Advancing HMI Development of ADAS and Active Safety Systems

May 2, 2024

Nam Nguyen

The advancement of vehicles with enhanced safety and infotainment features has made evaluating human-machine interfaces (HMI) in modern commercial and industrial vehicles crucial. Drivers face a steep learning curve due to the complexities of these new technologies. Additionally, the interaction with advanced driver-assistance systems (ADAS) increases concerns about cognitive impact and driver distraction in both passenger and commercial vehicles.

As vehicles incorporate more automation, many clients are turning to biosensor technology to monitor drivers’ attention and the effects of various systems and interfaces. Utilizing neuroscientific principles and AI, data from eye-tracking, facial expressions and heart rate are informing more effective system and interface design strategies. This approach ensures that automation advancements improve rather than hinder the driving experience.

The integration of HMI systems in vehicle design is evolving rapidly, focusing on enhancing user-vehicle interactions. A deep understanding of human-factors engineering is essential for creating safe, efficient and user-friendly driving experiences. Companies like iMotions and SmartEye are using behavioral research and eye-tracking to pioneer new HMI design principles.

The role of neuroscience in HMI design

Human factors are critical in designing HMIs for transportation systems, with designs needing to accommodate the abilities and limitations of human drivers. This involves ergonomic design, cognitive psychology and user experience (UX) research to develop interfaces that are user-friendly, safe and intuitive.

The aim is to create systems that align with human behavior and cognitive processes, reducing errors and improving usability. Advances in neuroscience have greatly enhanced the tracking, assessment and design of HMIs, moving beyond traditional interview-based methods to more sophisticated, neuroscience-based techniques.

Modern approaches include using camera-based eye trackers like SmartEye Pro, AI-powered facial expression analysis tools like Affdex, and methods like electrodermal response and electrocardiography (ECG), once limited to research labs. These tools are now applied to develop commercial HMI applications, showcasing their relevance and utility in improving system design.

Vehicle HMI design must manage the driver’s cognitive load, the mental effort required in working memory. Human-factors experts aim to design interfaces that simplify information processing, reducing cognitive load to prevent confusion and potential hazards. This involves organizing information logically, minimizing complexity, and using visual and interactive hierarchies to highlight essential functions.

For example, non-essential controls like A/C, music and cruise control are placed on the steering wheel, allowing drivers to use them without looking away from the road. New features added to the dashboard are strategically positioned for safety and ease of use. iMotions software helps measure how long drivers divert their gaze from the road to interact with these tools.

Optimizing user-centric design

Ergonomics play a critical role in HMI design, focusing on the physical interaction between users and vehicle interiors. This includes the strategic placement of controls and displays, ensuring they are easy to operate and provide adequate feedback. A well-executed ergonomic design enhances user comfort and efficiency, reducing the likelihood of strain, errors and accidents. Designing for diverse users involves complex assessments traditionally conducted through iterative testing or focus groups.

The core of this approach lies in user-centered design, which incorporates user feedback from the initial stages to create intuitive and satisfying interfaces. This method helps overcome traditional design challenges like biased or inadequate feedback by using biosensors that record detailed reactions in real time. By capturing these instantaneous responses, developers can discern critical factors that differentiate effective from ineffective designs, leading to better, more user-focused systems.

Human factors in HMI design go beyond just cognitive and physical aspects. They also consider the emotional and psychological impact of interfaces on users. This involves understanding how design elements can affect mood and stress levels and designing interfaces that create positive emotional connections with the user. For instance, the use of color, shape and texture can influence a user’s perception and emotional response to a system. Tools such as driver facial expression monitoring, ECG and muscle tension can provide valuable insights into how drivers and passengers react to the cabin environment that can be improved once the individual elements of form and function are identified.

Safety is paramount in HMI design, where human-factors expertise is crucial for reducing errors and accidents. This requires designing interfaces that are straightforward, predictable and forgiving of user errors. Accessibility is also essential, ensuring interfaces are usable by people of various abilities, including those with disabilities.

Additionally, tools used for measuring user responses are now employed in developing driver monitoring systems. These systems detect states like drowsiness or distraction, helping to mitigate risky driving behaviors and enhance safety. Truck and car companies are increasingly utilizing these technologies to incorporate human-in-the-loop systems that improve overall driving safety.

Emotion analytics and advanced eye-tracking

iMotions specializes in integrating emotion analytics into the HMI design process. The approach aims to understand the emotional and cognitive states of drivers in real time, using advanced sensor technologies to capture data on eye movement, facial expressions and physiological responses. This data-driven approach helps designers recognize how drivers interact with various HMI elements, identifying areas of cognitive overload, distraction or stress.

By utilizing such technology, vehicle designers can make informed decisions about the layout, complexity and functionality of HMI systems. For instance, insights into gaze patterns can inform the optimal placement of critical information on dashboards, ensuring that drivers can access the information they need without diverting attention from the road. Similarly, monitoring physiological responses during interactions with infotainment systems can help in designing interfaces that minimize cognitive strain.

Integrating iMotions’ advanced emotion analytics and biometric sensing within simulators provides insights into drivers’ cognitive loads, emotional states and physiological responses. iMotions Software employs various biometric measurements, including eye movements, facial expressions, heart rate variability and EEG (electroencephalogram) to study how drivers respond to different HMI elements during simulations. This real-time data enriches understanding of driver behavior, helping designers pinpoint which aspects of HMI design enhance intuitive use and which could cause confusion.

The collaboration with Dutch simulator manufacturer Cruden enhances this process, enabling swift evaluations and adjustments. This method is actively used at the University of Michigan Dearborn’s Driving Simulator Lab, for example, to align interfaces more closely with human capabilities.

Advanced eye-tracking technology provided by the multi-camera Smart Eye Pro system allows HMI designers and researchers to accurately monitor where and for how long a driver looks at different areas of the vehicle interior. It also reveals how a driver interacts with the cabin in real time via 3D wireframe modeling without any distracting influence from wearables. This technology is beneficial in the development of adaptive HMI systems that can dynamically adjust based on the driver’s focus.

By combining the strengths of both emotion analytics and eye-tracking technology, and leveraging advanced simulator systems from Cruden, designers can gain a better understanding of the driver’s physical and emotional state. The potential synergy between these technologies holds great promise for the future of HMI design in vehicles.

Nam Nguyen, technical partnership manager and senior neuroscience product specialist for iMotions  , contributed this article for SAE Media.

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