• 제어로봇시스템학회논문지
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• 제17권6호
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• pp.513-520
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• 2011

This paper presents the motion planning of robotic vehicles for the path tracking and the obstacle avoidance. To follow the given path, the vehicle moves through the turning radius obtained through the pure pursuit method, which is a geometric path tracking method. In this paper, we assume that the vehicle is equipped with a 2D laser scanner, allowing it to avoid obstacles within its sensing range. The turning radius for avoiding the obstacle, which is inversely proportional to the virtual force, is then calculated. Therefore, these two kinds of the turning radius are used to generate the steering angle for the front wheel of the vehicle. And the vehicle reduces the velocity when it meets the obstacle or the large steering angle using the potentials of obstacle points and the steering angle. Thus the motion planning of the vehicle is done by planning the steering angle for the front wheels and the velocity. Finally, the performance of the proposed method is tested through simulation.

• 농업과학연구
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• 제50권4호
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• pp.773-784
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• 2023

In this study, we developed a dynamic model and steering controller model for an autonomous tractor and evaluated their performance. The traction force was measured using a 6-component load cell, and the rotational speed of the wheels was monitored using proximity sensors installed on the axles. Torque sensors were employed to measure the axle torque. The PI (proportional integral) controller's coefficients were determined using the trial-error method. The coefficient of the P varied in the range of 0.1 - 0.5 and the I coefficient was determined in 3 increments of 0.01, 0.05, and 0.1. To validate the simulation model, we conducted RMS (root mean square) comparisons between the measured data of axle torque and the simulation results. The performance of the steering controller model was evaluated by analyzing the damping ratio calculated with the first and second overshoots. The average front and rear axle torque ranged from 3.29 - 3.44 and 6.98 - 7.41 kNm, respectively. The average rotational speed of the wheel ranged from 29.21 - 30.55 rpm at the front, and from 21.46 - 21.63 rpm at the rear. The steering controller model exhibited the most stable control performance when the coefficients of P and I were set at 0.5 and 0.01, respectively. The RMS analysis of the axle torque results indicated that the left and right wheel errors were approximately 1.52% and 2.61% (at front) and 7.45% and 7.28% (at rear), respectively.

• 한국ITS학회 논문지
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• 제7권6호
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• pp.133-139
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• 2008

본 논문에서는 플라스틱 광섬유 센서가 운전자의 졸음 방지용 센서로서 응용 가능한 지에 관하여 논의된다. 졸음방지용 플라스틱 광섬유 센서는 광섬유의 구부림이 잘 유도될 수 있도록 소프트한 물질로 덮개를 씌운 핸들에 플라스틱 광섬유가 감겨져 여는 구조로 되어져 있다. 운전자가 핸들을 잡을 때 운전자가 핸들에 힘을 가하게 되고 이 힘이 플라스틱 광섬유의 구부림을 유도하여 플라스틱 광섬유 내부를 진행하는 빛의 양을 감소시킨다. 실험 결과로부터 핸들에 가해지는 힘이 크면 클수록 검출되는 광량이 적어짐을 보여주어 졸음 방지용 센서로서의 사용할 수 있음을 검증해 보인다.

• 대한임베디드공학회논문지
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• 제15권6호
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• pp.269-279
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• 2020

This paper presents the design and implementation of embedded systems and autonomous path generation for autonomous speed sprayer. Autonomous Orchard Systems can be divided into embedded controller and path generation module. Embedded controller receives analog sensor data, on/off switch data and control linear actuator, break, clutch and steering module. In path generation part, we get 3D cloud point using Velodyne VLP16 LIDAR sensor and process the point cloud to generate maps, do localization, generate driving path. Then, it finally generates velocity and rotation angle in real time, and sends the data to embedded controller. Embedded controller controls steering wheel based on the received data. The developed autonomous speed sprayer is verified in test-bed with apple tree-shaped artworks.

• 대한기계학회논문집A
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• 제37권6호
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• pp.731-738
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• 2013

본 논문은 6 륜 독립구동/독립조향 차량의 독립 스티어-바이-와이어 장치의 고장 안전 주행 제어방법을 제시하였다. 조향부 고장 휠의 횡방향 타이어 힘이 차량 선회 운동에 저항력으로 작용할 수 있으므로, 이를 줄이기 위하여 본 고장 안전 주행 제어 알고리즘은 조향부 고장 휠에 높은 슬립률이 발생하도록 토크 입력을 가한다. 고슬립으로 인한 조향부 고장 휠의 종방향 타이어 힘 증가를 고려하기 위하여 종방향 타이어 힘을 추정하여 고장나지 않은 휠의 구동력 최적 분배에 구속 조건에 포함시킨다. 개루프 조향 및 폐루프 조향 시뮬레이션 결과 조향부 고장이 발생한 차량의 주행시 고장을 고려하지 않은 최적 구동력 분배 제어에 비하여 본 알고리즘 적용시 차량의 주행 성능이 보정됨을 확인하였다.

• 제어로봇시스템학회논문지
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• 제17권6호
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• pp.558-565
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• 2011

Various robot platforms have been designed and developed to perform given tasks in a hazardous environment for surveillance, reconnaissance, search and rescue, etc. We considered a terrain-adaptive and transformable hybrid robot platform that is equipped with rapid navigation capability on flat floors and good performance in overcoming stairs or obstacles. The navigation mode transition is determined and implemented by adaptive driving mode control of the mobile robot. In order to maximize the usability of wheel-track hybrid robot platform, we propose a terrain-adaptive and user-friendly remote controller and verify the efficiency and performance through its navigation performance experiments in real and test-bed environments.

• 한국자동차공학회논문집
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• 제14권6호
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• pp.34-42
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• 2006

As many systems depend on electronics, concern for fault tolerance is growing rapidly. For example, a car with its steering controlled by electronics and no mechanical linkage from steering wheel to front tires(steer-by-wire) should be fault tolerant because a failure can come without any warning and its effect is devastating. In order to make system fault tolerant, there has been a body of research mainly from aerospace field. This paper presents the structure of predictive smoothing voter that can filter out most erroneous values and noise. In addition, several numerical simulation results are given where the predictive smoothing voter outperforms well-known average and median voters.

• 한국자동차공학회논문집
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• 제6권4호
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• pp.160-165
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• 1998

In this paper, We discuss the directional stability of a Mini-bus with varying suspension design parameters. We analyzed the vehicle behavior during the cornering in a transient steering condition. We made a vehicle model by use of DADS, which is dynamic analysis software, in order to carry out many cases of simulation with varying design parameters. The effect of toe-geometry change to vehicle stability is evaluated by computer simulation and the actual test. In order to reduce the under steer characteristics of a mini-bus, the amount of toe geometry change should be less than current value.

• International Journal of Control, Automation, and Systems
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• 제6권1호
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• pp.126-134
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• 2008

As many systems depend on electronics, concern for fault tolerance is growing rapidly. For example, a car with its steering controlled by electronics and no mechanical linkage from steering wheel to front tires (steer-by-wire) should be fault tolerant because a failure can come without any warning and its effect is devastating. In order to make system fault tolerant, there has been a body of research mainly from aerospace field. This paper presents the structure of predictive hybrid redundancy that can remove most erroneous values. In addition, several numerical simulation results are given where the predictive hybrid redundancy outperforms wellknown average and median voters.

• 오토저널
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• 제9권6호
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• pp.37-45
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• 1987

최근의 경량화 췌ㅅ로 말미암아 승용차의 차체는 박판일체식 구조로 제작되어 구조적 강성의 약화를 가져 왔으며 이로 인하여 외부의 요인으로부터 발생되는 승용차의 진동문제는 더욱 악화되고 해결하기 어렵게 되어가고 있다. 이 논문에서는 이러한 여러가지 문제로 인하여 전륜구동형 승용차의 조향계에서 발생되는 Shake와 Shimmy를 2-모드 동흡진기를 사용하여 제어하고자 하며 실제적으로 시작품을 제작하여 실차상태에서 확인시험을 실시하였다.