Extrinsic Calibration of a Camera and Laser Range Finder Using a New Calibration Structure of a Plane with a Triangular Hole

하종은 제어·로봇·시스템학회 2012 International Journal of Control, Automation, and Vol.10 No.6

Sensor fusion of a camera and laser range finder is important for the autonomous navigation of mobile robots. Finding the transformation between the camera and laser range finder is the first nec-essary step for the fusion of information. Many algorithms have been proposed, but these tend to re-quire many different steps in order to achieve reliable and accurate results. A calibration structure that has triangular hole on its plane is proposed for the extrinsic calibration of a camera and laser range finder. Locations of laser scan data that are invisible on the calibration plane can be determined using property on the proposed calibration structure. First, we classify the laser scan data into two groups where one is on the plane and the other is off the plane. Then, we determine the absolute location of the laser scan data on the plane through a search of the parameters of the line. Finally, we can establish 3D-3D correspondences between the camera and laser range finder. Extrinsic calibration between a camera and laser range finder is found using a conventional 3D-3D transformation computing algorithm.

레이저 거리 측정기 기반 투명 장애물 인식 방법

박정수(Jung-Soo Park),정진우(Jin-Woo Jung) 한국지능시스템학회 2014 한국지능시스템학회논문지 Vol.24 No.2

투명 장애물이 포함된 환경에서 레이저 거리 측정기만을 사용하여 장애물을 인식하다는 것은 이동 로봇이 장애물과의 충돌로부터 자유로운 자율 주행을 보장할 수 없는 문제를 야기한다. 이를 해결하기 위해 레이저 거리 측정기를 사용하는 이동 로봇은 투명 장애물을 인식할 수 있는 초음파 센서와 같은 추가적인 센서를 사용해야 한다. 본 논문에서는 레이저 거리측정기만을 이용하여 환경 내에 존재하는 투명 장애물을 인식할 수 있도록 하는 투명 장애물 인식 알고리즘을 제안한다. 투명 장애물 인식 알고리즘은 레이저 거리 측정기를 이용하여 투명 장애물을 인식하였을 경우, 투명 장애물에 의해 발생되는 반사 잡음(reflected noise)만을 추출하여 이를 처리함으로서 투명 장애물의 위치를 찾도록 하는 것이다. 이를 통해 이동 로봇은 투명 장애물 환경에서 레이저 거리 측정기만을 사용하더라도 장애물과의 충돌로부터 자유로운 자율 주행을 보장받을 수 있다. 또한 본 논문에서 제안한 알고리즘의 유효성을 평가하기 위해 세 가지의 실험 환경에서 실제 이동 로봇 및 레이저 거리 측정기를 사용하여 측정하였다. Using only laser range finder to detect the obstacles in an environment that contains transparent obstacles can not guarantee autonomous mobile robot from collision problem. To solve this problem, a mobile robot using laser range finder must be used additional sensor device such as sonar sensor that can detect the transparent obstacle. In this paper, a method is addressed to deal with the problem to detect the transparent obstacles within environment only by using laser range finder for mobile robot. In case the recognized transparent obstacle, the proposed algorithm is to localize the transparent obstacle to extract and process the reflected noise. This algorithm ensures autonomous of mobile robot only using laser range finder. The effectiveness of the proposed algorithm is evaluated by the real mobile robot and real laser range finder experiments with three case studies.

Improved Algorithm for the Extrinsic Calibration of a Camera and Laser Range Finder using 3D-3D Correspondences

하종은 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.5

Extrinsic calibration between a camera and laser range finder (LRF) is required to integrate information from both sensor. In this paper, we propose an improved algorithm of our earlier work [1] for the extrinsic calibration of a camera and laser range finder. We improve our previous algorithm in two directions. First, control points on laser range finder’s data are obtained by finding the crossing point of two fitted lines where previous algorithm directly used laser range finder’s data. It can reduce the effect of noisy measurement of laser range finder. Second, difference of distance on calibration plane is used as cost where previous algorithm used matching portion. Proposed algorithm gives an improved result than previous one. It is verified thorough experimental results.

Laser-range-finder based Field Ridge Detecting for Transplanter

( Jiajun Zhu ),( Michihisa Iida ),( Hoang-son Le ),( Masahiko Suguri ),( Ryohei Masuda ),( Kouji Miyake ),( Satoru Konishi ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.1

When a rice transplanter runs automatically in a rice paddy field, field ridge detection is an important part, it can provide the stop position for transplanter. In this paper, a method to detect the field ridge by a single Laser-Range-Finder equipped on the transplanter is presented. The base machine is an 8-row rice transplanter, this transplanter can be operated up to a maximum speed of 1.85 m/s. The LRF can determine the distance from transplanter to ridge in the real time, and depending on this distance, the transplanter decreases speed and stops automatically. The field test is conducted to evaluate the performance of the LRF based field ridge detection in the field. As the result, the detection accuracy is high enough for actual application.

Development of safety system for electric wheelchair with thermography camera

Tomoyuki Ohkubo,Kazuyuki Kobayashi,Kajiro Watanabe,Yosuke Kurihara 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8

This paper describes the development of a safety system for electric wheelchairs applying a thermography camera, laser range finder, and head mounted display. The combination of thermography camera and laser range finder can detect obstacles and/or humans even in the dark. The main problem the thermography camera is the narrow viewing angle. To overcome this problem, we developed a real-time obstacle tracking system that consists of a thermography camera and laser range finder. The combination of devices achieves robust tracking without the time-consuming complicated image processing required in conventional obstacle tracking. To confirm the validity of the proposed approach, we tested the newly developed system in an actual environment.

레이저 빔 궤적을 이용한 강인한 랜딩 시스템

황진아(Jin-Ah Hwang),남기군(Gi-Gun Nam),이장명(Jang-Myung Lee) 대한전기학회 2006 정보 및 제어 심포지엄 논문집 Vol.2006 No.1

This paper proposes a method of container position measurement using automatic landing system that is estimated by a laser range finder. In the most of container position measurement methods, CCD cameras or laser scanners have been used to get the source data. However those sensors are not only weak for disturbances, for examples, the light, fog, and rain, but also the system cost is high. When the spreader arrives the goal position, it is still swung by inertia or by wind effect. In this paper, the spreader swung data have been used to find the container position. The laser range finder is equipped in the front side of spreader. It can measure distance and relative position between spreader and container. This laser range finder can be rotated as desired by a motor. And a tilt sensor is equipped on the spreader to measure spreader sway. We estimate the relative position information between the spreader and a container using the laser range finder and tilt sensor through the geometrical analysis.

레이저 거리측정기 반복율 개선을 통한 거리측정 성능 향상

윤재복 ( Jae-bok Yoon ) 조선대학교 공학기술연구원 2017 공학기술논문지 Vol.10 No.3

Improving the viability of a tank by adding new systems is most effective in terms of technological aspects. However, this method is limited, because of the amount of time and money added during hardware / software changes. So it is also required to upgrade the existing technologies to accommodate the minimum amount of investment and change. This paper examines the vulnerability of existing Laser Range Finder. Performance improvements are achieved through minimal modification. Further, the improvement of performance was verified by checking the result of improvement through actual product.

FMCW 레이저 거리 측정기의 비선형성 보정 방법

정수용(Soo-Yong Jung),이성로(Seong Ro Lee),정민아(Min A Jeong),박창수(Chang-Soo Park) 한국통신학회 2013 韓國通信學會論文誌 Vol.38 No.4(융합기술)

본 논문에서는 연속파 주파수 변조(FMCW) 레이저 거리 측정기에서 주파수 변화의 비선형성을 보정하는 기술을 제안하였다. FMCW 기반의 레이저 거리측정기는 높은 거리 분해능을 위해 주파수 변화의 선형성이 요구되며, 비선형성이 존재할 경우 비트 신호의 주파수가 일정하지 않아 거리 측정 성능에 심각한 영향을 미치게 된다. 하지만 일반적으로 주파수 변조를 위해 사용하는 VCO(Voltage Controlled Oscillator)의 출력은 비선형적인 특성을 가지게 된다. 이와 같은 주파수 변화의 비선형성을 보정하기 위하여 본 논문에서는 보조 딜레이 구조를 사용하였다. 보조 딜레이 구조에서 생성되는 신호는 거리 정보를 가진 비트 신호와 동일한 변화율을 가지며, ADC(Analog to Digital Converter)의 Trigger 신호로 사용된다. 즉, 비트 신호의 주파수와 동일한 변화율을 가지는 신호를 Trigger로 사용하여 비트 신호를 샘플링 함으로 비선형성이 보정되어 일정한 비트 주파수를 얻을 수 있고, 따라서 정확한 거리 측정을 할 수 있게 된다. 이에 대한 성능을 검증하기 위해 실험을 수행하여 그 결과를 제시하였다. 제안한 방식에 의해 비성형성으로 인한 FMCW 레이저 거리 측정기의 측정 오차를 개선하여 시스템의 성능이 향상되는 것을 확인할 수 있었다. We propose a correction method of nonlinear frequency sweep in an FMCW(Frequency Modulated Continuous Wave) laser range finder. FMCW laser range finder requires linear frequency sweep for high resolution, and nonlinear frequency sweep makes the system performance degrade. In general, VCO(Voltage Controlled Oscillator) which is a component used for frequency modulation in FMCW method has nonlinear property. To correct the nonlinear frequency sweep, we utilize an auxiliary delay structure for generating trigger signal of ADC(Analog to Digital Converter). Because the trigger signal has same rate of change with the beat signal, the nonlinearity of the beat signal can be corrected. the experimental results show that the proposed method effectively eliminates the nonlinear frequency sweep problem and enhances the system performance.

레이저 거리측정기반 지형예측 시스템 개발

김태원(Tae-won Kim),고윤호(Yun-ho Ko) 제어로봇시스템학회 2010 제어로봇시스템학회 각 지부별 자료집 Vol.2010 No.12

Measurement of topography is important to autonomous vehicle and mobile robot. autonomous vehicle and mobile robot must have topography information for unmanned driving. topography information is essential in getting optimum course. this paper deal with development of the Land-preview system and simulator using laser range finder. also propose algorithm for getting change to mobile robot’s heave.

레이저 비전을 이용한 3차원 측정 시스템 구현

權孝根(Hyo Geun Kwon),千瑛碩(Young Seok Chun),徐榮秀(Young Soo Suh),盧塋植(Young Shick Ro) 대한전기학회 2007 전기학회논문지 Vol.56 No.5

A laser vision system is developed to measure the three-dimensional feature of an object. This system consists of two low cost cameras and a cross laser. One camera and a cross laser are used to measure a plane equation of an object. Using this information, the other camera measures a hole size of an object. The proposed system provides 0.05 ㎜ accuracy measurement systems with relatively low cost.