Input Delay Compensation with Digital Redesigned A/D Conversion

Real-time random delay compensation with prediction-based digital redesign

“…Though differential equations or transfer functions are utilized in many papers [18], state-space model [15,16,34] is utilized in this article because it is convenient to realize state prediction as demonstrated in (7) [30]. The continuous-time state-feedback controller for the plant described by (1) is given as…”

“…This conventional open-loop local digital redesign method of making the conversion within the scope of the controller requires high sampling frequency; otherwise the digital controller may not be able to achieve a comparable performance due to the significant Analog-to-Digital (A/D) conversion error at low sampling frequency [30]. Leveraging on the recent hardware development that involves faster sampler, controller and switcher, the straightforward conversion method like bilinear transform is widely utilized in industry.…”

“…Leveraging on the recent hardware development that involves faster sampler, controller and switcher, the straightforward conversion method like bilinear transform is widely utilized in industry. Sometimes the analog control law is directly modulated through simple A/D conversion using Zero-Order-Hold (ZOH) [22,30].…”

“…Short controller period is not always beneficial because there are instances where longer controller period is better [30]. For example, in real-time NCS applications, slow data exchange rate reduces network traffic thereby improving network congestion and delay [9].…”

“…In addition, a small delay may be significant for fast controller rate, leading to complicated and time-consuming compensation calculations. However, the same time delay if described with longer period, may be only a fraction of the long controller period, then the compensation algorithm can be much simplified [30].…”