Space systems. Design guidelines for multi-geo spacecraft collocation

2021 ◽  
Keyword(s):  
Systems Design ◽  
Design Guidelines ◽  
Space Systems

Toward a User-Centered Method for Studying CVEs for Learning

2005 ◽  
pp. 269-301 ◽  
Author(s):  
Daphne Economou ◽  
Steve Pettifer
Keyword(s):  
Interaction Analysis ◽  
Systems Design ◽  
Design Guidelines ◽  
Research Community ◽  
Collaborative Virtual Environments ◽  
Rigorous Approach ◽  
Third Phase ◽  
Virtual Actors ◽  
Design Factors ◽  
Grid Based

This chapter addresses one of the challenges the collaborative virtual environments (CVEs) research community faces which is the lack of a systematic approach to study social interaction in CVEs, determine requirements for CVE systems design, and inform the CVE systems design. It does this by presenting a method for studying multi-user systems in an educational context. The method has been developed as part of the Senet project, which is investigating the use of virtual actors in CVEs for learning. Groupware prototypes are studied in order to identify requirements and design factors for CVEs. The method adopts a rigorous approach for organizing experimental settings, collecting and analysing data, and informing CVE systems design. The analysis part of the method shares many of the Interaction Analysis foci and expands on it by providing a grid-based method of transforming rich qualitative data in a quantitative form. The outcome of this analysis is used for the derivation of design guidelines that can inform the construction of CVEs for learning. The method is described by a third phase of work in the Senet project.

The Effect of Scale on Fluid-Filled Flexible Composite Actuators

2011 ◽  
Author(s):  
Larry D. Peel ◽  
Luis Muratalla ◽  
Jeff Baur ◽  
Dean Foster
Keyword(s):  
Incompressible Fluid ◽  
Mechanical Energy ◽  
Systems Design ◽  
Critical Length ◽  
Variable Stiffness ◽  
Micro Air Vehicles ◽  
Design Guidelines ◽  
Segment Length ◽  
Actuation Force ◽  
Opening And Closing

Morphing aircraft and other shape-changing structures are well suited to McKibben-like flexible composite actuators. These actuators, made from fiber-reinforced elastomeric composites, are extremely efficient in converting potential energy (pressurized air) into mechanical energy. Such actuators are promising for use in micro air vehicles, prosthetics and robotics because they offer excellent force-to-weight ratios and behave similar to biological muscle. Use of an incompressible pressurizing fluid instead of compressible air may also offer higher actuator stiffness, better control, and compatibility with existing actuation systems. Using incompressible fluids also allows the actuator to serve as a variable stiffness element which can be modulated by opening and closing valves that constrain or allow fluid flow. The effect of an incompressible fluid (water) on the performance of Rubber Muscle Actuators (RMA), with varying diameters, lengths and segment lengths, was experimentally investigated in the current work. Upon pressurization with air or water, past an activation threshold, overall force and stroke increased with increasing actuation length and diameter. Actuation force when pressurized with water is slightly greater than with air. Both air and water-pressurized actuation force and strain decrease significantly when segment length is less than a minimum critical length. Closed valve actuator stiffness (modulus) of actuators at full length, when pressurized with an incompressible fluid is up to 60× greater than the open valve stiffness of the same actuator. Air-filled RMAs with equal parameters only see a 10× increase. Incompressible fluid-filled RMAs have great potential to provide needed high actuation forces within adaptive material systems. Design guidelines are given to aid additional RMA use.

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