Yoon-Gu Kim

Portable fire evacuation guide robot system

Robot technology is emerging for applications in disaster prevention with devices such as fire-fighting robots, rescue robots, and surveillance robots. In this paper, we suggest an portable fire evacuation guide robot system that can be thrown into a fire site to gather environmental information, search displaced people, and evacuate them from the fire site. This spool-like small and light mobile robot can be easily carried and remotely controlled by means of a laptop-sized tele-operator. It contains the following functional units: a camera to capture the fire site; sensors to gather temperature data, CO gas, and O2 concentrations; and a microphone with speaker for emergency voice communications between firefighter and victims. The robots design gives its high-temperature protection, excellent waterproofing, and high impact resistance. Laboratory tests were performed for evaluating the performance of the proposed evacuation guide robot system.

Localization of Mobile Robot Based on Fusion of Artificial Landmark and RF TDOA Distance under Indoor Sensor Network

In this paper, we propose a robust and real-time localization method for dynamic environments based on a sensor network; the method combines landmark image information obtained from an ordinary camera and distance information obtained from sensor nodes in an indoor environment. The sensor network provides an effective method for a mobile robot to adapt to changes and guides it across a geographical network area. To enhance the performance, we used a charge-coupled device (CCD) camera and artificial landmarks for self-localization. Experimental results showed that global localization can be achieved with high robustness and accuracy using the proposed localization method.

A Fuzzy Obstacle Avoidance Controller Using a Lookup-Table Sharing Method and Its Applications for Mobile Robots

A Lookup-Table (LUT) based design enhances the processing speed of a fuzzy obstacle avoidance controller by reducing the operation time. Also, a LUT sharing method provides efficient ways of reducing the LUT memory size. In order to share the LUT which is used for a fuzzy obstacle avoidance controller, an idea of using a basis function is developed. As applications of the shared LUT-based fuzzy controller, a laser-sensor-based fuzzy controller and an ultrasonic-sensor-based fuzzy controller are introduced in this paper. This paper suggests a LUT sharing method that reduces the LUT buffer size without a significant degradation of the performance. The LUT sharing method makes the buffer size independent of the fuzzy systems complexity. A simulation using MSRDS (Microsoft Robotics Developer Studio) is used to evaluate the proposed method. To investigate the performance of the controller, experiments are carried out using a Pioneer P3-DX with LabVIEW as an integration tool. Although the simulation and experiments show little difference between the fully valued LUT-based method and the LUT sharing method in terms of the operation time, the LUT sharing method reduces almost 95% of the full-valued LUT-based buffer size.

Adaptive driving mode control of mobile platform with wheel-track hybrid type for rough terrain in the civil environment

Various robot platforms have been designed and developed to perform given tasks in a hazardous environment for the purpose of surveillance, reconnaissance, search and rescue, and etc. We have considered a terrain adaptive hybrid robot platform which is equipped with rapid navigation on flat floors and good performance on overcoming stairs or obstacles. Since our special consideration is posed to its flexibility for real application, we devised a design of a transformable robot structure which consists of an ordinary wheeled structure to navigate fast on flat floor and a variable tracked structure to climb stairs effectively. Especially, track arms installed in front side, rear side, and mid side are used for navigation mode transition between flatland navigation and stairs climbing. The mode transition is determined and implemented by adaptive driving mode control of mobile robot. The wheel and track hybrid mobile platform apparatus applied off-road driving mechanism for various professional service robots is verified through experiments for navigation performance in real and test-bed environment.

Enhanced localization for team robot navigation using compass sensor and USN

This paper presents an enhanced localization for team robot navigation in an unknown environment. Localization information from encoder is subject to noise resulting from friction between road surface and wheels, or the error in motor itself, in the environment. In addition, the measured error is accumulative as a robot navigates. The mobility in disaster situations is more serious because of the unstable environment. In order to solve these problems, we proposed a localization and navigation system which is comprised of an 802.15.4a protocol based communication module to measure the distance between team robots and a compass sensor to get the heading angle of every robot. The proposed method is based on a modified Kalman Filter which is adapted in our system to improve the quality of 802.15.4a protocol and compass sensor for reducing the error in measurement process. From the experimental results, we will verify better performance of the proposed system for more practical localization and navigation in the disaster sites through the team robot cooperation.

Decentralized cooperative mean approach to collision avoidance for nonholonomic mobile robots

This paper presents a novel, decentralized, control-theoretic approach to address collision avoidance for multi-robot systems. We create a virtual obstacle at the mean position of the robots. A control is be designed such that each robot will avoid the closest obstacle when a collision is possible. The closest obstacle can be the virtual obstacle or the nearest robot. We present two such control laws. The first assumes perfect knowledge of the velocities of all nearby robots and can allow a saturated velocity input for each robot. In practice, the velocities of the other robots are hard to measure or estimate precisely. Therefore, the second control law removes the assumption of known velocities based on a high-gain, robust control scheme. We prove the first control scheme is globally asymptotically stable, and the robust control law is globally uniformly ultimately bounded. To verify the effectiveness of the proposed approach, Monte Carlo simulations and experiments have been conducted.

Symmetric caging formation for convex polygonal object transportation by multiple mobile robots based on fuzzy sliding mode control

In this paper, the problem of object caging and transporting is considered for multiple mobile robots. With the consideration of minimizing the number of robots and decreasing the rotation of the object, the proper points are calculated and assigned to the multiple mobile robots to allow them to form a symmetric caging formation. The caging formation guarantees that all of the Euclidean distances between any two adjacent robots are smaller than the minimal width of the polygonal object so that the object cannot escape. In order to avoid collision among robots, the parameter of the robots radius is utilized to design the caging formation, and the A⁎ algorithm is used so that mobile robots can move to the proper points. In order to avoid obstacles, the robots and the object are regarded as a rigid body to apply artificial potential field method. The fuzzy sliding mode control method is applied for tracking control of the nonholonomic mobile robots. Finally, the simulation and experimental results show that multiple mobile robots are able to cage and transport the polygonal object to the goal position, avoiding obstacles.

A switching formation strategy for obstacle avoidance of a multi-robot system based on robot priority model.

This paper describes a switching formation strategy for multi-robots with velocity constraints to avoid and cross obstacles. In the strategy, a leader robot plans a safe path using the geometric obstacle avoidance control method (GOACM). By calculating new desired distances and bearing angles with the leader robot, the follower robots switch into a safe formation. With considering collision avoidance, a novel robot priority model, based on the desired distance and bearing angle between the leader and follower robots, is designed during the obstacle avoidance process. The adaptive tracking control algorithm guarantees that the trajectory and velocity tracking errors converge to zero. To demonstrate the validity of the proposed methods, simulation and experiment results present that multi-robots effectively form and switch formation avoiding obstacles without collisions.

Symmetric caging formation for convex polygon object transportation by multiple mobile robots

In this paper, the problem of object caging and transporting is considered by multiple mobile robots using object closure technology. With the consideration of minimizing the number of the robots and decreasing the rotation of the object, the proper points are calculated and assigned to the multiple mobile robots to form the symmetric caging formation. The caging formation guarantees that all of the Euclidean distances between two adjacent robots are smaller than the minimal width of the polygon object and the object cannot escape. Finally, the simulation results represent multiple mobile robots which cage and transport the polygon object to the goal position.

Design and implementation of an optimal in-pipe navigation mechanism for a steel pipe cleaning robot

This study focuses on the design and implementation of an optimal pipe navigation mechanism and a driving unit to overcome the variable situations inside steel pipes. It also offers adaptability to different pipe diameters. The important problems considered in the design and implementation are a self-sustaining property when in the center of a pipe, optimal navigation ability to adapt to in-pipe unevenness, the capability to remain stable without slipping in pipes, and the efficient operation of cleaning equipment. The robot developed here based, on carefully determined design specifications, was tested to verify the performance of its navigation mechanism and driving ability. In addition, a control system was developed for the test. The ultimate goal is the application of the verified in-pipe cleaning robot to industrial and practical applications.