| 摘要 |
<p>PROBLEM TO BE SOLVED: To further surely suppress instability of a vehicle behavior on a slippery road surface by calculating a value corresponding to horizontal direction grip force that a rear wheel generates at present and relatively reducing steering auxiliary force as the value approaches a capacity limit of a tire. SOLUTION: An auxiliary steering torque command value Ta obtained from speed V and manual steering torque Ts is added to a steering resistance torque command value Tc obtained from steering resistance torque Tcf and steering resistance correction torque Tcr and a motor 4 is controlled. Because a rear wheel becomes a spin tendency when horizontal force utilization factorξr of the rear wheel exceeds about 1, steering resistance force is generated in a power steering device as the horizontal force utilization factorξr approaches about 1 and steering auxiliary force is relatively reduced. Thus, an oversteering tendency is eliminated and stability of a vehicle on a slippery road can be improved because a driver recognizes overtuning of a steering wheel and returns a front wheel steering angle.</p> |
