Here are five of the most important issues that developers need to consider when designing an IoT asset tracking system.
A growing application for the IoT is the tracking of assets such as equipment, shipments, and inventory. Knowing what your assets are and where to find them is an important part of business intelligence for many industries, including retail, manufacturing, shipping, and maintenance. The IoT can be a powerful ally in obtaining this intelligence if the asset tracking device has the right design.
Early forms of asset tracking simply logged the movement of assets at a checkpoint using barcodes, Q-codes, or RFID tags to identify the asset and the scanner to create the record. The IoT can, at the very least, automate that process by using an active tag that broadcasts the asset identity to receivers located at checkpoints, without user involvement.
More importantly, though, IoT asset trackers can go beyond checkpoint logging to provide location data for assets. This can translate to greater efficiency in retrieving assets from storage, support geofencing to prevent assets from entering or leaving restricted areas, and help identify assets that are underutilized. Asset tracking devices may also provide environmental monitoring information such as the temperature or vibration history the asset has experienced that might degrade its quality or value.
When developing an IoT asset tracking device or implementing an asset management program using such devices, there are several key issues that developers need to consider. Here are five of the most important.
Indoor vs outdoor
One of the first issues to consider is where the asset will be tracked, because that tends to dictate the kind of communications link the tracking device will require. A system that tracks goods being shipped across town will need a different link from one that tracks the location of assets within a warehouse. Similarly, international coverage may need a different link from that of simple inter-city coverage within a single country.
Indoor tracking might be able to use something like Wi-Fi, Bluetooth Low Energy (BLE), or ultrawideband (UWB) as the communications link. Outdoor tracking might need a low-power wide-area network technology like LoRa, LTE-M, or 5G cellular to provide the coverage required. A system that can track both indoor location as well as outdoor movement in transit will probably require a combination of communication links.
Figure 1 Asset tracking outdoors requires careful consideration of the communications link involved so that it ensures adequate coverage over the asset’s likely movement. Source: LinkLabs
The precision required for location information is another issue that affects the choice of communications link. Tracking an asset in transit with a half-mile location accuracy would be able to use LTE or 5G cellular tower data to triangulate, whereas to obtain location accuracy within 50 meters might require something like GPS or the 5G-based Polte. Indoors a BLE system can provide accuracy around a meter; for centimeter-level accuracy the system would need UWB.
Along with the communication link, the method of determining location can constrain accuracy. A simple proximity measure (signal strength) can provide three meters or so in location accuracy. Using angle of arrival and triangulation from multiple beacons can offer a meter or less. For sub-meter accuracy, developers will need to use ranging based on time-of-flight or time-distance of arrival information from multiple beacons.
Figure 2 Indoor asset tracking design will vary depending on the location accuracy the application requires, which can range from a meter or two to a just few centimeters. Source: LinkLabs
Most assets to be tracked do not have access to power, so the IoT device will need to be battery-powered. The device’s operating lifetime thus will primarily depend on the battery life, and the longer the better. No user wants to replace hundreds to thousands of batteries with any frequency.
Numerous factors affect battery life. The type of communications link involved, of course, is a key factor in determining how much power is required to provide a location update. But equally important are factors such as the time required to provide a location update, the power consumed when the device is in a steady state condition between updates, and the frequency of such updates. Application requirements can affect this last factor, but it is often available for the developer to use in “tuning” the battery life.
Developers will need to think beyond the tracking device itself to also consider the design’s impact on backhaul requirements. A tracking device that simply makes ranging measurements from beacons, for instance, and then sends the raw measurements to the network for location processing, imposes a much greater burden on the network than a system that extracts its location first and sends only the result. Similarly, a device that regularly broadcasts its location creates a greater burden than one that only responds when queried. The amount of information sent to the network and the frequency of device transmission also affect backhaul requirements. Too much information too frequently can quickly limit the scale a tracking system’s installation can effectively reach.
The cost of an asset tracking system ultimately determines what applications it can effectively serve. High-value assets such as vaccine shipments can more easily justify an expensive system. The lower the total system cost, however, the greater the range of applications it can serve and the greater the market size for the tracking devices themselves.
There are two types of cost to consider. One, of course, is the device cost. It makes no sense to help avoid lost inventory by using a $100 tracking device on, say, a six-pack of beer — but a $1 device may be justifiable.
The second type of cost to consider is the system cost, including the backhaul infrastructure required. Even if the tracking devices themselves are relatively inexpensive, the cost of network infrastructure, data fees, or cloud resources needed can limit the practical size an asset tracking system can support.
With these factors as a starting point for design consideration, developers seeking to create an asset tracking system will create a solid foundation for their design’s marketability. For users of asset tracking systems, these considerations will help them identify the system that will best meet their needs.
This article was originally published on EDN.
Rich Quinnell is a retired engineer and writer, and former Editor-in-Chief at EDN.
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