# An Interactive Method for Detection of Process Activity Executions from IoT Data +
## 4 Method to Identify Activity Executions
### Then Details-on-Demand: Determine Start and End Patterns and Activity Signatures  
Each component and time frame determined to be relevant is then investigated in more detail. The plots for each component are analyzed with the goal of finding and annotating specific patterns related to one or more sensors and actuators that might indicate either the _start_ time of an activity or the _end_ time of an activity. Once the start and end events for an activity are identified, the process analyst provides a suitable label for the activity. **Example 5**. : _Figure 10 shows the details for the relevant time frames of the WT_1 (workstation transport) component including annotations for the start and end of activities. Given all sensors and actuators have been inactive, a change in the speed value of one of its motors from 0 to \(-512\) (for moving backward) or to 512 (for moving forwards), depending on the initial position of the transport gripper, signifies the start of an activity. In our context, this refers to the activity Transport from Oven to Milling, which needs to be provided as a label by the process analyst. Similarly, the end of an activity is indicated by a change in the last active motor's speed value to 0 followed by a longer period of inactivity._  
**Example 6**. : _Figure 11 shows the details for one relevant time frame of the HBW_1 (high-bay warehouse) component including annotations for the start and end of activities. Again, the change in the speed value of one of the motors from 0 to \(-512\) indicates the start of an activity, namely the Store Workpiece activity as labeled by the process analyst. The end of the activity is indicated by a  
Figure 10: Details of the IoT data filtered by the WT_1 component with manual annotations. \begin{table}
\begin{tabular}{c c c} \hline \hline
**CPS Component** & **Relevance Part 1 (18:40–18:53)** & **Relevance Part 2 (18:53–19:07)** \\ \hline VGR\_1 & X & X \\ \hline HBW\_1 & X & X \\ \hline OV\_1 & – & X \\ \hline MM\_1 & – & X \\ \hline WT\_1 & – & X \\ \hline SM\_1 & – & X \\ \hline EC\_1 & – & – \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Relevance of CPS components for the different (time-related) parts of the data set. position switch being pressed (i.e., its value changes from 0 to 1) as an effect of moving the loading robot. The remaining active sensor values refer to the target positions of the warehouse robot, which will only change with the start of a new activity in the HBW_1 component. The irrelevance of these sensors at this point is part of the analyst's domain knowledge._  
**Example 7**. : _Figure 12 shows the details for one relevant time frame of the VGR_1 (vacuum gripper robot) component including annotations for the start and end of activities based on sensors and actuators changes as well as more specific attributes. This central transportation component is relevant in many parts of the process execution. Here we see that refinements of detected activities might be necessary as a seemingly coherent activity that is preceded and succeeded by periods of inactivity can actually represent a sequence of several shorter activities. As the vacuum gripper robot is constantly moving and with this, its motors and compressors as well as switches are constantly active or triggered, and different types of sensors/actuators need to be taken into consideration to identify activity borders. In the case of this robot being responsible for the execution of transportation activities from one station to another, the change of the target position values provides good hints for the start and end of this type of activity in general. The change of one or more of the target coordinates usually indicates that one target was reached, and with that, the associated activity ended (e.g., in combination with the status of motor movements), and the movement to a new target is started as part of a new activity. However, we may also see movements to more than one target as part of one activity.