Evaluation of telerobotic systems using an instrumented task board

An instrumented task board was developed at NASA Marshall Space Flight Center (MSFC). An overview of the task board design, and current development status is presented. The task board was originally developed to evaluate operator performance using the Protoflight Manipulator Arm (PFMA) at MSFC. The task board evaluates tasks for Orbital Replacement Unit (ORU), fluid connect and transfers, electrical connect/disconnect, bolt running, and other basic tasks. The instrumented task board measures the 3-D forces and torques placed on the board, determines the robot arm's 3-D position relative to the task board using IR optics, and provides the information in real-time. The PFMA joint input signals can also be measured from a breakout box to evaluate the sensitivity or response of the arm operation to control commands. The data processing system provides the capability for post processing of time-history graphics and plots of the PFMA positions, the operator's actions, and the PFMA servo reactions in addition to real-time force/torque data presentation. The instrumented task board's most promising use is developing benchmarks for NASA centers for comparison and evaluation of telerobotic performance

Singular Solutions in Problems of Optimal Control

The contribution of this thesis is the somewhat general analysis, of singular solutions which arise in problems of optimal control and the development of certain analytical procedures for detecting and calculating singular solutions. The basic optimal control problem considered in this study is the task of choosing a control u(t) which will a) transfer the state of a system, described by the a first order ordinary differential equations, from some prescribed initial state to some prescribed final (terminal) state and b) simultaneously minimize (with respect to the control u) an index of performance J of the form. It is assumed that the allowable values, of the control .u may be constrained to lie in some set U. The conventional mathematical techniques presently being used in optimal control theory are discussed. It is shown that for a certain class of optimal control problems, which are characterized by the control u appearing linearly in the system state equations (l) and the integrand of the index of performance (2), the optimal control u*(t) is found (formally) to the of the bang-bang type In (3), A and B are, respectively, the upper and lower hounds on the admissible control u and F(t) is a certain function of time which is called the switching function. When the switching function becomes identically zero over a finite time interval the conventional mathematical \u27techniques fail to yield any information about the desired optimal control. The solution in this ease is said to he singular and the corresponding control is termed singular control . The nature of singular solutions is being investigated in detail and the apparent failure of the conventional mathematical techniques has been shown to be due to the fact that singular optimal controls lie in the interior (rather than on the boundary) of the admissible set U. The concept of a singular control surface in the system state space was introduced and is used to examine the geometry of singular solutions. Some mathematical properties of the singular control surface are being derived and a backward tracing scheme is used to aid in establishing the role of singular sub-arcs in the solution of optimal control problems. It is being shown that the singular control u*(t) can be obtained from the condition F(t) O and in some cases can be synthesized as a function of the system state variables. The proposed techniques for solving optimal control problems with singular solutions can be illustrated by means of four examples which are worked out in detail

Conformational Preferences of cis-1,3-Cyclopentanedicarboxylic Acid and Its Salts by ^1H NMR Spectroscopy: Energetics of Intramolecular Hydrogen Bonds in DMSO

The conformational populations of cis-1,3- cyclopentanedicarboxylic acid (1) and its mono- and dianion were established in DMSO solution by comparing the vicinal proton−proton coupling constants (^3JHH) obtained in solution to their theoretical counterparts. Geometries used for ^3JHH theoretical estimation (using Karplus-type equations) were obtained from optimized structures at the B3LYP/6-31G-(2d,2p) level. The diacid (1) adopted many conformations, whereas the ionized species (1A mono- and 1B dianion) assumed single conformations. A downfield chemical shift of 19.45 ppm (Δδ_H = 7.43 ppm) observed at −60 °C was indicative of intramolecular hydrogen bonding in 1A, which was later corroborated by determining the ratio of the first (K_1) to the second (K_2) ionization constants. K_1/K_2 in DMSO (1.3 × 10^7) was significantly larger than the value in water (2 × 10). In addition, K_1/K_E = 200 (where K_E is the acidity constant of the monomethylester of 1) was greater than the intramolecular hydrogen bonding threshold value of 2. The calculated intramolecular hydrogen bond strength of 1A was ∼3.1 kcal mol^(−1), which is ∼2.7 kcal mol^(−1) more stable than the values for cis- 1,3-cyclohexanedicarboxylic acid (2A). Thus, the relative energies of intramolecular hydrogen bonding in the monoanions 1A and 2A suggests that 1,3-diaxial conformers are more favored for cyclopentane than for cyclohexane rings

Persistent virtual identity in community networks: Impact to social capital value chains

Community networks are digital infrastructures designed to strengthen bonds and build social capital between members of a community, facilitating accomplishment of goals. As we consider how community network implementations can be improved, we recognize the potential that social translucence and activity notification introduces to other forms of CSCW. We investigate how the underlying notion of persistent virtual identity---established at logon---impacts user perception of community networks and their social capital production process. To approach this question, we introduce a design model that reconciles various computer-mediated communication research contributions with support for typical community network scenarios of use. Using this model, we perform an inspection on existing community network implementations. Based on the insight gained through this analysis, we introduce a generic prototype that allows survey of user reaction to community network design elements under differing conditions of persistent virtual identity implementation and usage motivation---the results frame a value-chain understanding of conceptual tradeoffs

E-resource Renewal Awareness: Using Google Calendar to Bring Selectors on Board

This poster session provides an example of how Google Calendar can be utilized to facilitate the timely and productive assessment of subscription e-resources. At Columbia University Libraries, we have constructed a program that feeds acquisitions data from our library management system into our shared Google Calendar. For each fund code, a calendar is generated, listing each payment as an event and following that event by reminders that occur at predetermined intervals prior to the next renewal date. By streaming renewal information into a familiar and user-friendly system, we are aiming to promote widespread librarian involvement in the process of timely e-resource assessment. The coding used to feed acquisitions data into Google Calendar was worked out by Nada O'Neal and is available at: https://github.com/nadaoneal/gapps_python_whatever

Assessing Ongoing Electronic Resource Purchases: Linking Tools to Synchronize Staff Workflows

Ongoing electronic resource purchases represent a substantial proportion of collections budgets. Recognizing the necessity of systematic ongoing assessment with full selector engagement, Columbia University Libraries appointed an Electronic Resources Assessment Working Group to promote the inclusion of such resources within our current culture of assessment. This article describes the Working Group’s implementation of an electronic resource renewal reminder system in Google Calendar, a calendar already in use by selectors for daily scheduling. In discussing this particular solution, this article shows how libraries can link existing systems together to move beyond their limitations and integrate them into existing staff workflows

Model Systems for the Study of Kidney Development: Use of the Pronephros in the Analysis of Organ Induction and Patterning

AbstractMost vertebrate organs, once formed, continue to perform the function for which they were generated until the death of the organism. The kidney is a notable exception to this rule. Vertebrates, even those that do not undergo metamorphosis, utilize a progression of more complex kidneys as they grow and develop. This is presumably due to the changing conditions to which the organism must respond to retain what Homer Smith referred to as our physiological freedom. To quote, “Recognizing that we have the kind of blood we have because we have the kind of kidneys we have, we must acknowledge that our kidneys constitute the major foundation of our physiological freedom. Only because they work the way they do has it become possible for us to have bones, muscles, glands, and brains. Superficially, it might be said that the function of the kidneys is to make urine; but in a more considered view one can say that the kidneys make the stuff of philosophy itself” (“From Fish to Philosopher,” Little, Brown and Co., Boston, 1953). Different kidneys are used to make the stuff of philosophy at different stages of development depending on the age and needs of the organism, rather than the usual approach of simply making embryonic organs larger as the animal grows. Although evolution has provided the higher vertebrates with complex adult kidneys, they continue to utilize simple kidneys in embryogenesis. In lower vertebrates with simple adult kidneys, even more simple versions are used during early developmental stages. In this review the anatomy, development, and gene expression patterns of the embryonic kidney, the pronephros, will be described and compared to the more complex kidney forms. Despite some differences in anatomy, similar developmental pathways seem to be responsible for the induction and the response to induction in both evanescent and permanent kidney forms. Gene expression patterns can, therefore, be added to the morphological and functional data indicating that all forms of the kidney are closely related structures. Given the similarities between the development of simple and complex kidneys, the embryonic kidneys may be an ideal model system in which to investigate the genesis of multicomponent organ systems