Brief paper: Inversion of sampled-data system approximates the continuous-time counterpart in a noncausal framework

  • Authors:

  • Takuya Sogo

  • Affiliations:

  • Department of Mechanical Engineering, Chubu University, Aichi 487-8501, Japan

  • Venue:
  • Automatica (Journal of IFAC)
  • Year:
  • 2008

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Abstract

Although correspondence between the poles of a continuous-time and sampled-data system with a piecewise constant input is simple and desirable from the stability viewpoint, the relationship between zeros is intricate. Inversion of a sampled-data system is mostly unstable irrespective of the stability of the continuous-time counterpart. This makes it difficult to apply inversion-based control techniques such as perfect tracking, transient response shaping or iterative learning control to sampled-data systems. Although recently developed noncausal inversion techniques help us to circumvent unboundedness of the inversion caused by unstable zeros, whether the inversion of sampled-data systems approximates the continuous-time counterpart or not as the sample period is shortened is still to be determined. This article gives a positive conclusion to this problem.