Active vehicle seat suspension system

An active suspension system for isolating a seat of a vehicle from motion disturbances of the vehicle body, said active suspension system comprising:

• a support by which the seat is connected to the vehicle body and enabling movement of the seat along a given axis with respect to the vehicle body;
• a hydraulic actuator connected between the seat and the vehicle body to produce motion which counteracts influence of the motion disturbances of the vehicle body on the seat;
• an air bag connected between the seat and the vehicle body and having a spring preload which is variable to compensate for differing masses placed on the seat;
• a motion sensor which detects movement of the seat along the given axis and produces a motion signal in response to detected movement;
• a displacement sensor which detects an amount of displacement of the seat with respect to the vehicle body
• a force sensor which produces a force signal indicating a magnitude of force exerted on the actuator by the seat and an operator in the seat;
• and
• a controller connected to the force sensor, the motion sensor and the displacement sensor, wherein the controller responds to the motion signal by operating the actuator to nullify effects of the motion disturbances of the vehicle body from acting on the seat, and responds to the force sensor by varying the spring preload of the air bag to maintain the force exerted on the actuator to within a predefined range.

A seat assembly for a motor vehicle which nullifies motion disturbance of a vehicle body, said seat assembly comprising;

• a frame;
• a resilient seat cushion attached to the frame and forming a passive vibration isolator;
• a support by which the frame is connected to the vehicle body and enabling movement of the frame along a given axis with respect to the vehicle body;
• an active vibration isolator comprising an actuator and a spring connected between the frame and the vehicle body, wherein the actuator produces motion of the frame which counteracts influence of the motion disturbances of the vehicle body, and the spring connected has a preload which is variable to compensate for differing masses placed on the seat cushion;
• a motion sensor connected to the frame to detect movement along the given axis and produce a motion signal in response to detected movement;
• a force sensor which produces a force signal indicating a magnitude of force exerted on the actuator;
• and
• a controller which responds to the motion signal by operating the actuator to nullify effects of the motion disturbances of the vehicle body from acting on the seat, and which responds to the force signal by varying the preload of the spring to maintain the force within a predefined range.