Vehicular kinetic characteristics such as running, turning, or stopping are changed depending on operating points of devices (e.g., engine, steering, suspension, brake, or other vehicular mechanisms), further, depending on slopes of roads. Therefore, a driver conducts predictive operations after understanding the vehicular kinetic characteristics, or conducts modifying operations after understanding vehicular actions. Namely, the driver needs to respond to variations of the vehicular characteristics.
Specific Examples are as Follows.
1) Characteristics variations due to devices
Switching transmission shift positions changes a driving characteristic to an accelerator operation. For instance, an acceleration/operating gain varies because of a gear ratio, or a response varies because of operating points of a torque converter or an engine.
Further, a response is changed by variations in engine operating points, e.g., engine revolution numbers or loads. For instance, in a gasoline-port injection engine, a response is changed by a response of an air system, switching due to a control, or a control of a valve for an inlet/outlet air.
Furthermore, in general, a vehicle is designed to slightly under-steer as a turning curvature increases (or a lateral acceleration increases). For instance, a vehicle is designed by considering a weight distribution, a suspension geometric structure, a suspension kinematics, or a tire characteristic. The vehicle that is thus designed tends to go short of additional steering when the vehicle enters a sharper curve during turning.
2) Characteristics variations due to road shapes
A road slope changes a vertical load balance in the front and rear wheels, which thereby further changes a steering characteristic. For instance, in an ascending slope, the load in the front wheel decreases, so the vehicle tends to under-steer. In contrast, in a descending slope, the load in the front wheel increases, so the vehicle tends to over-steer. Further, a vehicular kinetic characteristic is changed depending on a road-surface frictional coefficient μ. Therefore, the driver needs to understand a road surface condition.
Driver's recognition or sense of acceleration or turning during vehicle's traveling is differentiated even when the same acceleration or the same turning is conducted in individual cases as follows: when a curve or a slope is present ahead of a vehicle, when a preceding vehicle is present ahead of a vehicle, or when a road becomes narrower ahead of a vehicle. Further, conditions such as brightness or weather surrounding the relevant vehicle affect the driver's recognition. The recognition or the sense of the driver is changed depending on a distance of a driver's gaze.
In detail, as a vehicle position slants, a sense of acceleration or a sense of turning may become strong. For instance, when the front end of a vehicle goes up (nose up) because of driving, the sense of accelerating may increase. When the front end of a vehicle goes down (nose diving) because of braking, a sense of decelerating may increase. Further, when a vehicle rolls during turning, a sense of turning may increase.
Thus, a driver needs to properly conduct an operation since relationships between various parameters are changed by influences of the vehicular characteristics or road environments. The various parameters include actual accelerating, decelerating, or turning action; vehicular positions at the relevant actions; and driver's operations for individual parts of the vehicle that cause the foregoing