The United States of America as Represented by the United States

United States of America as Represented by the Administrator of Nasa

Jer-Nan Juang

Meng-Sang Chew

Li-Farn Yang

A suspension device is provided for simulating the free-free boundary conditions of space for a low frequency structure. A support cable is connected at one end to the test structure and is vertically guided by a guiding ring. The other end of the cable is connected to a cam having an outer circumference which supports the cable. A drive axle passes through the cam center of rotation and is rotatably journalled in a suitable manner to a rigid structure. Two torsion springs are provided about the drive axle. One end of each spring is connected to a respective face of the cam and the other end is connected to the fixed support. The cam is shaped and the torsion springs selected such that Wr.sub.(t) =T.sub.s(t), wherein W is the weight of the test structure; r.sub.(t) is the instantaneous moment arm defined as the perpendicular distance from the rotational center of the cam to the cable at time t, and T.sub.s(t) is the total spring torque exerted by the two springs on the cam at time t. The test structure is accordingly vertically suspended by the cable and the instantaneous moment arm compensates for any increased spring torque arising from a vertical displacement of the test structure to simulate space conditions.

Suspension device for low-frequency structures

A rolling joint is provided for obtaining slewing maneuvers for various apparatuses including space structures, space vehicles, robotic manipulators and simulators. Two noncircular cylinders, namely a drive and a driven cylinder, are provided in driving contact with one another. This contact is maintained by two pairs of generally S-shaped bands, each pair forming a generally 8-shaped coupling tightly about the circumferential periphery of the noncircular drive and driven cylinders. A stationarily fixed arm extends between and is rotatably journalled with a drive axle and a spindle axle respectively extending through selected rotational points of the drive cylinder and of the driven cylinder. The noncircular cylinders are profiled to obtain the desired varying gear ratio.

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Poquoson, VA, United States of America

Jer-Nan Juang