Man/Machine Interface in Material Handling

Nov. 1, 2001
How workers interact with automated and manual material handling equipment is a big factor for working smart in an increasingly challenging world.

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.


For detailed information on equipment mentioned in this article, visit, or the following sources:


Dearborn Mid-West Conveyor Company,

FKI Logistex,

Hand Held Products,

HK Systems,

Intermec Technologies,




Psion Teklogix,

Rockwell Automation,


Symbol Technologies,




Latest from Labor Management

Ways to Attract  and Retrain Supply Chain Talent
ID 248887758 © Timon Schneider |