Dear Malyala Venkata Satya Sai Chandra,

The two methods observer and analytical redundancy based fault-tolerant control are almost algebraically equivalent, there have been demonstrations in this direction, however we can note differences between them such as the distinction of faults and failures, the clear isolation and finally the detection is faster thanks to the algorithms developed based on analytical redundancy for attenuation type defects.

For more deatails and information about this subject i suggest you to see links and attached files on topic.

https://www.hindawi.com/journals/mpe/2015/429361/

https://www.sciencedirect.com/topics/engineering/fault-tolerant-control

https://www.sciencedirect.com/science/article/pii/S2405896317305207

https://www.hindawi.com/journals/mpe/2015/429361/

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Best regards

Thank you very much for your answer Mohamed-Mourad Lafifi

The observer based methods are not at all popular methods for sensor fault tolerant control. As answer above, you can used robust resilient control method without observer for fault-tolerant control with its tremendous significance. Here are some examples:

Article Frequency domain analysis of resilient consensus in multi-ag...

Article Robust fault-tolerant self-recovering control of nonlinear u...