• 제어로봇시스템학회논문지
• /
• 제14권6호
• /
• pp.595-602
• /
• 2008

In this paper, performance of the initial alignment for INS whose attitude is not leveled is investigated. Observability of the initial alignment filter is analyzed and estimation errors of the estimated state variables are derived. First, the observability is analyzed using the rank test of observability matrix and the normalized error covariance of the Kalman filter based on the 10-state model. In result, it can be seen that the accelerometer biases on horizontal axes are unobservable. Second, the steady-state estimation errors of the state variables are derived using the observability equation. It is verified that the estimates of the state variables have errors due to the unobservable state variables and the non-leveling tilt angles of a vehicle containing the INS. Especially, this paper shows that the larger the tilt angles of the vehicle are, the larger the estimation errors corresponding to the sensor biases are. Finally, it is shown that the performance of the 8-state model excepting the accelerometer biases on horizontal axes is better than that of the 10-state model in the initial alignment by simulation.

• International Journal of Aeronautical and Space Sciences
• /
• 제18권3호
• /
• pp.565-573
• /
• 2017

This paper presents a multistage in-flight alignment (MIFA) method for a strapdown inertial navigation system (SDINS) suitable for moving vehicles with no initial attitude references. A SDINS mounted on a moving vehicle frequently loses attitude information for many reasons, and it makes solving navigation equations impossible because the true motion is coupled with an undefined vehicle attitude. To determine the attitude in such a situation, MIFA consists of three stages: a coarse horizontal attitude, coarse heading, and fine attitude with adaptive Kalman navigation filter (AKNF) in order. In the coarse horizontal alignment, the pitch and roll are coarsely estimated from the second order damping loop with an input of acceleration differences between the SDINS and GPS. To enhance estimation accuracy, the acceleration is smoothed by a scalar filter to reflect the true dynamics of a vehicle, and the effects of the scalar filter gains are analyzed. Then the coarse heading is determined from the GPS tracking angle and yaw increment of the SDINS. The attitude from these two stages is fed back to the initial values of the AKNF. To reduce the estimated bias errors of inertial sensors, special emphasis is given to the timing synchronization effects for the measurement of AKNF. With various real flight tests using an UH60 helicopter, it is proved that MIFA provides a dramatic position error improvement compared to the conventional gyro compass alignment.

• The Journal of Korean Physical Therapy
• /
• 제33권2호
• /
• pp.76-83
• /
• 2021

Purpose: This study examined the effects of applying the Pilates reformer exercise to 17 adult women on the alignment of the standing posture. Methods: The subjects performed a Pilates reformer exercise for 60 minutes a day, three times a week, for a total of eight weeks. The Pilates reformer exercise consisted of five types: 1) lower and lift, 2) hundred, 3) plow, 4) airplane, and 5) twist. The standing posture alignment in the sagittal and frontal planes was measured using exbody 9100MOMI musculoskeletal analysis equipment. Results: A comparison of before and after the exercise using paired t-test revealed a significant decrease in the difference between the horizontal inclination and the vertical height that approached zero after the intervention in the frontal plane of anterior and posterior standing postures (p<0.05), and the lateral standing posture in the sagittal plane. In addition, the difference between the horizontal inclination and the vertical height decreased and approached zero after the intervention (p<0.05). Conclusion: The Pilates reformer exercise had a positive effect on the alignment of the standing posture.

• 한국도로학회논문집
• /
• 제13권2호
• /
• pp.175-185
• /
• 2011

도로기하구조정보는 도로의 안전성평가 및 도로의 유지관리를 위한 필수적인 요소이다. 본 연구에서는 GPS(Global Positioning System)/INS(Inertial Navigation System)센서가 탑재된 조사차량을 이용하여 기하구조정보를 수집하였으며, 수집된 차량의 자세정보 중 평면선형과 관련된 Roll, Heading 자료를 이용하여 직선, 원곡선, 완화곡선을 구분하는 알고리즘을 개발하였다. 본 연구에서는 평면선형 인식 이전에 전처리 과정으로 이동평균법을 통하여 자료를 평활화함으로써 원시자료의 이상치를 제거하여 평면선형 인식의 신뢰성을 제고하였다. 유전알고리즘(GA, Genetic Algorithm)을 이용하여 분류정확도(CCR, Correct Classification Rate)를 최대로 하는 알고리즘 파라미터를 설정한 결과 100%의 분류정확도를 보였다. 설정된 파라미터를 이용하여 고속도로와 국도 주행자료를 이용하여 알고리즘을 평가한 결과 90.48%와 88.24%의 분류정확도를 보여, 제안된 평면선형인식 알고리즘은 현장에서 적용 시 높은 신뢰도를 가지는 정보를 제공 가능한 것으로 분석되었다. 본 연구에서 개발한 평면선형인식 알고리즘은 조사차량에 GPS/INS센서의 소프트웨어로 탑재되어 도로 및 교통기술자에게 도로기하구조정보를 보다 용이하게 수집하고 분석할 수 있는 환경을 제공하는데 기여할 것으로 기대된다.

• 대한교통학회:학술대회논문집
• /
• 대한교통학회 1997년도 제32회 학술발표회
• /
• pp.33-69
• /
• 1997

This study was conducted to develop a methodology to predict utility pole accident rates and to evaluate cost-effectiveness for safety improvement for utility pole accidents. The utility pole accident rate prediction model was based on the encroachment rate approach introduced in the Transportation Research Board Special Report 214. The utility pole accident rate on a section of highway depends on the roadside encroachment rate and the lateral extent of encroachment. The encroachment rate is influenced by the horizontal and vertical alignment of the highway as well as traffic volume and mean speed. The lateral extent of encroachment is affected by the horizontal and vertical alignment, the mean speed and the roadside slope. An analytical method to generate the probability distribution function for the lateral extent of encroachment was developed for six kinds of encroachment types by the horizontal alignment and encroachment direction. The encroachment rate was calibrated with the information on highway and roadside conditions and the utility pole accident records collected on the sections of 55mph speed limit of the State Trunk Highway 12 in Wisconsin. The encroachment rate on a tangent segment was calibrated as a function of traffic volume with the actual average utility pole accident rates by traffic volume strategies. The adjustment factors for horizontal and vertical alignment were then derived by comparing the actual average utility pole accident rates to the estimations from the model calibrated for tangent and level sections. A computerized benefit-cost analysis procedure was then developed as a means of evaluating alternative countermeasures. The program calculates the benefit-cost ratio and the percent of reduction of utility pole accidents resulting from the implementation of a safety improvement. This program can be used to develop safety improvement: alternatives for utility pole accidents when a predetermined performance level is specified.

• 대한교통학회:학술대회논문집
• /
• 대한교통학회 1997년도 제32회 학술발표회
• /
• pp.35-72
• /
• 1997

This study was conducted to develop a methodology to predict utility pole accident rates and to evaluate cost-effectiveness for safety improvement for utility pole accidents. The utility pole accident rate prediction model was based on the encroachment rate approach introduced in the Transportation Research Board special Report 214. The utility pole accident rate on a section of highway depends on the roadside encroachment rate and the lateral extent of encroachment. The encroachment rate is influenced by the horizontal and vertical alignment of the highway as well as traffic volume and mean speed. The lateral extent of encroachment is affected by the horizontal and vertical alignment, the mean speed and the roadside slope. An analytical method to generate the probability distribution function for the lateral extent of encroachment was developed for six kinds of encroachment types by the horizontal alignment and encroachment direction. The encroachment rate was calibrated with the information on highway and roadside conditions and the utility pole accident records collected on the sections of 55mph speed limit of the State Trunk Highway 12 in Wisconsin. The encroachment rate on tangent segment was calibrated as a function of traffic volume with the actual average utility pole accident rates by traffic volume strategies. The adjustment factors for horizontal and vertical alignment were when derived by comparing the actual average utility pole accident rates to the estimations from the model calibrated for tangent and level sections. A computerized benefit-cost analysis procedure was then developed as a means of evaluating alternative countermeasures. The program calculates the benefit-cost ratio and the percent of reduction of utility pole accidents resulting from the implementation of a safety improvement. This program can be used to develop safety improvement alternatives for utility pole accidents when a predetermined performance level is specified.

• 한국공작기계학회논문집
• /
• 제12권6호
• /
• pp.64-70
• /
• 2003

A measurement of spacecraft alignment is an important process of spacecraft assembly, integration and test because it is necessary that a ground station controls the precise positions of on-orbit spacecraft by using the alignment data of attitude orbit control sensors(AOCS) on spacecraft. In addition, accuracy of spacecraft alignment requirement is about $0.1^{\circ}$~$0.7^{\circ}$. The spacecraft alignment is measured by autocollimation of theodolite. This paper describes the measurement principle and method of spacecraft alignment. The result shows that all of the AOCS on the spacecraft are aligned within the tolerance required through the alignment measurement.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.537-540
• /
• 2005

The attitude control, sensors and camera installed on the spacecraft should be located according to the system alignment requirement. The alignment measurement requirement accuracy for the sensors should be below $\pm$0.1. Therefore, Alignment Measurement System which is combined theodolite, Rotating table and digital inclinometer etc., should be used. As the measurement accuracy is required very precise, the appropriate measurement procedure and alignment angle measurement, calculation and shimming work should is accomplished. Consequently, this paper is accomplished the works to align the measurement requirement accuracy throughout alignment measurement and shimming work of installed module and sensor

• Earthquakes and Structures
• /
• 제16권6호
• /
• pp.715-726
• /
• 2019

Several municipal seismic vulnerability investigations have been identified pounding of adjacent structures as one of the main hazards due to the constrained separation distance between adjacent buildings. Consequently, an assessment of the seismic pounding risk of buildings is superficial in future adjustment of design code provisions for buildings. The seismic lateral oscillation of adjacent buildings with eccentric alignment is partly restrained, and therefore a torsional response demand is induced in the building under earthquake excitation due to eccentric pounding. In this paper, the influence of the eccentric seismic pounding on the design demands for adjacent symmetric buildings with eccentric alignment is presented. A mathematical simulation is formulated to evaluate the eccentric pounding effects on the seismic design demands of adjacent buildings, where the seismic response analysis of adjacent buildings in series during collisions is investigated for various design parameters that include number of stories; in-plan alignment configurations, and then compared with that for no-pounding case. According to the herein outcomes, the effects of seismic pounding severity is mainly depending on characteristics of vibrations of the adjacent buildings and on the characteristics of input ground motions as well. The position of the building wherever exterior or interior alignment also, influences the seismic pounding severity as the effect of exposed direction from one or two sides. The response of acceleration and the shear force demands appear to be greater in case of adjacent buildings as seismic pounding at different levels of stories, than that in case of no-pounding buildings. The results confirm that torsional oscillations due to eccentric pounding play a significant role in the overall pounding-involved response of symmetric buildings under earthquake excitation due to horizontal eccentric alignment.

• 한국항행학회논문지
• /
• 제22권6호
• /
• pp.500-506
• /
• 2018

본 논문에서는 유도탄의 정확한 자세를 알기 위해 주 관성항법장치와 유도탄 내부 관성항법장치를 이용하는 one-shot 정렬에 대해 고려하였다. One-shot정렬을 수행하기 위해서는 주 관성항법장치와 부 관성항법장치 사이의 비정렬각을 구해야 되는데, 장입유도탄과 부 관성항법장치 사이의 비정렬각을 구하여 보상하면 된다. 비정렬각은 장입유도탄의 롤 회전을 이용하여 산출되며, 장입유도탄을 회전하기 위한 정렬용 치구, 장입유도탄의 수평 상태를 측정하기 위한 수평각도계와 인터페이스 구조물이 제작되었다. TAS(tilt angle save) 점검 결과, 비정렬각 ${\alpha}$, ${\beta}$, ${\gamma}$ 값이 정상 범위이며 이 값을 보상하여 one-shot 정렬을 수행할 수 있다.