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Towards Reducing Risk of Injury in Nursing: Design and Analysis of a New Passive Exoskeleton for Torso Twist Assist
Event Type
Poster Presentation
TimeThursday, April 152:00pm - 3:00pm EDT
LocationHospital Environments
DescriptionThroughout the last decade as one of the emerging wearable technologies, Exoskeletons have demonstrated a potential in improving the body capacity to complete physical tasks [1], [2]. For example, exoskeletons are implemented for rehabilitation, wherein the device helps in controlled recovery of patients; and mobility, enabling a patient to walk [3]. However, considering the increasing physical demand on healthcare workers, especially with the recent pandemic, personnel responsible for providing care and safety are further exposed to the risk of Musculoskeletal Disorders (MSDs). In 2019, nursing aides displayed the second largest number of cases of work-related injuries (~15 thousand) with the highest percentage (52%) involving MSDs [4]. Furthermore, most nursing personnel (~85%) are females and their relative less physical strength implies a higher risk of injury. The costs to the healthcare industry due to such injuries (~1.7 billion USD) are expected to increase more due to the nursing shortage (retirement) and increase in demand (aging and obesity) [5]. The benefits of providing an exoskeleton in nursing could not only reduce such costs and reduce the risk of injuries but could also help nurses in delivering faster and more efficient care.
Implementing exoskeletons within healthcare is yet challenging due to the highly volatile hospital environment and the wide variation in exoskeleton types. Recent studies display difficulties in developing a technology acceptance model of exoskeletons for healthcare workers stating cognitive demands and ethical concerns as key factors while working around the patients [6]. However, many physically challenging tasks exist wherein physical interaction with the patient is not necessary and implementing an exoskeleton could greatly benefit the performance of operations. One example of such tasks is setting an operating room both, pre- and post-surgery which involves repetitive lifting of equipment. Among the needed lifting/lowering events, twisting is very common; in contrast to the recommended approach of pivoting legs and facing the load. This could lead to an awkward posture during the task execution, increasing the potential risk of musculoskeletal disorders. Therefore, we are working towards developing an exoskeleton for relieving the load on the musculature while still ensuring optimum performance in the dynamic hospital environments.
Considering the complexity of adopting an exoskeleton in hospital environments, the requirements by nurses dictate need for a compact, flexible and comfortable assistive device [6]. Addressing these needs, we have designed the exoskeleton to be attached to the torso of a person and will include a mechanism consisting of two actuators. Our bio-inspired assistive device represents artificial muscles in the form of a linear actuator attached to the hip in a similar manner as an oblique muscle of the human body. Further, we have designed the device in the form of a module, which can thus be worn alongside a full-body exoskeleton, if required for heavy lifting. Moreover, with electromagnetic interference concerns of an operating environment, our design is built to be fully-passive and the use of purely mechanical elements would ensure safe operations. Further, our novel design features a cable mechanism to actuate the spring-based actuators. Our study demonstrates such a design, which was developed using a manikin representing the 50th percentile male stature. Moreover, the method of inverse kinematics was implemented simultaneously to determine the dimensions of the actuator. The device offers flexibility of torso and provides with maximum rotation of 52, 25 and 22 degrees (with stationary hip joint) along the transverse, sagittal and coronal planes. The same was verified by developing a 3D Computer Aided Design (CAD) model, which was then imported into a Multibody Dynamics Solver (ADAMS), wherein a simulation of torso rotation was performed for a duration of 1 second. Using spring stiffness and damping coefficients of 0.5 N/mm and 0.1 N-sec/mm respectively for each of the two springs, we obtained a maximum spring force ~25N in each of the springs for a rotation angle of ~30 degrees of upper frame at the end of 1 second.
Our work shows the methods used to design a wearable assistive device, which may reduce the physical demands and possibly the risk of injury in nursing, particularly for movements involving the twisting of torso. The next steps would include an in-depth focus on the mechanical aspects (kinematics and dynamics) of the actuator (e.g. spring stiffness, length, locking mechanisms, etc.). A participatory design approach will be implemented by modifying the design by collecting end-user feedback and concurrently performing laboratory assessments using human subjects. The future work will also include consideration of factors like adjustability and usability along with design of wearability features for mounting the device. Implementation of such a wearable exoskeleton for the twisting task in manual lifting could potentially improve the safety and performance of the wearer. This will also propel the research and development of assistive devices forward, making them more applicable to the real-world scenarios involving complex tasks in the healthcare sector.

References:
[1] E. Rashedi, S. Kim, M. A. Nussbaum, and M. J. Agnew, “Ergonomic evaluation of a wearable assistive device for overhead work,” Ergonomics, vol. 57, no. 12, pp. 1864–1874, 2014.
[2] P. M. Kuber and E. Rashedi, “Product Ergonomics in Industrial Exoskeletons: Potential Enhancements for Workforce Safety and Efficiency,” Theor. Issues Ergon. Sci., 2020.
[3] A. P. Johnson, M. Gorsic, Y. Regmi, B. S. Davidson, B. Dai, and D. Novak, “Design and Pilot Evaluation of a Reconfigurable Spinal Exoskeleton,” Proc. Annu. Int. Conf. IEEE Eng. Med. Biol. Soc. EMBS, vol. 2018-July, pp. 1731–1734, 2018.
[4] U.S Bureau of Labor Statistics, “Injuries, Illnesses, and Fatalities,” 2020. .
[5] J. X. Liu, Y. Goryakin, A. Maeda, T. Bruckner, and R. Scheffler, “Global Health Workforce Labor Market Projections for 2030,” Hum. Resour. Health, pp. 1–13, 2017.
[6] E. Read, C. Woolsey, C. A. Mcgibbon, and C. O. Connell, “Physiotherapists ’ Experiences Using the Ekso Bionic Exoskeleton with Patients in a Neurological Rehabilitation Hospital : A Qualitative Study,” vol. 2020, 2020.