Womack, B. F. | Engineering Papers

NASA NTRS1975

Time domain desensitized specific optimal system design

A digital computer algorithm for desensitized specific optimal system design for general time-invariant nonlinear systems is presented. The algorithm utilizes a technique of partitioning and uncoupling of the original specific closed-loop system state and sensitivity equations into linear, nonlinear, and control subsystems. Results of the application of the algorithm in the design of a Saturn V Launch Vehicle analog attitude control system and an LST image motion compensation digital controller are given.

Henson, T. F.↗

NASA NTRS1974

Digital simulation by partitioning and uncoupling the system model

The present work reviews state variable simulation and then proposes a technique for simulation of nonlinear time varying systems by partitioning the system state variable model and uncoupling the resulting subsystem models so that the linear time-invariant ones can be simulated by state variable solution. Computational requirements and computer time are shown to be reduced. The method does, however, introduce an integration error due to the treatment of the intercoupling terms between the subsystems as inputs which are assumed constant over a computation interval. A fictitious sampler is thereby introduced, which is then derived in the form of a state variable error model. The application of this method in a simulation error analysis for a Saturn V attitude control system model and the simulation of a detailed nonlinear, single-axis model of the LST fine pointing control system is described.

Henson, T. F.↗