Experiments of inverted pendulum as a vertical reference of a telescope

We propose an attitude control system for a telescope utilizing an inverted pendulum. We put a tube with a sharp bottom end on an XY linear translation stage, and surround the top by a ring with 4 pressure gauges inside. We made experiments with a device composed of an inverted pendulum which can move only in one direction. The device is composed of a tube with a conical bottom, a linear translation stage, a monitoring tilt meter, supporting springs, a laser displacement sensor and a frame. The laser displacement sensor which is substitution of pressure gauges measured extension/contraction of the springs between the tube and the frame. We have succeeded in keeping it vertical with the accuracy of better than 1 arc sec.