Driver Vehicle Interface (DVI) Message Priority and Presentation
This SAE Recommended Practice applies to both Original Equipment Manufacturer (OEM) and aftermarket message-generating systems for light and heavy vehicles. The recommended practice covers both message prioritization and presentation (including simultaneous display of messages) for visual and auditory modalities. In addition, this recommended practice will consider temporal aspects of external events (e.g. merging into heavy traffic, time-to-collision) and their impact on temporal presentation and format (including multi-modal) of messages.
Rationale: Currently, there is no industry standard adequately addressing how to prioritize and present (i.e., render) all communications messages between the driver and machine-based systems that come through the Driver-Vehicle Interface.
Prioritization is dealt with to a limited extent by some standards, but none address all the following key aspects needed to be effective.
First, messages come from a diverse set of subsystems. Subsystems can range from tightly integrated vehicle subsystems (e.g. Safety, Vehicle Control, Infotainment) to external subsystems that communicate with the integrated vehicle cockpit (e.g., downloaded 3rd party apps, mobile phones, cloud-based apps, etc.). The different subsystems need to be able to speak a common language to enable things like an externally-generated safety message taking priority over non-safety messages coming from the infotainment system.
Second, there will be future apps and messages not known at the time of manufacture of the vehicle cockpit. This limits the effectiveness of current prioritization schemes based on the assumption that all message types are known and can be rank-ordered at the time of manufacture.
Third, sometimes prioritization should manifest itself by modifying the form of simultaneously played messages. For example, instead of changing the sequential order of audio prompts, two audio prompts could be combined and played at the same time using different techniques to reflect their relative priority. Another limitation of some current standards is that they do not adequately address simultaneous presentation.
Fourth, optimizing presentation modalities and information coding (e.g., verbal prompt vs. non-verbal auditory icon). No real guidance is given in existing standards on how to select the most appropriate message modalities based on message priority, message attributes (e.g., Safety Relevance, Operational Relevance, Time Frame Levels, etc.), and the factors described in the next paragraph. Similarly, there is no real guidance on how to select the most appropriate information coding for a given message and modality for the various scenarios in which they can occur.
Fifth, there are several factors in addition to safety relevance, operational relevance, and timeframe that can change how messages should get prioritized and presented. These include:
• User vs. system initiated interactions
• Message capabilities
o Available message content types
o DVI capabilities (e.g., screen type, etc.)
• Environmental/roadway conditions
• Driver capabilities
• Vehicle state
• Concurrent tasks