The STIM300 is a small, tactical-grade, low-weight, high-performance non-GPS aided IMU. It contains three highly accurate MEMS gyros, three high-stability accelerometers and three inclinometers. The IMU is factory calibrated and compensated over its temperature operating range.
The STIM series is designed for use below and on the ocean, on land, in the air, and in orbit and space. The STIM300 IMU is well suited for stabilization, guidance and navigation applications in the industrial, aerospace and defense markets. It is a crucial building block for inertial navigation systems in UAVs, AUVs, AGVs, UGVs and ROVs, Sensonor said.
The STIM300 is also used for camera turret stabilization and for use in various handheld devices that require a small IMU to secure operations during GPS outage.
JAVAD GNSS is introducing its new unmanned aerial vehicle with the dramatic flourish of a video showing the UAV in flight, accompanied by the “Also Sprach Zarathustra” theme from 2001: A Space Odyssey.
The TRIUMPH-F1 unmanned aerial vehicle is based on the JAVAD GNSS TRIUMPH-1. TRIUMPH-1 is the company’s field-tested high-precision geodetic GNSS receiver with 864 channels to track all current and future GNSS signals.
When used on the ground, the TRIUMPH-F1 can function as a TRIUMPH-1 base or rover. The four motor arms (for eight motors) are detachable. There are four screw inserts in the bottom to attach the TRIUMPH-F1 to a pole mount for field use.
The 3DM-GX4-45 by LORD MicroStrain is a miniature, industrial-grade GPS-aided inertial navigation system that uses high-performance MEMS sensor technology. It combines a triaxial accelerometer, triaxial gyro, triaxial magnetometer, temperature sensors, pressure altimeter, and dual on-board processors running a sophisticated Extended Kalman Filter (EKF) to provide excellent position, velocity, and attitude estimates.
It offers a range of fully calibrated AHRS measurements, including acceleration, angular rate, magnetic field, deltaTheta and deltaVelocity vectors. GPS measurements include LLH position, ECEF position and velocity, NED velocity, UTC time, GPS time, and SVI. The receiver is a 50-channel u-blox 6, which receives GPS L1 C/A code, and the SBAS signals WAAS, EGNOS, and MSAS.
The 3DM-GX4-45 provides accurate navigation and orientation under dynamic conditions for applications such as GPS-aided navigation; unmanned vehicle navigation; camera stabilization; robotic control; and reconnaissance, surveillance, and target acquisition.
A few weeks ago at the Esri 2014 International User conference in San Diego, California, we conducted our first live event webinar from a Plexiglas booth sitting among many of the 14,000+ attendees buzzing around inside the San Diego Convention Center.
The webinar focused on high-precision GNSS on mobile devices (iOS/Android/Windows), unmanned aerial systems (UAS), and real-time GIS transactions. These are hot topics in the geospatial world, and that was confirmed when I received about 100 pre-webinar questions and more than 100 post-webinar questions.
In my article this month, I’ll do my best to provide answers to the questions asked. If I don’t get to your question, or if you have another, please email me at [email protected].
First of all, if you didn’t attend the webinar and would like to view the recording, you can register here and you’ll be provided a link to view it. It’s a great, interactive discussion. I grabbed Sharad Garg, iOS consultant, from the Esri show floor to talk about the intricacies and complexities of using GNSS receivers on iPads and iPhones.
Without further delay, following are some of the more popular pre- and post-webinar questions I received.
Mobile Devices
First, I’ll start with the questions about mobile devices and high-precision GNSS.
1. Will Android be the dominant mobile tablet platform in the Enterprise?
It’s hard to say. I recently met with a group of enterprise IT professionals and we were discussing this issue. Basically, the group was equally divided into thirds. One third were using Android. one third were using iOS, and one third were using Windows.
Android advantages: Lots of mobile devices available that run Android. Android disadvantages: Open source = non-standard implementations, so app software may not run on every device; security concerns.
iOS advantages: Consistent user interface, consistent software development environment, popularity of iPad and iPhone. iOS disadvantages: Closed ecosystem (very limited number of tablets); doesn’t interface to devices (such as GNSS) that haven’t been through the Apple certification process; security concerns.
Windows advantages: Security; lots of legacy apps and utilities written for Windows. Windows disadvantages: Limited number of tablets being deployed based on Windows.
For enterprise organizations, data security is a huge concern. Since Android is open source and gaining the most market share (at least in the consumer market), it’s got a target on its back for hackers. That’s the biggest concern I hear from corporate IT professionals. How will Android device developers address that, or will they? The consumer market for Android devices is exploding regardless of security. Do they even care about the enterprise market? Apparently Apple does as it recently signed an agreement with IBM to address the enterprise market, with IBM committing to deploying more than 100 enterprise solutions for iOS.
Site of the webinar broadcast from the Esri UC.
2. Which mobile platform is the most universal/easy to integrate with GNSS receivers?
Out of the box, Windows and Windows Mobile devices are still the easiest to interface to external GNSS receivers for the average consumer. Using Bluetooth, serial or USB, NMEA (or proprietary binary) data flows easily via the device com port or virtual com port. If you’re using a Bluetooth interface, there is some inconsistency among mobile devices due to the different versions of Bluetooth management software used on mobile devices, but it’s workable, and worst case you can buy an inexpensive third-party Bluetooth software manager like BlueSoleil.
With the use of an app such as Bluetooth GPS that allows you to select an external GNSS receiver, connecting your Android device to an external Bluetooth GNSS receiver is relatively painless.
Apple products are the toughest to integrate with external GNSS receivers via Bluetooth. Each GNSS receiver has to be specifically designed with an Apple Bluetooth authentication chip and be subjected to the Apple certification process, which can be lengthy and costly. This is the reason why you see very few Bluetooth GNSS receivers available for Apple products. The good news is that once the GNSS receiver is approved, the Bluetooth connection happens automatically when the GNSS receiver is in range of the Apple device. No com port config, no baud rate to worry about, etc.
3. What is available on Android that will make my smartphone a practical and useable tool that can assist in collecting professional data?
First of all, you need to find a high-precision Bluetooth receiver to connect to your Android device. Then, establish the Bluetooth partnership between the Android and GNSS receiver (scan for Bluetooth devices, enter passcode, etc). Once you have that, download the Bluetooth GPS utility I mentioned above and it will allow you to select which GNSS device to use (external vs. internal). Once you’ve selected the external GNSS receiver and connected to it via Bluetooth, every location app on your Android device will use the high-precision GNSS receiver for location.
This applies to an Android tablet or Samsung Galaxy phone. Take a look at this article to see how I ran RTK on a Samsung Galaxy using a Bluetooth RTK receiver.
Today’s challenge is finding “professional” GIS data collection apps that run in the Android environment. There are a few, but the selection is limited. Esri has its Collector for ArcGIS app that runs on Android, but it requires an ArcGIS server backend or ArcGIS Online account. Other data collection apps like Fulcrum and Amigocloud run on Android as cloud-based services.
4. Is there an actual GPS receiver within smartphones, or are they triangulating off of cell towers?
There’s a GNSS receiver in virtually every smartphone manufactured. The GNSS chips are so cheap (a few dollars) compared to the functionality gained that it wouldn’t make sense not to design a GNSS receiver in a smartphone. Now, just because there’s a GNSS chip in each smartphone doesn’t mean it’s the only technology used for location. For example, Apple iOS uses multiple data sources to determine the location at any given time. It will use a combination of cellular triangulation, Wi-Fi IP address, and internal GNSS receiver and external GNSS.
5. Which applications do you see requiring RTK accuracy within the mass-market applications?
A couple of years ago at the GPS World Leadership Dinner at the ION GNSS conference in Nashville, Dr. Todd Humphreys of the University of Texas at Austin predicted that you’ll have RTK (real-time centimeter accuracy) capability on your smartphone by the year 2020. I agree with his prediction, and I think we’ll see inexpensive Bluetooth RTK “pucks” well before 2020, as I’ve written before.
Often, I get the question raised above. Who needs RTK on a mobile phone?
I can’t tell you any more than that in the early 1970s when GPS was first being conceived, not one could tell you what GPS would be used for today. I love the following quote from Steve Jobs: “People don’t know what they want until you show it to them.”
6. Since many devices are complete systems with GNSS inside, do you see the direction of the industry moving towards remote “add-ons” like Bluetooth receivers?
Bluetooth receivers are certainly trending, and it’s primarily driven by the explosion of powerful yet inexpensive tablets and smartphones in the past five years, starting with the iPad/iPhone, and now with Android devices and smartphones in general. People want to use their consumer devices in a professional capacity and some need high-precision GNSS receivers, so that’s driving the demand for “add-ons” like Bluetooth GNSS receivers, laser rangefinders, and more.
Unmanned Aerial Systems
Ok, let’s transition to some questions on UAS (such as UAV, drones).
1. Do you see the FAA allowing simple operations for very low altitude UAV-sensors?
It’s difficult to speculate what the FAA will implement, but I have to think, based on its past behavior, that the initial rules will be super-conservative with minimum requirements being that a licensed pilot will be required to operate the UAS in addition to strict equipment requirements.
What’s going to be interesting to observe is what the FAA will do about the hundreds (maybe thousands) of UAS operators who will attempt (or are attempting) to “fly under the radar” and skirt the FAA rules. We’ve seen the FAA attempt (sometimes successfully and sometimes not) to crack down on some UAS operators whom it believes are violating the rules, but there have only been a handful of those cases.
2. When do you think the FAA will release rules for commercial UAV users?
I wouldn’t be surprised if the FAA issued some guidelines in September 2015, but I seriously doubt they will publish the full set of rules by then.
By the way, I attended an interesting UAS presentation at the AEC Summit prior to the Esri UC. You can see my write-up of it here.
That’s it for now. I’ve got many more questions from the audience that I’ll address in upcoming newsletters. Stay tuned and feel free to email me directly at [email protected].
Trimble has announced that Mesa County in Colorado has received a Certificate of Authorization (COA) that will allow the Public Works Department to operate its Trimble UX5 Aerial Imaging Solution throughout the county. A COA is an authorization from the Federal Aviation Administration (FAA) allowing the operation of an unmanned aircraft in a designated area and not for commercial use.
The authorization is currently required to legally operate a public unmanned aircraft in the U.S. The COA was granted to the Mesa County Sheriff’s Office, who manages the county’s unmanned aircraft system (UAS) operations and has been flying systems since 2008.
Mesa County’s Public Works chose the Trimble UX5 for a variety of applications including determining volumes and compaction of its county landfill, surveying and monitoring capital improvement projects such as roads and bridges, as well as assist the Mesa County Sheriff’s Office or other county departments, as needed. “With the Trimble UX5, Mesa County is one of the first to benefit from a cutting-edge solution that can change how surveyor’s collect data,” said Frank Kochevar, GPS/Survey Supervisor for Mesa County Public Works. The Trimble UX5 was used by Mesa County Public Works to gather aerial images of the landslide that occurred in Western Colorado in May of this year.
“Trimble’s goal is to allow geospatial professionals to quickly and efficiently capture and convert existing field conditions into actionable information for their customers. We are pleased that Mesa County will now be able to apply the Trimble UX5 Aerial Imaging Solution to meet their public works department needs,” said Phil Sawarynski, business area director for Trimble’s Geospatial Imaging solutions.
Mesa County has received multiple COAs since 2008 from the FAA for public safety purposes. This is the first COA issued to the Mesa County Sheriff’s Office that will be used specifically for aerial mapping on surveying and engineering projects, in partnership with the Public Works Department. According to Ben Miller, UAS Program Director for the Mesa County Sherriff’s Office and coordinator for all their COA’s, “In collaboration with Trimble, Mesa County, Colorado continues to demonstrate that small unmanned aircraft are not just a tool to save lives, but a community asset that can help save its citizens tens of thousands of tax payer dollars.”
The Trimble UX5 is an unmanned fixed-wing aircraft targeted at the surveying, oil & gas, mining, environmental and agriculture industries. The system autonomously captures a series of high-resolution images during flight, which is typically up to 50 minutes covering as much as 2.3 square kilometers (approximately 1 square mile) when flying 120 meters (approximately 400 feet) above the ground. Using Trimble Business Center Office software, images are used to easily generate 2D and 3D deliverables such as orthomosaic images, three-dimensional point clouds and contour maps. The Trimble UX5 enables the collection of large amounts of data, often faster than traditional surveying technologies.
If you’d like to experience an industry first, I think, I’ll be participating in a live webinar being held during the Esri conference at the San Diego Convention Center on Thursday, July 17, at 10:00 a.m. U.S. Pacific time. I’ll have some planned guests, and perhaps drop-in guests, discussing the complexities of integrating mobile devices with disparate operating systems (Android, iOS, Windows, Windows Mobile, Windows Phone) into your GIS workflow. If you’re at the conference and would like to see us in action, stop by the podcast booth near Room 27 of the convention center. If you’d like to tune in live via the Internet, please sign up by clicking here.
This week is the mecca of GIS, at least in the U.S.; the Esri International User Conference (UC) in San Diego, California, and I’m swimming in GIS up to my ears.
There’s always a myriad of Esri-centric meetings and events during the weekend prior to the UC, and this year was no exception. During the weekend prior, I attended the AEC Summit, formerly named the Survey Summit. The AEC Summit bills itself as the “Forum for High-Accuracy” GIS.
The dominant technology discussed at the AEC Summit was UAS (aka UAVs, Drones). There was lots of discussion about the forthcoming Federal Aviation Administration rules (due September 30, 2015) and “potential” UAS applications. However, one presentation gave the audience a practical look at the value of a UAS. Burns & McDonnell, in association with the University of Connecticut, reported their company worked nine months to gain approval (Certificate of Authorization) from the Federal Aviation Administration (FAA) to conduct a transmission line inspection using a rotary-wing aircraft.
Steven Santovasi, GISP at Burns & McDonnell, gave a summary presentation of their experience with UAS technology. He started with this slide that frames the UAS device market, divided into three device segments: fixed-wing, rotary craft, and a hybrid version with the hover features of a rotary UAS but the speed and stability performance of a fixed-wing UAS.
Types of UAS used for Mapping
Santovasi reported that using the rotary UAS allowed his company to perform an inspection that he thought couldn’t be performed by a manned aircraft. He said that the UAS was able to get within five feet of the structure and take detailed, high-resolution photos. In fact, he said his team was able to identify a failing bolt that may have caused a significant power outage. He reported that a representative of the transmission line owner said that the discovery of the failing bolt “paid for the project.” The transmission line is strung on a 250-foot-tall tower.
Following is a photo of the bolt (and accompanying structure) taken by the rotary craft UAS. There’s actually a much higher-resolution an close-up photo of the bolt I’ll try to obtain and update in this article.
Failing Bolt Identified by High-Resolution Photo Captured from a UAS at Close Range
There was some discussion in the audience that the FAA may not make the September 30, 2015, deadline, or that it will issue a partial set of rules. Last month, a Washington Post article reported the same. If that happens, it’s going to be really interesting. It seems like with each day that goes by, the heat gets turned up a little more for the FAA to act. More frequently, perhaps fueled by the FAA vs. Pirker case where the FAA was slapped by a NTSB judge for not having enforceable rules to punish “violators,” there are media reports that individuals and companies are using UASs for commercial purposes regardless of the FAA’s position. For example,
However, the FAA is not giving up in its attempt to assert its rules despite the ruling by the NTSB judge. On June 23, the FAA issued a press release offering “guidance to Model Aircraft Operators” in an attempt to squelch commercial UAS operators from believing they can fly under modeler rules.
User Conference Plenary
Every year, I look forward to Esri President Jack Dangermond’s keynote at the plenary. I love that Esri is still a privately held corporation, having only to answer to themselves. They don’t have to worry about Wall Street quarterly reports as publicly-traded companies do, so they can choose to change strategy or take on projects that may not appeal to public shareholders. Given that, you really never know what Mr. Dangermond might decide to do, or say, so it’s always interesting to listen to his thoughts on Monday morning.
Of course, there were tons of ideas shared, some new products introduced, and some impressive fourth-graders speaking to a crowd the size that 99.5% of us will never have the opportunity to address. But, after listening to the plenary, watching Twitter, reading blogs and news releases, etc., I can boil it down to one word where this technology is headed…real-time (or is that two words hyphenated? :-) ). I want current information, and I want information as events occur. That is the definition of real-time. I was struck by the City of Rancho Cucamonga’s presentation, which won Esri’s President’s Award. The city has deployed a GIS that allows it to “see” events as they happen, whether it be a traffic accident, fire or other public emergency. Of course, you can easily extrapolate that to include public works nuisances like potholes, traffic signal outages, and street closures, then further extrapolate to society where you have something like Waze, a mobile phone app that allows millions of drivers to share real-time information about traffic conditions.
City of Rancho Cucamonga Executive Dashboard for Monitoring Municipal Gov’t Activity
In geographic regions where there is solid wireless connectivity, there’s no reason we can’t or shouldn’t have access to real-time information on a broad scale, in a very accessible manner. And of course, geographic location is a super-important part of that real-time information. Accurate, real-time information allows us to make accurate, real-time decisions.
The real-time theme bubbles and oozes from GIS, and GIS is begging to be a real-time technology. This is largely driven by mobile devices and sensors. It’s not like the real-time “transaction,” as Mr. Dangermond has coined in past Esri UC conferences, is a new concept. That concept hasn’t changed. What has changed is the proliferation of mobile devices and sensors that enable us to carry the power of GIS in our pockets. They are the technology enablers of real-time GIS, and the trend is crystal clear. It is what people want, and they will get it because GIS, mobile devices and sensor technologies are converging, and to a price point that is very affordable. This year, Mr. Dangermond mentioned the Internet of Things during the general plenary. This is exactly what I’m referring to. Devices and sensors will each have an IP address, or some method of making themselves known on a network. Some people call this Big Data. Regardless, we’re seeing this transformation beginning.
I saw a great example of the transition from labor-intensive transactions to real-time transactions at a Esri UC presentation this week. It’s a utility company that was using a data check-in/check-out workflow to collect high-precision GPS data for its infrastructure (e.g., valves, meters, etc.). The company was spending a significant amount of time dealing with the data check-in/check-out procedure and data post-processing. Some downsides of the data check-in/check-out workflow listed were:
many opportunities for human or technical error
clunky and arduous QA/QC process
slow and expensive workflow that is difficult to scale
software maintenance cost and overhead
In the past six months, the company transitioned to a real-time data collection process that posts high-precision GPS transactions in real-time within SDE in ArcMap. Some of the benefits listed were:
GPS points update in real-time within SDE
laterals and fittings draw and populate automatically
support for a wider variety of software data collection tools like ArcGIS Mobile, ArcPad (either SDE or ArcGIS Online) or Collector
simple design for tablet use (either online or offline)
software cost reduction (unlimited seats of ArcGIS Mobile w/Server, Collector free through ArcGIS Online)
Perhaps the words that best describe the company’s transition to a real-time GIS transaction workflow were contained in the summary page of the presentation.
Time: Our Most Precious Resource
‘ Nuf said.
Plenary Opening Keynote by Mr. Dangermond
If you want to take a look Mr. Dangermond’s opening keynote, including the presentation by the City of Rancho Cucamonga, following is a 22-minute video that’s worth a look.
Like it or not, as a person who works with geospatial data, UAS (unmanned aerial systems such as drones and UAVs) are in your future. The upside of said technology for “quick and dirty” mapping is undeniable.
GNSS plays a key role with UAS, just like it plays a key role in classical photogrammetry. In fact, UAS may even push GNSS technology into areas where it hasn’t gone. For example, L1 RTK. I wrote about L1 RTK technology several years ago, and while several products attempted to exploit it, L1 RTK never was adopted in any significant numbers, primarily due to the short baseline, clear sky, and longer initialization requirements. However, UAS may change that because, by their nature, they work with short baselines, clear sky environments and require some setup time, at least enough for L1 RTK initialization.
However, before we get ahead of ourselves, the regulatory machine (the Federal Aviation Administration) must publish regulations that provide guidelines on the use of UAS for commercial operations. In June, amidst its recent enforcement actions, the FAA issued its first commercial authorization for mapping UAS over land in the U.S. The FAA issued a Certificate of Waiver or Authorization (CoA) to BP to conduct aerial surveys in Prudhoe Bay, Alaska. According to the FAA, the first flights took place on June 8 and used a AeroEnvironment 13.5 lb. Puma AE fixed-wing UAS with a nine-foot wingspan.
According to a Wall Street Journal article, AeroEnvironment spokesman Steve Gitlin said it took about a year and considerable financial investment to win FAA approval for the BP project. Curt Smith, a director in BP’s technology office, said that manned aircraft are sometimes less expensive per flight than the AeroVironment devices, but that the drones will gather far more data, enabling BP to operate “more effectively, more safely, and at a lower cost.”
The FAA announced that last summer that it issued restricted category type certificates to the Puma and Insitu’s Scan Eagle, another small UAS. The certificates were limited to aerial surveillance only over Arctic waters. The FAA recently modified the data sheet of the Puma’s restricted category type certificate to allow operations over land after AeroVironment showed that the Puma could perform such flights safely.
Texas A&M University Becomes Fourth Operational UAS Test Site
In further UAS news, the FAA announced on June 20 that Texas A&M University – Corpus Christi became the fourth of six UAS test sites to become operational. The FAA issued a CoA for the university to use an 85 lb AAAI RS-16 UAS with a ~13-foot wingspan. The other five UAS test sites are Griffiss (NY) International Airport, North Dakota Department of Commerce, State of Nevada, University of Alaska, and Virginia Polytechnic Institute and State University.
American Aerospace RS-16 UAS. 12’11” Wingspan. 85 lbs.
The FAA UAS Legal Stuff
Despite its setback when an NTSB administrative law judge ruled against the FAA in March 2013, the FAA sternly maintains its position that commercial operations of UAS in the U.S. are strictly prohibited without a CoA. In fact, just this week (June 23), the FAA issued a press release about a Federal Register Notice the FAA published of its interpretation of UAS rules for model aircraft in the FAA Modernization and Reform Act of 2012. In the Act, the Sec. 336 Special Rule for Model Aircraft reads:
SEC. 336. SPECIAL RULE FOR MODEL AIRCRAFT
(a) IN GENERAL.—Notwithstanding any other provision of law relating to the incorporation of unmanned aircraft systems into Federal Aviation Administration plans and policies, including this subtitle, the Administrator of the Federal Aviation Administration may not promulgate any rule or regulation regarding a model aircraft, or an aircraft being developed as a model aircraft, if—
(1) the aircraft is flown strictly for hobby or recreational use;
(2) the aircraft is operated in accordance with a community-based set of safety guidelines and within the programming of a nationwide community-based organization;
(3) the aircraft is limited to not more than 55 pounds unless otherwise certified through a design, construction, inspection, flight test, and operational safety program administered by a community-based organization;
(4) the aircraft is operated in a manner that does not interfere with and gives way to any manned aircraft; and
(5) when flown within 5 miles of an airport, the operator of the aircraft provides the airport operator and the airport air traffic control tower (when an air traffic facility is located at the airport) with prior notice of the operation (model aircraft operators flying from a permanent location within 5 miles of an airport should establish a mutually-agreed upon operating procedure with the airport operator and the airport air traffic control tower (when an air traffic facility is located at the airport)).
(b) STATUTORY CONSTRUCTION.—Nothing in this section shall be construed to limit the authority of the Administrator to pursue enforcement action against persons operating model aircraft who endanger the safety of the national airspace system.
(c) MODEL AIRCRAFT DEFINED.—In this section, the term ‘‘model aircraft’’ means an unmanned aircraft that is—
(1) capable of sustained flight in the atmosphere;
(2) flown within visual line of sight of the person operating
(3) the aircraft; and
(4) flown for hobby or recreational purposes.
You can read more (lots more) about the FAA’s interpretation of the Act here. You can submit a comment on the FAA’s interpretation of the Act here. The comment period ends July 25.
More FAA UAS Legal Stuff
On June 25, the FAA issued a press release announcing that seven aerial photo and video production companies requested regulatory exemptions from the FAA to operate UAS before the FAA UAS rule-making is finalized. According to the FAA, “the Motion Picture Association of America facilitated the exemption requests on behalf of their membership. The firms that filed the petitions are all independent aerial cinematography professionals who collectively developed the exemption requests as a requirement to satisfy the safety and public interest concerns of the FAA, MPAA, and the public at large.”
From the FAA press release, “The FAA published a brief summary of the petition from Astraeus Aerial in the Federal Register. The agency opted to ask for comments only on the Astraeus petition because that company’s request came in first, and the petitions from the other six companies ask for identical exemptions.”
Interestingly enough, the FAA is soliciting public comment before it makes a ruling on the MPAA request, clearly highlighting the tremendous pressure the FAA is under to integrate commercial use of UAS in the U.S.
More Commercial Use of UAS Despite what the FAA Says
The NTSB ruling against the FAA fueled the commercial UAS fire and certainly gave commercial UAS operators, operating illegally according to the FAA, more confidence that the FAA may not pursue them. That might be the case in an incident publicized last week in Seattle, Washington, where a woman called police after she saw a UAS buzzing around outside of her apartment building, believing it was spying on her 26th-floor apartment. The Portland, Oregon-based UAS operator, Skyris Imaging, was interviewed by Portland’s KATU news.
“It was not our intent to view anything other than the views from a 20-story office building that will be built across the street,” said Skyris’s Joe Vaughn. Vaughn told KATU that a Seattle-based developer hired Vaughn’s company to use one of his drones equipped with cameras to take photos of the view for a new 20-story building.
Vaughn told KATU that his company has a fleet of six drones he says he responsibly flies. He told KATU that his company has strict guidelines to never fly for a third party, over crowds, above 400 feet, or beyond visual range. Click below to view the KATU interview.
Live Webinar at the Esri International User Conference
In a GPS World first, we’ll be producing a live webinar from the Esri International User Conference on Thursday, July 17, @ 10 a.m. Pacific Time in the exhibit hall at the San Diego Convention Center. Of course, the webinar will be focused on one of the hottest topics: high-precision mobile GIS. It will cover high-precision GNSS on mobile devices, from iPads to Android tablets to smartphones.
Tune in or join us live from the exhibit hall floor! Register here.
AUVSI Unmanned System 2014 provided a showcase for new UAV/UAS products, and a dialogue on the rapidly growing industry.
Report from the Association of Unmanned Vehicle Systems International (AUVSI) Orlando, Florida, May 12-15, 2014
Just before the start of the huge AUVSI show, the FAA once again cautioned Unmanned Aerial Systems proponents that still more care is needed with UAS airspace access. The majority of UAS operators and manufacturers are making efforts to become compliant with reasonable FAA rules. Also, AUVSI had some good information on the economic benefits of UAS commercial applications to the U.S.
The annual AUVSI conference came down to the Sunshine State this year, and the sun did shine, with temperatures in the high 80s most days. The Orlando Convention Center is a huge place and AUVSI took up the majority of the South Exhibit hall along with a bunch of rooms where most of the technical presentations were run. With close to 600 exhibitors and more than 6500 attendees, this is still one of the bigger trade shows.
FAA Rules
However, just before the start of this huge show, the Federal Aviation Administration (FAA) once again cautioned Unmanned Aerial Systems (UAS) proponents that still more care is needed with UAS airspace access. It’s probably more than a coincidence that FAA released news of a March 22 close call at 2,300 feet between a US Airways airliner on approach to Tallahassee, Florida, and a model F4 Phantom Jet — UAS owner and operator unknown. And CNN also picked it up and animated it pretty quickly. As the industry as a whole strains to seek more airspace access, it’s difficult to understand how incidents like this happen. And, in the process, they push back all the good efforts that are being made by the large majority of UAS operators and manufacturers to demonstrate their ability and desire to become compliant with reasonable FAA rules.
Nevertheless, AUVSI had some good promotional material available at the conference showing the economic benefit to the U.S. for UAS commercial applications — a $82 billion market and around 104,000 jobs over the next ten year, $50 billion in the top ten states alone.
Wildfire mapping, agriculture monitoring, disaster management, power-line surveys, telecomms, weather monitoring, aerial imaging/mapping, TV news and sports coverage, movie making, environmental monitoring and oil and gas exploration — these are just some of the commercial areas where AUVSI anticipates that UAS will generate significant revenue.
Presentations and Sessions
The conference presentations began on Monday afternoon, and one paper that caught my eye was by Sierra Nevada (SNC) on its Fusion Filter, which is designed to take multiple sensor inputs and develop navigation and guidance for en-route, terminal approach and landing. This particle filter maintains thousands of weighted position estimates and refines them to provide a composite position and guidance output. Sensor inputs that SNC has used include 3D radar, lidar, FLIR IR camera, daytime camera, GPS/INS, and digital terrain elevation data (DTED). For landing applications, ~50 algorithms run to determine runway location with or without GPS/INS inputs. SNC has flown development flight tests on both fixed wing and rotor craft.
Tuesday began with a General Session headlined by Rep. John Mica (R-Fla.), House of Representatives; Lt. Gen. Kevin Mangum, deputy commanding general/chief of staff, U.S. Army Training and Doctrine Command; and Rep. Frank Lobiondo (R-N.J.), House of Representatives. In introducing these speakers, Ralf Alderson of AUVSI talked about the change from an industry basically serving the U.S. Department of Defense to a coming UAS commercial marketplace: “Time to start learning about the rest of the world,” he commented.
John Mica chaired the House Transportation Committee until 2012, and was one of the movers behind the government’s legislation that gave the FAA its 2015 deadline to integrate UAS into the National Airspace System (NAS). Mica’s disappointing advice was for us to now think in terms of 10-15 years before there would be complete UAS integration in the NAS, largely due delays in the name of safety by the FAA.
Lt. Gen. Kevin Mangum (Army three-star) began by telling us that the Army’s first UAV may have been the SD1 Drone used in Germany in 1960/61. He indicated that everything the Army does with UAS is basically focused on providing the soldier in the field with the tools he needs to be successful. He indicated how UAS are available at the various command levels, and gave us insight into progress with manned and unmanned teaming.
Frank Lobiondo is chairman of the House Aviation Subcommittee, which oversees the majority of programs of the FAA. He acknowledged that “The rest of the country is not tuned in” to the benefits of UAS, and “sensationalized media coverage only highlights (UAS) in a very negative way.” Nevertheless, Congress is desperate to see the potential economic impact of UAS unleashed, and will urge FAA to speed up the process.
Later on at the conference, almost as if in response to Lobiondo’s comments, FAA Manager of UAS Integration Jim Williams made a welcome announcement. Four companies have approached FAA for expedited UAS approvals, and the FAA is now working with them to expedite limited commercial operations before UAS rules are finalized. Limited commercial operations for filmmaking, power-line inspection, precision agriculture and flare-stack inspection are therefore expected to be soon authorized by FAA.
The next General Session featured presentations by Alaska Lt. Gov. Louis Mean Treadwell and futurist Mike Walsh. While Walsh’s presentation was entertaining and thought-provoking. Challenging almost all status quos for how to conduct business, Treadwell had more to say that was directly relevant for today’s UAS industry. “Do consumers get it, do they want it, do they fear it?” These were the messages Treadwell gave to his AUVSI audience. As a past technology and business start-up innovator, he had a lot to say about the suitability of Alaska for UAS testing and innovation. With 47,000 people working in aerospace in Alaska, and the recently FAA-awarded Alaska-Hawaii based Pan-Pacific Test Range; Treadwell encouraged the UAS industry to come and try Alaska.
Exhibit Floor Highlights UAS Opportunities
Meanwhile, the GNSS and navigation systems suppliers to the UAS industry were going about the business of the trade show — exhibiting and demonstrating their capabilities. Wandering purposefully around the huge show floor, I set about uncovering what was new and how people felt about UAS opportunities:
Septentrio:
Septentrio introduced a new RTK engine this year, which is better in occluded situations — such as under tree canopies or around downtown buildings. It has better scintillation detection and provides clearer warning indicators to users. The bottom line is that its RTK is more robust and works better.
Septentrio has also had some significant success with major dredging operators around the world. It has reduced convergence times for PPP, say when starting with an initial RTK position, and position accuracy degrades gracefully over 15-30 minutes.
Accord:
Accord is quite excited by the prospect of a new FAA TSO C-199, which when approved will establish equipment requirements for gliders, balloons and aircraft such as micro-lights, all without electrical systems. The TSO creates a new class of equipment, which is now referred to as Light Aircraft Surveillance Equipment (LASE). The aircraft targeted for equipage are currently exempt from the rule that mandates other aircraft should carry ADS-B — which broadcasts position and velocity, allowing others in the airspace to track and avoid your aircraft. So to improve safety, a simpler, less expensive ADS-B device is being called for that uses an off-the-shelf (non-certified) GNSS receiver as the position source. The point is if this GNSS is good enough for this special class of aircraft, why wouldn’t it be good enough for UAVs, which are so similar to these targeted aircraft?
Accord has a Micro-i GPS SBAS receiver for this application using a chip-level receiver called the Navika-300, which comes from its Indian technology partners. Accord claims that the Navika is comparable to other chip-level receivers in the market from CSR (Sirf) and u-blox.
Topcon:
Topcon has partnered with MAVinci from Germany to market the Sirius Basic and Pro aerial positioning system in Europe, and presumably this system will find its way into everywhere that Topcon does business.
Achieving 5-cm GNSS-RTK accuracy without traditional Ground Control Points (GCP) increases productivity. Removing the need for placement of GCPs can potentially reduce time for a survey project by up to 50 percent. This precise positioning technology allows image locations developed by Sirius Pro to be used as the equivalent of GCPs.
Trimble:
The Trimble UX-5 Aerial Imaging Rover was probably first on the market as a GNSS/UAS system for precision surveying. Following the acquisition of Gatewing, Trimble has been working hard to bring a fully capable UAS surveying solution to market.
The Trimble UX5 aerial image data is processed into deliverables by the new Trimble Business Center (TBC) photogrammetry module. Specialized computer-vision algorithms produce accurate results automatically, with minimal manual interaction. The UX-5 provides a stable and reliable photogrammetric system delivering excellent results without requiring specialized photogrammetry knowledge or experience.
Trimble also unveiled a new high-performance integrated UHF receiver at the chipset level ( 60 x 55 x 15 millimeters), designed for OEM integrations, UAS among them. The BD930-UHF supports both triple frequency from the GPS and GLONASS constellations plus dual frequency from BeiDou and Galileo, making it ready to take advantage of additional signals as GNSS grows and grows. The BD930-UHF delivers quick RTK initializations for 1–2 centimeter positioning. It also has an advanced kalman filter PVT engine positioning in urban canyons and the like, for applications not requiring centimeter-level accuracy. The receiver also supports fault detection and exclusion (FDE) and receiver autonomous integrity monitoring (RAIM) for safety-critical applications — sure to become increasingly important in the FAA-ruled airspace and coming regulations.
The Trimble BD930-UHF high-performance integrated UHF receiver.
NovAtel:
NovAtel announced the release of the new OEM617D receiver at AUVSI’s Unmanned Systems 2014. The OEM617D is a compact, dual-antenna, dual-frequency, single-card receiver offering NovAtel’s ALIGN heading functionality and RT-2 Real Time Kinematic (RTK) GNSS positioning technology, in both dynamic and static environments. The OEM617D provides dual-frequency operation with GPS, GLONASS and BeiDou signals and also tracks Galileo, SBAS and QZSS, maximizing GNSS availability globally. Fixed and rotary-wing aircraft/UAS, marine, and autonomous ground vehicles will benefit by integrating the OEM617D as well as other applications requiring precise position and heading accuracy.
Gladiator:
The Landmark 50 is a high-performance GPS/inertial product which comes in at the top of the Gladiator MEMS inertial product line. The LandMark 50 INS/GPS represents inertial performance on par with small ring laser and fiber-optic gyros. This performance leap with low-cost MEMS technology offers substantial improvement in performance utilizing the newest high-performance MEMS gyros and accelerometers combined with a 72-channel, 10-Hz update rate u-blox GPS, GLONASS, BeiDou, QZSS and SBAS receiver.
Geodetics:
Geodetics showed off a couple of new GPS/inertial products. The Geo-ReiNAV comes in both a commercial and a mil-spec (SAASM) version. As the team was at lengths to explain, Geodetics is GPS “agnostic” — which in today’s terminology means Geodetics uses a variety of OEM receivers in their products — the smarts are in the filter and processing. The other key component is a Seiko/EPSON G352/362 MEMS Quartz IMU, which apparently has less noise and lower drift (or more accurately “in-run bias stability”) than other silicon MEMS inertials.
Incidentally, we sat and discussed this material at the Geodetics booth, which seemed more spacious than in previous years — it was larger, as it spilled over into the next vacant booth which Hemisphere was supposed to have occupied — but having apparently reserved and paid, didn’t show up for the exhibition.
Sparton:
Sparton released news of the GAINS-10 Multi-GNSS assisted inertial navigation system at AUVSI this year. The unit excels in challenging environments. It provides accurate inertial navigation in the presence of mechanical shock, transient platform vibrations and extreme magnetic interference. The 10DOF IMU features high speed, synchronous sampling of all inertial systems combined with high rate coning and sculling compensation and is fully calibrated over temperature.
Vectornav:
The VN-300 is a miniature dual antenna GPS-aided INS system. The dual GPS adds heading determination, and the inertial aiding helps through potential GPS outages. A pressure sensor is also included for altitude determination. The VN-300 can be used in a wide variety of industrial and military applications and is well suited for size, weight, power and cost-constrained applications such as unmanned vehicle systems; antenna, camera and platform stabilization; heavy machinery monitoring; robotics; and primary or secondary flight navigation.
Oxford Scientific (OxTS):
Last year at AUVSI, Oxford introduced a miniature datalogging GPS/MEMS INS — this year it returned with the xNAV500, which is now real time. With dual GPS and antenna inputs, this unit also provides heading determination in a small form factor that is apparently very affordable.
MicroPilot:
One of the leading providers of autopilot systems for a large number of the UAS at the show, MicroPilot has not stood still during the last 12 months. The latest product addition is the MP2128³× triplex redundant autopilot using three high-performance 2128ɡ autopilot boards on one pcb. The advantage is that this autopilot is fault resistant, providing two additional back-up channels to resist critical function failure. A board-level option is available for integrators who want to combine functions in fewer on-board boxes.
UTC/Cloud Cap:
Cloud Cap is also one of the principle autopilot suppliers to the UAS industry. Cloud Cap appears to pack additional functions into its range of autopilots — including a core autopilot, flight sensors, navigation, wireless communications and interfaces providing data to the payload system. The Piccolo Nano is its smallest device, and has been mounted in a board stack on top of a Cloud Cap enclosure containing a NovAtel OEM615 used as the Nano GPS navigation source.
Overall on par with last year’s AUVSI conference in Washington, D.C., the Orlando venue probably encouraged more industry participation, but there seemed to be a lot fewer military people around. This probably accounts for what looks like reduced attendance over last year.
The GNSS/navigation exhibitors, however, were just as innovative as last year, and were present in good numbers. There was generally good traffic at most of these booths, so there are probably new customers coming directly from the show. What was the most notable new thing at the conference? For me, it was discovering the potential for a reduced scope of equipment certification — provided UAS could find a way to be included within the same class of aviation as balloons, micro-lights and gliders. This would really help bring more UAS with high-performance navigation into usable airspace — even unleashing the commercial potential that Congress and the industry need so badly.
NovAtel has launched the FlexPak-S GNSS SAASM enclosure. The FlexPak-S contains a NovAtel dual-frequency OEM625S receiver card integrated with L-3’s XFACTOR Selective Availability Anti Spoofing Module (SAASM) onboard. The FlexPak-S is security-approved by the GPS Directorate for operational use.
NovAtel made the announcement at AUVSI’s Unmanned Systems 2014, being held this week in Orlando, Florida.
When keyed by authorized defense integrators, the FlexPak-S provides centimeter-level Real Time Kinematic (RTK) Precise Positioning Service (PPS) solution by taking the raw measurements from the XFACTOR SAASM and applying them to NovAtel’s Advanced RTK algorithms. The FlexPak-S can be handled as unclassified when keyed.
In the Standard Positioning Service (SPS) fallback mode, the FlexPak-S continues to provide centimeter-level accuracy by utilizing NovAtel’s dual-frequency civil GNSS positioning engine. FlexPak-S’ fallback mode is configurable for GPS or GPS+GLONASS. Adding GLONASS tracking increases position performance in obstructed sky conditions, which is a benefit for unmanned ground vehicles.
FlexPak-S was developed for size-constrained environments, so it’s compact and lightweight, NovAtel said. Despite its size, the rugged GNSS enclosure has been engineered to ensure reliability, even in harsh environments. The IP67 housing is water-resistant and operates in a wide temperature range. FlexPak-S also allows for easy integration with standardized hardware connections and NovAtel’s comprehensive set of software commands. The SAASM position is provided via a dedicated communication port, as well as through NovAtel’s software command protocol, allowing for maximum flexibility. FlexPak-S uses the same form factor as the FlexPak6 design.
“FlexPak-S is a great option for customers looking for a reliable solution in environments where size is critical, like UAV and robotics applications,” said Shane McEwen, product manager for NovAtel Enclosures. “With standard software and hardware connections, integration is simplified so there is a quicker time to market.”
Applanix Corp. and American Aerospace Advisors, Inc. (AAAI), have agreed on an OEM supply agreement that will incorporate Applanix direct georeferencing technology into AAAI’s unmanned aerial platforms. The collaboration creates a commercially available professional-grade mapping UAV system for civilian applications such as pipeline monitoring, power line surveys and emergency-response mapping.
The availability of the system follows a series of successful test flights of AAAI’s RS-16 Unmanned Aircraft System equipped with Applanix’ DMS-UAV aerial photogrammetry payload with commercially available inertial technology. Joint teams from Applanix and AAAI planned and flew a sequence of missions to evaluate the capabilities, including the ability to provide highly accurate, directly georeferenced and orthorectified aerial imagery without the need for ground control points or aerial triangulation calculations.
The system — consisting of the airframe, its avionics, mobile ground control station, telemetry systems and the digital mapping payload — performed according to expectations and successfully produced high-quality imagery.
The announcement was made at AUVSI’s Unmanned Systems 2014 Conference in Orlando Florida, where the most comprehensive collection of unmanned systems for every domain – air, ground and marine – are on display. A video of the system can be watched here.
“The OEM supply agreement with Applanix formalizes our plans to transform the aerial mapping industry by creating an integrated, professional-grade mapping system for unmanned flight,” David Yoel, CEO of American Aerospace Advisors, said. “For civilian aerial survey projects, this can mean safer operations, lower costs and more efficient deployments while still delivering very high accuracy. We are very pleased to announce the availability of the RS-16 Direct Mapping Solution.”
“We believe this is a ground-breaking development for the airborne imaging systems market,” Joe Hutton, Director of Inertial Technology and Airborne Products at Applanix, said. “There has been a lot of attention on developing a commercial, directly georeferenced mapping solution for UAVs, and now it is a reality.”
The RS-16 with the Applanix DMS payload is available through American Aerospace Advisors directly, for sale to jurisdictions where it is permitted to fly civilian UAV systems.
Visual Intelligence has announced that its iOne Software Sensor Tool Kit Architecture (iOne STKA) is available for purchase or licensing by manufacturers of unmanned airborne vehicles (UAVs) who want to deliver an integrated UAV/geospatial imaging solution to customers.
Capturing high-resolution imagery for applications in engineering, construction, urban planning, military missions and other uses is a significant emerging market for UAV manufacturers, and Visual Intelligence’s iOne STKA makes it possible to bring high-resolution geospatial sensors to UAVs, the company said. By purchasing or licensing Visual Intelligence’s geospatial imaging platform, UAV companies can meet emerging demand for geoimaging solutions that combine the benefits of UAVs with the imaging capabilities of a geoimaging platform.
iOne STKA provides the technology foundation to configure a variety of multi-purpose sensors, including miniaturized 2D/3D applications, for the emerging UVS and mobile/handheld markets. The iOne STKA received the Geospatial Forum 2013 World Technology Innovation in Sensors Award, is the first to be considered for NEANY’s Arrow UAV, and is field-proven by the commercial large-format 2D/oblique/3D multipurpose metric mapping systems iOne IMS, iOne Stereo, and iOne n-Oblique.
With the iOne STKA, the same UAS/UAV sensor system architecture can be used for agricultural and forestry mapping, pipeline or corridor monitoring, utility assessments, aerial surveys, research, persistence surveillance and other metric 2D/3D professional applications. The iOne STKA is a modular multipurpose sensor platform reconfigurable for UAVs of any size. With the iOne STKA, UAV manufacturers are no longer limited to offer monolithic, single purpose DSLR type cameras. Using the iOne STKA technology, UAV end users can economically collect high-quality color or infrared NADIR, oblique, or video imagery as well as co-mount and co-register e.g., LiDAR and thermal sensors using the same system architecture.
“By providing UAV manufacturers and end-users with one reliable and performing end-to-end standard digital sensor system solution for MANY applications, we are empowering our customers with a more efficient and standard technology foundation and paradigm to grow their business, enhance their products, and maximize their return,” said Visual Intelligence President and CEO Dr. Armando Guevara.
At the core of the iOne STKA is Visual Intelligence’s Patented Advanced Retinal Camera Array (ARCA). Developed using open systems and object-oriented software engineering principles, the ARCA is “encapsulated” with a rich set of advanced proprietary software methods that integrate camera components. The ARCA enables the collection of different types of imagery, fused in one pass, producing low-cost, extremely accurate, high-resolution products. It also enables unprecedented array-based collection and functional scalability sensor fusion. The arrays made of these varied imaging devices perform like a single camera, producing one single metric, radiometrically and geometrically correct image, or set of co-registered and fused images; such as a Virtual Frame, of higher accuracy, resolution and quality than DSLR-based monolithic cameras.
Adds Guevara, “UAV manufacturers can take advantage and offer bundled with the iOne sensors Visual Intelligence’s advanced computing technology for fast cloud-based basic and advanced actionable information product generation. As a fully automated solution (from the sensor to the cloud), the iOne STKA includes processing software that uses streamlined workflows and processes imagery faster with multicore/multithreaded/GPU computing technology, making it easy to quickly produce and analyze products in a device-content eCosystem environment. This technology/business model is designed to provide UAV manufacturers and users recurrent ROI.”
UAVs built using sensors based on the iOne STKA have the following features and advantages:
Strong digital obsolescence resilience, extending the useable life of the system while improving operational efficiencies and reducing operating costs for an even better ROI.
In the field:
Collection scalability
Functional scalability
Sensor reconfiguration, e.g. increase collection or functionality as needed or per mission requirements.
Large cross-track and FOV collection through smaller aperture (ARCA enabled).
Ability to collect different sources of metric imagery that can be fused in one pass.
Sensor fusion: Ability to co-mount and co-register in a “small and tight packaging” the EO capability with any other EO or active sensor such as LiDAR, Thermal, IR, etc.
The iOne STKA software architecture is normative across all ARCA-based products; that is, the software is the same for different array configurations or sizes. This reusable component approach yields economies of scale in the manufacturing and use of multipurpose UAV/sensor configurations.
Carrier Phase Compensates for Wind and Wave Motion
Limited landing area as well as interference due to wind disturbance and wave motion make shipboard landings of unmanned aerial vehicles (UAVs) extremely difficult. Use of UAVs at sea can enhance the efficiency of intelligence gathering and surveillance, and could also increase long-range air-strike capability. To successfully land aircraft in such a challenging environment requires a high-precision navigation system; this prototype applies RTK measurements.
By Chiu-Jung Huang and Shau-Shiun Jan
UAVs can perform functions such as surveying, imaging, detection, sensor work, rescue, and geographic information systems (GIS) data collection. The exploitation of UAVs with portable launching and recovery systems using an automatic guidance equipment can enhance their flexibility in many practical applications. In particular, UAVs can achieve great effectiveness from launch and recovery aboard ships at sea. However, the landing area is narrow on a ship, and interference related to the maritime environment due to wind disturbance and wave motions varies greatly, making maritime UAV landings quite difficult. Recovering these aircraft in such a rapid-dynamic environment requires a high-precision UAV navigation system.
Generally, UAVs use a differential GPS (DGPS) aiding station to continuously transmit positioning correction information during landing approach; this method can provide about 0.7 to 1-meter accuracy. However, shipboard landings require more stringent accuracy. According the Joint Precision Approach and Landing System (JPALS), the requirements of shipboard landing include vertical accuracy on the order of 0.3 meters, and the requirement for the vertical protection level is 1.1 meters. To fulfill these accuracy requirements, we have chosen the real-time kinematic (RTK) technique. Recently, researchers have studied the use of RTK satellite navigation. The Boeing Unmanned Little Bird program has been examining shipboard launch and recovery using related navigation techniques.
The accuracy of using RTK navigation is 1 centimeter + 1 part per million.
Figure 1. Flow chart for software-in-the-loop.
Since development of shipboard landing is costly in terms of time and many resources, including human resources, this research is an attempt to evolve a software-in-the-loop (SIL) simulation system to analyze the accuracy of using RTK for landing navigation. The SIL system uses the MATLAB Simulink interface becasue of its helpfulgraphic user interface and block diagrams. A flowchart of the SIL system is shown in Figure 1.
The simulated RTK message provides the navigational data used as the analysis results from the experiments. To ensure the stability of the landing process, the aircraft models were control by a linear quadratic Gaussian regulator (LQG), which is able to reject the environmental disturbances encountered in the landing process. The ship motions were simulated using the factors and the model formulated by the International Towing Tank Conference. A combined position error consisting of the aircraft controls and ship motions was calculated and then fed back to the RTK navigation message.
RTK Performance
RTK navigation provides high positioning performance in the range of a few centimeters; the technique can eliminate main errors, including ionospheric and tropospheric errors and satellite clock errors, among others. A base station and a rover station can cover a service area of about 10 to 20 square kilometers. The data transition should be in real time using a wireless VHF or Wi-Fi modem.
Because data for shipboard landings are difficult to acquire, the navigation message in the SIL was simulated using experiments involving a variety of conditions. In this article, four kinds of experiments were included to help verify the availability and reliability of using RTK information as a navigational message.
We started with a basic kinematic experiment, which was simply used to assess the RTK performance. Next, a relative positioning experiment was conducted to ensure the RTK relative positioning accuracy was adequate. After that, an antenna reversal experiment was designed in order to understand the ship’s swing effect in which aircraft altitude might cause a lack of common view satellites. Finally, an antenna forward flip experiment was conducted intended to show the different RTK positioning results for a variety of sea state effects.
All of the experimental data were collected by a workshop computer through a program data file. The analyses of the results included the mean, standard deviations of positioning error, unavailable RTK percentages and the positioning accuracy when RTK was unavailable. All of the analysis results were imported to the SIL simulation using the Gaussian random variable model.
Figure 2. Kinematic experimental setup.
Kinematic Experiment. The base station setup included an antenna, tripod, and receiver. The rover station setup included a portable vehicle with a battery, antenna, and receiver placed as shown in Figure 2. The data were transmitted and received using a wireless modem for which the transmitted rate was 115200 bps. The receiver was connected to a laptop used as a workshop to monitor satellite quality and collect the data. The region in which the experiment took place is shown in Figure 3: on the roof of the Aeronautics and Astronautics department building at National Cheng Kung University in Taiwan. The red star is the known position of the base station. The broken rectangular red line is 25 meters by 10 meters along which the moving rover station moved clockwise.
Figure 3. Kinematic experimental region.
However, it is difficult to show the true positions of the experiment. In this article, we tried to get the true position by using a linear regression method which used the time, t, as the explanatory variable and the position, y(t), as the dependent variable. The linear regression used the past five epoch positions as the dependent variables by which to obtain the linear polynomial, and the fifth position was put into the polynomial to get the position error. For example, in order to calculate an error at t=4, the position results from t=0 to t=4 must be taken into Equation (1) to form the second order polynomials with parameters P, Q, and R
(1)
The experimental results are shown in Figure 4, which is the ENU positioning error, and Table 1 shows the analysis error mean and standard deviations. The experimental results show that the horizontal positioning accuracy is 0.037 meters (95 percent).
Figure 4. ENU error results for the kinematic experiment.Table 1. Positioning results for the kinematic experiment.
Relative Experiment. This experiment had one base station as before and included two rover stations which were placed on a T-bar, the relative distance being known, on a portable cart as shown in Figure 5. The region of the experiment is shown in Figure 6, where the star marks the location of the base station, with the rover station moving along the black arrow.
The relative error was calculated using a known distance, 0.72 meters, to compare the two rover station positions. Figure 7 shows the relative results of the experiment for which the mean value and standard deviations were recorded in Table 2. In this experiment, only about 4.5 percent of the positioning results failed to meet the requirement of 0.3 meters.
Figure 7. Relative error results.Table 2. Positioning results for the relative experiment.
Common-View Satellite Experiment. Aircraft landing altitude and the ship’s swing motion caused by the state of the sea might affect GNSS information received by the antenna. This experiment had one base station and one rover station at fixed positions as before, but we attempted to flip the antenna of the base station toward the north by 80 degrees, as shown in Figure 8, and the rover station changed direction according to Table 3. The antenna directional change of 80 degrees were chosen for the extreme case that the base station and rover station could experience completely different satellites in view.
Table 3. Common view satellite experimental setup for antenna.Figure 8. Common view satellite experimental setup.
Results of the experiment are shown in Figure 9, in which the vertical lines indicate antenna directional changes. For this experiment, every change is 30 seconds. This experiment demonstrates that the position performance definitely varies. The position analysis is shown in Table 4, which shows a horizontal error of 0.116meters (95 percent).
Figure 9. ENU results of the common view satellite experiment.Table 4. Positioning results for the common view satellite experiment.
Sea-State Experiment. In this experiment, one base station and one rover station were required in a fixed position, but the rover station changed the direction of the antenna, as shown in Figure 10, where the angle of x is decided according to the sea state in Table 5. On the other hand, the antenna changing toward a different direction simulated the swing motion of the boat.
Figure 10. Swing experimental setup.Table 5. Antenna angle in the swing experiment.
The experimental results shown in Table 6 are the mean values, and Table 7 shows the standard deviations. The simulation provides the analysis results in order to authenticate the integration simulations. The results show that the sea state slightly influences RTK positioning.
UAV and Ship Motion Simulations
During shipboard landing processing, many complicated conditions must be taken into account, including crosswinds, an air-wake model, wind gusts, and deck motion. The ship deck motion and crosswind effects are two key factors that further increase the difficulty of ship-borne operations.
For this reason, the UAV controller must have anti- interference features. An LQG controller is able to reject the environmental disturbances encountered during landing in a lateral motion. For the ship deck motion, the chosen spectrum (the International Towing Tank Conference, or ITTC two-parameter spectrum) was used as the power spectrum of the sea waves to be simulated.
Aircraft Simulation. The aircraft was in the simulation, the SP.X-6, was designed by the Remotely Piloted Vehicle and Microsatellite Research Laboratory of National Cheng Kung University (see opening photo and cover). For the longitudinal motion, a combination of a linear quadratic integral (LQI) controller and a Kalman filter in the inner-loop system was used to control the vertical velocity and height mainly using an elevator. For the lateral motion, the LQG autopilots were designed with guaranteed robustness properties that allowed quick return to the designed point.
The SP.X-6 aircraft state functions are shown in Equation 2, in which the x, u, y, w, and v mean the system state vector, input, measurement, process error vector, and the measurement error, respectively. A, B, C, and K refer to the system state matrices, which can be evaluated by the system identifications that are derived by using the subspace identification to obtain an initial model. After that, the initial model will feed into the recursive prediction error method algorithm in order to arrive at further refined models.
(2)
Figure 11. Linear quadratic Gaussian regulator block diagram.
After obtaining the aircraft’s model, the LQG controller is used, a block diagram for which is shown in Figure 11 and for which the close-loop dynamic is given by Equation 3. The means the estimated states are feedback by which to form the optimal control law, u=−K. The y means the output command with the LQG variables F, G, K, and L.
(3)
The aircraft landing controls were divided into the longitudinal and lateral dynamics. For the longitudinal dynamics, the landing command was the vertical discrete height. In the case of the lateral dynamics, the stable condition was used when disturbances were encountered.
Up till now, navigation of SP.X-6 relied solely on the GPS signal. Using RTK technique for the landing process will enhance navigation accuracy. The navigation method is the point-to-point guidance law illustrated in Figure 12.
Figure 12. The point-to-point guidance law.
The basic concept of the point-to-point guidance law can be derived from the aircraft initial position A and the target position B in two-dimensional coordinate frame at every epoch. Desired heading angle θT and the distance between two points d can computed at each control loop via Equation 4.
(4)
The navigation signal used in the simulation is of 20 Hz.
Deck Motion Simulation. Variations in waves are formed by the wind, and waves do not propagate only in one direction; the other direction will also affect wave propagation. The wave always is set as a stationary random process for the purpose of processing. The Longuet-Higgins model assumes that random waves are composed of many different wavelengths and harmonic amplitude superposition. Assuming the wave travels in a fixed direction, the peaks and troughs of the wave lines are parallel to each other and perpendicular to the forward direction of the waves, which are called two irregular waves or crested waves. Crested waves cause greater ship motion. The crested wave model indicates that point a at t epoch on a random sea wave height can be expressed as Equation 5, where ai-th represents harmonic waves with ωi frequency and εi initial condition.
(5)
It can be seen that the wave function can be expressed as a superposition of individual harmonics, so as long as waves establishing harmonic amplitudes and harmonic frequencies can be simulated in order to create the wave model. In this research, the amplitudes and the initial conditions are obtained from the sea wave spectrum of the ITTC model:
(6)
Four different sea state conditions were designed, as shown in Table 8 in the integrated simulation. Using the parameters from the spectrum analysis and the frequency divide method, the sea wave simulation could be obtained. Figures 13 and 14 show the simulation results of sea state A. Figure 15 shows all four state spectrum simulations results, and Figure 16 shows the sea wave height.
Figure 13. Sea State A spectrum.Figure 14. Sea State A wave height.Figure 15. Wave spectrum simulation results.Figure 16. Wave height simulation results.
Integrated Simulations
In the integrated simulation, first the health of the RTK information was examined, and then, according the environment parameter settings, sea wave simulations were conducted. Subsequently, the aircraft landing process errors were presented using the experimental positioning analysis.
The integrated simulation system is shown in Figure 17; it can be divided into three parts. The first part is the sea state options shown in the black line region, and the sea wave change is displayed and the maximum changing rate is calculated after the sea state option is selected. The second part is shown in the green line region that is the landing analysis which includes RTK health status, ENU error size. The last part is the landing animation which is enclosed in the red line region.
Figure 17. Integrated simulations graphic user interface.
Four sea-wave height simulation statuses can be selected, and the chosen sea state can be used to determine the corresponding landing environment, as shown in Figure 18, which illustrates the ship motion simulated by the wave height.
Figure 18. Sea wave change.
RTK health information was simulated according to the experimental results in Table 9, in which the RTK information unavailability was 1.1 percent. A random Gaussian number was used to simulate the health of the RTK satellite information.
After the sea-wave simulation and the RTK health simulation, the second concern was the landing process simulation. The landing process simulation has two conditions, namely the “normal landing” condition and the “landing with common-view satellite problem” condition. The normal landing process errors were presented using the Sea State Experiment results, while the landing with common-view satellite problem process errors was simulated by the result of Common View Satellite Experiment positioning analysis.
For example, a ship was traveling at a velocity of 10 m/s in East, and an aircraft was cruising at a velocity of 20 m/s toward the East. The initial position of the ship was at (ES, NS, US) = (200, 0, 0) and the aircraft was at (EA, NA, UA) = (0,150,100). In the landing process, the desired heading angle and the distance to the waypoint were evaluated every epoch. The simulated landing process example is shown in Figure 19; the blue line is the ship’s trajectory and the red line indicates the aircraft’s trajectory.
Figure 19. The simulated landing process example.
The guidance accuracy includes the control accuracy and the navigation sensor measurement accuracy. In the simulation result, the control accuracy (that is, controller error) was neglected. Therefore, the error for the landing process becomes only the navigation sensor measurement error which was the RTK error in this article. Users have the options to add different controllers as well as the controller error in the simulations.
The landing positioning error was simulated using the imported analysis results in the correspondence sea state included in the RTK status shown in Figure 20 and the landing ENU errors are shown in Figure 21.
Figure 20. RTK state simulation results.Figure 21. The ENU errors of the simulated landing process example.
Red stars in Figure 20 indicate the warning window when the simulated RTK statuses were unhealthy. For example, the 114th, 126th, 169th and 240th epochs in Figure 21 indicate that RTK data is unavailable during this time simulation. The unhealthy RTK signal might cause interruptions in navigation service in the landing process, as shown as the red stars in Figure 21. For the epochs with red stars, the simulated position results were exceeding the performance requirement for RTK shipboard landing. When this situation happened, the monitoring system might raise a flag to the aircraft’s guidance system not to use the RTK signal for landing at this period of time. Excluding these unhealthy RTK epochs, the simulated landing errors were well met the performance requirement for RTK shipboard landing, as shown in Figure 22.
Figure 22. The ENU errors of the simulated landing process after excluding the unhealthy RTK results.
An overall simulation result is illustrated in Figure 23, when the successful landing message was shown in a pop-up window, the landing information of the whole landing process would be shown in the graphic user interface.
Figure 23. Example simulation result.
Conclusions
Experimental results showed that 99 percent of the horizontal positioning was in the range requirement of 0.3 meters. Using the common view satellite experiment and the sea state variation experiment conducted in this study, the limitations of RTK positioning can be understood. Monitoring the RTK status can provide high-quality accuracy with regard to guidance of the landing process. We hope that the results of this study will become a reference for building a shipboard landing system in Taiwan.
Manufacturers
All of the experimental data were collected by a workshop computer through a NovAtel (www.novatel.com) Connect program data file. The base station setup included a NovAtel GPS-703-GGG antenna with a Sokkia tripod and the NovAtel Propak-V3 RT2-G receiver. The rover station setup included a portable vehicle with a battery, a NovAtel GPS-703-GGG antenna and the NovAtel Propak-V3 RT2-G receiver.
Chiu-Jung Huang received her B.S. degree from National Cheng Kung University (NCKU) in Taiwan. She is currently studying for her M.S. degree in aeronautics and astronautics at NCKU.
Shau-Shiun Jan is an associate professor of aeronautics and astronautics at NCKU. He directs the NCKU Communication and Navigation Systems Laboratory (CNSL). His research focuses on GNSS augmentation system design, analysis, and application. He received his Ph.D. degree in aeronautics and astronautics from Stanford University.
