• Journal of the Korean Institute of Intelligent Systems
• /
• v.25 no.2
• /
• pp.186-190
• /
• 2015

Intelligent vehicle plans motion and navigate itself based on the surrounding environment perception. Hence, the precise environment recognition is an essential part of self-driving vehicle. There exist many vulnerable road users (e.g. vehicle, pedestrians) on vehicular driving environment, the vehicle must percept all the dynamic obstacles accurately for safety. In this paper, we propose an multiple vehicle tracking algorithm using microwave radar. Our proposed system includes various special features. First, exceptional radar measurement model for vehicle, concentrated on the corner, is described by mixture density network (MDN), and applied to particle filter weighting. Also, to conquer the curse of dimensionality of particle filter and estimate the time-varying number of multi-target states, reversible jump markov chain monte carlo (RJMCMC) is used to sampling step of the proposed algorithm. The robustness of the proposed algorithm is demonstrated through several computer simulations.

• Journal of Korean Society of Transportation
• /
• v.30 no.1
• /
• pp.59-72
• /
• 2012

In aspects of traffic operation, a climbing lane may cause traffic congestion if the volume of traffic (v/c) grows and the ratio of heavy vehicle increases. Conversely, it would be effective, if the climbing lane is dynamically operated according to changes in traffic flow. However, there are no guideline to effectively control this climbing lane in aspects of traffic operation. In this study, we examine the necessity of flexible traffic operation criteria and its process for dynamic traffic management and also establish and analyze the effect of flexible traffic operation criteria in accordance with traffic properties using an example of climbing lane. We selected the operation criteria (critical travel speed), which decides whether to operate or close the climbing lane when the average travel speed of climbing lane is 50km/h based on VISSM (microscopic traffic simulation) analysis of Nakdong junction towards Masan with the volume of traffic (v/c), ratio of heavy vehicle as the traffic operation parameters. Based on the simulation result in accordance with the volume of traffic by the operation mode of climbing lane, the analysis on the effect of dynamic traffic management of climbing lane showed that the dynamic traffic management provides more convenience compare to the operation and close of climbing lane. Thereby, we proved that the dynamic traffic management of climbing lane is more effective.

• Journal of the Korean Society for Railway
• /
• v.18 no.1
• /
• pp.15-24
• /
• 2015

In magnetic levitation vehicles, the clearance between the magnet and track should be maintained within an allowable range through a feedback control loop. The flexibility of the guideway would introduce additional modes in the overall suspension system, resulting in dynamic interaction between the guideway vibration and the electromagnetic suspension control system. This dynamic interaction can be a serious problem, particularly at very low speeds or standstill, and may cause airgap instability. To optimize the overall system dynamics, an integrated dynamic model including mechanical and electrical parts and a flexible guideway as well as a control loop was developed. With the proposed model, airgap simulations at standstill were performed while varying the control gains, specifically with the aim of understanding the effects of gains of the PID controller on the airgap variation. The findings may be used to achieve a stable levitation controller design.

• Journal of Korean Society of Steel Construction
• /
• v.23 no.2
• /
• pp.199-210
• /
• 2011

The cables in cable-stayed bridges are under high stress and are very sensitive to vibration due to their small section areas compared with other members. Therefore, it is reasonable to evaluate the cable impact factor by taking into account the dynamic effect due to moving-vehicle motion. In this study, the cable impact factors were evaluated via moving-vehicle-load analysis, considering the design parameters, i.e., vehicle weight, cable model, road surface roughness, vehicle speed, longitudinal distance between vehicles. For this purpose, two steel composite cable-stayed bridges with 230- and 540-m main spans were selected. The results of the analysis were then compared with those of the influence line method that is currently being used in design practice. The road surface roughness was randomly generated based on ISO 8608, and the convergence of impact factors according to the number of generated road surfaces was evaluated to improve the reliability of the results. A9-d.o.f. tractor-trailer vehicle was used, and the vehicle motion was derived from Lagrange's equation. 3D finite element models for the selected cable-stayed bridges were constructed with truss elements having equivalent moduli for the cables, and with beam elements for the girders and the pylons. The direct integration method was used for the analysis of the bridge-vehicle interaction, and the analysis was conducted iteratively until the displacement error rate of the bridge was within the specified tolerance. It was acknowledged that the influence line method, which cannot consider the dynamic effect due to moving-vehicle motion, could underestimate the impact factors of the end-cables at the side spans, unlike moving-vehicle-load analysis.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.12
• /
• pp.910-917
• /
• 2018

This paper describes the developments to improve the feeling and safety of the remote control system of unmanned vehicles. Generally, in the case of the remote control systems, a joystick-type device or a simple steering-wheel are used. There are many cases, in which there are operations without considering the feedback to users and driving feel. Recently, as the application area of the unmanned vehicles has been extended, the problems caused by not considering the feedback are emphasized. Therefore, the need for a force feedback-haptic control arises to solve these problems. In this study, the force feedback-haptic control algorithm considering the vehicle parameters is proposed. The vehicle parameters include first the state variables of dynamics, such as the body side-slip angle (${\beta}$) and yawrate (${\gamma}$), and second, the parameters representing the driving situations. Force feedback-haptic control technology consists of the algorithms for general and specific situations, and considers the situation transition process. To verify the algorithms, a simulator was constructed using the vehicle dynamics simulation tool with CAN communication environment. Using the simulator, the feasibility of the algorithms was verified in various scenarios.

• Journal of the Korea Convergence Society
• /
• v.3 no.4
• /
• pp.35-44
• /
• 2012

In this study, a simulation program is developed in order to investigate non steady-state cornering performance of 6WD/6WS special-purpose vehicles. 6WD vehicles are believed to have good performance on off-the-road maneuvering and to have fail-safe capabilities. But the cornering performances of 6WS vehicles are not well understood in the related literature. In this paper, 6WD/6WS vehicles are modeled as a 18 DOF system which includes non-linear vehicle dynamics, tire models, and kinematic effects. Then the vehicle model is constructed into a simulation program using the MATLAB/SIMULINK so that input/output and vehicle parameters can be changed easily with the modulated approach. Cornering performance of the 6WS vehicle is analyzed for brake steering and pivoting, respectively. Simulation results show that cornering performance depends on the middle-wheel steering as well as front/rear wheel steering. In addition, a new 6WS control law is proposed in order to minimize the sideslip angle. Lane change simulation results demonstrate the advantage of 6WS vehicles with the proposed control law.

• Computational Structural Engineering
• /
• v.10 no.3
• /
• pp.233-240
• /
• 1997

The study presents the linear dynamic analysis of multi-girder steel bridges under vehicular movement to examine the performance characteristics due to the various structural and loading conditions. The road surface roughness and bridge-vehicle interactions are considered. The road surface profiles for the approaching roadway and bridge decks are generated from power spectral density functions for different road roughness conditions. A new filtering method using the wheel trace is proposed to obtain the more rational bridge-vehicle interactions from the randomly generated road surface. The possible settlement condition between the bridge deck and approaching roadway is also included. The dynamic responses of various bridges designed according to current design practice are examined, in which important structural parameters(such as span length, girder spacing, etc.) are considered systematically. In addition to the basic loading conditions due to a single truck passing on the bridge, the traffic conditions of multi-truck traveling either consecutively on the same lane or side-by-side on the adjacent lanes are also evaluated.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 1998.06a
• /
• pp.59-66
• /
• 1998

교통정보와 DGPS(Differential GPS) 보정신호의 전송은 ITS(Intelligent Transport System)의 핵심 응용분야인 차량항법시스템(CNS : Car Navigation System)의 동적경로안내(Dynamic Routine Guidance System) 시스템의 핵심적인 요구사항이다. 이 정보들은 서비스 특성상 넓은 지역을 수신지역으로 하고 24시간 연속적으로 전송이 되어야 한다. 즉 주행주인 차량에서 자신의 위치 정확히 파악하기 위한 DGPS 보정신호 및 사고, 교통통제나 체증 등의 교통사항을 항상 수신할 수 있도록 항시 전송이 되어야 한다. FM 방송을 활용하여 이러한 요구사항을 충족시키는 전송채널로 활용될 수 있음을 확인하기 위해 FM 방송과 DARC 방식의 부반송파 시뮬레이터가 제작되었으며 이 시스템의 특성이 연구되었다. 또한 정보데이터를 현용 FM 방송설비를 이용하여 전송하기 위한 방송시스템을 제작하고 서울 및 경기도 지역을 수신지역으로 한 방송수신상태의 측정이 수행되었다. 이 결과들은 FM 부반송이 ITS를 위한 전송채널로서 활용될 수 있다는 것을 보여준다.

• Journal of Korean Society of Transportation
• /
• v.19 no.1
• /
• pp.115-129
• /
• 2001

The purpose of this study is to develop a cycle-free signal timing model for minimizing delays based on Third-generation control concept using Genetic Algorithm. A special feature of this model is its ability to manage delays of turning movements on the cycle basis. The model produces a cycle-free based signal timing(cycles and green times) for each intersection to minimize delays of turning movements on the cycle basis. The performance of cycle-free signal timings was evaluated on normal (v/c = 0.7) and oversaturated (v/c=1.0) conditions. The performance measures are throughput and the number of queued vehicles at the end of green time. The result shows that the cycle free signal timing is superior to the fixed signal timing to manage traffic flows of intersections; (1) the proposed model accomplishes the basic objective of the research, producing cycle free signal timings on the cycle basis, (2) on normal conditions, cycle free signal timings produce less queued vehicles at the end of green time, and (3) on oversaturated conditions, the cycle free signal timing is superior to the fixed signal timing to manage saturated traffic flows of intersections.

• Journal of Auto-vehicle Safety Association
• /
• v.13 no.4
• /
• pp.14-19
• /
• 2021

This paper presents LiDAR static obstacle map based vehicle dynamic state estimation algorithm for urban autonomous driving. In an autonomous driving, state estimation of host vehicle is important for accurate prediction of ego motion and perceived object. Therefore, in a situation in which noise exists in the control input of the vehicle, state estimation using sensor such as LiDAR and vision is required. However, it is difficult to obtain a measurement for the vehicle state because the recognition sensor of autonomous vehicle perceives including a dynamic object. The proposed algorithm consists of two parts. First, a Bayesian rule-based static obstacle map is constructed using continuous LiDAR point cloud input. Second, vehicle odometry during the time interval is calculated by matching the static obstacle map using Normal Distribution Transformation (NDT) method. And the velocity and yaw rate of vehicle are estimated based on the Extended Kalman Filter (EKF) using vehicle odometry as measurement. The proposed algorithm is implemented in the Linux Robot Operating System (ROS) environment, and is verified with data obtained from actual driving on urban roads. The test results show a more robust and accurate dynamic state estimation result when there is a bias in the chassis IMU sensor.