Roll vibration damping control system for vehicle, target roll moment computing method therefor, and non-transitory computer-readable storage medium

A roll vibration damping control system for a vehicle, the roll vibration damping control system comprising:

• a roll angular acceleration sensor configured to detect a roll angular acceleration of a vehicle body;
• an actuator configured to generate a roll moment to be applied to the vehicle body, wherein the actuator includes in-wheel motors respectively assembled with wheels of the vehicle, and the actuator generates the roll moment by using front and rear wheel forces of the wheels that are converted to up and down forces by suspensions corresponding to the wheels;
• and
• an electronic control unit configured to:
• compute a sum of a product of a roll moment of inertia of the vehicle and the roll angular acceleration detected by the roll angular acceleration sensor, a product of a roll damping coefficient of the vehicle and a first-order integral of the roll angular acceleration, and a product of an equivalent roll stiffness of the vehicle and a second-order integral of the roll angular acceleration, as a controlled roll moment to be applied to the vehicle body,
• compute a roll moment around a center of gravity of a sprung mass as a correction roll moment, the roll moment being generated by lateral force on wheels due to roll motion,
• compute a target roll moment based on a value obtained by correcting the controlled roll moment with the correction roll moment,
• compute target braking and driving forces of the wheels to be controlled by the in-wheel motors for applying the target roll moment to the vehicle body, and
• control the in-wheel motors based on the computed target braking and driving forces to control the front and rear wheel forces such that the roll moment that the in-wheel motors generate becomes the target roll moment, wherein
• the roll moment, Mxδ, is expressed by Mxδ=hsfFyfδ+hsrFyrδ, where hsf is a roll arm length at a position of the front wheels that is a difference between a height of the roll center and a height of the center of gravity at the position of the front wheels, hsr is a roll arm length at a position of the rear wheels that is a difference between a height of the roll center and the height of the center of gravity at the position of the rear wheels, Fyfδ are the tire lateral forces at the front wheels, and Fyrδ are the tire lateral force at the rear wheels,
• the tire lateral forces, Fyfδ, at the front wheels are expressed by
• F
• yf
• ⁢
• δ
• =
• C
• f
• ⁢
• l
• r
• l
• ⁢
• mg
• (
• δ
• f
• -
• β
• f
• )
• ,
• where Cf is a normalized equivalent cornering power of the front wheels, lr is a distance in a vehicle front and rear direction between the center of gravity of the vehicle and a rear wheel axle, l is a distance in the vehicle front and rear direction between a front wheel axle and the rear wheel axle, m is mass of the sprung mass, g is gravitational acceleration, δr is a wheel steering angle of the front wheels, and βf is a slip angle of the front wheels, and
• the tire lateral forces, Fyrδ, at the rear wheels are expressed by
• F
• yr
• ⁢
• δ
• =
• C
• r
• ⁢
• l
• f
• l
• ⁢
• mg
• (
• δ
• r
• -
• β
• r
• )
• ,
• where Cr is a normalized equivalent cornering power of the rear wheels, if is a distance in the vehicle front and rear direction between the center of gravity of the vehicle and the front wheel axle, m is mass of the sprung mass, g is the gravitational acceleration, δr is a wheel steering angle of the rear wheels, and βr is a slip angle of the rear wheels.