Design and Evaluation of A Wearable Adaptable Setup System for Occupational Exoskeletons

Background: Industrial activities depend upon tasks involving manual material handling; these expose workers to considerable risk of injuries causing low back pain and musculoskeletal disorders. A potential solution for this problem presents the use of wearable robots known as exoskeletons. Their purpose is to improve ergonomics and reduce the load on the lumbar spine. Exoskeletons can be classified in two categories according to the actuation type: (i) passive, and (ii) active. Active exoskeletons are based on the principles of man-machine interaction and equipped with drive, sensor and control systems. Such devices require system adaptation in diverse scenarios to produce the proper assistive modulation forces for the user. A novel solution is allowing the user access capabilities to certain areas of the exoskeleton controller. The user command interface is a wearable adaptable setup system device for occupational exoskeletons. This device commands the interactions between the user and the exoskeleton to achieve easy adjustments in the system.Purpose: In this paper we present the design and evaluation of a human-machine interface called the User Command Interface, a wearable device to access the different domains of the exoskeleton control system. The interface is an electro-mechanical device attached to the exoskeleton. Its design is divided into two software layers, a hardware architecture and the mechanical interface. The main objective is to control who has access to the exoskeleton and how some domains could be modified without affecting the safety of the user and performance of the exoskeleton. There are twenty actions you can perform using the device, seven of them directly affect the exoskeleton's operation. Some examples of the actions you can do are: (i) accessing the exoskeleton system using fingerprint recognition, (ii) calibration (iii) parameters modification, (iv) monitoring the exoskeleton's signals, and (v) displaying instructions as safety rules or tutorials. Our group is focused in the design and development of upper/lower-limbs active occupational exoskeletons such as XoTrunk and Shoulder-sideWINDER.Methods: To assess the interface we performed functionality, experience, and usability tests. We divided the experiment according to the type of interactions (interface-only and interface-exoskeleton interaction) between the user, the interface, and the exoskeletons. The interface-only interaction evaluates the navigation intuitiveness of the graphical layer and the functionality of user data-base management. On the other hand, the interface-exoskeleton interaction assesses the rapid parameter configuration during lifting tasks related to real scenarios.Results: In total 52 test subjects participated in the study. The evaluation was most frequently conducted using controlled tasks. The study results are divided in: (I) subjective results (user pain points and system usability scale), and (ii) completion time for activities. The evidence shows that the assessment of the interface is a dynamic process. There are statistically significant effects in terms of usability and the completion time of the tasks.Conclusions: The interface allows simple access to the exoskeleton's adjustments and user database management. After evaluation, the device presents a solution for occupational exoskeleton design matters when the user requires parameter modifications during task performance.