A new method for measuring the effective complex relative permittivity of a reflecting surface is presented. The approach is based on the two-ray model. We derive an equation of a circle representing the complex reflection coefficient which relates the incidence angle, frequency, and received power from the path gain using the two-ray model. The intersection point of three such circles at different heights, while maintaining the same incidence angle, yields the correct complex reflection coefficient value. By measuring the received power for both the vertical and horizontal polarizations, the relative permittivity of the surface can be determined. The technique is validated using computer simulation, as well as field measurements of typical terrain surfaces, such as asphalt, grass, and bare soil. A major advantage of this method is that it obviates the need to use antennas with a narrow beam pattern.

OmniKity-II (OK-II) is a mobile base which is developed as an omnidirectional mobile robot. In this paper the structure of OK-II including actuators, vision and infrared sensors is described. As an application shooting behavior in robot soccer is demonstrated. Fuzzy logic controller from the authors' previous result is used for the shooting action control. The omnidirectional mobility makes the motion control much easier as shown in the experimental results.

The structure of OmniKity-I (OK-I), the miniature omni-directional mobile robot, and its kinematics and dynamics models are presented. OK-I has three DOFs in the plane. A conventional two wheeled mobile robot (2-WMR) serves as the base of OK-I for translational motion. The robot body is on top of the base. The third motor controls angular motion of the body as the base turns according to the translational motion. The circular surface connector (CSC) is devised to transfer signals from the base to the body without constraining angular motion of the body. Experimental results show proper omni-directional features of OK-I.

The soccer robot system consists of multi agents, with highly coordinated operation and movements so as to fulfill specific objectives, even under adverse situation. The coordination of the multi-agents is associated with a lot of supplementary work in advance. The associated issues are the position correction, prevention of communication congestion, local information sensing in addition to the need for imitating the human-like decision making. A control structure for a soccer robot is designed and several behaviors and actions for a soccer robot are proposed. Modified zone defense as a basic strategy and several special strategies for fouls are applied to SOTY and MIRO teams for MIROSOT (Micro-Robot World Cup Soccer Tournament).