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Sangyul Park,Hasun Lee,Dongjun Lee 제어로봇시스템학회 2020 제어로봇시스템학회 국제학술대회 논문집 Vol.2020 No.10
We propose CPG (central pattern generator) based robot control framework constructed based on: 1) the inverse model of the CPG that directly encodes resultant body motion of the robot in CPG parameters; and 2) the CPG parameter adaptation law that enforces robustness of the controller. These two components behaves as feedforward and feedback control for the CPG controlled robot, enabling us to achieve fast and robust generation of a desired body motion for robotic systems operated within complex environmental interaction. The inverse CPG model is constructed based on neural network along with autoencoder to efficiently deal with the dimension decrease from input to output of the model. Also, the CPG parameter adaptation is done with a concept of backpropagation, which is enabled by the adoption of smooth activation function for the inverse CPG model. For the development and verification of the proposed framework, simulation is conducted with two robotic systems, snake-like robot and pivotboard system.
ODAR: Aerial Manipulation Platform Enabling Omnidirectional Wrench Generation
Park, Sangyul,Lee, Jeongseob,Ahn, Joonmo,Kim, Myungsin,Her, Jongbeom,Yang, Gi-Hun,Lee, Dongjun IEEE 2018 IEEE/ASME transactions on mechatronics Vol.23 No.4
<P>We propose a novel aerial manipulation platform, an omnidirectional aerial robot, that is capable of omnidirectional wrench generation with opportunistically distributed/aligned Sectional rotors. To circumvent the tight thrust margin and weight budget of currently available rotor and battery technologies, we propose a novel design optimization framework, which maximizes the minimum-guaranteed control force/torque for any attitude while incorporating such important and useful aspects as interrotor aerointerference, anisotropic task requirement, gravity compensation, etc. We also provide a closed-form solution of infinity-norm optimal control allocation to avoid rotor saturation with the tight thrust margin. Further, we elaborate the notion of electronic speed controller induced singularity and devise a novel selective mapping algorithm to substantially subdue its destabilizing effect. Experiments are performed to validate the theory, which demonstrate such capabilities not possible with typical aerial manipulation systems, namely, separate translation and attitude control on SE(3), hybrid pose/wrench control with downward force of 60 N much larger than its own weight (2.6 kg), and peg-in-hole teleoperation with a radial tolerance of 0.5 mm.</P>
이상열(Sangyul Lee),장서윤(Seoyun Jang),박원아(Wonah Park),박철웅(Cheolwoong Park) 대한기계학회 2019 大韓機械學會論文集B Vol.43 No.7
연료 분사 모듈은 대표적인 중소기업 아이템 중의 하나이나, 대부분의 업체들이 체계적인 설계기술 및 설계 tool을 확보하고 있지 못한 실정이다. 연료 분사 모듈 설계에 사용되는 기존 상용 설계 및 해석 프로그램은 고비용과 전문성의 한계로 인해 중소기업에서 활용하기 힘든 측면이 있다. 이런 이유로, 국내 노즐 업체들이 쉽게 사용할 수 있는 연료 분사용 노즐 설계/해석 tool 개발의 필요성이 제기되고 있다. 본 연구는 연료분사모듈 설계 프로그램용 코드 구조를 개발하고 플랫폼 연동용 input/output 코드를 개발하는 것을 연구 목표로 하였다. 오픈소스 3D 연소해석 프로그램인 KIVA의 서브루틴을 분석한 후 분사 모듈 개발에 필요한 코드를 개발하고, 기존 코드 및 실험결과와 비교, 검증하였다. Fuel injection module is one of the representative small and medium enterprise items, but most companies do not have systematic design technology and design tool. The existing commercial design and analysis programs used in fuel injection module design are difficult to utilize in SMEs due to their high cost and limited expertise. For this reason, there is a need to develop fuel injection nozzle design / analysis tool which domestic nozzle manufacturers can easily use. The purpose of this study is to develop code structure for fuel injection module design program and to develop input / output code for platform linkage. After analyzing the subroutines of KIVA which is an open source 3D combustion simulation program, we developed the code necessary to develop the injection module and compared it with the results of the old code and experiments.
부분 예혼합 압축착화 연소를 위한 다단 분사 및 피스톤 보울 형상에 관한 연구
이상열(Sangyul Lee),박원아(Wonah Park),민경덕(Kyoungdoug Min) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4
To reduce diesel engine emission, partially homogeneous charge combustion ignition diesel engine with split injection was simulated. Some conditions compared to the conventional injection strategy were evaluated and soot was reduced but NOx was not. Due to the early injection, pressure and temperature in the piston is low and spray was collided to the piston liner, combustion was poor and HC and CO would be increased. To eliminate the collision, retarded the injection timing and modified the bowl geometry and NOx and soot is reduced a bit quantity. At last, piston bowl was modified for spray reentrance. In this results, NOx and soot was enomously reduced..
A wet-tolerant adhesive patch inspired by protuberances in suction cups of octopi
Baik, Sangyul,Kim, Da Wan,Park, Youngjin,Lee, Tae-Jin,Ho Bhang, Suk,Pang, Changhyun Nature Publishing Group 2017 Nature Vol. No.
<P>Adhesion strategies that rely on mechanical interlocking or molecular attractions between surfaces can suffer when coming into contact with liquids(1,2). Thus far, artificial wet and dry adhesives have included hierarchical mushroom-shaped or porous structures that allow suction or capillarity(3-6), supramolecular structures comprising nanoparticles(7), and chemistry-based attractants that use various protein polyelectrolytes(8-10). However, it is challenging to develop adhesives that are simple to make and also perform well- and repeatedly-under both wet and dry conditions, while avoiding non-chemical contamination on the adhered surfaces(11). Here we present an artificial, biologically inspired, reversible wet/dry adhesion system that is based on the dome-like protuberances found in the suction cups of octopi. To mimic the architecture of these protuberances(12-14), we use a simple, solution-based, air-trap technique that involves fabricating a patterned structure as a polymeric master, and using it to produce a reversed architecture, without any sophisticated chemical syntheses or surface modifications. The micrometre-scale domes in our artificial adhesive enhance the suction stress. This octopus-inspired system exhibits strong, reversible, highly repeatable adhesion to silicon wafers, glass, and rough skin surfaces under various conditions (dry, moist, under water and under oil). To demonstrate a potential application, we also used our adhesive to transport a large silicon wafer in air and under water without any resulting surface contamination.</P>
하상렬(Sangyul Ha),박태욱(TaeUk Park),김기태(KiTae Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
In this paper, we developed a physically-based micromechanical model for inelastic deformation of ceramic powders. The aggregate response of ceramic particles was modeled using the two-surface yield function which considered the shear-induced dilatancy caused by friction, rolling resistance and cohesion between powder particles and consolidation caused by plastic deformation of powder themselves under high compression. The constitutive equations were implemented into the user-subroutine VUMAT of finite element program ABAQUS/Explicit. The material parameters in the constitutive model were identified by calibrating the model to reproduce data from triaxial compression tests and simple compression tests. The density distribution obtained by using the proposed model was in good quantitative agreement with the experimental results of the triaxial compression and cold isostaic compression as well.
유한요소해석을 활용한 전자 패키지 휨에서 물성 산포의 영향 분석
박수빈(Soobean Park),김두형(Doohyeong Kim),하상렬(Sangyul Ha),이용석(Yong-Seok Lee) 대한기계학회 2023 대한기계학회 춘추학술대회 Vol.2023 No.11
Warpage behavior prediction is one of important skill in electronic packages. Currently, the prediction of warpage behavior is based on average values. In this study, we analyzed how the warpage changes when the mechanical property distribution is considered in the warpage behavior through finite element analysis. Based on the results, we will introduce the influence of mechanical property scatter and the important properties factors to control the warpage.