How to test a live parcel sortation system that’s not live: The use of digital twins

Fully automated high-speed sortation systems are highly complex and expensive. It’s no wonder then that CEP companies need proof that their investments in these intelligent systems are feasible. How can a CEP professional determine the sortation capacity and performance of a new sortation system without going through the timely and costly process of physically testing it? The answer: use a digital twin. 

By Janne Walsted and Lars Guldager


The pressure on CEP companies to obtain the right system design

When investing in new sortation systems for today’s large, modern parcel distribution hubs, CEP operators need proof of design: they must be sure that they are investing in systems that can actually meet their business demands, as well as future operations.

So, how can a distribution hub be satisfied that a new system it is investing in can actually handle its parcel volumes and sort plans at the highest performance?

The CEP company could, of course, physically test the system and certainly, this is how testing has been performed. But physical testing poses a number of obvious problems for larger hubs:

  • The bigger and more complex the system, the more onerous (or impossible) the practicalities become to physically test it.
  • Physical tests are costly for the CEP company.
  • Physical tests are very time-consuming – it can take many physical runs before a CEP business can be satisfied a new system is ready and able to meet its particular business requirements.

Take the logistics of physically testing whether a system can handle 60,000 parcels per hour, for example. This would involve gathering and storing 60,000 parcels, making and printing 60,000 parcel labels, marking the parcels and having trained and experienced staff to handle the parcels in order to get an accurate picture of system performance.

By using a digital twin to test a system, the hub is relieved of this enormous logistical effort, time and money.

What is a digital twin?

But what is it we’re actually talking about when we suggest using a digital twin?

A digital twin is a digital replica or digital overlay of a physical asset or operation. This digital representation or virtual model replicates the asset’s performance, allowing the creator of the digital twin to determine whether the asset — in this case, an automated sortation system — operates at high performance and where it can be improved.

The infrastructure behind a digital twin

A digital twin is a combination of two components: data and a representation of the given system. The representation can be two or three-dimensional, depending on the solution provider.

Data is collected and enriched and run through highly advanced visualisation software. The data adds a visual layer on top of the representation to make information relatable for the staff operating the system.

These layers, lifted from the data, could consist of information telling the system throughput, ‘no reads’, power consumption, and mechanical and electrical status. An extremely valuable feature of the digital twin is that it can be observed through various filters. CEP professionals can observe the entirety of their sortation systems while only focussing on capacity, for example.

Digital twins as proven technology: Their use in other industries

Digital twins are not new technology – they were invented by NASA in the 1990s – and have since been applied to great effect in other industries.

Digital twins have been used for many years now in the airport industry, for example. With airport baggage handling systems being so large and complicated, some form of digital modeling that could test software before it was implemented became necessary. Many airports have successfully used the digital twin technology to test baggage throughput and capacity.

What started as a means to train and test software, however, has led to wider applications of digital models. Airport operators have been using digital twins in their daily operations to achieve greater optimisation, detection of system anomalies and predictive maintenance. And as more and more data is added, it won’t be long before digital twins will be used to test even more variables such as catering flows or the transportation of luggage containers at the airport.

How digital twins can benefit CEP companies

The experience and knowledge gained through the airport sector’s application of digital twin technology stand to really benefit the CEP industry.

Digital twins can be invaluable tools for CEP professionals to test capacity and simulate production scenarios. By observing a digital twin, they can gain an overview and a good understanding of how an actual system and its processes will function in the physical world.

Typically, a systems provider assists the distribution centre in establishing the infrastructure that collects data from the sortation system, such as PLCs or sensors.  And even if the hub is a greenfield project and has yet to generate the data, it can perform its testing on computer-generated data. The provider processes the data and runs it through highly advanced visualisation software. The result is a digital twin – a version of the sortation system recreated in 3D.

When visualised in the model, all parcels/items and system elements are colour coded. Colours shift according to live status inside the system – for instance, which pre-sort line the parcel arrived from, whether it has passed an induction scanner in the sortation system, whether it is recirculating the system etc. All colour codes can be adjusted to match other supervision systems at the CEP facility.

Opportunities for testing

Once the digital twin is built, the CEP company can apply its sort plans to the system and test different variables, strategies and configurations. A digital twin can determine with a very high level of accuracy:

  • System capacity – including how it handles parcels coming in and parcels leaving the hub
  • System availability
  • System speed
  • The system’s ability to handle ‘no reads’
  • System performance on the number of shipments the hub receives
  • System performance under different operational conditions
  • The sustainability of the system in the future and its ability to handle changing parcel mixes
  • The number of operators needed in the system –depending on the time of the week/season (holidays, Black Friday etc)

For instance, a distribution hub may need to know how many items can enter a chute before changing a roller cage, a point at which the system has to be closed. A digital twin can model with precision the time in which the roller cage must be closed before being able to discharge items into the chute again.

CEP operations managers can gain these and many other insights by simulating multiple business strategies and watch how these strategies play out on screen – all without having to find items or resources to accurately test system throughputs.

As such, digital twins can be the perfect testing tools to help guide significant investment decisions.

Opportunities for system improvement in real time

Beyond the need to prove the design of a new parcel handling system, CEP operators can also deploy digital twins in daily operational scenarios to gain insights into how to optimise their systems at any given point in time.

With the visualisations of a digital twin, CEP managers can make on-the-fly adjustments to their sortation systems to improve throughput in real time and uncover the root cause of system errors without having to constantly monitor every part of the CEP business’ parcel operations.

In optimising how the available sortation capacity of the system is utilised, the digital twin can help minimise wasted capacity and optimise equipment and processes. It’s not uncommon for a CEP company to improve its throughput substantially after implementing a digital twin.


A digital twin is a very cost-effective means of accurately assessing whether a sortation system aligns with a CEP business’ requirements and operations when physical calculations are impractical or impossible to achieve. This proven technology can inform CEP professionals in their investment decisions, by being able to test with precision whether a system meets their business strategies. With these perfect testing tools, CEP operators can establish ‘true to reality’ representations without having to spend a dime.

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