A new relay feedback scheme for identification of non-minimum phase processes with time delay

Stabilizing region in dominant pole placement based discrete time PID control of delayed lead processes using random sampling

“…G 1 = (− 0.5 s + 1)e − 0.8 s /(s + 1) [41] Low-pass, stable 1 − 0.5 0.8 1 0.8 < 1 0.05 G 2 = (− s + 1)e − s /(2 s + 1) [42] Low-pass, stable 1 − 1 1 2 0.5 < 1 0.05 G 3 = (− s + 1)e − 0.2 s /(s + 1) [43] Low-pass, stable 1 [43] Low-pass, integrating 10 12 − 1 0 10 12 0 < 1 0.05 G 5 = (− s + 1)/(s + 1) [43] Low-pass, stable 1 − 1 0 1 0 < 1 0.05 G 6 = (0.3 s + 1)e − 0.2 s /(s − 1) [44] High-pass, unstable [44] High-pass, unstable [44] High-pass, unstable…”

Transfer function identification of a liquid flow-line pressure control system from simple relay auto-tuning

“…where, R is the setpoint given to the plant, ( R + h ′ 1 ) and ( R + h ′ 2 ) are the relay heights at ON and OFF conditions, respectively. Since the relay heights are chosen with respect to the setpoint, the generation of sustained oscillations from the considered dead-time processes is possible only when the condition given in Ghorai et al (2016) is satisfied. Thereafter, the measured quantities are obtained from a detailed analysis of sustained oscillatory output, as shown in Figure 2, and substituted in derived mathematical expressions for the evaluation of plant dynamic parameters.…”

“…Moreover, several frequency and time domain methods (Panda, 2006; Pekař, 2013) have been reported to estimate the unknown plant models in terms of TF form. The state-space approaches proposed by Atherton and Majhi (1998); Ghorai et al (2016); and Majhi (2007) yield more accurate process models as compared with the frequency domain method. This is because in frequency domain methods, relay gains are generally approximated by describing function (DF) approximation.…”