In order to implement a new generation of urban mobility safely and practically, Hitachi Ltd. and Fraunhofer IESE have combined their expertise in a long-term partnership. The focus is on the development of innovative safety engineering methods for autonomous shuttles – tested using an example scenario based on the Bus Rapid Transit (BRT) system in Japan. BRT roads cross regular lanes and crosswalks, creating complex interaction scenarios that place high demands on vehicle safety.
Dynamic risk management instead of worst-case thinking
Traditional safety models are often based on very conservative worst-case assumptions, i.e. on considering the most unfavorable conceivable situations. Although this leads to a high level of safety, it also results in inefficient behavior, such as unnecessary stops.
Together with Hitachi, the experts at Fraunhofer IESE have therefore developed a more dynamic approach. The “SINADRA” method enables situation-aware risk assessment at runtime, i.e., risks are continuously assessed during operation based on the current situation. “ConSerts” make it possible to react to SOTIF (Safety of the Intended Functionality) faults during runtime and to adapt the system behavior in a targeted manner in order to continue to guarantee safety. This refers to safety-critical malfunctions of automated driving functions that are not caused by technical defects but by limitations of the function itself, environmental influences, or incorrect operation.
This approach is supplemented by Hitachi’s Symbiotic Safety concept, in which the system and the environment are considered more closely together in order to ensure safety. The developed models were transferred into executable software and successfully tested both in simulations and in a real-world test environment on the Hitachi campus in Japan. The results show fewer unnecessary stops while maintaining the same level of safety.
From passive documentation to active safety assurance
As part of the ongoing collaboration, a model-based approach was developed that transforms safety cases – structured evidence and arguments for system safety – from passive documents into active mechanisms for assurance.
“Through our long-term collaboration with Fraunhofer IESE, we have demonstrated that dynamic, situation-aware safety assurance can significantly improve the practicality of autonomous shuttles without compromising safety.”
Satoshi Otsuka, Ph.D., Chief Researcher,
Mobility Automation Innovation Center, Hitachi, Ltd.
Through the systematic traceability of safety case elements with development artifacts and safety artifacts, i.e., with concrete results from system development and the safety process such as requirements, models, or tests, complex validation processes can be partially automated. This link is formally described in the Open Dependability Exchange (ODE) metamodel, a standardized model for structuring safety-relevant information.
A central aspect of this is the so-called ODD coverage (Operational Design Domain). This describes the operating conditions under which an automated driving system can be operated safely, for example, certain weather conditions, road types, or traffic situations. A separate algorithmic solution was developed to check this coverage systematically within a safety case. Overall, the approach enables consistent and effective assurance of automated driving systems throughout their entire life cycle.
Long-standing partnership with future prospects
The multi-year collaboration between Fraunhofer IESE and Hitachi shows how a trust-based, international partnership can sustainably drive technological innovation. The methods developed are transferable to other fields of application and strengthen Hitachi’s position in the area of safe autonomous systems.
