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Pixel-wise distortion model and its calibration method for AMCW LiDAR
Junwoo Jason Son,Youngbin Son,Byeongho Song,Soohee Han 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10
In this conference paper, we proposed pixel-wise distortion model and its calibration method for AMCW (Amplitude Modulated Continuous Wave) LiDAR (Light Detection and Ranging). The proposed model can be reflect square wave distortion, common mode error and non-linear characteristic of the receiving circuit. The model characterise the distance error with actual distance and amplitude of the DCS (Differential Correlation Sample). A simple calibration method is also announced in order to use the proposed model. The method uses modulation signal delay and shutter speed variation to measure the response of the receiving circuit. The experiment was carried out with various signal delay and shutter speed under simple calibration box. The result shows the response of the AMCW LiDAR was changed by both inputs and also the AMCW LiDAR can measure the distance without these errors by using the proposed model and calibration method.
IMU-integrated Optical Navigation System for Tracking Multi-agent
Seongwon Yoon,Junwoo Jason Son,Soohee Han 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10
In this paper, an IMU-integrated optical navigation system is presented. In the existing motion capture system, it was necessary to use the geometry of the recognized multiple markers to obtain the attitude of the object. On the other hand, in the proposed system, with only a small number of cameras, real-time output of 6-DOF including position and attitude was enabled by compactly implementing a single infrared marker with embedded IMU and computing board as an agent module. As a result of the development, it was possible to dramatically improve the problem of the existing rigid body-based attitude estimation method in which the attitude estimation error changes according to the distance from the cameras. In addition, according to the wireless time synchronization implementation of the camera and the agent, unique identification and tracking for each of the multiple agents operating in the same system was enabled. Therefore, this system is expected to have a very high potential for use in factory automation (FA) and robotics. In this paper, the principle of this system and each system component are explained.
Energy Consumption Analysis of Downward-Tethered Quadcopter
ChangHyeon Lee,Junwoo Jason Son,Hakjun Lee,Soohee Han 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10
This paper analyze the energy consumption of a new concept of tethered quadrotor system, downward tethered quadrotor (DTQ), to provide insight about using DTQ. DTQ is one of a tethered quadrotor system in which station is located above the flight level of the quadrotor. Thanks to its system layout, the tether can play an important role in energy efficient flight of the quadrotor by adjusting the tension properly. In order to extremize the advantage of DTQ, optimization problem for mechanical power consumption of DTQ in hovering states is formulated. The DTQ in this paper considers misalignment between tether link point on the quadrotor and center of mass (CoM) of the quadrotor to simulate real system. Numerical simulation illustrates efficiency of the proposed method.
Localization for mobile robots with a multi-ToF camera system
Chaewon Park,Junwoo Jason Son,Soohee Han 제어로봇시스템학회 2022 제어로봇시스템학회 국제학술대회 논문집 Vol.2022 No.11
The localization of mobile robots is the core function for the various solutions utilizing autonomous mobile robots. By comparison with 3D LiDAR which is expensive and bulky, the time-of-flight (ToF) camera is inexpensive and can be miniaturized. So it can greatly contribute to the diffusion of autonomous mobile robots. However, due to the limitations, such as mixed pixel effect and multipath interference, the measurement of ToF camera is noisy and inaccurate. Therefore, in order to obtain high-quality pose estimation with the low-cost ToF camera, a preprocessing process and localization algorithm considering the characteristics of the ToF camera are essential. We experimented with the possibility of localization using a multi-ToF camera system. In consideration of the FoV of the ToF camera, the scan data was acquired using a mobile robot with a multi-ToF camera system. The scan data was analyzed by comparing it with the high-resolution map acquired with the high-precision 3D LiDAR, and a preprocessing process for localization was implemented, taking account of the analyzed characteristics. By building the localization algorithm utilizing the iterative closest point (ICP) algorithm, the possibility of localization using the multi-ToF camera system was demonstrated.
Nonimaging Optical Irradiance Optimization for Enhanced ROI of Mobile Robot LiDAR
Ingyo Jeong,Youngbin Son,Junwoo Jason Son,Byeongho Song,Soohee Han 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10
In this paper, the design method of illumination optics for solid-state AMCW (Amplitude Modulated Continuous Wave) LiDAR (Light Detection And Ranging) is suggested. To satisfy the horizontally long and vertically narrow atypical ROI (Region of Interest) of LiDAR, the concept of etendue is applied. For light sources placed in a rectangle shape, the short side of the source corresponds to the slow axis and the long side corresponds to the fast axis. In order to cover a light source placed in a rectangle, a translational design in which the cross section of the lens is extended in the axial direction is adopted. The refractive surface of the lens is modeled with two parametric curves, and parameters are adjusted to satisfy the given radiance criteria. In the design example, the design of a primary lens composed of one circular arc and a secondary lens formed by connecting circular arcs was derived. The designed optical system showed an efficiency of about 65% and a uniformity of 12%.