Robust fault reconstruction in uncertain linear systems using multiple sliding mode observers in cascade

Copyright © 2010 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In observer-based fault reconstruction, one of the necessary conditions is that the first Markov parameter from the fault to the output must be full rank. This paper seeks to relax that requirement by using multiple sliding mode observers in cascade. Signals from an observer are used as the output of a fictitious system whose input is the fault. Another observer is then designed and implemented for the fictitious system. This process is repeated until the first Markov parameter of the fictitious system with respect to the fault is full rank. The result is that robust fault reconstruction can be carried out for a wider class of systems compared to other works that also seek to relax the requirement of a full rank first Markov parameter. In addition, this paper has also investigated and presented the necessary and sufficient conditions as easily testable conditions, and also the precise number of observers required. A simulation example verifies the effectiveness of the scheme. © 2006 IEEE

Sliding mode estimation schemes for incipient sensor faults

This is the author's preprint vetrsion of an articles submitted to Automatica. The definitive published version is available via doi:10.1016/j.automatica.2009.02.031This paper proposes a new method for the analysis and design of sliding mode observers for sensor fault reconstruction. The proposed scheme addresses one of the restrictions inherent in other sliding mode estimation approaches for sensor faults in the literature (which effectively require the open-loop system to be stable). For open-loop unstable systems, examples can be found, for certain combinations of sensor faults, for which existing sliding mode and unknown input linear observer schemes cannot be employed, to reconstruct faults. The method proposed in this paper overcomes these limitations. Simulation results demonstrate the effectiveness of the design framework proposed in the paper. © 2009 Elsevier Ltd. All rights reserved

New results in disturbance decoupled fault reconstruction in linear uncertain systems using two sliding mode observers in cascade

This paper presents a disturbance decoupled fault reconstruction (DDFR) scheme using two sliding mode observers in cascade. Measurable signals from the first observer are found to be the output of a fictitious system that is driven by the fault and disturbances. Then the signals are fed into a second observer which will reconstruct the fault. Sufficient conditions which guarantee DDFR are investigated and presented in terms of the original system matrices, and they are found to be less conservative than if only one single observer is used; therefore DDFR can be achieved for a wider class of systems using two sliding mode observers. A simulation example validates the claims made in this paper

Design of urea granulator with energy optimization

Urea granules are one of the popular fertilizers among synthetic fertilizer industry. Its main function is to provide nitrogen which enhances leaf growth on plant. Urea granules are produced from the process of granulation. Granulation process is divided to wet and dry granulation. Generally, there are two type of dry granulator which is slugger and roller compactor. Roller compactor or also known as roll press is using two counter rotating rolls to compact raw material such as powder to become ribbons or granules. If ribbons instead of granules arc produced from compaction, milling will be used to produce granules. It is difficult obtain a numerical result of the process due to the variety of parameters. Therefore, this work will only consider the parameters which are related to feeder system and roller. The parameters include the feeding rate of feeder, roller force, roller pressure, and roller gap size. While powder flow to roller from feeder, overfeeding may occurs. Overfeeding is harmful because it will cause motor failure. To overcome this problem, the function of roller needs to be improved. The roller will be modified and hence, a new design will be produced

DESIGN OF A UREA GRANULATOR WITH ENERGY OPTIMIZATION

Urea granules are one of the popular fertilizers among synthetic fertilizer industry. Its main function is to provide nitrogen which enhances leaf growth on plant. Urea granules are produced from the process of granulation. Granulation process is divided to wet and dry granulation. Generally, there are two type of dry granulator which is slugger and roller compactor. Roller compactor or also known as roll press is using two counter rotating rolls to compact raw material such as powder to become ribbons or granules. If ribbons instead of granules are produced from compaction, milling will be used to produce granules. It is difficult obtain a numerical result of the process due to the variety of parameters. Therefore, this work will only consider the parameters which are related to feeder system and roller. The parameters include the feeding rate of feeder, roller force, roller pressure, and roller gap size. While powder flow to roller from feeder, overfeeding may occurs. Overfeeding is harmful because it will cause motor failure. To overcome this problem, the function of roller needs to be improved. The roller will be modified and hence, a new design will be produced