Abstract: A characteristic is set to a first transmission force characteristic. A sensitivity is set to a first sensitivity. The maximum value of the square of a product of a value representing the first transmission force characteristic and a value representing the first sensitivity in a predetermined frequency range preset so as to include a frequency at which the value representing the first transmission force characteristic takes a peak value is set to an evaluation indication value. A complex spring constant in the vehicle longitudinal direction of the rear wheel suspension is set so that the evaluation indication value takes the minimum value out of values in a variable range of the evaluation indication value.

Abstract: A characteristic relating to transmission of a longitudinal force input to a front wheel from the front wheel to a vehicle body is set to a first transmission force characteristic. A sensitivity of the vehicle to the longitudinal force transmitted from the front wheel to the vehicle body is set to first sensitivity. The maximum value of the square of a product of a value representing the first transmission force characteristic and a value representing the first sensitivity in a predetermined frequency range preset so as to include a frequency at which the value representing the first transmission force characteristic takes a peak value is set to an evaluation indication value. A complex spring constant in the vehicle longitudinal direction of the rear wheel suspension is set so that the evaluation indication value takes the minimum value out of values in a variable range of the evaluation indication value.

Abstract: A vehicle suspension device includes a suspension device main body configured to support a wheel of a vehicle to a vehicle body of the vehicle; an upper intervening member configured to be intervened between a vertically upper portion of the suspension device main body and the vehicle body so that a front-back stiffness of the vehicle is relatively decreased at a time of smooth-braking of the vehicle at which an absolute value of a braking force of the vehicle is relatively small, compared to at a time of non-braking of the vehicle; and a lower intervening member configured to be intervened between a vertically lower portion of the suspension device main body and the vehicle body so that the front-back stiffness of the vehicle is relatively increased at the time of smooth-braking of the vehicle, compared to at the time of non-braking of the vehicle.

Abstract: The height of a vehicle can be estimated inexpensively by: detecting a wheel speed, which is a speed of each wheel; performing frequency analysis of the detected wheel speed of a pair of left and right wheels and calculating respective wheel speed characteristics of the left and right wheels at a gain-specific frequency; calculating a left-right wheel speed gain difference on the basis of the calculated wheel speed characteristics of the left and right wheels; and estimating the vehicle height on the basis of a corresponding relationship between a wheel height of the wheel with respect to a vehicle body and a value (wheel speed/road surface input gain) that is based on wheel speed and a road surface input that is inputted from the road surface to the wheels, and on the basis of the left-right wheel speed gain difference.

Abstract: A vehicle suspension device includes a suspension device main body configured to support a wheel of a vehicle to a vehicle body of the vehicle; a varying device configured to cause an upper connecting portion stiffness and a lower connecting portion stiffness to be variable, the upper connecting portion stiffness being a stiffness between a vertically upper portion of the suspension device main body and the vehicle body, and the lower connecting portion stiffness being a stiffness between a vertically lower portion of the suspension device main body and the vehicle body; and a control device configured to control the varying device at a time of braking of the vehicle to perform control which causes the upper connecting portion stiffness to be relatively decreased and causes the lower connecting portion stiffness to be relatively increased, compared to at a time of non-braking of the vehicle.

Abstract: The height of a vehicle can be estimated inexpensively by: detecting a wheel speed, which is a speed of each wheel; performing frequency analysis of the detected wheel speed of a pair of left and right wheels and calculating respective wheel speed characteristics of the left and right wheels at a gain-specific frequency; calculating a left-right wheel speed gain difference on the basis of the calculated wheel speed characteristics of the left and right wheels; and estimating the vehicle height on the basis of a corresponding relationship between a wheel height of the wheel with respect to a vehicle body and a value (wheel speed/road surface input gain) that is based on wheel speed and a road surface input that is inputted from the road surface to the wheels, and on the basis of the left-right wheel speed gain difference.

Abstract: A vehicle suspension device includes a suspension device main body configured to support a wheel of a vehicle to a vehicle body of the vehicle; an upper intervening member configured to be intervened between a vertically upper portion of the suspension device main body and the vehicle body so that a front-back stiffness of the vehicle is relatively decreased at a time of smooth-braking of the vehicle at which an absolute value of a braking force of the vehicle is relatively small, compared to at a time of non-braking of the vehicle; and a lower intervening member configured to be intervened between a vertically lower portion of the suspension device main body and the vehicle body so that the front-back stiffness of the vehicle is relatively increased at the time of smooth-braking of the vehicle, compared to at the time of non-braking of the vehicle.

Abstract: A vehicle suspension device includes a suspension device main body configured to support a wheel of a vehicle to a vehicle body of the vehicle; a varying device configured to cause an upper connecting portion stiffness and a lower connecting portion stiffness to be variable, the upper connecting portion stiffness being a stiffness between a vertically upper portion of the suspension device main body and the vehicle body, and the lower connecting portion stiffness being a stiffness between a vertically lower portion of the suspension device main body and the vehicle body; and a control device configured to control the varying device at a time of braking of the vehicle to perform control which causes the upper connecting portion stiffness to be relatively decreased and causes the lower connecting portion stiffness to be relatively increased, compared to at a time of non-braking of the vehicle.

Abstract: A vehicle control device acquires a roll changing amount generated in a vehicle, acquires a pitch changing amount generated in the vehicle, synthesizes the roll changing amount and the pitch changing amount to acquire a synthesized value, and controls a front/rear wheel damping force distribution based on the synthesized value. The vehicle control device includes a roll damping force varying unit that detects a vehicle speed, detects a road surface in-phase/reverse-phase ratio, and controls a roll damping force by a variable roll damping control amount, where the front/rear wheel damping force distribution is determined from a front/rear wheel damping force distribution map based on the vehicle speed, the road surface in-phase/reverse-phase ratio, and the roll damping control amount.