This Small Business Innovation Research (SBIR) Phase I project proposes a trunk-supporting exoskeleton that minimizes the forces on the wearer?s back at L5/S1 location during bending and reaching. These systems would decrease the severity and number of work-related back injuries while enhancing workers? safety. By using these devices, automobile assembly and distribution center workers can preserve their natural body postures when maneuvering parts and boxes, and thus substantially reduce the strain associated with such work. Consequently, the risk of back injuries will be greatly reduced in workers when using these devices. In turn, the national cost of treating back injuries will be greatly reduced. This project is in its infancy, but it has the potential to change the way workers maneuver boxes and parts in distribution centers and assembly plants. To accomplish this goal several technical challenges must be overcome. The objective is to conduct a set of orthopedics, ergonomics, and metabolic experiments not only to systematically characterize the system, but also use the experiments for redesign and fine tuning.

The broader impact/commercial potential of this proposed research is to dramatically improve the quality of life for workers. The technologies proposed here will manifest in development of broad classes of exoskeleton devices for workers who repeatedly move light objects in factories, warehouses and distribution centers. This project will decrease the risk of back injuries due to repetitive maneuvers in warehouses, distribution centers, and auto assembly plants. This project will decrease compensation indemnity claims involving back injuries and increase availability of affordable assist systems for workers. The technological impact of this proposed research stems from the system integration approach to developing a class of assist devices customizable for a range of working environments. This effort involves the deep integration and convergence of mechanism design, ergonomics, orthopedics, and models for human spine.

Project Report

We proposed a novel approach to decrease the risk of back injuries among workers who repeatedly go through stooping, squatting, and bending postures while performing various tasks, such as lifting objects in warehouses, distribution centers, and auto assembly plants. US Bionics has developed a novel trunk-supporting exoskeleton (TSE) that effectively decreases the forces and torques on the wearer’s back at the L5/S1 locations. This will lead to a reduction in the spinal forces, thus decrease the incidence of back injuries among workers. During Phase I, US Bionics engaged in research efforts with the following intellectual merit and broader impact. Intellectual Merits: Through this phase I grant, we have learnt that it is possible to reduce the muscle forces in the spine using an exoskeleton system, which produces a torque between the torso and the thigh. While reducing the muscle forces, this system does not increase the perceived level of effort of the user’s wearing the device. US Bionics evaluated the effectiveness of the TSE in reducing the muscle forces on a user’s spine. Electromyography (EMG) activity in the erector spine muscles among 8 participants around the L5/S1 region of the spine was recorded during static stooping, with and without the TSE. EMG probes are attached on four muscle groups: 1. Left Lumbar Erector Spinae (LTES), 2. Right Lumbar Erector Spinae (RTES), 3. Left Thoracic Erector Spinae (LTTES), 4. Right Thoracic Erector Spinae (RTTES). The experiments showed EMG activity reduction across all four core erector spinae muscle groups. This EMG activity reduction corresponds to reduction in muscle forces at the L5/S1 and the compressive forces acting on the lumbar spine. The evaluation result demonstrates the efficacy of the TSE in reducing muscle forces, compressive force on the L5/S1 vertebra, and risk of injury. In addition, energy consumption of 9 participants was measured with and without the TSE. A quantitative metric (change in heart rate) and a qualitative metric (perceived exhaustion Borg scale) were obtained during repetitive squatting tasks. It was found that the average for all participants depicted a reduction in heart rate (~8%). The device helped some individuals significantly (36%), while provided a slightly detrimental or no effect to other participants. The average heart rate reduction in male participants was observed to be about 8%. All the trial participants expressed a perceived rate of exhaustion (on the Borg Scale) to be the same or 1 level lower with the TSE than without the TSE and the participants felt no pain as per the horizontal analog scale. On average, a level of 12 on the Borg Scale was stated by participants. Based on the results, we concluded that the TSE is not only effective in reducing muscle forces, but it also does not increase the perceived effort to perform our target activities. That is, the TSE provides the benefit of injury reduction without apparent increase in user effort. During the Phase I, the TSE was redesigned based on user feedback. The redesign of TSE has reduced system weight and volume, improved user range of motion, and increased device manufacturability and repeatability. These design improvements were mostly focused on the torque generator of the TSE, which provides supporting forces and determines wearer’s range of motion. Additional degrees of freedom were added to the system to increase usability during deep squatting. Broader Impacts: Back Injuries account for the largest number of workplace injuries in the United States. These injuries have been called the nations #1 workplace safety problem by the Occupational Safety and Health Administration. They cost the United States of America 20 billion dollars annually in direct and indirect costs. With the help of the Phase I funding we are able to pursue development and improvement of exoskeleton system which shall aid in reducing this problem. This not only reduces the burden on companies who provide compensation to workers, but also assist workers by reducing the odds of them developing a disability. This technology can keep workers at their jobs longer without injuries, improving their quality of work and life.

National Science Foundation (NSF)
Division of Industrial Innovation and Partnerships (IIP)
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Muralidharan S. Nair
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U. S. Bionics
United States
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