Got Control? Part 2

Steve Meyer
May 08th, 2008.

So when is a PC (personal computer) a PAC (programmable automation controller) or a PLC (programmable logic controller)? They are all the same. They all have microprocessors. They are all programmable. They are all available with hardware that is rated for industrial environments, shock, vibration, temperature extremes and various other requirements. They are all connected to real world devices such as sensors, switches, etc. They all execute control based on a programmed binary model of a real world manufacturing process.

They have differing abilities in terms of data storage and throughput. In previous generations of PLC and CNC, the memory for those systems was very expensive and early memories were hand wound wire and discrete magnet memory. With the advent of mass manufactured memory for the PC, the industrial platforms have had to engineer hardware with different components to take advantage of competitive costs. A hard disk drive module was available for some PLC systems where extensive process information  was needed.

In today’s market one vendor offers an industrial computer platform that replaces the PLC, the HMI (human to machine interface) and uses a touch screen interface, using the PC platform to reduce control system costs in many applications by doing several functions with the same hardware. Sounds like a Tablet PC engineered for the plant floor. Nothing unreasonable about that.

Some suppliers suggest that applications which require a lot of information to be acquired and stored at the same time as the control system is executing exceeds the bandwidth of the PLC and requires a different kind of control platform. But I’m not sure how to describe that situation exactly, but I would know it when I see it.

For instance if you are making hard disk drive platters, the exact temperature, pressure, time duration and chemical concentration of each plating step may be required to be tagged to each platter. At millions of platters per year that’s a lot of information.

So what describes the need for data? Sometimes its an external regulatory requirement, like the FDA or Department of Agriculture requiring milk producers to record sterilization of facilities or store batch information on pharmaceutical production. Yeah, that sounds like something you would want to keep tabs on in the event of a problem later on, or even as a means of improving plant productivity and machine utilization.

Is it possible that we can describe the need for different control solutions as a function of the bandwidth of the application? Is the speed of the process and the amount of data needed in given timeframe, a means of defining a different model of control? Some information used for traceability is not needed on a real time basis and could theoretically be streamed in a lower speed thread with a different priority. The control application itself might have a higher priority than the data gathering part of the application.  And it can have varying bandwidth within the range of a machine or process operation.

A multi-ton roll of paper for a printing press has much lower bandwidth than chocolate covered candy bars moving down a packaging line at 35 miles an hour. The candy bar wrapper is running so fast, it takes a high speed camera to diagnose problems because it is far quicker than the human eye can discern.

Within the printing operation are registration functions that are required to insure that colored rollers line up in order to make the images from four (or more) different print sources. This registration function is usually far quicker than a normal controller can respond to and is usually handled with a dedicated module that can discriminate at 50 microsecond time frames.

Not only do the two applications have differing bandwidths, but the bandwidth varies from starting conditions to the bandwidth needed at maximum speed.  So maybe by looking at the controls world with an eye toward control system and data requirements as bandwidth propositions, we can construct better boundaries for applying the control system hardware that is available. Just a thought.

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Got Control?

Steve Meyer
May 03rd, 2008.

The modern era of manufacturing is largely an outgrowth of controls. And that migration has had a long history since the relay logic and Computer Numerical Control systems of the 1950’s.  (CNC for any younger readers that might not know what some of these crazy acronyms actually stand for). Would high speed automation of manufacturing be possible without control systems?

Probably not. And since all business is ultimately governed by return on investment, what are the implications on manufacturing processes when control systems cost in the tens of thousands of dollars as they did in the Seventies? Or over time, as the cost of control has decreased, are we justified in putting a controller on everything?

Is the alphabet soup of industrial control the basis of real distinctions in functionality? Or is it a matter of keeping the domain of a particular field of application in the hands of a few suppliers of proprietary solutions? In the early days, I think a lot of new control frontiers were driven by the demands of particular industries, Military and Aerospace applications of CNC’s where speed and precision were required, and high costs were acceptable. This stimulated the creation of a whole universe of equipment which, as with all things electronic, have become more affordable over time.

There’s the SCADA (sequential control and data acquisition) market that has been largely architected by the use of “loop controllers” and PID (proportional, derivative and integral) control models. In an early generation there were mainframe computers talking to remote hardware in process plant applications with huge wiring and infrastructure costs. The amount of time needed for the hardware to respond to changes in the process was a critical concern.

Scada applications seemed very different from PLC (programmable logic controllers) which were the electronic successor to the giant relay logic cabinets of the sixties and seventies. PLC’s promised the ability to do what relays did faster and cheaper and with programmability that would insure the systems were never obsolete. But the PLC’s kept getting faster and cheaper, so it became economically justifiable to replace and update them. And the ladder logic programming language that documented the labyrinth of relays is still the most popular language for programming control systems.

So it was a most peculiar event a few years ago when the new (at the time) Honeywell process controller platform was an Allen Bradley Contrologix. And now, (roughly) seven years later, Rockwell seeks to reinvent itself as a process control supplier.

So excuse me if I wax philosophical, but looking backwards, which you can never do except as you get older, its interesting to see that all the forms of control are based on relatively similar mathematical models of real world systems whose models execute on microprocessor based controllers. And our primary means of performance improvement is throw faster and faster processors at the problems. But processors just keep getting cheaper thanks to those magicians of silicon in the semiconductor industry. So is there a practical limit where the business opportunity is no longer profitable?

And looking forward, where are we headed? More and more applications are becoming data intensive. Many industries are able to solve the mechatronic challenges, control system challenges, but find their business governed more by the data system because of regulatory demands for traceability or the long term data needed to impact the precision of a critical process. Semiconductor, Pharmaceutical, Food and Beverage industry, Aerospace, you name it.

So is it a control system or a computer? What are the real differences? Reliability, speed, resistance to harsh operating conditions? In the early generations of CNC and PLC had very costly memory making data storage impractical. Hard disk drives today are offering 1Gigabyte of storage for 33 cents. So when is a control system a computer by another name? And where are we going over the next 5 to 10 years in the controls arena?

More to come.

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One Size Never Fits All

Steve Meyer
April 19th, 2008.

Sometimes a lot is made of new technology. There is a tendency to talk about the next big thing in whatever field as “The Solution”. But there’s rarely just one solution that works for everyone.

Currently in the “car wars” (a favorite topic, since we are all effected by gasoline prices) many ideas have been advanced as “The Solution”. We heard a lot about bio-fuels reducing our dependency on oil by 30%, but now are primarily contributing to rising food prices. Hydrogen fuel cells will replace gasoline engines, but not anytime soon because we don’t have an infrastructure that can produce hydrogen as a fuel, nor an acceptable means to store it. And so it goes.  This progression of ideas, and attempts to market same, makes the point that there is rarely a single solution that suits everyone.

Historically in the industrial controls field, companies are started because of a new idea. An engineer comes up with a new solution to an old problem, and Viola!, a new business is created. And as someone who knows, no, its really not that easy. The stepping motor gets invented, and a whole new generation of technology gets rolled out into the marketplace. Too bad the original inventor didn’t file for a patent.

But what comes along with new technology is a bias that the new solution will fit every application. And new companies can be very technology centric in their culture. So it came as quite a surprise to me that Festo Corporation, known for decades as one of the leading pneumatics suppliers, entered into the electromechanical arena.

Festo’s new products include stepping motors and leadscrews and linear motors for linear actuation with micron accuracy and speed. All of the new actuators are delivered in the same format of aluminum extrusion housing so that they are compatible with the classic pneumatic products.

And the point is: give customers more choices. Pnuematics offer high speed and high power density, but limited accuracy. So Festo came to the conclusion that not every actuator requirement is best approached with pneumatics. Sometimes complex speed profiles or higher position accuracies make electromechanical solutions a better choice. In addition, the ability to program position and speed parameters make electromechanical systems more convenient, with significant savings in setup and teardown time. A real plus in production environments.

Sounds like real progress to me. Keep the choices coming, customers will take advantage of the options.

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More Mechatronic and Robotic Reflections

Steve Meyer
April 14th, 2008.

The blend of sensors and motion control become crucial in many applications. The dextrous robot hand of recent years cracks eggs like a chef with the aid of sophisticated pressure sensors at the tips of its “fingers”. Check out the Shadow Robot company for some amazing videos of their “air muscle” powered robot hand in action. Lots of interesting work has been done to mimic the human hand. A miracle of grace and efficiency that is hard to duplicate.

Which brings me to the mechatronics relationship. We spend a lot of time in the motion control part of mechatronics designing systems that are based on velocity and position. And this is the context where the “motion control” term is useful, as far as it goes.

In many of the applications we are concerned with, the positioning systems get all the attention. Probably because its more difficult. Positioning tends to be a more “real time” behavior than discrete control systems allow, and so historically, a lot of the hardware used for positioning systems has evolved on its own. (more on this subject later)

But sometimes we have to take a step back from the positioning problem and all its complexities and get perspective on the project goal. Such is the case with many crimping and press fit applications. Position alone simply won’t do. Position is necessary but not sufficient. As with the robot hand, a feeback sensor is needed to determine if proper pressure is being applied to the part.

And that isn’t always obvious, nor is the proper sensor arrangement a simple matter.

If you have to create a machine that crimps a can lid to a can body, there is a required amount of pressure. And the pressure is the most important attribute of the process. The pressure cannot be below a certain value, otherwise the crimp will fail. The pressure cannot be above a certain value, or the part could be damaged and scrapped.

You can implement a pressure strategy a couple of different ways, and the exact method makes a difference. The machine I had to deal with used a brushless dc servo and a lead screw to drive a crimping tool to close the parts to an air-bag igniter. An air bag igniter is a little like a miniature hand grenade, it contains a small explosive charge. So you want to handle it with care.

The engineer who designed the system was using the current values from the drive motor to calculate how much force was applied. In addition, an external load cell underneath the fixture gave a force value to the control system to verify each part. Data was stored in PLC memory and fed to a PC every certain number of units.

But the motion control system software did not have any programming to wait for the value of the load cell and motor current to be checked to insure that right force was applied to each part. So while everything appeared to be working correctly, parts were failing QA. It took quite a while to figure out.

So when you have a production project, make sure you know what the metrics of quality parts are. Make sure they are part of every aspect of the control system, both hardware and software.

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Robots are Mechatronics

Steve Meyer
April 06th, 2008.

Robots are a fun topic. They tease our imagination to wander into the realm of possibilities. Especially when we create film robots with personalities like R2D2, I Robot and the many strange variations of Artificial Intelligence.

And we begin to push the envelope again as to what mechatronics properly consists of. Consider the “loader” in Aliens when Sigourney Weaver starts fighting with the Queen alien. This hydraulic system, once called a “man amplifier” was designed to facilitate moving high loads easily with human dexterity and control.  A number of experimental “exoskeleton” systems are currently under test in the military to help soldiers carry higher loads of equipment in combat situations. Some of these systems are air powered with sophisticated sensors to provide feedback to the user.

Robot challenges have become popular all over the world for High School and College students to compete in “battle” or structured competitions. Students can design using any technical platform and engage experienced mentors to help them with the formidable learning curve of robot design. Sure, if you have an expert for each discipline it would be pretty easy, motors, amplifiers, motor feedback, gear reduction, mechanics and kinematics, control systems, sensors and transducers, power storage and charging, it gets pretty complicated.

Then there’s the intelligence question. What is intelligence? Can we program it? This is a little more difficult to separate out. Many systems exhibit some of the attributes of intelligence because they are able to adapt to their surroundings. As those who have participated in the recent DARPA funded Autonomous Vehicle challenge, navigation and proximity issues can be programmed, but real long distance travel is not easily rendered into programming. To what extent can we program a system to learn from experience? And what will it be able to do once it has? The limits to software are constantly being expanded.

Over the last thirty years progress have been made on many fronts. Practical robot welding systems are available at $55K price range that many manufacturers are able to afford. And they do everything expected of them in terms of productivity, consistency and speed.  Million dollar Surgical robots now exceed the performance of skilled orthopedic surgeons.

I think its an exciting time in our industry in terms of what is possible. Economies of scale, while sometimes slow, are impacting all aspects of mechatronics. I hope the students coming into the field will be able to apply their skills in solving problems and really use their creativity.  On the Big issues and the small.

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Clarity

Steve Meyer
March 30th, 2008.

A national talk-show host I listen to comments “I would rather have clarity than agreement”. I think that is a great platform for discussion. And I approach the blog with the same goal. This posting is an attempt to clarify my previous entry.

I got into the big debate on automobile technology in the 1980’s. It started with a duty cycle chart of engine horsepower and led me to join Unique Mobility in the late 80’s to try and help bring hybrid technology to the California low emission initiative. We were not successful. Primarily because none of the Big 3 automotive companies would agree to supply a vehicle platform for the drivetrain we developed. We did succeed in building a drivetrain for BMW’s EV-1 and EV-2 which were very successful steps along the way.

But the point of my earlier blog was simply to comment on “automobile technology” as the greatest mechatronic challenge of all. You can start with a simple F=ma approach and deal with how much mechanical power must be produced to move the vehicle, which the Big 3 have been messing around with for years. We have cars made out of plastic to reduce vehicle weight (the “m”) in an effort to get lower power solutions which mean more miles per gallon, you know the rest.

We have messed around with engine RPM producing higher speed engines with smaller displacements to get comparable horsepower with better miles per gallon. Various fuel injection schemes to stretch our gasoline dollar, fuel additives, etc. But while I am not an expert on emerging fuel technologies, it doesn’t seem to have gotten us very far. The national fleet average mileage hovers at 20mpg and hasn’t really changed in decades.

My point in mentioning the pneumatic and hydraulic approaches to solving the automobile “crisis” was not to advocate any of the proposed solutions, but simply to observe that there is more than one way to solve the problem. And in fact, that the US fleet of vehicle was historically evenly divided between steam, gasoline and electric. These are facts, not opinions. What is important to the topic of mechatronics is the diversity of solutions being proposed.

If you want to get into the “efficiency” discussion, you have to look at total system efficiency, and at component efficiency at the same time. The energy density of hydrogen is terrible, so you have to compare all the fuel candidates and their respective storage and conversion systems. Methanol reformers might be perfect for buses. Energy density of battery technologies is another huge area. Lead acid is simply too heavy, and in large part led to the demise of the GM EV-1 of the late 80’s. But that is not the point of this discussion.

What should be important to you and me as citizens is that the DOE has spent billions of dollars on “automobile technology” and the only low emission vehicles for sale in the US are made by Japanese manufacturers. Government bureaucracy has taken over large areas of engineering, and possibly because there is no criteria for performance, very little benefit is generated for the consumer/citizen. I have worked for companies that were DOE subcontractors and interviewed with NREL as a vehicle program manager, so its something I am a little familiar with.

The X Prize Foundation’s automotive competition puts this into focus. There are 60 companies, most of them American, who have filed letters of intent to submit working vehicle entries for the 100MPG equivalent goal of the program. The total program awards will be $10M, not the billions spend by the DOE, and none of the entries are from GM, Ford or Chrysler.

I will bet on good old American ingenuity in spite of the odds against them, and I hope I will be in a position to buy one of the products created by these gutsy, dare I say heroic, competitors in the near future.

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The Ultimate Challenge

Steve Meyer
March 23rd, 2008.

Mechatronics is a difficult term. It covers a lot of territory and is, as one comment mentions, almost meaningless because it is so broad. I think the term is mecha- due to the fact that every application is bounded by its mechanical design as a starting point. The -tronics is intended to capture the electronics element as either control or power, and sometimes both.

But mechatronics includes pneumatic and hydraulic systems, and basically anything that moves. And what moves Americans more than our cars? So I return to an earlier comment that the electric car is the Ultimate Mechatronic Challenge.

But it doesn’t have to be electric. Hydraulic systems have traditionally been the highest energy density for application of pure power. Anyone who has seen a back hoe in action realizes how well hydraulics work for high power. The EPA is partnering with Eaton and Peterbuilt to make a clean diesel-hydraulic hybrid that may end up as the fleet vehicle for UPS delivery. Double the mileage and drastically reduced emissions are just part of the package.

Even pneumatic cars have been built with some success. Check out Guy Negre’s MDI company in Luxembourg. Its a controversial solution, but the fact that the demo vehicle is built and running means they have reached a certain level of success. The 5 seater minivan runs 60 miles a day before air is needed, with a forecast selling price of $16,500.

The Th!nk electric is in test in Norway and the new model is expected sell for $30K with lithium batteries from A123 and 120 mile driving range. This would be a fabulous entry into the market if everything works as planned.

The latest effort by the X Prize Foundation is a $10M prize for the best car design that reaches 100mpg or equivalent. There are currently 60 companies with letters of intent to compete. This is where real innovation takes place.

So there are some interesting lessons to be considered;

The vehicle fleet in the US was evenly divided between electric, steam and fuel solution in the teens and twenties. This is because no single technology solution is the right answer for every situation. When Ford’s assembly line process brought the cost of the car down dramatically so that many people could afford it, Rockefeller made a deal to deliver low cost gasoline as the fuel. That’s part of how we got to where we are today. But the real point is we should have a lot of technology choices as consumers.

Mechatronics is never more challenging than when we look at the car as a portable system and try to figure out the best overall solution, balancing the power source, manufacturing cost and overall system efficiency.

Big companies rarely innovate. Ford and GM have lost major ground in the low emission race, putting America’s industry at risk. When you think of all the steel, glass and fabric that goes into a car, there is a lot more at stake that the assembly worker in Detroit.

Government continues to spend hundreds of millions of dollars on R&D that should be the responsibility of the private companies that stand to gain from these efforts. Given the track record of the last 30 years, its hard to argue that Government needs to be involved. I just hope our tax dollars are being spent wisely.

And lastly, the energy question which is a two-part; shouldn’t government’s regulatory role be to insure that oil and natural gas are readily available from domestic sources instead of finding every excuse why we can’t? And how many of our petro-dollars find their way to funding violent anti-American organizations?

Just some things to think about.

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Energy Policy

Steve Meyer
March 14th, 2008.

Americans have been focusing on energy reduction in this country for some time.  In an upcoming article to be published in Design World, I will detail some of the impact of national energy policy on how electric motors should be built, and how they should be used.  The main conclusion of the article from a technical perspective, is that the big energy savings come from control system solutions, not from incremental improvements in electric motors themselves, which the Department of Energy has spent a lot of money pursuing.

It is reasonable that the government concerns itself with how energy is used.  But what is appropriate for implementing policy?  Is it in the national interest to develop better washers and dryers?  better refrigerators? better air conditioning systems?  Or is this the domain of private enterprise?  Business that is for profit and normally makes the investment in product development sometimes gets a hand from government.

The car industry has received huge amounts of money to develop electric and hybrid electric cars for the US market for over 2o years.  Instead of delivering products, US carmakers have abdicated these niche products and today the major sales of hybrid cars are all Japanese.  US car makers are behind the curve and they don’t appear to be making a lot of progress in the direction of becoming serious suppliers.  The Chevy Volt might prove an exception if they can bring the car to production soon.

But energy policy is not exclusively about consumption, its about production.  Governments, primarily state, have regulated the power companies to the point that electricity is relatively scarce in some markets.   This forces the utility to pay people to use less power instead of investing in more capacity.

The same situation in the oil and gas industry.  No new drilling, fewer refineries, mean scarce gasoline supplies and increasing dependence on foreign supplies.

What happened to atomic energy?  The Europeans developed mini-reactors with cores the size of a waste paper basket.  Check out Popular Science back issues for articles on “Pebble Bed” reactors or archived video files on PBS where American representatives of the Nuclear Regulatory Comission sat in reactor control rooms while their German counterparts shut off coolant to the reactor.  These reactors are totally safe because the nuclear fuel is encapsulated in high temperature ceramic.  It can’t over heat and melt down, it can never go critical mass.  Best of all, you can put them in the cities where you need power, no grid and no grid losses.

Let’s rethink energy policy and look for the strategies that increase supply, and decrease system risks (like grid failures) so that we can grow our industry and employment and a stable economy.

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Medicine and Mechatronics

Steve Meyer
March 07th, 2008.

An interesting niche in the mechatronic world is the laboratory automation market.  Applications in this arena can be syringe dispensing of tiny volumes of fluids, automatic dispensing and sampling of chemicals, DNA processing and many other applications.   For the most part, the applications are Cartesian arrays of samples in small wells and single or multiple dispensing devices on a moving head.  The number of samples being managed can be anything from 1 to 96.

The motion is often powered with small stepping motors and a variety of mechanical solutions, some using timing belts and pulleys, some using lead screws, and some using rack and pinion acuation.   It doesn’t look terribly difficult, but the fact is that as throughput demands increase, the motion is much more difficult.  Components that are cantilevered tend to flex and oscillate which can disturb the accuracy of the motion or require settling time between motions.

There are no simple rules for the kinematics of these systems that will make them more efficient.  Next generation throughput is going come with some R&D and increased hardware costs.  And, next generation performance is going to require next generation design tools, which hopefully are on the near horizon.

The motion is not “mission critical” as it would be for a heart/lung machine or other system that involves risk to human life.  So conventional controls are acceptable.   But the emphasis of the equipment is the data that results from the processes.  So a lot of care is taken to insure that the right data is associated with the right sample.   A lot of money is spent on the PC software and hardware to make sure that the data is accurate.

The motion control aspect of this industry is not the primary focus of its engineering efforts.  Some companies are already experiencing limits in what the hardware can do.  So it remains, to get to the next performance plateau, we will need to throw out the handbook of how its been done up to now and start over with a clean sheet of paper.

As with most mechatronic applications, there has to be a change in the mechanical design of the system in order to achieve better throughput.  What that change is, is not immediately obvious or someone would already be doing it.  But that is how the progression takes place.

So we’ll stay involved in the industry and see how the next evolution takes place.

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E Drives Conference

Steve Meyer
March 02nd, 2008.

I was fortunate to attend the E Drives Conference In Atlanta Feb 14 & 15.  The show is an annual gathering of specialty companies involved in mechatronics.  The exhibits and lectures cover magnetic design tools, power electronic modules, control technology, feedback technology and gear reducers.  A lot of cutting edge conversations in the mechatronic world.

The design of motion control components is a difficult balancing act.  Component manufacturers must incorporate a lot of features and functionality in order to address the broadest portion of the market.  For the OEM machinery builder, this often means paying more for a product that exceeds the requirements of a particular application.

It has always been my opinion that most of the available motion control products are very expensive, so I am always on the lookout for technology that offers the potential to reduce price and deliver the right kind of performance.

Two companies at the conference have standout contributions to make.  One is Luminary Micro which makes high performance, low cost control chips.  They are making major inroads displacing the ubiquitous DSP with more processing capability and full Ethernet and Canbus communications  embedded in the same device.  Very cost effective.

The other is Novatorqu, a new company that has broken some performance barriers in the electric motor.   Novatorque’s President John Petro has re-invented the electric motor’s internal architecture making the DC brushless motor smaller, faster and a lot more efficient.  Did I mention lower cost?  Yes, lower cost too.  So much so, that they think they can take on the AC motor cost point in some applications with their technology.

I hope both of these companies will succeed in growing their respective markets and recovering some of the ground we have lost to foreign suppliers.

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