ESTIMATION OF EXTERNAL FORCES FROM NOISY STATE MEASUREMENTS.

A technique is presented for the estimation of unknown forces that might be acting on a dynamic system. For input, the method may use input noisy measurements of any observable set of functions of the system states (including, trivally, the states themselves). The estimate is obtained from the solution of a two-point boundary-value problem and is in the form of an unmodeled disturbance-vs. -time trajectory. The method is derived, discussed, and illustrated by estimating several unknown forcing functions acting on a simple vibrating system.