Electrical Engineering and Computer Science

This paper argues that the S* robot control architecture of Tsotsos [1997] is well suited to intelligent control of planetary rovers. Behaviour-based systems 0perate well in unknown environments, but cannot support deliberative functionality. Hybrid systems resolve this issue, but introduce the potential for other problems. S* is a non-hybrid approach that supports deliberation but also attentive vision. As well, S* includes a missionspecification language that permits behaviour reconfiguration on the fly.

In an ongoing project, we aim at assisting disabled children at play. To this end, we are developing a semi autonomous robotic wheelchair. It is equipped with several visual sensors and a robotic manipulator and thus conveniently enhances the innate capabilities of a disabled child. In addition to a touch screen, the child may control the wheelchair using simple head movements. As control based on head posture requires reliable face detection and head pose recognition, we are in need of a robust technique that may effortlessly be tailored to individual users. In this paper, we present a multilinear classification algorithm for fast and reliable face detection. It trains within seconds and thus can easily be customized to the home environment of a disabled child. Subsequent head pose recognition is done using support vector machines. Experimental results show that this two stage approach to head pose-based robotic wheelchair control performs fast and very robust.

While current robot middleware projects address functional concerns of robot control, middleware should also support the needs of task-directed perceptual processing. S* is an approach to intelligent control that addresses this concern in particular. It prescribes constructing intelligent controllers as behaviour-based systems augmented with shared representations, which supports task-directed perception and also enables the development of extensible controllers. The focus of this paper is on a software framework, developed to support the development of intelligent robot control systems by teams of designers.

In images of real visual scenes, contours are often fragmented by occlusion, shadows and low re ectance contrast. In order to infer shape from contour, the human visual system must selectively integrate fragments projecting from a common object while keeping fragments from di erent objects separate. In a previous paper we showed that contour closure has a strong in uence on the speed of this process. In this paper we employ a visual search method to evaluate potential measures for the perceptual closure of fragmented shapes. We show that while certain intuitive measures are psychophysically inconsistent, a measure based on the L 2 norm of the lengths of contour gaps is appropriate for both polygonal and smooth shapes in that response time can be expressed as a function of this measure. The L 2 norm is shown to emphasize large gaps relative to small, and to embody a principle of perceptual regularity. Our results also have implications for the shape of perceptually natural contour interpolants.

An outline drawing often serves as an excellent depiction of a visual scene. Somehow, our visual system can form two-and tbreedimensional percepts solely from onedimeosional contour information. In ma~mati~, contour &sure plays a key role ia bridging this ~~io~~ gap, however in perceptions the link between closure and shape is unclear. To better understand this relatiousbip, we devised a set of visual search experiments in which subjects discriminate outline figures by meaus of their two-dimensional shape. By modulating the degree of closure of the outlines, we show that two-~me~ional shape processiu g is rapid for closed stimuli but slow for open stbnuli. We further show that search can be characterized as a smooth, monotonic function of the degree of closure, supporting the notion of a perceptual closure continuum. Contour Shape Topology Perceptual organization Visual search CONTOUR CLOSURE AND DISCRIMINATION 983

We used a visual-search method to investigate the role of shadows in the rapid discrimination of scene properties. Targets and distractors were light or dark 2-D crescents of identical shape and size, on a mid-grey background. From the dark stimuli, illusory 3-D shapes can be created by blurring one arc of the crescent. If the inner arc is blurred, the stimulus is perceived as a curved surface with attached shadow. If the outer arc is blurred, the stimulus is perceived as a flat surface casting a shadow. In a series of five experiments, we used this simple stimulus to map out the shadow properties that the human visual system can rapidly detect and discriminate. To subtract out 2-D image factors, we compared search performance for dark-shadow stimuli with performance for light-shadow stimuli which generally do not elicit strong 3-D percepts. We found that the human visual system is capable of rapid discrimination based upon a number of different shadow properties, including the type...

Real-time monitoring system µPMU hardware and software design Error and phasor estimation Computational time minimization This article presents a roadmap for distribution grid µPMU hardware and software design consideration and implantation to ensure high performance within limited computational time of sampling frequency 512 samples/cycle. A proposed 12 channels, multi-voltage level µPMU hardware and rules of voltage and current transducer, analog filter, analog-to-digital converter, sampling rate definition, and PCB design and selection are presented. From the software view, software minimization procedures are implemented to reduce the estimation time of the proposed µPMU to 18 µsec under high sampling frequency operation. Additionally, error estimation and compensation are used to ensure robust performance, while the computational burden of the error compensation stage is reduced by Taylor series linearization. The proposed µPMU is designed to provide traditional phasor, frequency and harmonics measurements besides a point-on-wave under dynamic operation mode. The proposed device is tested under IEEE Std C37. 118.1 and 118.2 and showed accurate phasor estimation up to 0.03% for the magnitude and angle accuracy up to 0.0036 o , while the frequency is estimated with maximum variation of 0.032% under dynamic operation.

In this paper we investigate automated theorem proving systems represented as finite classes of resolution proof systems. We call such classes resolution approximations. For many first-order logics, theorem proving based on such representation offers a substantial saving of computer time. We show that minimal resolution approximations of finitely-valued first-order logics can be effectively constructed.

The properties of monotonic inference systems and the properties of their theories are strongly linked. These links, however, are much weaker in nonmonotonic inference systems. In this paper we introduce the notion of an axiomatic variety for a theory and show how this notion, instead of the notion of a theory, can be used for the syntactic and semantic analysis of nonmonotonic inferences.

Inkjet printing is a promising technique for printed micro-electronics due to low cost, customizability and compatibility with large-area, flexible substrates. However, printed line shapes can suffer from bulges at the start of lines and at corner points in 2D line patterns. The printed pattern can be multiple times wider than the designed linewidth. This can severely impact manufacturing accuracy and achievable circuit density. Bulging can be difficult to prevent without changing the ink-substrate-system, the drying conditions or the circuit design, all of which can be undesirable. Here, we demonstrate a novel printing methodology that solves this issue by changing the order in which drops are placed on the substrate. The pattern is split up into segments of three drops where the central drop is printed last. This symmetric printing prevents the unwanted ink flow that causes bulging. Larger bulge-free patterns are created by successively connecting segments. Line formation in both ...

Hybrid organic/inorganic solar cells have been fabricated and studied. The aim being to take advantage of the beneficial properties of both organic and inorganic materials. In this work we studied hybrid n-GaAs/Polymer photovoltaic devices and the effects of adding either carbon nanotubes or graphene into the polymer layer (either poly (3,4-ethyldioxythiophene):poly (styrenesulfunate) (PEDOT:PSS) or polyaniline (PANI)) to enhance its conductivity. We also investigated the use of two different metals (Al or Ag) as the anode electrode material to determine the influence of metal atoms migrating into the polymer layer on solar cell efficiency. The devices with the structure Al/PEDOT:PSS:MWCNT/n-GaAs/Au:Ge/Ni/Au exhibited the best performance, with a short circuit current (Jsc) of 28.6 mA/cm2 , an open circuit voltage (Voc) of 0.51 V, a fill factor (FF) of 29.8% and a power conversion efficiency (PCE) of 4.41% which is higher than other inorganic/organic hybrid devices reported in the literature. Based on optical absorption measurements and SEM analysis the solar cell performances reported here can mainly be attributed to photon absorption in both the doped PEDOT:PSS and the GaAs layers resulting in an increase of electron-hole pairs and improved the efficiency of the solar cells containing PEDOT:PSS in comparison with those containing PANI.