2.5.2. AR-Based Instruction Method
CAD
CAD
The first step in building the AR instructions was to create 1:1 CAD models for the piston pump using the SolidWorks software. After that, PTC Creo illustrate was used to build and edit the sequence animation for the AR experience. The 3D instructions for assembly, repair, and disassembly of the two tasks were created based on visual cues and animations. Step-by-step instructions were created using several motion effects (as applicable) for individual steps, such as fly-in/fly-out, fade-in/fade-out, shake, pulse, unscrew, etc. These effects were added to each step individually, and then all steps of one intended instruction were combined into one fluid motion. Also, other resources, such as animated hand tools like a screwdriver, wrench, arrow, and puller, were added. Then, the 3D instructions were published as a PLZ file to be imported by Vuforia Studio software to create the AR experience. Vuforia Studio is a web-based tool used to create and publish AR experiences and enables users to provide step-by-step work instructions and overlay 3D digital content on real-world equipment to provide contextual knowledge. In addition, the programming language JavaScript was used to develop the key features of the applications.Then, the created experiences for the maintenance tasks were published to the cloud-based “Vuforia Experience Service” with quick response (QR) codes and Things. Vuforia Experience Service represents a server used to store and deliver published AR experiences, which allow users to access them on Microsoft HoloLens 1 devices through the Vuforia View application. For displaying the AR instruction, the Vuforia View app stored on Microsoft HoloLens was used for scanning a specific Thing marker placed on the maintenance workplace 130 cm away from the participant. After the Thing Mark was identified, Microsoft HoloLens overlaid a 3D CAD model of the selected task on the user’s surroundings. In this method, the maintenance steps were presented as 3D animated models in the AR environment. The participants can interact with the 3D contents and control the playback of the animation by directing their gaze to the virtual buttons (e.g., play, next step, previous step, reset, name of tasks) placed above the 3D model and making a pinching gesture with their fingers. If the participant clicks the play button, a step-by-step animated sequence for the selected task is displayed. 