engleski

Nano-positioning using an adaptive pulse width approach

Macro- and micro-dynamic mechanical non-linearities limiting the precision of conventional DC motor-driven positioning systems based on sliding and rolling elements have been characterized experimentally via a laser interferometric system. The obtained results confirm recent tribological models. In particular, the parameters describing the non-linear elastic and plastic phenomena related to pre-sliding displacement have been identified and used to develop an integrated system model. It was therefore possible to prove that, in the range of displacements corresponding to the pre-sliding phase, there is a quadratic dependence between the duration of an actuating impulsive force and the resulting displacement. According to a pulse width scheme, a control law has been implemented whose adaptive structure compensates for the position and time variability of the observed non-linear effects. The application of the proposed approach to both short and long travel ranges and the reached nanometric accuracies confirm the applicability of the proposed control scheme to compensate concurrently the macro- and the micro-dynamic effects.

nano-positioning; mechanical non-linearities; pre-sliding displacement; pulse width actuation

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