Chris Cacioppo, CTO and co-founder, 6 River Systems, explains how the company’s 6RS software effectively determines the perfect zone for each robot without operator intervention…
Ask any pick-and-pack warehouse operator: there are pros and cons for each of the picking methodologies they choose for their fulfilment operations. Zone picking is ideal for large operations where pickers travel long distances to complete an order, or for smaller sites with high order volumes where congestion is an issue.
However, a common challenge associated with zone picking is predicting where your pickers will need to be based on inventory slotting and the order pool at any particular moment. Incorrectly predicting zones results in overworking some pickers while others wait with nothing to do.
Armed with knowledge of this challenge, we tackled the question: what if you could reap the benefits of zone picking without the challenge of analysing inventory slotting, consumer demand and labour availability? The solution: dynamic zoning. First, let’s understand the methodology we consider behind using static zones within a warehouse.
Why are static zones used?
In order to meet cut off times and maintain profitability, there is a constant pressure to keep a fulfilment operation running efficiently. Enabling colleagues to spend more time picking products and less time walking from one place to another is an area ripe for optimisation.
Although collaborative mobile robots eliminate long, unnecessary walks to deliver and receive work, they do not remove walking between picks. One technique to alleviate unnecessary walking is to break the picking area into zones and assign pickers to stay within them. This can be especially effective if there are sparse picks over a large area.
What are the challenges of using static zones?
There are two interrelated problems that often cause zones to be less effective than operators hope: defining zone areas and labour balancing.
Zone areas are set with the intent to distribute work evenly and, ideally, put common clusters of work in one area. The problem is that it is extraordinarily difficult to predict commonly clustered SKUs. Order profiles are constantly changing over time – from season to season and even over the course of the day. We often see warehouses that have been broken into zones based on physical size and then rarely, if ever, adjusted again.
The second related problem is labour balancing. Over the course of a shift, an operator wants their pickers to spend as much time as possible actively picking rather than travelling from one pick to the next or, even worse, idle. So, when utilising a zone picking method, it’s best when the orders are evenly distributed across all zones so each colleague is engaged. Unfortunately, this rarely happens – there are often drastically different workloads across zones.
To mitigate this, managers need to monitor order volumes constantly and make adjustments to zone assignments on the fly. Although we have some operations that want to use zones, most of our operations decided that there were too many inefficiencies and overheads managing them to make them beneficial.
The solution: dynamic zones
Analysing customers’ needs, we have devised an innovative solution that reaps all of the benefits of traditional zones with none of the drawbacks. We call this dynamic zoning.
When a picker completes a pick and is preparing to travel to the next, 6 River Systems’ intelligent allocation system calculates how much time it will take for that picker to follow the robot to the next pick location.
In parallel it also calculates how long it would take the same picker to meet another, closer robot if one is available. If it ever takes less time to do this switch, the first robot will travel to its next pick location on its own, leaving the original picker to start working with the new, closer robot, thus saving walking time.
The first robot then meets the next available picker near its next pick location. This has exactly the same benefit as if a perfect zone was created for each individual order.
Working out ideal zone boundaries is no longer a problem; there are no fixed zone boundaries! The 6RS software effectively determines the perfect zone for each robot without any operator intervention.
There is no need for labour balancing – it is done automatically. With dynamic zones, there are never any pickers waiting for work. As soon as an associate completes work with a robot, it leaves for the new ‘zone’ and the associate can meet the next waiting robot. We have already determined there is one that is available for them.
For more information, contact Simon Jones, senior solutions executive, UK & Ireland, 6 River Systems, at sjones@6river.com.
This article originally appeared in the April 2021 issue of Robotics & Innovation Magazine
