KOSTAL Asia R&D Center Receives ISO 26262 ASIL D Certification for Automotive Software Developed with Model-Based Design

An automotive ESCL prevents theft by locking the steering wheel when the vehicle is parked. Because of the dangers such a system could cause if it erroneously locked the wheel while the car was moving, ESCL software must be developed to ISO 26262 ASIL D, the highest functional safety standard.

To achieve this goal, KOSTAL needed to fulfill all ISO 26262 ASIL D requirements, including the verification of software via back-to-back testing that includes software-in-the-loop (SIL) and processor-in-the-loop (PIL) tests on the automatically generated code. KOSTAL engineers needed support to rapidly establish the necessary framework.

KOSTAL used Model-Based Design with MATLAB^® and Simulink^® to develop the ESCL application software and certify it to ISO 26262 ASIL D.

The company worked with MathWorks engineers to establish a PIL testing framework and to provide training to software development team members who were new to Model-Based Design.

Working in Simulink and Stateflow^®, KOSTAL engineers developed a model of the ESCL software application layer, which included a finite state machine to define the sequential decision logic.

The group created modeling standards based on MathWorks Automotive Advisory Board (MAAB) guidelines and used Simulink Check™ to ensure that their model complied with the standards.

They ran simulations in Simulink to verify the functionality of the design, and used Simulink Coverage™ to measure model coverage of the functional tests.

Using Simulink Design Verifier™ they applied formal methods to identify dead logic and other design errors in the model.

The engineers generated C code from the ESCL model using Embedded Coder^®. They used Polyspace Code Prover™ and Polyspace Bug Finder™ to check the generated code and handwritten code for run-time errors.

They then ran back-to-back PIL tests using the generated code and compared the test results in MATLAB.

To streamline the certification process, the engineers used IEC Certification Kit for ISO 26262 and IEC 61508. They qualified several tools for certification, including Embedded Coder, Simulink Coverage, Polyspace Bug Finder, and Polyspace Code Prover.

The ESCL is ISO 26262 ASIL D certified and has been approved for production by one of the largest car manufacturers in China. Model-Based Design is now the preferred approach for projects requiring functional safety certification at KOSTAL.

• Development and certification time cut by 30%. “Without Model-Based Design, we would have needed at least 30% more time to develop and certify the ESCL application software,” says Hui. “We saved time and effort by generating efficient code that satisfied all our speed and memory requirements.”
• 80% of errors identified in modeling phase. “Using Model-Based Design, we identified and resolved 80% of logic and functional errors in the model development and simulation phase,” Hui says. “This early verification, combined with Polyspace static analysis, saved considerable validation and testing effort.”
• PIL test framework for ISO 26262 established. “We use Model-Based Design for the application software. According to ISO 26262, the automatically generated code should be tested using PIL. MathWorks engineers provided us with exceptional support in establishing a back-to-back PIL testing framework,” says Hui. “That framework was instrumental in our ability to achieve ISO 26262 certification on schedule.”