On the basketball court, slam-dunks and last-second three-point shots usually make all the highlight shows. But, assists are a key stat that often gets overlooked.
On some assembly lines, today’s MVP is a robotic tool that was originally developed for use on the battlefield. It’s called an exoskeleton. The wearable device enables operators to perform a variety of overhead tasks. It minimizes physical strain and boosts efficiency.
Anyone who’s ever painted a ceiling knows how hard it is to perform any type of work over your head for more than a few seconds at a time. Imagine doing that hundreds or thousands of times during an 8- or 10-hour shift. Sooner or later, repetitive overhead motion will start to have a negative effect on arm, back, neck and shoulder joints and muscles.
Exoskeletons were originally developed for military applications. But, the technology is now being used on assembly lines by manufacturers such as Audi, Boeing, BMW and Ford Motor Co. Upper-body exoskeletons elevate and support an assembler’s arms.
Ford recently concluded a trial at its assembly plants in Flat Rock, MI, and Wayne, MI. Boeing also just wrapped up a six-month exoskeleton test at its plants in Charleston, SC; Renton, WA; and St. Louis. The tests proved successful and both companies are planning further investments in the technology.
“Exoskeletons are becoming increasingly popular with manufacturers,” says Christy Lotz, managing consultant at Humantech Inc., an ergonomics consulting firm. “They can generate a 30 percent to 40 percent reduction in muscle activity, so the chance of injuries and musculoskeletal disorders is reduced.”
Nonpowered exoskeletons offer protection and support against fatigue and injury by reducing the stress and strain of high-frequency, long-duration activities that can take a toll on the body over time.
Workers engaged in repetitive overhead production tasks run a high risk of being injured or developing long-term health problems. Awkward postures, overexertion and unsupported positions that stretch physical limits can result in compression of the nerves and irritation of tendons.
“On a typical automotive chassis assembly line, there are multiple tasks that require people to reach above their heads,” says Lotz. “That can translate to more than 3,000 repetitions per shift. As a result, blood flow is a big part of neck, shoulder and wrist injuries. We especially tend to see more injuries when people are new or less experienced.”
The physical demands of repetitive overhead work can take a toll on workers. Some operators lift their arms an average of 4,600 times per day or about 1 million times per year, greatly increasing the possibility of fatigue and injury.
As the working population continues to age, upper extremity ergonomic risk factors are increasing. Employers are suffering from lost productivity time, increased workers’ compensation claims and higher insurance premiums.
“Muscle capacity decreases over time as people age,” says Lotz. “Exoskeletons are beneficial, because they enable people to work at a lower percentage of their overall max.”
Shoulder injuries tend to be particularly difficult to recover from, and more expensive to treat, than other types of repetitive motion risks encountered on assembly lines.
“Backs and shoulders get injured the most, due to the biomechanics of the human body,” says Marty Smets, an ergonomics engineer at Ford who has been experimenting with exoskeleton technology for more than five years. “Very low or light forces at the hand can lead to high stresses at the shoulder. And, shoulders are one of the weakest joints in the body, because they have so much mobility.
“Shoulders typically cost an average of $30,000 to $60,000 to rehab and bring someone back to full functionality,” claims Smets. “An upper-body exoskeleton that costs $5,000 to $7,000 can provide a positive return on investment. If you buy 10 devices and prevent one injury, that’s a good deal.”
Although exoskeletons are new to assembly lines, the technology has been around for several decades. In fact, the first prototype was developed by General Electric Co. back in the mid-1960s. However, the bulky Hardiman was never commercially produced.
In the 1990s, engineers at the Defense Advanced Research Projects Agency (DARPA) picked up on the concept and developed exoskeletons for military applications. The technology has since been commercialized by defense contractors such as BAE Systems and Lockheed Martin. Devices such as the Human Universal Load Carrier exoskeleton enhance mobility and increase endurance on the battlefield.
Several companies have also developed robotic exoskeletons for medical rehab applications. For instance, Ekso Bionics Holdings Inc. markets the Ekso GT, which is designed to help treat people recovering from strokes or spinal cord injuries. It enables individuals to stand up and walk over ground with a full weight bearing, reciprocal gait in a clinical setting.
Lending a Lift
Ekso Bionics, a spinoff from research initially done at the University of California at Berkeley, recently entered the industrial arena with exoskeletons designed for use in the construction industry, in addition to automotive and aerospace assembly lines.
The company supplies Ford and other manufacturers with a device called the EksoVest. It strengthens the movement of the upper arms of people who have to carry out repetitive, overhead tasks. The lightweight, low-profile vest’s joints have an integrated mechanical spring support that gives arms greater strength.
Early versions of the EksoVest weighed 15 pounds. However, increased use of carbon-fiber composites and fabric mesh materials has enabled Ekso Bionics’ engineers to eliminate one-third of that weight.
The projected lifespan of the device is 5 million to 7 million cycles, which translates into somewhere between three to five years of everyday use on a typical automotive assembly line.
“The EksoVest provides 5 to 15 pounds of lift assistance to each arm to support a wide range of workers and applications,” says Zach Haas, industrial product manager at Ekso Bionics. “The biggest benefit of using upper-body exoskeletons on assembly lines is that workplaces experience increased endurance and reduced fatigue.
“Over time, the assistance provided by exoskeletons can lead to fewer on-site injuries, as well as some tasks being completed faster and with higher quality results,” explains Haas.
“The EksoVest is a passive exoskeleton with no electrical power,” adds Haas. “The lift support is supplied by the potential energy stored in gas springs that are installed in the actuators at each shoulder. We offer different springs that are set to different pressures which can be swapped out to achieve different levels of lift support to suit different applications and operator preferences.
“Our durable design has been thoroughly tested to withstand the wear and tear and harsh conditions of industrial environments,” claims Haas. “Removable soft goods allow customers to quickly adjust the size of the EksoVest to fit each worker and easily clean the vest to maintain good hygiene. It is made of various materials including aluminum, carbon fiber, steel and various synthetic fabric materials for the soft goods.”
According to Haas, the biggest misunderstanding that people have about upper-body exoskeletons is that they will make them stronger or enable them to lift more weight than they could before.
“Workers wearing an EksoVest should not be lifting more weight than they do without the device,” warns Haas. “It is designed to improve endurance for operators and reduce the amount of fatigue they experience over the course of the work day.
“[Assemblers] should continue to do their job as usual and expect to have more energy at the end of the day and be less likely to develop a long-term injury as a result of the assistance provided by the EksoVest,” says Haas.
Ekso Bionics, which is based in a former Ford factory overlooking San Francisco Bay, recently unveiled a lower-body exoskeleton called Artemis. The 13-pound device can offload up to 75 percent of a payload through the wearer’s load carriage.
Exoskeletons are available in either active or passive variants. The later are less expensive and complex, which make them more attractive to assembly line applications.
“Passive exoskeletons don’t have battery power, which can become complicated due to things such as recharging, heat and thermal management issues,” says Smets, who serves as a human systems and manufacturing virtualization technical expert in the advanced digital engineering department at Ford. “Batteries add extra weight to the system, in addition to actuators, sensors and wires.”
Passive exoskeletons are much simpler. They use a cylinder with a compressed spring in it. That applies force to a cam that enables the whole unit to work.
“While electrified, power-assisted suits get a lot of attention, they’re entirely different than what we’re using on our assembly lines,” Smets points out. “Those devices give the impression that you’re trying to add strength to what a person can do. That’s not what we’re going for with our exoskeleton applications.
“Our applications are more of an endurance thing,” explains Smets. “Operators are doing the same work that they did yesterday, but their muscles are now less fatigued at the end of the day.”
Exoskeletons on the Line
An upper-body passive exoskeleton only assists one joint—the shoulder. And, it only really helps when assemblers have their arms raised overhead; the rest of the time, they don’t feel any assistance.
“We don’t intend for the upper-body exoskeletons to be used for assembly tasks at normal working height (working with hands between waist and shoulder height),” says Smets. “That becomes more complicated to do passively, because more than one joint is involved.
“To get assistance from an exoskeleton between waist and shoulder height, you need assistance at the elbow and hip, in addition to the shoulder,” adds Smets. “When your hands and arms go up overhead, your body is at a distinctly different posture.”
Users experience weightlessness when they raise their arms over their head. The device kicks in and supplies force upward onto the arms. The shoulders are relaxed and supported.
Force is transferred from arm cuffs down through the exoskeleton’s spine posts and into the pelvis through a hip belt. The force is transferred from the pelvis down into the lower body.
“The pelvis has no muscles in it, but is an attachment site for many leg muscles,” says Smets. “The leg muscles activate to carry the extra load without detecting any extra discomfort.
“Because your legs are so strong compared to your shoulders, you don’t notice it,” explains Smets. “The extra force is not perceivable and does not fatigue you over the course of a day.
“The goal of an upper-body exoskeleton is to reduce the stress at your shoulder,” adds Smets. “Stress on joints generally applies to rotational forces or torques.
“If you hold a fastening tool above you, the weight of the device is driven into your body through the palms of your hands,” says Smets. “That causes a torque about your wrist that goes down your forearm and causes an equal and opposite torque around the elbow and into the shoulder.
“We primarily use pistol-grip and right-angle tools on our final assembly lines,” Smets points out. “Those types of tools are perfect for exoskeleton applications. But, the technology also has potential for use with other types of production tools, such as grinders and riveters.
“Pistol-grip tools cause a force that wants your arm to go down, but the exoskeleton applies a counter torque to keep your arm balanced and up,” explains Smets. “Shoulder muscles get a real benefit from that, because they’re not activated at the same level they would be if they had to support the entire tool weight.
“An exoskeleton provides lift assistance in the arm that’s holding the tool; it balances out the extra weight of the tool in one hand and the part in another hand,” says Smets. “Operators can set up the exoskeleton so that the arm that’s holding the tool experiences a slightly higher force than the other.”
Ford has been slowly implementing upper-body exoskeleton technology on several of its assembly lines, starting with the Michigan Assembly Plant in Wayne, MI. The recipient of ASSEMBLY’s 2012 Assembly Plant of the Year award builds the Focus compact sedan and the C-Max crossover, but it’s currently being retooled to produce the Ranger midsize pickup truck and the Bronco sport utility vehicle. Ford is also using upper-body exoskeletons at its plant in Flat Rock, MI, which assembles the Mustang.
The passive exoskeletons are used on overhead clamshell assembly lines. Operators on those lines perform a variety of underbody work, such as attaching aero shielding, brake and fuel lines, carbon canisters and exhaust decking, in addition to small parts such as rubber grommets.
“We have identified about 15 to 20 applications for upper-body exoskeletons on our unibody vehicle high lines,” says Smets. “Overhead tasks are ideal for exoskeleton use, because there’s no chance for the device to come in contact with the body of a vehicle, which could scratch or damage it.”
Smets began studying exoskeletons in 2011. At the time, the only devices available were for military and medical applications. When products designed specifically for manufacturing environments became available three years ago, Smets began meeting with vendors. He selected systems that would be appropriate for use on automotive assembly lines and ultimately ended up selecting Ekso Bionics’ EksoVest.
“The United Auto Workers union was involved in the project from day one,” says Smets. “In fact, they funded the acquisition of the first four exoskeletons that we acquired so that they would have ownership of the technology and eliminate any resistance from operators. That helped us evaluate the devices and make the right decisions.”
Initial exoskeleton trials on Ford’s assembly lines began in 2016, followed by a long-term trial in 2017. Smets identified about 25 plant floor applications that would be suitable for exoskeletons. But, it was all strictly voluntary; operators choose whether or not they want to wear one of the devices.
Smets carefully tracked who was using the exoskeleton during the trial period. “One of the things that I looked at was how often they used it,” he explains.
During the initial three-month trial, Smets conducted weekly questionnaires to gauge user feedback on issues such as fit, finish, design, comfort and use. All assemblers reported significant decreases in discomfort in their necks and shoulders after a typical work week. And, they didn’t experience any pain or discomfort in their legs or elsewhere in their body.
“The key is that we weren’t changing the work,” says Smets. “We weren’t trying to make a job that’s unacceptable acceptable.
“At first, it was hard to get people to participate in the exoskeleton study,” notes Smets. “They were very skeptical. But, that eventually changed.”
“My job entails working over my head, so when I get home, my back, neck and shoulders usually hurt,” says Paul ‘Woody’ Collins, a veteran assembler who has worked at Ford’s Michigan Assembly Plant for 23 years. “Since I started using the vest, I’m not as sore, and I have more energy to play with my grandsons when I get home.”
Ford plans to deploy more upper-body exoskeletons at other assembly plants in the near future. However, wearing the devices will not be mandatory; it will be strictly optional.
So far, the initial results have been impressive. Ford has achieved a reduction in employee incident rates and has seen a 90 percent decrease in ergonomic issues such as overextended movements, difficult hand clearance and tasks involving hard-to-install parts.
“Investing in the latest ergonomics research, assembly improvements and lift-assist technologies has helped us design efficient and safe assembly lines, while maintaining high vehicle quality for our customers,” claims Bruce Hettle, group vice president of manufacturing and labor affairs at Ford.
To watch a short video about the pros and cons of upper-body exoskeletons, click here.
To see a video about the future of exoskeletons in the workplace, click here.
Test Driving an Exoskeleton
During a recent visit to Ford Motor Co.’s Michigan Assembly Plant in Wayne, MI, I had an opportunity to “test drive” an upper-body exoskeleton.
The 9-pound device consists of a lightweight tubular frame that slips on like a backpack. My initial reaction was how easy it is to slip in to. I also could move my arms freely.
After pulling my arms through some cuffs and straps, I fastened a few snaps on my arms, chest and waist. I made a few minor adjustments for comfort and snugness, then I was ready to go. The entire process was painless and took less than a minute.
I experimented by holding my arms at different heights and angles. I felt normal when my arms were parallel with the side of my body. But, as I slowly raised my arms up and out, I felt the magic effect of the exoskeleton kick in.
As I raised my arms even further, I encountered weightlessness in my upper body. Once my arms were outstretched above the height of my shoulders, I experienced a weird sensation. Both of my arms quickly shot up with no effort.
I was immediately reminded of a funny scene in the classic movie, “The Christmas Story.” After Randy (the younger brother of the main character, Ralphie) puts on a tight snowsuit, his arms continually spring up like rubber as he desperately tries to lower them.
The Ford engineer and operator who guided me through the unique experience assured me that the exoskeleton was not even on its maximum setting. Otherwise, they said the weightless sensation would be even faster and more intense.
To simulate daily production tasks, I tried using a DC-electric pistol-grip torque tool as cars moved by on the assembly line. After holding the tool over my head with my right hand for a few seconds—both with and without the aid of the exoskeleton—I could feel the difference. While wearing the exoskeleton, my arms were fully supported and I felt like I could work overhead indefinitely. The stress-free support was quite noticeable on my neck, shoulder and wrist.
Overall, I was impressed with the device. During my brief test drive, it exceeded my initial expectations and made me more intrigued by the technology.