Navigation is an innovative technology that adds a new dimension to orthopaedic surgery

Strapdown Inertial Navigation Technology

On the 21st February 1997, I attended a Colloquium on Airborne Navigation Systems organised by the IEE Aerospace Group in association with IEE Professional Group E15 (Radar, Sonar, and Navigation Systems) and the Royal Aeronautical Society at the IEE, Savoy Place, London. One of the six lectures was on Inertial Navigation Systems (INS), and this book was one of those strongly recommended by the speaker.

Inertial navigation systems were first developed in the early 1950s by the Sperry Gyroscope Corp. They involved the combination of accurate mechanical gyroscopes and sensitive accelerometers to carry out navigation by `dead reckoning'. The early stimulus had been the requirement to develop air navigation systems which were independent of ground beacons, which might suffer jamming or destruction in time of war, or fading or atmospheric problems in peacetime. Obviously, INS find their principal application in the guidance of airborne, marine and land vehicles. More recently, however, other applications have been developed, such as surveying underground-pipelines and bore-holes during drilling operations. The two authors have extensive backgrounds in these diverse fields, David Titterton in aerospace with the Defence Research Agency (DRA), and John Weston in well-bore surveying with SperrySun (UK) Ltd.

The book has 13 chapters in all. The first three deal with a basic introduction to, and the fundamental principles of, INS along with their historical development, and the basic principles of strapdown INS. They describe how the original INS used a stable platform to carry the inertial sensors and this platform was mechanically isolated from the motion of the host vehicle, whereas, in the later Strapdown INS, the sensors are rigidly strapped down (i.e. rigidly attached) to the body of the host vehicle. This results in size and weight reductions, lower cost, and greater reliability. The quid pro quo (downside) is the requirement for greater computer complexity and improved sensors. Although there are earlier books which dealt with the well-established `platform technology', this latest book focuses particularly on the later `strapdown technology'.

Chapters 4 and 5 cover gyroscopes, from the earlier mechanical gyroscopes via a whole host of rate (such as mercury or magneto-hydrodynamic), vibratory (such as wire, disc, tuning fork, quartz, or silicon), and cryogenic types (such as nuclear magnetic resonant or superconducting) to the later optical types (such as ring laser or fibre optic). Their principles of construction, operation, performance characteristics, and errors are all considered in much detail.

Chapter 6 covers the numerous approaches to the construction of the accelerometers required, in a similar way to the previous two chapters - both mechanical and solid-state devices being considered. Much consideration is also given to multi-sensors which can sense both acceleration and angular motion simultaneously.

Chapter 7 deals with testing, calibration, and error compensation, with specific reference to qualification, acceptance, and reliability tests. Many test procedures are described and there are numerous photographs and diagrams showing test rigs and equipment, along with requirement characteristics.

The second half of the book (approximately) is devoted to strapdown INS technology. Chapters 8 to II delve into considerable detail of the components, electronics, compensation, alignment, computers and computation, error correction, algorithms, and performance analysis of Strapdown INS. A considerable amount of necessarily complicated mathematics is presented to support the technology and aid the design, analysis, and understanding of the systems.

Chapter 12 considers integrated navigation systems where the INS is used in conjunction with other navigation aids (such as the well known VOR/DME and TACAN; hyperbolic systems such as: Decca, LORAN-C, and Omega; and the Global Positioning System - GPS) in order to improve accuracy and reduce costs.

The final chapter applies the various aspects of INS considered previously to a design example. Various factors and requirements are considered and discussed for the guidance of a surface-launched tactical missile. The system design and analysis, errors and compensation, alignment, and computational requirements are all considered in some detail.

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Surgical Navigation Technology: A New Chapter in Orthopaedic Surgery

Columbia St. Mary’s is one of the first health care systems in Wisconsin to use surgical navigation – or computer-assisted joint replacement technology – for orthopaedic surgery.

Surgical navigation, which began at Columbia St. Mary’s in September, 2003, is an innovative technology that adds a new dimension to orthopaedic surgery. The first 10 cases were performed in September by orthopaedic surgeons Michael Anderson, M.D., and James Stiehl, M.D.

Surgical navigation involves the use of a computer and sensors placed over a patient’s bones. The sensors allow surgeons to “see” a patient’s joint during the surgery and more accurately determine the best placement of knee or hip implants. “Surgical navigation uses three-dimensional computer guidance during surgery to help the surgeon align joint replacement implants better,” said Dr. Anderson.

Dr. Smith compared surgical navigation to the global positioning satellite (GPS) systems that help pilots and drivers navigate. “It is like having a GPS in the operating room, but instead of moving off of a satellite, you move off of cameras right in the operating room,” he said.

Surgical navigation will be especially important for difficult joint replacement cases, Dr. Anderson explained. Cases in which patients have an abnormal bone structure or previous surgeries make it difficult for doctors to perfectly align the new joints in surgeries because the normal markers are not there. “It helps take the guesswork out of surgery,” Dr. Anderson said.

The new technology will increase the success rate of implants, and it will allow patients to enjoy the longest possible wear of their implants, Dr. Stiehl said. “Computer-assisted surgical navigation marks a new chapter in patient care,” he added.

Surgical navigation also will allow for more minimally invasive surgeries. “You can use much smaller instruments and make shorter incisions,” Dr. Smith said. “You don’t necessarily have to see where the joint will be placed because the computer has the reference points. This should allow for less invasive surgery and provide a more consistent surgical result.”

Dr. Smith said that this technology has been used in Europe. Only about a dozen places nationwide are using surgical navigation, and it is mostly found in academic settings where testing of the software is being practiced.

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Etronica announces release of a navigation technology for the interactive television industry

Etronica Corporation today announced the release of its Custom Metatagging and Brilliant Query System™ tailored for the interactive television industry. The Etronica technology is designed to enhance the end-user's TV viewing experience. The robust, simple-to-use software toolset enables cable and satellite content distributors to expand the capabilities and value of their on-screen program guides.

A key feature in this release is a proprietary keyword set, or "dictionary," tailored specifically for use with electronic program guides.

Etronica's multi-dimensional search capabilities provide easy access to thousands of titles and descriptions of TV programs, giving viewers a richer entertainment experience. A fan of "The West Wing," for example, can use Etronica's intuitive point-and-click on-screen interface to quickly find other upcoming shows about the White House, or starring Martin Sheen, or that have some other attribute of particular interest to this viewer.

Etronica is intended to maximize the value and customer appeal of the interactive programming service, and to offer system operators a competitive advantage over services that provide only traditional "scroll-and-wait" program listings.

A unique feature of the Etronica technology is its ability to "learn" the program preferences of the viewer who uses it. The software uses adaptive technology to deliver a smarter-search capability so that the more the viewer uses the Entronica-enhanced guide, the more likely the guide is to display first the programs of greatest interest to that viewer.

The Etronica software also includes analytical tools which enable content providers to quickly and accurately identify the programming attributes that are of greatest interest their viewers, and that result in viewers selecting premium content. This analysis of programming preferences is done while fully protecting subscriber's privacy.

The software is now available for licensing to hardware manufacturers and middleware developers of digital settop boxes for television programming, personal video recording, and video-on-demand applications. It is designed to run on all current set-top-box platforms.

Etronica CEO Jim Saake explains, "We have leveraged our experience in advanced search and navigation technology by applying it to solve a critical problem in today's iTV industry. There is so much programming for consumers to choose from, how can they quickly and easily find exactly what they want? With Etronica, the wealth of programming choices available via interactive TV becomes a valued benefit. Without it, consumers can become frustrated by what they see as an overwhelming deluge of options. Etronica helps content providers attract and retain subscribers."

At the recent Consumer Electronics Show in Las Vegas, Mr. Saake met with a number of members of the industry who expressed strong demand for enhanced electronic programming guides. Etronica's announcement of its new release comes at a time that the industry is seeking a way to allow consumers to efficiently navigate and manage the wealth of programming content available today via technologies that overcome the limitations of the traditional two-dimensional grid. Mr. Saake said he was "extremely pleased with the very strong expressions of interest in Etronica technology we received at the CES event" from members of the interactive TV industry.

In addition to providing its software solutions, Etronica also provides consulting services for the integration of its technology into existing hardware and software infrastructure.

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Carnegie Mellon on team chosen to develop autonomous navigation technology

Carnegie Mellon University's National Robotics Engineering Consortium (NREC), part of the Robotics Institute in the School of Computer Science, has been selected to be part of a team formed by General Dynamics Robotics Systems (GDRS) to negotiate toward a contract to develop an Autonomous Navigation System (ANS) for unmanned and manned ground vehicles.
The choice of GDRS, a wholly owned subsidiary of General Dynamics Land Systems, was announced by the Army's Future Combat System integrator team, which includes The Boeing Co. and Science Applications International Corp. (SAIC).

In the Future Combat Systems ANS program, the GDRS team will design, develop, integrate, test and manufacture a system capable of autonomously controlling any of several vehicles designated by the Army, including the Multi-functional Utility Logistics Equipment (MULE) platform, the Armed Reconnaissance Vehicle (ARV) and Manned Ground Vehicles. The ANS program will provide navigational, perception, path-planning and vehicle-following algorithms, as well as the requisite on-board sensor package for autonomous mobility.

The National Robotics Engineering Consortium will be a major subcontractor to GDRS and will lead the development of perception and path planning within the Autonomous Navigation System. "We are excited about this opportunity to transition over a decade's worth of unmanned ground vehicle autonomy research to support the transformation objectives of the Future Combat Systems program," said Anthony Stentz, associate director of the NREC.

"Development of a production-quality Autonomous Navigation System will advance the mobile robotics field and increase the safety of soldiers by eliminating the need for them to directly operate the Unmanned Ground Vehicle (UGV)."

"The Robotics Institute and the NREC are leading robotics research and technology transfer organizations," said Mark Del Giorno, vice president of engineering at GDRS. "Their presence on our team provides us with field-tested sensory processing and tactical planning as we jointly develop the ANS."

During the past three years, the National Robotics Engineering Consortium has served as the prime contractor and systems engineer for four technology development programs directly related to Future Combat Systems Unmanned Ground Vehicles. The NREC Unmanned Ground Combat Vehicle (UGCV) team designed and built a six-ton, fully invertible, six-wheel drive hybrid electric vehicle suitable for armed reconnaissance missions. Another NREC team was recently selected to build a half-ton, highly mobile UGV for the US Marine Gladiator program. The Marines also funded the Robotics Engineering Consortium to build Dragon Runner, a portable robot or "throwbot" that military personnel can throw over a wall or into a building to support urban reconnaissance missions.

The NREC is also leading a team into Phase III of the Defense Advanced Research Projects Agency's PerceptOR program to further develop and test autonomous navigation systems for off-road terrain.

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