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15 Table 3.4. Physical Assessments (OBD II) so that specific vehicle network data can be obtained. Turn signals are collected from network data as available, or Measurement In Person/ Estimated a cable connection will be established to capture turn-signal Construct Description Online Time (min) usage data. Note that the head unit is actually composed of two Lower limb Rapid Pace Walk In person subassemblies: the rear camera and cellular antenna (General 1 strength/ Packet Radio Service, GPRS), both located on the rear pack- mobility age shelf (or similar location in SUVs and minivans). Upper body Jamar Hand In person 2 The head unit (Figure 3.3) assembly holds three cameras strength Dynamometer that will capture video images as illustrated in Figure 3.4. These image components include the forward roadway (upper left), driver face (upper right), and the pedals and instrument clus- ter interactions (lower left). The area behind and to the right Data Acquisition of the subject vehicle (lower right) will be captured by a sep- System Variables arate camera mounted on the rear of the cabin. Note that The DAS comprises three primary units: the head unit, the the face image is oriented at a 90-degree angle from the other main unit, and the front radar assembly as illustrated in Fig- images to maximize the efficiency of pixel allocation among ure 3.2. Cabling will provide hard-wired connections between all four images. That image and all images will be correctly the head unit and main unit as well as a power source. Addi- oriented before any type of video analysis. Also, another tionally, cabling will connect to the onboard diagnostic port camera, located in the head unit, will periodically take a still Table 3.5. Health-Related Assessments In Person/ Estimated Measurement Construct Description Online Time (min) Sleep quality Harvard sleep questionnaire Online 10 Potentially driver-impairing medical conditions Custom comprehensive questionnaire based Online and medications on material from the American Medical Association (AMA) and National Highway 20 Traffic Safety Administration (NHTSA) Table 3.6. Psychological Assessments In Person/ Estimated Measurement Construct Description Online Time (min) Risk-taking behavior Cox Assessment of Risk Driving Scale (CARDS) Online combined with DeJoy Risk Perception 2 Questionnaire Risk perception CARDS items combined with DeJoy Risk Online 2 Perception Questionnaire Attention deficit hyperactivity disorder (ADHD) Barkley's Adult ADHD Quick Screen Online 2 Driver style/behavior Manchester Driver Behavior Questionnaire (DBQ) Online 5 Thrill/adventure seeking Sensation Seeking Scale (SSS) Online 5 Table 3.7. Driving Knowledge/History Assessments Measurement Construct Description In Person/Online Estimated Time (min) Driving knowledge Custom questionnaire based on several state Online 10 licensing practice tests Driving history Custom questionnaire Online 5
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16 sor, incident button, illuminance sensor, inertial acceleration, and gyroscopic sensors will be incorporated into the head unit assembly. In determining which sensors could be the most valuable, an extensive review of the research questions was conducted. The outcome of that prioritization led to the chosen sensors. The selected sensors reflect the best combination of desir- able data that can be obtained within the cost and engineering constraints of the project and that meet the highest-priority research questions. The main unit (Figure 3.5) is host to the computer functions of coordinating sensor nodes, communications (internally and via the cellular capability), and data storage on the hard drive (HD). It will have the capability of storing data on an onboard Figure 3.1. Optec 6500P all-in-one vision test solid state HD for 4 to 6 months of typical driving. It will fea- apparatus. ture continuous asynchronous data collection. That is, each sensor or variable will be recorded at its native frequency and image of the cabin. These still images will be used to deter- time-stamped with a real-time clock, without regard to the fre- mine the presence of passengers, and they will be irretrievably quency at which any other data are being recorded. This is the blurred to protect the anonymity of unconsented passengers. most efficient approach to dealing with storage limitations. This assembly will be mounted to the right and rear of a par- Vehicle network information is expected to be obtained from ticipant's rearview mirror. The forward camera will capture most of the vehicles for driver control interactions. For some a color image, and the remaining cameras will be low-cost, makes and models, additional advanced technology variables small-form-factor monochromatic cameras that are sensitive are expected to be captured, such as the ABS, ESC, brake assist, to infrared (IR) illumination (for low-light video capture). traction control, etc. This feature requires OEM cooperation The forward camera will collect color video to provide more as described previously. Accelerometers will nominally collect comprehensive information about the forward or driver's X, Y, Z acceleration at 10 Hz, but these data will be continu- view. Furthermore, for those researchers interested in traffic ously buffered at 500 Hz and saved at this higher rate under signal state detection, the color camera will provide the ability certain circumstances to provide higher-resolution accelera- to conduct such research through a post hoc machine appli- tion information during a crash event. Yaw rate gyro will also cation or manual data analysis. Additionally, the alcohol sen- be collected continuously at 10 Hz. Front Turn Head Unit Signals DAS Main Unit Radar Interface Box GPRS Radar Unit Antenna Bluetoo Sub-Head th Unit Rear Camera PWR PWR OBD Connector Figure 3.2. DAS schematic.