Study on an HMI system to induce appropriate and effective use of BSM at lane changing

Abstract

The installation of Advanced Driving Assistant Systems (ADAS) in vehicles is becoming obligatory in stage. However, it seems that many drivers do not fully understand the functions of ADAS and how to use them appropriately. Therefore, it is necessary to develop HMI systems to promote drivers’ appropriate use of ADAS. In this study, we focused on the Blind Spot Monitoring system (BSM) which indicates an approaching rear vehicle following in the neighboring lane with the indicator when the blinker is put out to change lanes. The system also gives alarm sound to deter lane changes that may cause an accident with the approaching rear vehicle. To improve the deterrence of the BSM against risky lane change, we designed an HMI system to supply information of the BSM by voice guidance and HUD. The effect of the system was verified by experiments and investigations. The HMI system was designed to inform whether the driver may be safe to change lanes, pay attention, or be in danger. We conducted experiments with twenty subjects using a Driving Simulator (DS). On the course of the DS, there were five places to change lanes. At one of them, no information was given to drivers when changing lanes. At two of them, information with an indicator was given by the BSM. At the other two, information via voice guidance and HUD by the HMI system were provided in addition to the BSM. The results of the experiments showed that there was no collision due to lane change made by the subjects ignoring risks when the HMI system activated, whereas there were two collisions (out of forty lane changes by twenty subjects) when the BSM activated only and was one (out of twenty lane changes by twenty subjects) without any information. It is also shown that the alarm of the BSM sounded six times (15%) when the HMI system activated, while it sounded twelve times (30%) when the BSM activated only. Due to the alarm, the subjects gave up changing lanes three times (50%) with the HMI system, while five times (44%) with the BSM only. These results indicate that the HMI system tends to increase deterrent force against risky lane changes. This means that the drivers tend to make safer decisions with a combination of the BSM and the HMI systems than with the BSM only. It is also shown that drivers tend to decrease the vehicle speeds after the HMI system activates. Analytical data show that many subjects highly appreciate the HMI system to continue safe driving. However, the data of pupil areas were significantly smaller with the HMI system. This implies that the concentration of drivers tends to decrease with the HMI system. The above results indicate that the HMI system is effective for drivers to be more aware of the risk of accidents when changing lanes and to make a safer decision. This remains to be an issue to determine whether drivers’ attention may tend to decrease with the HMI system.