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Articles from 2013 In April


Video: MakeVR Attempts to Create a Natural HMI

Video: MakeVR Attempts to Create a Natural HMI

Working on a CAD drawing all night may look very different in the near future. In the next few years, you likely will be able to design not only objects but also entire worlds in three-dimensional virtual reality. One of the 3D CAD packages taking the lead in this transformation is MakeVR, a content-creating application developed by Sixense and demonstrated at this year's Game Developers Conference.

At GDC 2013, the system was displayed using a Samsung 3D TV. MakeVR has been adapted to be used with the Razer Hydra controller, a two-hand interface that offers six degrees of freedom as it registers movements in all directions. Users create and manipulate objects, change perspective within the virtual space, and access tool kits and menus with gestures, rather than stretching for a mouse or keyboard.

Just as exciting is the paring of the software with head-mounted displays (HMDs). The team at Sixense, lead by Paul Mlyniec, designed the software with HMDs in mind, and the designers have already managed to get MakeVR to work on the Oculus Rift display.

The Razer Hydra controller offers acute sensitivity and precision -- great for precision design and 3D printing -- but it takes some time to get used to an HMD. The virtual depth perception facilitates controls; it also immerses you in a world of design and exploration. You can import and fully integrate objects from other 3D CAD packages, as well as produce .stl files for 3D printing.

The technology is accessible enough that it will affect us sooner rather than later. The Sixense team envisions a virtual world where a community can share libraries of objects, and entire worlds can be created and explored with friends -- a type of gamification of the design environment. The company says in the video below that a soon-to-be-launched Kickstarter campaign will fund the developments of these features.

The system is at its alpha stage, but the team plans to continue developing tools, create an online object and world repository, develop physics for the platform, and create a collaborative, multi-player platform. It also plans support for depth cameras and other devices.

The system has been in development for three years. Keep an eye on MakeVR and systems like it working to start a trend.

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Charting the Failure History of a Bolt

Charting the Failure History of a Bolt

I was working on a product with a gearbox. A two-inch-long bolt in the gearbox broke and jammed things up when the bolt head engaged with a lightening hole in one of the gears. The bolt broke with a very flat fracture at the first loaded thread, no shear lip, no beach waves, so I thought it was due to high-cycle fatigue.

I asked around and discovered that the same bolt had failed years before a few times. They solved the problem by increasing the installation torque. That kept the problem from happening again for a number of years. I gathered the reports written by the engineers who worked on the problem previously.

I calculated the first and second bending mode frequencies for the bolt and found the second mode frequency was pretty close to that of an adjacent gear mesh frequency. I was able to identify fretting on some bolts where the second bending mode had the iron-based bolt hitting the light alloy case at the antinodes. The previous study of the problem had included running the bolt with strain gages, and I was able to retrieve the magnetic tape data.

The previous study had reported on the normal operating stresses, which were deemed acceptable and matched that of a main power transmission gear mesh frequency. The gear I suspected was an accessory gear adjacent to the bolt failure locations. I took the magnetic tape data, and instead of looking at the steady state data, asked that the data be reduced into waterfall plots (amplitude vs. frequency vs. time) starting right from start-up.

Those plots revealed that as the alloy gearbox case material warmed up, it brought the second bending mode frequency of the bolt into a perfect match with the accessory gear mesh frequency, so there was a relatively brief period during warm-up where the strain was very high. Fatigue cycles add up pretty fast when the frequency is 20+ kHz.

I recommended removing the Iron-based full ground shank diameter bolt with machined threads, and replacing it with a Nickel Superalloy bolt with a pitch diameter shank and rolled threads. This gave a huge shift in the bolt frequency away from the excitation, a huge increase in strength and toughness, a huge increase in the clamping strain energy, and a weight decrease. Problem solved in fairly short order. Sometimes less is better.

This entry was submitted by Oscar Carlson and edited by Rob Spiegel.

Oscar Carlson is a retired mechanical engineer.

Tell us your experience in solving a knotty engineering problem. Send stories to Rob Spiegel for Sherlock Ohms.

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Mobile Technology’s Influence on Data Acquisition

Mobile Technology’s Influence on Data Acquisition

Industrial users are starting to expect mobile access to measurement data, according to an article on mobile technology that is part of the recently released "Data Acquisition Technology Outlook 2013" report from National Instruments (registration required).

The report states:

The worldwide proliferation of mobile devices has given people unlimited and instant access to information. Questions no longer go unanswered, as information is made available from anywhere, anytime. Mobile technology has created a natural expectation to have continuous access to information and it is now influencing the data acquisition market.

The report also quotes Jessy Cavazos, industry director for test and measurement at the consulting firm Frost & Sullivan:

Mobile computing devices are evolving and providing opportunities for wireless data acquisition systems. This is going to change the data acquisition market.

Though we may not be surprised by this trend or even by that bold prediction, they do raise questions about the impact of mobile technology on data acquisition methods and tools. In the data acquisition space, engineers are getting constant access to information, and they are using that access to achieve efficiency gains and in many cases avoid issues before they become costly. But mobile technology is also evolving quickly, so it is difficult to implement standards. The report concludes that engineers and scientists must enhance their skill sets by understanding the options for mobile integration and keeping tabs on the outlook for future mobile systems.

The article, "Mobile Technology's Influence on Data Acquisition," looks at, among other things, how recent platform developments are affecting test and measurement. The report highlights measurement options for mobile technology integration and how common solutions are starting to evolve. The most basic solution is using a mobile device to take handheld measurements, but another is to use the mobile device as a human-machine interface for remote measurement systems. Mobile security, one of the final topics covered in the report, has become an issue as more devices are used to connect to secure information.

The complete 20-page report presents a series of four articles that explore software and hardware technology trends impacting the data acquisition market. It is a must-read and a valuable resource, especially for those directly involved in data acquisition applications.

The other articles that are part of the report are:

  • Big Analog Data and Data Acquisition: "Differentiation is no longer about who can collect the most data; it's about who can quickly make sense of the data they collect."
  • Moore's Law at Work in Data Logging: "With the digital world we live in becoming more complex, we are demanding more from the systems recording the physical and electrical phenomena of today and tomorrow."
  • Emerging Bus Technologies: "New bus technologies are poised to evolve data acquisition systems and address the challenges of future measurement applications."

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Researchers Harvest Energy From Planes

Researchers Harvest Energy From Planes

Researchers are increasingly looking for new ways to provide energy for low-power devices like wireless sensors without using batteries. One new way is by harvesting energy from other sources. Recently, a team of Viennese researchers came up with a way to harvest energy from airplanes to power sensors attached to a plane's fuselage that can be used to monitor and collect data on aircraft structural health.

Researchers from the Vienna University of Technology, working with EADS Innovation Works, have developed and tested a thermoelectric Energy Harvesting Module that can leverage the temperature difference created when a plane takes off and lands, creating energy for nodes on the sensors. The sensors will be used to augment the high cost of maintenance on aircrafts by providing continuous monitoring of a craft, and transmitting that data to its maintenance system, researchers said.

"Such a system obviously has major advantages; however, the main problem lies in the energy supply," said Prof. Ulrich Schmid from Vienna University of Technology's Institute of Sensor and Actuator Systems, in a news release.

Providing an energy source to the sensors is a challenge because "conventional batteries are not designed for such large temperature difference to which an aircraft is continuously exposed during operation," he said. And using cabling to provide a power supply would unnecessarily weigh down an airplane.

Schmid and his team found a way to leverage the same temperature difference that occurs on the plane's fuselage (that creates a challenging environment for conventional batteries) to create an energy harvester. Using a phenomenon called "Seebeck effect" that creates an electrical voltage when two different electrically conductive materials join at contact points with different temperatures, the team used a water-based process to create a harvester to generate enough electricity for the fuselage sensors.

Schmid described the design of the energy harvester in this way:

    We can make optimal use of these temperature gradients by attaching a small thermal mass to one side of the thermoelectric generator. A water reservoir of about 10 cubic centimeters freezes during take-off. It cools down at a slower rate than the fuselage, thus a thermoelectric generator located between these components creates electricity from that temperature difference.

During an aircraft's landing, the process is reversed, with the fuselage temperature becoming warmer than the water reservoir, thus creating energy again, he said. To compensate for the varied time difference in the harvester's voltage output, researchers developed a low-power management system to keep the voltage levels constant and at the appropriate level for the sensors.

The team recently completed successful tests of the sensors on an Airbus aircraft, obtaining 23 joules of energy per flight -- enough to power up the wireless sensor nodes. The scientists are currently looking into alternative materials to the water used in the generator to see if something else might be more suitable, particularly for flight routes that go through very cold regions and may have different temperature considerations.

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Gadget Freak Case #239: Bridge Rectifier Eliminates LED Light Flicker

When I converted my holiday lights from incandescent mini-lights to LEDs, my wife and daughter did not want them in the house. That was a surprise. They're both visual people, and I thought they would like the vivid colors of the LEDs. At first, they did, but soon they complained the flickering LEDs gave them headaches. Eventually, I noticed the flicker and knew the cause: 60Hz line power. Even if you cannot see the flicker, your eyes might detect it -- with ill effect.

By rectifying the AC line power with a full-wave bridge rectifier and using its output to power the strings, I eliminated the flicker.

This simple gadget comprises an off-the-shelf bridge rectifier that converts the 120V AC line current that swings between positive and negative voltages to pulsating direct current for the LEDs. Most LED strings used for holiday or festivity lighting work with the rectified current. The DC power produces a brighter light without any discernible flicker.

You may connect other LED strings to the end of the first string, but don't exceed the current rating of the bridge rectifier. The one listed in the bill of materials has a four-ampere forward-current limit. A string of 50 LEDs dissipates about 4W of energy, which converts to a current of 30-40mA. So you can connect many strings, one after the other.

I have made many of these flicker-eliminating gadgets with various wire lengths wrapped with colored tape appropriate for a given occasion. I use them indoors and outside on circuits protected by a ground-fault interrupter.

One you plug the gadget into a wall outlet, you can plug your LED string into the female receptacle.

Do you have a Gadget Freak project you would like the world to see? Send a brief description of your gadget and a photo to Senior Editor Rob Spiegel.

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The editors of Design News have handpicked your favorite Gadget Freak cases from over the years, bringing them together in a dynamic digital edition, complete with videos, which you can view here.

Gadget Freak Case #239: Bridge Rectifier Eliminates LED Light Flicker

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Aircraft Engine Maker Opens Additive Manufacturing Lab

Aircraft Engine Maker Opens Additive Manufacturing Lab

This month, we told you about a Lux Research report on the future of 3D printing and additive manufacturing (AM). That report said business relationships among AM machine makers and users will need to change as large manufacturers bring these technologies in-house and work to increase control over materials and processes.

We also speculated about whether some manufacturers with specialized needs might bring 3D printing and other AM techniques under their control by outright acquisition, investment, or other types of monetary support. We're still waiting on that, but the aircraft engine maker Pratt & Whitney has opened a lab at the University of Connecticut that will use two different technologies to advance R&D for AM processes that produce metals.

Tom Prete, vice president of engineering for Pratt & Whitney, told us in an email that the lab will use electron beam melting (EBM) machines from Arcam and laser sintering from EOS. Pratt & Whitney is already using AM for prototyping for various engines, including its PurePower engines. Components have been made and engine-tested and are being certified for the PurePower engine family.

The Pratt & Whitney Additive Manufacturing Innovation Center will focus on fundamental R&D in manufacturing and materials science and will be able to produce prototypes, he said.

The facility will be used to help accelerate development of cutting-edge additive manufacturing technologies. Some of these R&D activities include process development, materials development, and post-process development.

AM will "enable new, innovative designs with better performance and lighter weight that can't be made through conventional methods." The center is working with nickel and titanium alloys and plans to bring in other materials as the need arises.

According to a brochure we received about the center, it will use two EBM A2X machines from Arcam and an EOSINT M270 laser sintering system from EOS. The EOS systems are for making tooling inserts, prototype parts, and end products in metal. The Arcam machines will be used to manufacture large, complex parts from a variety of metals that must be processed at high temperatures. A CNC wire electrical discharge machining system will handle post-processing tasks such as removing parts from the build plate and finishing machining.

Arcam says on its website that its A2 and A2X machines are designed specifically for the aerospace industry. Its EBM process produces components that have better material properties than cast metal parts and are comparable to wrought metal parts, because the high-temperature process occurs in a controlled vacuum. The process uses multiple beams and melt pools to speed production. We've reported on other aerospace manufacturers using electron beam AM techniques, including Sciaky, which is building jet fighter wing boxes for Lockheed.

Pratt & Whitney, whose headquarters are in Connecticut, said in a press release that it has invested more than $4.5 million in the center and plans to invest $3.5 million more by 2018. Prete said UTC (Pratt & Whitney's parent) and the University of Connecticut are members of the National Additive Manufacturing Innovation Institute, and the company plans to submit proposals to the NAMII through the center.

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Video Blog: We May Be Geeks, but We Control the World

Video Blog: We May Be Geeks, but We Control the World

People who attend technical conferences like Design West are often mistakenly labeled as geeks. Do you even know what the real meaning of a geek is? Check out my video blog and I'll fill you in.

I'll also tell you about the some of the cool things I encountered at Design West, including a meet and greet with one of Hollywood's biggest stars.

Bad Parts Plague Oscilloscope

Bad Parts Plague Oscilloscope

As a newly hired engineer just out of college I was placed on the production line at Tektronix for two weeks to get familiar with production procedures and some of the product line. I was set to calibrating and testing type 547 storage oscilloscopes.

Everything went fine for several days until I ran across one unit that just wouldn't focus a proper spot on the screen. Since the cathode circuitry is sitting at -2000V, it was very difficult to measure anything with the scope power turned on. After getting bit a couple of times by the regulated high voltage, I decided to turn everything off and measure components one by one in the area where I thought the problem was.

I finally discovered a shorted 1N914 diode. Feeling confident, I got another fresh diode right out of stock. The instrument was built with silver-plated ceramic terminal strips, so I had to use special 2 percent silver bearing solder to fix it. I replaced the diode and turned the scope on.

There was no change in operation, so I again started looking for another component that was bad. After half a day of looking I kept coming back to the same diode that I had just replaced, but didn't test it because, well, I had just replaced it.

I finally decided it could be the only component that could cause this problem. Sure enough, it tested bad. I analyzed the circuit and could come up with no way that the diode could be damaged. It had to be bad right out of stock. I replaced it again and the scope worked and calibrated properly.

This entry was submitted by Jack Gilmore and edited by Rob Spiegel.

Jack Gilmore works for Advanced Energy, covering analog and digital design of industrial products using micro controllers including software and hardware design, circuit board layout, and product packaging. He has also designed RF instrumentation, RF matching networks, and a 333kW solar inverter and accessory products to enhance performance.

Tell us your experience in solving a knotty engineering problem. Send stories to Rob Spiegel for Sherlock Ohms.

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Researchers Design Hybrid Solar-Vibration Energy Harvester

Researchers Design Hybrid Solar-Vibration Energy Harvester

Researchers from South Korea have devised a nanotechnology-inspired hybrid device that can harvest energy from both sunlight and sound vibrations simultaneously, paving the way for the creation of cells that can potentially create a continuous and reliable energy source by leveraging the versatility of their energy sources.

A team of researchers including Dae-Yeong Lee from Sungkyunkwan University and the Samsung Advanced Institute of Technology created the device by integrating a piezoelectric nanogenerator and a silicon nanopillar solar cell to successfully harvest energy from two sources, "demonstrating its strong potential as a future ubiquitous energy harvester," they wrote in a paper.

Scientists have already come up with a number of ways for devices to harvest energy from the sun, wind, sound vibrations, and even ambient electricity that hovers in the air from device and appliance emissions. But the new hybrid device like the one described in the paper would be able to overcome some of the limitations of one-source energy harvesters, which depend upon their environment to work effectively, researchers said.

"Solar cells and nanogenerators require specific environmental conditions, such as solar light and mechanical vibration," Lee and his team wrote in the paper. "Thus, there is an increasing demand for a hybrid system that utilizes two or more energy sources in order to harvest ubiquitous energy continuously."

Researchers developed the device by integrating a silicon nanopillar cell -- the sunlight-harvesting part of the device -- with a piezoelectric nanogenerator. They fabricated the silicon nanopillar cell using a mask-free plasma etching process, and used a spin coating method to stack the piezoelectric nanogenerator atop the solar cell, according to the paper.

Researchers tested the device and found it could generate solar electricity with a 3.29 percent conversion efficiency while simultaneously generating 0.8 volts from the piezoelectric nanogenerator. The nanogenerator's output was based on exposure to a sound of 100 decibels. This type of result proved the device demonstrated "its strong potential as a future ubiquitous energy harvester," researchers said.

In addition to successfully harvesting energy from each of its components simultaneously, the device is also extremely compact, with a height of several hundred nanometers. This means it can fit in some of the smallest devices designed for ultra-low power that are beginning to leverage different types of harvesters rather than use batteries for power.

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