GB1190983A - Planetarium System - Google Patents

Abstract

1,190,983. Computing for planetarium control. SPITZ LABORATORIES Inc. 12 May, 1967 [13 May, 1966 (2)], No. 22120/67. Heading G4G [Also in Division G2] A planetarium comprising a star field projector 4 having three axes of rotation, and planet projectors 5 each having a pair of reflecting mirrors 63, 65 mounted on a turntable rotatable about a vertical axis, the mirror 65 also being rotatable about a horizontal axis includes an electric analogue computer for controlling drive means associated with the projectors. The computer includes trains of electro-dynamic sine and cosine function generators and trains of hyperbolic function generators. In a sun-centred co-ordinate system the reference co-ordinates x p , y p , z p of a planet are computed by feeding into sine/cos. generators 80, 82, 84 inputs representative of the planet's distance from the sun and angles #, i and Q (Fig. 11, and Fig. 10, not shown). The reference co-ordinates of the Earth and an observer at a general point in the Solar System are computed by similar trains of sin/cos. generators (Figs. 13 and 14). A general planet position can then be computed by summing by means of amplifiers (98x<SP>1</SP>, 98y<SP>1</SP>, 98z<SP>1</SP>, Fig. 16, not shown) the outputs from the train of Fig. 11 and the negative outputs from the train of Fig. 14. The vectors fed to sin/cos. generators 110, 112, 114, 77, 70 together with inputs #I, 90-#II, #III representative of the angular position of the star field projector result in signals Ep, Ap which control motors for varying the position of the mirrors 63, 65. A pitch, yaw and roll computing means for the star field projector includes hyperbolic function generators 336, 346 (Fig. 33). The inputs to the computing means represent the rate of pitch, roll and yaw, which inputs act via the generators, amplifiers 338, 344, 348, 354 and motors 340, 350, 356 and tachometers 342, 352, 358 to produce outputs A, H, B which form inputs for further computing elements (224, 220) (Fig. 29, not shown).