Industrial Robots in Warehousing and Distribution Operations
The warehousing and distribution industry is
facing new challenges due to the increasing number of SKUs coupled with the
need to provide more “direct-to-store” pallets. This need is causing
disruption in an industry where product handling, depalletizing, and palletizing
are typically done manually. Having a large number of SKUs and having to supply
“direct-to-store” pallets requires an increase in labor, an increase
in the quality of the labor, and is a physically demanding job. These new
requirements also cause the distributor increased costs due to product damage
and fines/penalties in shipping inaccuracies. To combat this, applying robots
to key functions in the warehouse and distribution centers is needed now.
FANUC America has successfully implemented robotic depalletizing and
palletizing systems since 1982. Traditionally, these palletizing/depalletizing
robots have been used in the food and consumer goods manufacturing arena for
homogenous palletizing applications, such as building a pallet at the end
of a production line with only one type of product on the pallet. But the
warehousing and distribution arena often involves build-to-order custom pallets
mixed with multiple SKUs, potentially of widely varying sizes and exterior
One major challenge to automating this process with
a robot is mimicking the high-level decision process that human operators
make with each placement of an item on the load, as they carefully fit each
one to achieve the highest shipping density combined with pallet load stability
and minimal product damage.
Another significant challenge is emulating the
broad range of adjustability inherent in a pair of human hands. In the past
10 years, great strides in development of intelligent robots, software and
tooling have been made to enable robots to meet the needs of the warehousing
and distribution market for building these mixed unit load pallets. FANUC
Robotics has focused our developments for the warehousing arena on the Receiving/Replenishment
and Order Fulfillment/Shipping areas. These are prime target areas where robots
can provide a considerable benefit.
In the Receiving/Replenishment areas of a warehouse, robotic layer handling
is employed to break down homogeneous pallets and either build mixed layer
pallets (to go to shipping and be sent directly to stores) or to place a layer
of product to a singulator to transport individual items to storage (for subsequent
delivery to a palletizing operation in Order Replenishment / Shipping). In
the Order Replenishment /Shipping areas, the robots palletize “direct-to-store”
pallets, usually involving Mixed Item Palletizing (MIP). Building a “direct-to-store”
pallet normally consists of multiple SKUs on a pallet, and potentially, orders
for multiple stores on the same pallet. Note that Mixed Item Palletizing (MIP)
is a generic naming convention. This type of application is often times referred
to as Mixed Case Palletizing (MCP), Mixed Load Palletizing (MLP), and Random
Order Palletizing (ROP). Beware that there may be subtle differences, so you
will need to investigate the user requirements and the available application
solutions on the market to ensure you have what you need.
Layer handling is a straightforward process and a relatively simple
application for an industrial robot. It involves a robot equipped with layer
handling tooling to accommodate the various products to be handled. Simplified
robot programming enables the robot to either build mixed layer pallets or
place a layer to a singulator. The mixed item palletizing operation to create
“direct-to-store” pallets is considerably more complex, but is
the largest robotic opportunity to solve the problems facing the industry
such as eliminating the notoriously bad ergonomic issues of manual palletizing,
reducing product damage, and improving order accuracy.
Before we discuss robotic mixed item palletizing and the associated
state-of-the-art technology, we need to define a “good pallet.”
In our investigation of warehousing requirements, a good “direct-to-store”
pallet has the following attributes:
These attributes must be weighted and prioritized according to:
The industry targeted (beverage, grocery, consumer products,
The product being handled (cases, shrink-wrapped bundles,
The transport system after the pallet build operation - oftentimes,
direct fork truck handling.
Specific characteristics of the industry, product, and transport system
will determine the correct combination and order of the build attributes in
order for a successful system. One of the largest factors is conveyability.
What Makes a Pallet Conveyable?
Simply put, a pallet of product must have the ability to withstand the
forces applied to it when it moves. This movement may be via a transport system
(i.e., conveyor) to a stretch-wrapper or via a fork truck either to a stretch-wrapper
or directly to a truck. In building a pallet, a mixed item palletizing (MIP)
algorithm must take into account forces due to acceleration and deceleration
of the pallet. The three basic pallet building principals are
Center of Gravity
MIP algorithms must analyze the pallet build and take these principles
into consideration. The algorithm must be flexible enough to modify the build
pattern to maximize the pallet build attributes desired. The MIP algorithm
considers the stability of the resultant stack prior to placing each and every
item. If stability of the pallet is deemed lower than the configured minimum,
no other items are stacked on the pallet and a request is sent for a new pallet.
Creative solutions often optimize the entire system and allow for higher
pallet builds. However, be careful to ensure that pallets built for optimal
height and density do not sacrifice the overall stability and make the load
impossible to transport. In addition, end user requirements must be considered.
For example, when a build-to-order pallet arrives at a store and the stretchwrap
is cut away: will the built pallet collapse and items fall to the floor? This
could be a showstopper, but potentially could be avoided if stability is taken
into account while the pallet is being built.
Mixed Item Palletizing Operational Modes
Automating the Mixed Item Palletizing (MIP) operation is extremely important
to warehousing and distribution centers; this is the area that has the largest
labor costs, greatest potential for product damage and where order inaccuracies
from manual labor are most prevalent. This is where distributors will get
the largest return on investment by automating with robots.
MIP automation demands an understanding of two fundamental operational
modes that can be implemented. The two operational modes are:
In a preplanned mode, customer order data is analyzed well before the
order is processed. The various SKU items in the order (perhaps multiple
orders) are then picked, sequenced and delivered to the robot based on the
results of the preplanning algorithm that defines optimal pallet build solutions.
MIP workcell(s) then palletize the variety of SKU items in the customer order(s).
Note that an MIP workcell is an island of automation usually consisting of
a robot with its end-of-arm-tooling to handle the product, safety fencing
surrounding the robot area, infeed conveyors (bringing in product), and outfeed
conveyors (sending out mixed item pallet builds).
There are many algorithms on the market that can preplan for manual
operations. For robotic building, the list of available algorithms is shorter
since the preplanned build must consider the robot’s capabilities in
terms of reach, robot tooling, and ability to place the product on the pallet
when considering limitations of neighboring products and peripheral obstructions.
All of these aspects must be considered by a preplanning algorithm to have
a successful operation.
The Real-Time mode is where the MIP workcell(s) must determine the best
location on a pallet for a variety of SKU items at the moment they are delivered
to the robot. While doing this operation in Real-Time, the algorithm must
also consider the robot’s capabilities in terms of reach, robot tooling,
and ability to place the product on the pallet when considering limitations
of neighboring products and peripheral obstructions This Real-Time mode is
often referred to as a Random Order mode.
What Comprises a Mixed Item Palletizing Workcell?
As mentioned earlier, the robotic workcell is an island of automation, with an infeed conveyor (for product coming into the workcell) and an outfeed
conveyor (for built mixed case pallets). There are three critical components
of the workcell that must be carefully selected:
The robots handle the products to the build pallet. The robots can be
“stand-alone” robots or they can be mounted on robot transport
units (RTU) and move between build pallets to allow for multiple build positions.
The EOATs handle products of different sizes, shapes and textures. The
EOATs must be extremely reliable and able to pick a wide variety of SKUs.
They must also impose minimal restrictions on MIP algorithm(s) - tooling
restrictions will limit pallet build options and compromise the quality of
the finished load.
The software is the brain of the operation: it determines the best
pallet build scenario and directs the robot, with its EOAT, to place each
product to the proper location on the pallet. The software must be able to
build dense and stable pallets. In the real world, the software must also
be intelligent to handle events that go wrong. For example, in a preplanned
mode when product arrives at the robot out of sequence, the software must
be able to handle the “Broken Play” by determining what has gone
wrong and how best to continue placing product on the pallet. FANUC America’
Mixed Case Palletizing (MCP) Software Suite has the capability to switch automatically
between a Preplanned mode and a Real-Time mode. Without this capability, manual
labor must intervene to complete the build, leaving the door open for product
damage and order inaccuracies.
Mixed Item Palletizing Software
FANUC America offers a Mixed Case Palletizing (MCP) Software Suite that provides for a Preplanned mode (whether it is a FANUC Preplanned algorithm
or a third-party algorithm) and for a Real-Time Mode. There are many features
of the software suite that are needed for any MIP application:
Ability to handle multiple Preplanning algorithms: choose
the best algorithm for your application. Beverage, grocery, and general merchandise
are three different industries where the pallet build attributes are different
and may require a different preplanning algorithm to provide for the best
MIP pallet build. Note that if your SKU content (aka, size variation) is small,
a preplanning algorithm may not be needed.
Ability to control the functions of the robot and its tooling:
the tooling needs to be flexible to accommodate the wide variety of products;
therefore, the software must be able to control the many functions of the
tooling that may be needed to do this. This may include control of servo-motion
tooling that optimizes the size of the tooling for the appropriate size of
the item to be handled, thus reducing pallet build time and increasing handling
reliability (squeeze to a size and force).
Ability to interface to the robot’s surroundings.
Ability to monitor (Monitor Function) and report (Reporting
Function) what is being built and what has been built in order to track and
verify order accuracy
These are the run-time aspects of the software, but there are other
operational aspects needed to predict if a pallet can be built optimally for
an order such as Virtual Pallet Build and Robot Simulation.
Virtual pallet processing determines the viability of the pallet build before product is sent to the MIP workcell and provides
historical information after a pallet has been built, such as:
Virtual robotic palletizing with FANUC America’ ROBOGUIDE®
simulation software determines if a pallet can be built. The simulation automatically
generates the product sizes graphically and presents them to a virtual robotic
workcell where the robot (with the appropriate EOAT) handles
the product in the virtual world. The virtual simulation enables the robot
to verify the sequences: from the product pick up, to the approach points,
to the place points, to the away points, and finally back to the perch point
ready for the next product. In doing all of this, the ROBOGUIDE® virtual
simulation analyzes the robot’s reach and motion to ensure that the
pallet can be physically built.
Mixed Item Palletizing Software Versatility
In using a Preplanned operational mode, the product must arrive at the
robotic workcell in the sequence needed to build a pallet optimally. However,
sometimes products get out of sequence. The question arises: What do you do?
Most operations are forced to go to a manual mode and stack the products
by hand. This can be done by having a smart MIP software package that is virtually
stacking the pallet and can print out a pictorial (with product item list)
of what has been palletized and what remains to be palletized. FANUC America
has this feature built into its MCP Software Suite (it also indicates what
was stacked automatically and what needs to be stacked manually). Additionally,
our MCP Software Suite also incorporates a special feature called the “Broken
Play” option. FANUC America’ Real-Time algorithm is how to handle
the “Broken Play”, by automatically taking control and palletizing
whatever is presented to the robot to the best available position on the pallet!
This “Broken Play” option is unique to FANUC America’ MCP
Software Suite and will help increase uptime, reduce product damage and order
inaccuracies since the human element is not introduced.
Schematically, the FANUC America’ MCP Software Suite operates
as shown in the following flowchart:
How does the patented MCP Real-Time algorithm work?
Evaluates a series of prioritized RULES to select and place
Each RULE covers a special condition (full layer, full region,
adjacent height, stability, supported area, interlocking, combined similar
product, combined space, etc.).
Remembers previous rule if appropriate (full layer will remember
Provides configurable process parameters (which rules to use,
pallet size, etc.)
Last rule is BEST SCORE
Evaluates each case available against every potential position
on the pallet
Uses 20 different evaluations: Supported area, stability,
size, adjacent height, etc.
Each evaluation is weighted or factored differently
Factors stability and supported area
Highest Score WINS!
How to Choose What Mixed Item Palletizing Software and Operational
Mode is Right for You
Understanding your product mix and typical customer orders is important
in determining the best solution for your operation. Pallet Optimization
software suppliers and Mixed Item Palletizing suppliers can evaluate your
product master list (SKU#, size, weight, etc.) and order data (orders for
a peak and average day; consisting of order number, SKU #, quantity per SKU,
etc.). These customer-specific attributes will allow these companies to determine
their best algorithm to use and validate what operational mode you need. If
product mix is low (physical size), the Real-Time algorithm may be your best
choice, since its price and complexity are low. If your product mix is high
(large physical size variations), the Preplanned algorithm with “Broken
Play” may be the answer, but the associated costs and system complexity
The Comparison Matrix below will give you a guide in the choices on
the market. The matrix also illustrates key pallet build requirements you
may have versus cost and complexity.
Warehousing and distribution centers are facing ever increasing customer
demands for higher product mix, higher variety of products for each order,
multiple store orders on the same pallet, aisle rules, and an unforgiving
demand for accurate orders. To face this challenge, automating the warehouse
and the use of robotic applications at key points in the warehouse are a necessity.
You are not alone — all warehousing and distribution centers are
facing the same battles. The first companies to automate will be able to overcome
the ever increasing costs associated with high labor content, an inconsistent
labor pool, product damage, order inaccuracies, theft/security, and increased
In the past, there were very few choices for automation and greater
limitations regarding which warehouse operations could be automated. The advancement
in intelligent robotics has broken the barrier, making it affordable now.
The choices, once limited, are now wide and far-reaching. At FANUC America,
we have developed software and hardware tools to enable customers and system
integrators to tackle this formidable task. The MCP Software suite, available
through FANUC America, can allow you to choose the best robot, the best algorithm
to meet your needs (either FANUC America’ algorithm or a third-party
algorithm), and the best End Of Arm Tooling to allow you to build mixed item
Field-proven Mixed Item Palletizing solutions are now available:
Real time: smaller investment, good performance
Preplanned: larger investment, better performance
Preplanned + Real time = optimal solution --- Only available
through FANUC America
The warehouse/logistics market presents a significant new opportunity
to software and hardware suppliers, so the costs and complexity will decrease
over the next few years making affordability more enticing. The United States
has started adding robots to warehousing and distribution centers only within
the last 10 years (but concentrating implementation in only the last 3-5 years).
However, US industry is beginning to implement mixed item palletizing at an
 D. DeMotte, M. Poma, and A. Monique. United States Patent: AUTOMATED
PALLETIZING CASES HAVING MIXED SIZES AND SHAPES, US Patent # US 7,266,422