Determination of a vehicle or person's position and/or orientation is a critical task for a multitude of applications ranging from automated cars and first responders to missiles and fighter jets. Most of these applications rely primarily on global navigation satellite systems, e.g., GPS, which are highly vulnerable to degradation whether by environmental factors or malicious actions. The use of inertial navigation techniques has been shown to provide increased reliability of navigation systems in these situations. Due to advances in MEMS technology and processing capabilities, the use of small and low-cost inertial measurement units (IMUs) are becoming increasingly feasible, which results in small size, weight and power (SWaP) solutions. A known limitation of MEMS IMUs are errors that causes the navigation solution to drift; furthermore, calibration and initialization are challenging tasks. In this paper, we investigate the use of multiple IMUs to aid in calibrating the navigation system and obtaining accurate initialization by performing fine alignment. By using a centralized filter, physical constraints between the multiple IMUs on a rigid body are leveraged to provide relative updates, which in turn aids in the estimation of the individual biases and scale-factors. Developed algorithms will be validated through simulation and actual measurements using low-cost IMUs.
Anti-tank (AT) landmines slow down and endanger military advances and present sizeable humanitarian problems. The remediation of these mines by direct human intervention is both dangerous and costly. The Intelligent Systems & Robotics Group (ISRG) at New Mexico Tech has provided a partial solution to this problem by developing an Unmanned Ground Vehicle (UGV) to remediate these mines without endangering human lives. This paper presents an overview of the design and operation of this UGV. Current results and future work are also described herein. To initiate the remediation process the UGV is given the GPS coordinates of previously detected landmines. Once the UGV autonomously navigates to an acceptable proximity of the landmine, a remote operator acquires control over a wireless network link using a joystick on a base station. Utilizing two cameras mounted on the UGV, the operator is able to accurately position the UGV directly over the landmine. The UGV houses a self-contained drill system equipped with its own processing resources, sensors, and actuators. The drill system deploys a neutralizing device over the landmine to neutralize it. One such device, developed by Science Applications International Corporation (SAIC), employs incendiary materials to melt through the container of the landmine and slowly burn the explosive material, thereby safely and remotely disabling the landmine.
Simple radio control cars commonly sold as toys can provide a viable starting platform for the development of low-cost intelligent Unmanned Ground Vehicles (UGVs) for the study of robot collectives. In a collaborative effort, Sandia National Labs and New Mexico Tech have successfully demonstrated proof-of-concept by utilizing low-cost radio control cars manufactured by Nikko. Initial tests have involved using a small number (two to ten) of these UGVs to successfully demonstrate both collaborative and independent behavior simultaneously. In the tests individuals share their locations with the collective to cover an area, thus demonstrating collaborative behavior. Independent behavior is demonstrated as each member of the collective maintains a desired compass heading while simultaneously avoiding obstacles in its path. These UGVs are powered by high-capacity rechargeable batteries and equipped with a custom-designed microcontroller board with a stackable modular interface and wireless communication. The initial modular sensor configuration includes a digital compass and GPS unit for navigation as well as ultrasonic sensors for obstacle avoidance. This paper describes the design and operations of these UGVs, their possible uses, and the advantages of using a radio control car platform as a low-cost starting point for the development of intelligent UGV collectives.
In this paper, a brief overview of the power control problem will be presented along with different directions in power control design. In addition, a new approach to power control design inspired from control theory will be introduced. In this approach, linear quadratic control will be utilized to determine the transmission power of each node in the network. The system states will represent the signal quality and the error between the signal-to-interference level and the desired target. The necessary modifications to the IEEE 802.11 MAC layer to incorporate the proposed power control algorithm will be described.
In this paper, a new formulation for the parametric active contour
model is presented. The new formulation is based on statistical
pattern recognition theory. A hybrid of kernel density estimation
and fuzzy logic is used to show that active contours can be
thought of as a pattern recognition problem. The proposed approach
is used in two different application domains, with different
performance requirements, to demonstrate its effectiveness. First,
the proposed approach is used for a magnetic resonance image
segmentation problem to demonstrate the segmentation accuracy.
Second, the contour is used in a target tracking experiment to
show its tracking capabilities.
This paper presents a comprehensive review of the published algorithms on power control for cellular systems. The majority of the research is focused on Code Division Multiple Access (CDMA) systems, although a small fraction of the reviewed literature pertains to Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA).
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