Design of a fail-operational powertrain for automated electric vehicles

Autoren

M.Sc. Tunan Shen, Dr.-Ing. Ahmet Kilic, Dr.-Ing. Jochen Faßnacht, Dr.-Ing. Christian Thulfaut, Robert Bosch GmbH, Germany;
Prof. Dr. Hans-Christian Reuss, Institut für Verbrennungsmotoren und Kraftfahrwesen Stuttgart (IVK), Universität Stuttgart

Jahr

2019

Zusammenfassung

Automated vehicles will change the role of privately owned cars in the future. New mobility solutions like Urban Automated Shuttles (UAS) and Urban Automated Taxis (UAT) can provide mobility as a service with a lower price. As a result, most urban and suburban residents will be able to be mobile without owning a car.
According to a forecast by Roland Berger the kilometers driven with privately owned passenger cars will decrease by approx. 28% in 2030 compared to 2015, while on the other hand the kilometers driven with automated vehicles will increase to 27% of the kilometers driven worldwide. Figure 1 presents an internal analysis of Robert Bosch GmbH regarding the future mobility scenarios. It can be seen that the market volume of UAS and UAT will increase dramatically in the next 10 to 15 years and automated vehicles will take a key role in the future mobility scenarios.
Nowadays, automated shuttles have been deployed in different restricted areas e.g. campus, parking lots and industrial sites [3]. However, the operation still relies on a safety steward who is responsible for transitioning the vehicle to a safe stop at the ego lane and ensuring the safety of the passengers in case of failure. To enable the shuttle operation without a safety steward, the automated vehicle must be capable of achieving a minimal risk condition by itself in case of a failure. To fulfill this requirement, several relevant systems have been designed with redundancy to enhance the reliability of systems, such as sensors, computing, braking, steering, and power supply systems. However, if the powertrain system of an automated driving vehicle fails during a trip, the vehicle might stop in the middle of a traffic lane without adequate measures to guarantee sufficient safety. The passengers in the vehicle may stay in danger in some situations. Therefore, a higher reliability of the powertrain system is recommended for a safe automated driving vehicle.
This paper presents a fail-operational powertrain solution, which is able to achieve a safe stop transition to the next parking area in case of a failure in the powertrain system.
This paper is organized as follows. In Section 2, related requirements for the design of the powertrain system are discussed. Section 3 presents the development of a failoperational powertrain topology and subsequent redundant components. Section 4
introduces a concept to avoid critical failures in the powertrain by predictive diagnosis.
Section 5 briefly summaries the main results and concludes this paper.