# Human Cognitive and Motor Abilities in the Aging Workforce: An Information-Based Model
## 5 A Case Study from the Automotive Industry  
The model defined in the previous section has been tested on a case study inspired by an assembly line of an automotive factory in which high pressure pumps for diesel injection systems are assembled. The line consists of highly automated workstations, and workstations with a small degree of automation. The line is operated on three eight hours shifts. The line has a cycle time of 45 (s). One component of the pump, the flange, is pre-assembled on a sub-line consisting of three workstations (WSs). The sub-line is operated only in the first eight hours work shift and provide flanges for the subsequent three shifts, thus having a cycle time of 15 (s). A semi-automated punching machine is operated in each WS. Operators are in charge of pre-assembling and verifying the right position of components on the flange and of initiating the process on the machine. At the end of the process, operators of each WS perform a (visual) quality control on the product in order to identify scraps. The case study allowed to test the model and to find the operator-machine allocation minimizing idle time of the line or equalizing workloads of the WSs. Furthermore, the developed model allows to verify whether an operator is eligible to work on a WS or whether his/her operating time (performance time + machine time) is not compliant with the cycle time. In the case study, three WSs and five operators are considered. The operator's characteristics (age and sex) are in Table 6.  
In the first WS a thrust ring is set into the flange; in the second WS the oil seal is assembled onto the flange; in the third WS a bushing is assembled into the triangular ring of the flange. Each WS is composed by multiple sub-tasks that can be classified as having more cognitive or motor information content. For each WS, the information content of the cognitive part of the task (\(\text{I}_{\text{c}}\)) and the information content of the motor part of the task (\(\text{I}_{\text{m}}\)) are calculated by Equations (1) and (8a), respectively. As far as \(\text{I}_{\text{m,MTM}}\) term is concerned (Equation (8b)), the time required for the simple movement of the upper limbs is obtained from MTM standard times. The time measurement unit for each simple movement is expressed in TMU (Time Measurement Unit), being 1 TMU is equal to 0.036 (s). TMU values and the equivalent MTM times used for the simple actions of reaching, grasping, moving and releasing are in Table 7. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Operator** & **Sex (M/F)** & **Age** \\ \hline A & M & 25 \\ B & F & 35 \\ C & M & 50 \\ D & M & 60 \\ E & F & 60 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Operator’s characteristics. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Reach** & **Grasp** & **Move** & **Release** \\ \hline Distance (cm) & 40 & - & 30 & - \\ TMU Value & 11.3 & 2 & 12.9 & 2 \\ MTM (s) & 0.41 & 0.07 & 0.46 & 0.07 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: TMU values for the simple actions: Reach, grasp, move and release. MTM: Method-Time Measurement. For each single sub-task of the WSs, the information content is provided in Table 8.  
For each operator assigned to each WS, the performance times are obtained by Equation (15). In Table 9 are summarized the operating times as the sum of the operator performance times calculated and machine times. Machine time is 7.2 (s), 9.6 (s), and 8.6 (s), for WS one, two and three, respectively.