A super-twisting observer for atomic-force reconstruction in a probe microscope

Kaiqiang Zhang, Toshiaki Hatano, Thang Tien Nguyen, Christopher Edwards, Guido Herrmann, Stuart Burgess, Massimo Antognozzi, Said Khan, Robert Harniman, Mervyn Miles

Research output: Contribution to journalArticle (Academic Journal)


This paper presents a new methodology employing a super-twisting sliding mode observer to reconstruct un-measureable atomic-forces at nano-Newton precision in a Vertically Oriented Probe Microscope (VOPM). The VOPM senses the deflection of a vertically oriented cantilever, caused by shear-force interaction with a confined water layer above the sample-substrate. The paper describes the development of a model and the subsequent experimental process for computing its parameters. This forms the basis for the design of a super-twisting observer to estimate the unknown shear-forces. The reconstructed force can be decomposed into elastic and viscous components, which are important in biological research
Original languageEnglish
Article number104191
Number of pages12
JournalControl Engineering Practice
Early online date15 Nov 2019
Publication statusPublished - 1 Jan 2020


  • Probe Microscope
  • Shear Force
  • Elastic and Dissipative Force
  • Sliding Mode Control
  • Super-Twisting Observer

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