Cargo containers onboard ships are widely used in the global supply chain. The need for container security is evidenced
by the Container Security Initiative launched by the U.S. Bureau of Customs and Border Protection (CBP). One method
of monitoring cargo containers is using low power wireless sensor tags. The wireless sensor tags are used to set up a
network that is comprised of tags internal to the container and a central device. The sensor network reports alarms and
other anomalies to a central device, which then relays the message to an outside network upon arrival at the destination
port. This allows the port authorities to have knowledge of potential security or integrity issues before physically
examining the container. Challenges of using wireless sensor tag networks for container security include battery life,
size, environmental conditions, information security, and cost among others. PNNL developed an active wireless sensor
tag platform capable of reporting data wirelessly to a central node as well as logging data to nonvolatile memory. The
tags, operate at 2.4 GHz over an IEEE 802.15.4 protocol, and were designed to be distributed throughout the inside of a
shipping container in the upper support frame. The tags are mounted in a housing that allows for simple and efficient
installation or removal prior to, during, or after shipment. The distributed tags monitor the entire container volume. The
sensor tag platform utilizes low power electronics and provides an extensible sensor interface for incorporating a wide
range of sensors including chemical, biological, and environmental sensors.
Pacific Northwest National Laboratory (PNNL) has developed the Captive Carry Health Monitor Unit (HMU) and the
Humidity Indicator HMU. Each of these devices provides end users information that can be used to ensure the proper
maintenance and performance of the missile. These two efforts have led to the ongoing development and evolution of
the next generation Captive Carry HMU and the next generation Humidity Indicator HMU. These next generation
efforts are in turn, leading to the future of HMUs. This evolutionary development process inherently allows for direct
and indirect impact toward new HMU functionality, operability and performance characteristics by influencing their
requirements, testing, communications, data archival, and user interaction.
Current designs allow systems to operate in environments outside the limits of typical consumer electronics for up to or
exceeding 10 years. These designs are battery powered and typically provided in custom mechanical packages that
employ sensors for temperature, shock/vibration, and humidity measurements. The data taken from these sensors is then
analyzed onboard using unique algorithms. The algorithms are developed from test data and fielded prototypes.
Onboard data analysis provides field users with a simple indication of missile exposure. The HMU provides missile
readiness information to the user based on storage and use conditions observed.
To continually advance current designs PNNL evaluates the potential for enhancing sensor capabilities by improving
performance or power saving features, increasing algorithm and processing abilities, and adding new features. Future
work at PNNL includes the utilization of power harvesting, using a defined wireless protocol, and defining a
data/information structure. These efforts will lead to improved performance allowing the HMUs to benefit users with
direct access to HMUs in the field as well as benefiting those with the ability to make strategic and high-level supply and
inventory decisions in real-time.
Military missiles are exposed to many sources of mechanical vibration that can affect system reliability, safety, and
mission effectiveness. One of the most significant exposures to vibration occurs when the missile is being carried by an
aviation platform, which is a condition known as captive carry. If the duration of captive carry exposure could be
recorded during the missile's service life, several advantages could be realized. Missiles that have been exposed to
durations outside the design envelop could be flagged or screened for maintenance or inspection; lightly exposed
missiles could be selected for critical mission applications; and missile allocation to missions could be based on prior use
to avoid overuse. The U. S. Army Aviation and Missile Research Development and Engineering Center (AMRDEC) has
been developing health monitoring systems to assess and improve reliability of missiles during storage and field
exposures. Under the direction of AMRDEC staff, engineers at the Pacific Northwest National Laboratory have developed a Captive Carry Health Monitor (CCHM) for the HELLFIRE II missile. The CCHM is an embedded usage monitoring device installed on the outer skin of the HELLFIRE II missile to record the cumulative hours the host missile has been in captive carry mode and thereby assess the overall health of the missile. This paper provides an overview of the CCHM electrical and package design, describes field testing and data analysis techniques used to identify captive carry, and discusses the potential application of missile health and usage data for real-time reliability analysis and fleet management.
The Health Monitor System (HMS) is a low-cost, low-power, battery-powered device capable of measuring temperature,
humidity, and shock. Many mission-critical items are susceptible to shock damage. To help prevent shock damage,
assets often are placed in robust custom containers with shock damping and absorption devices. Assets are still at risk of
damage while in their protective containers. Having a Health Monitor attached to an asset or container allows the status
of the asset to be determined. The Health Monitor can measure, record, store, analyze, and display to the user if a shock
event has occurred that puts the asset at risk of failure. Extensive shock testing and algorithm implementation were
required to develop a Health Monitor that uses a single-point 3-axis accelerometer to determine the type, height, and
severity of a shock event.