Brain Drain

For decades now the US has been the place for the best and brightest from other countries to study.  I sizable chunk decide to stay especially in engineering.  As a result when various companies and the US gov decided they needed more engineers they simply imported them.

God forbid we

1. actually pay and treat engineers like they are professionals
2. give them something to do other than shuffle paper work and dodge management

And yet some people still lamented the lack of native born engineers graduating from our schools.  Some were so blind as to wonder why so few were graduating.

Well it’s time to start paying the bill…

India’s Space Program

A large chunk of our imported engineers come from India.  Often they come here because opportunities are limited in India for people born to the wrong caste.  So the people that can get to the US come over, study engineering, and stay.  But it is harder and harder for them to get jobs in Aerospace since most of the Aerospace companies have chosen to pursue defense work.

Now India has started its own space program while the US program slowly decays.  A number of those Indian engineers that stayed here are asking if there are jobs in their home country working on the space program.

The economy in the US is tanking making jobs harder to come by.  The US space program and surrounding Aerospace industry is less welcoming than it used to be.  And many would like to go home if they can find good job opportunities.

Reverse Brain Drain

The emerging space programs of China and India are a serious threat to the US technological superiority.  It may be years before the programs show a string of years with real funding and enthusiasm at home.  However, once those programs are established a much larger percentage of those foreign born engineers that come here to study will go back home when they are finished.

We will have fewer engineers in the coming years.  Without something inspirational to bring native US kids back into engineering it will only get worse.  I’ve complained about the pay and nature of the business where companies lay off large numbers of people every time their sales hiccup for a quarter but that’s not really the problem.

We can’t keep expecting to drain the brains of India and China

The problem is a lack of inspiration and vision.  As India and China demonstrate space programs that are a point of national pride they will become a more and more appealing career prospect.   As such it will become harder and harder to keep young foreign born engineers from going back to their country of origin.  However, the US lacks any serious goal for aspiring engineers to tackle.

There are inspirations out there, just no one with vision AND money

I’m a fan of space exploration and I think serious exploration - not just toy cars on Mars - would inspire.  But so would serious nano-tech, artificial intelligence, robotics (like Honda’s Asimo), alternative energy, and several other fields.

Instead we have risk averse companies who have reduced their R&D to incremental improvement shops.  The gov is just as risk averse and every satellite/R&D program is just 1 baby step better than the last.  In Aerospace the holy grail is propulsion.  In propulsion we’ve barely invented the wheel let alone an automobile.  Until the X-Prize was won almost no company spent any money on even incrementally better propulsion.  Even today the total dollar amount is a pittance.

If we want to continue to lead the world in technology (and by extension the world economy) then we need to get serious.  We need to choose 1 or 2 major project that can change everything - like alternative energy, Sci-Fi style propulsion, etc.  We need to get serious about real basic scientific research and serious engineering R&D.  You don’t make great leaps forward with risk averse baby steps.

Thankfully there’s at least DARPA, if only we could get about 1000 more of those going…

Here’s the article that inspired this rant:

Source Article

Design Projects

The rest of this post will reference engineering school projects.  However, I believe that most of this is also valid to open ended real world projects.

Many engineering schools require semester design projects.  The design project’s goal is to demonstrate to your professor that you learned the key opints of the class.  Typically, demonstrating these core competencies requires being more explicit and thorough in your analyses than you are naturally inclined to be.

The biggest mistake most people make is to assume the “real” work comes late in the process.  It doesn’t the real work in any successful project is done up front.  Serious effort must be given to the choice of projects.  Even more thought and effort must be put into determining the essence and purpose of the project.  The rest of this post will explore this further.

Design Project - the purpose…

The purpose of any design project is the design of a product which can manufactuered.  But what is the real purpose of the end product?

One common mistake is to assume that your end product must be everything to everyone.  For example, in my senior design project (years and years ago) we designed hardware to help movie studios move their sets around the studio more safely and with fewer people.  The first inclination for the group was to design the hardware be able to move any set the studio might build.

Ultimately this turned out to be ridiculous.  We couldn’t levy requirements back on the studio so we couldn’t keep the studio from attaching delicate items to the set right where we needed our clamps to grab the set.  The end result being that we had to scale back our ambitions such that we were capable of picking up the majority of the sets.

A more subtle mistake, related to this one, is that if 90% of the sets were less than 400 lbs but the remaining 10% could be as heavy as 1000 lbs do you let the 1000 lb sets drive the design?  The answer most of the time is no.

This is why determining the essence of a project is so important.  In industry this is why is takes months to write requirements.  The cost of a design can be driven up and up by any single requirement.  Obviously you’d like to avoid having the cost of the design be driven by a requirement that doesn’t need to be as demanding as it is.  In other words, do you really design hardware to meet the 1000 lb sets if hardware to move 400 lb sets is half as expensive?  or requires half as much analysis?

The lesson…

The lesson in all of this is to boil down the project to its essence.  The previous examples essence was the ability to move most sets more safely with only a couple of people instead of the previous ten.

Since the essence is most sets not all sets we were able to keep the design simple with C-clampes, square tube frame aluminum, and a manually operated jack for lifting the set.  Had our design required the ability to lift 1000 lb sets then we would have need to design the hardware with an electric jack instead of a manual jack.  We also would have had to add twice as many C-clamps meaning twice as many attachment points.

If the design had been for all sets such that we had to avoid delicate parts of the set then we also would have needed to design the hardware with a telescopic arm for the C-clamps.  This would have required a wholesale change to the design for allowing the telescopic positioning and then fastening down those telescopic attachment points.

Electro-Optical Sensors

Electro-Optical (EO) sensors are used in a wide variety of satellite applications.  EO sensors take light energy and turn it into electrical energy.  There are a variety of sensors that do this.  Some image while other provide the centroid of a spot of light.

Scientific imaging is largely done with CCDs.  FPAs can fill the same role as CCDs with many advantages (such as less noise and therefore sensitivity to lower signal levels).  However, fewer people have experience with FPAs the engineering community than CCDs.  Also (I believe) FPAs are more expensive.

LECs and Quad Cells are typically used as position sensors.  LECs use a single photodiode with 4 electrical pickoffs to return the centroid of a spot.  Quad cells use 4 photodiodes each with 1 electical pickoff for centering applications and centroiding applications.  Each sensor returns 4 voltages/currents which are used to calculate the centroid.

Note that for a Quad cell to provide fine resolution centroid information the light spot must be “large” compared to the sensor itself.  A tight light beam (like a laser) creates a small spot and the only information returned is the quadrant where the light is.  A broad light beam where the spot occupies 50% of the sensor face, for example, will create signals from all 4 quadrants for a centroid calculation.

For more information see the Electro-Optical Sensors article on the wiki.

The argument among space enthusiasts…

Space exploration funds are very limited and have been for decades.  I haven’t worked onsite at NASA for years but the last number I remember is something like $15B for NASA’s annual budget.  This sounds like a lot but with the better part of $1B devoted to each Shuttle launch $15B doesn’t last long.

So the classic argument among space enthusiasts is should we bother with human space flight?  It’s far more expensive than robotic space exploration.  Can humans bring enough extra to the mission that it is worth the extra expense and risk?

The risks of human space flight

The most obvious risk to manned space flight is a fiery and most spectacular death.  It is most likely to happen on launch or re-entry.  If we start landing on the surface of other planets then that landing will be risky as will any surface exploration.

When we lose a space vehicle meant for manned space flight we lose people and an extremely expensive vehicle.  The people, at least to date, are very well trained, very intelligent people.  Often they have PhDs in engineering and years if not decades of training.  The vehicle is extraordinarily expensive because of its ability to support human life in space for any significant time duration.  Additionally, there are redundant systems and user interfaces.

Robotics, the cheap and (largely) risk free way to explore space

Robots are cheap.  Robots that are lost in exploration don’t have crying widows; there is no lost human potential.  And robots like Spirit and Opportunity offer glimpses into greatness.  Robots designed to survive months have run around the planet for years despite “injuries” and degraded solar panel performance.

I don’t think proper space exploration can be done without robots.  They allow us to explore without risk to human life.  They provide us with information beyond our own senses.  We spend billions of dollars to send people without spending an extra couple of hundred million on support robots?

Robots are essential but exploration with robots alone misses the point

If I had my druthers I’d work on rovers like Spirit and Opportunity.  I’d work on adding lots and lots of artificial intelligence to them.  How much more area would Spirit and Opportunity cover with smart fault detection and robust automatic use of remaining resources?  How much more area if we could say go here and leave the obstacle avoidance to the rover rather than having to move it a little at a time and wait for the time lag of signals coming back from Mars?

The purpose of exploration is the expansion of the human spirit.  Economically we make exploit the resources of the lands we explore.  From a survival standpoint the farther we spread the less likely we are to be wiped out by war, an asteroid or plague.  Exploring with robots alone doesn’t accomplish any of this.

MEMS Gyro models

MEMS gyroscopes are becoming common in Aerospace systems.  They are small, low power sensors accurate in frequency ranges good for Aerospace applications.  Often, MEMS gyros are the only sensors commerically available that provides the necessary frequency response, mass, power and environmental.

I’ve found 2 types of MEMS gyro modeling.  Both of these modeling types are for the design of the MEMS gyro.  A MEMS gyro sensor requires design of some key parameters - resonant frequency, driving frequency, and quality factor.  These articles are not on the frequency response of the sensor.    The frequency response and noise are the primary items to model for control systems.  So these design articles are high fidelity models and information purposes.

Traditional modeling of MEMS Gyros

Traditional design modeling of MEMS gyros often starts with an FEM of the sensor.  However, the FEM is often too large for feasible modeling.  FEM modeling can be infeasible for memory reasons or simply the length of time it takes to produce results.

The next step in traditional design modeling is to create an equivalent electrical circuit for detailed analysis in various software packages.  Again producing results from these equivalent circuit models is time consuming.

Wiki article on Traditional MEMS Gyro modeling

Simplified lumped parameter model for MEMS Gyros

I found a journal article describing a lumped parameter model for MEMS gyroscope design suitable for running in Simulink.  The  benefit of the Simulink lumped parameter model technique allows for much faster MEMS gyro design results through simple gains and trnsfer function blocks.  The results present in the journal article looked encouraging.

Wiki article on Simplified lumped parameter model for MEMS Gyros

More articles coming…

Accurate sensor models are necessary for any good control loop design.  So I have a couple more sensor model/design articles coming.  After that I will start adding details of MEMS gyros as I find them on the web.

I’ve written an article on the wiki on what I call controller fusion.  I refer to it as controller fusion becuase, like Sensor Fusion, I use filters to blend non-ideal outputs from more than 1 transfer function into 1 output which is closer to the desired output.

For a work proposal on a reaction cancellation mechanism I used a proportional controller for fast response and a PI-Lead controller to drive the steady-state error to 0.  In simple sensor fusion the sensor outputs are filtered and then added together to form a better single output.  In this form of controller fusion I use filters on the error signal to adjust the gain of the controller in real-time.  As a result, PI-Lead output is almost turned off for a step command and the proportional controller output is almost turned off when the system is holding a steady-state value.

I have not had the time to bring this idea to full maturity but I thought it was an interesting enough idea to share.

I love this TV.

My wife and I bought the Samsung 750 52 inch LCD a couple of months ago and we love it.  (The Touch of Color around the bezel sold my wife on the latest, greatest, biggest TV Samsung made.)

The 120 Hz refresh rate is great for sports.  (My son loves baseball and it looks amazing on this TV).  The upconversion this Samsung provides makes even my old DVDs (on a 10 year old DVD player) look great.  The upconverted DVDs don’t look as good as a true HD signal but they look excellent.

Typically I avoid buying the latest, greatest anything because of the huge premium you pay.  However, in this case I think it was money well spent.  We only replace our TV about once every 10 years so why not get the best.  You won’t regret it later.  Also, my parents own a Sharp Aquos.  I’m a fan of Sharp gadgets too but this Samsung makes that Aquos look cheap.

If you are in the market for a new TV, the Samsung 52 inch 750 with Touch of Color and 120 Hz refresh is the one to buy.

New Look Coming Soon…

I recently paid someone to make a real logo for my site.  Additionally, I’ve noticed that the site Header on the wiki has gotten very large.  So large in fact that the content of the page falls off the bottom.  If I was visiting someone else’s site I’d find this very annoying.

So I’ve been working hard to reskin the wiki to incorporate some SEO tricks I’ve learned as well as the new logo.  The primary benefit will be to move some the current wiki Header template text to the page header and the left side.  When I’m done I hope the skin header will be a little shorter than its current height and the wiki Header template size will no more than half its current height.  Check it out as I work on it at the Beta site.

Automatic report generation with MATLAB

For years I’ve had to create reports in Word and PowerPoint.  Unlike Excel, there is no nice, simple, function call for placing text, pictures, and tables into a Word or PowerPoint document.  As a result I, and many other engineers, have wasted countless hours over the years manually inserting pictures, tables, or boilerplate text into reports.

So I’ve created functions - through trial and error because there is no documentation I can find - to accomplish these tasks.  Soon I’ll have a free pdf of the basics.  The free pdf will be followed by a pdf for sale.  The second pdf will cost about $100.  I’ll list out what I’ve discovered (largely through weeks and weeks of trial and error) and include a couple of basic functions.

Soon after the release of these 2 pdfs and freebie automation tools I’ll release a small set of MATLAB automation tools.  The functionality these tools will offer is

• Insert Pictures
• Insert Tables
• Insert Text
• Insert Slides into a PowerPoint Slideshow
• Replace pictures
• Replace Table Contents
• Copy template slides from 1 PowerPoint file to another
• …

Lots of Sensor articles Coming Soon

I’ve contacted sensor manufactuerers and gotten lists of data on their sensors.  With these lists I’ll be creating articles comparing manufactuerer to manufactuerer, lines within a manufactuerer, and individual sensor articles.  Much like a product catalog a lot of the text surrounding the specifications of each sensor would be the same.  However, Google will penalize me for having duplicate content if I do that.  So I’ll have to work around that.

Sensor Fusion

As discussed in the previous blog entry, sensor fusion is used to create one good sensor from at least 2 sensors that are not good enough to meet specifications.  This can be done simply but when real sensors are involved it can also become a bit of a black art requiring a lot of skill and experience.

Simple Sensor Fusion Example

The wiki has an example showing the details of simple sensor fusion.  The simple example has a low frequency sensor with a bandwidth of 20 Hz.  It also included a high frequency sensor with a lower bandwidth of 1 Hz and an upper of 1 kHz.  The sensors are blended using a second order low pass and high pass filter.  Both filters have a bandwidth of 15 Hz.

I hope to eventually create another example with better filters.  I also hope to create another sensor fusion example for sensors with non-ideal transfer functions.

Sensor Fusion or Sensor Blending

Sensors are what provides feedback to a closed loop system.  Sometime you can’t get the sensor characteristics you need.  This happens a lot in the aerospace industry.

When any one sensor cannot provide the necessary feedack then it is time for sensor fusion or sensor blending.  The simplest form of sensor fusion is a matter of two or more sensors which are filtered so that their strengths (good responsivity and low noise) are used while their weaknesses are filtered out.

Often times sensor fusion is nothing more than simple second order low pass or high pass filters with their outputs added together.  This simple fusion allows for two sensors to provide the desired output.

Simple Example of Sensor Fusion

The most simple sensor fusion that I’ve come across is the combination of two angular rate gyroscopes.  The low frequency gyro was good out to a frequency of approximately 20 Hz.  The high frequency gyro was good between 1 and 1000 Hz.  Unfortunately this system was sensitive to frequencies around 5 Hz.

Normally the blending frequency of the sensor fusion would have happened between 1 Hz and 20 Hz based on an analysis of each sensor’s noise and responsivity.  This example system was sensitive to frequencies around 5 Hz which meant that we needed to avoid frequencies between 0.5 Hz and 50 Hz.

The main weakness of the high frequency sensor was phase loss below 1 Hz.  So we designed a filter to extend the low end of the high frequency sensor down to 0.5 Hz.  More difficult to implement than to conceptualize but it takes some practice to do it correctly.

Ideal Sensor vs. Real Sensor

The ideal sensor is typically modeled with a second order system that has a natural frequency equal to the spec bandwidth and a damping of 0.707 or 1.  I default to 0.707.  This leads to a nice flat, unity response for the sensor below the bandwidth.  Real sensors are non-unity below the bandwidth - i.e. the magnitude has some ripple to it.  Sensor ripple around the blending frequency can be very problematic and must be assessed based on the system needs.

Introduction to Sensor Fusion on the Wiki

Here is an article on the wiki on Sensor Fusion.  It is currently a small, simple article that I hope to expand and encourage anyone interested in Sensor Fusion to help me expand.