A relative performance monitor for process controllers

Abstract

A monitor is developed to automatically detect poor control performance. It provides a measure (relative performance index}RPI) of a control-loop performance relative to a reference model of acceptable control. The reference model simulates the controlled variable output of a user-defined, acceptably tuned control loop. The inputs to the reference model are the setpoints (same as the true plant) and the disturbances (estimated from the measurements). The monitor uses routine plant operation data only. Pending ability to obtain temporally accurate process models, and the validity of process measurements, simulations and experiments show that the monitor can detect the poor control performance caused by improper controller parameter values or changes in plant characteristics, and can distinguish it from poor performance caused by external disturbances.

Control loop performance assessment: a classification of methods

“…In [42] Li et al develop a monitor to automatically detect poor control performance. The monitor provides a measure (Relative Performance Index -RPI) of a control loop performance relative to a reference model of acceptable control.…”

Assessment of high-integrity embedded automotive control systems using hardware in the loop simulation

“…Franklin et al 1994;Torngren 1998) and performance monitoring (e.g. Li et al 2003), and more generally quantifications of jitter, delays and latency plus measures of processor and memory utilisation in the system have all been suggested as useful (and sometimes necessary) benchmarks to evaluate (Bate 1998;Pont 2001;Storey 1996;Torngren 1998). All of these techniques are particularly well suited to HIL simulation, as they can be directly integrated into the hardware and software infrastructure.…”

“…A real-time performance monitor is introduced into the simulator environment that compares the behaviour of the real, hardware/software based system with the desired system behaviour (see Figure 9). The performance monitor that is to be employed is an adapted version of the design presented by Li et al (Li et al 2003). The monitor is used to detect persistent deviations from the specification that are indicative of system failures (e.g.…”

Assessment of performance and dependability in embedded control systems: Methodology and case study

“…From recent survey material, an analysis of the existing methodologies reveals that from the point of view of HIL simulation, where dynamic models of the process under control are readily available, a model-based approach would seem to be the most suitable. The methodology presented in this paper is an adapted version of the relative performance monitor presented by Li et al (2003).…”

“…These reference model outputs are then passed, along with the actual controlled outputs, to the metric generator for further comparison and processing, to generate the performance assessment. Many different methodologies may be used to generate these metrics; the approach taken by Li et al (2003) to generate the performance metric is to use the ratio of reference and actual weighted moving average of squared errors, as shown in (5): ) (…”