The delay approximation of discrete control in higher-order systems

✍ Scribed by M.H.N. Tabrizi; J.B. Edwards; R. Akras

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 620 KB
• Volume: 31
• Category: Article
• ISSN: 0895-7177
• DOI: 10.1016/s0895-7177(00)00112-6

✦ Synopsis

Physical machinery of high mathematical order operating in industry increasingly nowadays requires the replacement of early analog controllers by imbedded digital systems. Using a 7th-order longwall shearer as the motivating case-study, the paper examines the possibility of easing the digital control system design process by substituting a continuous transport-delay for the digital sample-hold operation. Based on first-and second-order models, this is shown to produce a design procedure that is pessimistic (i.e., safe) in the main and to a practically acceptable degree. Similar response speeds are generated by the discrete-and delay-models.

By simulation, the technique is shown to carry over well to the higher-order case study aforementioned. This provides confidence in the delay-for-sampler substitution, the advantages of which are that the need to generate multiple z-transform models for a range of sampling intervals and the difficulties of interpreting z-plane plots (compared to those of familiar Nyquist diagrams and root loci) are avoided.