Tracking Marine Containers for Homeland Security

By Quick, Tubb, Wempe, and Gretlein

Providing efficient and effective security for U.S. borders, ports, transportation sectors, and other critical infrastructures is a difficult task for the Department of Homeland Security (DHS). Given the massive number of shipping containers that circulate the world, passing in and out of U.S. ports each day, the DHS—through the Small Business Innovation Research Program—issued a challenge to small high-tech businesses to develop a Marine Asset Tag Tracking System (MATTS). The system needed to provide worldwide container tracking, monitoring, and communications in order to help government agencies identify and intercept containers that might have been tampered with prior to their arrival at border crossings or in ports.

iControl, Inc. (San Jose, CA), which has been developing remote monitoring, data acquisition, and control systems since 1989, accepted the challenge. In so doing, it would need to develop a solution that would exceed the capabilities of any and all previous tracking systems. System requirements included:

• The ability to track and locate marine shipping containers while on shore, during loading, and during transit; even while stacked on deck or out of sight in a ship’s hold
• Use of a lower power wireless signal for communication between the tag system, local transmitter, and receiver network
• The ability of local network to monitor and log data during transport and to connect to a central data center once in port
• Use of a reliable and secure power supply that would last a minimum of five years.
 

The most significant hurdles for the iControl team were the requirements for locating containers when stacked and power consumption. Shipping containers are typically stacked both on deck and in the ship’s hold when at sea. On deck, containers can be stacked six high, 12 or more abreast, with up to 20 containers end to end, and still more containers are stored in the ship’s hold. Additionally, stacking density typically allows for less than a foot of space between the containers on all sides. Such close proximity between containers, as well as their possible placement in ships’ holds and staging warehouses before and after delivery, renders useless line-of-sight tracking and communications links like standard global-positioning systems (GPS) or other satellite-based systems.

Simulating the Sea

iControl would turn to National Instruments’ MATRIXx suite of software to develop a control design application, specifically SystemBuild. The company had used the graphical modeling and simulation system for remote control projects in the past.

› › iControl used National Instruments’ MATRIXx software to design this low-power shipping container tracking device that transmits security data from anywhere in the world.

 

iControl began by resolving the line-of-sight limitations of standard GPS tracking systems by using inertial estimators. This inertially augmented GPS system determines container location on board a ship located anywhere in the world, even if the ship cannot connect to a GPS, cellular, WAN, or other cooperative network because of signal reflections or even complete signal blockage. Once the network connection has been severed, each inertial state estimator continues to calculate position information based on embedded gyroscope and accelerometer measurements. It then provides all of this logged information to the network once a connection has been reestablished.

The other important aspect of the MATTS proposal is the minimum five-year operating life. The tag’s power-management system is a multistate system that uses a low-power CMOS timer (1A) to periodically wake the radio receiver. During normal operation, the container tag wakes up the communication receiver to “listen” for a cooperative network carrier from the ship (or dock) gateway. Additionally, the tag accelerometers remain powered during all operations (approximately 3mA)  and are contained in an unobtrusive device permanently affixed to the outside of the container.

‹ ‹ During normal operation, the container tag wakes up the communication receiver to “listen”  for a cooperative network carrier from the ship (or dock) gateway. Additionally, the tag accelerometers periodically monitor the container for large movements that may indicate the container is in transition.

 

The accelerometers monitor the container for large movements that may indicate the container is transitioning to a new state (moving). If the measured acceleration exceeds a predefined threshold, the CPU powers up and propagates the measured motion until the container comes to rest. The minimum power state for the container tag is approximately 4µA (12µW). A stationary tag operating with a 1Amp-hour battery (40cm3) could operate for approximately eight years. Obviously, a container tag does not remain stationary for its entire lifecycle. Under normal operations, the container periodically reports status or recomputes its position while in motion. The relative duration of container movement and status reporting is small yet significant when compared to the stationary state.

Control System Prototypes

To augment the tag power-management system, iControl investigated power scavenging from the tag’s surrounding environment to determine if anything could be used to generate enough power to recharge the battery for an extended life span. iControl did this using the MATRIXx software suite from National Instruments (Austin, TX) to create simulations for evaluating effective power scavenging techniques.

To determine the feasibility of collecting energy from a number of sources, including ambient life, hull vibration, and the motion of the ship while at sea, it would have been impossible to build physical prototypes for each scavenging technique given the cost, possible time involved, and viable solutions.

› › The MATRIXx wave simulator depicts ocean waves hitting the container ship.  It is a random wave generator seeded with observed ocean wave amplitude,  frequency, and probability. (Source: NOAA.)

 

Engineers, instead, used the SystemBuild graphical modeling environment to build dynamic ship-environment models that accounted for ship dimensions, speed, heading, and random ocean waves as well as models for each scavenger. Team members used these models to calculate hull vibration and the ship’s roll, pitch, and heave frequencies as well as to determine the optimal design parameters for their power scavenger. Though capable of generating useful amounts of power, the team decided that solar cells that would convert ambient light to power were the best scavenger.

“We successfully designed a power management system with the assistance of the MATRIXx product family,” says Fred Tubb, president and CEO of iControl, Inc. “This helped us cut 70 percent of our development time on the project by eliminating the need to further test energy scavenging options.”

As a result, only four options were investigated, saving the company a possible $1 million price tag for full-blown tests aboard ships, and solving the riddle to produce a validated container tracking system design inside of six months.

In addition, iControl used MATRIXx to finalize the embedded state estimation algorithms for the inertial estimators.

To date, iControl is nearing completion of Phase II of the proposal and is continuing to develop and refine its MATTS system. The company has several international and domestic pilot programs underway in preparation for full-scale commercialization in Phase III.

Diane Quick is VP of Business Development for iControl and wrote the winning proposal for the Marine Asset Tag Tracking System (MATTS) project. She graduated from the Massachusetts Institute of Technology with a degree in aeronautical and astronautical engineering. Fred Tubb is president and CEO of iControl. He holds advanced degrees in mechanical and control systems engineering from Texas A&M and the University of Colorado–Boulder. Greg Wempe was MATRIXx product manager for National Instruments (NI). He served as Product Marketing Manager for the NI MATRIXx software suite and the LabVIEW Simulation Interface Toolkit.  In addition, Wempe was responsible for the mathematics component of the LabVIEW product line and worked closely with several third-party mathematics partners.  Greg joined National Instruments in 2001 after graduating from Vanderbilt University with a B.E. in biomedical engineering and electrical/computer engineering. Shelley Gretlein is the LabVIEW Real-Time and Embedded team manager for NI. She holds bachelor’s degrees in computer science and management systems from the University of Missouri-Rolla. Send your comments about this article through e-mail by clicking here. Please reference “Marine Containers, July 2006” in your message.

Product Information

iControl, Inc.
San Jose, CA

MATRIXx
National Instruments
Austin, TX