Development of Distance Control Assist System with Accelerator Force Control and Braking Force Control

This paper describes the development of a distance control assist system with an active accelerator pedal and a deceleration control. This system was developed for the purpose of assisting a driver to maintain a safe following distance behind a lead vehicle. In this system, if the host vehicle driver is depressing the accelerator pedal, the system helps the driver let up on the accelerator by generating force to push the pedal upward. Depending on the proximity to the vehicle ahead, the system changes the sensitivity of the engine to the driver's accelerator inputs, making it easier for the driver to discern the pedal reactive force. In addition, the system may apply the brakes smoothly to decelerate the host vehicle, depending on the following distance, relative velocity and other factors at the time the driver releases the accelerator pedal. In a situation where the host vehicle approaches closer to the vehicle ahead and the driver is depressing the accelerator pedal, the system sounds a buzzer and flashes a message on the instrument panel urging the driver to be careful. The authors report on field tests that were conducted to evaluate the effectiveness of this system. Results demonstrated that frequency and magnitude of deceleration by the driver were decreased, and, from the characteristics of TTC (Time to Collision) distribution, frequency of closing situations were decreased. The authors hypothesize that this result that might contribute to the reduction of necessary brake action by the driver. The AWWL (Adapted Weighted Workload) score on the NASA-TLX (Task Load Index) and the salivary amylase activity score were also analyzed and the results showed a decrease in the driver’s workload by using the system.