Abstract: An active suspension system of a vehicle has a feed back control system for controlling four suspensions for the four wheels to maintain a reference vehicle height responsive to detected vertical relative displacements between the wheels and the vehicle body at said suspensions, and a feed forward control system for controlling the suspension to maintain an intended rolling of the vehicle responsive to detected lateral acceleration. There is further provided a circuit for changing the reference vehicle height which is responsive to the absolute value of the detected lateral acceleration, and operates to reduce the reference vehicle height with increase of the absolute value so that the vehicle body is lowered while the rolling is maintained whereby a better driver's sensation during a vehicle turn is obtained and the capability of turning of the vehicle is improved.

Abstract: In a motor vehicle having a vehicle height adjusting device, wherein the height of each suspension is controlled so as to attain a set reference vehicle height, reaction forces of respective suspensions are detected and a difference between the detected reaction forces is calculated according to a formula, while the vehicle is stationary or is being driven straight. When the difference exceeds a predetermined value, it is determined that there are imbalances of the road surface contact loads of the wheels. Upon the determination of imbalances, the reference vehicle height is increased for some suspensions and decreased for other suspensions to eliminate the imbalances. The determination of imbalances is made when a value given by a formula including the integrated values for the suspensions exceeds a predetermined value, and then reference vehicle height is increased and decreased for the suspensions to eliminate the imbalances.

Abstract: In a system for controlling active suspensions of a motor vehicle, having fluid suspensions for the respective wheels, a lateral acceleration sensor, control valves for the respective suspensions, and a controller for adjusting the control valves to charge and discharge a fluid into and out of the fluid suspensions so as to control the vehicle attitude, a shut-off valve is provided between each control valve and each fluid suspension. The shut-off valve is normally open to enable the control of the vehicle attitude in an active state. When the detected lateral acceleration of the vehicle during a turn exceeds a set reference lateral acceleration, an active-passive changeover circuit delivers a shut-off signal to each shut-off valve thereby to close the shut-off valve, whereby all the fluid suspensions are sealed so that the suspension system becomes a passive state.

Abstract: An apparatus for adjusting a body height of a vehicle by supplying or discharging air into or from an air suspension system includes a controller for controlling a vertical vehicle body height to a predetermined set value responsive to a signal according to an adjustment amount of the vehicle body height obtained by subtracting an objective reference vehicle body height signal from a relative displacement signal. The apparatus further includes vehicle body height change control means connected to the controller for variably controlling a vehicle body height adjustment completion time and a vehicle body height adjusting speed responsive to the vehicle speed.

Abstract: In a system for controlling active suspensions of a motor vehicle, having fluid suspensions for the respective wheels, a longitudinal acceleration sensor, a lateral acceleration sensor, control valves for the respective suspensions, and a controller for producing a control quantity to adjust the control valves to charge and discharge fluid into and out of the fluid suspensions so as to control the vehicle attitude, the reaction force of each suspension is detected and a mean value of the suspension reaction force is calculated to determine the loading condition of the vehicle while the vehicle is driven straight ahead at a constant speed. The control quantity is corrected by a correcting circuit so as to match the loading condition of the vehicle whereby the vehicle attitude is precisely controlled so as to match the vehicle weight even in such a transient state as acceleration, deceleration and turning. The internal pressure of each suspension may be detected as the reaction force.

Abstract: In a system for controlling active suspensions of a motor vehicle, having fluid suspensions for the respective wheels, a longitudinal acceleration sensor, control valves for the respective suspensions, and a controller for adjusting the control valves to charge and discharge a fluid into and out of the fluid suspensions so as to control the vehicle attitude, a hysteresis circuit is provided to receive a longitudinal acceleration signal from the acceleration sensor, for hysteresis processing of the signal, whereby microvibration components included in the acceleration signal is removed. The width of hysteresis is increased as the vehicle speed increases because the amplitude of microvibration becomes larger as the vehicle speed increases. For more stable vehicle attitude control, a dead-zone circuit is provided to cut fluctuations of the hysteresis-processed signal within a specific width in the vicinity of zero.

Abstract: An active suspension system of an automotive vehicle having four air suspension units for four wheels has a first sensor for detecting vertical acceleration of the mass above each suspension unit spring, a second sensor for detecting the vertical relative displacement of the masses above and below each unit spring, a controller for operating in response to the output signals from the two sensors and a relative displacement velocity signal obtained by differentiation of the signal from the second sensor to generate an instruction air flow quantity signal, and a control valve operating in response to this flow quantity signal from each controller to control the charging or discharging of air into or from each unit. An auxiliary damper is provided in each unit to damp vibrations of relatively high frequencies.

Abstract: A control unit for an active suspension system of a vehicle. The control unit includes a longitudinal g sensor for sensing longitudinal g of the vehicle body to generate a longitudinal g signal; and a control instruction quantity calculating circuit for calculating a control instruction quantity of a fluid to be charged into or discharged from each of suspension units in response to the longitudinal g signal to generate and transmit a control instruction quantity signal representing the control instruction quantity to a fluid charge and discharge control circuit for controlling to charge into or discharge from each suspension unit, whereby the vehicle body is controlled in response to the longitudinal g so that the vehicle body is effectively held in an ordinary position.

Abstract: An apparatus for controlling an active suspension system for an automotive vehicle comprises hydraulic suspensions, control valves for independently controlling each of the suspensions and a controller for issuing a signal for controlling of opening/closing of the respective control valves. The apparatus includes a longitudinal g sensor for detecting a longitudinal acceleration of a vehicle body and a lateral g sensor for detecting a lateral acceleration of the vehicle. To calculate a control quantity relative to feeding of hydraulic fluid in and discharging of the hydraulic fluid from the respective suspensions required for suppressing pitching and rolling of the vehicle body, the apparatus further includes a control logic which in the controller. A control quantity derived from the circuits is added to another control quantity derived from a vertical g acceleration sensor and a vertical relative displacement sensor, and the resultant control quantity is delivered to the control valve for each suspension.

Abstract: To carry out a method of controlling a plurality of active suspensions for an automotive vehicle, a normal/reverse rolling selection switch and a plurality of correction logics are provided in a control system including a longitudinal acceleration sensor and a lateral acceleration sensor. The correction logics correct a quantity of rolling moment, a variation of suspension reactive force, a control quantity of fluid and variation of a reference vehicle height. A signal from the lateral acceleration sensor and a signal from the normal/reverse rolling selection switch are inputted into a reference vehicle height correcting circuit to control a reference vehicle height corresponding to each active suspension.

Abstract: Vehicle height control for a motor vehicle which has height adjusting means for each of wheel suspensions and which is stationary on a distorted road surface. Height control is carried out for either one of the front wheel suspension pair and the rear wheel suspension pair to attain a reference vehicle height for both the left and right wheels of the one pair whereby the vehicle part having said one pair assumes an attitude parallel to the inclination of the road surface in a direction transverse to the vehicle part. For the other pair of the wheel suspensions, height control is carried out such that the opposite part of the vehicle with the other pair of the wheel suspension will assume an attitude substantially equivalent to the attitude of the first mentioned vehicle part, whereby a good balance is obtained between the contact loads of the wheels.

Abstract: An apparatus for adjusting height of a vehicle includes an incremental-type rotary encoder operated as a sensor for sensing the height of the vehicle. The incremental-type rotary encoder comprises a rotary disc having two sets of slits positioned at circumferential portions having different radii each other and different phase of 90.degree. in a rotating direction of the rotary disc. The incremental-type rotary encoder is further provided with a slit having a semi-circular shape disposed along a circumferential periphery thereof. A neutral position of an operation range of the rotary disc is determined as a boundary of the location of the semi-circular slit. The semi-circular slit is detected to discriminate whether height of the vehicle is above or below the neutral position of the rotary disc. A height adjusting mechanism is displaced in a vertical direction according to data from a detector. The apparatus controls the rotating direction and the amount of the rotation of the rotary disc.

Abstract: An active suspension of a motor vehicle is controlled by a system and a method which comprise combining a controller and an actual flow quantity estimation circuit for estimating by logic operation the flow quantity of the fluid actually flowing through each control valve of the suspension with respect to a total desired flow quantity, and calculating the difference between the actual flow quantity value thus estimated and the desired flow quantity, thereby correcting the desired flow quantity. A command signals is generated and transmitted in accordance with the desired flow quantity thus corrected for operating the control valve to undergo opening/closing operation.

Abstract: An active fluid suspension system has a controller for controlling the delivery and withdrawal of air to and from individual suspension units at vehicle wheels in response to the sensor output signals representing a prescribed set of vehicle behaviors. The controller includes insensitivity zone filters each for filtering out those portions of one sensor output signal of which amplitudes are within an insensitivity zone, thereby avoiding unnecessary fluid flow into and out of the suspension units. The insensitivity zone is defined as a range of amplitudes between given positive and negative values. The filters widen the insensitivity zones with an increase in vehicle speed for optimum suspension control in all vehicle speed ranges.