Development of a nonlinearly deterministic signal generator for real time chaos control testing

Chaotic dynamics have been successfully exploited in feedback control strategies. Recently, the authors have described the existence of unstable fixed points during ventricular fibrillation (VF), similar to those previously used in chaos control. Prior to embarking on control attempts of VF, a signal source was designed with known nonlinearly deterministic dynamics with well characterized stable and unstable manifolds as well as fixed point location. This ensured that the complex real-time data acquisition/analysis necessary to attempt such control was feasible for the interval durations typical of VF. A signal source was designed that can operate on any IBM compatible PC via the parallel port, and generates a waveform whose inter-event interval is nonlinearly deterministic with timing resolution of 0.1 /spl mu/sec with a range from 20 msec to 1.5 sec, independent of PC clock speed.