Simulation Techniques for Determining Motorcycle Controllability Class According to ISO 26262 2018-32-0060
The ISO 26262 standard regulates the safety functions of electrical and electronic systems within road vehicles. We have accumulated case studies based on actual riding tests by subjective judgiment of expert riders to define a method for determining the controllability class (C class). However, the wide variety of practical traffic environments and unpredictable vehicle behaviors in case of malfunction prevent riding tests from being truly comprehensive. Furthermore, under some conditions, actual riding tests may pose unacceptable risks to test riders. In Part 12 Annex C of ISO/DIS 26262, simulation is cited as an example of a technique for comprehensive evaluations using the Controllability Classification Panel.
This study investigates the usefulness of numerical simulations for evaluating the C class of a motorcycle experiencing a malfunction in either the front or rear brakes. To estimate the rate of successful harm avoidance in this scenario, we calculate whether a representative rider can stop while leaving a safe distance to a hazardous object which is considered useful in judging the C class. For the calculations, we use time-series waveforms of the brake actuation force described by parameters such as the brake reaction time and the maximum brake actuation force. These parameters are chosen from the data recorded about riders’ compensatory control actions during the actual riding tests. The rates of successful harm avoidance obtained from the numerical simulation almost agree with the results of the actual riding tests. This agreement indicates the rate of successful harm avoidance can be estimated with simulations that use brake operation waveforms to model the compensatory control action.