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We investigated and analyzed the average vehicle-driver's braking behavior in panic situations by conducting vehicle tests that duplicated real world conditions that would require emergency braking performance. From our investigation, we have noticed that when panic braking is recognized, supplying additional braking power is effective for active safety. The Brake Assist System, which supplies full constant braking force when panic braking is recognized, is effective for drivers who cannot apply enough braking effort. However, in some case, such a system makes more experienced drivers uncomfortable because the deceleration caused by this full constant braking force might be different from their intentions. Considering these issues, we have developed the Brake Assist System that increases its controllability while reducing its discomfort. The TOYOTA RAUM has been available with the Brake Assist System since May 1997.

Because of recent advances in steering control technology, steer-by-wire systems have continued to become more realistic. The principal issue for these steer-by-wire systems is considered to be promoting reliability through the construction of a design concept that can be utilized appropriately by drivers. This paper first describes the flow between the concept and system structure, and proposes a steer-by-wire system with a mechanical backup mechanism as one possibility. This paper also describes an investigation into its potential advantages using an experimental vehicle installed with the proposed system structure. The potential advantages of steer-by-wire are improved vehicle driving performance, vehicle maneuverability, and the feasibility of innovative packaging and design. In order to make improved maneuverability and design innovations compatible, it is critical to achieve steering characteristics that require little maneuvering angle.

In vehicle control systems such as ABS (anti-lock braking system) or active suspension control, sensors for detecting longitudinal and/or lateral acceleration of vehicles (acceleration of up to ± 9.8 m/s2, with frequency range of DC to 20 Hz) is necessary. The principle of acceleration detection for this sensor is as follows. A permanent magnet levitates steadily in magnetic fluid by the action of the magnetic field generated by the magnet itself. The magnet moves by the application of acceleration on the mass of the magnet. This change of position of the magnet is detected by the Hall element, and thus acceleration is measured as an electrical signal. This sensor consists of only magnetic fluid, a permanent magnet, housing, a pair of Hall elements and an electronic circuit.

At an early stage of developments, brake performances are usually obtained from a simulation using a brake dynamometer. However the brake parts on the dynamometer will not operate at exactly the same temperature as that fitted to a road vehicle, because the cooling factors are different. Also the load on the brakes on the dynamometer is different from the actual load. The effects of temperature and load on brake performances were investigated and it was found that over a considerably wide range the frictional coefficients of brake materials are only minimally affected by the cooling factors and load. Brake performances calculated from the experimental data obtained from dynamometer tests using different line pressures and velocities as parameters show good coincidence with the actual road test results, so the simulations can be used to effectively estimate brake performance at planning stage of the vehicle.

The wheel torque measuring system (abbr. WTMS) has been developed for evaluating the torque applied to each wheel of automotive vehicles under actual running conditions. WTMS is a novel type system in which the torque signal is transmitted by a high-performance and compact photo-telemetric coupling system. Within the torque measurement range of ±2.94 kN·m, the resolution of torque output is ±1 N·m so that torque can be measured with an extremely high degree of accuracy. Therefore, measurements can be taken from the high torque applied in the case of a quick accelerating test or a sudden braking test to the measurement of a low amount of torque such as running resistance of a vehicle.