I find the Bode plot to be one of the most useful tools in all of Classical controls.  This is probably no surprise to anyone who works in the field.  Many of its uses are obvious.  However, I always wondered if there were a way to determine stability from the Bode plot.  After giving it some thought I assumed there was no way to determine if the pole had a positive or negative real part.  However, the Google group for controls has a topic on determining stability from the Bode plot.  Here’s the link.

My controls education…

During my time in Masters school I was given lots of simple models for which I was asked to design controllers. As an undergrad I was given several examples of systems to develop simple rigid body models for and then design a controller. All in all, when I graduated I found my education with regard to system modeling to be lacking.
My undergrad is in Mechanical Engineering and we did plenty of rigid body models of multiple degree of freedom systems. My Dynamics class was probably my best with regard to system modeling. However, this completely ignores the modeling of complex sensors and actuators.

An education in modeling

Modeling is largely a matter of judgement. Judgement based on experience but also based on performance. In LaserCom applications we are attempting to control line of sight (LOS) pointing to less than 10 micro-radian level with milli-radian (or larger) level disturbances at high frequencies. As a result we have to model not only 1st order effects but 2nd and 3rd order effects. If we were attempting to control the LOS to a milli-radian level or hundreds of micro-radians then 1st order effects would be adequate.

My controls education recommendation

My recommendation would be to scrap the typical undergrad controls course and turn it into a semester long project. The projects would start with an assessment of desired system performance. That performance becomes a way to derive requirements. The requirements become a means of determining whether the model needs to include 1st, 2nd or 3rd order effects. Actuators and sensors are modeled in successive stages of complexity. After the system, sensor, and actuator models are created then a full plant model can be formed – it will probably be at least 6th order.
The full plant model can then be approximated in order to design a controller. Then that controller can be tested against the approximate plant and the full plant. Root locus, pole placement, and PID controllers can be explored during this design phase.
Obviously the design of the controller will benefit from open loop, closed loop, and disturbance rejection bode plots. Stability can be assessed using the Routh stability criteria, Nyquist, Nichols, etc.

Once the controller performs well on the full plant quantization, saturation, etc can be explored.

At the end of the semester the students have the tools and they’ve used the tools.

SEO (Search Engine Optimization) is popular search topic on the web.  This is because your natural, or organic, search results – not the paid search ads – are based on your page rank (this is a Google term but something similar applies to the top 3 engines).  These organic results are the best and easiest way to drive traffic to your site.

Whether you are selling stuff, making money from your site through ads or donations, or just want people to read your blog you want traffic.  The more the better.  For years now the “gurus” have told new people to engage in link marketing.  In essence you, as the new site owner, goes to related blogs, forums, and wikis that established and you make meaningful contributions that include a link to your site.  After a while sites starting catching on that these links to other sites were lowering the page rank of the established site.  The result is that established sites started using the NO FOLLOW tag.  The link on an established site can still drive traffic to your site but it won’t improve your page rank so long as the NO FOLLOW tag is there.

Wikipedia started implementing a NO FOLLOW tag sometime back.  This was before I had a site or cared about SEO so I didn’t get too worked up about it.  However, a lot of people on the web made the argument that Wikipedia was the behemoth that it was because so many established sites included links to its articles – without the NO FOLLOW tag.

I started my wiki because I wasn’t happy with the content or organization of Wikipedia or the Wikibooks.  Neither site, in my opinion, was appropriate for advanced topics or examples.  I’ve made quite a few contributions to Wikipedia pages that I thought I could improve without wholesale re-write.  Now I’m having some of my edits backed out because of the external links to my site.  Admittedly these were edits solely to add links to related topics on my site.  However, my site includes exampels and MATLAB code not just the theory.

The Wikipedians argument is that I should just rewrite my content on Wikipedia.  I guess I’m selfish, I see no possibility of an upside for me and plenty of potential for a downside should I accidentally write something on Wikipedia I shouldn’t have – i.e. something my current or future employer doesn’t appreciate.

This reverting of edits by people who never bothered to judge my links in context and certainly are not subject matter experts has just pissed me off.  This on top of the NO FOLLOW tags and articles on the Edge makes me seriously question the utility of Wikipedia.  And the arrogance of many of the users.  Especially for subjects such as Engineering where you really do need subject matter experts and peer review.

I think my contributions to Wikipedia are over.  I will be making my contributions to places such as Knol.

I recently read a blog posting on CR4 that posed the question: “Science and technology change culture.  Are voters educated well enough in science and technology to assess who should be the US president come 2009?”

The replies to post immediately posed questions about God and religion.  I originally took this reply to be a joke.  But then every reply treated the original reply as serious and discussion worthy.  Besides being off topic, the reply annoys the hell out of me.

If you believe God gave you free will then you have a responsibility to educate yourself with respect to key issues.  If God did not give you free will then there is no harm in being educated on the key issues if only to help you understand God’s plan.  If you don’t believe in God then obviously you are responsible for your own actions and must be educated.

Technology is key to US national security.  Technology is key the US economy.  Bleading edge science in nanotech, genetcis, and computers are vital to growth of the US economy in coming decades.  Irresponsible use of nanotech could pose pollution style threats to our health.  How can we afford to be ignorant?

I’m an engineer and ideally I would, should I invent something, benefit from a patent.  However, the USA’s current patent system is showing a number weaknesses.

Patent Weakness #1: The patent office is filled with lawyers not scientists/engineers

The patent office has, for the past decade or so, been giving out patents for genes and software like Amazon’s One Click.

Pharma companies didn’t invent DNA or genes.  They simply discovered the gene for a disease and thereby a possible path to cure.  Why should anyone have to pay royalties for studying said gene or discovering a cure independent of the pharma that identified the gene.

In my opinion Amazon’s One Click patent was the epitomy of the stupidity of the patent office.  The patent clerks kept arguing for prior artwork deomonstrating that someone else had already developed a One Click feature.  This is ludicrous.  The point of software is automate mundane tasks with a minimal amount of information and work by the user.  So what does One Click do fundamentally different than any other button on any other piece of software?

Patent Weakness #2: Patents live way too long…

In an age where software and services change every 6 months on the internet, how does a 20 year patent fit into the equation?  It doesn’t, 20 years for a patent slows down our progress, it does not accelerate it.

The USA gets 1 cell phone version upgrade for every several that are seen in Asia.  Yet companies, like Sony, are still making plenty of cell phones.  Constantly reverse engineering those phones and producing the next cell phone generation.  Hmmm…  But, the whole world economy would just fall apart if we got rid of patents…

Patent Weakness #3: Companies stiffle innovation through intellectual property lawsuits in order to protect their market share

Currently many companies whine about an individual’s right to sue them because they feel abused by frivolous lawsuits.  However, this doesn’t stop big companies from suing little companies frivolously.  They sue over patent infringment.  Everyone in the courtroom knows the suit is frivolous but the big company ties up the little company in court for years.  Draining their resources, preventing the little companies from furthering their technology.  In the end the little guy goes out of biz or is so drained they are hardly competitive anymore.

Great use of the court system and my taxes go towards this crap.  Stiffling innovation is not only an economic issue but a national security issue.  As such, when companies stiffle innovation through the use of patents it hurts the entire country for years to come and when they stiffle innovation just to protect market share they deserve to be severely punished.  Not rewarded.

Time to wake up and heavily revise our patents and intellectual property…

Patents have served their purpose.  It’s time to get rid of them.

I’m watching the Olympics right now.  And at each medal ceremony we see nationalism.

Unsurprisingly I’m an engineer and I like Science Fiction.  I’ve read a number of Arthur C. Clarke’s latest books.  Along the way these stories suggest a number of dramatic changes for the human race driven by events like Climate Change.

More and more the internet is breaking down borders.  My question is, once Google or someone else develops a real time language translator with context, how long will nations last in any recognizable form?

I earned my Bachelors of Science in Mechanical Engineering in 1997.  My Master in Electrical Engineering in 2005.  While earning these degrees I attended 4 schools.  I have a couple of observations…

First Observation: Get Rid of Tests and Finals

Tests and finals are part of every level of education.  They don’t belong in Engineering education. 

The main thing a test grades is a student’s ability to accurately complete an arbitrary problem with very limited resources, no collaboration, and too little time to properly check your work.  Which of these skills is important after you leave school?

Some will argue that tests are the only way to assess a student’s individual ability.  I will admit that I don’t have an entirely adequate replacement.  In my mind that doesn’t justify all the downsides that come with testing.

There are few if any real world situations where your ability to solve an arbitrary problem in 15 minutes or less is important let alone critical.  In fact, the really good engineers that I know do their work thoroughly, double check it thoroughly, and for difficult design or analytical problems they seek out another engineer to double check their work or at least their assumptions.

Second Observation: Good designs are the result of collaboration

Few real world systems are designed by a single person.  Complex systems are tackled by large groups of people working in collaboration.  Student engineers need to learn how to work in teams.  More importantly student engineers need to learn how to quickly, succinctly, and clearly present complex questions and results in Word, PowerPoint, and MathCad documents.

Succinct presentations are a critical skill.  Succinct presentations help you, as an engineer, clarify your thoughts and boil down the issue to the key issue.  I can’t count the number of meetings I’ve sat through that should have been 15 minutes but an hour and a half later we’re still talking about some minor detail on the 3rd slide in the presentation.

More to follow…

USAF Space Plane Test Flight

Original Article

From what I’ve read this is only a technology risk reduction demonstration.  But I’d like to explore the possibilities behind a Space Plane.

It is unlikely that any Space Plane we build today would be capable of orbits much higher than the Shuttle’s or the International Space Station (ISS).  However, within that orbit it can still accomplish a lot.

Clean up Space Junk with a Space Plane

 All the satellites that have been put into orbit over the past 50+ years are beginning to create enough space junk that it is becoming a threat to anything and everything in orbit.  In Low Earth Orbit (LEO) there are pieces of previous satellites which pose a threat to the Shuttle and the ISS.  Even small pieces, pebbles really, moving at orbital speeds can destroy the spacecraft (unmanned and manned alike) that we build today.

Like the Shuttle a Space Plane could deliver payloads to LEO while providing a platform for manned control of the payload.  So a variety of space junk removal techniques could be attempted through manned control.  Ultimately, I think that space junk will have to be cleared via automated spacecraft but perfecting the techniques and tools will be greatly aided by having a person try several techniques while having a view that can only be afforded by being in close proximity.

Theatre specific resources from a Space Plane

 The Space Plane is not being built by NASA for civilian purposes it is being built by the US Air Force.  There are probably several reasons for this.  I’m not in the military and don’t have a lot of insight to this but I assume that at least one of the purposes is to bring resources to a specific combat or surveillance theatre.

We have lots of satellites in orbit but moving them (changing their orbit) is costly and dramatically reduces the life of the spacecraft.  A Space Plane may be capable of entering the appropriate orbit and providing intelligence gathering and sharing functions.

This is hard to gauge though.  It’s not as if the Shuttle can simply be launched at any moment and enter any orbit it likes.  The Space Plane would have significant limitations on its ability to enter the desired orbit.

A Space Plane is key to Space Power

In the 20th century military dominance came through air power.  In the 21st it will be space power.  That means the exploitation, commercially and militarily, of space it’s resources and ultimately it’s vantage point.  Space is the ultimate high ground right now.  Someone will put weapons in space – the advantages are just too great.

Obviously a Space Plane is a potential platform for weapons.  The US doesn’t have to put weapons on the Space Plane in order demonstrate that we can.  For now, that’s really the point.