기법을 적용한 쿼드로터의 화재 감지 알고리즘

이영완(Young-Wan Lee),김진황(Jin-Hwang Kim),오정주(Jeong-Ju Oh),김학일(Hakil Kim) 제어로봇시스템학회 2015 제어·로봇·시스템학회 논문지 Vol.21 No.1

A conventional fire detection has been developed based on images captured from a fixed camera. However, It is difficult to apply current algorithms to a flying Quad-rotor to detect fire. To solve this problem, we propose that the fire detection algorithm can be modified for Quad-rotor using Ego-motion compensation. The proposed fire detection algorithm consists of color detection, motion detection, and fire determination using a randomness test. Color detection and randomness test are adapted similarly from an existing algorithm. However, Ego-motion compensation is adapted on motion detection for compensating the degree of Quad-rotor"s motion using Planar Projective Transformation based on Optical Flow, RANSAC Algorithm, and Homography. By adapting Ego-motion compensation on the motion detection step, it has been proven that the proposed algorithm has been able to detect fires 83% of the time in hovering mode.

IGRT를 위한 비침습적인 호흡에 의한 장기 움직임 실시간 추적시스템

김윤종,윤의중,Kim, Yoon-Jong,Yoon, Uei-Joong 대한의용생체공학회 2007 의공학회지 Vol.28 No.5

A non-invasive respiratory gated radiotherapy system like those based on external anatomic motion gives better comfortableness to patients than invasive system on treatment. However, higher correlation between the external and internal anatomic motion is required to increase the effectiveness of non-invasive respiratory gated radiotherapy. Both of invasive and non-invasive methods need to track the internal anatomy with the higher precision and rapid response. Especially, the non-invasive method has more difficulty to track the target position successively because of using only image processing. So we developed the system to track the motion for a non-invasive respiratory gated system to accurately find the dynamic position of internal structures such as the diaphragm and tumor. The respiratory organ motion tracking apparatus consists of an image capture board, a fluoroscopy system and a processing computer. After the image board grabs the motion of internal anatomy through the fluoroscopy system, the computer acquires the organ motion tracking data by image processing without any additional physical markers. The patients breathe freely without any forced breath control and coaching, when this experiment was performed. The developed pattern-recognition software could extract the target motion signal in real-time from the acquired fluoroscopic images. The range of mean deviations between the real and acquired target positions was measured for some sample structures in an anatomical model phantom. The mean and max deviation between the real and acquired positions were less than 1mm and 2mm respectively with the standardized movement using a moving stage and an anatomical model phantom. Under the real human body, the mean and maximum distance of the peak to trough was measured 23.5mm and 55.1mm respectively for 13 patients' diaphragm motion. The acquired respiration profile showed that human expiration period was longer than the inspiration period. The above results could be applied to respiratory-gated radiotherapy.

LuGre Model-Based Neural Network Fiction Compensator in a Linear Motor Stage

Rong-Hwang Horng,Li Ren Lin,An-Chen Lee 한국정밀공학회 2006 International Journal of Precision Engineering and Vol.7 No.2

This paper proposes a LuGre Model-Based Neural Network (MBNN) friction compensation algorithm for a linear motor stage. For matching the friction phenomena in both the motion-start region and the motion-reverse region, the LuGre dynamic model is employed into the proposed compensation algorithm. After training of the model-based neural network is completed, the estimated friction for compensation is obtained. From the obtained result we find hat the new structure gains advantage over the non-friction compensation system on the performance of the compensator in both regions. The proposed compensator is evaluated and compared experimentally with an uncompensated system on a microcomputer controlled linear motor tracking system in the final section of the paper. The experimental results show the improvement on the maximum velocity error and the root mean square tracking error in the motion-start region ranges from 34% to 53% and from 53% to 75% respectively, and in the motion-reverse region from 48% to 65% and from 79% to 90% respectively.