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 (M-3) at the National Institute of Standards and Technology (NIST). NIST is investigating active vibration isolation as an approach to improving the M-3 image resolution and measurement speed. This article presents the full dynamic model of the AVI system with the Mallock suspension used for the M-3 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. (C) 2004 American Institute of Physics.