Effects of Task-Induced Fatigue in Prolonged Conditional Automated Driving.

OBJECTIVE: The aim of this study was to investigate the effects of task-induced fatigue in prolonged conditional automated driving on takeover performance. BACKGROUND: In conditional automated driving, the driver can engage in non-driving related tasks (NDRTs) and does not have to monitor the system and the driving environment. In the event that the system hits its limits, the human driver must regain control of the car. To ensure safety, adequate driver fallback performance is necessary. Effects of the drivers' state and the engagement in NDRTs need to be investigated. METHOD: Seventy-three participants experienced prolonged conditional automated rides and simultaneously had to engage in either an activating quiz or a fatiguing monitoring task (between subjects). After 50 minutes, a takeover situation occurred, and participants had to regain control of the car. RESULTS: Prolonged conditional automated driving and simultaneously engaging in NDRTs affected the driver's state and the takeover performance of the participants. Takeover performance was impaired when participants had to deal with monotonous NDRTs. CONCLUSION: An engagement in monotonous monitoring tasks in conditional automated driving affects the driver's state and takeover performance when it comes to takeover situations. Especially in prolonged automated driving, an adequate driver state seems to be necessary for safety reasons. APPLICATION: The results of this study demonstrate that engagement in monotonous NDRTs while driving conditionally automated may negatively affect takeover performance. A monitoring of the driver state and adapted assistance in a takeover situation seems to be a good opportunity to ensure safety.

Expert-based controllability assessment of control transitions from automated to manual driving.

Up to a level of full vehicle automation, drivers will have to be available as a fallback level and take back manual control of the vehicle in case of system limits or failures. Before introducing automated vehicles to the consumer market, the controllability of these control transitions has to be demonstrated. This paper presents a novel procedure for an expert-based controllability assessment of control transitions from automated to manual driving. A standardized rating scheme is developed that allows trained raters to integrate different aspects of driving performance during control transitions (e.g., quality of lateral and longitudinal control, adequateness of signalling to other road users, etc.) into one global controllability measure based on video material of the driving situation. The method is adapted from an existing assessment procedure that has been successfully applied to assess the criticality of driving situations in manual driving conditions (e.g., assessment of substance-induced impairments, assessment of fitness-to-drive of novice drivers). This paper presents the rating procedure, including instructions of how to code relevant qualities of the drivers' performance with accompanying video-demonstrations, and material used for rater training. •A rating procedure for an expert-based controllability assessment of control transitions from automated to manual driving based on observation of video material was adapted from an existing method used in studies on manual driving.•The advantage of this method consists in an integration of different dimensions of driving performance (e.g., operational and tactical driving behaviour, criticality of the situation) into one global controllability measure.•The method allows an assessment and comparison of diverse take-over scenarios, detached from driver performance variables.•The accompanying video-based training material allows reproducible and reliable execution of the rating procedure.

Thermal behavior of [2.1.1]propellane: a DFT/ab initio study.

Density functional and ab initio molecular orbital calculations have been used to search for the low energy path of the thermal isomerization of [2.1.1]propellane 1. Three reaction modes were considered: ring opening of the bicyclo[1.1.0]butane unit in 1 to give 1,2-dimethylenecyclobutane 21, opening of the four-membered ring of 1 to afford 1,3-dimethylenecyclobutane 20, and breaking of the [2.1.1]propellane central bond and one of the bicyclo[1.1.0]butane side bonds to form carbene 17. At the CAS(12,12)PT2N/6-31G(d) level of theory, the activation barrier of the latter route was lowest in energy. Further investigation of this process at the QCISD(T)/6-311G(d,p)//QCISD/6-31G(d) and B3PW91/6-311G(d,p)// B3PW91/6-311G(d,p) level of theory indicated that the barrier of isomerization of 1 --> 17 amounts to 29 kcal/mol and that 17 is stabilized by hydrogen migration to give dienes 18 and 19.