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We analyzed the forward collision mitigation effect of the driving load reduction system using market data. The analysis was conducted by comparing the frequency of forward collisions for each distance when Adaptive Cruise Control was used or not used on the same road type. The frequency while using the system on the highway was 1 / 2.1 of not using. We consider that most of this result is the effect of reducing by using the driving load reduction system. However, more factors that affect the frequency can be considered, so further investigation is required. [ABSTRACT FROM AUTHOR]

Merging in a highway is one of the most difficult driving tasks. In lane changing and merging, drivers consider about safety and longitudinal ride comfort. In addition, drivers must finish merging in the merging zone. The jerk, which is the rate of change of acceleration, is important factor for longitudinal ride comfort. Suppressing the jerk improves ride comfort. On other hand, it causes the possibility of merging failure because of the increase of travel distance. In order to improve the longitudinal ride comfort, this paper presents the merging support system suppressing the jerk under the constraint of the merging zone. It consists of the merging decision maker, the merging planner and the vehicle controller. The merging decision maker compares the selectable merging positions and selects one with smallest acceleration considering the constraint of the merging zone. The merging planner generates the velocity plan and the lateral path plan to reach to the selected merging position. These plans suppressing the longitudinal and lateral jerk by applying the 3-sgate moving average filter. The vehicle controller follows the velocity plan and the lateral path plan accurately. This controller considers the vehicle delay by applying the model predictive control. The performance of the proposed system is tested by simulations. These simulations show that the proposed merging support system contributes safe and comfortable merging.

The number of vehicles equipped with adaptive cruise control (ACC) is increasing, reflecting a trend toward autonomous vehicle development. It is expected that ACC systems will improve traffic in terms of string stability (i.e., attenuation of spacing errors along a vehicle string). For a group of vehicles without string stability, fluctuation in inter-vehicle distance is amplified as it propagates rearward, which may cause traffic congestion. It will take a few decades to replace all human-driven vehicles with autonomous vehicles. Communication technology such as fifth-generation mobile communication systems enables vehicle-to-vehicle communication with a sufficiently small delay. This paper proposes a method for avoiding traffic congestion based on distributed autonomous control. In the proposed method, autonomously controlled vehicles that satisfy string stability are distributed with adequate spacing to constrain the fluctuation of the distance between human-driven and standard ACC vehicles. The conditions for the string stability of distributed autonomously controlled vehicles are derived. The validity of the proposed method is demonstrated using numerical simulations.

This paper presents the merging support system considering the constraint of the merging zone. Merging in a highway is one of the most difficult driving tasks. In lane changing and merging, drivers consider about safety and longitudinal ride comfort. In addition, drivers must finish merging in the merging zone. To achieve these objectives, we propose the merging support system. It consists of the merging decision maker, the merging planner, the longitudinal controller and the lateral controller. The merging decision maker compares the selectable merging positions and selects one with smallest acceleration. The merging planner generates the velocity plan and the lateral path plan to reach to the selected merging position. The longitudinal and lateral controllers follow these plans by the feedback controller and the feedforward controller. The performance of the proposed system is tested by simulations. In these simulations, the merging decision maker and the merging planner calculates the velocity plan and the lateral path plan to finish merging in the merging zone with the smallest acceleration, and the longitudinal and lateral controllers follows these plans accurately. These results show that the proposed merging support system contributes safe and comfortable merging. In addition, we demonstrate that the length of the merging zone affects the merging decision.

In adaptive cruise control (ACC), it is important to improve ride comfort and safety. Distance and acceleration have a significant influence on ride comfort and safety, and there is a trade-off relation between distance and acceleration. Therefore, driving characteristics of ACC should be changed according to various driving scenes. This paper proposes control strategy and design method considering a trade-off between distance and acceleration. In proposed control strategy, driving behavior of ACC is expressed by combination of transient behavior and steady behavior. An example of transient behavior is approaching to a slow vehicle, and an example of steady behavior is following to a breaking vehicle. The proposed control is based on 2-degree of freedom control, it consists of feedforward and feedback controllers. A feedforward controller is designed for transient behavior, and a feedback controller is designed for steady behavior independently. In proposed control design method, driving characteristics for transient behavior is defined by 2-stage moving average filter. Time constants of the filter are theoretically linked to the required distance response and acceleration response. Simulation results show that driving scenes of ACC is expressed by combination of transient behavior and steady behavior. In addition, 2-stage moving average filter defines the response of ACC directly, it contributes to consider a trade-off between distance and acceleration.

In general braking control methods of adaptive cruise control, control input is decided based on relative distance and velocity between the preceding vehicle and the ego vehicle at the moment. Such an approach is affected by acceleration/deceleration of the preceding vehicle directly. Therefore, there is a possibility that the response of the ego vehicle becomes oscillatory, and ride comfort gets worse. In this paper, a braking control method based on driver's characteristics is proposed in order to perform adaptive cruise control considering not only safety but also ride comfort. We construct a system with following ways. First, driver's characteristics are extracted from driving data of an expert driver. The following results were obtained: the human braking behavior is divide into three parts, and it does not depend on vehicle velocity of the ego vehicle and the preceding vehicle. Second, the generation method of reference values for braking control is proposed with extracted characteristics. We consider regeneration of reference values when the preceding vehicle accelerates or decelerates during braking of the ego vehicle. Finally, a longitudinal control method is proposed, and the stability of the system is proved. From results of a simulation and an actual vehicle experiment, it was found that our method can reproduce an expert driver's braking behavior.

In aging society, welfare personal vehicles have been widely used to improve the quality of life of elderly and handicapped persons. However, it is difficult for the users to steer the vehicle in narrow buildings. Accordingly, platoon driving of welfare personal vehicles has attracted attention as one of the effective leading methods. The platoon driving system consists of the longitudinal control and the lateral control. The longitudinal control is based on Adaptive Cruise Control. If the vehicle parameters are adjusted for each user’s driving ability, the longitudinal control will be string unstable in the worst case. As for the lateral control, the following vehicle tracks the preceding vehicle according to the target point following algorithm. The following vehicle may collide with a wall due to the large tracking error at a sharp corner in buildings. In this paper, the robust and precise platoon driving system is proposed to realize the safe platoon driving. Firstly, the longitudinal controller stably keeps the inter-vehicle distance regardless of the short time-headway. Secondary, the lateral controller precisely tracks the wheel track of preceding vehicle by using way-points. Thirdly, the robust platoon control for the different vehicle dynamics is designed by Model Error Compensator. Finally, the effectiveness of our proposed system is evaluated by the driving experiments.