Concept Evaluation Methodology for Extraterrestrial Habitats

The paper examines and compares structural concepts considered for use as habitats for lunar and Martian outposts. An evaluation methodology that allows numeric rating of concepts was previously developed and is upgraded herein. The methodology defines a number of important characteristics on which concepts are to be judged. In addition, weighting factors are assigned for the various characteristics considered in the evaluation system. These factors are presented as variables that depend on mission goals and timing aspects. An example evaluation is made for a specific scenario utilizing the developed methodology. The overall purpose of this work is not to provide an absolute rating, but rather to identify strengths and weaknesses of concepts. This approach should be invaluable in the development and selection of structural concepts for extraterrestrial habitats.     

Engineering Test Support for Construction in Space

A number of engineers and constructors have been looking at the engineering analyses and syntheses associated with preparations for the establishment of a base on the Moon and human flight to Mars. This paper discusses the importance of early involvement of the engineering test perspective and approach in the engineering analysis, design, and development of capabilities for this construction activity in space, especially construction that incorporates the use of extraterrestrial resources. The effectiveness and suitability of mission equipment and proposed resource extraction processes must be shown by analysis, simulation, ground test, and flight test. Facilities and resources for test and evaluation (T&E) of extraterrestrial facilities must be acquired in a timely fashion, and time must be allowed for T&E.     

Common Characteristics of Terrestrial and Space Construction

The building of stationary facilities in space and on the lunar surface will bring humankind to the verge of a new era in its exploration of space. Many new and unprecedented construction problems have to be solved. Terrestrial construction technology, developed over centuries, had to overcome similar earthbound extremes. Viable examples include underwater construction and building on the frozen terrain of north and south poles. Many specialized techniques and kinds of equipment have emerged to meet those extreme conditions. This body of knowledge and technology may become a valuable resource for the design and construction of buildings in space. The objective of this paper is to demonstrate why experts from space technology and construction engineering should combine their specialized knowledge to benefit human advances into space.     

Computational Methods for Coordinating Multiple Construction Cranes

The incremental coordination method a computational method for preplanning and coordinating the use of multiple tower cranes in relatively narrow construction sites is presented. The incremental coordination method considers the kinematics and the geometrical constraints of cranes to plan the motion of two or more cranes, which are being operated in collaboration. By following such planned motions, erection tasks are completed safely, even when the cranes are operated in close proximity of each other. This method allows the use of computers to plan and coordinate the crane activities from start to end of an erection process. This paper also explains the computational methods required by the incremental coordinate method including path-finding and collision detecting methods. An example case shows two construction cranes, each of three degrees-of-freedom, operating together on a building project where the working areas of the cranes intersect, hence possibility colliding with each other. A numerical test was conducted to verify the efficiency and effectiveness of applying the incremental coordination method in planning and synchronizing all motions of the two cranes to avoid any collision between the cranes themselves and collision with obstacles on the construction site.     

Graph‐Theory Approach to Eigenvalue Problem of Large Space Structures

The dynamic analysis and control system design of large space structures involve the solution of the large‐dimensional generalized matrix eigenvalue problem. The computational effort involved is proportional to the third power of the dimension of the matrices involved. To minimize the computational time a graph‐theory approach to reduce a matrix to lower‐ordered submatrices is proposed. The matrix‐reduction algorithm uses the Boolean matrices corresponding to the original numerical matrices and, thus, the computational effort to reduce the original matrix is nominal. The computational savings directly depend upon the number of submatrices into which the original matrix is reduced. A free‐free square plate is considered as an example to illustrate the technique. In this example a matrix of 16th order is reduced to three scalars corresponding to three rigid‐body modes, and three matrices of order three and one matrix of order four.     

Concepts for Lunar Outpost Development

This paper summarizes the results of a qualitative investigation to identify concepts for design and construction of near‐term lunar facilities. Accomplishing such construction will require an adaptation or transfer of current terrestrial technology and methods. Discussions on modularization, geosynthetic materials, aluminum materials, static load analysis, and dynamic load analysis provide illustrative examples of how terrestrial technologies can be adapted to lunar applications. These discussions provide support for the development of a phased lunar construction strategy. The initial stage of construction is characterized by small self‐supporting accomodation and laboratory modules. The assembly facility stage is characterized by the construction of a large pressurized module‐assembly facility. The module production stage is characterized by the fitting together of terrestrial or low earth‐orbit subassemblies into completed modules within the module assembly facility. The completed modules are also tested and moved to their final location in this stage. The lunar materials stage is characterized by the construction of facilities with maximum use of lunar materials.     

Distributed Augmented Reality for Visualizing Collaborative Construction Tasks

Augmented reality is a visualization method in which virtual objects are aligned with the real world and the viewer can interact with the virtual objects in real time. In this paper, a new methodology called distributed augmented reality for visualizing collaborative construction tasks (DARCC) is proposed. Using this methodology, virtual models of construction equipment can be operated and viewed by several operators to interactively simulate construction activities on the construction site in augmented reality mode. The paper investigates the design issues of DARCC including tracking and registration, object modeling, engineering constraints, and interaction and communication methods. The DARCC methodology is implemented in a prototype system and tested in a case study about a bridge deck rehabilitation project.     

Dynamic 3D Visualization of Articulated Construction Equipment

Dynamic three-dimensional (3D) animation can be of significant value in improving the verification validation, and communication of discrete-event simulation (DES) models of construction operations, which in turn can make the models more credible and thus useful in operations planning and decision making. This paper presents research that led to the design and implementation of practical 3D animation methods to visualize multiply-articulated construction equipment in 3D animations of simulated construction operations. Using principles of forward and inverse kinematics, the writers designed and implemented generic virtual pieces of articulated construction equipment that accept task-level instructions from external software processes. DES models can configure and instantiate specific pieces of such equipment and instruct them to perform construction tasks using simple parametric text statements that embody a construction work-like terminology. Once instructed to perform specific tasks (e.g., load soil), these “smart” pieces of equipment (e.g., backhoes) automatically decipher the sequence and amplitudes of the elemental motions their components (e.g., boom, stick) must undergo to accomplish those tasks. The animation methods are implemented in a software tool called KineMach that integrates as an add-on with the VITASCOPE visualization system.     

Accumulative Sliding Construction Method for Large-Span Latticed Shells

This note proposes an efficient and cost-effective construction method for longitudinally supported large span latticed shell structures, commonly used for storages of existing stockpiles such as coal, stones, etc. The method divides a latticed shell into several segments, each of them is constructed sequentially. First, one segment-width scaffold is built at the assembling end of the structure. Then one segment of the structure is assembled on the scaffold. Once completed, the segmented structure is slid toward the other end of the structure to allow the scaffold to be available for assembling another segment. By repeating the above procedure, the entire segmented structure will form the resulting lattice shells. In the note, this construction method applied to two long span shell structures is discussed in detail. Structural analyses for each of the two accumulative sliding constructions have been examined before the construction, together with some suggestions for future similar applications using the method. From this note, researchers may transform the mobile construction method to explore other construction methods and practitioners of this technology can apply this method more safely and properly.     

Total Quality Management for Construction

Traditional approaches to quality control in the construction industry are inadequate and should be replaced with the Total Quality Control concept implemented through the Quality Control (Q.C.) Circle as developed in Japan and currently in wide use throughout the manufacturing industry. The term “total quality control” is defined, and four total quality control principles are set forth on the basis of this definition. The evolution of quality control is traced from the nineteenth century to today to explain the decline in quality standards and to illustrate the need for a new approach. Unique characteristics of the construction industry are described as they relate to the Q.C. circle concept. Implementation of this concept will result in higher quality, lower costs, and increased productivity in the construction industry.     

Four-Dimensional Visualization of Construction Scheduling and Site Utilization

Four-dimensional (4D) models link three-dimensional geometrical models with construction schedule data. The visual link between the schedule and construction site conditions is capable of facilitating decision making during both the planning and construction stages. The emphases of these 4D developments have often been placed at the level of construction components. Practical features assisting site management are at times lacking in the following areas: (1) generation of site usage layouts; (2) estimation of quantities of construction materials; and (3) cost evaluation. In order to pinpoint these deficiencies, the objective of this work is to enable visual study of the effects of job progress on the logistics and resource schedules. This paper presents a 4D visualization model that is intended both to help construction managers plan day-to-day activities more efficiently in a broader and more practical site management context and to thereby add to our knowledge and understanding of the relevance of modern computer graphics to the responsibilities of the construction site manager. A brief site trial of the software is described at the conclusion of the paper.     

Iconic Animation for Activity-based Construction Simulation

This paper discusses the development of an animation tool for the activity-based construction (ABC) modeling and simulation system. The tool uses an activity-based network diagram, i.e., ABC simulation model, as the animation background image, and uses precreated two-dimensional (2D) iconic images for simulation entities (e.g., resources). The animation process displays the queuing status and dynamic movements of 2D iconic images on the background. It also distinguishes active and idle states of resources and activities. Dynamic reports are available for selected activities with graphs including the production rate and utilization of involved resources. From visualizing the change of status of a simulation process and dynamic interaction between simulation entities in the process, the user can better understand the dynamic nature of the construction process. Animation provides an avenue to demonstrate how dynamic operations are simulated. It also provides an effective tool for the user to verify a simulation model and to validate the obtained simulation results. Compared to other systems, the ABC animation does not require any extra effort in addition to the ABC simulation model constructed for simulation purposes. Therefore, the presented technology greatly reduces the time and cost for achieving animation. A variety of useful information can be observed through animation, and is illustrated using two construction examples.     

Mechanical Equipment Requirements for Inflatable Lunar Structures

Inflatable structures have been proposed by a number of authors. Several structural forms have been conceptually designed, including spherical, pillow‐shaped, semicylindrical, and domed saucer. Regardless of structural form, all inflatables require mechanical equipment to initiate and maintain inflation. This paper identifies the mechanical equipment and operations required to support an inflatable structure. A previously proposed semicylindrical structure is selected for this study, but the principal results are applicable to all inflatable structures. The results indicate that air for inflatable structures should be transported to the moon in a liquid (cryogenic) state. The liquefied air can be evaporated and heated to the proper temperature using solar energy and a conventional pumping system. Removing the air from the facility is an entirely different problem and requires different equipment. There are two alternatives: (1) Discharge the air to the moon; and (2) reclaim the air for reuse. The first alternative is not likely to be cost‐effective and might well be scientifically unacceptable. The second alternative presents numerous technical problems but appears technically feasible.     

Design and Construction Considerations for Lunar Outpost

Engineers utilize various codes in the process of design, whether structural, mechanical, or otherwise. Reliance on a code for design is based on the knowledge that a tremendous amount of time and effort was spent by experienced engineers to codify theories and good practice in a particular design discipline. Good practice in structural design implies cognizance of materials, structural behavior, environmental loadings, assumptions made in analysis and behavior, and the uncertainties inherent in all of these. The American Institute of Steel Construction's (AISC) Manual of Steel Construction is such a codification for the design and construction of steel structures. It includes information, some tabular and the rest in the form of specifications and commentaries, necessary to design and provide for the safe erection of steel‐framed structures. The design equations are generally semiempirical, that is, they are based on a mix of theoretical analysis, experimental data, and factors of safety. Each of these components has associated implicit assumptions. Some of these assumptions were explored to understand how and if the Earth‐based design code could be used for the design of a lunar outpost. Topics discussed come from the AISC Code of Standard Practice and the commentaries, and issues such as scaling of loads and strength in the 1∕6 g lunar environment, thermal cycling effects and fatigue, stiffening and buckling are briefly discussed. Important topics for further detailed study include: (1) The relationships between severe lunar temperature cycles and fatigue; (2) very low temperature effects and the possibility of brittle fractures; (3) outgassing for exposed steels and other effects of high vacuum on steel∕alloys; (4) factors of safety originally developed to account for uncertainties in the Earth design∕construction process undoubtedly need adjustment for the lunar environment; (5) dead loads∕live loads under lunar gravity; (6) buckling∕stiffening and bracing requirements for lunar structures that will be internally pressurized; and (7) consideration of new failure modes such as high‐velocity micrometeorite impacts.     

Georeferenced Registration of Construction Graphics in Mobile Outdoor Augmented Reality

This paper describes research that investigated the application of the global positioning system and 3 degree-of-freedom (3-DOF) angular tracking to address the registration problem during interactive visualization of construction graphics in outdoor augmented reality (AR) environments. The global position and the three-dimensional (3D) orientation of a user’s viewpoint are tracked, and this information is reconciled with the known global position and orientation of superimposed computer-aided design (CAD) objects. Based on this computation, the relative translation and axial rotations between the user’s viewpoint and the CAD objects are continually calculated. The relative geometric transformations are then applied to the CAD objects inside a virtual viewing frustum that is coincided with the real world space that is in the user’s view. The result is an augmented outdoor environment where superimposed graphical objects stay fixed to their real world locations as the user navigates. The algorithms are implemented in a software tool called UM-AR-GPS-ROVER that is capable of interactively placing static and dynamic 3D models at any location in outdoor augmented space. The concept and prototype are demonstrated with an example in which scheduled construction activities for the erection of a structural steel frame are graphically simulated in outdoor AR.     

Hedratecture and Expandable Platform

This paper is directed only to the basic aspects of hedratecture. The word hedratecture is derived from the Greek “to build with hedrons.” It is used to describe the art and science of constructing with framed elements that are hedron‐shaped, usually in the form of the five convex polyhedrons. Hedratecture encompasses two major elements: the expandable platform and structures thereon. The platform when set on a surface by computer has the capability to incorporate within itself a whole variety of integrated lesser structures that provide dwelling units and a modular internal transportation system. The platform can be placed in a designated area as a hedron city or expanded in a linear dimension and in that mode it becomes a trestle or a bridge. The basic elements provide an endless variety of shapes with uses that vary from a small helicopter pad to a small city on earth. When placed on the Moon or Mars it can provide a telerobotically placed base.     

Construction of Pressurized, Self‐Supporting Membrane Structure on Moon

This paper draws attention to the importance of readiness time (i.e., the time it takes to develop the necessary supporting infrastructure on the Moon for the structure to be ready for use) of a lunar structure. It illustrates a rational process of determining readiness time using for an example the pressurized self‐supporting membrane structure (PSSMS), a concept proposed in 1989. To assess manpower requirement for construction, it is necessary to assess the productivity of a construction crew on the Moon, taking into consideration the hazardous conditions they confront, and the encumbrances due to the use of space suits and other protective systems. These handicaps can be compensated to some extent by making maximum use of mechanical and automatic equipment. The procedure adopted here is to determine the manpower requirement for a similar construction on Earth, then adjust it to the conditions on the Moon. Once the productivity factor relative to Earth is determined, the manpower requirement for lunar construction can be assessed.     

Design and Construction of Shielded Lunar Outpost

The construction of an outpost on the Moon in which humans can live and work for periods exceeding six months will require special countermeasures to adapt to the hostile environment present at the lunar surface. Various inherent dangers such as meteoroids, galactic cosmic radiation, solar proton events, and large thermal extremes will drive the design configuration of the outpost. Other considerations such as lunar soil mechanics, equipment performance, mass delivery, risk, reliability, and tele‐operability act strongly as constraints that shape and control the design alternatives. Analysis of these fundamental relationships have resulted in lunar civil engineering guidelines, which are unique to this domain, and these in turn have pointed to research areas needing further attention. A preliminary design is presented for a lunar outpost shelter. Additionally, the design methodology is explored, and early enabling technologies are identified to facilitate an understanding of lunar shelter designs from an integrated system standpoint.     

Automated Generation of Operations Level Construction Animations in Outdoor Augmented Reality

Three-dimensional (3D) visualization is an effective tool for communicating, verifying, and validating the results of a simulated operation. Traditional visualization tools used for this purpose are typically based on the paradigm of virtual reality. Augmented reality (AR) is a relatively newer visualization paradigm whose engineering applications have been explored by a limited number of researchers. In this paper, the problem of generating smooth and continuous AR animations from the results of running discrete event simulation models and a general purpose methodology to overcome this challenge are discussed. The structure of an AR animation authoring language developed by the writers to create a logical link between a running simulation model and its corresponding 3D visualization in AR is described. In order to validate the functionality and effectiveness of the designed methods and animation language, an AR-based visualization application was developed and the designed algorithms were successfully tested using different simulation scenarios of varying visual and operational complexity.     

Potential Mechanisms for Construction Innovation

Construction presents important opportunities for innovation. Current competitive conditions and owner demands for cost effectiveness provide strong incentives. Examining mechanisms for innovation rather than barriers to technical progress is one means to stimulate advance. This paper describes several advantages and disadvantages which the construction industry presents for innovation. The advantages include project organization, necessity and challenge, engineering and construction integration, low capital investment, capability and experience of key personnel, process emphasis, and variation in methods. Major disadvantages for construction include investment reluctance, competitive conditions, institutional framework, seasonal and economic cyclicity, and the role of suppliers. Based on these conditions, a set of hypotheses is developed (project demands, individual initiative, construction input to design, and transfer from other industries) concerning possible mechanisms for innovation in construction. The paper also reviews prior research regarding innovation in construction and manufacturing, develops practical applications of mechanisms for construction innovation, and highlights conclusions regarding opportunities for technological progress in construction.