RQ4: Overhead

The results of the overhead analysis are shown in Table 7. According to the results, it can be concluded that the overhead of the safety query for the online safety monitoring is almost negligible since the time spent on PMC is much less than in simulation. In particular, for AFC-DNN1 the differences between the average safety query time and the average simulation time are four orders of magnitude, and it is three orders of magnitude for AFC-DNN2, ACC-SAC, and ACC-TD3. The average simulation time over all benchmark systems is 35.7501 seconds, while the average query time is 0.1032 seconds, which is of two orders of magnitude difference.