## 2 Materials and Methods
### RTMN 2.0--Extension of RTMN
#### 2.2.5 Other Extensions and Modifications  
RTMN 2.0 not only extends the HRC area but also covers other additional functionalities. Requirements and KPIs have been added to the modeling language. The aim is to achieve traceability from requirements through tasks, skills, and primitives to reach the defined KPIs. The process notation is added to represent the different processes. We also made some modifications to the skill and primitive notations in the first version of RTMN so that the distinction would be more obvious. Requirements and KPI  
Key performance indicators (KPIs) form a specialized set of metrics steering management activities towards improving company performance, representing quantitative measures of critical success factors (CSFs) in enterprises [55]. They serve as variables reflecting progress toward goals while aligning with the company's vision and strategies [55]. Displaying KPIs is essential in order for supervisors and employees to seek improvements and reach for better performance [55]. In an HRC environment, safety and ergonomics are widely acknowledged as crucial pillars, while in a business context, productivity, encompassing both effectiveness and efficiency, and economics must be considered [55]. Therefore, after analyzing numerous research papers, [PERSON] et al. divided the various KPIs related to HRC into the following four areas: \"Productivity\", \"Economics\", \"Safety\", and \"Ergonomics\" [55]. We adopted their systematic approach and categorized the requirements and KPIs into these four categories. The requirement notation (see Figure 16) and KPI notation (see Figure 17) were added to RTMN 2.0 to visualize the business requirements and KPIs at the process level. We could also assign requirements and KPIs at the task level if needed. \begin{table}
\begin{tabular}{l l l l l} \hline \hline
**Sequence** & **Parameter** & **Equation** & **Value** & **Action** \\ \hline \multirow{2}{*}{1} & \multirow{2}{*}{Bin status} & = & Empty & Fill up bin \\  & & \(\
eq\) & Empty & Do nothing \\  & & = & \(\mathrm{V_{R}}\)\({}^{*}\)(\(\mathrm{T_{R}}\)\(+\)\(\mathrm{T_{S}}\)) + \(\mathrm{V_{H}}\)\({}^{*}\)(\(\mathrm{T_{R}}\)\(+\)\(\mathrm{T_{S}}\)) & Stop robot \\ \multirow{2}{*}{2} & \multirow{2}{*}{Distance, robot and human} & \multirow{2}{*}{\(>\)} & \(\mathrm{V_{R}}\)\({}^{*}\)(\(\mathrm{T_{R}}\)\(+\)\(\mathrm{T_{S}}\)) + \(\mathrm{V_{H}}\)\({}^{*}\)(\(\mathrm{T_{R}}\)\(+\)\(\mathrm{T_{S}}\)) & Robot run at collaborative speed \\ \multirow{2}{*}{3} & \multirow{2}{*}{Quality check} & = & Accepted & Move product to next station \\  & & = & Rejected & Move to rejected bin \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Rule table. Figure 16: Example of using decision notation. The requirement notation (see Figure 17) represents the business requirements of a robotic process/task. It has the following properties: name, formula, KPI, input, output, precondition, and postcondition. One can set constraints using preconditions and postconditions. For example, one can add a postcondition--the sum of net machine utilization and net operator actuation is 100%. The KPI notation defines the key performance indicators linked to the requirements (see Figure 18). Table 3 illustrates the general KPIs for the HRC robotic processes, among which a few are related to humans: accident rate, net operator actuation, and human exposure to chemicals. The inputs for calculating the KPIs come from ROS, the robot control level. From primitives and skills, we can obtain the input values, use them for calculating the KPIs, and validate the requirements. Through this, traceability of the requirements and KPIs is achieved. To be more specific, KPIs are calculated automatically based on the values created in different layers of the robot system. For example, for a pick skill, it is tracked whether the pick is successful or not. The success rate of picking is calculated by the number of success picks/total pick attempts.