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A driving simulator capable of duplicating the critical sensations incurred during a spin, or when a driver is engaged in drift cornering, was constructed by Mitsubishi Heavy Industries, Ltd., and Hiromichi Nozaki of Kogakuin University. Specifically, the simulator allows independent movement along three degrees of freedom and is capable of exhibiting extreme yaw and lateral acceleration behaviors. Utilizing this simulator, the control characteristics of drift cornering have become better understood. For example, after a J-turn behavior experiment involving yaw angle velocity at the moment when the drivers attention transitions to resuming straight ahead driving, it is now understood that there are major changes in driver behavior in circumstances when simulator motions are turned off, when only lateral acceleration motion is applied, when only yaw motion is applied, and when combined motions (yaw + lateral acceleration) are applied.

In this research, we examine the three controls inside-outside wheel braking force and driving force, camber angle, and the derivative steering assistance to determine how angle differences affect cornering performance and controllability. This is accomplished by comparing body slip angle area differences in a closed loop examination of the grip to drift area using a driving simulator. The results show that inside-outside wheel braking force and driving force control in the area just before critical cornering occurs has a significant effect on vehicle stability. We also clarified that controlling the camber angle enhances grip-cornering force, and confirmed that the sideslip limit could be improved in the vicinity of the critical cornering area. Additionally, when the counter steer response was improved by the use of derivative steering assistance control in the drift area exceeding the critical cornering limit, corrective steering became easier.

A new steering method to improve control during cornering is examined using a driving simulator, and the following findings were obtained. During cornering, there is a danger that it is not possible to finish curving is course out by the only differentiation steering. However, the driver can easily maintain a drift in the drift area when assisted by differentiation steering, and the behavior of the return to a straight course becomes stable. Therefore, since a remarkable effect was expected by controlling the steering method corresponding to the running condition, an examination experiment was performed. The shapes of the waves of initial steering at start up differ according to the running condition, and as a result, initial steering of the steering wheel is a two-step motion in J-turn running. In contrast, smooth steering proceeds without steps in the lane change running.

As for this research, the driver’s risk at the time of cornering was evaluated. As a result, the amount of perspiration became a big difference though the change in the amount of the vehicle state of non-drive skill person and the drive skill person did not have a remarkable difference at the time of the drift cornering. That is, the amount of perspiration when the steer is controlled in case of the drive skill person is small. Therefore, it has been understood that it is a steer control of the risk which is not too large.

In general, the longitudinal position of the center of gravity of a vehicle has a great influence on lateral acceleration in critical cornering. Most rear-wheel-drive vehicles (front engine, rear-wheel drive) have a tendency to be over-steered because the driving power acts on the rear wheels, and so the forward weight distribution is large. As such, the vehicle has an under-steer tendency in this respect and an overall balance is achieved. On the other hand, because formula cars are very light compared to general vehicles, the used area of the vertical wheel load-maximum cornering force characteristic, differs greatly from general vehicles. That is, although general vehicles use a nonlinear area for the vertical wheel load-maximum cornering force characteristic of the tire, a comparatively light formula car uses an almost linear area in the vertical wheel load-maximum cornering force characteristic of the tire.

In this research, driver risk (subjective feeling of danger) during pylon slalom and drift turning was evaluated by measuring the amount of driver perspiration. The result (the product of the amount of maximum perspiration and the perspiration amount area at the unit running time) is believed to correspond to a subjective rating of the feeling of danger. Moreover, a peculiar phenomenon was observed during drift cornering in which a large degree of fear was experienced if there was a possibility that the vehicle might spin, thus considerably increasing the amount of perspiration. Here, perspiration amount area shows the total amount of perspiration, additional to baseline levels, over a given time frame. And, unit running time shows the same as saying ‘averaged over time’

A drift-turn experiment to assess the influence of differences in steering wheel gear ratios was undertaken using a driving simulator. It is relatively easy to maintain control of a commercial vehicle if the tire is in contact with the road surface and the steering wheel gear ratio is 15.0:1 to 18.0:1. Conversely, in the event of a change in traction such as the rear wheel meeting a drift area, a steering wheel gear ratio of 7.5:1 to 9.0:1 is required to maintain control of the vehicle, even when the vehicle became unstable. Moreover, the stability of the vehicle deteriorates in drift running if the steering gear ratio is reduced too much. That is, the steering gear ratio in which the drift angle is maintained most easily is in the range 7.5∼9.0. And, a drift performance evaluation index D n=x was determined and was found to agree with the subjective ratings. Thus, evaluating drift control for drift cornering using the drift performance evaluation index was assumed to be effective.

It has been reported that steering systems with derivative terms have a heightened lateral acceleration and yaw rate response in the normal driving range. However, in ranges where the lateral acceleration is high, the cornering force of the front wheels decreases and hence becomes less effective. Therefore, we applied traction control for the inner and outer wheels based on the steering angle velocity to improve the steering effectiveness at high lateral accelerations. An experiment using a driving simulator showed that the vehicle's yaw rate response improved for a double lane change to avoid a hazard; this improves hazard avoidance performance. Regarding improved vehicle control in the cornering margins, traction control for the inner and outer wheels is being developed further, and much research and development has been reported. However, in the total skid margin, where few margin remains in the forward and reverse drive forces on the tires, spinout is unavoidable.