Tongue can drive powered wheelchair

July 9th, 2009

With a huge boost from technology, individuals can now maneuver a powered wheelchair or control a mouse cursor using simple tongue movements.

“This clinical trial has validated that the Tongue Drive system is intuitive and quite simple for individuals with high-level spinal cord injuries to use,” said Maysam Ghovanloo, an assistant professor in the School of Electrical and Computer Engineering at the Georgia Institute of Technology. “Trial participants were able to easily remember and correctly issue tongue commands to play computer games and drive a powered wheelchair around an obstacle course with very little prior training.”

At the annual conference of the Rehabilitation Engineering and Assistive Technology Society of North America on 26 June, the researchers reported the results of the first five clinical trial subjects to use the Tongue Drive system. The trial occurred at the Shepherd Center, an Atlanta-based catastrophic care hospital. The National Science Foundation and the Christopher and Dana Reeve Foundation helped fund the project.

The clinical trial tested the ability of these individuals with tetraplegia, as a result of high-level spinal cord injuries (cervical vertebrae C3-C5), to perform tasks related to computer access and wheelchair navigation using only their tongue movements.

At the beginning of each trial, Ghovanloo attached a small magnet, the size of a grain of rice, to the participant’s tongue with tissue adhesive. An array of magnetic field sensors mounted on wireless headphones worn by the subject was able to detect movement of this magnetic tracer. Through a wireless interface, sensor output signals transmitted to a portable computer located on the wheelchair.

The signals were able to determine in real time the relative motion of the magnet with respect to the array of sensors. This information could then control the movements of the cursor on a computer screen or to substitute for the joystick function in a powered wheelchair.

Ghovanloo chose the tongue to operate the system because unlike hands and feet, which the brain controls through the spinal cord, the tongue directly connects to the brain via a cranial nerve that generally escapes damage in severe spinal cord injuries or neuromuscular diseases.

Before using the Tongue Drive system, the subjects trained the computer to understand how they would like to move their tongues to indicate different commands. A unique set of specific tongue movements resulted for each individual based on the user’s abilities, oral anatomy, and personal preferences. For the first computer test, the user issued commands to move the computer mouse left and right. Using these commands, each subject played a computer game that required moving a paddle horizontally to prevent a ball from hitting the bottom of the screen.

After adding the up and down commands to their repertoire, researchers asked the subjects to move the mouse cursor through an on-screen maze as quickly and accurately as possible.

Then the researchers added two more commands, single and double mouse clicks, to provide the subject with complete mouse functionality. When a randomly selected symbol representing one of the six commands appeared on the computer screen, the subject issued that command within a specified time period. Each subject completed 40 trials for each time period.

After the computer sessions, the subjects were ready for the wheelchair driving exercise. Using forward, backward, right, left, and stop/neutral tongue commands, the subjects maneuvered a powered wheelchair through an obstacle course.

The obstacle course contained 10 turns and was longer than a professional basketball court. Throughout the course, the users had to perform navigation tasks such as making a U-turn, backing up, and fine-tuning the direction of the wheelchair in a limited space. Subjects navigated through the course as fast as they could, while avoiding collisions.

Each subject operated the powered wheelchair using two different control strategies: discrete mode, designed for novice users, and continuous mode for more experienced users. In discrete mode, if the user issued the command to move forward and then wanted to turn right, the user would have to stop the wheelchair before issuing the command to turn right. The default stop command was when the tongue returned to its resting position, bringing the wheelchair to a standstill.

“Discrete mode is a safety feature particularly for novice users, but it reduces the agility of the wheelchair movement,” Ghovanloo said. “In continuous mode, however, the user is allowed to steer the powered wheelchair to the left or right as it is moving forward and backward, thus making it possible to follow a curve.”

Each subject completed the course at least twice using each strategy while the researchers recorded the navigation time and number of collisions. Using discrete control, the average speed for the five subjects was 5.2 meters per minute, and the average number of collisions was 1.8. Using continuous control, the average speed was 7.7 meters per minute, and the average number of collisions was 2.5.

While this initial performance trial only required six tongue commands, the Tongue Drive system can potentially capture a large number of tongue movements, each of which can represent a different user command. The ability to train the system with as many commands as an individual can comfortably remember and having all of the commands available to the user at the same time are significant advantages over the common sip-n-puff device that acts as a simple switch controlled by sucking or blowing through a straw.

Some sip-n-puff users also consider the straw to be a symbol of their disability. Since Tongue Drive users simply wear headphones, which is common when listening to music, the system is more acceptable to potential users.

“The Tongue Drive system seems to be much more supportable if there were a failure of some component within the system,” said John Anschutz, manager of the assistive technology program at the Shepherd Center. “With the old tongue-touch keypad, if the system went down then the user lost all of the functions of the wheelchair, phone, computer, and environmental control. Ghovanloo’s approach should be much more repairable should a fault arise, which is critical for systems for which so much function is depended upon.”

A future system upgrade will be to move the sensors inside the user’s mouth, according to Ghovanloo. This will be an important step for users who are very impaired and cannot reposition the system for best results, Anschutz said.

“All of the subjects successfully completed the computer and powered wheelchair navigation tasks with their tongues without difficulty, which demonstrates that the Tongue Drive system can potentially provide individuals unable to move their arms and hands with effective control over a wide variety of devices they use in their daily lives,” Ghovanloo said.

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Solar cell costs coming down

July 9th, 2009

Solar power’s heavy cost continues to be the downside to any kind of growth as a potential energy source.

By thinking differently, that may soon change. Today’s solar industry mainly produces solar panels made from crystalline silicon, which is relatively expensive.

However, new players in the solar industry have instead been looking at panels that can harvest energy with copper-indium-gallium-selenide (CIGS) or CIGS-related materials. CIGS panels have a high-efficiency potential, may be cheaper to produce, and would use less raw materials than silicon solar panels. That is the upside. The downside is manufacturing of CIGS panels on a commercial scale has thus far proven to be difficult.

There is now a low-cost solution processing method in development for CIGS-based solar cells that could provide an answer to the manufacturing issue, said Yang Yang, a professor at the UCLA Henry Samueli School of Engineering and Applied Science.

“This CIGS-based material can demonstrate very high efficiency,” said William Hou, a graduate student on Yang’s team and first author of a study on the subject. “People have already demonstrated efficiency levels of up to 20%, but the current processing method is costly. Ultimately, the cost of fabricating the product makes it difficult to be competitive with current grid prices. However, with the solution process that we recently developed, we can inherently reach the same efficiency levels and bring the cost of manufacturing down quite significantly.”

The copper-indium-diselenide thin-film solar cell developed by Yang’s team achieved 7.5% efficiency in the published study but has in a short amount of time already improved to 9.13% in the lab.

“We started this process 16 months ago from ground zero. We spent three to four months getting the material to reach 1%, and today it’s around 9%. That is about an average increase of 1% every two months,” said Yang.

Currently, researchers manufacture most CIGS solar cells using vacuum evaporation techniques called co-evaporation, which can be costly and time-consuming. The active elements, copper, indium, gallium, and selenide, heat up and go onto a surface in a vacuum. Using vacuum processing to create CIGS films with uniform composition on a large scale has also been challenging.

The copper-indium-diselenide material created by Yang’s team does not need to go through the vacuum evaporation process. Their material simply dissolves into a liquid, then they apply it and bake it. To prepare the solution, Yang’s team used hydrazine as the solvent to dissolve copper sulfide and indium selenide in order to form the constituents for the copper-indium-diselenide material. In solar cells, the “absorber layer” (either copper-indium-diselenide or CIGS) is the most critical to performance and the most difficult to control. Researchers can take the copper-indium-diselenide layer, which is in solution form, and paint or coat it evenly onto a surface and bake it.

“In our method, material utilization is one advantage. Another advantage is our solution technology has the potential to be fabricated in a continuous roll-to-roll process. Both are important breakthroughs in terms of cost,” Hou said.

The team’s goal is to reach an efficiency level of 15 to 20%. Yang predicts three to four years before commercialization.

“As we continue to work on enhancing the performance and efficiency of the solar cells, we also look forward to opportunities to collaborate with industry in order to develop this technology further,” Yang said. “We hope this technology will lead to a new green energy company in the U.S., especially here in California so that it may also bring job opportunities to many who need it.”

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Wind project in holding pattern

July 9th, 2009

The world’s biggest wind farm located in the Texas Panhandle is now on hold.

Texas oil billionaire T. Boone Pickens said the wind farm project fell apart partly because of the lack of adequate transmission lines to carry the electricity from remote locations to cities, according to a published report.

The oil tycoon had hoped to build new transmission lines but could not secure financing.

While this changes things quite a bit, Pickens still plans to use the turbines he ordered for the project.

Pickens had already ordered 687 large wind turbines from General Electric, starting in 2011. The problem came about when transmission lines built by the state were not going to reach the location he has leased until 2013, so he needed to put the turbines elsewhere. At one point, Pickens said he would build his own transmission lines, but difficulty in finding financing during the credit crunch affecting the nation forced him to shelve that plan.

Possible locations for the 687 turbines include Wisconsin, Oklahoma, Kansas, Texas, and Alberta, Canada, Pickens said. Collectively, at a capacity of 1,000 megawatts, which is the size of the power generated from a nuclear plant, this would still amount to a substantial investment in wind power. On the other hand, the Panhandle project power projections came in at 4,000 megawatts.

“We’re going to be active in the business,” Pickens said. “It’s not that we’ve gotten out of the business or anything like that.”

For related information, go to www.isa.org/environment.

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Allen Bradley Allen Bradley Allen Bradley

May 22nd, 2009

That seems to be the name name in PLCs in the USA. Allen Bradley Allen Bradley Allen Bradley is all we hear now. Does anyone still use Modicon or Siemens PLCs? How about Square D or Omron or Mitsubishi? Any old TI users still out there? I would like to hear from you. Allen Bradley does make some very high quality plcs and controls. They have about 60% of the US market for plcs I believe.

Bill

www.tek-supply.com

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Allen Bradley SLC 500 Sale.

May 22nd, 2009

Just wanted to let everyone know that the PLC Superstore is having a Spring Allen Bradley sale. Thru the end of June we are offering a 10% discount from our already low prices on reconditioned Allen Bradley PLCs.

Visit our web site at: www.tek-supply.com for great deals on Allen Bradley automation products.

Also visit www.plcsuperstore.com and www.allenbradleyplc.net for more savings on Allen Bradley controls and plcs.

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U.S. manufacturing slides

March 6th, 2009

New orders, production, employment, and inventories are contracting while prices are falling.

The Institute of Supply Management reported its February numbers this week.

Norbert J. Ore, chair of the ISM Manufacturing Business Survey Committee said, “Manufacturing continues to decline at a rapid rate in February. While production has slowed its rate of decline, employment continues to fall precipitously. Prices continue to decline, but price advantages are not sufficient to overcome manufacturers’ apparent loss of demand. Survey respondents appear generally pessimistic about recovery in 2009. Some express hope that the stimulus package will help their industry.”

Some anecdotal responses:

  • “Customers across the board are being very cautious about ordering any stock.” (Transportation Equipment)
  • “Business is very slow, some of which is due to seasonality, and some is due to the state of the economy.” (Chemical Products)
  • “Asia previously was over 50% of our business and is now close to zero.” (Machinery)
  • “Still seeing frequent attempts at increases while everything is reacting to an economy that is retracting.” (Food, Beverage & Tobacco Products)
  • “Business slightly improved in February. May be the result of inventories finally coming into balance with lower demand.” (Paper Products)

MANUFACTURING AT A GLANCE
FEBRUARY 2009

Index

Series
Index
February

Series
Index
January

Percentage
Point
Change

Direction

Rate
of
Change


Trend*
(Months)
PMI

35.8

35.6

+0.2

Contracting

Slower

13
New Orders

33.1

33.2

-0.1

Contracting

Faster

15
Production

36.3

32.1

+4.2

Contracting

Slower

6
Employment

26.1

29.9

-3.8

Contracting

Faster

7
Supplier Deliveries

46.7

45.3

+1.4

Faster

Slower

5
Inventories

37.0

37.5

-0.5

Contracting

Faster

34
Customers’ Inventories

51.0

55.5

-4.5

Too High

Slower

7
Prices

29.0

29.0

0

Decreasing

Same

5
Backlog of Orders

31.0

29.5

+1.5

Contracting

Slower

10
Exports

37.5

37.5

0

Contracting

Same

5
Imports

32.0

36.5

-4.5

Contracting

Faster

13

OVERALL ECONOMY

Contracting

Slower

5

Manufacturing Sector

Contracting

Slower

13

*Number of months moving in current direction.

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Manufacturing summit invokes change

March 6th, 2009

“The grand challenge [of engineering today] is primarily about human ingenuity and technology,” said Lincoln Pratson, associate professor of sedimentary geology at the Nicholas School for the Earth and the Environment at Duke University and one of the panel members on energy during this week’s National Academy of Engineering’s Grand Challenges Summit in Durham, N.C. “Engineers are well positioned to lead our energy revolution. But we’ll need leaders from all walks of life, business, government, law, and policy,” he said. “In the case of 21st Century energy, special opportunities exist for those who can communicate with those from other fields.”

Pratson’s idea was one of the main challenges leaders discussed throughout the two-day event, the result of a partnership between Duke University, Olin College, and University of Southern California, in which engineering experts, professors, and business professionals from across the country shared their views on how the industry will meet the 14 grand challenges engineers face for the future.

The challenges fall under four main groups—sustainability and the environment, the role of engineering in improving medicine and healthcare delivery, enhancing security by reducing human vulnerability from human-made and natural threats, and enhancing the human capability for joy.

The challenges themselves range from making solar energy economical, providing energy from fusion, developing carbon sequestration methods, and providing clean water across the world to advancing health informatics, better engineering medicines, and preventing chemical and biological warfare and nuclear terror. Other challenges include enhancing virtual reality, advancing personalized learning, and engineering the tools of scientific discovery.

The challenges did not stop at science and technology. Entrepreneurs shared their knowledge about how to sell these grand ideas to businesses and policy makers, reinforcing the notion that engineering is not just for hermetic techno-geeks, but an all-encompassing career choice for innovative, business-minded, creative thinkers who are excited to take on the challenge of changing the world they live in for the better.

“The aspiration of energy independence of any country is very lofty and almost impossible to achieve,” said Emil Jacobs, ExxonMobil’s vice president of research and development and one of the energy panel members. “The target we should have is energy security—the ability to have the energy you need to support economic development. … There’s not a silver bullet here. We’ll need every option available—coal, natural gas, oil, biofuel, nuclear, soil, and wind. Technology will be a key component. If we look at the mix between these, it’s hard to see what that will look like. You need to think about scale, cost, sustainability, and environmental footprint.”

“The term [energy independence] is my least favorite phrase,” said Robert Socolow, professor at the Princeton Environmental Institute at Princeton University. “It implies if we take care of ourselves it doesn’t matter what the rest of the world’s problems are. I can’t figure out why it has political appeal as a concept except there’s a side of us that wants to believe that. If we were import-free from oil, but the rest of the world were full of international relations that could go awry, do you think we’d be insulated from that? It’s too bad, it’s a political trough we all walked into from the 1970s, and we seem to not be able to climb out of it.”

Inciting engineers to be harbingers of technological innovation and scientific philanthropy were the beef stock of the summit, but definite aromas of educational metamorphosis drifted throughout the two days as engineering leaders trumpeted the notion that universities will need to be knowledge brokers as well as local and federal policy makes in industry to solve these vast problems.

“This is a time of great openness of change to our nation and the world,” said Duke University’s Dean of Engineering Tom Katsouleas during the summit’s opening remarks. “But the doorway to change will not remain open long. We need to put in place institutional changes to allow us to sustain efforts when openness to change has abated. University leaders will need to be engaged … committing themselves to research and work that fosters and rewards collaboration and teamwork across disciplines,” he said.

“They’ll need to be active thought leaders to inform the public of challenges and obstacles,” he said, which does not mean being just a researcher for faculty, but inspiring students. “We need to change the way we teach in the classroom, encouraging students to step outside their comfort zones and make them aware of how they impact the human condition.”

—Ellen Fussell Policastro

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Unconventional thinking could boost solar cells

February 26th, 2009

Unconventional thinking could boost solar cells

There is an old saying about not rocking the boat; but when it comes to hiking the capabilities of solar energy, the opposite is true.

Unconventional solar cell materials, much less costly than silicon and other semiconductors in use today, could substantially reduce the cost of solar photovoltaics, according to a new study from the Energy and Resources Group and the Department of Chemistry at the University of California, Berkeley, and the Lawrence Berkeley National Laboratory (LBNL).

These materials, some of which are highly abundant, could expand the potential for solar cells to become a significant source of low-carbon energy across the world, according to the study authors.

The analysis examines the two most pressing challenges to large-scale deployment of solar photovoltaics as the world moves toward a carbon neutral future: cost per kilowatt hour and total resource abundance.

The UC Berkeley study evaluated 23 promising semiconducting materials and discovered 12 are abundant enough to meet or exceed annual worldwide energy demand. Of those 12, nine have a significant raw material cost reduction over traditional crystalline silicon, the most widely used photovoltaic material in mass production.

The work provides potential for research into novel solar cell types just at a time when the U.S. Department of Energy and other agencies plan to expand the use of clean energy, said Daniel Kammen, UC Berkeley professor of energy and resources and director of the Renewable and Appropriate Energy Laboratory.

Kammen and colleagues Cyrus Wadia of LBNL and A. Paul Alivisatos of UC Berkeley’s Department of Chemistry embarked on an intensive research project to explore the question if high-impact materials have been overlooked or underdeveloped during the last several decades of solar cell research.

“The reason we started looking at new materials is because people often assume solar will be the dominant energy source of the future,” said Wadia, a post-doctoral researcher who spearheaded the research. “Because the sun is the Earth’s most reliable and plentiful resource, solar definitely has that potential, but current solar technology may not get us there in a timeframe that is meaningful, if at all. It’s important to be optimistic, but when considering the practicalities of a solar-dominated energy system, we must turn our attention back to basic science research if we are to solve the problem.”

The most popular solar materials in use today are silicon and thin films made of CdTe (cadmium telluride) and CIGS (copper indium gallium selenide). While these materials have helped elevate solar to a major player in renewable energy markets, they still suffer from manufacturing challenges. Silicon is expensive to process and mass produce. Furthermore, it has become increasingly difficult to mine enough silicon to meet ever-growing consumer demand.

Thin films, while significantly less costly than silicon and easier to mass produce, would rapidly deplete our natural resources if these technologies were to scale to terawatt hours of annual manufacturing production. A terawatt hour is a billion kilowatt hours.

“We believe in a portfolio of technologies and therefore continue to support the commercial development of all photovoltaic technologies,” Kammen said. “Yet, what we’ve found is that some leading thin films may be difficult to scale as high as global electricity consumption.”

“It’s not to say that these materials won’t play a significant role,” Wadia added, “but rather, if our objective is to supply the majority of electricity in this way, we must quickly consider alternative materials that are Earth-abundant, non-toxic and cheap. These are the materials that can get us to our goals more rapidly.”

The team identified a large material extraction cost (cents/watt) gap between leading thin film materials and a number of unconventional solar cell candidates, including iron pyrite, copper sulfide, and copper oxide. They showed iron pyrite is several orders of magnitude better than any alternative on important metrics of both cost and abundance. In the report, the team referenced advances in nanoscale science to argue they could offset the modest efficiency losses of unconventional solar cell materials by the potential for scaling up while saving significantly on materials costs.

Finding an affordable electricity supply is essential for meeting basic human needs, Kammen said, yet 30% of the world’s population remains without reliable or sufficient electrical energy. Scientific forecasts predict to meet the world’s energy demands by 2050, global carbon emissions would have to grow to levels of irreversible consequences.

“As the U.S. envisions a clean energy future consistent with the vision outlined by President Obama, it is exciting that the range of promising solar cell materials is expanding, ideally just as a national renewable energy strategy takes shape,” said Kammen, who is co-director of the Berkeley Institute of the Environment and UC Berkeley’s Class of 1935 Distinguished Chair of Energy.

For related information, go to www.isa.org/manufacturing_automation.

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Tenn. wins bid for German chemical plant

February 26th, 2009

With the demand for solar energy product on the rise, Munich, Germany-based Wacker Chemie AG said today they plan to build a $1 billion factory in Cleveland, Tenn., that will produce hyperpure polycrystalline silicon, a component used to build solar panels and semiconductors.

The facility, which Wacker purchased for $20 million, will be on a 550-acre greenfield site near the Hiwassee Industrial Park in the Charleston community of Bradley County. There will be an extensive design period and work in process before construction begins. The plan calls for Wacker to create 500 jobs at the factory.

Wacker Chemie is the world’s second largest producer of hyperpure polycrystalline silicon. Wacker has manufactured polysilicon for over 50 years and has steadily expanded its capacity to meet rising solar-silicon demand in the photovoltaic industry.

“We expect that the demand from the semiconductor and photovoltaics industries will increase over the years ahead,” said Wacker Chemie Chief Executive Wolfgang Staudigl. He said they selected the Tennessee location for its good infrastructure as well as for the support the company had experienced through local authorities and business partners.

In addition to garnering up to $50 million in incentives from Bradley County commissioners, another reason Wacker wanted to move across the pond was electricity costs in Tennessee are 50% cheaper than that found in Germany, where Wacker currently operates polysilicon plants. In addition, Wacker said it would have an over-the-fence supply of chlorine from an adjacent OLIN Corporation facility.

Tennessee is on a roll as this the third $1 billion project unveiled in the past eight months. The other two were a Volkswagen plant near Chattanooga and Hemlock Semiconductor Corp. facility that will produce hyperpure polycrystalline silicon near Clarksville.

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Factory automation safety networks are emerging as the next competitive battleground in the automation

February 26th, 2009

Factory automation safety networks are emerging as the next competitive battleground in the automation network wars. Drawing on legacy battles in areas such as serial-based device networks, process fieldbuses, and Ethernet-based automation networks, suppliers and network trade associations alike are ramping up their arsenals for competition in this increasingly important arena. This race will fuel growth in the worldwide market for factory automation safety networks at a compounded annual growth rate (CAGR) of 39.3% over the next five years. The market totaled less than 700 thousand nodes in 2008, a figure that is forecast to grow to over 3.6 million in 2013, according to a new ARC Advisory Group study.

Factory“The safety network market will benefit from the same quantifiable cost savings in areas such as wiring and installation that fueled adoption of standard device networks over hard wiring, plus they can deliver concrete business benefits in areas such as regulatory compliance and reduced shutdowns. The timing and impact of safety regulations remains a wild card in many parts of the world, but both existing suppliers and new entrants are lining up their safety network strategies as the technology increasingly emerges as a key differentiator,” according to Vice President Chantal Polsonetti, the principal author of ARC’s “Factory Automation Safety Networks Worldwide Outlook”.

Cost Savings versus Hard Wiring
Growth in the safety network market will parallel that of serial-based device networks from the perspective of the wiring savings a bus-based network can deliver relative to hard wiring of safety components. These savings are realized in areas such as reduced cable costs, smaller panels and cable trays, fewer components required, reduced cost of wire installation, and greater flexibility in reconfiguring the network as operations dictate. Increasing availability of light curtains, safety switches, and other safe components with a network interface will only further the potential cost savings in this area. Growth in interest in wireless safety devices will further fuel cabling and installation savings.

Reduced Downtime through Isolated or Controlled Shutdowns
Limiting the operational impact of a safety event is another business benefit derived from use of safety networks. Ability to implement controlled or isolated shutdowns by decelerating motors or isolating emergency stops to specific zones has significant benefits relative to tripped E-stops or light curtains initiating complete system shutdowns and often time-consuming restarts. Servo drive manufacturers have already recognized this trend and are moving toward integrated safety network components for their drive systems that allow controlled or limited shutdowns.

Safe Motion Fuels Growth in Motion Control
Integration of safety functionality into servo drives and other motion control equipment is one of the most intriguing drivers in the factory automation safety marketplace. Embedding a safety controller and safe I/O right into a servo drive with a soft starter eliminates the need for a separate safety controller and I/O. Safety functions are integrated directly into the drive, eliminating the need for external power contactors and speed monitoring equipment and enabling local control.

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