A novel digital charge-based displacement estimator for sensorless control of a grounded-load piezoelectric tube actuator

Mohsen Bazghaleh*, Steven Grainger, Morteza Mohammadzaheri, Ben Cazzolato, Tien-Fu Lu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


Piezoelectric tube actuators are widely used in nanopositioning applications, especially in scanning probe microscopes to manipulate matter at nanometer scale. Accurate displacement control of these actuators is critical, and in order to avoid the expense and practical limits of highly accurate displacement sensors, sensorless control has recently attracted much attention. As the electrical charge on these actuators is an accurate indicator of their displacement exhibiting almost no hysteresis over a wide range of frequencies, it suggests that charge measurement can replace displacement sensors. However, charge-based methods suffer from poor low frequency response and voltage drop across the sensing capacitor. In this paper, a displacement estimator is presented that complements a digitally implemented charge amplifier with an artificial neural network (ANN) designed and trained to estimate the piezoelectric tube's displacement using the piezoelectric voltage at low frequencies of excitation where the charge methods fail. A complementary filter combines the grounded-load digital charge amplifier (GDCDE) and the ANN to estimate displacement over a wide bandwidth and to overcome drift. The discrepancy between the desired and estimated displacement is fed back to the piezoelectric actuator using proportional control. Experimental results highlight the effectiveness of the proposed design.

Original languageEnglish
Pages (from-to)91-98
Number of pages8
JournalSensors and Actuators A: Physical
Publication statusPublished - 15 Aug 2013


  • Artificial neural network
  • Complementary filter
  • Displacement estimation
  • Piezoelectric tube actuators
  • Sensorless control

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering


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