Minimizing the truncation error in assumed modes models of structures

The assumed modes approach is a widely used technique in modeling of distri buted systems. Such models often consist of a large number of modes. For co ntroller design purposes these models are simplified by truncating the mode s that lie out of the bandwidth of interest. Truncation can alter zeros of the system. This paper presents a method of minimizing the truncation error by adding a second order term to the truncated model. This extra term is d etermined such that the in-bandwidth error is minimized in an optimal H-2 s ense. The technique is extended to multivariable systems. [S0739-3717(00)02 003-1].