• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.1458-1462
• /
• 2003

High temperature and high pressure heavy water flows through the pipes in atomic power plants. The curved parts of pipes are critical parts in that they change the direction of steam flow, and these parts are especially affected by severe wear. Therefore, most pipes in atomic power plants are tested by non-destructive examination by workers who use ultrasonic sensors to measure the wall thickness of pipes. But not only are these pipes located in a very dangerous environment, but the space is also very limited. For the safety of workers, it is necessary to design a device that uses a mobile robot that can inspect curved pipes. This paper presents the design and construction of a small device that can generate the necessary contact forces between ultrasonic sensors and pipe walls in a limited space. And a mobile robot is used in place ortho worker for successful non-destructive examination.

• 제어로봇시스템학회:학술대회논문집
• /
• 1990.10b
• /
• pp.985-989
• /
• 1990

This paper presents a fundamental study of a millimeter-sized master-slave robot driven by conduit-guided wires, which is expected to be applied to the delicate surgical operations, the assembling precise and small parts and so on. This system consists of a millimeter-sized slave robot and a master manipulator of which the size is adapted to a human finger. Displacement and torque of the master side can be reduced and transferred to the slave robot by controlling the motor torque against the master torque by feeding back tension signals. The master can feel the tensions by the motor torque. In this paper, the design method and making process of the master-slave system and the dynamical characteristic of displacement and torque control are proposed.

• Journal of Advanced Marine Engineering and Technology
• /
• v.22 no.2
• /
• pp.232-240
• /
• 1998

This paper deals with a hybrid position/force control of a robot which is moving on the constrained object with constant force. The proposed controller is composed of a position and force controller. The position controller has a nonlinear compensator which is based on the dynamic robot model and the force controller is attached by feedforward element. A direct drive robot with hard nonlinearity which is controlled by the proposed algorithm has moved on the constrained object with a high stiffness and low stiffness. The results show that the proposed controller has more vibration suppression effects which is occurred to the constrained object with a high stiffness, than a existing feedback controller, and accurate force control can be obtained by comparatively a small feedback gain.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.10 no.3
• /
• pp.203-209
• /
• 2010

This paper presents a hierarchical fuzzy motion planner for humanoid robots in 3D uneven environments. First, we define both motion primitives and locomotion primitives of humanoid robots. A high-level planner finds a global path from a global navigation map that is generated based on a combination of 2.5 dimensional maps of the workspace. We use a passage map, an obstacle map and a gradient map of obstacles to distinguish obstacles. A mid-level planner creates subgoals that help the robot efficiently cope with various obstacles using only a small set of locomotion primitives that are useful for stable navigation of the robot. We use a local obstacle map to find the subgoals along the global path. A low-level planner searches for an optimal sequence of locomotion primitives between subgoals by using fuzzy motion planning. We verify our approach on a virtual humanoid robot in a simulated environment. Simulation results show a reduction in planning time and the feasibility of the proposed method.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.507-510
• /
• 2002

We developed a human-sized BWR(biped walking robot) named KUBIRI driven by a new actuator based on the ball screw which has high strength and high gear ratio. KUBIRI was developed to walk autonomously such that it is actuated by small torque motors and is boarded with DC battery and controllers. To utilize informations on the human walking motion and to analyze the walking mode of robot, a motion capture system was developed. The system is composed of the mechanical and electronic devices to obtain the joint angle data. By using the obtained data, a 3-D graphic interfacer was developed based on the open inventor tool. Through the graphic interfacer, the control input of KUBIRI is performed.

• The Journal of Korea Robotics Society
• /
• v.3 no.2
• /
• pp.106-111
• /
• 2008

This paper presents a decentralized coordination for a small-scale mobile robot teams performing a task through cooperation. Robot teams are required to generate and maintain various geometric patterns adapting to an environment and/or a task in many cooperative applications. In particular, all robots must continue to strive toward achieving the team's mission even if some members fail to perform their role. Toward this end, given the number of robots in a team, an effective coordination is investigated for decentralized formation control strategies. Specifically, all members are required first to reach agreement on their coordinate system and have an identifier (ID) for role assignment in a self-organizing way. Then, employing IDs on individual robots within a common coordinate system, a decentralized neighbor-referenced formation control is realized to generate, keep, and switch between different geometric shapes. This approach is verified using an in-house simulator and physical mobile robots. We detail and evaluate the formation control approach, whose common features include self-organization, robustness, and flexibility.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.39 no.9
• /
• pp.985-996
• /
• 1990

An inverse kinematic solution of a robot manipulator using multilayer perceptrons is proposed. Neural networks allow the solution of some complex nonlinear equations such as the inverse kinematics of a robot manipulator without the need for its model. However, the back-propagation (BP) learning rule for multilayer perceptrons has the major limitation of being too slow in learning to be practical. In this paper, a new algorithm named Dynamically Reconfiguring BP is proposed to improve its learning speed. It uses a modified version of Kohonen's Self-Organizing Feature Map (SOFM) to partition the input space and for each input point, select a subset of the hidden processing elements or neurons. A subset of the original network results from these selected neuron which learns the desired mapping for this small input region. It is this selective property that accelerates convergence as well as enhances resolution. This network was used to learn the parity function and further, to solve the inverse kinematic problem of a robot manipulator. The results demonstrate faster learning than the BP network.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.50 no.6
• /
• pp.283-294
• /
• 2001

In this paper, a masterarm for teleoperation of humanoid robot is presented. This masterarm is based human kinematics, which not only mimics human posture/motion completely, but also has wider work range. In addition, by using the distributed controller architecture and electric brake for force reflection, small size and lightweight of the device can be achieved. Some size and lightweight of the device can be achieved. Some important experiments integrated with the humanoid robot, CENTAUR developed by KIST(Korea Institute of Science and Technology), are conducted to evaluate the performance of the proposed masterarm.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.804-809
• /
• 2004

This paper introduces a link-type tracked vehicle which is developed for demining operations. The vehicle consists of three parts - front frame, rear frame and body. The front frame is connected to the rear frame by a rotational passive adaptation mechanism which is a driving mechanism of the vehicle. Additionally, the demining system which is adaptable to mobile robot is developed to clear small Anti-Personnel(AP) mines with inexplosive method. In other words, assembled rakes unearth mines by their opposite rotation to the direction of the robot. Finally, the motions of demining rakes and design parameters of the demining system are analyzed.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.16 no.6
• /
• pp.217-222
• /
• 2007

This paper describes a static gait generation process and a mechanical design process of leg mechanisms for quadruped robots. Actually robot walking is realized with the joint motion of leg mechanisms. In order to calculate the time-angle trajectories for each joint of leg mechanisms, we generate end-tip trajectories with time for each leg in the global inertial coordinate system intuitively, followed by coordinate transformations of the trajectories into the local coordinates system fixed in each leg, finally the angle-time trajectories of each joint of leg mechanisms are obtained with inverse kinematics. The stability of the gait generated in this paper was verified by a multi-body dynamic analysis using the commercial software $ADAMS^{(R)}$. Additionally the mechanical specifications such as gear reduction ratio, electrical specifications of motor and electrical power consumption during walking have been confirmed by the multi-body dynamic analysis. Finally we constructed a small quadruped robot and confirmed the gait.