Suspension system

A suspension apparatus for supporting a payload, the suspension apparatus comprising:

• a base frame and a supported frame, the supported frame coupled to the base frame, the supported frame configured to be disposed vertically a neutral height above the base frame when a payload having a payload weight is disposed on the supported frame, the suspension apparatus configured to support relative displacement in a generally vertical direction between the supported frame and the base frame from a minimum height to a maximum height, the neutral height being between the minimum height and the maximum height, the supported frame being coupled to the base frame via:
• a guide system, the guide system comprising at least one guide configured to movably couple the base frame to the supported frame, the at least one guide being free to move as the supported frame and the base frame move closer to and farther away from each other, the guide system comprising only passive components;
• a coarse suspension device coupling the base frame to the supported frame, the coarse suspension device configured to oppose a relative displacement in the generally vertical direction between the base frame and the supported frame, the coarse suspension device being adjustable to support the payload at the neutral height, the coarse suspension device comprising only passive components;
• a mechanical assembly configured to convert the relative displacement in the generally vertical direction between the base frame and the supported frame into a generally horizontal displacement, the mechanical assembly comprising only passive components;
• and
• a fine suspension device operably coupled to the mechanical assembly to provide damping to the horizontal displacement from the mechanical assembly, the mechanical assembly and the fine suspension device coupling the base frame to the supported frame, the fine suspension device comprising:
• a passive portion comprising only passive components;
• and
• a semi-active portion comprising a sensor and a controller, the semi-active portion of the fine suspension device configured to further contribute to the damping provided by the passive portion alone, the semi-active portion configured to contribute to the damping only while the sensor determines that a sensed operating parameter falls within a predetermined range;
• wherein a force applied to one of the base frame and the supported frame in the generally vertical direction causes a generally opposite force to be applied to the other of the base frame and the supported frame, and
• wherein the damping provided by the fine suspension device and the mechanical assembly varies in a non-linear manner such that:
• the damping provided when the relative displacement in the generally vertical direction between the base frame and the supported frame by a given amount X below the neutral height is different than the damping provided when the relative displacement in the generally vertical direction between the base frame and the supported frame by a given amount X above the neutral height.