• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2018년도 하계학술대회
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• pp.43-44
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• 2018

본 논문에서는 로봇 매니퓰레이터의 순방향 기구학 학습에 있어서 로봇의 비용적인 측면으로 인하여 실재 로봇 매니퓰레이터를 교보재로 사용하여 실습을 하기에 제한되는 환경과 교재만으로 학습하는 제한된 환경에서 학생들이 이해하는 것 뿐만 아니라 검증이나 실험을 하기가 어려운 점을 개선하기 위해서 증강현실 기반의 시뮬레이터를 제안한다 로봇 기구학에서는 주로 교재를 사용하는데 실재로 존재하는 모델보다 회전 관절(revolute joint)과 병진 관절(prismatic joint) 모형의 조합으로 모델링한다 관절의 모형을 일종의 증강현실의 마커로 사용하여 교재에서 제안하는 모델에 더해서 개인이 조합한 모델 또한 실습이 가능하도록 하는 증강현실 시뮬레이터를 제안한다.

• 로봇학회논문지
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• 제17권1호
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• pp.58-67
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• 2022

In this paper, we propose an approach resolving inaccuracy of the low-cost redundant manipulator workspace with low encoder and low stiffness. When the manipulators are manufactured with low-cost encoders and low-cost links, the robots can run into workspace inaccuracy issues. Furthermore, trajectory generation based on conventional forward/inverse kinematics without taking into account inaccuracy issues will introduce the risk of end-effector fluctuations. Hence, we propose an optimization for the trajectory generation method based on the DDPG (Deep Deterministic Policy Gradient) algorithm for the low-cost redundant manipulators reaching the target position in Euclidean space. We designed the DDPG algorithm minimizing the distance along with the jacobian condition number. The training environment is selected with an error rate of randomly generated joint spaces in a simulator that implemented real-world physics, the test environment is a real robotic experiment and demonstrated our approach.

• 한국정밀공학회지
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• 제14권1호
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• pp.78-83
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• 1997

The paper presents the experimental analysis of a Stewart platform-based force-torque senor. The closed-form solution of forward kinematics of the Stewart platform is derived approximately by way of a linearization technique, and the solution is used in the force analysis of the force-torque sensor. An exper- mental studies show that the proposed method including gravity compensation algorithm is valid for Stew- art platform-based force-torque sensors. The performance of the developed force-torque sensor is evaluated in view of accuracy and linearity in measurements.

• 한국운동역학회지
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• 제17권2호
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• pp.227-237
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• 2007

The purpose of this study was to examine the effect of precision that kinematics had when short approach shots were taken. In this study, the subjects chosen were 5 skilled and 5 unskilled subjects, who were allowed to shoot 10 rounds of shots at target distances of 1m, 2m, 4m, and 8m. Three dimensional analysis was used as methods to obtain kinematics of each shots. In order to verify the statistical significance of the kinematic factors followed by the results of different skills and target distances, we used the two-way repeated ANOVA. The study was experimented within the level of p<.05. The results obtained were as follows: 1) the difference of shots of the forward and backward variations were larger than those of the left and right variations, the unskilled subjects' shot distances greatly got larger than that of the skilled subjects as the distance of the target increased, 2) not being affected by the target distance variations, the skilled subjects' rate of down-swing was shorter than the back-swing on short approach shots, 3) the skilled subjects' center of body weight tended to move more naturally towards the target when doing the down-swing to finish than that of the unskilled subjects on short approach shots, 4) the skilled subjects' right hand angle of cocking were narrower and tended to be kept much more consistent than that of the unskilled subjects on short approach shots, 5) the unskilled subjects when doing their back-swings, their right hips swayed towards the back, their trunk-flexion angles were shown to be lower than that of the skilled subjects on short approach shots, 6) the skilled subjects`body weight tended to move more naturally towards the left foot when doing the down-swing to finish than that of the unskilled subjects on short approach shots.

• 한국체육학회지인문사회과학편
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• 제53권2호
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• pp.531-540
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• 2014

본 연구는 두 종류의 공기주입식 카약 보트의 성능 비교와 함께 선수들의 카약 전방 스트로크 동작의 차이점을 비교 분석하여 보다 효율적이고 안전한 카약 보트를 찾는 데 목적이 있다. 이를 위해 대한 체육회 소속 K 고등학교 엘리트 남자 선수 5명이 연구에 참여하였으며, K고 실내 수영장에서 실험을 실시하였다. 보트의 성능 평가를 위해 보트 속도, 보트 좌우 흔들림 각도 차이, 보트의 회전 평균 각속도를 산출하였으며 선수의 수행력 차이를 분석하기 위해 몸통의 회전 가동범위, 무릎 관절의 굴곡-신전 가동범위, 몸통의 최대 회전 각속도, 무릎관절의 최대 신전 각속도, 상하지 근육의 활성도를 산출하였다. 연구 결과 선수들의 수행력 평가 변인에서는 통계적으로 유의한 수치를 보이지 않았다. 보트의 성능 평가 변인에서는 보트의 속도에서 B보트가 통계적으로 유의하게 빨랐으며 다른 변인들은 통계적으로 유의한 차이를 보이지 않았다. 결국 길이가 상대적으로 길고 폭이 상대적으로 좁은 B보트는 A보트와 비교했을 때 비슷한 안전성을 갖고 있으면서 보다 효율성을 나타내었다.

• 한국운동역학회지
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• 제19권3호
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• pp.467-479
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• 2009

제주마를 이용한 경속보(rising trot)시 숙련정도에 따라 2보폭동안 기승자세를 비교 분석하여 교육과정에 응용 할 수 있는 정량적 자료를 제시한다. 참여한 피험자는 총 10명(숙련군: 5명, 미숙련군: 5명)이었고, 실험 및 분석 방법은 3차원 영상분석(Kwon3D Motion Analysis System)을 하였고, 분석변인은 국면 및 이벤트별 시간, 선 및 각운동변인이었다. 숙련군이 미숙련군에 비해 상대적으로 지지기보다 공중국면의 소요시간 비율이 더 많았고, 국면경과에 따라 더 적은 상하운동범위 속에서, 전후 및 좌우속도에서 더 일관된 속도를 유지하였고, 상하방향에서 말의 보조와 동조를 이루면서 일관된 주기를 이루면서 반동운동이 이루어졌다. 숙련군이 미숙련군에 비해 상대적으로 팔꿈치에서 더 많은 굴곡 및 국면경과에 따라 어깨의 더 많은 후방신전자세를 취하였다. 고관절과 무릎은 더 많은 전방굴곡자세를 취한 반면 발목의 경우 모두 저측굴곡의 자세를 유지하였다. 동체는 수직축에 대해 후방신전자세인 반면 미숙련군은 전방굴곡자세를 유지하였다. 즉 미숙련군의 경우 숙련군에 비해 다소 경속보에서 보조의 경과에 따라 불안한 자세를 취한 것으로 사료된다.

• Journal of Mechanical Science and Technology
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• 제16권8호
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• pp.1053-1063
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• 2002

This paper presents a robust nonlinear controller for a f degree of freedom (DOF) parallel manipulator in the task space coordinates. The proposed control strategy requires information on orientations and translations in the task space unlike the joint space or link space control scheme. Although a 6 DOF sensor may provide such information in a straightforward manner, its cost calls for a more economical alternative. A novel indirect method based on the readily available length information engages as a potential candidate to replace a 6 DOF sensor. The indirect approach generates the necessary information by solving the forward kinematics and subsequently applying alpha-beta-gamma tracker With the 6 DOF signals available, a robust nonlinear task space control (RNTC) scheme is proposed based on the Lyapunov redesign method, whose stability is rigorously proved. The performance of the proposed RNTC with the new estimation scheme is evaluated via experiments. First, the results of the estimator are compared with the rate-gyro signals, which indicates excellent agreement. Then, the RNTC with on-line estimated 6 DOF data is shown to achieve excellent control performance to sinusoidal inputs, which is superior to those of a commonly used proportional-plus-integral-plus-derivative controller with a feedforward friction compensation under joint space coordinates and the nonlinear controller under task space coordinates.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1481-1484
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• 1997

The vehicle driving simulator expects vehicle motion with real-time simulation arise from driver's steering, accelerating, stopping and simulates motion of vehicl with visula, audio and washout algorithm. And it gives a vivid feeling to driver in reality. Vehicle driving simulator with vehicle integration control system is used for analysis of analysis of vehicle controllaility, steering capacity and safety in various pseudo environment alike. basides, it analyzeds vehicle safety factor dirver's reaction and promotes traffic safety without driver's own risks. The main proceduress of development of the vehicle driving simulator are classified by 3 parts. first the motion base system which can be generated by the motion queues, should be developed. Secondly, real-time vehicle software which can afford the vehicle dynamics, might be constructed. The third procedure is the integration of vehicle driing simulator which can be interconnected between visual systems with motion base. In this study, we are to study of the motion base for a vehicle driving simulator design and that of its real time control and using an extra gyro sensor and accelerometers to find a position and an orientatiion of the moving platform except for calculating forward kinematics. To drive the motion base, we use National Instruments corp's Labview software. Furthemore, we use analysis module for the vehicle motionand the washout algorithm module to consummate driving simulator, which can be driven by human in reality, so we are doing experimentally process about various vehicle motion conditon.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2737-2742
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• 2003

Kinematic calibration enhances absolute accuracy by compensating for the fabrication tolerances and installation errors. Effectiveness of calibration procedures depends greatly on the measurements performed. While the Cartesian postures are measured completely, all of the geometric parameters can be identified to their true values. With partial pose measurements, however, few geometric parameters may not be identifiable and effectiveness of the calibration results may vary significantly within the workspace. QR decomposition of the identification Jacobian matrix can reveal the non-identifiable parameters. Selecting postures for measurement is also an important issue for efficient calibration procedure. Typically, the condition number of the identification Jacobian is minimized to find optimum postures. This paper investigates identifiable parameters and optimum postures for four different calibration procedures - measuring postures completely with inverse kinematic residuals, measuring postures completely with forward kinematics residuals, measuring only the three position components, and restraining the mobility of the end-effector using a constraint link. The study is performed for a six degree-of-freedom fully parallel HexaSlide type paralle manipulator, HSM. Results verify that all parameters are identifiable with complete posture measurements. For the case of position measurements, one and for the case of constraint link, three parameters were found non-identifiable. Optimal postures showed the same trend of orienting themselves on the boundaries of the search space.

• Journal of Mechanical Science and Technology
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• 제16권6호
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• pp.799-809
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• 2002

In order to utilize a parallel mechanism as a machine tool component, it is important to estimate the errors of its end-effector due to the uncertainties in parts. This study proposes an error analysis for a new parallel device, a cubic parallel mechanism. For the parallel device, we consider two kinds of errors. One is a static error due to link stiffness and the other is a dynamic error due to clearances in the parts. In this study, we propose a stiffness model for the cubic parallel mechanism under the assumption that the link stiffness is a linear function of the link length. Also, from the fact that the errors of u-joints and spherical joints are changed with the direction of force acting on the link, they are regarded as a part of link errors, and then the error model is derived using forward kinematics. Lastly, both the error models are integrated into the total error, which is analyzed with a test example that the platform moves along a circular path. This analysis can be used in predicting the accuracy of other parallel devices.