Abstract: A vibration control system for a structure comprises an actuator connected in a truss structure as a structural member, for varying an axial stiffness in response to a control signal, at least one vibration sensor for producing a sensor signal representing a vibratory motion of the structure, and a controller for controlling vibrations of the structure by producing the control signal in accordance with the sensor signal. Preferably, the actuator comprises inner and outer tubes axially movable relative to each other, and a piezoelectric element which can change the axial stiffness of the actuator by allowing and preventing the relative movement between the inner and outer tubes.

Abstract: A collapsible truss structure in a basic form comprises eight joint connectors, twelve skeletal bars pivotally connected at their ends by the joint connectors, a diagonal bar or bars, and a slide hinge, and in its expanded or deployed state is in the shape of a rectangular parallelepiped formed by the twelve bars, the diagonal bar or bars being pivotally connected at its one end to one joint connector and extending diagonally within the deployed structure toward the most remote joint connector or connectors, near which the other end or ends of the diagonal bar or bars are pivotally connected to the slide hinge slidably fitted around one of the bars. The structure is collapsed by sliding the slide hinge away from said most remote joint connector. Lenghts of flexible bracing material can be stretched diagonally across bars of the structure to stably preserve the deployed state.

Abstract: A deployable truss composed of a plurality of three-dimensional truss units.

Abstract: A collapsible, or deployable, truss unit to be combined with a multiplicity of other similar units in an array for the construction of, for example, medium to large size frameworks in outer space. Each truss unit comprises two substantially rectangular arrangements of four rigid side members pivotally joined to one another, to be directed toward the opposite sides of the framework constructed, and four rigid cross members extending between the joints of the two rectangular arrangements of the side members. A flexible brace or braces are arranged diagonally of each rectangular arrangement of the side members. Two diagonally opposite ones of the four cross members have each a hinge assembly mounted thereto for longitudinal displacement. Each movable hinge assembly has two rigid diagonal members pivoted thereto each at one end, the other ends of the diagonal members being pivoted to two diagonally opposite ones of the four joints of one rectangular arrangement of side members.