Zakarya Zyada

GPR Signal Processing with Geography Adaptive Scanning using Vector Radar for Antipersonal Landmine Detection

Ground Penetrating Radar (GPR) is a promising sensor for landmine detection, however there are two major problems to overcome. One is the rough ground surface. The other problem is the distance between the antennas of GPR. It remains irremovable clutters on a sub-surface image output from GPR by first problem. Geography adaptive scanning is useful to image objects beneath rough ground surface. Second problem makes larger the nonlinearity of the relationship between the time for propagation and the depth of a buried object, imaging the small objects such as an antipersonnel landmine closer to the antennas. In this paper, we modify Kirchhoff migration so as to account for not only the variation of position of the sensor head, but also the antennas alignment of the vector radar. The validity of this method is discussed through application to the signals acquired in experiments.

Identification and modeling of friction forces at a hydraulic parallel link manipulator joints

Compensation for friction is essential for accurate assembly. Friction identification and modeling is the first step towards compensation for its effect. We propose an identification method and modeling of friction forces at the prismatic joints of a six d.o.f. hydraulically powered parallel link manipulator. First, we introduce a mathematical basis for friction forces identification at every prismatic joint, and then we identify friction forces at the prismatic joints using pressure sensors experimentally. The proposed method does not use any additional instruments or sensors, neither does it need any special design of the manipulator joints and hence, it is cost effective and reliable. We also present an experimental evaluation of friction forces at every prismatic joint based on the proposed method. A suitable model for friction forces at the joints is determined. The results show that friction forces may differ from one actuator to another as every actuator has its own characteristics. This assures the need for proper compensation for every actuator friction forces.

Motion Control of Landmine Detection Vehicle Equipped with Low-Ground-Pressure Tires

Most of landmine detection robots proposed before have been strongly restricted to locomote because they have not been able to enter the minefield. So we have proposed a mine detection vehicle which can enter minefield with low-ground-pressure tires and scan landmines directly using GPR. Low-ground-pressure tire decrease ground contact pressure. And we are intended to make accurate map that point out the position where landmines are buried. The position of the vehicle is able to be observed with internal sensors (for the posture measurement) and external sensors (for the position measurement). However, when controlling the vehicle, the sampling time of external sensors and communication time from external sensors to the vehicle cannot be disregarded. Exact position of the vehicle must be predicted with dynamical model of the vehicle. We therefore propose dynamical model of the vehicle for low-ground-pressure vehicle. Based on experimental results, the dynamical model for low-ground-pressure vehicle is in consistency with actual behavior of it

Fuzzy modeling of a hydraulic parallel link manipulator actuators' forces

We present a fuzzy-logic based model for every hydraulic actuator of a parallel link manipulator. Construction of a fuzzy model rule base is composed of two stages; the first stage is: learning rules from examples for the acquired input/output data; while the second stage is: completing the unknown fuzzy rules from heuristics and experience. The algorithm of fuzzy-rule base modeling as well as the actuators forces results from models and experiments, for a 6 DOF Stewart platform, are presented.

GPR Environmental-Based Landmine Automatic Detection

According to the United Nations, as of the year 2000 there were 70 million landmines planted in a third of the world’s nations affecting global causality rate of up to 20,000/year, (Anderson, 2002). That is why landmine detection has attracted much attention by many research teams around the world during the last two decades; among them is our research team in Nagoya University. Anti-personnel (AP) mine ranges from 5 to 15 cm in size; they can be metal, plastic, or wood. AP mines are normally buried at shallow depth; detonated by very low pressure, and designated to kill or maim people. PMN2, Type72 and PMN are examples, Fig. 1. In real world clearance activities, AP mine suspect areas are divided into 1 m grid squares, and each square meter is probed with a bayonet or plastic rod. Probing is done at an oblique angle to the ground so that the rod will encounter the side of a land mine and not trip the fuse. No need to say, this work is very dangerous and proceeds very slow, (Siegel, 2002). The need for a safer and more fast humanitarian demining action by replacing a manual sensing task by vehicle sensing task have motivated our research team to introduce a low-ground-pressure tires detection vehicle, (Hasegawa et al, 2004-A). The unmanned vehicle that can move in mine field without detonating a group of AP mines will be presented in this chapter. One of the big challenges in demining process is detection. If a mine is detected, deminers can explode, mark or move it to a pit for later detonation or defusing. Conventional mine detection, by a metal detector, is often difficult for two reasons. First, mines are increasingly being made of plastics, minimizing the more easily detectable metal components. Second, mined areas are often equipped with metal scraps creating a high false alarm rate. Because of the difficulty encountered in detecting the tiny amounts of metal in a plastic landmine with a metal detector, technology development has been extended to other sensors. Ground penetrating radar (GPR) used for about 70 years for a variety of geophysical subsurface imaging applications including utility mapping and hazardous waste container has been actively applied to the problem of land mine detection for nearly the last two decades of research. It provides sensing objects underground based on dielectric properties. It senses the reflected electromagnetic wave by a buried object. It is expected that GPR be a good alternative sensor and/or an important support sensor when fused with a metal detector for