Fuzzy based variable step approaching digital control for plants with time delay

Guomin Li, K. M. Tsang, Siu Lau Ho

Research output: Journal article publicationJournal articleAcademic researchpeer-review

12 Citations (Scopus)


A simple digital controller named Variable Step Approaching Digital Controller (VSADC) based on fuzzy concept is proposed for plants with time delay. The proposed controller is basically a modified Takagi-Sugeno Type Fuzzy Controller and can be represented by a compact analytical equation with only several adjustable parameters. The tuning rule and self tuning scheme in constant value control are developed. Detailed simulation investigation is carried out. Verification experiment using Process Trainer PT326 heating system as testbed is conducted. The proposed controller is compared with PID controller tuned by well-known Ziegler and Nicliols's ultimate cycle method. Both simulation and experimental results show that the proposed VSADC is effective in suppressing overshoot and in attenuating decaying oscillation cycles. It is also superior to PID controller in the control of plants with dominant time delay.
Original languageEnglish
Pages (from-to)167-176
Number of pages10
JournalISA Transactions
Issue number3
Publication statusPublished - 1 Dec 1998


  • Control algorithm
  • Digital control
  • Fuzzy control
  • Process control
  • Time delay

ASJC Scopus subject areas

  • Instrumentation
  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Applied Mathematics


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