Using an automated speed, steering, and gap control system and a collision warning system when driving in clear visibility and in fog

Abstract

The effect on driving performance of using a speed, steering, and gap control system (SSGCS) and a collision warning system (CWS) was assessed in an experiment conducted in the Iowa Driving Simulator. Driving performance data were obtained from 52 drivers, 32 of whom drove with both systems and 20 controls who did not have access to either. Results were as follows: (1) Driving while using the SSGCS: When the driver was using the SSGCS, there was no effect on speed; however, the driver's car tended to follow further behind the vehicle ahead than did the control-group drivers. (2) Driving while using only the CWS: With the CWS engaged, drivers controlled both the speed and the steering more precisely than the control-group drivers. This may have occurred because the driver was paying more attention than normal to the driving task. When using the CWS alone, the driver's speed was greater than that of the control drivers--particularly in the 100-m (328-ft) fog. This may have occurred because the driver was testing the CWS. Use of the CWS alone had no effect on the following-distance measures. (3) Driving when the SSGCS and CWS were disengaged: When the driving performance of the experimental-group drivers, with both intelligent systems disengaged after the SSGCS had been activated at least once, was compared with that of the control-group drivers on steering instability, average velocity, and average actual gap, the results were mixed. There was no difference in minimum following distance between the experimental- and control-group drivers. The experimental-group drivers had more steering oscillations, making steering correction movements more frequently than the controls, but without changing their steering instability. They also reduced their velocity instability while increasing the number of velocity fluctuations. They were controlling speed more precisely than the controls, making more frequent corrections of smaller amplitude than the controls. These changes in driving performance may have occurred because the driver had to decide whether, and when, to use the SSGCS and CWS, and may have been paying much more attention than normal to the task of driving.