How accurate should your asset tracking system be?

Date: May 14, 2019

‘How much accuracy can we expect?’ is often the first question we are asked by our clients while discussing RTLS technologies. Accuracy has become less of a concern due to the emergence of UWB, as it can offer an accuracy in the range of 5-20cm.

Some healthcare-specific use-cases demand an accuracy of 1-2cm. These use-cases are mostly diagnostic related and have to do with optimizations. Whether such use-cases come under the purview of RTLS or not is still a matter of discussion.

However, not all the use-cases require cm-level accuracy; in fact, precision might turn out to be overkill for these kinds of use-cases. In this article, we shall explore some of the popular RTLS use-cases and categorise them into requiring either ‘Room-level’ or ‘Shelf-level’ accuracy.

Room-level accuracy – This categorises the use-cases for which cm-level accuracy is not required. For instance, take the case of locating a machine in a hospital. For a hospital staff, knowing in which room a machine is located is enough, so the knowledge of the exact point in the room is not important. In, such use-cases, BLE might be a suitable option, as a few meters of accuracy would do just fine.

In most of these use-cases, 2D coordinates are required, and that minimizes the overall requirements (for instance, the no. of anchors required) to a great degree.

For more details on the Indoor Positioning market, Have a look at our infographic.

Some other use-cases that fall into this category are –

  1. Consumer Luggage Tracking – Informing the passenger of the whereabouts of the luggage, for instance, when is it boarded, when it’s at the carousel, etc. This need not have cm-level accuracy. The passenger getting the information 1m later won’t be a grave issue.
  2. Kids & Elderly monitoring – Kids and elderly can be given a trackable wearable device. The wearable would have fall detection, a panic button, geofencing and geolocation. The data is shared with family members and relevant services. In this case, knowledge of the room location is more than enough to take action.
  3. Trolley Tracking – Locating and managing the luggage and shopping trolleys in airports and shopping malls, respectively, to organize the fleet of luggage and trolleys. Presenting trolleys to customers at the right time and place can be a big boost to the customer satisfaction. Again, in such situations, cm level of accuracy would prove to be unnecessary. Trolley tracking can also bring to light the need for retrieval and redistribution of trolleys. This would also help in keeping tracking of the usage of the trolleys.
  4. Agriculture – Gathering real-time information about location, speed, body temperature and stress levels of livestock. Reduce inefficiencies, decrease operating costs and improve the health and safety of cattle, horses, sheep and goats.
  5. Construction sites – In this case too, cm-level accuracy is not necessary, as knowledge of the vicinity alone would be helpful. Other than objects, people tracking is also important in construction sites in order to reduce risks, elevate safety and improve performance.
  6. Laboratory equipment tracking – This case can be understood in line with hospital equipment tracking.

While ‘precision’ and ‘accuracy’ are of vital significance when it comes to real-time location tracking, it’s not the only metric to judge the value of a solution. Cost, ease of implementation, form factor, and power efficiency are other factors that must be taken into consideration while choosing the asset tracking system.

 

Shelf level accuracy – Some applications exist in which pin-point accuracy cannot be compromised, and thus a tracking system would lose its purpose if not able to deliver that. Automated warehouses can be cited as one such case where cm-level accuracy is needed, so Ultra-wideband might be the answer here.

When shelf-level accuracy is needed, 3D coordinates are usually required. That again necessitates the use of UWB technology.

 “FCC first opened up the ultra-wideband (UWB) radio spectrum for unlicensed commercial use in 2005.”

For more details on the advantages of using UWB-based solutions, take a look at Advantages of using Ultra Wideband (UWB) technology for Indoor Positioning.

Some of the popular use-cases requiring self-level accuracy -

  1. Inventory Management – Inside a large warehouse, there are a huge number of goods that are required to be stored and transported internally. Even after keeping manual records of the placement and movement of all the goods, errors in detecting them and subsequent delays are palpable. Such delays can prove to be very costly to the warehouses. With a precise asset tracking solution in place, the location of the goods can be easily seen and noted, which would ultimately save time from searching.
    Let’s take the example of Amazon, which has a huge warehouse filled with millions of items. Easy localization of items by the employees is an important aspect of profitability for such companies.
  2. Pallet Tracking – In order to manage the fleet of pallets, monitoring pallet usage and retrieving them at right time is important. This will also prevent their loss. Effective tracking systems will also enable monitoring the conditions of the goods occupying the pallets.
  3. Manufacturing plant – In manufacturing or industrial units where workers are required to maintain a minimum distance from certain machineries, geo-fencing using tracking systems can signal the machine to shut-down when a human presence is detected in the vicinity.

When precision is of vital importance, we always tend to shift toward Ultra-wideband-based solutions. However, if the concerned facility is already equipped with the appropriate type of Wi-fi infrastructure, shifting the entire system to a UWB-based one might not be a viable option.

Let’s have a look at comparing the accuracies of the popular technologies

 
 Wi-FIRFIDUWBBLE
ACCURACY5-10m>10m10cm1-5m
UPDATE RATE1HzDifferent for Active & Passive4-10Hz1Hz
RANGE40-50mDifferent for Active & Passive40-50m5-10m
ENERGY EFFICIENCYLess efficientLess efficientEfficientVery efficient
INTERFERENCEHighVery lowVery lowHigh
TRACKING DEVICESWi-Fi Access pointsReaders & TagsUWB TransceiversBeacons & Sensors
   

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