Fig. 3a. SIMFAC simulator: Shuttle orbiter operator complex. SIMULATION MODEL VERIFICATION During the RMS program, both real and nonreal time orbiter/RMS models had been devised by Spar, NASA and other contractors and each model had to be properly verified. Each organization is responsible for different elements of system verification with NASA holding prime responsibility. To check the RMS simulation models, a common data base has been generated for all models and a set of common validation runs performed on each. During the orbiter’s second, third and fourth flights, the previously simulated manoeuvres were performed and the actual flight data compared to the simulations. As variations are found, the simulation data base is changed accordingly and identical runs repeated for various payload masses. To give a general idea of the type of test performed, three examples are presented below. To confirm the response of the arm when the orbiter’s primary reaction control system is fired, the arm is variously positioned with and without payloads. Upon firing the orbiter jets, the arm’s modal frequencies, the modal amplitude, deflection amplitude, accelerations and loads are measured. To confirm predicted manual mode operation, the arm is commanded to move and stopped by using brakes, removal of command and safing. The data produced gives loads and servodynamic responses. To confirm automatic modes, the arm is commanded to a series of positions and thus the closed loop position response, control accuracy and drift dead-band can be
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