Dong Jin Seo

Trajectory modification using elastic force for collision avoidance of a mobile manipulator

This paper proposes a method for collision avoidance of a mobile manipulator. The method deals with the problem of driving a mobile manipulator from a starting configuration to a goal configuration avoiding obstacles. It modifies planned trajectory at every sampling time using elastic force and potential field force. It puts way poses throughout a planned trajectory, and the trajectory modification is accomplished by adjusting the way poses. The way poses are adjusted subject to the elastic force and the potential field force. The procedure repeats until the robot reaches its goal configuration through the way poses. This method results in smooth and adaptive trajectory in an environment with moving as well as stationary obstacles.

Simulator Implementing Uncertainties in Motion for Robots in a Network

This paper presents a simulator for multiple robot system. The simulator implements the uncertainties in the robot motion. The robots in the simulator are connected using the IPC (Inter Process Communication) which is based on TCP-IP. The simulator consists of the four units: communication, robot control, kinematic design, and driver for real robot operation. The robot control unit uses Gaussian noise to incorporate the uncertainties of robot motion. The real robots and virtual robots can operate in parallel. Also, by providing only the link parameters, a new robot can be added. Some application examples show that the simulator is useful and indispensable for verification of algorithms especially for complicated multiple robot systems. Moreover, it is shown that motion uncertainty of the robot plays an important role to evaluate the robustness performance of an algorithm.

Simulation of mobile robot motion considering uncertainties in robot model

This paper describes a simulator which emulates mobile robot motion. The simulator implements probabilistic model of robot motion and sensor output. The sensor implemented is a range sensor such as laser range finder which is used widely for obstacle detection, map making, and localization. The sensor model includes measurement noise with Gaussian distribution around true range value, failure of detection, and unexplainable random measurement. The motion model incorporates uncertainty with normal distribution. The simulator is used to test a collision avoidance algorithm. In practical application of the mobile robot, major problems arise due to the unexpected uncertainty of motion and sensor. The simulator is useful to predict the problems of robot motion before the robot is deployed in the field. For wider availability, the simulator can be further developed to include error model of various sensors.

Local collision avoidance of multiple robots using avoidability measure and relative distance

This paper presents a new method driving multiple robots to their goal position without collision. To consider the movement of the robots in a work area, we adopt the concept of avoidability measure. The avoidability measure figures the degree of how easily a robot can avoid other robots considering the velocity of the robots. To implement the concept to avoid collision among multiple robots, relative distance between the robots is proposed. The relative distance is a virtual distance between robots indicating the threat of collision between the robots. Based on the relative distance, the method calculates repulsive force against a robot from the other robots. Also, attractive force toward the goal position is calculated in terms of the relative distance. These repulsive force and attractive force are added to form the driving force for robot motion. The proposed method is simulated for several cases. The results show that the proposed method steers robots to open space anticipating the approach of other robots. In contrast, since the usual potential field method initiates avoidance motion later than the proposed method, it sometimes fails preventing collision or causes hasty motion to avoid other robots. The proposed method works as a local collision-free motion coordination method in conjunction with higher level of task planning and path planning method for multiple robots to do a collaborative job.

Development of Realtime EtherCAT Master Library Using INtime

This paper proposes an architecture of a real-time EtherCAT master library called RtEML. The controls EtherCAT slaves under EtherCAT protocol in real-time. It provides a simple programming interface which is useful in developing robot application in C/C++ or C#. To achieve deterministic, hard real-time control in Microsoft Windows environment without additional hardware, INtime is used. Since INtime is designed specifically to take advantage of the powerful capabilities of the x86 processor architecture, the proposed RtEML achieves microseconds of real-time performance.

Ubiquitous robotic companion systems implemented with standard tools for integration

This paper describes a paradigm which implements ubiquitous environment with service robots and equipments. The paradigm provides the method for integration of service robots and equipments in the environment as well as that for integrating components in service robot. Also it suggests the communication among the robots and equipments as well as communication among the components of a robot. It is used for implementation of distributed URC systems which is installed in several universities and Institute in Korea. The field application demonstrates the feasibility of the proposed method.