An advanced driving simulator equipped with an Adaptive Cruise Control (ACC) system was used to study driving behavior of drivers with lower limb impairments. The ACC system could keep a constant speed selected and set by the driver and also adapt speed in order to keep a safe distance to a leading vehicle. The purpose of the study was to investigate ACC driving influence on workload, comfort and driving behavior compared to manual driving. Twenty subjects with leg impairments, all experienced drivers of converted cars, participated in the study. Two common types of hand controls for accelerator and brakes were used for the manual driving condition. These were different both with respect to function and position. All subjects drove 100 km at two occasions, with and without the ACC system available. Subjective workload was found to be lower and performance better when ACC was used. Manual speedkeeping is a loading task and increased variation in speed could indicate increased load or tiredness. The difference in speed variation between manual and ACC supported driving increased with the distance driven. The subjects thought they could control both speed and distance to leading vehicles better while driving with the ACC. ACC driving did not influence reaction time, speed level, lateral position or variation in lateral position. Headway during car following situations was shorter for the ACC condition compared to manual driving. The ACC was well received, trusted and wanted. It was concluded that the ACC system substantially contributed to decreased workload and increased comfort for drivers with lower limb disorders. For the covering abstract see IRRD 897155.
Abstract