Abstract
This paper deals with the techniques of reproducing input waveforms of linear dynamic systems, which are the application of the theory of input observability by the author, and those of constructing quasi-invariant control systems using reproduced load or disturbance waveforms. Three methods of reproducing input waveforms are discussed, viz., analog and digital inverse circuit methods and a polynomial method. The last one does not include a difference operation and is applicable to systems whose input terminals are more than output terminals. We apply these three techniques to the measurement of the motor torque and the load torque waveforms of an induction motor system (0.2kw, 4 poles, 50hz).
This paper also shows the realizability of the quasi-invariant condition between a pair of input and output terminals with only one path. The approximation of the control circuit is enough for practical use, which is verified by the examination of a thyristor-leonard system and analog simulations.
