Beom H. Lee

Complete coverage path planning for cleaning task using multiple robots

This paper proposes a novel path planning method for cleaning task using multiple robots in large environment. To do so, we suggested algorithm which partitions a given region into several smaller regions and plans the covering path which can completely cover these divided areas. The algorithm also allocates the planed areas to cleaning robots sequentially and generates the paths which robots can take, when moving from an area to another area, in the shortest time. For partitioning the given region into several small areas, the Virtual Door Algorithm is used, and for planning the paths, the template-based approach is used. Previously generated look-up table, which uses the Dijkstra algorithm, is used for determining the path from one are to another. The Task Area Allocation Algorithm, which allocates the divided areas to cleaning robots using look-up table, is used for planning paths that cover the area completely. Finally, we evaluated the performance of our algorithms which can completely cover the given region regardless of the number of cleaning robots and verify the effectiveness of our proposed algorithms through computer simulations.

Multi-robot cooperative formation for overweight object transportation

This paper presents cooperative formation to transport an overweight object by means of multi-robot. Previous studies on object transportation have mainly focused on multi-robot coordination and architecture. However, successful object transportation is strongly related to the robot formation in the real world. Based on this need, we suggest what is termed the pusher-puller formation, which relies on pushing and pulling (or grasping) behaviors. The pusher pushes an object from behind, and the puller pulls it from the front. This formation was more robust and stable than others: straight-line and symmetrical formation. Real experiments are presented to test the validity and practicality of the proposed approach.

Computer modeling of the rhamnogalacturonase-"hairy" pectin complex.

The structure of a pectin‐bound complex of rhamnogalacturonase was modeled to identify the amino acid residues involved in catalysis and substrate binding. The “hairy” region of pectin, represented by six repeating stretches of (1→4)‐D‐galacturonate‐(1→2)‐L‐rhamnose dimer, was flexibly docked into the putative binding site of rhamnogalacturonase from Aspergillus aculeatus whose X‐ray structure is known. A search of the complex configurational space was performed using AutoDock for the dimeric and tetrameric sugar units in which the −1 galacturonate residue has various ring conformations. Then the plausible AutoDock solutions were manually extended to the dodecameric pectin models. Subsequently, the resulting complex models were subjected to solvated molecular dynamics using AMBER. In the best model, the substrate has an extended pseudo‐threefold helix with the −1 ring in a 4H3 half‐chair that approaches the transition state conformation. The catalytic machinery is clearly defined: Asp197 is a general acid and the activated water bound between Asp177 and Glu198 is a nucleophile. The active site is similar, with a small yet significant difference, to that of polygalacturonase that degrades the pectic “smooth” region of linear homopolymer of D‐(1→4)‐linked galacturonic acid. Rhamnogalacturonase has ten binding subsites ranging from −3 to +7, while polygalacturonase has eight subsites from −5 to +3. The model suggests that the eight amino acids including three arginine and three lysine residues, all of which are invariantly conserved in the rhamnogalacturonase family of proteins, are important in substrate binding. The present study may aid in designing mutational studies to characterize rhamnogalacturonase. Proteins 2004.

Moving obstacle avoidance for a mobile robot

This paper presents the near time-optimal motion planning method for moving obstacle avoidance. We decomposed the robot motion into three phases: approach, contact, and detachment phase. The constraints of each phase for a feasible collision-free robot motion were described by three necessary and sufficient conditions and one sufficient condition. We formulated the near time-optimal motion planning as optimization problem with inequality constraints. Simulations present the efficiency of the results by comparing them with two widely used approaches: reactive and path-velocity decomposed approach.

Multi-robot enclosing formation for moving target capture

In a problem of target capturing for multiple robots, it is an issue that the target is fixed or movable. When the target is fixed, the problem is solved by enclosing the target. However, it is useless if the target moves. We have investigated the restrictive velocity of the target that the robots can maintain the enclosing formation. The velocity of the target is supposed to be constant and smaller than the maximum velocity of the robots. Simulations demonstrate the restrictive condition for the target by showing the enclosing formation is not maintained when the restrictive condition is not satisfied.

Cooperative Object Transportation Using Connected Robots

This paper presents cooperative object transportation using connected robots. Previous studies of object transportation mainly used pushing or grasping methods to manipulate objects. A pushing method, however, cannot control the object motion precisely and a grasping method requires complicated gripping action before the transportation. Therefore, we suggest a new object transportation method which uses a rope. The method consists of three phases according to the behavior: the approaching, enclosing and transportation phases. Robots and an object have different formation controllers in accordance with their phases. Real experiments are presented to prove the validity of the proposed method.

Makespan Prediction Algorithm for Dedicated Robots Task Allocation

One method of dedicated robots task allocation has selected a task to be assigned after comparing the results when tasks are allocated to robots, respectively. Thus, quick and accurate prediction of makespan is important for enhancing the be solved in polynomial time. In this paper, the makespan prediction is mathematically analyzed and a greed algorithm is suggested on the basis of the analysis. The effectiveness of the makespan prediction algorithm was verified by simulation in comparison with the complete enumeration.

Distant object recognition with Grabcut for an active-zooming camera

In this paper a method for distant object recognition is proposed. We propose an iterative structure for distant object recognition using an active-zooming camera like PTZ camera. We adopt Graphcut-based segmentation algorithm, Grabcut, to our structure in order to select candidate regions for zooming and gazing. Grabcut is utilized through the modified strategy for our purpose. And we also propose two failure detection methods based on contour points and homography for our object recognition system. We show that our candidate region selection method is available for distance change from the camera, and also validate our recognition method through the real experiment.

High precision control of magnetically driven microtools for cell manipulations

This paper presents two innovative driving methodologies using magnetically driven microtools for precise cell manipulations and its automation systems. First, the magnetic analysis has been conducted to show the current MMT problem. Then, the new driving methodologies are introduced and backed up with FEM analysis and the experimental results. The positioning accuracy improves 3–10 times and the following response become 10 times higher against the driving linear stage. Using this methodology, the enucleation of oocytes is demonstrated to show the effectiveness of the method.