Fault-tolerant control for batch processes - Overview and outlook

Most processes can be divided into two classes: batch processes and continuous processes. In general, batch processes, which run intermittently, are best suited to low-volume and high-value products. Due to the high value of products, much more requirements are proposed for the control performance of batch processes. Hence, the plants become more and more complicated to achieve the high requirements. Consequently, the process complication exposes the possibility of system faults. Therefore, there is a trade-off between high performance and reliability. Fault-tolerant control (FTC) should be a good choice to handle this trade-off. Unfortunately, the reported work on FTC for batch processes is scarce. Trying our best, only four papers in the subject area were found by the authors. Therefore, both great challenges and opportunities exist in this field. Compared to continuous processes, batch processes have mainly three features: repetitive nature, finite duration, and nonlinear property. Generally, faults can be divided into three classes based on their location; FTC methods include two classes according to whether fault detection and diagnosis (FDD) is used; in addition, the proposed scheme could be linear or nonlinear. By means of these criteria, the existing papers are categorized. Thanks to these categorizations, some promising directions will be presented in this paper.