Health Indices Construction for Stochastically Deteriorating Feedback Control Systems

Degradation Modeling and RUL Estimation of Feedback Control Systems using Stochastic Diffusion Process

“…Our research problem is started from building a system-level degradation index of (1) for the monitoring of its degrading process. As explained in (Gong et al, 2022), the system matrices are unknown so that they propose to estimate the transfer function at each inspection date of the original FCS (1) via a couple of observable input and output, then extracts alternative system-level indices that contain the information of D(t, x(t)). However, directly observing the transfer function of original FCS cannot reveal more about the degradation occurring in the system plant, as the original welldesigned controller offsets part of the inner damage on system for the reason of achieving the control goal.…”

“…To validate the developed RUL prognosis method in Eq. ( 18), we consider a deteriorating FCS which is a inertial platform thoroughly introduced in (Gong et al, 2022) whose structures is…”

“…RUL is the residual lifetime of the degraded FCS from its current deteriorating state until its failure. Approaches for predicting the pRUL of FCS generally falls into two categories, as illustrated in our previous work (Gong et al, 2022). One is to model the component degradation of the system by stochastic processes so that the probability density function (PDF) of the first hitting time (FHT) are then calculated for RUL prognosis via the selected model, where the FHT is the first time when the degradation index exceeding the failure threshold, Do and Söffker (2021).…”

“…It can thereafter be applied to obtain a prognostic system RUL. In (Gong et al, 2022), we apply merely the input and output information of the deteriorating FCS to estimate their transfer functions, then extract the pole position changes and maximum gains as two system-level degradation indices. The strong effects from the controller make the output of the FCS track its input but at the same time offsets part of the degradation and makes it difficult to be inspected at the early degrading stage, but increase dramatically when FCS approaches the failure.…”

“…It is well known that calculating the RUL distribution based on stochastic degradation models can save a significant amount of time and expense compared to only using Monte Carlo simulation. Therefore, our work is carried out on the basis of establishing a system-level degradation index using a similar approach of (Gong et al, 2022) which are then modeled using stochastic processes for the purpose of obtaining analytical PDF of RUL by means of probability calculation. For reducing controller effects on the health index, we set up an extra controller for obtaining the degradation information from the FCS.…”