Simulation Associates, Inc.

This note summarizes the simulation of the boost phase of a spin-stabilized missile on the ARTS system. The model includes six degrees of freedom, and requires 20 integrations, 4 trigonometric functions, 14 arbitrary functions of 1 variable, 2 transport delays, and considerable algebraic computation. This classic benchmark has been run on many computer systems, from PC's to supercomputers.

Before the advent of the ARTS system with the STARLIGHT [1] Accelerator, the only commercially-available digital computer which could run this simulation in real time was the Cray Y-MP, which cost several million dollars. In contrast, a basic ARTS system with the STARLIGHT Accelerator can run the simulation six to ten times faster than the Cray, and costs less than 150 thousand dollars.

The wide range of frequencies and time constants in this system is typical of applications that require very high speed computation. The angular rates Ps, Qs, Rs are of the order of 2 - 5 Hertz, so that the missile itself is not a particularly high-frequency system. But the control system contains a filter with a time constant of 670 µsec (corresponding frequency about 240 Hertz), and generates thrust pulses with a duration of a few milliseconds, so that the controller is quite "stiff".

The ARTS system is programmed in the Advanced Real-Time Simulation language (ARTS), an ACSL [2] -like language which conforms to the industry-standard CSSL, as defined by the Society for Computer Simulation [3] . It allows straightforward programming in equation form, without the need for any detailed knowledge of integration methods. The language also provides for user-defined macros: if a system contains similar subsystems, the common part can be packaged as a macro, which is written and tested only once and called repeatedly. This feature eliminates repetitious coding, insures that identical subsystems are represented identically, and encourages modular program development.

FOOTNOTES

[1] STARLIGHT is a trademark of EAI Simulation Associates, Inc.

[2] ACSL is a product of MGA Software.

[3] Strauss, J.C.; Augustin, D.C.; Fineberg, M.S.; Johnson, B.B.; Linebarger, R.N.; and Sanson, F.J. "The SCI Continuous System Simulation Language (CSSL)." Simulation, December 1967.