Man-Machine Interface in Material Handling
As employees are asked to
work smarter, how they interact with automated and manual equipment becomes
increasingly challenging and important.
by Clyde E. Witt, executive editor,
and Leslie Langnau, senior technical editor
Any point where an operator works with a piece of material
handling equipment is an interface.
Ergonomics is at the center of this interface, often
intertwined with other functions such as equipment design, expectations and
performance. Along with the positioning of equipment for greater operator
comfort and productivity, and terminal screen visibility, other areas
attracting attention are information access and noise.
While much is being done to make it easier for people to
work with the material handling equipment in place, more can and needs to be
done. The trend Material Handling Management editors see is an emphasis on
improving self-sufficiency in the relationship between human and machine.
In this article we’ll look at how safety and ergonomics
have affected the design and function of products within several segments of
the material handling industry.
Health and safety
The workplace can be dangerous. Not as dangerous as your
home where most accidents happen, but dangerous in terms of injuries that can
occur in the routine of doing business. And the injuries can be costly in
financial terms.
Keeping the worker out of harm’s way has become an
ergonomic issue as well as a safety issue. For example, as Keith Kersten,
product supervisor, information platforms, Rockwell Automation, says,
traditional operator interface terminals are panel-mounted, constraining the
operator by their mounted locations. “New portable technologies include
cabled and wireless tools to help manufacturers minimize mishaps and enhance
protection against injury,” says Kersten.
Data flow
There’s been progress in helping machines work better
with operators, but problems persist. Overall, these problems have a common
cause — not taking full advantage of the features vendors incorporate
into equipment. This issue is most noticeable with software.
The latest trend with computer systems and operator screens
— traditional interfaces between human and machine — is to make
information and functions available on the Web. Such data are available on the
smallest pieces of equipment, like personal data assistants. The goal is to
give everyone a “heads-up” that a problem might be developing and
the opportunity to do something about it before serious delays occur.
The benefit is the ability to analyze conditions and adjust
them quickly. It gives employees a proactive rather than reactive capability,
and thus enhances self-sufficiency. At United Parcel Service (UPS), for
example, operators use this capability to keep sortation systems flowing
smoothly. Many UPS facilities have back-up sortation systems for various
package destinations. If one system gets bogged down, operators can quickly
divert packages to the back-up, ensuring product throughput.
Diagnostics software and functions are following a similar
path. Vendors are making it easier to access diagnostic data and then use that
information to solve problems. “Design engineers are making diagnostics
obvious to everyone, not just to other engineers,” says Mike Kotecki,
senior vice president, material handling integration, HK Systems.
Therefore, a lot of data on material flow processes are more
readily available. However, whether anyone is doing anything with those data is
another question. In many companies, the data are stored in databases rather
than used to make improvements to the system. This is one of those features
that companies aren’t taking advantage of.
Designing data collection devices
We’ve made a lot of strides since the first computer,
ENIAC (Electronic Numerical Integrator Analyzer and Computer), came on the
scene in 1943. It was the size of a tractor-trailer rig and couldn’t do
functions we find in wristwatches today.
Because most automatic data collection equipment grew up in
an era of ergonomic consciousness, design of this equipment has generally been
good. However, as the drive to give terminals more functionality was happening
at the same time terminals were being miniaturized, some ergonomic factors were
overlooked. Small keys and buttons on lift truck-mounted terminals didn’t
work for operators wearing gloves. Hand-held scanners became awkward and were
referred to as a brick on a stick. Intermec, like several other companies,
recently introduced its Model 2435 hand-held data collection terminal. “Our
customers told us they needed a larger display in an easy-to-use ergonomic
design,” says Jeff Hovorka, Intermec product manager. Among the
unit’s many features are keypad buttons that are larger and more widely
spaced than other industrial terminals for workers wearing gloves.
When creating a data collection device, designers consider a
host of variables such as the environment the scanner may be used in, degree of
ruggedness desired by the user, lighting conditions, size of the person using
the scanner, and types of tasks the user may encounter.
Often the approach to product design is to ask the customer
about intended use. The components of the actual product, such as a bar code
label scanner, often follow how it’s used. Thus, the research lab for
many data collection devices becomes the customer. For example, if these
devices are to be used by truck drivers, a major design element would be to
eliminate frequent wrist movements required for scanning and viewing data. A
more natural viewing angle of 35 degrees is built into the device.
Ergonomics has a major impact on productivity. How a tool
feels and looks makes a difference in the field. Companies often have a medical
council to sign off on the design of a product before it goes to market. Symbol
Technologies, like other firms, also has a user interaction group that aids in
the design of products.
Symbol’s wearable ring scanner is an example of how
ergonomic design helped make breakthroughs for scanning technology. The small,
wearable scanner offers hands-free order selection, ideal for short-range use
and selecting items from conveyors or totes. The unobtrusive mobility of the
unit optimizes handling-intensive applications.
One size fits nobody
Since a single data collection device might be used by
several operators, flexibility is also a concern. The way manufacturers get
around some of these flexibility issues is through software. They can program
different buttons to function as the “enter” key. Also, designating
specific function keys on a unit is a way to streamline the unit and make it
easier to use. Often there are functions that require the operator to hit the
same two (or more) keys in the same sequence. Through software, a single key
can be designated so that when pressed only once, it performs this same
multi-key function. It means fewer key strokes for the operator and less chance
for error.
The Golden Zone
Picking is an area where operators closely interface with
material handling equipment. The ergonomics of picking systems plays a crucial
role in the human-machine interface. One of the more effective methods for
improving this interface is to keep things simple. It’s crucial to
examine employee capabilities and use a system that can work with, rather than
against, them.
Some vendors, for example, offer systems that accommodate
various physical sizes and strengths of employees. Software changes raise or
lower specific handling components to different heights. Power-assist devices
help lift and move heavy (by the employee’s definition) loads. Conveyors
also do a good job of keeping weight at reasonable levels. And flow racks bring
parts to the operator, demonstrating the continuing trend of bringing work to
employees to minimize steps.
Instructions for employees, such as what to pick and how much,
are available in several interface forms, from pick-to-light, paper and
personal data assistants (PDAs). Pick-to-light systems offer quick, simple
instruction in fast-paced applications where items are brought to the operator.
PDAs can be useful in environments were operators must walk or drive around to
find items.
Which systems are chosen can be an issue, though, for the
workforce. Some employees are more comfortable receiving explicit instructions.
Others don’t mind when their decision-making comes into play. And pick
lists should at least be highly readable to reduce the chance of errors.
Profiling is crucial in picking systems because it shows
which items are moving faster. Unfortunately, it’s not done enough.
“Lack of profiling is costing companies money big time,” says Tom
Lagaly, vice president, FKI Logistex — Real Time Solutions. Profiling
should be done at least every couple of weeks, maybe more depending on stock
turns. Fairly easy-to-use software is available to make this task easier. For
optimum efficiency, 94 percent of the faster-moving items should be in the
“Golden Zone,” the area from an operator’s waist to
mid-chest.
Containers by design
Reusable containers and pallets are designed to enhance the
life of the equipment as well as operator ease and safety. As Bret Carlson,
Orbis, says, “Ergonomic handles and collapsing sidewalls, combined with
lifting and tilting tables, reduce injuries and improve productivity.”
As reusable containers gained in popularity, designers
improved the physical attributes of the product. The less-quantifiable benefits
that many users intuitively anticipated have also been proven.
The elimination of box cutters, staples, loose trash and
broken pallets has reduced injuries. Users note that improved housekeeping and
employee morale parallel reduced workers’ compensation claims.
According to Dr. Joy Ebben, an expert in work-related
cumulative trauma disorders and workplace design, one way to approach
justification of ergonomic improvements is to convert workers’
compensation-related expenses into products made.
“An estimation is that for mid-size manufacturing
companies that make about five percent profit, they must sell $4 million worth
of additional product to cover $200,000 in injury and illness costs,” explains
Ebben.
Listen up
The current interest and growth of voice data collection
systems are in part due to ergonomic concerns. Typically, in a warehouse
picking environment, workers have a difficult time performing their tasks while
simultaneously retrieving and entering computer information. Their ability to
do the job they are hired for — picking — is hindered by having to
manage paper or hand-held devices. One of the challenges of former
voice-directed systems, or any speaker-dependent system, was limited
vocabulary. The user had to read a list of words into the system so that the
computer would recognize that voice the next time the operator logged on.
Speaker-dependent systems must adjust to each particular operator wearing the
headset.
A breakthrough by SyVox with its speaker-independent
technology goes beyond the ability of the computer to recognize a single voice,
to the point where it can recognize anyone’s voice. This technology is
accurate with people whose speech exhibits foreign or regional accents and with
people whose voice is temporarily altered by stress or a cold.
Workers, with the combination of wearable speech data
terminals and an RF network, can keep their hands and eyes focused on the job
while at the same time accessing and entering data with their voices.
The system is as simple as hearing instructions through the
headset, doing the task, then speaking data and instructions back to the
computer through the headset microphone. The system requires no knowledge of
computers.
The lightweight hardware the user wears communicates with
the enterprise warehouse management system for the enterprise resource planning
system to receive and process instructions, to provide real-time information
for effective resource management and to monitor the performance of the
processes throughout the warehouse.
Quiet, please
Material handling equipment is inherently noisy. Put a
number of machines in an area, and the sound levels can be literally deafening.
But there’s an added twist. Fulfillment demands are increasing noise
levels. To reach higher throughput and productivity, managers must install
additional equipment or have operators run existing equipment faster. Both
solutions raise the noise level.
Too much noise prevents operators from hearing alarms or
warnings. An alarm signaling a bottleneck on a conveyor is one thing, but an
unheard alarm from a lift truck backing up can have serious consequences.
Noise is a factor in employee retention, too. During the
last few years, machine builders and companies have worked to reduce noise
levels. Several vendors report that customers increasingly request a new piece
of equipment fit into an environment where the total noise level is less than
75 dB. (OSHA limits noise exposure to 90 dB over an eight-hour period.)
Sometimes noise issues are resolved simply by moving
equipment away from other noisy systems, or away from portions of the facility
that reflect and enhance noise. Vendors, though, are incorporating several
solutions aimed at eliminating vibration, the main source of noise.
For example, some solutions use better material and designs
to more firmly hold axial rollers in conveyor frames to dampen chattering.
Other solutions involve adding noise-absorbing material within the machine
construction. 3M offers a product that turns vibration into heat, which can
then be dissipated, removing a lot of noise from a system. Acoustic foam placed
between metal parts that may rub together is another solution.
Systems with belts can trap air between the belt and nearby
components, creating a humming noise. New designs allow the trapped air to
escape.
A byproduct of all the noise-reduction effort is better
material handling equipment. By reducing vibration, there’s less wear and
tear, so systems last longer and perform better.
Modifying the environment is often a last resort. But
companies can install noise-absorption panels to walls and ceilings, change the
flooring, and make other changes to the building itself.
It’s electric
More material handling systems are moving to electric power
rather than pneumatic and hydraulic power. “Electric systems have
improved their reliability to the point where they are a viable alternative to
more traditional [pneumatic and hydraulic] power methods,” says Wes
Paisley, president, Dearborn Mid-West Conveyor Company. They also offer
advantages in cost and maintenance.
In addition, they work well with software commands that
change their position (up, down, right, left, etc.) or speed. Adjustable
material handling equipment, such as lift tables and skillet conveyors, are
examples.
Smarter and safer
Ergonomics is the key to creating smarter workers and safer
workplaces. Using voice-directed automatic data collection systems, workers
have a greater awareness of their surroundings. Unencumbered by paper or
hand-held devices, they are not distracted and can watch for lift trucks or low
racks where they might bump their heads.
Monitoring the control of a machine or process from a spot
off the production floor, they no longer have to try to read computer displays
in less-than-ideal light conditions or struggle to push small buttons while
wearing gloves.
These examples of workplace improvements through ergonomics
will not only make the worker smarter, they will make the worker more self
sufficient. MHM
Simulate the Human/Machine Interface
The human/machine interface must not only prove productive,
it must be ergonomically correct as well. Object-oriented simulation tools
allow you to populate your facility model with scaleable human figures and
assess their ergonomic fit. It’s possible to input the work environment
you’re simulating, add motion and cycle-time data and validate
assumptions you’ve made or programs you’ve designed.
When creating a factory or distribution center you need to
do more than design the facility. The creative process requires analysis and
emulation of complex systems. Simulation programs offer templates of commonly
used components in facilities for quick and accurate modeling for a wide range
of systems. Using visual tools makes it easier to take ideas and programs to
management as well as to communicate with your staff what changes are required.
Managing complexity and determining the optimal
configuration of equipment require visibility of all the variables whether your
business is e-commerce or automobile manufacturing. Using simulation to design
and analyze your facility can save money when it comes time to purchase
equipment. Having too much equipment can be as detrimental as not having
enough, to say nothing of having the wrong machinery.
Another area where simulation is being used is in
retrofitting or analyzing existing systems. Troubleshooting and identifying
bottlenecks along the line with a simulation program is a lower-cost method for
experimenting with different designs to test effects on throughput.
There are a host of simulation products available, such as
the AutoMod Suite from Brooks Automation, that can help you do the job.
Sources
For detailed information on equipment mentioned in this
article, visit mhmanagement.com, or the following sources:
Buckhorn, buckhorninc.com
Dearborn Mid-West Conveyor Company, dmwcc.com
FKI Logistex, fkilogistex.com
Hand Held Products, handheld.com
HK Systems, hksystems.com
Intermec Technologies, intermec.com
LXE, lxe.com
Orbis, orbis-menasha.com
PSC, pscnet.com
Psion Teklogix, psionteklogix.com
Rockwell Automation, automation.rockwell.com
Swisslog, swisslog.com
Symbol Technologies, symbol.com
SyVox, syvox.com
Vocollect, vocollect.com
Voxware, voxware.com
