Jin Shin

Omnidirectional Distance Measurement based on Active Structured Light Image

Abstract: In this paper, we proposed an omnidirectional ranging system that is able to obtain 360 o all directional distances effectively based on structured light image. The omnidirectional ranging system consists of laser structured light source and a catadioptric omnidirectional camera with a curved mirror. The proposed integro-differential structured light image processing algorithm makes the ranging system robust against environmental illumination condition. The omnidirectional ranging system is useful for map-building and self-localization of a mobile robot. Keywords: omnidirectional image, ranging system, laser structured light그림1. 구조광 영상 기반 전방향 거리측정 시스템.Fig. 1. Omnidirectional ranging system based on structured light image. I. 서론이동로봇의 자율주행을 위한 위치추정과 지도작성을 위해서는 주변 물체까지의 거리를 측정할 수 있는 센서가 필요하다. 거리측정 방식으로는 초음파 센서, 스테레오 카메라, 레이저 스캐너 등 다양한 종류의 센서들이 널리 사용되고 있다[1-3]. 구조광 영상기반 센서는 레이저와 같이 주변조명과 확연히 구별되는 구조광을 조사해주고, 물체거리에 따른 구조광 영상의 왜곡을 측정함으로써 거리를 측정하는 방식으로서 거리 계산이 효율적이고, 한 장의 영상으로 폭 넓은 거리정보를 얻을 수 있으며, 주변조명 잡음에 상대적으로 강인하다는 장점이 있다[1,4-6]. 특히 근래에는 반도체 레이저 발생장치와 저렴한 영상센서의 등장으로 매우 경제적인 구현이 가능해졌다.본 논문에서는 360도 전방향으로 수평 구조광을 조사하고, 전방향 거울(omnidirectional mirror)과 일반 카메라로 구성되는 전방향 영상 카메라를 통해 구조광 영상을 획득함으로써 360도 모든 방향의 거리를 기계적인 스캔을 통하지 않고 한 번에 측정할 수 있는 전 방향 거리센서에 대해 기술한다. 이동로봇은 이동공간상에서 전후좌우 어떤 방향으로든 운동할 수 있으므로 모든 방향의 거리정보는 이동로봇의 자율주행에 큰 도움이 될 수 있다. 본 논문에서 제안하는 구조광 영상기반 전 방향 거리센서는 한 번에 모든 방향의 거리를 동시 측정할 수 있으므로 매우 효율적이고,

Active Ranging Sensors Based on Structured Light Image for Mobile Robot

In this paper, we propose a ring array of active structured light image-based ranging sensors for a mobile robot. Since the ring array of ranging sensors can obtain omnidirectional distances to surrounding objects, it is useful for building a local distance map. By matching the local omnidirectional distance map with a given global object map, it is also possible to obtain the position and heading angle of a mobile robot in global coordinates. Experiments for omnidirectional distance measurement, matching, and localization were performed to verify the usefulness of the proposed ring array of active ranging sensors.

Development of Omnidirectional Ranging System Based on Structured Light Image

In this paper, a ranging system is proposed that is able to measure 360 degree omnidirectional distances to environment objects. The ranging system is based on the structured light imaging system with catadioptric omnidirectional mirror. In order to make the ranging system robust against environmental illumination, efficient structured light image processing algorithms are developed; sequential integration of difference images with modulated structured light and radial search based on Bresenham line drawing algorithm. A dedicated FPGA image processor is developed to speed up the overall image processing. Also the distance equation is derived in the omnidirectional imaging system with a hyperbolic mirror. It is expected that the omnidirectional ranging system is useful for mapping and localization of mobile robot. Experiments are carried out to verify the performance of the proposed ranging system.

Ring Array of Structured Light Image Based Ranging Sensor and Autonomous Navigation for Mobile Robot

In the paper, we proposed a ring type structured light image based embedded ranging sensor for a mobile robot. Since the proposed ranging sensor obtains omnidirectional object distance, it is useful for autonomous navigation of a mobile robot. By matching the local omnidirectional distance map with a given global object map, it is possible to get position and heading angle of mobile robot in the global coordinates. Experiments for matching and navigation were carried out to verify the performance of the proposed ranging sensor.

Development of Multi-functional Laser Pointer Mouse through Image Processing

A beam projector is popularly used for a presentation nowadays. In order to point out local area of the projected image, a laser pointer is used with it. Simple wireless presenter has only limited functions of a computer mouse(pointing device) such as “go to next slide” or “back to previous slide” in a specific application i.e., MS-PowerPoint, with wireless channel; thus, there is inconvenience to carry out other controls, e.g., execution or termination of an application and maximization or minimization of a window, etc. during the presentation. The main objective of this paper is to implement a wireless multi-functional laser pointer mouse that has the same functions of a computer mouse. In order to get position of the laser spot in the projector display, an image processing to detect the laser spot in the camera image is required. In addition, transformation of the spot position into computer display coordinates is needed to execute computer controls on the computer display.

Development of an Active Ranging System Based on Structured Light Image for Mobile Robot Application

This paper presents an active ranging system that is based on a laser structured-light image and is robust against environment illumination noise. Structured-light image processing is computationally more efficient than conventional stereo image processing since the burdensome correspondence problem is avoidable. In order to achieve robustness against illumination noise, we propose an efficient image processing algorithm, i.e., integration of sequential time-difference images with structured-light modulation. The proposed algorithm involves only elementary operations such as integer subtraction and addition and is appropriate for hardware implementation. For this algorithm, a specialized FPGA image processor is developed. A distance equation and sensitivity analysis are also presented.

An Omnidirectional Ranging System

In this paper, a ranging system is proposed that is able to measure distances to environment objects omnidirectionally, that is, over 360°. This ranging system is based on a structured-light imaging system with a catadioptric omnidirectional mirror. In order to make the ranging system robust against environmental illumination, efficient structured-light image processing algorithms have been developed: sequential integration of difference images with modulated structured light. A distance equation was derived for an omnidirectional imaging system with a hyperbolic mirror.

Image Search Method Based on Bresenham Raster Algorithm for Omnidirectional Structured Light Image

In this paper, we proposed a search method for structured light pixels of omnidirectional structured light image. Since the omnidirectional structured light image is composed of several circular arc segments, the proposed algorithm searches the structured light pixels in radial direction rather than horizontal or vertical directions. The proposed search algorithm is based on the well-known Bresenham raster algorithm for line drawing in discrete integer space, thereby computation of the algorithm is very efficient. Comparison results between the proposed search algorithm and the conventional horizontal search are presented in experiments.

An Image Processing for Omnidirectional Image Based on the Bresenham Raster Algorithm

In this paper, an image processing algorithm for omnidirectional image is proposed. Since the omnidirectional image contains many circular arc segments, a radial directional processing for certain features in the image is appropriate rather than the horizontal or vertical directional processing as in the usual rectangular shape image. Computation of the proposed radial processing algorithm is based on the well-known Bresenham raster algorithm for line drawing in discrete integer space, thereby it is very fast and efficient. Comparison between the proposed algorithm and the conventional horizontal processing in terms of feature detection and computational efficiency are presented in experiments.

Illumination Invariant Ranging Sensor Based on Structured Light Image

This paper presents an active ranging system based on laser structured-light image. The structured-light image processing is computationally efficient in comparison with the conventional stereo image processing, since the burdensome correspondence problem is avoidable. In order to achieve robustness against environmental illumination noise, an efficient image processing algorithm, i.e., integration of difference images with structured-light modulation is proposed. Distance equation from the measured structured light pixel distance and system parameter calibration are addressed in this paper. Experiments and analysis are carried out to verify performance of the proposed ranging system.