Analog sensitivity design of Saturn V launch vehicle

This paper describes a useful method for limiting the sensitivity of high-order systems to unknown changes in specific parameters. A brief review of the development of sensitivity coefficients and the governing sensitivity equation is given. The desensitization problem is then formulated as an optimal control problem with a specified feedback structure and performance indices defined for both the state and sensitivity vectors. A method of iteratively finding the optimal feedback gains by simultaneous solution of the state and sensitivity equations via analog computer is described and an algorithm is given. This method of analog sensitivity design is then applied to a seventh-order model of a Saturn V booster with the frequency of the first bending mode serving as the unknown parameter. Analog sensitivity design is shown to produce a control system with sensitivity to the varying parameter greatly reduced over that of the corresponding system designed without using sensitivity considerations.