In this project, the steering wheel evolves from a classic input device to a tangible interactive system in the modern sense. It keeps its well-proven passive direction control function, but it is now extended to an active and dynamic component of the vehicle with integrated measurement, calculation and feedback functionalities.
The main measurement function is the detection of the presence, quantity, location and grip pressure of human hands on the steering wheel. In combination with an integrated algorithm, the system can spot safety critical scenarios in regards to the driver’s control of the steering wheel. Detected hazards can cause direct feedback via visual (multicolor LEDs), audible (horn, bell, buzzer) or even tactile (vibration) output elements, which are also part of the steering wheel system. As an added option, the information can be sent to an external autonomous driving system, which could initiate a safe stopping procedure of the vehicle.
The core of the solution is a capacitive sensor system which is integrated in the steering wheel.
My task in this project was to design and model a framework of such a steering wheel system as the basis for continuative model-based systems engineering. I modelled the system architecture with IBM Rational Rhapsody in two views:
- Functional view (e.g. hands-off raw data provision, hands-off data evaluation, system state machine, error management, power supply management, on-board communication)
- Structural view (e.g. capacitors, cables, hardware units, software modules, steering wheel mechanics, temperature sensor, interaction components)
The model covered also many other aspects of the system:
- Closed loop control of the capacitive sensors
- Capacitor loading and measurement sequence
- Status and team management
- Allocation of system requirements to model elements
- System context
- SysML profile related to the field
- Safety analysis according to ISO 26262
The comprehensive system model supported many of the advantages of model-based systems engineering such as developer-in-the-loop project organization, centralized system definition, integrated agile requirements management and directly supported ASPICE compliance.