# Designing a User-Centered Inspection Device's Handle for the Aircraft Manufacturing Industry
## 1 Introduction
It should be highlighted that the aircraft manufacturing workforce presents high WMSD rates; however, the exposure to risk factors is difficult to assess due to the wide variety of parts and irregularity of tasks performed in this industry [18]. In this domain, a research gap has been highlighted, highlighting the need for ergonomic studies about biomechanical risk factors in aircraft production lines [19]. Alongside this need, the current study is focused on the aircraft manufacturing industry, specifically aiming toward the inspection tasks performed by workers on the surface of metallic airplanes' structural parts. In the traditional workflow, the workers visually inspect these surfaces, take photos of the defects found, and create a report about the inspected parts. These inspection tasks involve the use of various hand tools (e.g., ruler, magnifying glass). Along with biomechanical risk factors (such as handling different tools and the adoption of awkward postures [20]), inspection workers also undergo cognitive overload since the task involves information-intensive processes [21]. In this domain, the reduction of the number of manipulated accessories and the digitalization of the process are essential requirements to optimize the production flow and the inspection precision, as well as to reduce the cognitive workload and task completion time [22]. This consists of a relevant research gap, and the current study corresponds to a first of its type, as there is no complete portable device like the one developed by our team. Consequently, there is no literature studying the most appropriate handle for a similar device in the context of aircraft inspection tasks. In addition, our study is developed in the sense of respecting a user-centered design, as proposed by the emergent paradigm of Industry 5.0, being the human factors the center of the industrial processes [23; 24]. Based on these assumptions, a novel device was designed to maximize the efficiency and the biomechanical conditions of these inspection tasks. The device consists of a portable artificial vision system intended to (1) capture and process images of the defects (classify and measure defects' dimensions) and (2) automatically generate digital reports with the inspection results. As this device will be handled by the workers, an appropriate design of its handle is needed to guarantee its suitability for its end-users and inspection tasks. Three different handles were proposed beforehand, and the current study aims to find out which handle allows for  
1. The best ergonomic conditions;
2. The best stability while holding the device during inspection tasks. To support these objectives, this study employs an innovative and comprehensive ergonomic assessment, including qualitative aspects concerning the comfort perceived and quantitative data related to performance indicators and ergonomic conditions. Relative to the quantitative data collected, it should be noticed that this involves measuring the times required for image capture, stability metrics, electromyographic (EMG) data, and kinematic analysis (using inertial measurement units (IMU)).