Tetsuro Butsuen

Invariant Properties of Automotive Suspensions

Dynamic systems which are composed of interconnected sub-systems are subject to dynamic ‘constraint equations’ which are independent of the nature of the interconnections. A dynamic constraint equation is developed for a quarter car model of an automotive suspension. It is shown that only one of the three transfer functions (acceleration, suspension deflection and tyre deflection) can be independently specified and that the first two contain ‘invariant points’ at frequencies within the frequency range of interest. These constraint equations lead to conclusions with respect to trade-offs between the three transfer functions. Improvements in all three can be obtained near the unsprung natural frequency; however, severe trade-offs are shown to exist at all other frequencies.

Development of a rear-end collision avoidance system with automatic brake control

We have studied active safety technologies from the standpoint of “collision avoidance”. This paper describes a rear-end collision avoidance system with automatic brake control, which avoids a collision to the vehicle in front caused by inadvertent human errors using automatic emergency braking. The system is comprised of four key technological elements, headway distance measurement using scanning laser radar, path estimation algorithm with vehicle dynamics, collision prediction to the vehicle in front by a safe/danger decision algorithm, and longitudinal automatic brake control.

Application of sliding-mode theory to direct yaw-moment control

Abstract It has become popular to control vehicle manoeuvering with independent brakes for the avoidance of spin and drift-out. To ensure effective control, we applied sliding-mode theory, which enabled a robust control system against various driving conditions including changes in velocity, road friction and vehicle weight. By estimating the tyre status with a simple tyre model, the side slip angle of vehicle and road friction, we made it possible to easily install the system on vehicles. Our system is also equipped with parameter identification for correcting model errors. We confirmed the effectiveness of our system through full vehicle simulation and field tests.

Introduction of the Mazda Advanced Safety Vehicle

Mazda has developed Mazda ASV based on two technological themes; precautionary safety technologies which help reduce drivers error through an enhanced human interface between the vehicle and the driver, and accident avoidance technologies which function as a back-up in case of careless mistakes. Mazda focused on the facts that the mistakes of careless drivers have been the cause of the greater part of accidents and that about twenty percent of traffic deaths have happened while pedestrians cross streets. To help solve these problems, Mazda actively takes part in the Study Group for Promotion of ASV (Advanced Safety Vehicle) headed by the Japanese Ministry of Transport, and researches and develops advanced safety technologies. This paper introduces the concept of accident prevention based on the analysis of traffic accidents and the accident avoidance technologies we developed and installed on Mazda ASV.