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
 

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

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.

Book Award

At the IIE Annual Conference in Anaheim last month, Engineering Decision Making and Risk Management received the 2016 IIE/Joint Publishers Book of the Year Award.  I'd like to thank Gino Lim, who nominated the book, and those who supported this nomination.

The Wright Brothers

I just finished reading The Wright Brothers, by David McCullough.  It is a great story about two determined Americans who, like many engineers before and after, did their research and then designed, built, tested, improved, demonstrated, and marketed a remarkable invention.
The book describes not only their development process but also their personalities and family and friends, and I highly recommend it, but this is not a book review.

Flying is a risky endeavor, and Orville and Wilbur Wright made some key decisions to reduce personal and financial risk.  They decided to conduct their early glider and airplane tests at Kitty Hawk, North Carolina, which had not only good wind conditions for flying but also soft sand for landing.  They also decided to never fly together to avoid the risk that a crash would kill them both (only once, after many successful flights, did they fly together near their home in Dayton, Ohio).  They decided to keep their bicycle shop open to generate the profits needed to pay for the cost of their machines and the travel to North Carolina (they did not gamble their life savings on a speculative venture). 

On the other hand, they did accept some risk: they were not sure that their experiments would succeed, and every flight brought the potential for a crash.  Still, they learned from their failures, and managed the associated risks successfully.  Their story has important lessons about effectively managing risks.

UAV Operations and Failures

Earlier this month, the FAA's Micro Unmanned Aircraft Systems Aviation Rulemaking Committee (ARC) issued its recommendations in a final report: http://www.faa.gov/uas/publications/media/Micro-UAS-ARC-FINAL-Report.pdf

The recommendations include classifying UAVs (drones) into four categories, based on the risk that they pose to people underneath them.  If the UAV fails, it will crash and could cause a serious injury. 

If the mass of the UAV is less than or equal to 250 grams, then it would be in Category 1, which would have no additional restrictions (beyond those already in place).

UAVs more likely to cause a serious injury would face more restrictions.  For instance, Category 2 UAVs "must maintain minimum set-off distances of 20 feet above people’s heads, or 10 feet laterally away from people, and may not operate so close to people as to create an undue hazard to those people."  Category 3 UAVs would not be allowed to fly over crowds or dense concentrations of people.  A Category 4 UAV, on the other hand, could do that if it complied with a documented, risk mitigation plan.

There are many interesting details about the ARC, its risk attitude, how the ARC developed its recommendations, and other factors.  In particular, the ARC did not consider the likelihood of a UAV failure or the likelihood that it would hit someone if it failed; it considered only the distribution of the consequence (the chance of a serious injury) if it hit someone:  "Specifically, the ARC recommends that a small UAS be permitted to conduct limited operations over people ... if that UAS presents a 30% or lower chance of causing [a serious] injury upon impact with a person."

Fixing the Roof

Strong winds earlier this week in Maryland led us into two related but very different decisions.

I came home Monday afternoon to discover shingles lying next to the front door and hanging in the trees in the front yard of our house.  That was unusual, and I was further surprised to learn that they came from our roof!  The wind had lifted dozens from the roof on the back half of our house and blown them over the front. 

After viewing the damage from the ground and reading that the weather forecast included more high winds and thunderstorms this week, we hurried to find and hire someone to repair the roof quickly. 
Due to the extreme time pressure, this chaotic context (Snowden and Boone, 2007) forced us to find something that works and reestablish order (an adequate roof).  We quickly searched online resources, asked friends for references, and even opened the yellow pages (we still had one from 2010) to get a list of roofers, and we called around until we had a few lined up to call back or inspect it the next morning (that took seven phone calls).  Some of those who called back said that they didn't do repairs, so they were out.  The first roofer who actually showed up, looked at the roof, and gave us a price got the job.  It was a pure satisficing strategy - we picked the first adequate alternative.   (It was quick: one roofer called later that morning and was surprised that we had already selected someone.)  We had a fixed roof later that day, and we could sleep better that night.

That was the first decision.  We now face a second decision: to select someone to do a roof replacement (the current roof is over 20 years old, and the shingle incident this week is a precursor to more significant problems in the future).  This decision has a complicated context in which we have to get more information about the state of the roof from experts, reconcile their opinions, investigate the firms, make tradeoffs, and finally pick one. 

One roof, two decisions. Both have the same problem (pick the best roofer), but the contexts, relevant attributes, and decision-making processes are very different.

Reference cited: Snowden, David J., and Mary E. Boone, “A Leader's Framework for Decision Making,” Harvard Business Review, Vol. 85, Issue 11, pages 69-76, November 2007.