“…For its recognized advantages, there has been sustained interest in PID control. Some of the recent work on PID control has been focused on analytical studies, which have led to new findings, improved design and tuning rules on e.g., time delay systems, nonlinear systems, and extensions to multi-agent systems (Xu et al, 2013;Ma et al, 2020b). Specifically, steady-state tracking performance was examined in Åström and Hägglund (1995); Silva et al (2002), the delay robustness problems were studied in Silva et al (2002); Ma and Chen (2019); Chen et al (2019), and nonlinear regulation problems were considered in Zhao and Guo (2017).…”