Reducing driver fatigue with ADAS
Project Summary:
A new feature was added to the lane centering system that allows drivers to select an offset from the center of the lane. I designed an interaction pattern that allowed us to add the feature without any changes to the already frozen hardware.
Lane bias selection needs to be simple
When operating a semitruck on the highway, it is common for drivers to bias the vehicle closer to the edge of the road than the lane next to them. This is likely to make a standard lane centering system undesirable, so a feature was added to allow the driver to select from 4 lane bias settings: centered, right, left, and automatic (camera detects lane types and system selects).
Long haul truck drivers are on the road long hours and at risk for cognitive fatigue. The lane centering system is intended as a driver comfort feature. Providing a simple strategy for changing the lane bias offset allows drivers the chance to utilize lane centering for more of their drive to reduce fatigue.
My role in the project:
As the HMI Lead for this feature, I worked with the ADAS Chief Engineer, Lane Centering Feature owner, and the software engineers to develop an interaction pattern that is intuitive for drivers and aligned with program objectives.
Empathizing with jobs-to-be-done framework
When driving on long highway stretches, I want to have the vehicle control the steering so that I can relax.
As a long-haul truck driver, I want to select where the vehicle is within my lane so that the system holds the vehicle where it would be if I were controlling the steering.
When I am passing a vehicle, I want to quickly change the lane bias setting so that I can continue using lane centering system while allowing the maximum space between my truck and the vehicle I'm passing.
Physical control finalized prior to the addition of lane biasing
The bias selection feature was added scope for the program and was approved for development after the hardware freeze date. This meant that the HMI strategy would need to leverage the existing center stable three position momentary switch or add the feature setting into a menu in the 5“ driver display.
Placing the lane bias selection into a menu would involve at least three button clicks to change the bias setting. This would add to the complexity, increase eyes off the road time, and likely reduce the usage of the overall lane centering system.
The physical switch requires multiple presses to navigate between the lane bias settings, but it keeps all control functionality in one switch. This was supplemented by temporarily displaying the selected bias setting on the digital display.
New requirements built upon existing interaction patterns
Since the lane bias selection portion of the feature was added late, the original interaction pattern only accounted for enabling and disabling the lane centering system. This meant that a simple momentary up/down toggle switch was selected and needed
Originally, the momentary switch simply enabled and disabled the switch. For the new feature, we wanted to maintain the existing interaction pattern. The option to cycle between the the lane bias selection was added by toggling the switch to the down position. I defined the strategy and wrote requirements which included this flow diagram to visualize the HMI requirements for the implementation teams.
Visual aids were added to the cluster display
Since the control only has 3 positions it can’t indicate the selected lane bias setting, to account for this two types of visual information were added in the display.
A lane bias selection window appears when lane centering is activated and any time the lane bias setting is changed. It serves as information on which position is selected. And the hope is that by showing the window drivers will realize that there are more lane bias settings even though the physical control can't display this functionality. This window will time out once a lane bias setting has been selected.
When the lane centering feature is active, there is a constant visual indicator on the 5” digital display. This symbol was updated to include 4 variations to communicate the active bias setting.
Project Takeaways
Having been the feature owner for lane centering when working on the ADAS team, I experienced the value in understanding the intricacies of feature functionality prior to designing interaction patterns.
Building modular concepts will be increasingly important as more technology features are available that don't require hardware changes. We optimized this solution based on constraints, but if there were more flexibility of system interaction patterns and screen layouts the user experience could have been better.
Collaboration with implementation teams is critical throughout the process. Initially, they provided feedback on implementation feasibility, later they drove HMI requirement updates to specify between where "actual" and driver "requested" states are shown.