Sliding mode control for active vibration isolation of a long range scanning tunneling microscope

An active vibration isolation (AVI) system has been designed and implemented for the Molecular Measuring Machine (M3) at the National Institute of Standards and Technology (NIST). NIST is investigating active vibration isolation as an approach to improving the M3 image resolution and measurement speed. This article presents the full dynamic model of the AVI system with the Mallock suspension used for the M3 system suspension. A decoupling process is employed to decompose the complicate dynamics into separate axis. This article then applied a sliding mode controller (SMC) to overcome the system nonlinearities. Experimental results show that the controller is effective, achieving a vibration attenuation of 10 dB at some frequencies, depending on the axis.