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At least 55 records · Page 3

The application of active side arm controllers in helicopters

Eurocopter Deutschland (ECD) started simulation trials to investigate the particular problems of Side Arm Controllers (SAC) applied to helicopters. Two simulation trials have been performed. In the first trial, the handling characteristics of a 'passive' SAC and the basic requirements for the application of an 'active' SAC were evaluated in pilot-in-the-loop simulations, performing the tasks in a realistic scenario representing typical phases of a transport mission. The second simulation trial investigated the general control characteristics of the 'active' in comparison to the 'passive' control principle. A description of the SACs developed by ECD and the principle of the 'passive' and 'active' control concept is given, as well as specific ratings for the investigated dynamic and ergonomic parameters effecting SAC characteristics. The experimental arrangements, as well as the trials procedures of both simulation phases, are described and the results achieved are discussed emphasizing the advantages of the 'active' as opposed to the 'passive' SAC concept. This also includes the presentation of some critical aspects still to be improved and proposals to solve them.

Knorr, R.↗

Highlights of the Quad Multilateral Nuclear Arms Control Research Initiative LETTERPRESS Simulation

The US, UK, Sweden and Norway have formed the Quad Nuclear Verification Partnership and have been working together as the ‘Quad’ to ensure non-nuclear weapon states (NNWS) and nuclear weapon states (NWS) participate to overcome the challenge of nuclear arms control verification. The Quad aims to complement and inform the work of other multinational initiatives such as the International Partnership for Nuclear Disarmament Verification (IPNDV). The initial engagement of the Quad was the development and execution of a role-playing, in-field verification simulation, named LETTERPRESS. A benefit of role-playing events is the capacity they have to allow researchers to engage critically with a challenge from multiple perspectives. This paper will introduce LETTERPRESS and the process the Quad followed to develop and execute the multilateral simulation. The paper will highlight the in-play objectives of the verification regime, the site hosting the on-site inspection, and the verification technologies and their roles with respect to the objectives. The paper will include lessons learned from LETTERPRESS, focusing on the in-play objectives and technologies and their contribution to a successful monitoring result. The paper will conclude by highlighting the in-play success of a multilateral verification body and the ability of both NNWS and NWS to contribute to the verification process within LETTERPRESS.

arms control, Quad, LETTERPRESS↗

Developing an intrinsically secure information barrier for arms control verification through machine learning

Near-term solutions are needed to allow for flexible engagement in future nuclear arms control discussions. This project developed a method for implementing an information barrier (IB) on commercial systems, shortening the research and development lifecycle for warhead verification technologies while offering improved and inherently flexible capabilities. The crux of the verification challenge remains the difficulty in developing an authenticatable IB which prevents sensitive host country information from inadvertent transmission to an inspector. Many concepts for IB’s rely on dedicated “trusted” processor modules developed with dedicated custom radiation detection systems and associated algorithms. Without a priori knowledge of the treaty item, the parameter space for measurements can be nearly infinite and robustness against spoofing without the ability to view sensitive data is key. This project has produced an unclassified framework capable of ingesting data from common gamma detectors and identifying the presence of weapons grade nuclear material at over 90% accuracy.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗

Nuclear Arms Control, Nonproliferation, and Counterterrorism: Impacts on Public Health

Reducing the risks of nuclear war, limiting the spread of nuclear weapons and reducing global nuclear weapons stockpiles are key national and international security goals. They are pursued through a variety of international arms control, nonproliferation and counter-terrorism treaties and agreements. These legally binding and political commitments, together with the institutional infrastructure that supports them, work to establish global norms of behavior and have limited the spread of weapons of mass destruction. Beyond the primary security objectives, reducing the likelihood of the use of nuclear weapons, preventing environmental releases of radioactive material, increasing the availability of safe and secure nuclear technology for peaceful purposes, and providing scientific data relevant to predicting and managing the consequences of natural or human-caused disasters world-wide provide significant benefits to global public health.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

Demonstration and Concept of Operations for a Zero-Knowledge Protocol Passive Imaging Measurement for Arms Control

Here, we present an imaging system that employs zero-knowledge protocols to protect sensitive geometrical information, along with procedures to increase confidence in the result. The goal of this work is to enable the inclusion of warhead confirmation measurements in future arms control treaties. We present a demonstration of both true positive and true negative measurements that validate models and establish authenticating procedures toward meeting acceptance requirements for use in nuclear facilities. We use a two-dimensional time-encoded fast neutron imaging system with an anti-symmetric mask pattern; the fast neutron count values exceeding minimum or maximum thresholds indicate that two measured items are not identical. Laboratory measurements over twenty trials show that alarm rates for negative confirmation measurements are within uncertainties of model predictions. Positive confirmation measurements indicate that alarm rates are large enough to encourage treaty compliance.

Sweany, Melinda Dominique [Sandia National Laborat↗

Image-Based Verification Algorithms for Arms Control

PNNL is developing and evaluating radiographic image analysis techniques (active and passive) for verifying sensitive objects in a material control or warhead counting regime in which sensitive information may be acquired and processed behind an information barrier. Since sensitive image information cannot be present outside the information barrier, these techniques are necessary to extract features from the full images and reduce them to relevant parameters (attributes) of the inspected items. This evaluation can be done behind the information barrier, allowing for reporting and storage of non-sensitive attributes only. Several advances have been made to radiographic object verification algorithms, in the areas of spectral imaging for passive detectors and estimation of material density in active radiographic images. Both of these advances are pertinent in an arms control context. While passive radiographic images produced by previous work may be evaluated for the presence of emissive objects, approaches which leverage the spectroscopic potential of the detectors allow a much greater discrimination of SNM from background and other sources. Spectral passive imaging approaches to warhead discrimination and counting include specific materials and geometric arrangement localization, as well as “spectral difference” metrics which group regions with similar spectra together. These approaches may improve resolution for discrimination between materials in addition to locating SNM within surrounding shielding and/or structural elements. Previous work by our group has developed the capability to discern material density and composition in radiographic images by examining the edge transition characteristics of objects. The material construction of an object can be investigated in this way. In a weapons counting or discrimination context, unknown occultation of objects of interest, as well as additional elements of warhead construction, construction materials of varying geometry and makeup and various angles of radiograph are expected to impact algorithm performance. Advances in material discrimination algorithms are presented as a mechanism to help make these approaches robust to these sorts of variations.

Robinson, Sean M.↗

The manned maneuvering unit flight controller arm

The Manned Maneuvering Unit (MMU) and its support equipment provide an extravehicular astronaut mobility, and the ability to work outside the confines of the Shuttle Orbiter payload bay. The MMU design requirements are based on the highly successful Skylab M-509 maneuvering unit. Design of the MMU was started as an R&D effort in April 1975 and Flight Hardware design was started in August 1979 to support a possible requirement for in-space inspection and repair of Orbiter thermal protection tiles. Subsequently, the qualification test and production activities were slowed, and the current projected earliest first flight is now STS-11 in January, 1984. The MMU propulsion subsystem provides complete redundancy with two identical "system". Each system contains a high pressure gaseous nitrogen tank, an isolation valve, a regulator, and twelve 1.7 lbf (7.5 N) thrusters. The thrusters are packaged to provide the crew member six-degree-of-freedom control in response to commands from translational and rotational hand controllers. This paper discusses the MMU control arm requirements, design, and developmental history.

Falkner, K. E.↗

Some piloting experiences with multifunction isometric side-arm controllers in a helicopter

The installation of two side-arm mounted, isometric controllers in the NAE Airborne Simulator, a modified, variable stability Bell 205 A is described, as is the development of various control systems for use with them. The results of two experiments are presented indicating both the feasibility and acceptability of such systems for a wide variety of tasks in a conventional single rotor helicopter, with a minimum of stability augmentation. Areas of future research are indicated.

Morgan, J. M.↗

Dynamic analysis for robot arm control

Explicit state equations provide detailed analytic insight into the dynamic behavior of a robot arm and facilitate the understanding of the control problem. The analytic strength of explicit state equations is exemplified for a given robot arm. In fact, for the quoted example, the explicit and exact state equations involve considerably less computation than the use of the known most efficient general-purpose computational algorithm for robot arm dynamics.

Bejczy, A. K.↗

Test and validation for robot arm control dynamics simulation

The Flight Telerobotic Servicer (FTS) program will require an ability to develop, in a cost effective manner, many simulation models for design, analysis, performance evaluation, and crew training. Computational speed and the degree of modeling fidelity associated with each simulation must be commensurate with problem objectives. To demonstrate evolving state-of-the-art general purpose multibody modeling capabilities, to validate these by laboratory testing, and to expose their modeling shortcomings, two focus problems at the opposite ends of the simulation spectrum are defined: (1) Coarse Acquisition Control Dynamics. Create a real time man-in-the-control-loop simulator. Provide animated graphical display of robot arm dynamics and tactile feedback sufficient for cueing the operator. Interface simulator software with human operated tactile feedback controller; i.e., the Kraft mini-master. (2) Fine, Precision Mode Control Dynamics. Create a high speed, high fidelity simulation model for the design, analysis, and performance evaluation of autonomous 7 degree-of-freedom (DOF) trajectory control algorithms. This model must contain detail dynamic models for all significant dynamics elements within the robot arm, such as joint drive mechanisms.

Yae, K. Harold↗

Effect of motor dynamics on nonlinear feedback robot arm control

A nonlinear feedback robot controller that incorporates the robot manipulator dynamics and the robot joint motor dynamics is proposed. The manipulator dynamics and the motor dynamics are coupled to obtain a third-order-dynamic model, and differential geometric control theory is applied to produce a linearized and decoupled robot controller. The derived robot controller operates in the robot task space, thus eliminating the need for decomposition of motion commands into robot joint space commands. Computer simulations are performed to verify the feasibility of the proposed robot controller. The controller is further experimentally evaluated on the PUMA 560 robot arm. The experiments show that the proposed controller produces good trajectory tracking performances and is robust in the presence of model inaccuracies. Compared with a nonlinear feedback robot controller based on the manipulator dynamics only, the proposed robot controller yields conspicuously improved performance.

Tarn, Tzyh-Jong↗

Towards a mutually reinforcing future : opportunities to integrate nuclear weapons stewardship and arms control objectives.

2010 NPR and President Obama's 2009 Prague Speech highlighted two key objectives with an inherent underlying tension: (1) Moving towards a world free of nuclear weapons; and (2) Sustaining a safe, secure, and effective nuclear arsenal. Objective 1 depends, inter alia, upon reductions in stockpiles at home and abroad and maintaining stability. Objective 2 depends upon needed investments in modernization and life extension. Objectives being pursued predominantly in parallel by largely separate communities.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗

Load balancing and closed chain multiple arm control

The authors give the general dynamical equations for several rigid link manipulators rigidly grasping a commonly held rigid object. It is shown that the number of arm-configuration degrees of freedom lost due to imposing the closed-loop kinematic constraints is the same as the number of degrees of freedom gained for controlling the internal forces of the closed-chain system. This number is equal to the dimension of the kernel of the Jacobian operator which transforms contact forces to the net forces acting on the held object, and it is shown that this kernel can be identified with the subspace of controllable internal forces of the closed-chain system. Control of these forces makes it possible to regulate the grasping forces imparted to the held object or to control the load taken by each arm. It is shown that the internal forces can be influenced without affecting the control of the configuration degrees of freedom. Control laws of the feedback linearization type are shown to be useful for controlling the location and attitude of a frame fixed with respect to the held object, while simultaneously controlling the internal forces of the closed-chain system. Force feedback can be used to linearize and control the system even when the held object has unknown mass properties. If saturation effects are ignored, an unconstrained quadratic optimization can be performed to distribute the load optimally among the joint actuators.

Kreutz, Kenneth↗

Mars Surveyor '98 MVACS Robotic Arm Control System Design Concepts

This paper describes the control system design concepts for the Mars Volatiles and Climate Surveyor (MVACS) Robotic Arm which supports the scientific investigations to be conducted as part of the Mars Surveyor '98 Lander project. Novel solutions are presented to some of the unique problems encountered in this demanding space application with its tight constraints on mass, power, volume, and computing power.

control manipulator Mars robot trajectory 4-DOF↗

Mars Surveyor '98 Landers MVACS Robotic Arm Control System Design Concepts

This paper describes the control system design concepts for the Mars Volatiles and Climate Surveyor (MVACS) Robotic Arm which supports the scientific investigations to be conducted as part of the Mars Surveyor '98 Lander project. Solutions are presented to some of the problems encountered in this demanding space application with its tight constraints on mass, power, volume, and computing resources. Problems addressed include 4-DOF forward and inverse kinematics, trajectory planning to minimize potential impact damage, joint drive train protection, Lander tilt prevention, hardware fault monitoring, and collision avoidance.

Bonitz, Robert G.↗

A physical unclonable neutron sensor for nuclear arms control inspections

Abstract Classical sensor security relies on cryptographic algorithms executed on trusted hardware. This approach has significant shortcomings, however. Hardware can be manipulated, including below transistor level, and cryptographic keys are at risk of extraction attacks. A further weakness is that sensor media themselves are assumed to be trusted, and any authentication and encryption is done ex situ and a posteriori. Here we propose and demonstrate a different approach to sensor security that does not rely on classical cryptography and trusted electronics. We designed passive sensor media that inherently produce secure and trustworthy data, and whose honest and non-malicious nature can be easily established. As a proof-of-concept, we manufactured and characterized the properties of non-electronic, physical unclonable, optically complex media sensitive to neutrons for use in a high-security scenario: the inspection of a military facility to confirm the absence or presence of nuclear weapons and fissile materials.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗