VPI Technology Case Studies
GLOBAL COMMERCIAL SHIP TRACKING SYSTEM ON INTERNATIONAL SPACE STATION
JAMSS America approached VPI about designing a new receiver system that would be mounted into the International Space Station (ISS). The purpose of the system was to track collision-avoidance signals that are already installed onto all commercial ships worldwide, called AIS (Automatic Identification System). The current systems allow ships that are near to each other to track each others’ progress and ensure that they do not collide. However, it’s a localized solution, and the customer’s objective was to create a worldwide view of all commercial vessels by tracking the signals from space.
Design a system that will collect collision-avoidance signals from all commercial ships worldwide from the International Space Station and transmit the data through NASA’s datalink for mapping on a 3D globe.
Designing a circuit board that can survive the harshness of space, and be extremely reliable, as component repair/replacement would be very costly.
Designing a receiver that could accurately identify the faint AIS signals from 240 miles in space, and filter out all other electronic noise.
Designing the system that could account for the Doppler effect on the AIS signal as the ISS flies at 17,500 mph in an elliptical pattern over the Earth’s surface as it rotates.
The data flowing from the AIS receiver system is translated onto a stunning 3D global map, with the ability to zoom in on a given area and see all ships, very near to real-time. Users can click on a particular ship and see its name, location, heading, whether it’s underway, and other data points. VPI is glad to have been part of this exciting project.
VPI designed a circuit board ready to withstand the harsh environment of space. For maximum reliability, we designed the board with five radiation-hardened “supervisor” microprocessors that monitor the status of three redundant single board computers and two redundant software-defined radios. These processors were implemented using a “voting” scheme: if one or two of the processors failed, the others would out-vote the aberrant behavior of the failed processor and continue normal operation. The system monitors its own health and up status, and automatically reboots if needed.
The system collects the AIS signal from ships as the ISS passes over the Earth. The frequency of transmissions can shift higher or lower depending if the ISS is traveling towards or away from the transmitting vessel—essentially, the Doppler effect. To deal with this variation, VPI designed the system with eight virtual radios which are tuned to the surrounding frequencies so that it accurately receives the signals. This strategy works very well, even though the ISS is traveling at 17,500 mph in space, orbiting the earth once every 92 minutes!
VPI firmware engineers also designed the system for remote firmware upgrades that could be performed through NASA’s wireless datalink to the ISS. This allows for code upgrades and changes as needed without requiring the astronauts to touch the equipment, which was especially critical in this situation.
The enclosure and all wiring harnesses were designed by VPI mechanical engineers to fit the specifications of the available space in the ISS and to ensure secure and durable connections.
This was a particularly challenging test situation—there was no real way to fully test the system in its environment in space until it was actually deployed. VPI engineers worked with engineers at NASA in Houston to conduct land-based tests and put the system through its paces as much as possible beforehand.
In late June 2016, the box was loaded onto a Space-X rocket and traveled to the ISS, where astronauts installed it. There was plenty of anticipation in the VPI office as we awaited word! But the news was exactly what we hoped for—the system was turned on, came up, and performed exactly as expected. This was a real testament to excellent engineering design and execution by our VPI engineers and teamwork with our customers and partners.
US CAPITOL BUILDING TO RAYBURN OFFICE BUILDING SUBWAY CARS UPGRADE
In the basement of the U.S. Capitol building in Washington DC, a series of subways connect to nearby office buildings for the House and Senate. This allows those serving in Congress to move quickly between their offices and the Capitol building, particularly when they need to be on the floor for discussions and votes.
The Architect of the Capitol, a prestigious federal government agency tasked with stewardship of the landmark buildings and grounds of Capitol Hill, contracted with VPI to update the electronics, motors, and control systems of the two subway cars that traverse between the Capitol building and the Rayburn House Office Building. These cars were originally installed in 1965, and the electronics were outdated, difficult to replace, and not as reliable as desired.
Completely redesign and install all-new electronics, motors, control systems, and wiring in the two subway cars running between the U.S. Capitol building and the Rayburn House Office Building.
Designing a complete system that allows the operator of the car to simply push one lever, which will start the car smoothly, ramp up to maximum speed, and then slow down and stop smoothly, providing a comfortable ride for the passengers.
Gaining a full understanding of electronics installed over 50 years ago, often without documentation, and designing a new, robust, modern system that duplicates or improves the performance.
Completing the full onsite installation within a short window while Congress is on recess.
Both cars are now operating with the upgraded systems, and are working very well. The operators enjoy the ease of operation, and the system now actually travels slightly faster between the two stop points than before. Riders have commented that the subway cars are now much smoother and quieter.
VPI first performed an exhaustive onsite review of the current electronics and mechanical systems, along with the list of issues and desired upgrades from the Architect of the Capitol staff. Our engineers then went back and completed their design work. The three main areas of focus included:
- Driver’s panel
- Control system
- Drive system
Our engineers designed a completely new control panel, with buttons and controls that are easy to understand and operate. The customer requested a system with single-lever operation that would automate the speed controls as the car travels between the stations.
VPI engineers designed the underlying control system for the main drive motors that propel the cars, and also the motors that automatically open and close the doors (with the ability for the operator to manually override).
They also designed a completely new drive system, with new motors and associated electronics.
After the design work was done, all hardware and materials were ordered and shipped to Washington DC.
The firmware controls for this system consisted primarily of programmable logical controller (PLC) code to control the operation of the motors.
The timeframes were a particular challenge for this project. Congress goes on recess each August, and the Architect of the Capitol staff wanted to get the upgrades done for both cars during the break so they could minimize the impact on users. This left approximately five weeks to get everything done. Our engineers worked long days to get it done in time, with considerable advance preparation and coordination to maximize their time working on the upgrades.
They upgraded one car at a time. They ended up pulling out every single wire in the cars, replacing the motors, installing all electronics, the new control panels, and other control-related hardware and wiring.
One of the project objectives was to create more legroom for the operators. This was achieved with some creative design work, aided by the smaller space requirements for modern electronics and controls.