Vehicle suspension system

A suspension system for a vehicle comprising a vehicle body supported on wheels, the system comprising:

• a pressure fluid circuit having a source of pressure fluid, double-acting hydraulic actuators each having a piston movable in a cylinder and each being operative between the vehicle body and a respective one of said wheels,
• electro-hydraulic servo valves, each valve connecting a respective one of said hydraulic actuators into said pressure fluid circuit,
• transducer means associated with each hydraulic actuator and having electrical outputs dependent on actuator loading and actuator piston displacement,
• circuit means responsive to said transducer outputs to generate signals representative of forces corresponding to at least one of the heave pitch roll and warp modes of movement of said vehicle body and to treat said signals so as to obtain control signals for said servo valves whereby said hydraulic actuators are actuated to maintain said vehicle body in a predetermined attitude.

A road vehicle comprising:

• a vehicle body,
• road wheels supporting said vehicle body,
• double-acting hydraulic actuators, each hydraulic actuator being operative between a respective one of said road wheels and said vehicle body to adjust the spacing therebetween,
• a source of pressure fluid,
• an electro-hydraulic servo valve associated with each hydraulic actuator for controlling flow of the pressure fluid between said source thereof and said associated hydraulic actuator,
• fluid pressure accumulator means connected between each of said hydraulic actuators and said fluid pressure source,
• a first and second transducer means associated with each of said hydraulic actuators for providing output signals dependent respectively on the forces acting on the hydraulic actuator piston and on the displacement thereof within the actuator, and
• control means receiving said transducer means output signals and providing output control signals controlling said electro-hydraulic servo valves to thereby maintain said vehicle body in a predetermined attitude, said control means comprising:
• a signal conditioning unit have input means and output means said input means being connected to said transducer means to receive said output signals thereof,
• a measurement transformation unit having input means connected to said signal conditioning unit output means, to receive said output signals after conditioning by said unit and output means,
• said measurement transformation unit providing at said output means thereof signals representing displacement in at least two of the heave pitch roll and warp modes of movement of said vehicle body,
• computer means having input means and output means, said input means thereof being connected to said measurement transformation unit output means, and said computer means being adapted to provide displacement and displacement demand signals at said output means thereof,
• a comparator having input means and output means, said input means thereof receiving said displacement and displacement demand signals from said computer means output means and said comparator being adapted to provide error signals at said output means thereof, and
• a servo drive means having input means and output means, said input means being connected to comparator output means and said servo drive output means being connected to said servo control valves.