Evaluating Ergonomic Design: A User Command Interface for Industrial Exoskeletons
Authors: Alonso Moreno Franco Olmo , Lambranzi Chiara , Pitzalis Roberto , Sposito Matteo , Asgharpour Mahnaz , Park Daegeun , Di Natali Christian , Monica Luigi , Caldwell Darwin , Ortiz Jesus 
Published: August 2024

Industrial workers perform daily activities with a high risk of musculoskeletal disorders. Diverse studies have reported high rates of musculoskeletal disorders among distinct industry professionals, with values exceeding 75% for most occupations considered. Commonly affected body areas include the neck, back (particularly the lower back), shoulders, and lower limbs. A potential solution to reduce the risk of injury among industrial workers is the use of exoskeletons in the workplace. This wearable suit improves ergonomics depending on the body part it supports. From the actuation point of view, exoskeletons can be categorised in three branches: passive, active, and quasi-passive or active. Active exoskeletons contain sensors, actuators, and electric controller boards; these characteristics make them more versatile for adapting the control strategy to the required task. The wearer of an active exoskeleton, needs of a human-machine interface to modify parameters that impact the exoskeleton control strategy. The user command interface is a wearable device that allows easy adjustments when an interaction occurs.Purpose: In this paper, we present an ergonomic assessment of the User Command Interface. The interface plays a crucial role in addressing the challenges faced by developers in optimising industrial exoskeleton capabilities by offering adaptability, control, usability and performance enhancement features. This electromechanical device attached to the exoskeleton provides a solution for achieving user interaction and is open to the user exoskeleton´s assets. However, human factors regarding physical ergonomics have not been addressed with exoskeleton´ users when the interface is in use.Methods: It is important to highlight the difficulties faced when analysing design requirements in wearable devices, particularly in terms of measuring attributes such as comfort. For instance, this term may be defined differently in various studies, sometimes as a standalone design requirement and in other cases as part of a group of requirements. However, comfort was found to encompass aspects such as freedom from discomfort and pain, acceptable temperature, texture, shape, weight, and tightness, all of which contribute to the overall comfort and usability of a device. To assess the interface, we performed a comparison test of three physical ergonomic attributes: comfort, durability, and safety. Using the mapping wearable design requirements method, five shape-like interfaces were evaluated. Four out of five interfaces are previous versions according to the evolution of our interface, and the last one is a mobile phone. This approach of quantifying and analysing design requirements helps in understanding the complex relationships between different terms and ensures a more systematic and thorough evaluation of design aspects in wearable devices.Results: Twenty subjects participated in the study. The results show the statistical differences of the five shape-like interfaces between the attributes of physical ergonomics, including shape, breathability, hygiene, temperature, size, weight, movement, harm, anxiety, and resistance.Conclusions: Aspects of comfort, such as interface size and weight, represent a challenge when users present diverse ergonomics. Although the interface does not represent a hazard to the user when it is being handling, some versions present a more fragile pattern.