Vehicle control system

1. A vehicle control system comprising a steer-by-wire system, wherein the steer-by-wire system comprising:

a steering device which is configured to turn wheels of a vehicle;

a reaction force device which is mechanically separated from the steering device and is configured to apply a steering reaction force to a steering wheel; and

a controller which is configured to control the steering reaction force by drive control of the reaction force device in response to an operation of the steering wheel;

wherein the controller is further configured to:

obtain a signal including a component due to a reaction force which acts on the wheels from a road surface;

extract a signal being greater than or equal to a predetermined frequency from the signal including the component due to the reaction force, the signal equal to or greater than the predetermined frequency includes a first signal which belongs to a first frequency band and a second signal which belongs to a second frequency band corresponding to a remaining frequency band rather than the first frequency band;

calculate a control amount of the reaction force device based on the extracted signal equal to or greater than the predetermined frequency; and

determine whether or not a predetermined condition is established, and when it is determined that the predetermined condition is established, weaken the first signal in the calculation processing of the control amount.

2. The vehicle control system according to claim 1 , wherein:

the predetermined condition is that the vehicle is in a braking state; and

the first frequency band is a frequency band of a low-frequency vibration which is generated during braking of the vehicle.

3. The vehicle control system according to claim 1 , wherein:

the predetermined condition is that the vehicle is traveling in a predetermined speed range; and

the first frequency band is a frequency band of a low-frequency vibration which is generated by flutter.

4. The vehicle control system according to claim 1 , wherein:

the vehicle is configured to run on a first or a second travel mode; and

the controller is further configured to calculate the control amount such that a vibration of the steering wheel is greater during a travel with the first travel mode than the travel with the second travel mode.

5. The vehicle control system according to claim 1 ,

wherein the signal equal to or greater than the predetermined frequency includes a signal

due to bumps and dips on roads.