Saturday, July 30, 2016

Origami design process

In their article in the Journal of Mechanical Design, Jessica Morgan, Spencer P. Magleby and Larry L. Howell presented a design process for mechanisms that use origami (folding).

Their design process can be viewed as a separation in which there is a set of logically related decisions that must be made (subproblems that must be solved):

  1. Decide to use origami solution.
  2. Select the general material behavior options (hybrid, rigid, multiple, flexible).
  3. Select a seed origami (fold pattern).
  4. Choose modifications to the fold pattern, including the actuation method, the thickness, the hinge, and the manufacturing method.
  5. Select the precise material.

Their paper lists some aerospace applications, including bellows to protect drill shafts on interplanetary rovers, an expandable habitat for the International Space Station, and
a parabolic antenna.

Reference:
Morgan J, Magleby SP, Howell LL. An Approach to Designing Origami-Adapted Aerospace Mechanisms. ASME. J. Mech. Des. 2016;138(5):052301-052301-10. doi:10.1115/1.4032973. 
http://mechanicaldesign.asmedigitalcollection.asme.org/article.aspx?articleid=2513965&resultClick=1
 

Thursday, July 28, 2016

Estimating Cost and Time at NASA

The U.S. Government Accountability Office investigated NASA's program to build the Space Launch System and the Orion spacecraft and released a report that recommends changes to how NASA assesses the cost and schedule risk of these programs.

According the GAO, there are both technical challenges (such as the heat shield for the Orion spacecraft) and management challenges.  The two are related, of course, because "technical challenges could result in cost overruns and schedule delays."

For assessing the cost and schedule risk, NASA used a joint cost and schedule confidence level (JCL) analysis but followed few best practices for estimating cost and schedule.  In particular, "the Orion cost estimate met or substantially met 7 of 20 best practices and its schedule estimate met or substantially met 1 of 8 best practices."  The GAO concluded that "Without sound cost and schedule estimates, decision makers do not have a clear understanding of the cost and schedule risk" and recommended that NASA managers "perform an updated JCL analysis with cost and schedule estimates in line with best practices."

Links:
GAO report: http://www.gao.gov/products/GAO-16-620
Paper on JCL methodology: http://arc.aiaa.org/doi/abs/10.2514/6.2013-5524

Thursday, July 14, 2016

Search Strategy for Pokemon Go

How do you find the Pokemon in Pokemon Go?  Just for fun, I developed a search strategy that has three phases: Explore, Calculate, Search.  You can find a description in my report.  Please let me know if you have suggestions or know of related work.