## 3 A Knowledge-Based Approach for the Investigation of Collaborative Workplaces
### Knowledge Management  
The _Knowledge Management_ consists of the organization of the acquired knowledge into homogeneous \"containers\", and in the definition of the existing relationships among them. The knowledge associated with the collaborative workplace is divided in five main domains that collect all the homogeneous elements and respond to a specific need of the collaborative workplaces:  
* Logistic domain: refers to all issues related to the division and management of the workspaces, the inclusive and exclusive working areas, the available space, and the management of the material flow strategy within the workplace layout.
* Technological domain: refers to all issues directly correlated with the involved resources, their features, number, and characteristics.
* Safety and ergonomics domain: refers to the human wellness, safety working conditions, and the performance of the control system, including the guards and protective devices.
* Process domain: refers to all issues related to the production, time, task sequencing, interaction, and communication between humans and robots.
* Economic domain: refers to costs and benefits about the collaborative workplace, as well as the performances evaluation.  
Twenty-one elements belonging to these domains are presented below. They are parts or features of the collaborative workplace that face specific aspects of the problem and collect homogeneous information:Physical limits (PL): available space and any obstacles;
* Workspaces (WS): division into the main workspaces that define the whole workplace layout;
* Paths (P): accesses and exits of the workplace and related paths;
* Feeding (F): means and strategies for material supply;
* Workpiece (WP): main piece to be worked and its components;
* Equipment (EQ): furniture and instruments;
* Usable devices (UD): control devices under operator control;
* Operator (O): operator characteristics;
* Robot (R): robot characteristics;
* Autonomous Guided Vehicle (AGV): AGV characteristics;
* Ergonomics (ER): ergonomic constraints and limitations;
* Environment (EN): environmental working conditions;
* Minimum distances (MD): minimum distance set among both fixed and mobile resources;
* Safeguarding perimeter (SP): physical or virtual workplace limit;
* Safeguarding devices (SD): device not under operator control;
* Type of work (TW): operation to be performed on the workpiece;
* Task sequence (TS): elementary operations scheduled to be performed by humans and robots;
* Human-Robot Collaboration (HRC): interaction between humans and robots;
* Human machine interface (HMI): communication between human and robot;
* Costs (C): economic constraints;
* Benefits (B): key performance indicators (KPI).  
Domains and elements represent the framework of the collaborative workplace (Table 1). Once the structured framework is defined, the subsequent need is to identify and represent the network of relationships among the elements. Therefore, the collaborative workplace is modeled as a graph (G = N, E) [51] made of a set of nodes and edges [5] representing, respectively, the elements and their dependencies. The relations among the nodes are highlighted by means of a direct graph (digraph) or an adjacency matrix (Table 2) where the values 1 or 0 indicate whether the elements on the row have a direct connection with the elements on the columns, or not [52; 53].  
Considering Table 2, the first seven columns (i.e., _Workpiece,Type of work, Physical limits, Ergonomics, Environment, Minimum distances_, and Costs) are intended as source nodes or external constraints. They are not influenced by the other nodes of the network. The central nodes are all configurations that depend on the designer's choices. The last nodes are intended as outputs of the design process, such as the workspaces and the paths that are the consequences of previous decisions. Thus, a flow going from the source nodes to the sink nodes is generated. The designer has an overall view of the topic at his disposal and can more consciously deal with the workplace layout planning, etc.