Attitude Error Response of Structures to Actuator/Sensor Noise

One of the principal performance criteria in CSI optimization is the attitude error. This paper presents explicit closed-form formulas for the RMS attitude error response to sensor and actuator noise for co-located actuators/sensors as a function of both control gain parameters and structure parameters. The main point of departure is the use of continuum models. In particular the anisotropic Timoshenko model is used for lattice trusses typified by the NASA EPS Structure Model and the Evolutionary Model. One conclusion is that the maximum attainable improvement in the attitude error varying either structure parameters or control gains is 3 db at most for the axial and horizon modes, the bending being essentially insensitive. The results are similar whether the Bernoulli model or the anisotropic Timoshenko model is used.