Carsten Semmler

The “HMI tool kit” as a Strategy for the Systematic Derivation of User-Oriented HMI Concepts of Driver Assistance Systems in Urban Areas

The development of driver assistance systems has shown various innovation waves in the last few decades. While such systems can contribute to increasing driving safety and comfort on highways and rural roads, future systems will be enhanced to include urban traffic. Such trends also face challenges, especially in the design of human-machine-interfaces (HMIs). In the UR:BAN project, one aim was to design user-oriented, integrative HMI concepts of current and future assistance systems by considering the challenges of urban driving. Therefore, the cross-functional “HMI tool kit” was developed comprising a strategy for the systematic derivation of action-oriented HMI concepts. The structure of the HMI tool kit differentiates between cases of applications for safe, comfortable, and energy-efficient driving, which takes requirements of different time horizon and user-actions into account. The HMI tool kit provides insight into 1) how information, warnings, and system interventions should be filtered and prioritized to the driver concerning the current traffic situation and 2) how the preferred driver behaviour can be achieved in the situation by the selection of suitable HMI components (e.g. display in the instrument cluster, warnings or sounds). The aim is to warn the driver adequately in safety-critical situations and allow him to develop a sufficient understanding for continuous system interventions or advanced navigation recommendations. The UR:BAN HMI concepts can contribute to an anticipatory driving style, to mitigate safety-critical situations, and to improve stress-free and low-emission driving in urban traffic.

HMI Strategy – Warnings and Interventions

One of the most important aims of driver assistance systems is the prevention of accidents. Onboard-sensors, algorithms, and other technologies allow developing strategies to achieve this, for example by warning drivers in critical situations. Depending on the remaining time, different driver reactions may have to be elicited. In some situations it may be sufficient to slow down well in advance or to change lanes. However, in other situations only an emergency braking or a fast evasive manoeuvre can prevent a collision. Since in most situations drivers are still in control of the car, the question arises of how to best support them in these kinds of situations. This encompasses two basic HMI aspects: (1) How can the required reactions be elicited in drivers, before the system has to intervene automatically due to the increased criticality and reduced time left? In such a very critical situation, (2) how can drivers be explained how and why the assistance system has taken over and intervened? Within the scope of the UR:BAN project, HMI concepts were developed and evaluated with regard to these aspects of intervention and warning strategies. The chapter gives an overview about the conducted studies and resulting HMI concepts.

HMI Strategy – Lateral and Longitudinal Control

Advanced driver assistance systems (ADAS) which continuously intervene in the lateral or longitudinal control of the vehicle can increase the efficiency and comfort while driving. In order to achieve the best possible use of such systems, the HMI has to be adapted to the driver’s needs and capabilities. The current chapter describes how two HMI concepts for urban traffic were developed and refined based on the driver’s demands: (1) a truck-specific HMI strategy for an automated longitudinal control and (2) a HMI strategy for a lateral control system on narrow roads – the constriction assistant. In both cases, the essential components of the HMI were identified using several methods, e.g. accompanying truck drivers in daily traffic, driving simulator studies, and integrated into an HMI strategy.