Adaptive Safety Warning Countermeasures for Vehicles

1. SAfety VEhicles using adaptive Interface Technology Phase 1 Research ProgramQuarterly Program Review Task 9: Safety Warning Countermeasures Matthew Smith Aug 12, 2003

2. Task description • Team Members: • Delphi: Matthew Smith (Lead), Harry Zhang • Ford: Ksenia Kozac, Jeff Greenberg • Objective: • Enhance safety warning countermeasures to adaptively respond to distraction, gaze, demand, and intent information, e.g., • Deliver earlier warnings for distracted drivers • Minimize nuisance alerts when the driver is attending on intending a maneuver • Purpose: • Improve system effectiveness and driver acceptance of safety warning countermeasures and support the evaluation of adaptive enhancements • Reducing false alarms may increase the credibility of the warnings so that they are less likely to be ignored • Earlier warnings for distracted drivers may reduce the number of collisions

3. Deliverables and Schedule • Deliverables: • Task 9A: A report based on the literature review and updated task definition document • Task 9B: A report that specifies the adaptive enhancements to the countermeasures, describes the research conducted to reach the provided specification, and proposes preliminary guidelines and standards (to be reviewed in Task 12) • Schedule: • 9A: Literature Review • First draft of literature review is complete • First draft currently under internal Delphi review before external circulation • 9B: Identify Adaptive Countermeasures • Identified Countermeasure Systems • Identified Adaptive Enhancement Issues • Defined and Described Potential Adaptive Enhancements • Selected and coded FCW algorithm • Selected FCW DVI • Preliminary Design BRT Study complete

4. Literature Review: Task 9a • Research Areas of Interest / Literature Review Sections • 9.1 INTRODUCTION • 9.2 CRASH CLASSIFICATION AND THE ASSOCIATED SAFETY WARNING COUNTERMEASURES • 9.3 FORWARD COLLISION WARNING (FCW) • 9.4 LANE DRIFT WARNING (LDW) • 9.5 STOP SIGN VIOLATION WARNING (SSVW) • 9.6 BLIND SPOT WARNING (BSW) • 9.7 ADAPTIVE ENHANCEMENTS • 9.8 CONCLUSIONS • Ford may be adding a short Curve Speed Warning (CSW) section • Key Source Material • Collision Types (Najm, Sen, Smith, & Campbell, 2003) • Rear-end crashes and countermeasures (Burgett, Carter, Miller, Najm, & Smith, 1998; Knipling, Hendricks, Koziol, Allen, Tijerina, & Wilson, 1992; ACAS FOT reports, 2002-2003) • Lane change crashes and countermeasures (Chovan, Tijerina, Alexander, Hendricks, 1994; Tijerina, & Hetrick, 1997) • Intersections crashes and countermeasures (Pierowicz, Jocoy, Lloyd, Bittner, Pirson, 2000) • SVRD crashes and countermeasures (Pomerleau, Jochem, Thorpe, Batavia, Pape, Hadden, McMillan, Brown, and Everson, 1999)

5. Task 9a: Literature ReviewMajor Findings Police-Reported Light Vehicle Crashes (Najm, Sen, Smith, & Campbell, 2003) Roadway Fatalities (U.S. Department of Transportation, 1997)

6. Task 9a: Literature ReviewMajor Findings (cont.) • Rear-end Crashes • Most prevalent category of crashes • Knipling et al. (1992) estimated that over ¾ of rear-end collisions involve driver inattention (including inattentive and following too closely) • Forward Collision Warning (FCW) systems are designed to prevent RE collisions but from the ACAS FOT program appear to have high nuisance alert rates • Many participants complained that the warnings are too late if they are not attentive and unnecessary when they are attentive • Road departure Crashes • Largest cause of roadway fatalities (36%) • Mironer and Hendricks (1994) estimated 9% of SVRD involve driver inattention to lane keeping (25% to driver impairment) • Lane Drift Warning (LDW) designed to prevent unintentional lane departure • Curve Speed Warning (CSW) designed to prevent roadway departures caused by excessive speed on curved road segments

7. Task 9a: Literature ReviewMajor Findings (cont.) • Intersection Crashes • Second most prevalent category of crashes • Different countermeasures for different types of accidents (Pierwowicz et al., 2000) • Most sub-categories of intersection crashes require infrastructure support • Stop-sign violation warning (SSVW) involves simple sensor requirements and can target 18% of all intersection accidents • Lane Change/ Merge Crashes • 9% of collisions and 1% of fatalities • Wang et al. (1996) estimated 5.6% attributed to driver distraction and 17.2% to Looked-but-did-not-see (LBDNS) • Many blind-spot warning systems have emerged on the market • Many researchers suggest activating higher-levels of warning using the turn signal or some other indication of driver intention

8. Task 9a: Literature Review Countermeasure Systems • Forward Collision Warning (FCW) • Strong relationship to driver distraction • Problematic nuisance alerts • Task 9 (SWC) will investigate FCW • Lane Drift Warning (LDW) • Problematic nuisance alerts (e.g., intentional lane changes) • Task 9 (SWC) task likely to investigate LDW • If not feasible for SAVE-IT on-road testing/prototype vehicle it may still be feasible in driving simulator analyses • Curve Speed Warning (CSW) • Can develop relatively simple system with GPS/Map matching • Ford is currently considering supporting this activity for SAVE-IT • Stop Sign Violation Warning (SSVW) • Simple system • Task 9 (SWC) likely to investigate SSVW • Blind Spot Warning (BSW) • Difficult to evaluate in single-channel driving simulator in Phase I

9. Task 9a: Literature Review Forward Collision Warning (FCW) • Algorithm Alternatives • Time-headway • Time-to-collision • Kinematic Constraints • Calculates minimum range to avoid collision by braking at specified rate after a specified reaction time • Most comprehensive algorithm • Driver Vehicle Interface

10. Task 9a: Literature Review Lane Drift Warning (LDW) • Algorithm Alternatives • Zero-order Time-to-Line crossing (TLC) • Simple but doesn’t consider rate of drift • First-order TLC • Assumes lateral acceleration will remain constant • Second-order TLC • Use of acceleration amplifies measurement error • Kinematic TLC • Takes into account upcoming road geometry • More complex measurement requirements • Driver Vehicle Interface • Steering-wheel counterforce • Tijerina et al. (1996) recommended not using both auditory and haptic

11. Task 9a: Literature Review Stop Sign Violation Warning (SSVW) • Pierowicz et al. (2000) used required deceleration to prevent intersection entry as the criterion for the warning • If required deceleration (ap) exceeds 0.35 g warn the driver • System only requires GPS signal and a digital map to determine the distance to the intersection • Driver Vehicle Interface • Pierowicz et al. (2000) used a stop-sign symbol on a HUD

12. Task 9a: Literature Review Blind Spot Warning (BSW) • Tijerina and Hetrick (1997) suggested three stages of warning • Stage 1: object in blind spot • Suggested using visual-only stimulus • Stage 2: object in blind spot and turn signal is activated • Suggested using “augmented” visual-only stimulus (e.g., flashing visual) • Stage 3: object in blind spot and host vehicle moving toward blind spot • Suggested using multi-modality (e.g., visual plus haptic or auditory) • Driver Vehicle Interface

13. Task 9a: Literature Review Adaptive Enhancement Issues • Provide appropriate level of adaptive enhancement • Not over-sensitive so that it changes too frequently or appears to be unstable • Not under-sensitive so that it is non-responsive, providing little added value • Avoid closed-loop oscillations or impressions of system inconsistency • e.g., • Billings (1997) argued that the adaptation must be predictable so the user can from a clear mental model of the system’s behavior Attentive Inattentive

14. Research: Task 9b • Research Objectives/Strategy • Countermeasures usually involve imminent alert levels and must predict how quickly the driver must react to the alert • Determine how the results from the other experiments can be mapped onto adaptive enhancements to the countermeasures • Experiment 1: Imminent Alerted Brake Reaction Time (BRT) • Determine the effectiveness of different adaptive enhancements • Experiment 2: Comparison of Different Adaptive Enhancements • Experiment 1 Method • Measure BRT to the FCW alert as a function of different levels of distraction • Manipulate distraction level in the driving simulator using conditions from Tasks 5 (Cognitive Distraction) and Task 7 (Visual Distraction) • Lead vehicle brakes suddenly at an imminent level (e.g., 0.5 g) • Experiment 2 Method • Expose subjects to different implementations of enhanced countermeasure systems during differing levels of imposed driver distraction • Assess the driver acceptance issues surrounding adaptive enhancements (e.g., should alerts be delayed or suppressed completely when the driver is attentive?)

15. Research: Task 9b Experiment 1: Imminent Alerted BRT • Variables • Independent Variable: Distraction Level • Dependent Variable Brake Reaction Time (BRT) • Facilities/Apparatus/Subjects • Delphi Driving Simulator • Between-subject study • Can only surprise subjects once • 10-12 subjects per condition (50-60 total) • Subjects in 35 – 55 age group • Distraction Level Conditions • No distraction with alert • Mid-level cognitive distraction (from Task 5) with alert • High-level cognitive distraction (from Task 5) with alert • Mid-level visual distraction (from Task 7) with alert • High-level visual distraction (from Task 7) with alert

16. Research: Task 9b Experiment 2: Adaptive Enhancements • Variables • Independent Variables • Countermeasure System / Adaptive enhancement concept alternatives • Distraction Level • Dependent Variables • Subjective responses regarding the enhancement alternatives (driver acceptance) • Observe different adaptive enhancements with different drivers • Facilities/Apparatus/Subjects • Delphi Driving Simulator • Use subset (10 – 24) of participants recruited from the reaction time experiment • Likely use the high-level visual and/or cognitive distraction group because they are likely to be familiar with the concept of driver distraction in relation to collision warnings • Design • Instruct participants to drive in the simulator while engaging in the distraction tasks and experiencing the adaptive enhancements • Lead vehicle will frequently brake to assess adaptively-enhanced FCW • Compare different types of adaptive countermeasures and non-adaptive countermeasures

17. Research: Task 9b Issues/Concerns • IRB approval • IRB approval (August 29th) may be delayed to allow more accurate and detailed submission (changes less likely) • Iteratively test and refine countermeasure concepts • Deadline of August 29th not feasible because Delphi driving simulator will not be available for development until early September (Used in Task 7) • Estimated completion October 17th • Facility Preparation • Deadline of August 29th not feasible because Delphi driving simulator will not be available for preparation until early September • Estimated completion October 17th • Design Adaptive Concept test study • Initial deadline of July 31st not feasible because of driving simulator delay • Estimated completion September 30th • Data Collection • Deadline of November 3rd not feasible because of delay in facility preparation • Estimated completion November 28th • Data Analysis, Final Report, and Phase II plan • Respective deadlines of Jan 5th, Jan 30th, and Feb 27th should still be possible