Limited Workspace Research Articles

FM puzzle: sick building and Sydney’s open‐plan offices

Presents analytical findings of sick building situations in Sydney’s open‐plan offices. Aims to ascertain facilities managers’ perceptions of sick building impacts on discrete aspects of workspace management, with a view to raising general awareness. A total of 100 open‐plan offices in the Sydney CBD were studied, and collated data analysed using partial correlation. Significant associations were found between sick building syndrome and certain aspects. However, management control played moderating roles in some of the associations. Concludes that, with management control, sick building syndrome may be perceived as critical to only a limited workspace aspect. The implication is for sick building syndrome to be largely generalised as inconsequential to many aspects of work environment in Sydney, probably following the Hawthorne management ideology.

Testbed for Evaluating Tactical Situation Awareness and Decision Making

The next generation cruise missile, the Tactical Tomahawk, improves upon current versions by its ability to be retargeted in flight against targets of opportunity. We have developed a testbed for evaluating alternative display concepts and decision support features on the effect of an operator's ability to maintain situation awareness and make appropriate time-critical decisions. This user interface design was based on an analysis of critical operator tasks, and the concepts of representation aiding and limited workspace management. The testbed was developed with Macromedia Director, allowing it to be run cross-platform (Windows, Macintosh, and the Internet). One set of studies has been conducted so far with this system, to compare alternative display features on the effect of subject situation awareness and decision making.

An overview of the intuitive system: The surgeon's perspective

An overview of the intuitive system: The surgeon's perspective

Laparoscopic transabdominal suspension sutures.

A limited number of access ports used in laparoscopic surgery may impair the ability of the surgeon to achieve adequate retraction and exposure, or to stabilize "moving targets" while operating on nonfixed organs. Solutions such as adding more ports or using a hand-assisted technique have the disadvantages of being more invasive, possibly creating a cumbersome situation of multiple instruments in a limited working space. We describe a useful technique for retraction and stabilization with the use of temporary sutures that pass through the abdominal wall. Although not new, this technique is not widely known or used, and laparoscopic surgeons may find it useful for a variety of applications.

Combining speech recognition software with Digital Imaging and Communications in Medicine (DICOM) workstation software on a Microsoft Windows platform.

This presentation describes our experience in combining speech recognition software, clinical review software, and other software products on a single computer. Different processor speeds, random access memory (RAM), and computer costs were evaluated. We found that combining continuous speech recognition software with Digital Imaging and Communications in Medicine (DICOM) workstation software on the same platform is feasible and can lead to substantial savings of hardware cost. This combination optimizes use of limited workspace and can improve radiology workflow.

Computer-aided design and modeling of workstations and radiology reading rooms for the new millennium.

Three-dimensional (3D) computer modeling, simulation, and rendering techniques were used to redesign the diagnostic workstations and radiology reading rooms for a proposed hospital with particular attention given to lighting conditions, noise reduction, and optimal use of limited workspace. The results were presented to a panel of multidisciplinary experts and iteratively improved and redesigned with the development or addition of new design criteria or requirements. These 3D techniques allowed faster, more efficient design and presentation of multiple options than is possible with traditional two-dimensional drawings, thereby expediting decision making and resulting in significant savings. The current workstation designs can easily be developed and implemented with available technology at a reasonable cost. They can also accommodate anticipated advances in computer and display technology as well as new imaging paradigms (eg, changes in keyboard and control ergonomics such as adjustable virtual keys on touch-sensitive screens, digital drawing tablets for annotations and controls, direct film digitizing, personal identification devices, offline media readers such as compact disks and digital videodisks, and speech recognition and voice activation). Use of 3D techniques in designing other parts of the radiology department (eg, examination rooms, technologists' areas, physicians' offices) could greatly improve and facilitate the design and implementation of complex settings in these work areas.

Simultaneous versus sequential loading and scheduling of flexible assembly systems

A monolithic and a hierarchical approach is presented for loading and scheduling in a general flexible assembly system and a flexible assembly line. The system is made up of a set of assembly stations of various types each with limited working space and is capable of simultaneously producing a mix of product types. The objective is to determine an assignment of assembly tasks to stations and an assembly schedule for all products so as to complete the products in a minimum time. In the monolithic approach loading and scheduling decisions are made simultaneously. In the hierarchical approach, however, first the station workloads are balanced by solving the loading problem, and then detailed assembly schedule is determined for prefixed task assignments and assembly routes by solving a standard job-shop problem. Mixed integer programming formulations are presented for simultaneous and for sequential loading and scheduling. Loading and scheduling with alternative or with single task assignments are considered. Numerical examples are included to illustrate and compare the two approaches proposed.

Simultaneous Versus Sequential Balancing and Scheduling of a Flexible Assembly Line

Mixed integer programming formulations are presented for simultaneous or sequential balancing and scheduling of a flexible assembly line. The line is made up of a set of assembly stations in series, each with limited working space and is capable of simultaneously producing a mix of product types. The objective is to determine an assignment of assembly tasks to stations and an assembly schedule for all products so as to complete the products in a minimum time. Balancing and scheduling decisions can be made simultaneously or sequentially. In the latter approach first the station workloads are balanced, and then detailed assembly schedule is determined for prefixed task assignments and assembly routes by solving a standard job-shop problem. Balancing and scheduling with alternative or with single task assignments are considered. Numerical examples are provided and some computational results are reported to compare the two approaches.

Workspace Analysis of a Six-Degrees of Freedom, Three-Prismatic- Prismatic-Spheric-Revolute Parallel Manipulator

This paper studies the workspace of a six-degrees-of-freedom parallel manipulator of the general three-PPSR (prismaticprismatic-spheric-revolute) type. It is known that a drawback of parallel manipulators is their limited workspace. To develop parallel mechanisms with a larger workspace is of use to potential applications. The mechanism of a three-PPSR manipulator and its variations are briefly analysed. The workspace is then investigated and the effects of joint limit and limb interference on the workspace shape and size are numerically studied. The constituent regions of the workspace corresponding to different classes of manipulator poses are discussed. It is shown that the workspace of this parallel manipulator is larger than that of a comparable Stewart platform, especially in the vertical direction.

Microsurgical instruments for root-end cavity preparation following apicoectomy: a literature review.

Root-end cavities have traditionally been prepared by means of small round or inverted cone burs in a micro-handpiece. Since sonically or ultrasonically driven microsurgical retrotips became commercially available in the early 1990s, this new technique of retrograde root canal instrumentation has been established as an essential adjunct in periradicular surgery. At first glance, the most relevant clinical advantages are the enhanced access to root ends in limited working space and the smaller osteotomy required for surgical access because of the various angled designs and small size of the retrotips. However, a number of experimental studies comparing root-end preparations made with microsurgical tips to those made with burs have demonstrated other advantages of this new technique, such as deeper cavities that follow the original path of the root canal more closely. The more centered root-end preparation also lessens the risk of lateral perforation. In addition, the geometry of the retrotip design does not require a beveled root-end resection for surgical access thus decreasing the number of exposed dentinal tubules. A controversial issue of sonic or ultrasonic root-end preparation is the formation of cracks or microfractures, and its implication on healing success. The present paper reviews experimental and clinical studies about the use of microsurgical retrotips in periradicular surgery and discusses many issues raised in previous papers.

Intelligent Algorithm for Biped Robot for Harvesting Watermelons

Farm working usually involves a harsh environment such as limited work space and soft, unstable or uneven surfaces. High mobility even in such an environment is essential for automating agricultural tasks. Bipedal locomotion is an example of such mobility, but it is statically unstable. Biped robots for farm work must be controlled dynamically to maintain unstable equilibrium. No decisive control strategy for this problem had been mapped. Noting that biped locomotion is periodic and governed by a characteristic rhythm, we proposed control strategy based on locomotion rhythm. In an uncertain environment, the reference rhythm should be modified corresponding to its current state for realizing stable walking. We introduce the concept of ""compliance"" in our rhythm-based locomotion control to modify a priori defined reference rhythm so that the robot maintains its balance. Simulations and experiments demonstrate the feasibility of stable walking in an unfavorably environment.

On the inverse kinematics, statics, and fault tolerance of cable-suspended robots

This paper examines some issues concerning the inverse kinematics and statics of cable-suspended robots and studies some of the inherent workspace limitations that result from the fact that the robot is cable actuated. The paper presents necessary and sufficient conditions for a cable-suspended robot to stay in a given configuration (i.e., to achieve static equilibrium). Another important issue is the extent to which the cables constrain the robot. For example, fully constraining the robot is critical for space applications in which the robot must work in a zero-gravity environment. Conditions for completely constraining the robot are derived. The problems of achieving static equilibrium and fully constraining the robot are formulated in terms of the left null space of a manipulator inverse Jacobian. This null space formulation is also used to study the fault tolerance of cable-suspended robots that are redundantly actuated. © 1998 John Wiley & Sons, Inc.

Simulation in concreting operations: a comparison of models and resource combinations

Computer simulation in construction planning has been the subject of research for the last few decades. The present paper describes simulation models geared toward improving the productivity of concreting operations. It is primarily concerned with a study of the sensitivity of concreting operations to a set of possible resource combinations. Thirteen models are examined by the two well‐known methods of concreting: (1) crane and bucket; and (2) the pump. Concreting into slabs, beams and columns are considered. The simulation software Micro‐CYCLONE is used for the actual generation of models. Sensitivity parameters considered in resource combinations include the number of truck‐mixers, buckets and labourers in concrete placing crews. The simulation models developed are compared and the results are discussed. The results enable planners to realize how the resource quantities and capacities in one cycle affect the ones in another period for cyclic operations like concreting. It can be concluded that the maximum number of resources, the interaction of work crews caused by work space limitations and the interaction of equipment because of sharing with other activities of the project may bring limitations.

Performance statistics of a head-operated force-reflecting rehabilitation robot system.

Researchers in the rehabilitation engineering community have been designing and developing a variety of passive/active devices to help persons with limited upper extremity function to perform essential daily manipulations. Devices range from low-end tools such as head/mouth sticks to sophisticated robots using vision and speech input. While almost all of the high-end equipment developed to date relies on visual feedback alone to guide the user providing no tactile or proprioceptive cues, the "low-tech" head/mouth sticks deliver better "feel," because of the inherent force feedback through physical contact with the user's body. However, the disadvantage of a conventional head/mouth stick is that it can only function in a limited workspace and the performance is limited by the user's strength. It therefore seems reasonable to attempt to develop a system that exploits the advantages of the two approaches: the power and flexibility of robotic systems with the sensory feedback of a headstick. The system presented in this paper reflects the design philosophy stated above. This system contains a pair of master-slave robots with the master being operated by the user's head and the slave acting as a telestick. Described in this paper are the design, control strategies, implementation and performance evaluation of the head-controlled force-reflecting telestick system.

Singularity loci of planar parallel manipulators with revolute actuators

The determination of the singularity loci of planar parallel manipulators is addressed in this paper. The inverse kinematics of two kinds of planar parallel manipulators (a two-degree-of-freedom manipulator and a three-degree-of-freedom manipulator) are first computed and their velocity equations are then derived. At the same time, the branches of the manipulators are distinguished by the introduction of a branch index K i . Using the velocity equations, the singularity analysis of the manipulators is completed and expressions which represent the singularity of the manipulators are obtained. A polynomial form of the singularity loci is also derived. For the first type of singularity of parallel manipulators, the singularity locus is obtained by finding the workspace limits of the manipulators. For the second type of singularity, the loci are obtained through the solution of nonlinear algebraic equations obtained from the velocity analysis. Finally, the graphical representation of the complete singularity loci of the manipulators is illustrated with examples. The algorithm introduced in this paper allows the determination of the singularity loci of planar parallel manipulators with revolute actuators, which has been elusive to previous approaches.

Thoracoscopic transdiaphragmatic left adrenalectomy

The endoscopic approach to adrenal glands has been limited to laparoscopic and retroperitoneal access due to the relative inaccessibility of the retroperitoneal space in the former case and to the limited working space in the latter. We undertook this study to investigate the possibility of performing a left adrenalectomy through a thoracoscopic transdiaphragmatic approach in a swine model. Five pigs were anesthetized, intubated, and ventilated. Four laparoscopic trocars were inserted and a left pneumothorax was accomplished by CO2 insufflation. A peripheral posterior phrenotomy was made starting from the aortic hiatus and extended laterally for about 6 cm. The resulting pneumoretroperitoneum facilitated the subsequent identification of anatomic structures, allowing an easy exposure of the left adrenal gland. The gland was progressively dissected downward, interrupting the tributary vessels with endoscopic clips, and it was finally extracted through one of the trocar ports. Adrenalectomy was accomplished in all the animals without intraoperative mortality. Complications included splenic injury with prolonged bleeding and difficulty in performing the diaphragmatic suture (one case each). Through this approach direct and rapid exposure of the left adrenal gland was allowed, and adrenalectomy was accomplished in all the animals. These results suggest further investigations of the clinical application of this procedure.

An interactive approach to bicriterion loading of a flexible assembly system

This paper presents integer programming formulations and an interactive solution procedure for a bicriterion loading problem in a flexible assembly system. The system is made up of a set of assembly stations linked with an automated material handling system. In the system, several different product types can be assembled simultaneously. The problem objective is to assign assembly tasks and products to stations with limited working space, so as to balance the station workloads and to minimize station-to-station product transfer time, subject to precedence relations among the tasks for a mix of product types. The solution procedure proposed is based on the weighting method and the interactive search for a set of weights which would produce the most preferred nondominated solution. Numerical examples are included to illustrate possible applications of the interactive approach for various problem formulations proposed.

パラレルメカニズムを用いた上肢動作補助機構

Parallel mechanisms have advantages such as good force/torque output, high speed, and high accuracy. They can also manipulate the objects with soft links such as strings. Their limited workspace gives safety when the mechanism is used closely to human. Parallel mechanisms are suitable for robotic system for rehabilitation or assistance of the elderly people or the disabled people. Therefore, an upper limb motion assist system is proposed and being developed. This system aims at assisting people with upper limb disability to move the arm by his/her own will.Design strategy of the system is discussed at the first stage of the development, because it effects the motion range. In this paper, firstly a concept of the upper limb motion assist system is illustrated. Then, statics of the forearm motion with the proposed system is considered. An experiment is also carried out in order to determine a parameter included in statics. Finally, statics of the forearm and upper arm is considered and the relation between the design parameters of the system and the motion range of the arm is estimated using simulations.

SCaRC: Space-Constrained Resource-Constrained Scheduling System

Current intelligent scheduling systems do not address the effect of limited work space on the generation of schedules. This paper describes SCaRC—Space-Constrained and Resource-Constrained knowledge-based system—for scheduling repetitive floors in multistory projects. The prototype system incorporates space-based scheduling techniques to recognize the space requirements of activities as a scheduling constraint. The space-based techniques are integrated with resource-based techniques for the production of schedules. The system also incorporates procedures to define and verify construction logic constraints associated with linear scheduling of vertical construction. An example illustrating the scheduling techniques implemented in SCaRC is presented.

Determination of the orientation workspace of parallel manipulators

An important step during the design of a parallel manipulators is the determination of its workspace. For a 6-d.o.f. parallel manipulator workspace limitations are due to the bounded range of their linear actuators, mechanical limits on their passive joints and links interference. The computation of the workspace of a parallel manipulator is far more complex than for a serial link manipulator as its translation ability is dependent upon the orientation of the end-effector. We present in this paper an algorithm enabling to compute the possible rotation of the end-effector around a fixed point. This algorithm enables to take into account all the constraints limiting the workspace. Various examples are presented.