The acquisition of inductive constraints

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 197-216).Human learners routinely make inductive inferences, or inferences that go beyond the data they have observed. Inferences like these must be supported by constraints, some of which are innate, although others are almost certainly learned. This thesis presents a hierarchical Bayesian framework that helps to explain the nature, use and acquisition of inductive constraints. Hierarchical Bayesian models include multiple levels of abstraction, and the representations at the upper levels place constraints on the representations at the lower levels. The probabilistic nature of these models allows them to make statistical inferences at multiple levels of abstraction. In particular, they show how knowledge can be acquired at levels quite remote from the data of experience--levels where the representations learned are naturally described as inductive constraints. Hierarchical Bayesian models can address inductive problems from many domains but this thesis focuses on models that address three aspects of high-level cognition. The first model is sensitive to patterns of feature variability, and acquires constraints similar to the shape bias in word learning. The second model acquires causal schemata--systems of abstract causal knowledge that allow learners to discover causal relationships given very sparse data. The final model discovers the structural form of a domain--for instance, it discovers whether the relationships between a set of entities are best described by a tree, a chain, a ring, or some other kind of representation. The hierarchical Bayesian approach captures several principles that go beyond traditional formulations of learning theory.(cont.) It supports learning at multiple levels of abstraction, it handles structured representations, and it helps to explain how learning can succeed given sparse and noisy data. Principles like these are needed to explain how humans acquire rich systems of knowledge, and hierarchical Bayesian models point the way towards a modern learning theory that is better able to capture the sophistication of human learning.by Charles Kemp.Ph.D

Visual Estimation of Fingertip Pressure on Diverse Surfaces using Easily Captured Data

People often use their hands to make contact with the world and apply pressure. Machine perception of this important human activity could be widely applied. Prior research has shown that deep models can estimate hand pressure based on a single RGB image. Yet, evaluations have been limited to controlled settings, since performance relies on training data with high-resolution pressure measurements that are difficult to obtain. We present a novel approach that enables diverse data to be captured with only an RGB camera and a cooperative participant. Our key insight is that people can be prompted to perform actions that correspond with categorical labels describing contact pressure (contact labels), and that the resulting weakly labeled data can be used to train models that perform well under varied conditions. We demonstrate the effectiveness of our approach by training on a novel dataset with 51 participants making fingertip contact with instrumented and uninstrumented objects. Our network, ContactLabelNet, dramatically outperforms prior work, performs well under diverse conditions, and matched or exceeded the performance of human annotators

Visual Odometry and Control for an Omnidirectional Mobile Robot with a Downward-Facing Camera

©2010 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.DOI: 10.1109/IROS.2010.5649749Presented at the 2010 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 18-22 Oct. 2010, Taipei.An omnidirectional Mecanum base allows for more flexible mobile manipulation. However, slipping of the Mecanum wheels results in poor dead-reckoning estimates from wheel encoders, limiting the accuracy and overall utility of this type of base. We present a system with a downwardfacing camera and light ring to provide robust visual odometry estimates. We mounted the system under the robot which allows it to operate in conditions such as large crowds or low ambient lighting. We demonstrate that the visual odometry estimates are sufficient to generate closed-loop PID (Proportional Integral Derivative) and LQR (Linear Quadratic Regulator) controllers for motion control in three different scenarios: waypoint tracking, small disturbance rejection, and sideways motion. We report quantitative measurements that demonstrate superior control performance when using visual odometry compared to wheel encoders. Finally, we show that this system provides highfidelity odometry estimates and is able to compensate for wheel slip on a four-wheeled omnidirectional mobile robot base

Cellular Models of Aggregation-Dependent Template-Directed Proteolysis to Characterize Tau Aggregation Inhibitors for Treatment of Alzheimer's Disease

Copyright © 2015, The American Society for Biochemistry and Molecular Biology. Acknowledgements-We thank Drs Timo Rager and Rolf Hilfiker (Solvias, Switzerland) for polymorph analyses.Peer reviewedPublisher PD

Human-Robot Interaction Studies for Autonomous Mobile Manipulation for the Motor Impaired

©2009, Association for the Advancement of Artificial Intelligence (www.aaai.org). The original publication is available at : http://www.aaai.org/Papers/Symposia/Spring/2009/SS-09-03/SS09-03-003.pdf.Presented at Experimental Design for Real-World Systems, AAAI Spring Symposium, March 23-25, 2009 at Stanford University, Stanford, California USA.We are developing an autonomous mobile assistive robot named El-E to help individuals with severe motor impairments by performing various object manipulation tasks such as fetching, transporting, placing, and delivering. El-E can autonomously approach a location specified by the user through an interface such as a standard laser pointer and pick up a nearby object. The initial target user population of the robot is individuals suffering from amyotrophic lateral sclerosis (ALS). ALS, also known as Lou Gehrig’s disease, is a progressive neuro-degenerative disease resulting in motor impairments throughout the entire body. Due to the severity and progressive nature of ALS, the results from developing robotic technologies to assist ALS patients could be applied to wider motor impaired populations. To accomplish successful development and real world application of assistive robot technology, we have to acquire familiarity with the needs and everyday living conditions of these individuals. We also believe the participation of prospective users throughout the design and development process is essential in improving the usability and accessibility of the robot for the target user population. To assess the needs of prospective users and to evaluate the technology being developed, we applied various methodologies of human studies including interviewing, photographing, and conducting controlled experiments. We present an overview of research from the Healthcare Robotics Lab related to patient needs assessment and human experiments with emphasis on the methods of human centered approach

Tactile Sensing over Articulated Joints with Stretchable Sensors

©2013 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.Presented at the World Haptics Conference (WHC), 2013, 14-17 April 2013.DOI: 10.1109/WHC.2013.6548392Biological organisms benefit from tactile sensing across the entire surfaces of their bodies. Robots may also be able to benefit from this type of sensing, but fully covering a robot with robust and capable tactile sensors entails numerous challenges. To date, most tactile sensors for robots have been used to cover rigid surfaces. In this paper, we focus on the challenge of tactile sensing across articulated joints, which requires sensing across a surface whose geometry varies over time. We first demonstrate the importance of sensing across joints by simulating a planar arm reaching in clutter and finding the frequency of contact at the joints. We then present a simple model of how much a tactile sensor would need to stretch in order to cover a 2 degree-of-freedom (DoF) wrist joint. Next, we describe and characterize a new tactile sensor made with stretchable fabrics. Finally, we present results for a stretchable sleeve with 25 tactile sensors that covers the forearm, 2 DoF wrist, and end effector of a humanoid robot. This sleeve enabled the robot to reach a target in instrumented clutter and reduce contact forces

Out-of-band exposure characterization with the SEMATECH Berkeley 0.3-NA microfield exposure tool

For the commercialization of extreme ultraviolet lithography (EUVL), discharge or laser produced, pulsed plasma light sources are being considered. These sources are known to emit into a broad range of wavelengths that are collectively referred to as the out-of-band (OOB) radiation by lithographers. Multilayer EUV optics reflect OOB radiation emitted by the EUV sources onto the wafer plane resulting in unwanted background exposure of the resist (flare) and reduced image contrast. The reflectivity of multilayer optics at the target wavelength of 13.5 nm is comparable to that of their reflectivity in the deep ultraviolet (DUV) and UV regions from 100-350 nm. The aromatic molecular backbones of many of the resists used for EUV are equally absorptive at specific DUV wavelengths as well. In order to study the effect of these wavelengths on imaging performance in a real system, we are in the process of integrating a DUV source into the SEMATECH Berkeley 0.3-NA Microfield Exposure Tool (MET). The MET plays an active role in advanced research in resist and mask development for EUVL and as such, we will utilize this system to systematically evaluate the imaging impact of DUV wavelengths in a EUV system. In this paper, we present the optical design for the new DUV component and the simulation-based imaging results predicting the potential impact of OOB based on known resist, mask, and multilayer conditions. It should be noted that because the projection optics work equally well as imaging optics at DUV wavelengths, the OOB radiation cannot be treated simply as uniform background or DC flare

Hand It Over or Set It Down: A User Study of Object Delivery with an Assistive Mobile Manipulator

©2009 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.Presented at The 18th IEEE International Symposium on Robot and Human Interactive Communication, Sept. 27 2009-Oct. 2 2009, Toyama.Delivering an object to a user would be a generally useful capability for service robots. Within this paper, we look at this capability in the context of assistive object retrieval for motor-impaired users. We first describe a behavior-based system that enables our mobile robot EL-E to autonomously deliver an object to a motor-impaired user. We then present our evaluation of this system with 8 motor-impaired patients from the Emory ALS Center. As part of this study, we compared handing the object to the user (direct delivery) with placing the object on a nearby table (indirect delivery). We tested the robot delivering a cordless phone, a medicine bottle, and a TV remote, which were ranked as three of the top four most important objects for robotic delivery by ALS patients in a previous study. Overall, the robot successfully delivered these objects in 126 out of 144 trials (88%) with a success rate of 97% for indirect delivery and 78% for direct delivery. In an accompanying survey, participants showed high satisfaction with the robot with 4 people preferring direct delivery and 4 people preferring indirect delivery. Our results indicate that indirect delivery to a surface can be a robust and reliable delivery method with high user satisfaction, and that robust direct delivery will require methods that handle diverse postures and body types

EUV mask reflectivity measurements with micro-scale spatial resolution

The effort to produce defect-free mask blanks for EUV lithography relies on increasing the detection sensitivity of advanced mask inspection tools, operating at several wavelengths. They describe the unique measurement capabilities of a prototype actinic (EUV) wavelength microscope that is capable of detecting small defects and reflectivity changes that occur on the scale of microns to nanometers. The defects present in EUV masks can appear in many well-known forms: as particles that cause amplitude or phase variations in the reflected field; as surface contamination that reduces reflectivity and contrast; and as damage from inspection and use that reduces the reflectivity of the multilayer coating. This paper presents an overview of several topics where scanning actinic inspection makes a unique contribution to EUVL research. They describe the role of actinic scanning inspection in defect repair studies, observations of laser damage, actinic inspection following scanning electron microscopy, and the detection of both native and programmed defects

Data Recovery Investigations: Murvaul Creek Site (41PN175), Panola County, Texas

This report summarizes the archeological findings of the 2011 data recovery investigations at the Murvaul Creek site, 41PN175, in far northeastern Texas in Panola County. The site is located along Farm-to-Market Road (FM) 10 approximately 1 mile north of Gary, Texas (Figure 1). Geo-Marine, Inc. (GMI), performed this work under contract to the Texas Department of Transportation, Environmental Affairs Division (TxDOT ENV) under the Texas Antiquities Permit Number 5879 (Work Authorization [WA] 579 06 SA005; WA 590 08 SA005; CSJ:1222-01-014; Geo-Marine project numbers 22005.00.06 and 22005.00.09). The fieldwork for this project was conducted in advance of the planned widening of FM 10 that was to replace three bridges and a culvert over Murvaul Creek with a larger structure and shift the road approximately 26 meters (m; 85 feet [ft]) to the east. Since the planned improvements of FM 10 would result in the loss of information at the Murvaul Creek site—a site that was recommended eligible for inclusion in the National Register of Historic Places (NRHP) and for designation as a State Antiquities Landmark (SAL; formerly State Archeological Landmark)—the current data recovery investigations were initiated. The data recovery investigations were conducted between February 7, 2011, and April 3, 2011. During this period, the fieldwork was conducted in several stages: site clearing, geophysical survey, 50-x-50-centimeter (cm) excavations, block excavations, and mechanical site scraping. With the exception of the site clearing stage, the results of each of the fieldwork stages are reviewed individually in this report. The investigations resulted in the documentation of numerous features that appeared to have been the remains of a small Middle-to-Late Caddo settlement or farmstead situated on the edge of an interfluve south of the Murvaul Creek floodplain. Additionally, materials pertaining to the Archaic period were documented across the site. Although the site has been intensively studied within the TxDOT right-of-way (ROW), both the current investigations and previous work were limited to the ROW (cf. Cliff and Perttula 2002). Hence, the site is very likely larger than has been adequately documented