Chomchana Trevai

Multiple mobile robot surveillance in unknown environments

This research aims to deal with the fundamental problems that arise in surveillance missions in complex environments in which a distributed multiple robot system is operating. In this research, task means the surveillance mission of the multiple robot system. The system-level task can be retrieved using the Reaction–Diffusion Equation on a Graph-based surveillance strategy planner. The task is the combination of observation points that the robots have to visit in order to gain complete information about the target environment. This paper contains several examples of methods used for task decomposition and allocation in surveillance tasks undertaken by multiple mobile robots. In an indoor environment, a robot group is first sent out in an exploration phase by the proposed distributed sensing and complete coverage strategy. The surveillance mission requires the iterative search of events over and over in the target environment. In the iterative surveillance operation, the robots monitor their individual coverage areas and update their local maps to account for environmental changes such as changes in position of authorized equipment, vehicles, etc. In order to quickly respond to such changes, in this research, the shortest cyclic path is aimed as a result of the iterative surveillance path. The shortest iterative surveillance path results in complete coverage of the target area at as a high a frequency as possible and maximum area covered in unit time.

Cooperative exploration of mobile robots using reaction-diffusion equation on a graph

In this paper, we propose cooperative exploration method for mobile robots in a working area. The method will generate and share the minimal-cost path for each mobile robot. Each mobile robot goes through several observation points to accomplish the exploration. The observation points should be arranged at a fixed distance from at least on corresponding observation point. In addition, the number of observation points and the lengths of paths for each mobile robot are to be minimized. The proposed method should have the efficiency in computational cost concurrently with the adaptability to dynamic environmental changes.

Controlling a mobile robot that searches for and rearranges objects with unknown locations and shapes

This paper offers a proposal for an algorithm of controlling a mobile robot that searches for and rearranges objects with unknown locations and shape. In this paper, we divide the task into two parts: exploration task and rearrangement task. The algorithms for each part of the task are presented with respect to the effectiveness of the path length and computational cost. Additionally integration algorithm that effectively combines exploration and rearrangement is presented. Experiments with a real robot are conducted to demonstrate the effectiveness of the proposed algorithm.

Exploration-path generation of multiple mobile robots using reaction-diffusion equation on a graph

In this paper we present a method for cooperative exploration by multiple mobile robots in a restricted working area. By generating and sharing the minimal-length path for each mobile robot in which mobile robots go through several observation points to explore the working area. The observation points should be arranged at a fixed distance from at least one corresponding observation point. Therefore, mobile robots can obtain the complete information of the working area by only moving along all of the observation points. To reduce the redundancy of exploration task, the number of observation points and the length of observation paths for each mobile robot are to be minimized. To ensure the advantages from using multiple mobile robots, exploration path must be equally assigned to each mobile robot. Simulations had proved the efficiency of cooperating mobile robots using our proposed method. The feasible of our method is real world with actual mobile robots was demonstrated in cooperative exploration experiment.

Real-Time Cooperative Exploration by Reaction-Diffusion Equation on a Graph

In this paper we present a path planning method for the environment exploration using the reaction-diffusion equation on a graph. We autonomously arrange sub-goals for robots to go along and explore the environment. By using reaction-diffusion on a graph for sub-goals arrangement, we can deal with the emergence of unknown objects or obstacles in the dynamic environment. This method also can explore the environment in real-time and make sure that robots completely explore all the area in the environment. The results given in this paper demonstrate that our method successfully solves exploration problems both in simulations and in real robot experiments.

Acquisition of intermediate goals for an agent executing multiple tasks

In this paper, an algorithm that acquires the intermediate goals between the initial and goal states is proposed for an agent executing multiple tasks. We demonstrate the algorithm in the problem of rearranging multiple objects. The result shows that the moving distance to transfer the entire objects to their goal configuration is 1/15 of that without using intermediate goals. We experiment using a real robot to confirm that the intermediate goal can be adapted to a real environment. Our experimental results showed that an agent could adapt the intermediate goals, which were acquired in the simulation, to the experimental environment

Local Obstacle Avoidance with Reliable Goal Acquisition for Mobile Robots

In this paper, we propose a method of obstacle avoidance and goal acquisition for mobile robots in unknown environments. We have modified the navigation method, Vector Field Histogram(VFH) by Borenstien et al. Our method, Sensor Based Vector Field Histogram(SBVFH), designs for more sensor-reactive method. Our method concerns the situation that several mobile robots travelling in the environment. The mobile robot is goal-directed while trying to avoid static and moving obstacles. The results of simulation and experiment show that the algorithm is efficient with relatively cheap sensors.

Mobile robot control for composition of seamless and high-resolution images in library

We are developing an assistant robot system for administration of a library. In this system, an autonomous mobile robot obtains images with a camera, and composes seamless and high-resolution images of a bookshelf by using mosaicing and super-resolution techniques. In this paper, we propose a control method for the robot in front of a bookshelf as a part of this system. To obtain images that are suitable for mosaicing, a robot should take images from the same distance and orientation to a bookshelf. Our control method utilizes horizontal edges, which are detected easily in any bookshelf. The robot modifies its orientation with the edge in camera images. We implemented a super-resolution and mosaicing algorithm. Our implementation is simple. However, it can compose a high quality image in an experiment, since the robot obtains preferable images for the image processing.

Mobile robot system for composition of seamless and high resolution images

Seamless and high resolution images that copy a room is expected to be used for many applications (e.g. a guard system, amusement, remote control, and so forth). We are developing a mobile robot system for obtaining such images automatically. This system utilizes single kind of line marker, which is adhesive tape and is attached horizontally by a user beforehand. A mobile robot goes round a room and builds map. The map is used to collect images of above part of each marker. It means that the mobile robot does not need to know prior information of the room. Therefor, the underlying problems in this paper are localization and exploration by a mobile robot without prior information of the environment.