Vehicle control apparatus, vehicle control method, and vehicle control system

A vehicle control method comprising:

• receiving inputs of a target tire lateral force and a target tire longitudinal force that should be generated on a wheel of a vehicle, the target tire lateral force and the target tire longitudinal force being acquired based on a set route that the vehicle should run;
• outputting an instruction that achieves an optimal slip ratio corresponding to a minimum value of a sum of a first difference and a second difference to an actuator regarding braking/driving of the vehicle, the first difference being a difference between a tire lateral force and the target tire lateral force with respect to an arbitrary slip ratio in a correlative relationship between a slip ratio and the tire lateral force of a tire of the wheel, the second difference being a difference between a tire longitudinal force and the target tire longitudinal force with respect to the arbitrary slip ratio in a correlative relationship between the slip ratio and the tire longitudinal force;
• receiving an input of a maximum tire lateral force that can be generated on the wheel, the maximum tire lateral force being acquired based on the tire lateral force generated on the wheel and the slip ratio that are acquired based on detected vehicle behavior information;
• receiving an input of a maximum tire longitudinal force that can be generated on the wheel, the maximum tire longitudinal force being acquired based on the maximum tire lateral force;
• acquiring the correlative relationship between the slip ratio and the tire lateral force based on the maximum tire lateral force;
• and
• acquiring the correlative relationship between the slip ratio and the tire longitudinal force based on the maximum tire longitudinal force, wherein
• the first difference is a difference between the tire lateral force corresponding to each slip ratio calculated using a slip ratio-tire lateral force characteristic normalization map and the target tire lateral force, and the second difference is a difference between the tire longitudinal force corresponding to each slip ratio calculated using a slip ratio-tire longitudinal force characteristic normalization map and the target tire longitudinal force and
• control of the optimal slip ratio corresponds to the minimum value of a sum of the first difference and the second difference is performed in a state that the slip ratio falls within a range in which vehicle behavior is not disturbed.

A vehicle control system comprising:

• a vehicle behavior sensor configured to detect a behavior of a vehicle;
• and
• a vehicle motion control apparatus that is configured to:
• acquire a tire lateral force generated on a wheel of the vehicle based on vehicle behavior information detected by the vehicle behavior sensor;
• acquire a slip ratio of the wheel based on the vehicle behavior information;
• acquire a target tire lateral force that should be generated on the wheel based on a set route that the vehicle should run;
• acquire a target tire longitudinal force that should be generated on the wheel based on the set route;
• acquire a first difference, the first difference being a difference between the tire lateral force and the target tire lateral force with respect to an arbitrary slip ratio in a correlative relationship between the slip ratio and the tire lateral force of a tire of the wheel;
• acquire a second difference, the second difference being a difference between the tire longitudinal force and the target tire longitudinal force with respect to the arbitrary slip ratio in a correlative relationship between the slip ratio and the tire longitudinal force;
• acquire an optimal slip ratio corresponding to a minimum value of a sum of the first difference and the second difference;
• output an instruction that achieves the optimal slip ratio to an actuator regarding braking/driving of the vehicle;
• acquire a maximum tire lateral force generated on the wheel based on the tire lateral force acquired by the tire lateral force calculation portion and the acquired slip ratio;
• and
• acquire a maximum tire longitudinal force generated on the wheel based on the maximum tire lateral force, wherein
• the vehicle motion control apparatus is also configured to acquire the correlative relationship between the slip ratio and the tire lateral force based on the maximum tire lateral force, and acquire the correlative relationship between the slip ratio and the tire longitudinal force based on the maximum tire longitudinal force,
• the first difference is a difference between the tire lateral force corresponding to each slip ratio calculated using a slip ratio-tire lateral force characteristic normalization map and the target tire lateral force, and the second difference is a difference between the tire longitudinal force corresponding to each slip ratio calculated using a slip ratio-tire longitudinal force characteristic normalization map and the target tire longitudinal force and
• control of the optimal slip ratio corresponds to the minimum value of a sum of the first difference and the second difference is performed in a state that the slip ratio falls within a range in which vehicle behavior is not disturbed.