Human interaction safety analysis (HISA)
This is a safety analysis method which systematically identifies interaction failures between humans and machines. The focus so far has been on analysis of protocols for transition of control of the dynamic driving task between a human driver and an automated driving system. However, the aim is to extend it to other types of interaction as between humans and cyber-physical systems as well as make use of real-world data to improve the analysis results [HIS1, HIS2].
The process consists of the following steps: (1) propose a communication protocol; (2) create the interaction sequence between a HU (Human User) and a machine as two communicating entities through the HMI, considering the possible combinations of time intervals (Figure 3.8, top left where the machine is an ADS – automated driving system); (3) perform cause-consequence analysis (CCA) by constructing cause-consequence diagrams (CCD) based on the interaction sequences (Figure 3.8, top right), and for each failed event on the CCD perform a fault tree analysis (FTA) considering a model of human behaviour (Figure 3.8, bottom); and lastly (4) perform a risk assessment for identified potential faults and improve the HMI design if the residual risk is considered unacceptable. The results of the analysis should be useful as a part of the argument for safety of the ADS, and thus used in the ADS safety case.
