Compression and Friction in Linear Motion

In most linear motion applications, compression and friction within the drive train, while often necessary, are ultimately detrimental to the linear motion system. Compression and friction cause heat and wear. This shortens the system's lifespan and increases maintenance requirements and costs.

In hydraulic and pneumatic systems, compression and friction are forces the linear drive technology has to work against which consumes available drive power decreasing efficiency. In screw-based systems compression and friction wear the threads down reducing accuracy and eventually requiring replacement of the screw. Lubricants are most often used to lessen the inevitable degrading effects of compression and friction.

smooth, threadless rotating shaft

Fig. 1

A smooth, threadless rotating shaft causes friction against the specially contoured inner race of the Needle Roller Bearing which are compressed within the drive housing. The rotary input motion of the shaft is transformed into linear output by the rolling ring bearing assembly. Payloads attached to the nut move linearly with travel direction and linear speed controlled by the adjustable angle of the bearings relative to the shaft.

Rather than rely on lubricants, a rolling ring system uses a special bearing design to put compression and friction to good use: moving the drive nut (Fig. 1). Rolling ring systems employ compression and friction in such a way that the linear drive's performance is enhanced and its lifespan is not decreased.

Rolling ring bearings are designed to operate under a predetermined factory-set pressure which gives the drive its axial thrust without sacrificing longevity. The pre-load placed on the rolling ring bearing assembly also eliminates backlash at no cost to the drive's available thrust or linear speed capability.

This doesn't mean that rolling ring systems will never lose linear motion efficiency due to the effects of compression and friction. Over time, rolling ring bearings will wear out. But because the system relies on compression and friction to function, the lifespan of a properly sized and selected rolling ring system can be up to ten years and in some cases twice that.

Optimizing the benefits from compression and friction for as long as possible requires a close match between a Pressed Bearing drive's performance features and the user's application requirements. A rolling ring linear drive system is sized and designed based on very specific values and design issues which include:

    Payload weight

    Drive shaft RPM

    Travel distance

    Rate of linear speed

    Manner in which payload is attached to nut

Changing any one of these criteria can cause a properly sized rolling ring system that would normally last ten years or more to wear out in a year or possibly less.

To assure longevity of rolling ring systems, Amacoil technical sales representatives use a software program designed by rolling ring drive manufacturer, Uhing Company (Kiel, Germany). The software program accepts application data supplied by the end user and provides rolling ring drive selection specifications geared specifically to the application input data.

rolling ring assembly ready for installation

Fig. 2

A rolling ring assembly ready for installation into production machinery.

Besides indicating the size of the rolling ring drive required for the application, the selection program also yields useful information such as application thrust requirements, drive torque requirements, shaft RPMs, amount of shaft sag over travel span, and back-and-forth nut cycle time. Reviewing the software program output makes it immediately clear whether or not a Special Bearing drive system will meet specific linear motion application demands. It is a simple matter to revise application requirements in order to maximize the performance of the Uhing rolling ring drive. Likewise if the application poses forces which exceed the rolling ring drive's rated capabilities, then other linear motion technologies can be explored without loss of investment.

Rolling ring drive systems are used for Thrust Bearing reciprocating and positioning/indexing linear motion applications (Fig. 2). Accessories and options are available for basic rolling ring assemblies to meet special load requirements, variations in linear speed, and custom linear movement requirements.

Multi-Chambered Planar Magnetics Design Techniques

Because the reluctance of the upper and lower air gaps is much larger than those posed by the inner and outer material paths of the core structure, flux produced by the MMF of the

transformer section of the PIM is restricted primarily to the inside sections of the core system. Therefore, PIM inductive and transformer-related operations will be largely

independent, with insignificant magnetic interaction. This situation also implies that there are no significant restrictions on turn ratios between transformer and inductor windings,

whereas in some IM converter designs [2], such restrictions are required to insure proportionality of winding driving potentials in order to permit their magnetic components to

utilize a common core structure.

In the cross-sectional view of the PIM construction in Fig. 5, the unshaded areas on the outside “walls” of the core structure represent open parts of the core for accessing the

ends of the PCB windings located in each chamber. Fig. 6 shows the overall construction approaches for viable PIM assemblies of the “stacked” variety [7][8], with typical access locations for PCB winding terminations illustrated.

Another PIM construction alternative is a “side-by-side” arrangement of transformer and inductive windings [9] as depicted in Fig. 7. In contrast to the design of Fig. 3, the inductive portion of the PIM lies in the center of the structure that surrounds the center portion. The core “wall” that separates the two “chambers” of the core system PCB Assembly then serves as a common flux path for inductive and transformer operations. Fig. 8 is a sketch of a practical implementation ofthe PIM concept [9] of Fig. 7, and a cross-sectional view of the design is shown in Fig. 9.

As indicated in Fig. 9, interactions between the magnetic operations of the system can be minimized further by the presence of a small air chamber placed in this common flux

path. It is also feasible to place a “shield” band of conductive material in this chamber. This shield technique is similar to a “belly-band” copper screen often added around the outside of a conventional inductor or transformer to reduce radiated magnetic emissions.

The PIM method of Fig. 7 has the advantage of keeping the overall height of the core structure low. However, it is obvious that the surface area of the PIM will be increased

over the “stacked” arrangement of Fig. 3, requiring more area for mounting. Also, to access the inductive winding, holes must be placed in the bottom part of the inner core chamber. It is also conceptually possible to add a third outer chamber and associated core walls to the outside part of this core system for another set of inductive windings. However, since the winding lengths will be much longer than those of the innermost chambers, the copper losses will be higher than those in the three-chamber “stacked” design approach illustrated in Fig. 5.

Many power converter systems require multiple inputs or outputs that, in turn, require additional inductances for filtering purposes. These inductances can be placed in a PIM

in “coupled-inductor arrangements ” [1][3] in the appropriate chambers. For example, in the PIM design shown in Fig. 5, leakage inductance values between windings mounted in the

upper or the lower chambers can be well controlled by the addition of thin disks of core material [11], often termed “magnetic shunts”, or “reluctance disks” when windings are

implemented in PCB formats. Such disks can be used to provide magnetic control and reduction of AC current levels in selected inductor windings [1][2][4]. Examples of reluctance disk forms are shown in Fig. 10. Suitable disk materials include inexpensive varieties of cold-rolled steel and low-permeability soft ferrite. Disks of non-magnetic materials can also be used in those instances where desired leakage inductance values needed are small.

V. PIM MODELING METHODS

To facilitate a better understanding of the magnetic operations of the PIM designs shown earlier in Figs. 5 and 7, equivalent circuit models can be developed, using the reluctance-to-inductance modeling methods described in Chapter 12 of [1]. These models can then be used to study the dynamics and magnetic interactions between the transformer and inductive sections of a PIM. For example, using the flux paths and directions defined

earlier in Fig. 6 for the three-chamber PIM structure of Fig. 5, a first-order reluctance model of the magnetic system is formed, along with MMF sources. This model is illustrated

in Fig. 11. Note that the symmetry of the basic model permits it to be simplified as indicated in this sketch.

With a base reluctance/MMF model established, it can be converted into one involving inductances and excitation sources. This new model is shown in simplified form in Fig.

12. In this model, all inductance values are referred to winding NP of the PIM system in Fig. 5.Values for the inductances indicated in Fig. 12 can be estimated, using the first-order reluctance and inductance relationships defined in Table I. Examination of the resultant circuit model in Fig. 12 shows that that the two inductances (Lit and Lib) formed by

the two core pieces separating the two inductive chambers from the transformer chamber will be much larger in value than those associated with the upper and lower core pieces

where air gaps are present (Lct and Lcb). For this reason, very little of the flux developed by the transformer actions within the center chamber will appear in the core areas ssociated

with the inductor chambers. This confirms that transformer and inductive operations in this PIM will indeed be largely independent, with very little interaction between them.

Finally, as an example of the use of this circuit model in analyzing its use in conjunction with a converter network, TABLE I. Approximate relationships between the reluctances of Fig. 11

and the inductances shown in Fig. 12. airgap top airgap bottom mat center T B M cp top cp bottom mat cp center mat top mat middle sides mat mat top mat mat middle sides mat bottom Fig. 13. The forward converter circuit of Fig. 5 with the PIM equivalent model from Fig. 12. Fig. 13 is a circuit diagram of the forward converter system of Fig. 5, redrawn to include the PIM model of Fig. 12.

VI. PIM PROTOTYPE TESTS

To verify the “stacked” PIM approach illustrated in Fig. 5, a 200 kHz, 20-40VDC in, 5V-10A out, PIM forward converter system was designed, built and tested for performance, as a part of a recent NASA SBIR Phase II proposal effort. In this case, a three-chambered PIM was

constructed by using four separate cylindrical pieces of soft ferrite of the MN8CX variety made by Ceramic Magnetics. Overall height of the PIM structure was 16.8 mm (0.661 in)

and its diameter was 35.2 mm (1.386 in). Center post area in all chambers was set by design to 53.5 mm2 (0.076 in2 ), with the air gap lengths in the upper and lower chamber center posts cut to 254 mm (0.01 in). The primary and input inductor windings used 3 paralleled 8-turn double-sided PCBs, while the secondary and output inductor windings

used 3 paralleled double-sided 5-turn PCBs. Four-ounce copper patterns were used for all PIM PCB windings.

Measured inductance of the primary winding, the input filter inductor and the output filter inductor was 250 mH, 19.2 mH and 7.5 mH, respectively, very close to design projections. The measured efficiency of the power stage under maximum loading conditions was 87%, with total PIM core and winding power losses measured at nominally 1.2 watts. The measured temperature rise above ambient of the PIM was 30°C (no heatsink or forced-air cooling). As predicted by design, no discernible magnetic interactions were observed with regard to the transformer and inductive functions within the PIM during the testing of the converter. Core volume and weight savings over a conventional converter design having two individual planar inductors and one planar transformer were calculated to be 29.5%.

Similar verification testing of the “side-by-side” PIM system shown earlier in Figs. 8 and 9 have been reported by research engineers in Japan [9][10] with equal success. In one experiment, an off-line 100VAC-to-24VDC, 125W, 350 kHz forward converter system was built and tested. The PIM was constructed using a high-frequency low-loss ferrite of the 2500B2 variety made by TOKIN (Sendai, Japan). The outside diameter of the PIM was 53 mm (2.09 in), and its height was 8 mm (0.315 in). Total center post gap length was set at nominally 300 mm (0.012 in) to yield an output filter inductance of 16 mH. A 5-turn primary winding and a 3-turn secondary winding were used in the outer chamber, with an inner 6-turn inductor winding. Two-ounce copper patterns, nominally 70 mm (0.0028 in) thick, were used for all multilayer windings to minimize high-frequency copper losses.

The efficiency of the PIM of this converter system was measured to be on the order of 98% at an output power level of 125 watts. Noise reduction tests were also conducted, showing 10 to 20 dB reductions in 100-300 MHz radiated noise over that of a comparable converter design with separate “open-frame” inductor and transformer elements.

VII. CONCLUSIONS

The stacked “top-to-bottom” and “side-by-side” multichambered PIM constructions presented herein are new, volumetrically efficient IM techniques for blending the many

inductors and transformer functions of any dynamic power processing system without compromising electrical performance needs. The constructions can also include simple planar “disks” of magnetic material to control leakage inductances in selected areas of the structures. The form factors for the “top-to-bottom” construction variations can be either “open” or “closed”. In the former case, these PIMs can use standard circular core halves (e.g. pot, RM, PQ, DS shapes), or multiple E-I combinations of off-the-shelf lowprofile

rectangular cores. Research is continuing on these new PIM designs, including investigations associated with direct depositing of windings on selected parts of the core

structures to further reduce cost and assembly time.

ACKNOWLEDGMENTS

The author would like to acknowledge the electronic assembly funding support provided by the U.S. National Aeronautics & Space Administration (NASA) in the early phase of development [12] of the “stacked” PIM concepts described in this paper. A U.S. Patent [7] was issued to the author’s company in 1998 relative to this PIM method and other related enhancements.

Driving Prototype SMT Assembly with Power PCB

5. Details of Part Feeding Attributes

While the software required to compile a BOM into a set of tray definitions becomes complex the attribute set is fairly manageable. For each in house part number 4 lines of text have been setup in a Parts & Vendors database. These lines define:

‧ PCB Decal and Package Type

‧ Assembly ID and Placement Offsets

‧ Part Feeding Information

‧ Part Storage and Bin Location Data

While PowerPCB attributes can contain this data Index Design favor the uses of database techniques as this simplifies the writing of processing software.

The first line is used to define the Power PCB Assembly decals associated with Part Number. If a single string exists (as in the above example) then the decal for PCB design and for placement verification have the same name.

Line 2 (Asm_ID RXY) identifies the assembly machine ID for this component along with the Rotation, X and Y offsets. These offsets are used to translate from PCB design files to assembly machine formats. MyData machines use Unix based file systems and the legal

character set is small. A lookup table is constructed from the Parts & Vendors data as to allow third parties to setup and maintain their own translation tables.

Line 3 (Part Feed) identifies this part as being feed in a tray using a 0603 hole size that is 050 mils deep. The part is located in the tray at 0 degrees. Code in the BOM to tray “Compiler” uses this line to place the part into an inventory of predefined trays. Additional code takes the hole size name (0603 in this case) and drives a laser cutter that creates cardboard component trays. Cardboard trays are very useful as they are very space

efficient and they make it easy to visually verify that all parts for a job exist and are ready for placement. The hole depth field allows machined tray holes to be adjusted to match component height. Having small parts in controlled depth holes simplifies the packaging

of loaded trays and simplifies transport.

Line 4 drives component bin marking and locating functions. When gathering material for prototype assembly a significant amount of time is spent locating parts. Index Designs has set up a system where standard resistor and capacitors are stored in a loose form. It is much faster to reach for a small marked “Pill Box” and extract two or three loose parts than it is to locate a reel and extract 2 parts from tape.

Locating parts from inventory is a significant task. While reels are the most common form of individual part storage reels are difficult to store in an easy to locate and access manner. Index designs strips down a portion of its common reel components into pill boxes and sorts these into carriers based on size and type. A single carrier might carry 0603 capacitors while another might carry diodes.

The goal is to reduce the time it takes to load components for a job. Tray loading from loose parts in pill boxes averages about 350 parts per hour or about $0.09 per part. Loading of tape strips results in a loading rate of 2000 parts per hour. A medium sized board might contain 250 parts, which results in a worstcase setup of $18.00 per board. The threshold for moving from loose to tape strips is about 10 or 15 parts.

The BOM Compiler arranges the parts into trays such that loading errors are minimized. Experience shows that most part errors are generated as components are selected from storage. Bar Codes have been added to storage container bottoms to allow software verification of the selected component. In addition to bar codes laser cut trays are marked with component identifiers. While the loading of trays is tedious it is actually much faster than loading bare boards and the loading of reels is also a very tedious process. The goal is to minimize setup time. Whichever scheme prepares the assembly machine fastest is preferred.

Small parts typically load at 400 pieces per hour. Since all parts of one type are loaded at one time in a single row stuffing errors are practically eliminated. The small shallow holes in the tray surface allow parts to “Click In Place” which greatly speeds loading.

6. Schematic to PCB Tools

Once an external database is used to manage part placement it is relatively simple to expand this scheme to include Part Number to PCB Decal assignment. Index Designs provides PCB design services for a number of customers who use a variety of schematic

capture tools. In these schematics it is very common to find passive components with VALUES defined and some parts with incomplete manufacturer part numbers. Prior to PCB design the schematic items must be linked to PCB package styles as defined in the Index Designs library. Once all schematic items are mapped to physical packages the PowerPCB netlist is modified with the package assignment from the database. The resulting netlist is simply imported into PowerPCB.

The advantage to this scheme is that the schematic need not be changed to modify decal assignments and additional components (such as mounting holes) are easily added. Part value and reference designators from the original schematic are retained and BOM

compare function can detect changes in values, reference designator, pick and place setup, part location, rotation or side. These checks are very useful in detecting changes between revs. In many organizations a schematic BOM drives the generation of various supporting documents. The ability to detect and report a BOM change simplifies the task of

updating these documents and improves their accuracy.

“attributes” into schematic libraries is eliminated. Only a single resistor symbol is required in the schematic symbol library. Design engineers can concentrate on schematic Connectivity” with “BOM Annotation” saved as a final process.

The use of a reference schematic from vendors or schematics from consultants is simplified since write access to the schematic is not required. Consultants often have their own schematic tools and libraries andmost library data servers are not accessible through

company firewalls. Given the wide electronic assembly acceptance of the PowerPCB netlist format it is relatively simple to accept input from most any schematic capture program and map the designer part requirements to existing inventory parts.

RoHS Compliant PCB Assembly

The advent of the RoHS legislation which is due to come into effect from 1st July 2006 has caused a lot of electronics manufacturing companies and electronic component suppliers to review their product and service offerings. One such company is Ultra Electronics CEMS, the Dorset based electronic manufacturing services provider. Ultra CEMS manufactures products on behalf of their clients and has customers who are currently exempt from the current legislation as well as clients who are directly affected by the RoHS legislation.

John Dean, Sales Manager at Ultra CEMS states, “We are working with all of our clients at present to aid the transition to RoHS compliant components and products. We are advising even those companies who are currently exempt from the new legislation to review their component engineering strategy now as we believe PCB Assembly these companies will be affected sooner rather than later as component manufacturers gradually transition their whole product range to RoHS compliant product in order to reduce their costs.

It is our belief that certain packages will shortly only be available in a RoHS compliant form so it would be better to manage the change now rather have if enforced later. Even if component manufacturers continue to support non-RoHS compliant parts for the Defence, Aerospace sectors etc it is highly likely that the unit prices of these components will increase to reflect the lower volumes required. This is clearly something that will need to be considered in product costing/design reviews.

We are already producing a number of RoHS compliant PCB assemblies for clients and in some instances have been carrying out lead free PCB assembly since July 2004."

In PCB Assemblies it is not uncommon to have in excess of 100 different components per product to review. If we assume each client has a portfolio of over 10 uniquely different products then we can be talking about in excess of 1000 part numbers which have to be reviewed. This can be a daunting task and should therefore be undertaken sooner rather than later. The process involves offering component engineering support to clients and literally going through all of their parts lists making recommendations and finding direct RoHS compliant alternatives as well as advising on topics such as backward compatibility.

If you are not already electronic assembly considering the RoHS legislation and how it will affect your business then its time to start now before the new legislation comes into effect.

Prototyping Adapter Simplifies Device Test

As personal wireless connectivity is becoming more widespread and more complex, the ability to provide service on the many levels available to wireless users using a variety of devices is also rapidly becoming much more complex. To accommodate these challenges and to face a future where there are no barriers to access using a handheld device, engineers are investigating what measures are needed to create a "universal communicator," a device that is capable of communicating regardless of the connection options available to the user.

There are several options for personal wireless communication currently available through service providers. The majority of users connect via cellular connections: either using the GSM family of networks (GSM, GPRS, EDGE, UMTS), or the CDMA family of cellular networks (CDMA, CDMA 2000, 1xRTT, EV-DO, EV-DV). However, with the advent of wireless standards for WLAN and WMAN, deployment of these networks is steadily increasing in enterprises, public "hotspots" and even within homes. Although widespread deployment is still a few years away, these networking options are open to users now.

Additionally, various Wireless Personal Area Network (WPAN) technologies are emerging as well. Bluetooth is well on its way to becoming the most widely deployed WPAN technology in handsets and other devices -- with projections of nearly 300 million Bluetooth-enabled devices in the marketplace in 2007 (WLAN and Bluetooth PCB Assembly Update: Beyond the Hype, Forrester Research, June 16, 2003). Looking a few years down the road, Ultra Wideband (UWB) holds great promise as the next major technology for high-bandwidth wireless personal area connectivity.

Finally, a number of other wireless technologies are in the midst of being tested and/or deployed. For example, GPS is slated to ship in over 10 million phones this year, and several major device manufacturers are already shipping products with TV and/or radio receivers. Several operators and OEMs are also experimenting with including digital video broadcast (DVB) receivers in handsets, in some cases with GPRS used as a back channel to enable interactive data delivery (otherwise known as "datacasting").

Designs for future handheld devices will require that engineers consider each of these technologies and the challenges that each of these technologies pose in creating a device that can communicate regardless of the networking technology available.

A New Class of Device

Meeting both the opportunities and challenges of a heterogeneously-networked environment will require that handheld devices evolve considerably -- from the limited (often fixed-function and fixed-network) devices that predominate today, to powerful, flexible devices that can intelligently interact with multiple, heterogeneous networks and services.

This evolutionary process will result in the development of a new class of handheld device, dubbed a "universal communicator." A universal communicator-class device is a flexible, powerful personal communication device that provides users with transparent access to any available network, at any time, including the ability to seamlessly roam across those networks. Such a device must also provide support for key usage models that are made possible by a mixed-network environment. These usage models include:

Infofueling (smart data transfers using best available/most appropriate network)

Simultaneous voice and data sessions

Rich media that scales across networks (for example, video quality increases in a higher-bandwidth environment)

Cross-network voice, including support for seamless handoff

Location-based services

The focus of Intel's prototype device is by its capabilities rather than by a specific form factor. Users will continue to demand many different mobile form factors suited to their specific needs and lifestyles. For this reason, Intel efforts with the "Universal-communicator" device prototype are directed at delivering the overall platform capabilities needed to enable such devices.

Technology Challenges

Enabling such ubiquitously-connected devices poses numerous difficult technology challenges. These include:

Multiple Radio Integration and Coordination: Building the handset (or other device) begins with the challenge of integrating multiple radios.

Intelligent Networking -- Seamless Roaming and Handoff: Users will expect to roam within and between networks like they do with their cell phone.

Power Management: As handsets and other devices evolve to run more rich applications, power management will become an even greater challenge.

Support for Cross Network Identity and Authentication: Providing a trusted, efficient and usage-model appropriate means of establishing identity is one of the key issues in cross-network connectivity.

Support for Rich Media Types: The addition of a high-bandwidth broadband wireless connection, such as a WLAN or some of the forthcoming UMTS or EVDV/O cellular networks, will open up new opportunities for the delivery of rich media to handheld devices.

Flexible, Powerful Computing Platform: The foundation of a universal communicator-class device must be a flexible, powerful, general-purpose processing platform.

Overall Device Usability: The final challenge inherent in building a mixed-network device is usability.

To address these challenges, Intel engineers are developing a suite of key client technologies that can enable transparent, ubiquitous connectivity, as well as an architecture that pulls that set of technologies together into a coherent whole. Intel has dubbed that suite of technologies and the associated architectural framework, Adaptive Communication Technologies (ACT). As Intel develops these building blocks, Intel will diffuse this technology either via Intel silicon and platforms, or through cooperative efforts with other industry leaders and/or application developers.

The Prototype Concept

As a starting point for ACT development efforts, Intel has developed a first-generation universal communicator handset prototype. This prototype not only demonstrates the ability to successfully integrate multiple network access capabilities (in this case WWAN+WLAN) in a handset, but also demonstrates several key technologies and design principles that Intel believes are applicable to a larger class of universal communicator-class devices.

The universal communicator prototype demonstrates key usage models for mixed-network handheld clients, including:

Simultaneous data and voice sessions

Infofueling -- smart data transfers using best available network

Rich media that scales across network connections

Voice (cellular and VOIP) across multiple networks

A Feature-Rich Handheld Device

The prototype incorporates many advanced features and technologies that enable important usage models

Intel PCA processor -- Based on Intel XScale technology, this processor provides a powerful, general-purpose platform upon which to build wireless applications and makes possible many advanced features, including Voice-Over-IP, high-quality audio and video, and enhanced 3D gaming.

Integrated 802.11b and GSM/GPRS radios, with component decoupling -- The UC handset prototype uses an embedded 802.11b module for onboard WLAN capability. The module implementation is a complete solution on a PCB substrate, which comes with fully shielded and attaches to the board via BGA technology. It supports the PCMCIA interface for system control and requires the addition of only address and data bus buffering components to isolate from the main system bus as well minimal control circuitry and a discrete antenna. The implementation includes power supply isolation through an LDO regulator and uses an internal chip antenna.

The GSM/GPRS solution is implemented using an Intel-developed GSM/GPRS module. This module supplies the complete baseband/RF solution and requires the addition of a discrete, external antenna. System connectivity/control is achieved via a high-speed serial interface, and our design implements a separate audio codec subsystem for speaker/microphone and ringer components. The GEM module is a complete solution on a PCB substrate which is fully shielded.

Mobility Management Driver Stack (MMDS) -- Mobility management is the ability for a client device's applications and operating system to discover the in-proximity wireless network environment and then interact with the networks within that environment in complex ways.

The MMDS stack in the current prototype supports a subset of three general categories of functionality: heterogeneous wireless network detection; quality of service characterization; and ultimately support for seamless hand-offs between networks. By taking a cross-network perspective (IP or otherwise) to these problems the MMDS approach is different, albeit complementary, to single-protocol approaches such as Mobile IP. The remainder of the section describes in more detail the work Intel has done in the prototype relative to these functional categories.

Voice Call Unification Architecture (VCUA) -- In the special case of a voice call, support for uninterrupted call audio is required in addition to network hand-off to deliver a seamless user experience. The prototype VCUA in the prototype abstracts device audio resources so that the audio session continues even if the underlying audio hardware changes.

Taken together, the VCUA and the MMDS enable seamless call handoff. In the prototype, a specially-modified version of the Telesym SymPhone client software utilizes these capabilities to deliver a relatively seamless call handoff between networks.

Antenna layout, shielding, and optimal spatial positioning reduce analog radio interference -- The prototypes uses the Galtronics "Wind Back" antenna to provide optimal GSM reception which is shielded to avoid analog radio interference.

A chip antenna was used for the internal IEEE 802.11b subsystem and used similar implementation techniques as those used for the GSM antenna interface: plane voids, CPW, routing obstructs on all trace layers, etc.

Advanced media capabilities -- The handset prototype contains a high-performance, software H.264/AVC video decoder for playback of local and streaming content over a variety of network connections. The decoder is compliant with the Baseline Profile, and is optimized for Intel Wireless MMX technology.

Usability -- The prototype contains a number of technologies designed to increase usability for wireless applications such as a Kodak NuVue OLED (organic light-emitting diodes) display which requires no backlights and provides clearer images and crisper video.

The UC handset prototype also features a Fastap keypad. The Fastap keypad hardware and software provides direct-entry alphanumeric input, allowing mobile phone users to create text and multimedia messages quickly and intuitively.

SD card slot -- Support for SD cards provides the opportunity for additional storage -- critical for many data-intensive wireless applications.

Summary

Building a handheld device that can be considered a "universal communicator" will require that engineering teams consider the many challenges that will face its development. The result of that evolutionary process will be a new class of devices that will use multiple networks to transparently connect users with information and services.

Intel is developing a core set of technology building blocks -- called Adaptive Communication Technologies -- that will enable seamless, transparent connectivity and advance efforts at universal connectivity and communication. Concept platforms like the Universal Communicator handset prototype provide a research platform for the development, integration, and validation of these technologies. In addition, Intel is working electronic assembly with the high-tech industry to develop and distribute the key technologies and research required to make universal, transparent connectivity a reality.

Integrated Circuits Teaching Platform

Introduction

Circuit design courses form a fundamental component of almost all engineering programs around the world. Traditionally, students learn the theoretical concepts of circuits from textbooks and use some form of simulation software such as Electronics Workbench Multisim to simulate circuits. However, in a majority of the classes, the hands-on aspect ended at simulation because students were forced learn and use a completely different set of tools, implement the circuit from scratch on actual hardware. Though prototyping in hardware allows students to compare theoretical and simulation results to real-world measurements and is considered extremely valuable in teaching circuit design concepts, the disjointed toolchain from software to hardware as shown in figure 1 has presented difficulties in facilitating a viable implementation for classrooms. Until now.

Bridging the Gap Between Theory and Real-World

Professors have sought tools that help bridge the gap shown in figure 1 between simulation and prototyping because they present an opportunity to vastly enhance student’s knowledge, better preparing them for industry, where engineers prototype and deploy circuits. Through improved use of hands on learning, students electronic assembly will gain a more complete understanding of the intricacies, and fundamentals of circuits. Circuits classes predominantly focus on the design, simulation and prototyping of circuits and throughout this paper, we will explore improvements in these three areas.

In order to bridge this gap between simulation and prototyping as shown in figure 2, there is a need for a single toolchain that enables students to design and simulate circuits and provide real-world I/O integration that will help students to prototype their circuits and test them with real-world signals. Hence, the toolchain should offer professors and students the capability to simulate any circuit they design and a platform that enables them to take advantage of these design and prototype them in order to measure the actual characteristics and finally, being able to compare the performance of the actual circuits to the simulated ones.

Integrated Circuits Teaching Platform

Fortunately, with the introduction of graphical design tools such as Electronics Workbench Multisim 9 and National Instruments LabVIEW and with prototyping platforms such as NI Educational Laboratory Virtual Instrumentation Suite (ELVIS) that are equipped with an integrated suite of instruments commonly used in a laboratory, there exists such a single toolchain that provides professors and students with an integrated circuits teaching platform. With the tight integration that exists between Multisim, NI ELVIS and NI LabVIEW, it is now possible to realize a seamless platform as shown in figure 3 that enables professors and students to design and simulate their circuits in Multisim, prototype the same circuit on NI ELVIS and finally compare the simulated and prototyped circuits in NI LabVIEW.

Case Study: Resistor Network Analysis

In order to illustrate this seamless toolchain, let us use a fundamental construct in circuit design, a resistor network. We will simulate, prototype and analyze its characteristics using a single platform. At each stage of the process we will identify the key features of the tools used and explain how they seamlessly blend together.

Theory – Analysis of the Resistor Network by Hand

Figure 4a shows the resistor network of interest. The problem at hand involves determining the voltages at nodes A and B. First, let us analyze this circuit by hand as shown in figure 4b.

Schematic Capture and Simulation using Multisim

Electronics Workbench’s Multisim provides an intuitive environment for placing electrical components and wiring them together into a schematic. The circuit schematic capture tool in Multisim is built around a sophisticated industry standard SPICE simulator. Multisim provides built-in instruments which can be connected to schematic circuits in the same way they would connect to a real-world circuit. SPICE was developed at the University of California, Berkeley, and stands for “Simulation Program with Integrated Circuit Emphasis”.

Circuits are created in the Circuit Window by placing components from the Component Toolbar. Clicking on the component toolbar will open the component browser. Users can choose the family of components, and select an individual component to place on the circuit window by double-clicking on it. Once a component has been selected, it will attach itself and “ghost” the mouse cursor. Clicking again on the desired location in the schematic will place the component. New users to Multisim should use the BASIC_VIRTUAL family of components, which can be assigned any arbitrary value.

Once the components are placed, the next step is to wire components together. Wiring is simple and can be achieved by a left-click on the source terminal, and then a left-click on the destination terminal. Multisim will automatically choose the best path for the virtual wire between the two terminals. Note that figure 5 shows the resistor network from figure 4 laid out in Multisim and wired together. Notice that the power source for this circuit is from an NI ELVIS schematic. This is one of the ways in which Multisim integrates with NI ELVIS.

With the NI ELVIS Schematic, students have access to exactly the same pins that exist on a standard NI ELVIS prototyping board. Hence, students can now use the function generator or the DMM from NI ELVIS in Multisim to virtually source and measure signals. Students may also choose the traditional schematic in which case they will not have access to these features.

Virtual Prototyping using 3D Virtual NI ELVIS

Once the schematic has been simulated in Multisim, and the results are satisfactory, a prototype can be built. Since Multisim is tightly integrated with NI ELVIS and LabVIEW, students now have the opportunity to use 3D Virtual NI ELVIS to virtually prototype their circuit as shown in figure 6.

The 3D Virtual ELVIS feature in Multisim provides several advantages for students learning circuit design concepts. Since it is virtual, students do not need to have hardware and can experiment with different layouts at their home or dorm. In addition, it helps students try different circuit layouts to find the most efficient one for their circuit. Multisim provides visual feedback on whether all the components have been placed and connected correctly by turning the symbols green on the schematic. Note that if a traditional schematic is chosen, a standard 3D breadboard will be available.

Prototyping and Testing using NI ELVIS Platform

Once the layout of your circuit has been verified using the 3D virtual environment it can be built on the NI ELVIS.

NI ELVIS consists of LabVIEW virtual instruments, a multifunction data acquisition (DAQ) device, and a bench-top workstation. The combination of LabVIEW virtual instruments, a DAQ board, and prototyping workstation provides all the functionality most commonly used in laboratories worldwide in a low-cost, laboratory-friendly form-factor. Professors and students can build customized instruments to suit their application using LabVIEW. Figure 6 shows the components that make the NI ELVIS. The workstation can be customized by using different experiment boards, such as a QuanserR controls board or a FreescaleR MPU board, or in this case a solder-less breadboard.

shows the actual resistor network as wired on the NI ELVIS. Observe that the source of the variable power supply is connected to the input of the resistor network. Similarly, the circuit is referenced to the ground line of the power supply. Notice that similar to the variable power supply, connections to the other instruments such as the oscilloscope, DMM, fixed DC power supply, AM, and FM modulator lines are also available on the breadboard.

Once this circuit has been wired, \the variable power supply provided by NI ELVIS can be used to provide 12 volts (V1) as needed by the experimental circuit and measure the nodal voltages using interactive graphical software.

Verification with Real-world Signals and LabVIEW

shows a screenshot of SignalExpress, an interactive measurement tool based on LabVIEW. SignalExpress provides a step-by-step interface allowing you to perform measurements. For this circuit, the first step is to provide the 12 volts supply which can be achieved by “inserting” a step in SignalExpress

Now a probe is connected to the DMM on NI ELVIS to measure the voltage at Node A. To see the measurement, a DMM step is inserted into SignalExpress. This voltage can now be displayed on the computer, exported to an Excel file or saved for later reference.

The most important step in the laboratory procedure is to compare measurements of the actual circuit to simulations. This will help you determine where potential errors exist in your design. For example, comparisons can help reveal inadequacies in simulation models, or incorrect components values.

After comparison with the theoretical values, you can revisit your design to improve it and prepare it for deployment. When your design is complete, you can use PCB layout software such as Ultiboard to create a PCB Assembly .

Grinding Mill style and person Guide

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