• 한국BIM학회 논문집
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• 제6권2호
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• pp.29-38
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• 2016

Road bridges are deteriorating gradually, and it is forecasted that the number of road bridges aging over 30 years will increase by more than 3 times of the current number. To maintain road bridges in a safe condition, current safety conditions of the bridges must be estimated for repair or reinforcement. However, budget and professional manpower required to perform in-depth inspections of road bridges are limited. This study proposes an estimation model for safety rating of road bridges by analyzing the data from Facility Management System (FMS) and Yearbook of Road Bridges and Tunnel. These data include basic specifications, year of completion, traffic, safety rating, and others. The distribution of safety rating was imbalanced, indicating 91% of road bridges have safety ratings of A or B. To improve classification performance, five safety ratings were integrated into two classes of G (good, A and B) and P (poor ratings under C). This rearrangement was set because facilities with ratings under C are required to be repaired or reinforced to recover their original functionality. 70% of the original data were used as training data, while the other 30% were used for validation. Data of class P in the training data were oversampled by 3 times, and Repeated Incremental Pruning to Produce Error Reduction (RIPPER) algorithm was used to develop the estimation model. The results of estimation model showed overall accuracy of 84.8%, true positive rate of 67.3%, and 29 classification rule. Year of completion was identified as the most critical factor on affecting lower safety ratings of bridges.

• 자동차안전학회지
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• 제3권2호
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• pp.28-33
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• 2011

This paper presents driving path estimation algorithm for adaptive cruise control system and advanced emergency braking system using multi-sensor fusion. Through data collection, yaw rate filtering based road curvature and vision sensor road curvature characteristics are analyzed. Yaw rate filtering based road curvature and vision sensor road curvature are fused into the one curvature by weighting factor which are considering characteristics of each curvature data. The proposed driving path estimation algorithm has been investigated via simulation performed on a vehicle package Carsim and Matlab/Simulink. It has been shown via simulation that the proposed driving path estimation algorithm improves primary target detection rate.

• 대한임베디드공학회논문지
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• 제17권3호
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• pp.149-155
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• 2022

This paper proposes a method for estimating the road surface condition and tilt angle using an inertial measurement unit (IMU) to improve the safety in the use of mobility aids for the elderly. The measurements of the accelerometers of the IMU usually include the accelerations caused by not only the gravitational force but also linear and rotational motions. Thus, the gravitational accelerations are first extracted using several physical constraints and then incorporated into the Kalman filter to estimate the tilt angle. In addition, because the magnitudes of the accelerations produced by the rotational motions (roll and pitch motions) vary with the road surface condition, a criterion based on such accelerations is presented to classify the condition of the road surface. The obtained road surface condition and tilt angle are finally combined to provide the safety information (e.g., safe, warning, and danger) for the user to improve the walking safety. Experiments were carried out and the results showed that the proposed method can provide the condition of the road surface, the tilt of the road surface, and the safety information correctly.

• 한국산업융합학회 논문집
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• 제22권5호
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• pp.575-582
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• 2019

Advanced driving assist system can support safety of driver and passengers which may require vehicle dynamics states as well as road geometry. It is essential to have in real-time estimation of related variables and parameters. Among the road geometry parameters, road slope angle which can not be measured is essential parameter in pose estimation, adaptive cruise control and others on sag road. In this paper, Kalman filter based method for the estimation of the vehicle dynamics and road slope angle using a nonlinear vehicle model is proposed. It uses a combination of Kalman filter as Cascade Extended Kalman Filter. CEKF uses measured vehicle states such as yaw rate, longitudinal/lateral acceleration and velocity. Unknown vehicle parameters such as center of gravity and inertia are obtained by 2 D.O.F lateral model and experimentally. Simulation and Experimental tests conducted with commercialized vehicle dynamics model and real-car.

• 자동차안전학회지
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• 제5권2호
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• pp.17-23
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• 2013

This paper describes an algorithm for Advanced Emergency Braking(AEB) with tire-road friction coefficient estimation. The AEB is a system to avoid a collision or mitigate a collision impact by decelerating the car automatically when forward collision is imminent. Typical AEB system is operated by Time-to-collision(TTC), which considers only relative velocity and clearance from control vehicle to preceding vehicle. AEB operation by TTC has a limit that tire-road friction coefficient is not considered. In this paper, Tire-road friction coefficient is also considered to achieve more safe operation of AEB. Interacting Multiple Model method(IMM) is used for Tire-road friction coefficient estimation. The AEB algorithm consists of friction coefficient estimator and upper level controller and lower level controller. The numerical simulation has been conducted to demonstrate the control performance of the proposed AEB algorithm. The simulation study has been conducted with a closed-loop driver-controller-vehicle system using using MATLAB-Simulink software and CarSim Vehicle model.

• 자동차안전학회지
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• 제12권2호
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• pp.14-20
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• 2020

This paper presents a vehicle mass and road grade estimator for developing an automated bus. To consider the dynamic characteristics of a bus varying with the number of passengers, the longitudinal controller needs the estimation of the vehicle's mass and road grade in real-time and utilizes the information to adjust the control gains. Discrete Kalman filter is applied to estimate the time-varying road grade, and the recursive least squares algorithm is adopted to account for the constant mass estimation. After being implemented in MATLAB/Simulink, the estimators are evaluated with the dynamic model and experimental data of the target bus. The proposed estimators will be applied to complement the algorithm of the longitudinal controller and proceed with algorithm verification.

• 한국도로학회논문집
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• 제7권4호
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• pp.185-202
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• 2005

본 연구에서는 현장 실험 조성의 제약을 극복하기 위해 3차원 가상현실(virtual reality)로 설계중인 도로를 모델링한 후, 피실험자가 Eye camera가 장착된 차량 시뮬레이터 (driving simulator)에 탑승하고 주행하면서 운전자가 행하는 선형변화에 대한 동적 반응 및 운전자의 시각행태에 대한 데이터를 획득하였다 본 실험에 적용된 차량시뮬레이터의 그래픽 모듈은 동역학 해석 모듈에 의해 얻어진 데이터를 기초로 하여 운동재현기와 가상환경의 일치감들 최대로 함으로써 피실험자로 하여금 차량시뮬레이터의 비현실성 및 부작용을 최소화하도록 하였다. 또한, Eye camera는 기존의 여타 장비와는 달리 운전자가 헬멧이나 렌즈 등 어떠한 부착장치도 착용하지 않고 실험할 수 있는 FaceLAB을 사용함으로써 운전자의 자연스러운 시각행태를 아무런 데이터 손실없이 획득하였다. 본 연구에서는 조사된 데이터를 바탕으로 도로 안전성을 평가하기 위해 차량 시뮬레이터, Eye camera방법을 통해 설계시 도로 기하구조 변화에 따라 운전자가 느끼는 안전성의 변화를 파악함으로써 도로 기하구조 조건과 안전성의 상관성을 명확하게 규명하고 이를 통해 운전자가 도로 주행시 편안하고 쾌적한 주행을 보장받을 수 있는 도로를 설계 단계에서부터 평가할 수 있는 방법을 제시하려고 한다.

• 전자공학회논문지
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• 제51권9호
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• pp.208-214
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• 2014

차선유지 제어시스템, 적응식순항 제어시스템과 같은 첨단운전 지원시스템은 기본적으로 차량의 거동 정보를 기반으로 구동되지만, 최근 도로의 기하학적 정보를 추가적으로 활용하는 연구가 활발히 진행되고 있다. 특히, 도로의 종단경사는 차량의 가감속 제어 및 항법알고리즘 구현에 있어 필수적인 정보로서 DGPS-RTK와 같은 고가의 장비로 직접 측정하는 방법과 디지털 맵에 저장된 속성정보를 활용하는 방식이 제안되고 있으나, 상용화 관점에서는 아직 많은 문제점이 존재한다. 따라서, 본 논문에서는 추가 센서의 장착없이 연속형 확장칼만필터를 활용하여 차량의 동특성과 도로종단경사를 효율적으로 추정하는 알고리즘을 제안한다. 도로종단경사를 포함하는 3자유도 차량동역학 모델과 차량의 내부 네트워크롤 통해 수집할 수 있는 차량의 상태정보를 기반으로 확장칼만필터를 설계하여 차량의 동특성과 도로종단경사를 추정한다. 제안된 알고리즘은 시뮬레이션과 실차실험을 통해 그 성능을 검증하였다.

• 한국자동차공학회논문집
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• 제24권3호
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• pp.310-318
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• 2016

The demands for vehicle safety systems such as ABS and ESC have been increased. Accurate vehicle state estimation is required to realized the abovementioned systems and tire-friction coefficient is crucial information. Estimation of lateral tire-road friction coefficient using pneumatic trail information is mainly dealt in this paper. Pneumatic trail shows unique characteristics according to the wheel side slip angle and these property is highly sensitive to vehicle lateral motion. The proposed algorithm minimizes the use of conventional tire models such as magic formula, brushed tire model and Dugoff tire model. The pure side slip maneuver, which means no longitudinal dynamics, is assumed to achieve the ultimate goal of this paper. A simulation verification using Carsim and Simulink is performed and the results show the feasibility of the proposed algorithms.

• 한국도로학회:학술대회논문집
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• 한국도로학회 2008년도 추계학술대회 논문집
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• pp.307-320
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• 2008