Hocheol Shin

Development of a snake robot moving in a small diameter pipe

This paper presents a snake robot moving in a small diameter pipe. A snake robot is a multi-linked modular robot. The snake robot, KAEROT-snake IV consists of 11 2-DOF actuator modules, a head, and a tail module. Each of the 2-DOF actuator modules has two small DC motors and worm gear boxes to increase the torque output and an embedded motor controller. The snake robot can move in a small diameter pipe with a sequence of holding motion as well as with a sinusoidal motion. Some modules holds the robot itself by pressing outward to induce friction while the other modules move forward/backward and hold the robot at a more front/rear position. A sequence of holding moves the robot forward/backward in a small diameter pipe.

Trotting gait analysis of a lizard using motion capture

Research into the gait planning of a walking robot is the underlying development of quadruped robots. Despite the efforts in stable gait planning, many walking robots that have been developed thus far do not have enough ability to adapt to uneven territory. In this paper, we acquired the motion data of the trotting lizards using the motion capture equipment and analyzed the gait systematically. In addition, we applied it to the kinematic model of the lizard and acquired the trajectory of each joint through an inverse kinematic solution. Moreover, we proposed the joint space-based gait of the lizard model by approximating the acquired joint trajectory to a sinusoidal function. We verified through the simulation that the proposed gait faithfully follows actual gait of lizards.

A Mobile Robotic System for the Inspection and Repair of SG Tubes in NPPs

The reliability and performance of a steam generator (SG) is one of the serious concerns in the operation of pressurized water nuclear power plants. Because of high levels of radiation, robotic systems have been used to inspect and repair SG tubes. In this paper, we present a mobile robotic system that positions the inspection and repair tools while hanging down from the tube sheets where the tubes are fixed. All of the driving mechanisms of the mobile robot are actuated by electric motors to start its works, providing that the electric power is prepared without the additional need for an on-site air services. A special tube-holding mechanism with a high holding force has been developed to prevent falling from the tube sheets, even in the case of an electric power failure. We have also developed a quick installation guide device that guides the mobile robot to desired initial positions in the tube sheet exactly and quickly, which helps to reduce the radiation exposure of human workers during the installation work. This paper also provides on-site experimental results and lessons learned.

Aerial Working Environment Monitoring Robot in High Radiation Area

This paper describes the development of a robot monitoring an aerial working environment in a high radiation area such as the Calandria face at a PHWR (pressurized heavy water reactor) of a nuclear power plant. The robot consists of three main parts: a mobile platform, a telescopic mast, and a mission tool. To access the target place across the guide rail ditch of a shielding door, the mobile platform is equipped with two front rubber wheels, two rear omni-wheels, and four flippers. The telescopic mast installed on the platform is able to lift up the mission devices to the height of 10 m. The mission devices are a radio hardened camera, a leak detecting sensor, a dosimeter detecting high radiation level, and a RAM operating device of a fuel exchange machine. In addition, a control system considering the emergency was developed.

Trot gait simulation of four legged robot based on a sprawled gait

Lizards with a thin and flexible body can easily pass through a narrow path. Their sprawled gait increases their stability and allows them to overcome obstacles and rough terrain. Therefore, lizard bio-mimetic robots are suitable for reconnaissance and detection. The dynamic modeling of a lizard was carried out by weighing each link of a lizard and constructing its 3D shape using micro-CT scanning. We formulated a periodic sprawled gait which is able to describe the gait of lizards. In addition, we generated an upright gait by altering the gait parameters of the sprawled gait. The sprawled and upright gaits of the dynamic lizard model were simulated with various gait parameters using commercial dynamic analyzing software. The stable gait parameters for the stable trotting were obtained through the simulation.

Development of Multi-Body Dynamics Simulator for Bio-Mimetic Motion in Lizard Robot Design

이 수행되고 있다. 하지만 대부분의 도마뱀 로봇은 제한된 자유도로 인해 실제 도마뱀과 같은 범용적인 움직임을 수행할 수 없다는 단점이 있다. 이러한 도마뱀 생체모방 로봇을 설계하기 위해서는 수학적 모델을 이용한 다양한 시뮬레이션이 필요하며, 이러한 시뮬레이션을 기반으로 최적 경로를 생성하기 위한 경로 계획 및 구동력의 요구도 등을 구할 수 있다. 따라서, 본 연구에서는 모션 캡쳐와 Micro-CT 데이터를 이용하여 도마뱀의 운동을 모사할 수 있는 도마뱀 다물체 기구-동역학 모델을 개발 Key Words: Bio-Mimetic(생체모사), Motion Capture(모션 캡쳐), Multi-Body Dynamics Simulator (다물체 동역학 시뮬레이터), Lizard Robot(도마뱀 로봇) 초록: 본 논문에서는 도마뱀 로봇 설계를 위한 생체운동 모사 다물체 동역학 시뮬레이터가 개발되었다. 시뮬레이터에 사용된 다물체-기구 동역학 모델은 상용 소프트웨어인 RecurDyn 에 쿠반에놀 도마뱀의 모션 캡쳐 데이터와 Micro-CT 데이터를 적용하여 생성되었다. 다양한 도마뱀의 보행 운동 특성 해석을 위해서 생체운동 시뮬레이터는 궤적 생성모듈, 역기구학 모듈, 역동역학 모듈로 구성된다. 궤적생성 모듈은 도마뱀의 속도에 따른 척추운동과 발 궤적을 생성한다. 또한, 도마뱀 로봇 설계를 위해서 역기구학을 통한 관절 각도 계산과 그를 통한 역동역학 해석으로 이동속도에 대한 요구 조인트 구동력을 생성한다. Abstract: In this study, a multibody simulator was developed to analyze the bio-mimetic motion of a lizard robot design. A RecurDyn multibody dynamics model of a lizard was created using a micro-computerized tomography scan and motion capture data. The bio-mimetic motion simulator consisted of a trajectory generator, an inverse kinematics module, and an inverse dynamics module, which were used for various walking motion analyses of the developed lizard model. The trajectory generation module produces spinal movements and gait trajectories based on the lizards speed. Using the joint angle history from an inverse kinematic analysis, an inverse dynamic analysis can be carried out, and the required joint torques can be obtained for the lizard robot design. In order to investigate the effectiveness of the developed simulator, the required joint torques of the model were calculated using the simulator.

Obtaining contact parameters for MBDS of a wheelless snake robot

This paper shows a way to obtain contact parameters for multi-body dynamics simulation (MBDS) of a wheelless snake robot, KAEROT-snake V. We developed a simulation model of the snake robot in a commercial MBDS software RecurDyn(V8). RecurDyn provides a convenient way to model contact geometries directly from CAD models, which are very close to the actual shape. Contact parameters such as spring, damping and friction coefficient are very important in MBDS so that we obtained the contact parameters through experiments of falling and sliding test. The contact parameters were obtained by analyzing the images of the test and the MBDS simulation of the test. Some locomotion simulation results for the snake robot were experimentally verified.