# An Approach Based on VR to Design Industrial Human-Robot Collaborative Workstations
## 3 Application to Industrial Case Studies
### Case No.2: Interaction Prototyping for Human-Robot Assembly  
The second case study presents how the proposed VR-based approach can be used to support the human-robot interface design for an industrial context. The case study concerns a collaborative human-robot assembly station. Specifically, an operator and a cobot are in charge of inserting bonding fastener (i.e., bigHead) on a monocoque of a car. The operator has the task of positioning the monocoque near the robot station and starting the automatic phase of the robot, while the robot autonomously applies the glue and places the bigHeads on the monocoque. During the automatic phase, the operator carries out parallel activities and has the task of supervising the robot operations, intervening in case of failure. Although the focus of this scenario is on the design of the HMI to guarantee high-quality human-robot communications, as a first step we considered a possible physical layout of the workstation for this working scenario. To this end, the approach described in Section 2.1 was applied to identify the needed tools and their location in the environment. Specifically, the following elements were identified:  
* Two tables;
* A cobot, with specific end-effector for bigHeads insertion;
* Monocoque;
* A glue dispenser;
* A vision system. Moreover, given that the focus of this virtual environment is to study and design human-robot communication and interaction, relevant items to be included in the scene are the human operator, wearing protective helmet and glasses, and background noise. The resulting 3D scene is represented in Figure 14. It is worthwhile noting that some these elements are very specific for this case study. Nevertheless, they can be easily integrated in the virtual scene, provided that a 3D sketch is available. The same is applied to situational factors, such as noise, personal protective equipment or the presence of a human, whose introduction is relevant in some applications. Given the availability of a virtual rendering of the workstation, it is then possible to focus on the design of human tasks and interaction with the environment. The human-machine interaction mapping phase started from the scenario text description to understand all the necessary interaction aspects. From this, it emerges that the user must interact with both the robot and the system, mostly to receive constant updates on the activities completed by the robot. The communications that the user must send to the robot/system are limited to a few occasions, especially concerning troubleshooting. Initially, the operator must communicate to the system the correct positioning of the monocoque and start the automatic phase through the HMI. From this moment, the interactions are limited to the feedback communication from the robot about its activities and error messages. In case of robot failure during the bigHead application on the monocoque, the operator must intervene by completing the task in hand-guidance (i.e., accompanying the robotic arm towards the direction where to insert the bigHead until it recognizes it) or in hand-over (i.e., removal of the bigHead from the robot gripper and manual positioning). Especially in the hand-guidance phases, it is essential that the user visualizes the robot's response to her/his actions. For this reason, the first identified interaction point to insert the HMI was on the robot station proximity, in order to be clearly visible during a collaborative task execution. Moreover, considering that the operator carries out other parallel activities another interaction point was individuated. This does not correspond to a specific point but it is indicative that the operator could move in the work area, especially near the workbench. The choice of identifying a second interaction point is mainly linked to the case of problem signaling while the operator is carrying out other activities away from the robot's workstation.