# Safety-Oriented System Hardware Architecture Exploration in Compliance with ISO 26262
## 4 Safety-Oriented System Hardware Architecture Exploration Framework
### System Hardware Architecture Exploration with Safety and Hardware Overhead Consideration
#### 4.3.2. ASIL-Oriented Hardware Architecture Exploration Algorithm
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**Hardware** & **Failure** & **SR** & **Failure** & **FD** & **V** & **SM** & **FMC** & **RF/SPF** & **VI** & **L** & **FMCL** & **LMPF** \\ \hline CAN Bus & \(2.4\times 10^{-7}\) & x & Module failure & 100\% & Duplication & 100\% & 0 & x & Duplication & 100\% & 0 \\ Brake ECU-14 & \(3.3\times 10^{-7}\) & x & Module failure & 100\% & K/N & 100\% & 0 & x & K/N & 100\% & 0 \\ EBM-14 & \(4.2\times 10^{-7}\) & x & Module failure & 100\% & K/N & 100\% & 0 & x & K/N & 100\% & 0 \\ AEB MCU & \(3.8\times 10^{-7}\) & x & Module failure & 100\% & Duplication & 100\% & 0 & x & Duplication & 100\% & 0 \\ Brake pedal & \(1.05\times 10^{-8}\) & x & Module failure & 100\% & x & SM\({}_{\_}{\_}{\_}{\tau=1}\) & 99\% & \(2.6\times 10^{-10}\) & x & SM\({}_{\_}{\_}{\tau=1}\) & 90\% & \(2.57\times 10^{-10}\) \\ EEMke pedal & \(2.6\times 10^{-8}\) & x & Module failure & 100\% & x & SM\({}_{\_}{\_}{\tau=1}\) & 90\% & \(1.05\times 10^{-9}\) & x & SM\({}_{\_}{\tau=1}\) & 99\% & \(9.45\times 10^{-10}\) \\ Radar & \(5.3\times 10^{-8}\) & x & Module failure & 100\% & x & SM\({}_{\_}{\tau=1}\) & 99\% & \(5.3\times 10^{-10}\) & x & SM\({}_{\_}{\tau=1}\) & 99\% & \(5.25\times 10^{-10}\) \\ Radar ECU & \(1.05\times 10^{-8}\) & x & Module failure & 100\% & x & SM\({}_{\_}{\tau=1}\) & 90\% & \(1.05\times 10^{-9}\) & x & SM\({}_{\_}{\tau=1}\) & 99\% & \(9.45\times 10^{-10}\) \\ Speed sensor & \(2.5\times 10^{-8}\) & x & Module failure & 100\% & x & SM\({}_{\_}{\tau=1}\) & 90\% & \(2.6\times 10^{-9}\) & x & SM\({}_{\_}{\tau=1}\) & 99\% & \(2.34\times 10^{-10}\) \\ Speed Meter & \(1.05\times 10^{-8}\) & x & Module failure & 100\% & x & SM\({}_{\_}{\tau=1}\) & 90\% & \(1.05\times 10^{-9}\) & x & SM\({}_{\_}{\tau=1}\) & 99\% & \(9.45\times 10^{-11}\) \\ ECU & \(1.05\times 10^{-8}\) & x & Module failure & 100\% & x & SM\({}_{\_}{\tau=1}\) & 99\% & \(2.00\times 10^{-10}\) & x & SM\({}_{\_}{\tau=1}\) & 99\% & \(1.98\times 10^{-11}\) \\ Power supply & \(2.0\times 10^{-8}\) & x & Module failure & 100\% & x & SM\({}_{\_}{\tau=1}\) & 99\% & \(2.00\times 10^{-10}\) & x & SM\({}_{\_}{\tau=1}\) & 99\% & \(1.98\times 10^{-11}\) \\ Total & \(3.76\times 10^{-4}\) & & & & & & & \(6.56\times 10^{-9}\) & & & & \(3.02\times 10^{-9}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 15: FMEDA report for the AEB system with ASIL D safety goal. Figure 9: Resulting fault tree for the AEB system hardware architecture in compliance with ASIL D and the hardware overhead constraint. been demonstrated so only a limited number of design iterations is required to achieve a cost-effective and reliable hardware architecture that complies with the ASIL safety goal and hardware overhead constraint simultaneously. ## 6 Conclusions and Future Works

In this study, we focus on the design of safety-critical automotive systems, and especially consider the metrics of ASIL safety goal and hardware overhead constraint together in the development process. A safety-oriented system hardware architecture exploration framework is proposed to tackle the complexity of the safety-critical automotive system design. The core of the framework consists of three phases, namely FTA-based weak-point analysis, an ASIL-oriented hardware architecture exploration algorithm, and an HO-oriented hardware architecture exploration algorithm. The main contributions of this work are the development of the ASIL-oriented and HO-oriented hardware architecture exploration algorithms to rapidly discover a cost-effective and robust hardware architecture, which satisfies the target ASIL represented by three hardware architecture metrics, SPFM, LFM, and PMHF, defined in ISO-26262, and the system hardware overhead constraint at the same time. The second is to illustrate how to accomplish hardware architecture exploration for the AEB system to comply with the requirements of the ISO-26262 functional safety standard and hardware overhead constraint.