Space shuttle main engine model identification

System identification techniques are used to represent the dynamic behavior of the SSME (space shuttle main engine). The comparison of the responses of a nonlinear simulation with the responses of an identified model indicates very good agreement. The identified model can be used for control design purposes. The identified model does not include valve linkage backlash and valve stiction nonlinearities. These nonlinearities should be added to the identified model, and the validity of the model should be checked by comparing it with the full nonlinear simulation. The identified model is valid for a limited response region at about the 100% power level operating condition.<>