• Current Optics and Photonics
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• v.7 no.1
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• pp.65-72
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• 2023

The motion of organelles inside a cell is an important intrinsic indicator for assessing cell physiology and tissue viability. Dynamic contrast full-field optical coherence tomography (D-FFOCT) is a promising imaging technology that can visualize intracellular movements using the variance of temporal interference signals caused by biological motions. However, double-path interferometry in D-FFOCT can be highly vulnerable to surrounding noise, which may cause turbulence in the interference signals, contaminating the sample dynamics. Therefore, we propose a method for stabilized D-FFOCT imaging in noisy environments by using common-path interferometry in D-FFOCT. A comparative study shows that D-FFOCT with the proposed method achieves stable dynamic contrast imaging of a scattering phantom in motion that is over tenfold more noise-insensitive compared to the conventional one, and thus this imaging capability can provide cleaner motion contrast images. With the proposed approach, the intracellular dynamics of biological samples are imaged and monitored.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1824-1827
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• 1997

Majority of industrial robots are controlled by a simple joint servo control of joint actuators. In this type of control, the performance of control is influenced greatly by the joint interaction torques including Coriolis and centrifugal forces, which act as disturbance torques to the control system. As the speed of the robot increases, the effect of this disturbance torque increases, and makes the high speed-high precision control more difficult to achieve. In this paper, the joint disturbance torque of robots is analyzed. The joint disturbance torque is defined using the coefficients of dynamic equation of motion, and for the case of a 2DOF planar robot, the conditions for the maximum joint disturbance torques are identified, and the effect of link parameters and joint variables on the joint disturbance torque are examined. Then, a solutioin to the optimal path placement problem is proposed that minimizes the joint disturbance torque are examined. then, a solution to the optimal path placement problem is proposed that minimizes the joint disturbance torque during a straight line motion. the proposed method is illustrated using computer simulation. the proposed solution method cna be applied to the class of robots that are controlled by independent joint sevo control, which includes the vast majority of industrial robots. By minimizing the joint disturbacne torque during the motion, the simple joint servo controlled robot can move with improved path tracking accuracy at high speed.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.1
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• pp.53-60
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• 2010

We propose a motion planning method for autonomous mobile robots. In order to minimize traveling time, a smooth path and a time optimal velocity profile should be generated under kinematic and dynamic constraints. In this paper, we develop an effective and practical method to generate a good solution with lower computation time. The initial path is obtained from voronoi diagram by Dijkstra's algorithm. Then the path is improved by changing the graph and path simultaneously. We apply the dynamic programming algorithm into the stage of improvement. Simulation results are presented to verify the performance of the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1245-1248
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• 2004

This paper presents a new technique to analyze data on the coordinate x, y, z and apply these data to design the motion control to improve the efficiency of the engraving machine so that it can engrave accordingly in 3 dimensions. First, the tool path on the x-y plane is analyzed to be synchronized with the z-axis. The digital data is then sent to the motion control to guide the movement of the engrave point on the x-y plane. Tool path moves along the x-axis with zero degree and different values of the y-axis according to the coordinate of the digital data and the analysis along z-axis to determine the depth for engraving. The depth can be specified from the gray level with the 256 levels of resolution. The data obtained includes the distances on x-axis, y-axis, and z-axis, the acceleration of the engrave point's movement, and the speed of the engrave point's movement. These data is then transfered to the motion control to guide the movement of the engrave point along the z-axis associated with the x-y plane. The results indicate that engraving using this technique is fast and continuous. The specimen obtained looks perfect in 3D view.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.879-888
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• 2013

This paper addresses the vision based local path planning system for obstacle avoidance. To handle the obstacles which exist beyond the field of view (FOV), we propose a Panoramic Environment Map (PEM) using the MDGHM-SIFT algorithm. Moreover, we propose a Complexity Measure (CM) and Fuzzy logic-based Avoidance Motion Selection (FAMS) system to enable a humanoid robot to automatically decide its own direction and walking motion when avoiding an obstacle. The CM provides automation in deciding the direction of avoidance, whereas the FAMS system chooses the avoidance path and walking motion, based on environment conditions such as the size of the obstacle and the available space around it. The proposed system was applied to a humanoid robot that we designed. The results of the experiment show that the proposed method can be effectively applied to decide the avoidance direction and the walking motion of a humanoid robot.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1285-1295
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• 2008

A research on a simulator for a side walking path of a 16 degree-of-freedom (d.o.f) biped walking robot(BWR) which is composed of 4 d.o.f upper-part body and 12 d.o.f lower-part of the body is presented. For generation of stable side walking motion, the kinematics, dynamics and the zero moment of point(ZMP) of the BWR were analyzed analytically and included in the simulator. To operate the motion simulator for stable side walking of the BWR, a graphic user interface program was developed which needs inputs for the side distance between legs, base joint angle, walking type, and walking velocity. The simulator was developed to generate joint angle data of legs for side walking, and the data are transmitted to the BWR for stable side walking. In the simulator, a new path function for smooth walking motion was proposed and applied to the simulator and actual motion of a BWR. Also for actual side walking, an algorithm for estimating backlashes of the actuating joint motors was proposed and included in the simulator. To validate the performance of the proposed motion simulator, the simulator was operated and its side walking data of the simulator were generated for a period of side walking.

• The Journal of Korea Robotics Society
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• v.2 no.3
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• pp.275-281
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• 2007

This paper presents a motion planning strategy for legged robots using locomotion primitives in the complex 3D environments. First, we define configuration, motion primitives and locomotion primitives for legged robots. A hierarchical motion planning method based on a combination of 2.5 dimensional maps of the 3D workspace is proposed. A global navigation map is obtained using 2.5 dimensional maps such as an obstacle height map, a passage map, and a gradient map of obstacles to distinguish obstacles. A high-level path planner finds a global path from a 2D navigation map. A mid-level planner creates sub-goals that help the legged robot efficiently cope with various obstacles using only a small set of locomotion primitives that are useful for stable navigation of the robot. A local obstacle map that describes the edge or border of the obstacles is used to find the sub-goals along the global path. A low-level planner searches for a feasible sequence of locomotion primitives between sub-goals. We use heuristic algorithm in local motion planner. The proposed planning method is verified by both locomotion and soccer experiments on a small biped robot in a cluttered environment. Experiment results show an improvement in motion stability.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.545-550
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• 1991

Recently, the use of robots for painting operations has received much attention, as it is a powerful means for automation and quality improvement. Collision-avoidance is a key issue in the path planning for painting operations. In this paper, we develop a computationally efficient algorithm for the generation of collision-free path for two types of motion: a) Gross motion when the robot approaches the painting area, and b) Fine motion while spraying the surface. The former is a typical collision-avoidance problem, but the latter calls for special attention as the painting mechanics has to be incorporated into path planning. The developed algorithm is applied for the internal coating of the car body whose structure is the major source of collision.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.161-166
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• 2011

This paper addresses the vision based autonomous walking control system. To handle the obstacles which exist beyond the field of view(FOV), we used the 3d panoramic depth image. Moreover, to decide the avoidance direction and walking motion of a humanoid robot for the obstacle avoidance by itself, we proposed the vision based path planning using 3d panoramic depth image. In the vision based path planning, the path and walking motion are decided under environment condition such as the size of obstacle and available avoidance space. The vision based path planning is applied to a humanoid robot, URIA. The results from these evaluations show that the proposed method can be effectively applied to decide the avoidance direction and the walking motion of a practical humanoid robot.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.3
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• pp.192-198
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• 2016

Motion planning problem is still one of the important issues in robotic applications. In many real-time motion planning problems, it is advisable to find a feasible solution quickly and improve the found solution toward the optimal one before the previously-arranged motion plan ends. For such reasons, sampling-based approaches are becoming popular for real-time application. Especially the use of a rapidly exploring random $tree^*$ ($RRT^*$) algorithm is attractive in real-time application, because it is possible to approach an optimal solution by iterating itself. This paper presents a modified version of informed $RRT^*$ which is an extended version of $RRT^*$ to increase the rate of convergence to optimal solution by improving the sampling method of $RRT^*$. In online motion planning, the robot plans a path while simultaneously moving along the planned path. Therefore, the part of the path near the robot is less likely to be sampled extensively. For a better solution in online motion planning, we modified the sampling method of informed $RRT^*$ by combining with the sampling method to improve the path nearby robot. With comparison among basic $RRT^*$, informed $RRT^*$ and the proposed $RRT^*$ in online motion planning, the proposed $RRT^*$ showed the best result by representing the closest solution to optimum.