Embedded Grating Sensing and Compensation Enabling Cross-Scale Nanopositioning

Grating displacement sensing is regarded as one of the key technologies for achieving cross-scale nanopositioning. This paper proposes a real-time grating sensing correction and compensation technology to enhance the performance of the embedded grating displacement sensor in Cross-scale piezoelectric actuators (CSPAs), thereby enabling nano-scale motion positioning of CSPAs. Firstly, based on the principle of diffracted image reflection, a miniaturized grating sensing unit that can be monolithically integrated with the CSPA structure is designed. Secondly, an online self-correction algorithm based on amplitude iteration is proposed to dynamically eliminate DC offset and amplitude imbalance errors in the signals. Furthermore, a real-time error compensation strategy is constructed to compensate for inherent periodic errors and measurement lag errors of the system induced by stick-slip effects. Experimental results demonstrate that, with the proposed technology, the embedded grating displacement sensor can achieve a detection resolution of 0.9 nm within the full stroke. The CSPA integrated with this sensor achieved a positioning accuracy within ±1.3 nm over its scanning range, and a full-stroke bidirectional positioning consistency of 3.093 ± 1.358 nm.