Vibration isolation system

Abstract

A horizontal-motion vibration isolation system for supporting an object in an equilibrium position relative to a base while suppressing the transmission of horizontal vibratory motion between the object and the base includes a plurality of columns, each column having a rigid member with a first end and a second end. A tilt mechanism is operatively connected to each first end of the rigid members and the object. Likewise, a tilt mechanism is operatively connected to each second end of the rigid members and the base. Each tilt mechanism exhibits a tilt rotational stiffness and the horizontal translation of the object relative to the base causes tilt rotation of the columns. The tilt rotational stiffness of the tilt mechanisms is approximately proportional to the compression load transmitted to the columns by the weight of the object, so that the horizontal natural frequency of the system is nearly insensitive to the payload weight. The tilt mechanism can be made from a plurality of tension members which are relatively stiff in axial tension and relatively flexible in bending. For example, the tension members can be made from thin wires, strings, filaments, cables, thin and narrow sheet metal strips or other sheet material. Alternatively, each tilt mechanism can be made with an end fitting that presses into a relatively deformable pad. The end fitting has a contoured shape so that as the weight load on the column increases, the contact area between the fitting and the deformation of the pad increases. Other tilt mechanisms include the use of a non-linear spring or a plurality of non-linear springs.