## 5 Case Study
### Collaborative Workplace for Inspection of Welded Parts  
The proposed case study is a collaborative workplace that concerns the welding points quality check carried out by means of ultrasonic technology. It involves the adoption of a human operator and a cobot. The operator is concerned with taking and carrying the component whereas the cobot executes the inspection. The cobot is equipped with a specially designed ultrasonic end-effector. The workpiece to be inspected requires a precise adjustment on the dedicated stand. After the inspection, the operator picks up the component from the dedicated stand and deposits it on the outfeed stand. The main activities of the operator are: carrying the component, precise positioning it and monitoring as long as the cobot execute the inspection. The aim of this section is to generate an optimized layout by means of the proposed Knowledge-Based Approach. For this reason, the parameters of the quality inspection as well as the part to inspect, are not considered during the designing of the layout. The authors focus the attention on the category of application, i.e., _Inspection_, rather than the specificity of the case study. The four steps of the proposed approach, i.e., (i) task analysis, (ii) task centers allocation, (iii) constrained optimization problem solving, and (iv) rough layout definition, are applied aiming at designing a standard compliant and optimized layout for this case study. _Task analysis_. The task assignment (Figure 8) is analyzed as the main input of the entire process. The task analysis allows defining the elements formalized in Section 4.2:  
1. The set of involved passive resources \(P\);
2. The set of involved active resources \(A\);
3. The set of elementary tasks composing the entire operation and their attributes (i.e., type and level of interaction);
4. The set of the task centers distinguished by type (i.e., HTC, RTC, and CTC) according to the procedures described in the previous chapter. Table 4 indicates the details of the information obtained from the task analysis including the task centers list related to all tasks. Thus, the matrix \(T_{tc}\) of task-task center assignments introduced in Section 4.2 can be deduced from Table 4.  
Figure 7: Conceptual layout of the HRC workplace optimized by computing the placement of Human Task Centers (i.e., HTC1, HTC2, HTC3, and HTC C) and Robot Task Center (i.e., RTC1). The coincidence between HTC2 and RTC1 identifies the Collaborative Task Center (CTC) within the Collaborative Space. The chosen collaborative robot is a UR10 cobot produced by Universal Robot, with performance level \"d\", category 3 according to ISO 13849 [61]. It has six rotational joints, a payload of 10 kg and 1.3 meters of maximum reach. The cobot is equipped with an end-effector tool that enables the robot to accomplish the inspection activity. A dedicated Human Machine Interface (HMI) simplifies the cobot control and improves the Human-Robot Collaboration. The set of required passive resources is the following:  
1. Infeed stand;
2. Outfeed stand;
3. Inspection stand;
4. Robot pedestal;
5. Human Machine Interface. According to the proposed approach, \"transport\" task needs two task centers: the first task, i.e., \"loading workpiece in the control station\", needs the _Human Task Center 1_ where the operator takes the workpiece, and the _Human Task Center 2_ where the operator places it. The following tasks are \"process\" or \"control\" tasks, performed sequentially on the same workpiece. Therefore, they are all executed at _Human Task Center 2_ and _Human Task Center C_. Task 6 is assigned to the cobot that has to achieve all the inspection positions. The cobot carries out the task under the human supervision, in a collaborative manner. This means that the _Robot Task Center 1_ coincides with the _Human Task Center 2_, identifying a _Collaborative Task Center_. Moreover, task 7, linked to _Human Task Center 2_, is the collaborative task performed by the human being.