From the development of the earliest tools, mankind has been on a continuous quest to invent machines and equipment to help us to undertake more tasks, do more in less time, and do more with less effort. A development in the last category is the external skeleton, or exoskeleton, a machine worn by the user to assist in all sorts of tasks, providing strength, endurance, and in some cases, additional capabilities. The first modern concept of an exoskeleton was patented in 1890 by engineer Nicholas Yagin, and in recent decades the concept has been modernized and a few prototypes built. Among the most ambitious have been exoskeletons developed for military use, incorporating armor, power, and communications. One of the early military units, General Electric’s Hardiman, provided quite a bit of strength, multiplying the user’s effort by a factor of 25, and could lift a maximum of 750 lbs. Like other early units, the controls weren’t sophisticated enough for it to be useful, and it was just too heavy at 1,500 lbs.
In the last few years, exoskeletons and other assist devices have gained traction. Lightweight materials, improved power technologies, and modern control systems have done a lot to improve the initial concepts. One of the participants in this field, Levitate Technologies Inc., San Diego, took a different approach, making a simple, self-contained, lightweight unit. Its name, Airframe, hints at its weight, which is just 5 lbs. An assisting unit, it supports the arms for workers who do extensive amounts of work at the shoulder level or overhead.
Providing a Boost for Lifting
Imagine installing a sprinkler system, hanging drywall, or running conduit in a residential building for hundreds or perhaps thousands of tenants; working on an automobile assembly line, overhead, installing exhaust system components or brake lines; or welding overhead off and on throughout the day. These tasks require a lot of lifting materials and tools all day long.
Sure, some employers rotate tasks, and workers tend to be really good at improvising labor-saving devices, but improvised methods have limitations, safety is always a concern, and in a strictly controlled work environment, they’re not allowed. These are cases in which a system that provides some support for a worker’s arms would be ideal. The Airframe is one such system.
“The system has three main components,” said Joseph Zawaideh, Levitate’s vice president of marketing and business development. “It has a frame, which the user wears like a backpack. It has cassettes that have pulleys, cables, and springs to provide lifting power. Finally, it has arm rests that capture and support the user’s arms.”
The frame comes in four sizes, and the arm rests are available in three sizes. Cassettes are available in six force levels that correspond to the task at hand. Its modular design means that the system can be tailored to the user.
Because it relies on a system of pulleys, cables, and springs, it’s self-contained. It doesn’t run on batteries or any other power source, internal or external. When the wearer’s arms are at his sides, the system is neutral, allowing him to use his arms as he normally would. When he lifts his arms, the mechanism inside the cassette creates a progressive mechanical force that compensates for the weight of the wearer’s arms and tools. When he lowers his arms, the system disengages progressively and returns to neutral.
The exoskeleton is Levitate founder Mark Doyle’s sixth invention. A previous development assisted surgeons. Extended medical procedures are fatiguing, and it’s common practice to use an arm rest, but the arm rest is bolted to the surgery table and therefore isn’t mobile. Doyle came up with a unit that, like the Airframe, is mobile. Zawaideh cited Doyle’s background in the medical field as an excellent foundation for developing and testing the new version, facilitating a clinical approach. While the system for relieving fatigue for doctors was a success, Zawaideh thinks that the Airframe has been accepted more readily by manufacturers.
“Toyota commissioned a study con-ducted by Iowa State University,” he said. “They used a system of muscle sensors to gather 10,000 points of data per second and determined that the unit does what it was designed to do, relieving stress on the arms and spine and transferring it to the hips,” he said. In this case, spine refers to the entire spine. While lumbar vertebrae tend to be the most susceptible to strains and other injuries, the Levitate unit has been shown to relieve stresses on the entire back and neck. Toyota saw so much value in the unit that the automaker made it standard-issue personal protective equipment (PPE) for workers who work at shoulder level and higher. “It’s PPE, just like safety shoes,” Zawaideh said.
Zawaideh pointed out that the exoskeleton isn’t a single product, but a family of products. The company makes several versions of the exoskeleton for specific working environments and applications. Specialty units include exoskeletons that are fire-retardant, well-suited to manufacturing work such as grinding and welding; units that are electrostatically neutral for painting applications; frames that are compatible with fall-protection harnesses for working at heights; and units that are compatible with explosive environments.
Regardless of the specific model, getting the fit just right is critical. The fit isn’t based on overall height but two critical dimensions: spine length and forearm length. Beyond this, the frame has several adjustments so each wearer can fine-tune the fit, Zawaideh said.
Still, sizing a unit is a matter of precision, a task for which the company provides training. Optimal fit is needed for optimal comfort, and optimal comfort is needed for optimal buy-in. Zawaideh is well aware that workers can be at odds with management and that participation in any new trend, acceptance of any new device, and compliance with any new directive isn’t guaranteed.
“All of the components have been designed with attention to detail so the users will wear the unit,” he said.
Stronger or Longer?
Although a common goal among exoskeleton manufacturers is to make a person stronger, Zawaideh pointed out that the Airframe isn’t like the aforementioned Hardiman unit, intended to provide 750 lbs. of lifting force. Because the Levitate unit transfers the burden to the user’s hips, he still bears the entire weight.
“It doesn’t make a person stronger,” Zawaideh said. “It allows a person to be less fatigued at the end of the day.”
Levitate Technologies Inc., www.levitatetech.com