The aim of this book is to provide an advanced introduction to inertial data processing (determination of attitude, velocity, and position) along with design architectures and algorithms used to aid the inertial navigation system (INS). The emphasis is on the high-end sensors and systems used in aerospace applications (known as ‘navigation grade’ or ‘nav grade’). The subject of inertial navigation systems and how to aid them is complex and multi-disciplinary. Mathematics and physics along with electrical, mechanical and software engineering all are involved. This book has been written to serve as an introduction for students and those new to the field.

Link to purchase: https://www.amazon.com/Fundamentals-Inertial-Navigation-Systems-Aiding/dp/1839534125

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On this Memorial Day we gratefully remember those who have given their lives in the defense of our country. In this post, however, I would like to direct your attention to an article about a hero of World War I who by all rights should have died in the war but amazingly did not.

This article about Henry Johnson (by Jake Rossen of Mental Floss) recounts an incident which reads like it was lifted out of a Hollywood blockbuster. Two guys with no functioning rifles successfully fight off several dozen enemy soldiers and hold the bridge they were guarding.

Many, many Americans have heard of Sergeant Alvin York and his incredible feats during the Great War. Hollywood indeed did make a movie about him. It’s long past time, though, for all of us to know about Henry Johnson. Are you listening Hollywood?

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As described in Alan Cameron’s online article about the webinar: “With an opening section covering inertial performance and error characteristics, a core presentation on this new inertial chip technology, and a concluding segment demonstrating the advanced functionality of an autonomous vehicle employing this technology, the in-depth technical presentation will bare valuable information and insight for all those interested in autonomous navigation.”

Registration is open here.

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During the 2018-2019 academic year, an Ohio University Electrical Engineering senior design team, under my supervision, created a website to archive the performance of the four global navigation satellite systems (GNSS): the U.S. GPS, the Russian Glonass, the European Galileo and the Chinese Beidou systems. The website is: www.gnssperformancemonitor.com

Four ublox receivers, each configured to track only one of the four constellations, are connected to an antenna mounted on the roof of the Ohio University Russ College of Engineering building (known as Stocker Center) in Athens, Ohio.

Using the data collected from the four receivers, the website enables users to view horizontal scatter error plots (heat maps) and compare a variety of performance metrics such as horizontal position error, vertical position error and DOPs. Users can view data collected over the past day, week, month, year or the entirety of the data set. Although the website has only been in operation for a few months, some interesting performance characteristics have been noted. As indicated in the plots above, the GPS 2drms error is generally about 2.5 meters. Galileo is typically about 5% better than GPS (notwithstanding the week-long outage that Galileo had back in July of this year). Although Beidou’s performance is typically a factor of three worse than GPS or Galileo, this is explained by the fact that the Beidou constellation is still being deployed and coverage thus far has been concentrated over mainland China. Finally, Glonass is typically a factor of four to five worse than GPS or Galileo and is at least partially due to the FDMA nature of the legacy signals.

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With Sunday’s crash of a Boeing 737 MAX 8 (Ethiopian Airlines Flight 302) following just four and a half months after a so-far unexplained crash of another 737 MAX 8 (Lion Air Flight 610), the public is understandably on edge. Two almost brand new airplanes crashing shortly after take-off with no obvious explanations has prompted numerous airlines and regulatory bodies worldwide to ground the aircraft. Some travelers in the United States are nervous due to the fact that neither the Federal Aviation Administration nor any U.S. air carriers have followed suit.

Unfortunately, this is not the first time 737s have been involved in hard-to-explain accidents. On March 3, 1991, a 737 (United Airlines Flight 585) rolled over and plunged straight into the ground while on approach to the Colorado Springs airport. All 20 passengers and 5 crew were killed. After 20 months of investigation, the NTSB could not find a cause (Dec 8, 1992 accident report). Then, on September 8, 1994, another 737 (USAir Flight 427) spiraled almost straight down into ground while on initial approach into the Pittsburgh International airport. All 127 passengers and 5 crew were killed. Although problems with the hydraulic systems that control the rudder had been suspected, it was not until June 9, 1996 that investigators had sufficient data. On that date, Eastwind Airlines Flight 517, also a 737, experienced a temporary rudder malfunction. Since the malfunction was temporary, and the plane landed without further difficulty, investigators were able to interview the pilots and study the aircraft. Still, it would be another 5 years before the NTSB would issue an amended report on the United 585 accident citing the rudder system malfunction as a probable cause. The amended report was issued almost exactly 10 years after the accident.

The flight control software of the new 737 (and specifically the part known as the Maneuvering Characteristics Augmentation System), is being investigated for its potential role in the Lion Air crash. What role it may or may not have played in the Ethiopian Airlines crash is yet to be seen. With modern flight data recorder and simulation capabilities, the mysteries of the current crashes will likely be solved relatively soon. Humans aren’t perfect and neither are the machines we build. What is imperative, however, is that we learn from the tragedies and strive continually to improve safety.

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Although the ability to locate and disable intruding drones is clearly important, the ability to locate the drones’ operators and take them into custody is, arguably, equally important. This, however, is even more difficult. The tech community created a product category that has finally been used in a grossly nefarious manner. The tech community must now step up and provide the means to catch the criminals who do so.

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Boeing 747

Over the past week we observed the 50th anniversary of the roll-out of the first Boeing 747 (September 28, 1968) and the 60th anniversary of the first transatlantic passenger jet flight (October 4, 1958). The transatlantic passage was flown on a De Havilland Comet (see top picture). Check out FlightRadar24’s blog post on it. The Comet was significant for being the first passenger jet aircraft. It also holds the dubious distinction of being the aircraft that taught the commercial aviation industry a hard lesson about metal fatigue. Three times over the course of 1953 and 1954 a Comet literally broke apart in mid-air resulting in the deaths of all aboard. Subsequent investigations proved the cause was metal fatigue resulting from repeated pressurization/depressurization cycles. Aircraft design techniques were changed (e.g., use rounded windows instead of square ones) including a later version of the Comet that flew the transatlantic flight. De Havilland, however, never fully recovered from the early incidents.

Boeing, however, had waited in the wings instead of charging ahead with the development of a passenger jetliner. The company’s hesitancy to invest in the new paradigm paid off handsomely. Boeing’s first passenger jet, the 707, incorporated the lessons learned from the Comet accidents and was a huge success. Then, a mere 10 years after the first transatlantic passenger jet flight, Boeing rolled out the 747. A mere glance at the two aircraft reveals the enormous design differences. The 747 went on to become the ‘Queen of the Skies.’

For more details on the early Comet incidents, check out the BBC’s article on “The Crashes that Changed Plane Design Forever”. 747 development was not without some of its own drama as is described in an excellent article at Bloomberg: “Boeing’s Iconic 747 Turns 50: A History in Pictures.”

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For the third time in two months, China has launched a pair of Beidou satellites into orbit. This is light speed considering that launches of single satellites a few months apart is normally considered fast. GPS World reports that the recent pair, launched September 19, are the 37th and 38th satellites launched as part of the Beidou program. Although most of those were experimental satellites, the BBC reports that China has now launched 15 of its planned 35 satellite constellation. A more detailed history of the Beidou program is available in an article at GlobalSecurity.Org. In an era of increasing mistrust between the U.S. and the People’s Republic of China, the acceleration of the Beidou program comes as no surprise.

Image Reference: https://gbtimes.com/china-launches-pair-of-beidou-3-navigation-satellites-from-xichang

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The successful evacuation of an enormous number of allied troops at Dunkirk (May 27 – June 4, 1940) might well be argued to be the first serious failure of the Nazi war machine. Although dramatized last year in the movie ‘Dunkirk’ and featured later last year in the movie ‘Darkest Hour’, public awareness is extremely poor regarding those who were left behind. Although the evacuation, code-named ‘Operation Dynamo,’ successfully rescued over 300,000 allied troops, tens of thousands were left behind. These men were either executed or horribly abused as prisoners-of-war. It would be five very long years before the survivors were liberated and brought home.

Operation Dynamo was obviously hugely successful both for rescuing the bulk of the British Army and for boosting the morale of the British people. Britain would essentially ‘go it alone’ for the next year-and-a-half until the United States entered the war. Shortly after Dunkirk, President Roosevelt committed the US to providing aid but under existing law, it had to be paid for with cash. Very soon Churchill informed Roosevelt that Britain simply had no resources to pay. The Lend-Lease Act, through which the US provided war materials to Britain (as well as the Soviet Union and China) was not proposed until December 8, 1940 and did not get passed into law until March 1941. In the mean time, Hitler tried to gain air superiority with the Battle of Britain (July – Oct, 1940) and tried to extinguish British morale via The Blitz (Sept 1940 – May 1941). Through British determination and resolve, both Nazi operations failed.

We all know the Allies won and the first step in that direction was the successful evacuation at Dunkirk. However, on this Memorial Day, let us remember the terrible cost of that victory. We honor all those who fought, and especially those who made the ultimate sacrifice, on our behalf.

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As reported yesterday by CBS-affiliate KMOV in St. Louis, first responders in the city of Belleville, Illinois (about 5 miles southeast of St. Louis) used drones to surveil rooftops as part of their investigation of ‘credible threats’ made against students at the Belleville East and Belle West High Schools. The drones provided visual observation to ensure the rooftops were clear. The Belleville Fire Department has been operating drones for two years and has six department members trained in their use. Other applications include searches for missing persons and even delivery of life vests to persons in distress in the water (recall the St. Louis area is situated along the Mississippi River).

With a population of approximately 42,000, Belleville does not have the resources for manned helicopters. The drone shown in the KMOV video clip appeared to be a DJI Inspire 1 that currently retails for approximately $1400 (the upgraded Inspire 2 is approximately $3k). In the hands of properly trained operators, drones are providing much-needed low-cost ‘eyes in the skies.’

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