Collaborative design and analysis of electro-optical sensors

A number of disciplines (mechanics, structures, thermal, and optics) are needed to design and build Space Camera. Separate design models are normally constructed by each discipline CAD/CAE tools. Design and analysis is conducted largely in parallel subject to requirements that have been levied on each discipline, and technical interaction between the different disciplines is limited and infrequent. As a result a unified view of the Space Camera design across discipline boundaries is not directly possible in the approach above, and generating one would require a large manual, and error-prone process. A collaborative environment that is built on abstract model and performance template allows engineering data and CAD/CAE results to be shared across above discipline boundaries within a common interface, so that it can help to attain speedy multivariate design and directly evaluate optical performance under environment loadings. A small interdisciplinary engineering team from Beijing Institute of Space Mechanics and Electricity has recently conducted a Structural/Thermal/Optical (STOP) analysis of a space camera with this collaborative environment. STOP analysis evaluates the changes in image quality that arise from the structural deformations when the thermal environment of the camera changes throughout its orbit. STOP analyses were conducted for four different test conditions applied during final thermal vacuum (TVAC) testing of the payload on the ground. The STOP Simulation Process begins with importing an integrated CAD model of the camera geometry into the collaborative environment, within which 1. Independent thermal and structural meshes are generated. 2. The thermal mesh and relevant engineering data for material properties and thermal boundary conditions are then used to compute temperature distributions at nodal points in both the thermal and structures mesh through Thermal Desktop, a COTS thermal design and analysis code. 3. Thermally induced structural deformations of the camera are then evaluated in Nastran, an industry standard code for structural design and analysis. 4. Thermal and structural results are next imported into SigFit, another COTS tool that computes deformation and best fit rigid body displacements for the optical surfaces. 5. SigFit creates a modified optical prescription that is imported into CODE V for evaluation of optical performance impacts. The integrated STOP analysis was validated using TVAC test data. For the four different TVAC tests, the relative errors between simulation and test data of measuring points temperatures were almost around 5%, while in some test conditions, they were even much lower to 1%. As to image quality MTF, relative error between simulation and test was 8.3% in the worst condition, others were all below 5%. Through the validation, it has been approved that the collaborative design and simulation environment can achieved the integrated STOP analysis of Space Camera efficiently. And further, the collaborative environment allows an interdisciplinary analysis that formerly might take several months to perform to be completed in two or three weeks, which is very adaptive to scheme demonstration of projects in earlier stages.

Product design tends to be more complex and needs the effective cooperation among multidisciplinary designers and engineers. An ideal product design environment, which is both collaborative and intelligent, will be much appreciated. Agent technology is an innovative and promising approach to implementing distributed systems and is becoming popular in various areas of computing in recent years. In this paper, the dynamic nature of collaborative design process and the representation of collaborative design knowledge are presented. In order to model constantly evolving design process and the rationales resulted from collaboration, a Collaborative Product Data Model (CPDM), which extends traditional Product Data Model (PDM), and a constraint-based Collaborative Design Process Model (CDPM) are proposed. These are intended to facilitate the management and coordination of collaborative product design process and knowledge management. A design example is used to illustrate CDPM. While the system is being implemented, the architecture of our agent-based collaborative product design environment based on CPDM and CDPM is described.

The second axis of the Dual Axis Radiographic Hydro-Test (DARHT) facility utilizes a long pulse electron beam having a duration in excess of two microseconds. This time scale poses problems for many conventional diagnostics that rely upon electrical cables to transmit signals between the accelerator and recording equipment. Recognizing that transit time isolation is not readily achieved for the long pulse regime, difficulties resulting from ground loops are anticipated. An electro-optic (EO) voltage sensor technology has been developed to address this issue. The EO sensor exploits the Pockels effect in Bi{sub 4}Ge{sub 3}O{sub 12} (BGO) to provide linear modulation of laser light in response to the voltage induced on a pickup electrode. Fiber coupling between the light source, Pockels cell and receiver ensures complete galvanic isolation with improved cost and performance as compared to conventional sensors fitted with fiber optic links. Furthermore, the EO approach requires that only the passive sensor element be located near the accelerator while the light source and receiver can be installed in remote locations. This paper describes the design and development of EO sensors for electron beam and pulsed power monitoring on the second axis of DARHT. Typical calibration and testing data for the sensors is also presented.

Personal assistant agents for collaborative design environments

Pulsed power and intense electric field now apply to a large variety of domains for which the need of in situ nonperturbative measurements remains a challenge. The main requirements that sensors should fulfill for that purpose are nonmetallic composition, small size, ultrawide bandwidth, compatibility with liquids and gases, possibility for remote measurements at long distances, true vectorial (field direction) time-domain measurements, capability of measuring electric fields up to the electric breakdown of air, and a large dynamic range. Obviously, all these requirements cannot be achieved by a unique sensor. However, most of them are fulfilled by pigtailed electrooptic (EO) sensors. In this paper, after recalling the principle of the EO effect and its use for electric field measurement, we deal with the measurement linearity and selectivity of the EO sensor. Associated with the nonperturbative behavior of the EO sensor, the measurement dynamics of EO sensors exceeds 100 dB. Furthermore, EO sensors present an intrinsic flat response from quasi d.c. (10 Hz) up to a few tens of gigahertz. Thanks to their composition of high dielectric strength materials and their optical pigtail, EO sensors are completely immune to the electromagnetic environment except on a very small volume (≅ 10 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) corresponding to the transducer element of the sensor. This leads to a very high spatial resolution. We finally illustrate the capabilities of this technology through in situ measurement of the electric discharge transients and vectors.

This paper reviews work on distributed collaborative virtual design environments and the emerging technology of metacomputing. The paper discusses the design of distributed collaborative design environments using metacomputing, for example Globus, to provide intensive data computing via an asynchronous collection of loosely synchronous components. The essential component, Globus, focuses on defining a toolkit of low-level services for security, communication, resource location, resource allocation, process management, and data access. Based on this approach, the requirements for concept, functionality and performance of the design environments are provided. The key functions in the distributed collaborative design environments such as analysis, visualisation, security and database management, particularly the 3D design storage and visualisation, are also discussed. Finally, further work on implementing Globus-based distributed collaborative design environments is highlighted.

In distributed collaborative design environments, product models and virtual studios should keep consistency to create sense of sharing the world and collaboration among physically distributed users. Model consistency is usually achieved by maintaining dynamic shared states. To make those events in physical locations virtually "seen" by the other participants, networks communications are indispensable. Because of limited network bandwidths and CPU resources in distributed and collaborative design environments, to decrease communication traffic is a critical issue. In this paper, we present a "near-sight" mode, which resorts to a method of using AOI, area of interest, to reduce efficiently communications to maintain dynamic shared states.

In this study, photonics-based near-field measurement and far-field characterization in a 300-GHz band are demonstrated using an electrooptic (EO) sensor with planar scanning. The field to be measured is up-converted to the optical domain (1550 nm) at the EO sensor and delivered to the measurement system with optical fiber. The typical phase drift of the system is 0.46° for the one-dimensional measurement time of 13 s, which is smaller than the standard deviation of the phase measurement of 1.2° for this time scale. The far-field patterns of a horn antenna calculated from the measured near-field distribution are compared with that measured with the direct far-field measurement system using a vector network analyzer. For the angular related parameters, the accuracy of the results obtained by our near-field measurement are comparable to that of those obtained by direct far-field measurements. The sidelobe level discrepancy (approximately 1 dB) between the results obtained based on our near-field measurement and those from the direct far-field measurements are attributed to the excess noise of the probe correction data. We believe that photonics-based near-field measurements with spherical EO probe scanning will pave the way for the characterization of high-gain antennas at the 300-GHz band.

This paper discusses the results of experiments on using an electro-optical (EO) sensor to detect an aerial intruder based on a small unmanned aerial system (sUAS) and assess its intentions. When matured, this technology can be used for enabling vision-based situational awareness and mid-air collision avoidance when operating in a cluttered environment, as well as for counter-UAS operations. The paper starts with a discussion of a theoretical capability of vision-based sUAS detection using an EO sensor onboard a drone, followed the outline of a simple drone detection algorithm. It then proceeds with reviewing a series of field experiments conducted to assess the algorithm's operational effectiveness. The tests results demonstrate the viability of the proposed approach, thus suggesting further exploration.

Refurbishment of building services engineering systems under a collaborative design environment

Collaborative virtual environment for product design occurs between people and often involves 3D objects. Fruitful cooperation is helped by natural and intuitive way of communication and interaction, for which responsiveness and consistency are leading factors. In order to guarantee consistency and improve responsiveness, a novel concurrency control scheme is first proposed. In our scheme, non-exclusive concurrent manipulations are merged so as to undo a small quantity of manipulations rather than all the operations triggered by users who are not granted, therefore, a majority of concurrent operations are collision-free and executed immediately to maximize responsiveness. Moreover, notification and visual indicator mechanism are used to avoid unnecessary concurrency collision. The implementation of collaborative virtual environment named VRCAD is then introduced in detail, including system architecture, concurrency control strategy and communication facilities. Experiment and practice show that our concurrency control scheme is effective and efficient for collaborative virtual environment involving 3D objects.

Surveillance sensors are being applied in factory automation systems, traffic control, entrapment protection, automotive safety systems and in other applications where information about the occupancy of a scene is required. In order to detect object motion several methods exploiting distinct physical phenomena, e.g. passive infrared sensors or active microwave sensors, have been realized. When comparing all of the applicable methods, the electro-optical approach performs very well with respect to the spatial resolution of the monitored area. Therefore, electro-optical sensors are able to provide additional information, e.g. to predict the direction of motion, or to localize and identify objects. However, convenient image processing systems using CCD sensors for image acquisition and DSP or /spl mu/P boards for signal processing and classification are not well suited for dedicated, powerful and cost-effective optical sensor solutions. In contrast to this mainstream approach CMOS based imaging technologies offer novel solutions in both the design and applications of electro-optical surveillance sensors. This contribution discusses CMOS imager operating principles and describes certain architectures and applications for passive and active surveillance sensors. The capabilities for realizing on-chip motion detection and range sensing using fast shutter devices are illustrated. We conclude with a discussion of the status of CMOS surveillance sensors and suggest trends for future applications.

This paper puts forward a multi-agent integrated platform. By studying the internal structures, ways of action and communication, functions, process algorithm, implementation patterns of different types of agents, and the specific method to realize autonomous and cooperative agent, it puts forward a mode of establishing enterprise's collaborative design environment. This mode takes the agents as distributed group decision making units; offers the enterprise information integration platform with clear structure, and makes it more open, integrated, and adaptive

This paper presents the development of Robot Technology Components (RTCs) using RT-Middleware (RTM) for designing assistive robotic arms and human-machine interfaces (HMIs) that can be used by the disabled. RTM is an open software platform for a component-oriented robot system. An RTC is the basic functional unit for constructing a robot system using RTM. The interface definition for the basic functionality of RTCs is standardized by the Object Management Group (OMG). Therefore, software modules written as RTCs can be shared and reused in other robot systems. One feature of an assistive robotic arm is that the arm is controlled by manual operation. Various HMIs for manually operating the robotic arms have been developed according to the abilities of each user and the requirements regarding the actions that the robot can perform. These HMIs can be interchangeably connected to the assistive robotic arms by implementing the software modules for the robotic arm and the HMI as RTCs with a common software interface.

Modern high performance computer systems continue to increase in size and complexity. Tools to measure application performance in these increasingly complex environments must also increase the richness of their measurements to provide insights into the increasingly intricate ways in which software and hardware interact. PAPI (the Performance API) has provided consistent platform and operating system independent access to CPU hardware performance counters for nearly a decade. Recent trends toward massively parallel multi-core systems with often heterogeneous architectures present new challenges for the measurement of hardware performance information, which is now available not only on the CPU core itself, but scattered across the chip and system. We discuss the evolution of PAPI into Component PAPI, or PAPI-C, in which multiple sources of performance data can be measured simultaneously via a common software interface. Several examples of components and component data measurements are discussed. We explore the challenges to hardware performance measurement in existing multi-core architectures. We conclude with an exploration of future directions for the PAPI interface.