Performance of ensemble time-varying system identification methods: Analog simulations and biological applications

The performance of two ensemble time-varying system identification techniques were evaluated using an analog electronic circuit whose time-varying behavior was known analytically. Comparison of theoretical impulse responses with those obtained from system identification showed that either the "shifted-input" method or an SVD-based method can accurately track very rapid variations in system dynamics on a sample-by-sample basis. The application of one of these techniques to characterize muscle stiffness during an isometric twitch is also described.