A plurality of traveling wheels are supported via expandable/contractible tubular support members to a vehicle body frame. A hydraulic operation type vehicle height adjustment mechanism is provided for each one of the traveling wheels, the vehicle height adjustment mechanism being capable of switching a relative height of the traveling wheel relative to the vehicle body frame within a predetermined length range by expanding/contracting the support member by a hydraulic cylinder. There are provided a hydraulic control valve capable of controlling feeding state of work oil to each one of the plurality of hydraulic cylinders, a controlling section for controlling an operation of the hydraulic control valve to bring the vehicle body to a target state via vehicle height adjustment by the hydraulic cylinder in response to a change in the posture of the vehicle body and a plurality of accumulators connected oil chambers of the respective plurality of hydraulic cylinders.

In a vehicle height adjustment device, an operation amount of an actuator increases in accordance with supplied current, a detector detects a vehicle height, and a changer changes the vehicle height in accordance with the operation amount of the actuator. The changer shifts to a vehicle height increasing state or to a vehicle height decreasing state based on whether the operation amount is not higher than a predetermined amount. A controller controls the current supplied to the actuator to make the relative position have a target value. The controller determines a target current supplied to the actuator based on a control map that correlates a deviation between the target value of the relative position and a detection value to the target current.

A regenerative shock absorber that include a housing and a piston that moves at least partially through the housing when the shock is compressed or extended from a rest position. When the piston moves, hydraulic fluid is pressurized and drives a hydraulic motor. The hydraulic motor, in turn, drives an electric generator that produced electric energy. The electric energy may be provided to a vehicle, among other things. The regenerative shock absorber may also provide ride performance that comparable to or exceeds that of conventional shock absorbers.

A regenerative shock absorber that includes a housing and a piston that moves at least partially through the housing when the shock is compressed or extended from a rest position. When the piston moves, hydraulic fluid is pressurized and drives a hydraulic motor. The hydraulic motor, in turn, drives an electric generator that produced electric energy. The electric energy may be provided to a vehicle, among other things. The regenerative shock absorber may also provide ride performance that comparable to or exceeds that of conventional shock absorbers.

A regenerative shock absorber that include a housing and a piston that moves at least partially through the housing when the shock is compressed or extended from a rest position. When the piston moves, hydraulic fluid is pressurized and drives a hydraulic motor. The hydraulic motor, in turn, drives an electric generator that produced electric energy. The electric energy may be provided to a vehicle, among other things. The regenerative shock absorber may also provide ride performance that comparable to or exceeds that of conventional shock absorbers.

A regenerative shock absorber that include a housing and a piston that moves at least partially through the housing when the shock is compressed or extended from a rest position. When the piston moves, hydraulic fluid is pressurized and drives a hydraulic motor. The hydraulic motor, in turn, drives an electric generator that produced electric energy. The electric enemy may be provided to a vehicle, among other things. The regenerative shock absorber may also provide ride performance that comparable to or exceeds that of conventional shock absorbers.

In a vehicle height adjustment device, an operation amount of an actuator increases in accordance with supplied current, a detector detects a vehicle height, and a changer changes the vehicle height in accordance with the operation amount of the actuator. The changer shifts to a vehicle height increasing state or to a vehicle height decreasing state based on whether the operation amount is not higher than a predetermined amount. A controller controls the current supplied to the actuator to make the relative position have a target value. The controller determines a target current supplied to the actuator based on a control map that correlates a deviation between the target value of the relative position and a detection value to the target current.

Systems and methods for determining a status of a vehicle suspension system are disclosed. A vertical acceleration of the vehicle relative to a road surface is determined based on a position of a vehicle body. Based on a predetermined period of time, a peak value that corresponds to the vertical acceleration is calculated. The peak value is compared to a target peak value and, when the peak value meets a preset criteria, a notification of potential suspension degradation is issued.

Methods and apparatus are disclosed for adjusting the front to rear ratio of roll damping and/or roll stiffness in a vehicle based on vehicle yaw rate and/or the rate of change of steering wheel angle. Also disclosed are methods and apparatus for dynamically adjusting one or more suspension system control parameters based on one or more of steering wheel angle, rate of change of steering wheel angle and yaw rate.

A system for determining a displacement velocity signal for controlling an active wheel suspension of a land vehicle by open-loop and/or closed-loop control includes at least one Kalman filter, and at least one acceleration sensor arranged on a sprung mass of the land vehicle to sense a vertical acceleration of the sprung mass and to generate a corresponding acceleration signal supplied to the Kalman filter. The Kalman filter includes a mathematical motion model of the sprung mass, and input states of the Kalman filter include a vertical acceleration of the sprung mass, a vertical displacement velocity of the sprung mass, and a vertical displacement distance of the sprung mass. A displacement measurement signal having a value 0 is supplied continuously to the Kalman filter to determine the displacement velocity signal. Constant noise variance values of a measurement noise covariance matrix of the Kalman filter that are assigned to the displacement measurement signal are, in each case, set at one half of a maximum vertical displacement distance of the sprung mass.