In-Cabin Human Machine Interfaces (HMIs) are rapidly evolving, driven by safety, user experience, autonomous driving, technology, regulation, and innovation. This dynamic landscape presents both opportunities and challenges.
Functional safety is one of the primary drivers. Regulatory bodies are pushing stricter standards for complex vehicle systems. This is evidenced by initiatives like Euro NCAP's focus on Driver Monitoring Systems (DMS), with plans to incentivize systems detecting impaired and distracted driving, and the National Highway Traffic Safety Administration's (NHTSA) consideration of Advanced Notice of Proposed Rulemaking (ANPR) regarding driver monitoring to address driver engagement issues. These systems will trigger actions like adjusting ADAS sensitivity or initiating evasive maneuvers. Euro NCAP's phased approach, emphasizing reliable driver status detection, and NHTSA's exploration of driver engagement metrics highlight DMS’s increasing importance.
[Ref: ANPRM: Advanced Impaired Driving Prevention Technology, Euro NCAP Assessment Protocol - SA Safe Driving - v10.3]
This safety focus reveals limitations of traditional QM display solutions, particularly for vehicle clusters. As safety-critical applications increase, display demands grow. Traditional solutions struggle with these requirements, necessitating more robust display technologies.
SAE Level-3 (L3) autonomy amplifies HMIs' critical role. With SAE Level-3 vehicle automation, drivers can relinquish control but must be ready to resume it seamlessly. This hand-over requires clear, intuitive HMI cues. The HMI must provide timely, unambiguous information about the vehicle's state, environment, and driver response. Ambiguity has serious safety implications. Robust HMIs are paramount for safe SAE Level-3 deployment. They must ensure driver engagement, even when not actively driving, requiring innovative solutions beyond simple alerts, potentially including haptic feedback, contextual information, and personalized profiles.
In-cabin HMI evolution is a fundamental shift towards integrated, proactive vehicle safety. By leveraging advanced technologies and adhering to functional safety standards, the industry is building a future where human-vehicle interaction is seamless, intuitive, and safe. This requires a concerted effort from all stakeholders.
Architecting Application Processors for one such key HMI constituent - DMS
Let's explore architecting application processors for evolving in-cabin HMI requirements, using DMS as a case study, emphasizing functional safety.
What is a Driver Monitoring System or in short DMS?
A DMS monitors driver behavior, alerting the driver and/or system to distractions or fatigue. It continuously monitors alertness and detects drowsiness, using reliable eye-tracking and gaze detection. Beyond alertness, a DMS can identify drivers for personalized settings. Critically, it ensures real-time sensor data processing for timely warnings.
We will focus on functional safety aspects of DMS implementation. While direct control of safety-critical ECUs (e.g., Level 2/3 autonomous driving) is outside our scope, the principles discussed can be extended. We focus on the DMS as a standalone warning system, acknowledging future integration potential. This allows us to address specific functional safety challenges within the DMS.
Driver Monitoring System Functional Safety Concept
Our functional safety concept for a DMS outlines the information flow and ASILs. The process begins with image acquisition [ASIL-B] and transmission [ASIL-B]. Image processing [ASIL-B] determines driver state, analyzing for distraction, fatigue, etc. The processed information is transmitted [ASIL-B]. The DMS may warn the driver [ASIL-A/B] and/or notify other systems/take action, such as adjusting ADAS or initiating a controlled stop.
[Note: The ASIL levels presented are for illustrative purposes only. Actual ASIL requirements may vary depending on the specific implementation and context of DMS usage within the ADAS/AD system.]
DMS Functional Requirements and ASIL Considerations
Let’s look at DMS functional requirements and ASIL considerations, emphasizing safety. The DMS workflow starts with image acquisition (camera, resolution, frame rate, field of view). Transmission is secure, with sufficient bandwidth and minimal latency. Image processing (machine learning, e.g., CNNs, LSTMs) determines driver state. Accuracy and processing time are critical. The DMS can warn the driver (audio/graphical alerts) and notify other systems/trigger vehicle actions (e.g., ADAS adjustments). ASIL considerations: Image acquisition/warnings [ASIL-B]; image processing/notification [ASIL-B/ASIL-B(C)]; ADAS/Autonomous System Intervention [ASIL-C/D).
[Note: The ASIL levels presented are for illustrative purposes only. Actual ASIL requirements may vary depending on the specific implementation and context of DMS usage within the ADAS/AD system.]
DMS Technical Concept
Let’s explore the DMS technical concept, focusing on key elements. Performance requirements (image resolution, frame rate, processing speed, accuracy, response time) must align with system goals and ASIL levels. Efficient DMS design balances performance, power, and die area. Scalability and flexibility are essential. Functional safety requires a robust concept addressing potential hazards (ASIL-B for camera/HMI SoC, ASIL-C/D for ADAS/AD interface, ASIL-A/B for display/audio). Hardware/software safety mechanisms (redundancy, error detection, runtime monitoring) are combined. OS choice balances performance and safety (RTOS for performance, safety-certified OS for safety). The diagram suggests a separation between HMI SoC (Sense) and ADAS/AD unit (Plan, Act). These elements enable a robust and efficient DMS.
[Note: The ASIL levels presented are for illustrative purposes only. Actual ASIL requirements may vary depending on the specific implementation and context of DMS usage within the ADAS/AD system.]
Conclusion: Shaping the Future of In-Cabin HMIs
The evolution of in-cabin HMIs is driven by increasing safety demands, enhanced user experience, autonomous driving, technological advancements, evolving regulations, and innovation. This landscape presents both opportunities and challenges.
The journey toward sophisticated and safer HMIs requires a holistic approach, from technical concepts to functional safety. The DMS exemplifies the complexities involved. From image acquisition to system interventions, each stage demands attention to performance, reliability, and safety.
Accelerated execution is crucial. Optimizing chip execution and performance through integrated system-to-silicon design, prioritizing functional safety, is paramount. This necessitates collaborative innovation across the automotive ecosystem, driving the development of highly integrated and efficient processing solutions such as those found in NXP's i.MX processor family. Future-proofing HMIs depends on this collaboration, rigorous testing, and continuous improvement, leveraging advanced architectures designed specifically for the rigors of automotive applications.
Functional safety is paramount. Adhering to standards such as ISO 26262, SOTIF, and ASIL compliance is essential for next-generation HMIs. This focus on safety must be embedded throughout the product development lifecycle. Furthermore, as artificial intelligence becomes increasingly integral to HMI functionality, ensuring its safe and reliable operation is critical. Addressing the unique safety challenges posed by AI, through adherence to emerging standards such as ISO PAS 8800 for safe AI, will be essential for building trust and ensuring the overall safety of these advanced systems.
Scalability and reliability are essential for long-term HMI success. Adapting to new requirements, integrating with other vehicle systems, and maintaining reliable performance are critical.
The future of in-cabin HMIs is bright, transforming the driving experience and enhancing safety. By embracing innovation, prioritizing functional safety, and fostering collaboration, the industry can unlock HMIs' potential and pave the way for a safer, more connected driving future.