Development of an advanced strapdown inertial system

Attention is given to the development of a laboratory model of an airborne computer associated with a strapdown gyro unit manufactured by an U.S. aerospace company. The considered system should satisfy the requirements for a small satellite launcher. The inertial unit includes two dry tuned-rotor gyros and two-scale digitizers. The computing system includes a 8087 numeric coprocessor and an 8086 16-bit processor. The 8087 implements with high speed and precision floating-point operations including trigonometric functions. The algorithm for the computer is discussed, taking into account the use of the quaternion method for obtaining attitude information. In an evaluation of the merits of the selected computing system it is pointed out that the availability of low cost high performance numeric processors gives the sounding rocket community the possibility of using a powerful airborne computer of standard design, with enough capability to implement a strapdown inertial reference system.