Learning Task Constraints from Demonstration for Hybrid Force/Position Control

We present a novel method for learning hybrid force/position control from demonstration. We learn a dynamic constraint frame aligned to the direction of desired force using Cartesian Dynamic Movement Primitives. In contrast to approaches that utilize a fixed constraint frame, our approach easily accommodates tasks with rapidly changing task constraints over time. We activate only one degree of freedom for force control at any given time, ensuring motion is always possible orthogonal to the direction of desired force. Since we utilize demonstrated forces to learn the constraint frame, we are able to compensate for forces not detected by methods that learn only from the demonstrated kinematic motion, such as frictional forces between the end-effector and the contact surface. We additionally propose novel extensions to the Dynamic Movement Primitive (DMP) framework that encourage robust transition from free-space motion to in-contact motion in spite of environment uncertainty. We incorporate force feedback and a dynamically shifting goal to reduce forces applied to the environment and retain stable contact while enabling force control. Our methods exhibit low impact forces on contact and low steady-state tracking error.Comment: Under revie

Machinima And Video-based Soft Skills Training

Multimedia training methods have traditionally relied heavily on video based technologies and significant research has shown these to be very effective training tools. However production of video is time and resource intensive. Machinima (pronounced \u27muh-sheen-eh-mah\u27) technologies are based on video gaming technology. Machinima technology allows video game technology to be manipulated into unique scenarios based on entertainment or training and practice applications. Machinima is the converting of these unique scenarios into video vignettes that tell a story. These vignettes can be interconnected with branching points in much the same way that education videos are interconnected as vignettes between decision points. This study addressed the effectiveness of machinima based soft-skills education using avatar actors versus the traditional video teaching application using human actors. This research also investigated the difference between presence reactions when using avatar actor produced video vignettes as compared to human actor produced video vignettes. Results indicated that the difference in training and/or practice effectiveness is statistically insignificant for presence, interactivity, quality and the skill of assertiveness. The skill of active listening presented a mixed result indicating the need for careful attention to detail in situations where body language and facial expressions are critical to communication. This study demonstrates that a significant opportunity exists for the exploitation of avatar actors in video based instruction

Gender-bias and its influence on the accuracy of eyewitness identification of perpetrators

Previous research has looked at how eyewitnesses can identify characteristically with victims of crimes, but few have looked at how eyewitnesses identify with the perpetrators in any capacity (Block, Greenberg, & Goodman, 2009). More specifically, few have looked at how gender-bias influences eyewitness identification of the perpetrator and characteristics (Butts, Mixon, Mulekar , & Bringmann, 1995; Wright & Sladden, 2003). The purpose of the current research was to look directly at how gender influenced the accuracy of eyewitness identification of a perpetrator. It was hypothesized that women would remember more details about a female perpetrator than a male perpetrator, and conversely, males would remember more details about a male perpetrator than a female perpetrator. It was also hypothesized that females would be overall more accurate than male participants. Participants were 165 college students volunteering in exchange for research credit. Participants observed a staged crime via recording while engaging in a monitoring task and completed measures of intelligence, demographic information, and trauma history as well as identifying information for perpetrators. Results were non- significant as to whether or not females are more accurate or have better recall of details but the results do have impact for future research; particularly in how vigilance can impact the accuracy of detailed recall --Leaf iv

Active Learning of Probabilistic Movement Primitives

A Probabilistic Movement Primitive (ProMP) defines a distribution over trajectories with an associated feedback policy. ProMPs are typically initialized from human demonstrations and achieve task generalization through probabilistic operations. However, there is currently no principled guidance in the literature to determine how many demonstrations a teacher should provide and what constitutes a "good'" demonstration for promoting generalization. In this paper, we present an active learning approach to learning a library of ProMPs capable of task generalization over a given space. We utilize uncertainty sampling techniques to generate a task instance for which a teacher should provide a demonstration. The provided demonstration is incorporated into an existing ProMP if possible, or a new ProMP is created from the demonstration if it is determined that it is too dissimilar from existing demonstrations. We provide a qualitative comparison between common active learning metrics; motivated by this comparison we present a novel uncertainty sampling approach named "Greatest Mahalanobis Distance.'' We perform grasping experiments on a real KUKA robot and show our novel active learning measure achieves better task generalization with fewer demonstrations than a random sampling over the space.Comment: Under revie

Homes for hunters?: Exploring the concept of home at hunter-gatherer sites in upper paleolithic Europe and epipaleolithic Southwest Asia

In both Southwest Asia and Europe, only a handful of known Upper Paleolithic and Epipaleolithic sites attest to aggregation or gatherings of hunter-gatherer groups, sometimes including evidence of hut structures and highly structured use of space. Interpretation of these structures ranges greatly, from mere ephemeral shelters to places “built” into a landscape with meanings beyond refuge from the elements. One might argue that this ambiguity stems from a largely functional interpretation of shelters that is embodied in the very terminology we use to describe them in comparison to the homes of later farming communities: mobile hunter-gatherers build and occupy huts that can form campsites, whereas sedentary farmers occupy houses or homes that form communities. Here we examine some of the evidence for Upper Paleolithic and Epipaleolithic structures in Europe and Southwest Asia, offering insights into their complex “functions” and examining perceptions of space among hunter-gatherer communities. We do this through examination of two contemporary, yet geographically and culturally distinct, examples: Upper Paleolithic (especially Magdalenian) evidence in Western Europe and the Epipaleolithic record (especially Early and Middle phases) in Southwest Asia. A comparison of recent evidence for hut structures from these regions suggests several similarities in the nature of these structures, their association with activities related to hunter-gatherer aggregation, and their being “homes” imbued with quotidian and symbolic meaning

Three-dimensional microfabrication through a multimode optical fiber

Additive manufacturing, also known as 3D printing, is an advanced manufacturing technique that allows the fabrication of arbitrary macroscopic and microscopic objects. All 3D printing systems require large optical elements or nozzles in proximity to the built structure. This prevents their use in applications in which there is no direct access to the area where the objects have to be printed. Here, we demonstrate three-dimensional microfabrication based on two-photon polymerization (TPP) with sub diffraction-limited resolution through an ultra-thin, 50 mm long printing nozzle of 560 micrometers in diameter. Using wavefront shaping, femtosecond infrared pulses are focused and scanned through a multimode optical fiber (MMF) inside a photoresist that polymerizes via two-photon absorption. We show the construction of arbitrary 3D structures of 500 nm resolution on the other side of the fiber. To our knowledge, this is the first demonstration of microfabrication through a multimode optical fiber. Our work represents a new area which we refer to as endofabrication

Optimism and Performance of Novice ESOL Teachers

The aim of this study is to examine the relationship between gender, optimism and perceived teaching performance amongst novice ESOL teachers. Graduates from two hybrid TESOL programs (N=47) were sampled and surveyed. Optimism significantly predicted perceived teaching performance, t(43)= 3.17, p=.003, and there was marginal association between gender and perceived teaching performance, t(43)= -1.92, p=.06. Further analyses indicated that the mean ratings of teaching performance were significantly different between men and women F(1,45)= 5.12, p=.03. In sum, our results suggest that gender and optimism are factors in perceptions of teacher efficacy amongst novice ESOL teachers

Mechanism of skyrmion condensation and pairing for twisted bi-layer graphene

When quantum flavor Hall insulator phases of itinerant fermions are disordered by strong quantum fluctuations, the condensation of skyrmion textures of order parameter fields can lead to superconductivity. In this work, we address the mechanism of skyrmion condensation by considering the scattering between (2+1)-dimensional, Weyl fermions and hedgehog type tunneling configurations of order parameters that violate the skyrmion-number conservation law. We show the quantized, flavor Hall conductivity ($\sigma^f_{xy}$) controls the degeneracy of topologically protected, fermion zero-modes, localized on hedgehogs, and the overlap between zero-mode eigenfunctions or 't Hooft vertex determines the nature of pairing. We demonstrate the quantum-disordered, flavor Hall insulators with $\sigma^f_{xy}= 2 N$ lead to different types of charge $2 N e^-$ superconductivity. Some implications for the competition among flavor Hall insulators, the charge $2e^-$ paired states in BCS and pair-density-wave channels, and the composite, charge $4e^-$ superconductors for twisted bilayer graphene are outlined.Comment: 8 pages, 1 figur